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Sample records for composite hollow spheres

  1. A novel approach to fabrication of superparamagnetite hollow silica/magnetic composite spheres

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Junjie, E-mail: yuanjunjie@tongji.edu.c [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China); Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433 (China); Zhang Xiong; Qian He [School of Materials Science and Engineering, Tongji University, Shanghai 200092 (China)

    2010-08-15

    We described a method for synthesizing hollow silica/magnetic composite spheres using sulfonic acid functionalized hollow silica spheres (SAFHSS) as templates. The Fe{sub 3}O{sub 4} nanoparticles were deposited on or imbedded in the hollow silica shell by a precipitation reaction. The morphologies, composition and properties of the hollow composite spheres were characterized by transmission electron microscopy, Fourier transform infrared analysis, X-ray diffraction measurement and vibrating-sample magnetometry measurement. The results indicated crystal sizes and amount of the Fe{sub 3}O{sub 4} nanoparticles on the SAFHSS. The magnetic properties of the hollow composite spheres were controlled by adjusting the proportion between Fe{sup 2+} and Fe{sup 3+} and iron ion total concentration. When appropriate loading species were added into the system, superparamagnetite hollow composite spheres were obtained. The method also could be applicable to prepare other superparamagnetite hollow silica/ferrite composite spheres.

  2. Preparation of SnO 2 /Carbon Composite Hollow Spheres and Their Lithium Storage Properties

    KAUST Repository

    Lou, Xiong Wen; Deng, Da; Lee, Jim Yang; Archer, Lynden A.

    2008-01-01

    In this work, we present a novel concept of structural design for preparing functional composite hollow spheres and derived double-shelled hollow spheres. The approach involves two main steps: preparation of porous hollow spheres of one component and deposition of the other component onto both the interior and exterior surfaces of the shell as well as in the pores. We demonstrate the concept by preparing SnO2/carbon composite hollow spheres and evaluate them as potential anode materials for lithium-ion batteries. These SnO2/carbon hollow spheres are able to deliver a reversible Li storage capacity of 473 mA h g-1 after 50 cycles. Unusual double-shelled carbon hollow spheres are obtained by selective removal of the sandwiched porous SnO2 shells. © 2008 American Chemical Society.

  3. Preparation of SnO 2 /Carbon Composite Hollow Spheres and Their Lithium Storage Properties

    KAUST Repository

    Lou, Xiong Wen

    2008-10-28

    In this work, we present a novel concept of structural design for preparing functional composite hollow spheres and derived double-shelled hollow spheres. The approach involves two main steps: preparation of porous hollow spheres of one component and deposition of the other component onto both the interior and exterior surfaces of the shell as well as in the pores. We demonstrate the concept by preparing SnO2/carbon composite hollow spheres and evaluate them as potential anode materials for lithium-ion batteries. These SnO2/carbon hollow spheres are able to deliver a reversible Li storage capacity of 473 mA h g-1 after 50 cycles. Unusual double-shelled carbon hollow spheres are obtained by selective removal of the sandwiched porous SnO2 shells. © 2008 American Chemical Society.

  4. Fabrication of porous silver/titania composite hollow spheres with enhanced photocatalytic performance

    International Nuclear Information System (INIS)

    Li, Sa; Halperin, Shakked O.; Wang, Chang-An

    2015-01-01

    Silver/titania composite hollow spheres were first synthesized through an in-situ chemical reaction using functional-grouped carbon spheres as the template in this study. The prepared samples were characterized through an X-ray diffraction, N 2 adsorption–desorption, scanning electron microscopy, transmission electron microscopy and UV–Vis spectrophotometer. The photocatalytic activity of as-prepared samples was evaluated by photocatalytic decolorization of Methyl orange (MO) aqueous solution at ambient temperature under UV light. We found a structure with an optimal Ag:TiO 2 composition that exhibited a photodecomposition rate constant more than twice as high as titania hollow spheres lacking silver, and over three times higher than a commercial photocatalyst. - Highlights: • Ag/silver composites. • Hollow spheres. • Photocatalysis enhancement

  5. Experimental Investigation and Discrete Element Modelling of Composite Hollow Spheres Subjected to Dynamic Fracture

    Directory of Open Access Journals (Sweden)

    Arthur Coré

    2017-01-01

    Full Text Available This paper deals with the characterization and the numerical modelling of the collapse of composite hollow spherical structures developed to absorb energy during high velocity impacts. The structure is composed of hollow spheres (ϕ=2–30 mm made of epoxy resin and mineral powder. First of all, quasi-static and dynamic (v=5 mm·min−1 to v=2 m·s−1 compression tests are conducted at room temperature on a single sphere to study energy dissipation mechanisms. Fracture of the material appears to be predominant. A numerical model based on the discrete element method is investigated to simulate the single sphere crushing. The stress-strain-time relationship of the material based on the Ree-Eyring law is numerically implemented. The DEM modelling takes naturally into account the dynamic fracture and the crack path computed is close to the one observed experimentally in uniaxial compression. Eventually, high velocity impacts (v>100 m·s−1 of a hollow sphere on a rigid surface are conducted with an air cannon. The numerical results are in good agreement with the experimental data and demonstrate the ability of the present model to correctly describe the mechanical behavior of brittle materials at high strain rate.

  6. Fabrication of hollow silica–zirconia composite spheres and their activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Hosoya, Tatsuya; Toyama, Naoki [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-09-01

    Highlights: • Hollow silica–zirconia composite spheres were fabricated on polystyrene templates by the sol–gel method. • We study the effect of preparation conditions on the activity for hydrolytic dehydrogenation of ammonia borane. • The activity of hollow silica–zirconia composite spheres depends on wall thickness. - Abstract: In this paper, we report fabrication of hollow silica–zirconia composite spheres by polystyrene (PS) template method and control of wall thickness of the hollow spheres in nanoscale. Both the hollow spheres before and after calcination were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), elemental analysis, and powder X-ray diffraction analysis (XRD). Morphology of the hollow spheres does not significantly change after calcination from the results of SEM and TEM images, while the amount of residual PS templates drastically decreases via the calcination procedure from the results of FTIR and elemental analysis. The sample after calcination mainly includes amorphous silica from the results of XRD, indicating that the hollow silica–zirconia composite spheres consist of amorphous phases and/or fine particles. Wall thicknesses of the samples after calcination are controlled by adjusting the amount of PS template suspension, and hollow silica–zirconia composite spheres with the wall thicknesses of 17.5, 15.0, 10.0, and 2.0 nm are obtained using the PS template suspension of 25.0, 33.5, 100.0, and 400.0 g, respectively. The activities of the hollow spheres for hydrolytic dehydrogenation of ammonia borane (NH{sub 3}BH{sub 3}) were compared. The evolutions of 2.0, 3.1, 5.0, and 8.0 mL hydrogen from aqueous NH{sub 3}BH{sub 3} solution were finished in about 4, 5, 3, and 7 min in the presence of the hollow spheres with wall thicknesses of 17.5, 15.0, 10.0, and 2.0 nm, respectively. The molar ratios of the hydrolytically generated hydrogen to

  7. Method for producing small hollow spheres

    International Nuclear Information System (INIS)

    Hendricks, C.D.

    1979-01-01

    A method is described 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. 600 0 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 3 μm) 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

  8. Influence of preparation conditions of hollow silica–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Seki, Ayano [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Engineering, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-03-05

    Highlights: • We study influence of preparation conditions on activity of hollow silica–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Si+Ni content. • The particle size distribution affects the activity and reducibility of active nickel species. • The amount of PS residue in the hollow spheres decreases by treatment of as-prepared sample in toluene. -- Abstract: In this paper, we investigated influence of preparation conditions of hollow silica–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane. In the preparation method of this study, when silica–nickel composite shells were coated on polystyrene templates by the sol–gel method using L(+)-arginine as the promoter for the reaction to form silica–nickel composite shell, the polystyrene templates were dissolved subsequently, even synchronously, in the same medium to form hollow spheres. The as-prepared silica–nickel composite spheres were characterized by transmission electron microscopy and scanning electron microscopy. The effects of Si+Ni content on the morphology were systematically evaluated. All the as-prepared hollow silica–nickel composite spheres have the similar morphology as identified by SEM and TEM measurement. Homogeneity of the hollow silica–nickel composite spheres increases with the increase in the Si+Ni content as shown by the laser diffraction particle size analysis. The catalytic activities of the hollow silica–nickel composite spheres for hydrolytic dehydrogenation of ammonia borane prepared with different Si+Ni contents were compared. The catalytic activity for the hydrogen evolution in the presence of the hollow spheres increases with the increase of Si+Ni content. The results of FTIR spectra of the hollow silica–nickel composite spheres indicate that a certain amount of residual PS templates exists in hollow silica

  9. Influence of preparation conditions of hollow titania–nickel composite spheres on their catalytic activity for hydrolytic dehydrogenation of ammonia borane

    Energy Technology Data Exchange (ETDEWEB)

    Umegaki, Tetsuo, E-mail: umegaki.tetsuo@nihon-u.ac.jp [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Ohashi, Takato [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan); Xu, Qiang [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Kojima, Yoshiyuki [Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, 1-8-14, Kanda-Surugadai, Chiyoda-Ku, Tokyo 101-8308 (Japan)

    2014-04-01

    Highlights: • We study influence of preparation conditions on activity of hollow titania–nickel composite spheres. • The activity for hydrolytic dehydrogenation of NH{sub 3}BH{sub 3} increases with increase of Ti + Ni content. • The activity depends on the amount of PS residue in the hollow spheres. - Abstract: The present work reports influence of preparation conditions of hollow titania–nickel composite spheres on their morphology and catalytic activity for hydrolytic dehydrogenation of ammonia borane (NH{sub 3}BH{sub 3}). The as-prepared hollow titania–nickel composite spheres were characterized by transmission electron microscopy (TEM). Catalytic activities of the hollow spheres for hydrolytic dehydrogenation of aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution improve with the decrease of Ti + Ni content. From the results of FTIR spectra and elemental analysis, the amount of residual polystyrene (PS) templates is able to be reduced by increasing aging time for the preparation, and the catalytic activity of the hollow spheres increases when the amount of residual PS templates decreases. The carbon content in the hollow spheres prepared with aging time = 24 h is 17.3 wt.%, and the evolution of 62 mL hydrogen is finished in about 22 min in the presence of the hollow spheres from aqueous NaBH{sub 4}/NH{sub 3}BH{sub 3} solution. The molar ratio of the hydrolytically generated hydrogen to the initial NH{sub 3}BH{sub 3} in the presence of the hollow spheres is 2.7.

  10. Mesoporous hollow spheres from soap bubbling.

    Science.gov (United States)

    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. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

    Science.gov (United States)

    Liu, Yang; Zhang, Jieyu; Li, Ying; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Hu, Pengfei; Chou, Shulei; Wang, Guoxiu

    2017-01-01

    To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C), good high-rate discharge capacity (118 mAh g−1 at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure. PMID:29099814

  12. Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2017-11-01

    Full Text Available To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG as the solvent medium and cetyltrimethylammonium bromide (CTAB as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C, good high-rate discharge capacity (118 mAh g−1 at 10 C, and fine cycling stability (99.2% after 200 cycles at 0.1 C. The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure.

  13. Characterization of silane coated hollow sphere alumina-reinforced

    Indian Academy of Sciences (India)

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites ...

  14. Method and apparatus for producing small hollow spheres

    International Nuclear Information System (INIS)

    Hendricks, C.D.

    1979-01-01

    A method and apparatus are described 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 greater than or equal to 600 0 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 3 μm) 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

  15. TEACHING PHYSICS: Biking around a hollow sphere

    Science.gov (United States)

    Mak, Se-yuen; Yip, Din-yan

    1999-11-01

    The conditions required for a cyclist riding a motorbike in a horizontal circle on or above the equator of a hollow sphere are derived using concepts of equilibrium and the condition for uniform circular motion. The result is compared with an empirical analysis based on a video show. Some special cases of interest derived from the general solution are elaborated.

  16. Fe3O4/C composite with hollow spheres in porous 3D-nanostructure as anode material for the lithium-ion batteries

    Science.gov (United States)

    Yang, Zhao; Su, Danyang; Yang, Jinping; Wang, Jing

    2017-09-01

    3d transition-metal oxides, especially Fe3O4, as anode materials for the lithium-ion batteries have been attracting intensive attentions in recent years due to their high energy capacity and low toxicity. A new Fe3O4/C composite with hollow spheres in porous three-dimensional (3D) nanostructure, which was synthesized by a facile solvothermal method using FeCl3·6H2O and porous spongy carbon as raw materials. The specific surface area and microstructures of composite were characterized by nitrogen adsorption-desorption isotherm method, FE-SEM and HR-TEM. A homogeneous distribution of hollow Fe3O4 spheres (diameter ranges from 120 nm to 150 nm) in the spongy carbon (pore size > 200 nm) conductive 3D-network significantly reduced the lithium-ion diffusion length and increased the electrochemical reaction area, and further more enhanced the lithium ion battery performance, such as discharge capacity and cycle life. As an anode material for the lithium-ion battery, the title composite exhibit excellent electrochemical properties. The Fe3O4/C composite electrode achieved a relatively high reversible specific capacity of 1450.1 mA h g-1 in the first cycle at 100 mA g-1, and excellent rate capability (69% retention at 1000 mA g-1) with good cycle stability (only 10% loss after 100 cycles).

  17. Enhanced microwave absorption performance of lightweight absorber based on reduced graphene oxide and Ag-coated hollow glass spheres/epoxy composite

    International Nuclear Information System (INIS)

    Wang, Junpeng; Sun, Yu; Chen, Wei; Wang, Tao; Xu, Renxin; Wang, Jun

    2015-01-01

    Using a combination of Ag-coated hollow glass spheres (HGS@Ag) and a small quantity of graphene sheets within the epoxy matrix, we have prepared a novel lightweight high efficiency microwave absorption composite. Compared with pure HGS@Ag and graphene composite, the −10 dB absorption bandwidth and the minimum reflection loss of the novel composite are improved. Reflection loss exceeding −20 dB is obtained for composites in a wide frequency range and the minimum reflection loss reaches −46 dB while bandwidth less than −10 dB can reach up to 4.1 GHz when an appropriate absorber thickness between 2 and 3.5 mm is chosen. The enhanced microwave absorption performance of the novel composite is due to the enhanced dielectric response, enhanced conductivity, and the trap of electromagnetic radiation with increased propagation paths by multiple reflections

  18. Evolution of nickel sulfide hollow spheres through topotactic transformation

    Science.gov (United States)

    Wei, Chengzhen; Lu, Qingyi; Sun, Jing; Gao, Feng

    2013-11-01

    In this study, a topotactic transformation route was proposed to synthesize single-crystalline β-NiS hollow spheres with uniform phase and morphology evolving from polycrystalline α-NiS hollow spheres. Uniform polycrystalline α-NiS hollow spheres were firstly prepared with thiourea and glutathione as sulfur sources under hydrothermal conditions through the Kirkendall effect. By increasing the reaction temperature the polycrystalline α-NiS hollow spheres were transformed to uniform β-NiS hollow spheres. The β-NiS crystals obtained through the topotactic transformation route not only have unchanged morphology of hollow spheres but are also single-crystalline in nature. The as-prepared NiS hollow spheres display a good ability to remove the organic pollutant Congo red from water, which makes them have application potential in water treatment.In this study, a topotactic transformation route was proposed to synthesize single-crystalline β-NiS hollow spheres with uniform phase and morphology evolving from polycrystalline α-NiS hollow spheres. Uniform polycrystalline α-NiS hollow spheres were firstly prepared with thiourea and glutathione as sulfur sources under hydrothermal conditions through the Kirkendall effect. By increasing the reaction temperature the polycrystalline α-NiS hollow spheres were transformed to uniform β-NiS hollow spheres. The β-NiS crystals obtained through the topotactic transformation route not only have unchanged morphology of hollow spheres but are also single-crystalline in nature. The as-prepared NiS hollow spheres display a good ability to remove the organic pollutant Congo red from water, which makes them have application potential in water treatment. Electronic supplementary information (ESI) available: XRD patterns; SEM images and TEM images. See DOI: 10.1039/c3nr03371f

  19. Ni hollow spheres as catalysts for methanol and ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Changwei [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Hu, Yonghong; Rong, Jianhua; Liu, Yingliang [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2007-08-15

    In this paper, we successfully synthesized Ni hollow spheres consisting of needle-like nickel particles by using silica spheres as template with gold nanoparticles seeding method. The Ni hollow spheres are applied to methanol and ethanol electrooxidation in alkaline media. The results show that the Ni hollow spheres give a very high activity for alcohol electrooxidation at a very low nickel loading of 0.10 mg cm{sup -2}. The current on Ni hollow spheres is much higher than that on Ni particles. The onset potential and peak potential on Ni hollow spheres are more negative than that on Ni particles for methanol and ethanol electrooxidation. The Ni hollow spheres may be of great potential in alcohol sensor and direct alcohol fuel cells. (author)

  20. Determination of corrosion potential of coated hollow spheres

    International Nuclear Information System (INIS)

    Fedorkova, Andrea; Orinakova, Renata; Orinak, Andrej; Dudrova, Eva; Kupkova, Miriam; Kalavsky, Frantisek

    2008-01-01

    Copper hollow spheres were created on porous iron particles by electro-less deposition. The consequent Ni plating was applied to improve the mechanical properties of copper hollow micro-particles. Corrosion properties of coated hollow spheres were investigated using potentiodynamic polarisation method in 1 mol dm -3 NaCl solution. Surface morphology and composition were studied by scanning electron microscopy (SEM), light microscopy (LM) and energy-dispersive X-ray spectroscopy (EDX). Original iron particles, uncoated copper spheres and iron particles coated with nickel were studied as the reference materials. The effect of particle composition, particularly Ni content on the corrosion potential value was investigated. The results indicated that an increase in the amount of Ni coating layer deteriorated corrosion resistivity of coated copper spheres. Amount of Ni coating layer depended on conditions of Ni electrolysis, mainly on electrolysis time and current intensity. Corrosion behaviour of sintered particles was also explored by potentiodynamic polarisation experiments for the sake of comparison. Formation of iron rich micro-volumes on the particle surface during sintering caused the corrosion potential shift towards more negative values. A detailed study of the morphological changes between non-sintered and sintered micro-particles provided explanation of differences in corrosion potential (E corr )

  1. A novel synthesis of micrometer silica hollow sphere

    International Nuclear Information System (INIS)

    Pan Wen; Ye Junwei; Ning Guiling; Lin Yuan; Wang Jing

    2009-01-01

    Silica microcapsules (hollow spheres) were synthesized successfully by a novel CTAB-stabilized water/oil emulsion system mediated hydrothermal method. The addition of urea to a solution of aqueous phase was an essential step of the simple synthetic procedure of silica hollow spheres, which leads to the formation of silica hollow spheres with smooth shell during hydrothermal process. The intact hollow spheres were obtained by washing the as-synthesized solid products with distilled water to remove the organic components. A large amount of silanol groups were retained in the hollow spheres by this facile route without calcination. The morphologies and optical properties of the product were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the silica hollow spheres has been presented

  2. Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

    Directory of Open Access Journals (Sweden)

    Zhong Kuo

    2018-03-01

    Full Text Available In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

  3. Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

    Science.gov (United States)

    Zhong, Kuo; Song, Kai; Clays, Koen

    2018-03-01

    In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal) lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs) of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM) inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

  4. Fe2O3 hollow sphere nanocomposites for supercapacitor applications

    Science.gov (United States)

    Zhao, Yu; Wen, Yang; Xu, Bing; Lu, Lu; Ren, Reiming

    2018-02-01

    Nanomaterials have attracted increasing interest in electrochemical energy storage and conversion. Hollow sphere Fe2O3 nanocomposites were successfully prepared through facile low temperature water-bath method with carbon sphere as hard template. The morphology and microstructure of samples were characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM), respectively. Through hydrolysis mechanism, using ferric chloride direct hydrolysis, iron hydroxide coated on the surface of carbon sphere, after high temperature calcination can form the hollow spherical iron oxide materials. Electrochemical performances of the hollow sphere Fe2O3 nanocomposites electrodes were investigated by cyclic voltammery (CV) and galvanostatic charge/discharge. The Pure hollow sphere Fe2O3 nanocomposites achieves a specific capacitance of 125 F g-1 at the current density of 85 mA g-1. The results indicate that the uniform dispersion of hollow ball structure can effectively reduce the particle reunion in the process of charging and discharging.

  5. One step process of decomposition and polymerization to fabricate SiO{sub 2} hollow spheres/polyimide composite for foldable OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Kyu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Dong Won; Moon, Soo Hyun [School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Shin, Dong-Wook [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); College of Engineering, Mathematics and Physical Sciences, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom); Oh, Tae Sik [School of Mechanical and ICT Convergence Engineering, Sunmoon University, Asan 336-708 (Korea, Republic of); Yoo, Ji Beom, E-mail: jbyoo@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2017-03-15

    Graphical abstract: The SiO{sub 2} hollow spheres and polyimide hybrid synthesized using one step process, simultaneous occurrence of decomposition and polymerization (SODP) is useful with a ultra-low dielectric constant and high thermal stability for flexible OLED. - Highlights: • We fabricated hybrid films of SHS/PI by using a one step process with SODP. • The film has ultralow dielectric constant (50 vol% at k = 1.67). • There is no collapse of SiO{sub 2} hollow spheres in the PI matrix after bending test for 50,000 cycles. - Abstract: The fabrication of interlayer dielectrics (ILDs) in flexible organic light-emitting diodes (OLEDs) requires flexible materials with a low dielectric constant as well as materials with excellent electrical, thermal, and mechanical properties for optimal device performance. Hybrid films of SiO{sub 2} hollow spheres (SHS)/polyimide (PI) were prepared using a one-step process, with simultaneous occurrence of decomposition (polystyrene, PS) and polymerization (PI) (SODP). No collapse of SiO{sub 2} hollow spheres in PI was observed from 10 vol% to 60 vol% SHS in hybrid films. The dielectric constant of hybrid films was reduced from 3.45 to 1.67 and was saturated at above 50 vol% of SHS due to the maximum fill factor of SHS in the PI matrix. The thermal stability was excellent up to 500 °C due to the inherent thermal property of PI. After a bending test for 50,000 cycles at a bending radius of 1 mm, the SHS/PI hybrid films retained their dielectric constant and current density. These results indicate the hybrid film to be the most promising candidate for flexible ILDs with a low dielectric constant and high thermal stability for foldable OLEDs.

  6. One step process of decomposition and polymerization to fabricate SiO_2 hollow spheres/polyimide composite for foldable OLEDs

    International Nuclear Information System (INIS)

    Kim, Min Kyu; Kim, Dong Won; Moon, Soo Hyun; Shin, Dong-Wook; Oh, Tae Sik; Yoo, Ji Beom

    2017-01-01

    Graphical abstract: The SiO_2 hollow spheres and polyimide hybrid synthesized using one step process, simultaneous occurrence of decomposition and polymerization (SODP) is useful with a ultra-low dielectric constant and high thermal stability for flexible OLED. - Highlights: • We fabricated hybrid films of SHS/PI by using a one step process with SODP. • The film has ultralow dielectric constant (50 vol% at k = 1.67). • There is no collapse of SiO_2 hollow spheres in the PI matrix after bending test for 50,000 cycles. - Abstract: The fabrication of interlayer dielectrics (ILDs) in flexible organic light-emitting diodes (OLEDs) requires flexible materials with a low dielectric constant as well as materials with excellent electrical, thermal, and mechanical properties for optimal device performance. Hybrid films of SiO_2 hollow spheres (SHS)/polyimide (PI) were prepared using a one-step process, with simultaneous occurrence of decomposition (polystyrene, PS) and polymerization (PI) (SODP). No collapse of SiO_2 hollow spheres in PI was observed from 10 vol% to 60 vol% SHS in hybrid films. The dielectric constant of hybrid films was reduced from 3.45 to 1.67 and was saturated at above 50 vol% of SHS due to the maximum fill factor of SHS in the PI matrix. The thermal stability was excellent up to 500 °C due to the inherent thermal property of PI. After a bending test for 50,000 cycles at a bending radius of 1 mm, the SHS/PI hybrid films retained their dielectric constant and current density. These results indicate the hybrid film to be the most promising candidate for flexible ILDs with a low dielectric constant and high thermal stability for foldable OLEDs.

  7. A Convenient and Templated Method for the Fabrication of Monodisperse Micrometer Hollow Titania Spheres

    Directory of Open Access Journals (Sweden)

    Haibo Yao

    2013-01-01

    Full Text Available A simple and widely applicable methodology was presented to synthesize monodisperse micrometer hollow titania spheres (HTS based on the templating method. It was performed by using the preformed poly(styrene-acrylic acid (PSA as template spheres which was mixed with tetrabutyltitanate (TBOT in an ethanol solvent under steam treatment. The HTS which were obtained by the calcination of PSA/TiO2 composite core-shell spheres had a narrow particle size distribution and commendable surface topography characterized by SEM. The calcined HTS at 500°C displayed crystalline reflection peaks that were characteristic to the anatase phase by XRD. Moreover, some key influencing factors including TBOT concentration and reaction time were analyzed. As expected, the diameter of HTS could be readily controlled by altering the size of PSA template spheres. In addition, the approach was also applied to fabricate hollow zirconia spheres and other inorganic spheres.

  8. Hierarchical Ag/AgCl-TiO{sub 2} hollow spheres with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu Long; Yin, Hao Yong [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Nie, Qiu Lin, E-mail: nieqiulin@hdu.edu.cn [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Wei Wei [College of Materials Environment Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhang, Yang; LiYuan, Qiu [College of Science, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2017-01-01

    The hierarchical Ag/AgCl-TiO{sub 2} hollow spheres were synthesized by depositing Ag/AgCl nanoparticles on TiO{sub 2} hollow spheres via a precipitation photoreduction method, and they were further characterized using TGA, SEM, TEM, XRD, XPS, UV–vis DRS and photoelectric chemical analysis. The analysis showed that the hierarchical Ag/AgCl-TiO{sub 2} hollow spheres exhibited the highest photocatalytic activity, which was approximately 13 times higher than that of TiO{sub 2} hollow spheres. The high photocatalytic activity of the composites is due to efficient electron-hole pairs separation at the photocatalyst interfaces, and localized surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction. - Highlights: • TiO{sub 2} hollow spheres were prepared by a sacrificial template method. • The hollow spheres were modified with Ag/AgCl to form the heterojunctions. • The modification may produce synergistic effect of LSPR and hollow structure. • Visible light photocatalytic activity was enhanced on this hollow catalyst. • The mechanism of the improved photocatalytic performance was discussed.

  9. Electrodepositing of Au on hollow PS micro-spheres

    International Nuclear Information System (INIS)

    Sun Jingyuan; Zhang Yunwang; Du Kai; Wan Xiaobo; Xiao Jiang; Zhang Wei; Zhang Lin; Chen Jing

    2010-01-01

    Using the self-regulating new micro-sphere electrodepositing device, the techniques of electrodepositing gold on hollow PS micro-spheres were established. The experiment was carried out under the following conditions: voltage was about 0.7 ∼ 0.8 V, current density was 2.0 mA · cm -2 , the temperature was 45 degree C, cathode rotating rate was 250 r · min -1 , flow rate of the solution was 7 mL · min -1 · cm -2 . Hollow gold-plated micro-spheres were prepared with well spherical symmetry, uniform thickness and surface smoothness under 500 nm. The speed of the gold depositing was 6 μm · h -1 . (authors)

  10. Synthesis of solid and hollow ATO spheres by carbothermal reduction of ATO nanoparticles

    International Nuclear Information System (INIS)

    Chai Chunfang; Huang Zaiyin; Liao Dankui; Tan Xuecai; Wu Jian; Yuan Aiqun

    2007-01-01

    Solid and hollow ATO spheres were fabricated by heating ATO nanoparticles and graphite mixture in a tube furnace. The as-synthesized samples were characterized by EDS, XRD, FE-SEM, TEM and HRTEM. The size of the solid spheres could be controlled by adjusting the rate of Ar flow and deposition positions. The hollow spheres were synthesized in an alumina tube system under conditions of a relatively high oxygen concentration. The growth mechanism of solid and hollow spheres was analysed

  11. Hierarchical VOOH hollow spheres for symmetrical and asymmetrical supercapacitor devices

    Science.gov (United States)

    Jing, Xuyang; Wang, Cong; Feng, Wenjing; Xing, Na; Jiang, Hanmei; Lu, Xiangyu; Zhang, Yifu; Meng, Changgong

    2018-01-01

    Hierarchical VOOH hollow spheres with low crystallinity composed of nanoparticles were prepared by a facile and template-free method, which involved a precipitation of precursor microspheres in aqueous solution at room temperature and subsequent hydrothermal reaction. Quasi-solid-state symmetric and asymmetric supercapacitor (SSC and ASC) devices were fabricated using hierarchical VOOH hollow spheres as the electrodes, and the electrochemical properties of the VOOH//VOOH SSC device and the VOOH//AC ASC device were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Results demonstrated that the electrochemical performance of the VOOH//AC ASC device was better than that of the VOOH//VOOH SSC device. After 3000 cycles, the specific capacitance of the VOOH//AC ASC device retains 83% of the initial capacitance, while the VOOH//VOOH SSC device retains only 7.7%. Findings in this work proved that hierarchical VOOH hollow spheres could be a promising candidate as an ideal electrode material for supercapacitor devices.

  12. Recent progress in hollow sphere-based electrodes for high-performance supercapacitors

    Science.gov (United States)

    Zhao, Yan; Chen, Min; Wu, Limin

    2016-08-01

    Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

  13. Recent progress in hollow sphere-based electrodes for high-performance supercapacitors.

    Science.gov (United States)

    Zhao, Yan; Chen, Min; Wu, Limin

    2016-08-26

    Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

  14. Stress in piezoelectric hollow sphere with thermal gradient

    International Nuclear Information System (INIS)

    Saadatfar, M.; Rastgoo, A.

    2008-01-01

    The piezoelectric phenomenon has been exploited in science and engineering for decades. Recent advances in smart structures technology have led to a resurgence of interest in piezoelectricity, and in particular, in the solution of fundamental boundary value problems. In this paper, we develop an analytic solution to the axisymmetric problem of a radially polarized, spherically isotropic piezoelectric hollow sphere. The sphere is subjected to uniform internal pressure, or uniform external pressure, or both and thermal gradient. There is a constant thermal difference between its inner and outer surfaces. An analytic solution to the governing equilibrium equations (a coupled system of second-order ordinary differential equations) is obtained. On application of the boundary conditions, the problem is reduced to solving a system of linear algebraic equations. Finally, the stress distributions in the sphere are obtained numerically for two piezoceramics

  15. Three-dimensional interconnected cobalt oxide-carbon hollow spheres arrays as cathode materials for hybrid batteries

    Directory of Open Access Journals (Sweden)

    Jiye Zhan

    2016-06-01

    Full Text Available Hierarchical porous metal oxides arrays is critical for development of advanced energy storage devices. Herein, we report a facile template-assisted electro-deposition plus glucose decomposition method for synthesis of multilayer CoO/C hollow spheres arrays. The CoO/C arrays consist of multilayer interconnected hollow composite spheres with diameters of ∼350 nm as well as thin walls of ∼20 nm. Hierarchical hollow spheres architecture with 3D porous networks are achieved. As cathode of high-rate hybrid batteries, the multilayer CoO/C hollow sphere arrays exhibit impressive enhanced performances with a high capacity (73.5 mAh g−1 at 2 A g−1, and stable high-rate cycling life (70 mAh g−1 after 12,500 cycles at 2 A g−1. The improved electrochemical performance is owing to the composite hollow-sphere architecture with high contact area between the active materials and electrolyte as well as fast ion/electron transportation path.

  16. Graphene-Wrapped Ni(OH)2 Hollow Spheres as Novel Electrode Material for Supercapacitors.

    Science.gov (United States)

    Sun, Jinfeng; Wang, Jinqing; Li, Zhangpeng; Ou, Junfei; Niu, Lengyuan; Wang, Honggang; Yang, Shengrong

    2015-09-01

    Graphene-wrapped Ni(OH)2 hollow spheres were prepared via electrostatic interaction between poly(diallyldimethylammonium chloride) (PDDA) modified Ni(OH)2 and graphene oxide (GO) in an aqueous dispersion, followed by the reduction of GO. Morphological and structural analysis by field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis confirmed the successful coating of graphene on Ni(OH)2 hollow spheres with a content of 3.8 wt%. And then its application as electrode material for supercapacitor has been investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. Results show that the sample displays a high capacitance of 1368 F g(-1) at a current density of 1 A g(-1), much better than that of pure Ni(OH)2, illustrating that such composite is a promising candidate as electrode material for supercapacitors.

  17. Gamma Radiation Induced Preparation of Functional Conducting Polymer Hollow Spheres

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K. -P.; Gopalan, A. I.; Philips, M. F.; Jeong, K.M., E-mail: kplee@knu.ac.kr [Department of Chemistry Education, Teacher' s College, Kyungpook National University 1370, Sankyuk-dong, Buk-gu, Daegu 702-701 (Korea, Republic of)

    2010-07-01

    New materials are sought for applications in many of the emerging fields that include catalysis, sensors, biomedical, optics and electronic application. With the advent of nanotechnology, innovative materials with novel properties are being synthesized towards target applications. Changing the sizes of particles, chemical, optical, and mechanical properties of the materials can often be tailored according to the specific needs of the application. Nanocrystalline, nanoparticles, nanocapsules, nanoporous materials, nanofibers, nanowires, fullerenes, nanotubes, nanosprings, nanobelts, dendrimers and nanospheres, ets, are few of the nanostructured materials. The examples of nanostructured materials include semiconducting nanowire quantum dots for gas sensing and self-assembled flower-like architectures. Self-assembly of nanoparticles can result in specific structures with unique and useful electronic, optical, and magnetic properties. Self or induced assemby of simple nanoparticles and rods could result into complex geometries, such as nanoflowers, binary superlattices, optical grating. Over the past decade, hollow spherical nanomaterials have received considerable attention due to their interesting properties such as low density, high surface area and good permeation. Various methods like solvothermal, self-assembly, sonochemical, solvent evaporation, chemical vapor deposition, microwave-assisted aqueous hydrothermal and electrochemical are being pursued for the production of hollow spherical materials. Polymer capsules and hollow spheres have increasingly received interest because of their large surface area and potential applications in catalysis, controlled delivery, artificial cells, light fillers and photonics.

  18. Gamma Radiation Induced Preparation of Functional Conducting Polymer Hollow Spheres

    International Nuclear Information System (INIS)

    Lee, K.-P.; Gopalan, A.I.; Philips, M.F.; Jeong, K.M.

    2010-01-01

    New materials are sought for applications in many of the emerging fields that include catalysis, sensors, biomedical, optics and electronic application. With the advent of nanotechnology, innovative materials with novel properties are being synthesized towards target applications. Changing the sizes of particles, chemical, optical, and mechanical properties of the materials can often be tailored according to the specific needs of the application. Nanocrystalline, nanoparticles, nanocapsules, nanoporous materials, nanofibers, nanowires, fullerenes, nanotubes, nanosprings, nanobelts, dendrimers and nanospheres, ets, are few of the nanostructured materials. The examples of nanostructured materials include semiconducting nanowire quantum dots for gas sensing and self-assembled flower-like architectures. Self-assembly of nanoparticles can result in specific structures with unique and useful electronic, optical, and magnetic properties. Self or induced assemby of simple nanoparticles and rods could result into complex geometries, such as nanoflowers, binary superlattices, optical grating. Over the past decade, hollow spherical nanomaterials have received considerable attention due to their interesting properties such as low density, high surface area and good permeation. Various methods like solvothermal, self-assembly, sonochemical, solvent evaporation, chemical vapor deposition, microwave-assisted aqueous hydrothermal and electrochemical are being pursued for the production of hollow spherical materials. Polymer capsules and hollow spheres have increasingly received interest because of their large surface area and potential applications in catalysis, controlled delivery, artificial cells, light fillers and photonics

  19. Hollow-in-Hollow Carbon Spheres for Lithium-ion Batteries with Superior Capacity and Cyclic Performance

    International Nuclear Information System (INIS)

    Zang, Jun; Ye, Jianchuan; Fang, Xiaoliang; Zhang, Xiangwu; Zheng, Mingsen; Dong, Quanfeng

    2015-01-01

    Highlights: • Hollow-in-hollow structured HIHCS was synthesized via a facile templating strategy. • The HCS core and hollow carbon shell constitute the hollow-in-hollow structure. • The HIHCS exhibited superior rate capability and cycle stability as anode material. • The excellent performance is attributed to the unique hollow-in-hollow structure. - Abstract: Hollow spheres structured materials have been intensively pursued due to their unique properties for energy storage. In this paper, hollow-in-hollow carbon spheres (HIHCS) with a multi-shelled structure were successfully synthesized using a facile hard-templating procedure. When evaluated as anode material for lithium-ion batteries, the resultant HIHCS anode exhibited superior capacity and cycling stability than HCS. It could deliver reversible capacities of 937, 481, 401, 304 and 236 mAh g −1 at current densities of 0.1 A g −1 , 1 A g −1 , 2 A g −1 , 5 A g −1 and 10 A g −1 , respectively. And capacity fading is not apparent in 500 cycles at 5 A g −1 . The excellent performance of the HIHCS anode is ascribed to its unique hollow-in-hollow structure and high specific surface area.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

  1. A General Synthesis Strategy for Hierarchical Porous Metal Oxide Hollow Spheres

    Directory of Open Access Journals (Sweden)

    Huadong Fu

    2015-01-01

    Full Text Available The hierarchical porous TiO2 hollow spheres were successfully prepared by using the hydrothermally synthesized colloidal carbon spheres as templates and tetrabutyl titanate as inorganic precursors. The diameter and wall thickness of hollow TiO2 spheres were determined by the hard templates and concentration of tetrabutyl titanate. The particle size, dispersity, homogeneity, and surface state of the carbon spheres can be easily controlled by adjusting the hydrothermal conditions and adding certain amount of the surfactants. The prepared hollow spheres possessed the perfect spherical shape, monodispersity, and hierarchically pore structures, and the further experiment verified that the present approach can be used to prepare other metal oxide hollow spheres, which could be used as catalysis, fuel cells, lithium-air battery, gas sensor, and so on.

  2. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    International Nuclear Information System (INIS)

    Li Siheng; Wang Enbo; Tian Chungui; Mao Baodong; Kang Zhenhui; Li Qiuyu; Sun Guoying

    2008-01-01

    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 2 O 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 3+ and M 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 2 O 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

  3. Biomolecule-assisted construction of cadmium sulfide hollow spheres with structure-dependent photocatalytic activity.

    Science.gov (United States)

    Wei, Chengzhen; Zang, Wenzhe; Yin, Jingzhou; Lu, Qingyi; Chen, Qun; Liu, Rongmei; Gao, Feng

    2013-02-25

    In this study, we report the synthesis of monodispersive solid and hollow CdS spheres with structure-dependent photocatalytic abilities for dye photodegradation. The monodispersive CdS nanospheres were constructed with the assistance of the soulcarboxymthyi chitosan biopolymer under hydrothermal conditions. The solid CdS spheres were corroded by ammonia to form hollow CdS nanospheres through a dissolution-reprecipitation mechanism. Their visible-light photocatalytic activities were investigated, and the results show that both the solid and the hollow CdS spheres have visible-light photocatalytic abilities for the photodegradation of dyes. The photocatalytic properties of the CdS spheres were demonstrated to be structure dependent. Although the nanoparticles comprising the hollow spheres have larger sizes than those comprising the solid spheres, the hollow CdS spheres have better photocatalytic performances than the solid CdS spheres, which can be attributed to the special hollow structure. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Methodology for construction of hollow spheres for use in physical phantoms

    International Nuclear Information System (INIS)

    Oliveira, A.C.H.; Lima, F.R.A.; Oliveira, F.; Vieira, J.W.

    2015-01-01

    In positron emission tomography (PET), quantitative evaluation of spatial resolution/object size, attenuation and scatter effects is often performed using phantoms with hollow spheres. Fillable, plastic-walled spheres are commercially available in several sizes. Radioactive solutions in any concentration can be injected into the spheres. Hollow spheres have several desirable traits, including repeatable, consistent use, and standardization across measurements at different institutions, since identical items are distributed by a single manufacturer. The objective of this work is to describe a methodology for construction of hollow spheres using rapid prototyping. It was used the software SolidWork (2014) to create five 3D models of the hollow spheres with inner diameters of 10 mm, 13 mm, 17 mm, 22 mm, and 28 mm. These models were based on hollow spheres of NEMA/IEC PET body phantom. It was used a Cubex Duo 3D printer (3D Systems) to build the hollow spheres. The material used was the ABS (acrylonitrile butadiene styrene) resin. (authors)

  5. Synthesis of Hollow Silver Spheres using Spherical Vaterite-type Calcium Carbonate as Template

    Energy Technology Data Exchange (ETDEWEB)

    Park, Minyoung; Go, Hani; Kim, Jae-Hyun; Rhee, Seog Woo [Kongju National University, Kongju (Korea, Republic of)

    2016-03-15

    In this work, we describe the synthesis of hollow silver spheres using vaterite-type CaCO{sub 3} as template. The spherical vaterite-type CaCO{sub 3} was selectively precipitated d reaction of aqueous CaCl{sub 2} and Na{sub 2}CO{sub 3} in the presence of the polyelectrolyte poly(4-styrenesulfonate). Aqueous AgNO{sub 3} solution containing NH{sub 2}-functionalized CaCO{sub 3} particles was treated with reducing agents such as ascorbic acid, NaBH{sub 4}, and acetaldehyde, and the reduced silver particles were deposited on the surface of CaCO{sub 3}particles to form uniform silvershells. The CaCO{sub 3} used as template was removed from the CaCO{sub 3}/Ag composite by treatment with acid. Finally, the hollow silver sphere was obtained. The morphologies of product were investigated using electron microscopy, the chemical composition of the composite was analyzed using energy-dispersive X-ray spectroscopy, the vibration modes of the carbonate ion were investigated by Fourier transform infrared spectroscopy, the thermal mass change was measured using the thermogravimetric analysis, and the solid phases were confirmed by powder X-ray diffraction.

  6. Catalyst-Free Synthesis of Hollow-Sphere-Like ZnO and Its Photoluminescence Property

    Directory of Open Access Journals (Sweden)

    Junye Cheng

    2014-01-01

    Full Text Available Hollow-sphere-like ZnO was successfully prepared by a facile combustion route at 950°C, and no external catalysts or additives were introduced. The morphology and structure of the hollow-sphere-like ZnO were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, high-resolution transmission electron microscopy (HRTEM, and energy dispersive spectrometer (EDS. The possible growth mechanism was discussed in detail. In addition, the as-obtained hollow-sphere-like ZnO exhibited a strong green emission at 518 nm and a weak UV emission at 385 nm. We believe that the hollow-sphere-like ZnO material may be a good candidate for application in optical devices and catalyst systems.

  7. Self-assembly of calcium phosphate nanoparticles into hollow spheres induced by dissolved amino acids

    NARCIS (Netherlands)

    Hagmeyer, D.; Ganesan, K.; Ruesing, J.; Schunk, D.; Mayer, C.; Dey, A.; Sommerdijk, N.A.J.M.; Epple, M.

    2011-01-01

    Nanoparticles of calcium phosphate assemble spontaneously within a few seconds into hollow spheres with a diameter around 200–300 nm in the presence of dissolved amino acids and dipeptides. The process of formation was followed by cryo-transmission electron microscopy (cryoTEM), proving their hollow

  8. Hydrothermal synthesis of lindgrenite with a hollow and prickly sphere-like architecture

    International Nuclear Information System (INIS)

    Xu Jiasheng; Xue Dongfeng

    2007-01-01

    Lindgrenite [Cu 3 (OH) 2 (MoO 4 ) 2 ] with a hollow and prickly sphere-like architecture has been synthesized via a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates. The hierarchical lindgrenite particles are hollow and prickly spheres, which are comprised of numerous small crystal strips that are aligned perpendicularly to the spherical surface. Two factors are important for the formation of hollow and prickly architecture in the present process. One is the general phenomenon of Ostwald ripening in solution, which can be responsible for the hollow structure; the other is that lindgrenite crystals have a rhombic growth habit, which plays an important role in the formation of prickly surface. Furthermore, Cu 3 Mo 2 O 9 with the similar size and morphology can be easily obtained by a simple thermal treatment of the as-prepared lindgrenite in air atmosphere. - Graphical abstract: Lindgrenite [Cu 3 (OH) 2 (MoO 4 ) 2 ] with a hollow and prickly sphere-like architecture has been synthesized via a hydrothermal route. The hierarchical lindgrenite particles are hollow and prickly spheres, which are comprised of numerous crystal strips that are aligned perpendicularly to the spherical surface. Cu 3 Mo 2 O 9 with the similar size and morphology can be easily obtained by a thermal treatment of the as-prepared lindgrenite

  9. Novel one-step route for synthesizing CdS/polystyrene nanocomposite hollow spheres.

    Science.gov (United States)

    Wu, Dazhen; Ge, Xuewu; Zhang, Zhicheng; Wang, Mozhen; Zhang, Songlin

    2004-06-22

    CdS/polystyrene nanocomposite hollow spheres with diameters between 240 and 500 nm were synthesized under ambient conditions by a novel microemulsion method in which the polymerization of styrene and the formation of CdS nanoparticles were initiated by gamma-irradiation. The product was characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA), which show the walls of the hollow spheres are porous and composed of polystyrene containing homogeneously dispersed CdS nanoparticles. The quantum-confined effect of the CdS/polystyrene nanocomposite hollow spheres is confirmed by the ultraviolet-visible (UV-vis) and photoluminescent (PL) spectra. We propose that the walls of these nanocomposite hollow spheres originate from the simultaneous synthesis of polystyrene and CdS nanoparticles at the interface of microemulsion droplets. This novel method is expected to produce various inorganic/polymer nanocomposite hollow spheres with potential applications in the fields of materials science and biotechnology.

  10. Zinc oxide hollow micro spheres and nano rods: Synthesis and applications in gas sensor

    International Nuclear Information System (INIS)

    Jamil, Saba; Janjua, Muhammad Ramzan Saeed Ashraf; Ahmad, Tauqeer; Mehmood, Tahir; Li, Songnan; Jing, Xiaoyan

    2014-01-01

    Zinc oxide nano rods and micro hollow spheres are successfully fabricated by adopting a simple solvo-thermal approach without employing any surfactant/template by keeping heating time as variable. The prepared products are characterized by using different instruments such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). In order to investigate the morphological dependence on the reaction time, analogous experiments with various reaction times are carried out. Depending upon heating time, different morphological forms have been identified such as hollow microsphere (4 μm to 5 μm) and nano rods with an average diameter of approximately 100 nm. The fabricated materials are also tested for ethanol gas sensor applications and zinc oxide hollow microsphere proven to be an efficient gas sensing materials. Nitrogen adsorption–desorption measurement was performed to understand better performance of zinc oxide micro hollow spheres as effective ethanol gas sensing material. - Graphical abstract: Graphical abstract is represented by zinc oxide sphere (prepared by simple solvothermal approach), its XRD pattern(characterization) and finally its application in gas sensing. - Highlights: • Zinc oxide spheres were prepared by using solvothermal method. • Detailed description of the morphology of microspheres assembled by nano rods. • Formation mechanism of zinc oxide spheres assembled by nano rods. • Zinc oxide spheres and nano rods displayed very good gas sensing ability

  11. Synthesis of Hollow Sphere and 1D Structural Materials by Sol-Gel Process.

    Science.gov (United States)

    Li, Fa-Liang; Zhang, Hai-Jun

    2017-08-25

    The sol-gel method is a simple and facile wet chemical process for fabricating advanced materials with high homogeneity, high purity, and excellent chemical reactivity at a relatively low temperature. By adjusting the processing parameters, the sol-gel technique can be used to prepare hollow sphere and 1D structural materials that exhibit a wide application in the fields of catalyst, drug or gene carriers, photoactive, sensors and Li-ion batteries. This feature article reviewed the development of the preparation of hollow sphere and 1D structural materials using the sol-gel method. The effects of calcination temperature, soaking time, pH value, surfactant, etc., on the preparation of hollow sphere and 1D structural materials were summarized, and their formation mechanisms were generalized. Finally, possible future research directions of the sol-gel technique were outlined.

  12. Human serum albumin mediated self-assembly of gold nanoparticles into hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Nayak, Nimai C [Singapore-MIT Alliance, Manufacturing Systems and Technology Programme, Nanyang Technological University, 65 Nanyang Drive, 637460 (Singapore); Shin, Kwanwoo [Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsoo-dong, Mapo-gu, Seoul 121-742 (Korea, Republic of)], E-mail: ncnayak@gmail.com

    2008-07-02

    The assembly of nanoparticles in topologically predefined superstructures is an important area in nanoscale architecture. In this paper, we report an unusual aggregation phenomenon involving L-lysine capped gold nanoparticles and human serum albumin into hollow nanospheres. The electrostatic interaction between positively charged L-lysine capped gold nanoparticles and negatively charged human serum albumin at physiological pH led to the assembly of the gold nanoparticles into hollow spheres. The phenomenon can be explained by the dry hole opening mechanism.

  13. Human serum albumin mediated self-assembly of gold nanoparticles into hollow spheres

    International Nuclear Information System (INIS)

    Nayak, Nimai C; Shin, Kwanwoo

    2008-01-01

    The assembly of nanoparticles in topologically predefined superstructures is an important area in nanoscale architecture. In this paper, we report an unusual aggregation phenomenon involving L-lysine capped gold nanoparticles and human serum albumin into hollow nanospheres. The electrostatic interaction between positively charged L-lysine capped gold nanoparticles and negatively charged human serum albumin at physiological pH led to the assembly of the gold nanoparticles into hollow spheres. The phenomenon can be explained by the dry hole opening mechanism

  14. Designed fabrication of fluorine-doped carbon coated mesoporous TiO2 hollow spheres for improved lithium storage

    International Nuclear Information System (INIS)

    Geng, Hongbo; Ming, Hai; Ge, Danhua; Zheng, Junwei; Gu, Hongwei

    2015-01-01

    Graphical abstract: Hollow TiO 2 with mesoporous shell (MHTO) was successfully fabricated by a novel and controllable route, followed by fluorine-doped carbon coating the MHTO (MHTO-C/F), with the aim of enhancing the conductivity and stability of structures. - Highlights: • Anatase TiO 2 hollow spheres with mesoporous shells (MHTO) was fabricated via a facile and controllable route, to improve the lithium ion mobility as well as the stability of the architecture. • Fluorine-doped carbon derived from polyvinylidene difluoride was further encapsulated onto TiO 2 hollow spheres to improve the conductivity. • The composites could provide excellent electrochemical performance, which was desirable for the application of TiO 2 as an anode material in lithium ion batteries. - Abstract: In this manuscript, we demonstrated a facile route for the controllable design of “Fluorine (F)-doped carbon” (C/F)-treated TiO 2 hollow spheres with mesoporous shells (MHTO-C/F). The fabrication of this distinct mesoporous hollow structures and the C/F coating could effectively improve the electrolyte permeability and architectural stability, as well as electrical conductivity and lithium ion mobility. As anticipated, MHTO-C/F has several remarkable electrochemical properties, such as a high specific reversible capacity of 252 mA h g −1 , outstanding cycling stability of more than 210 mA h g −1 after 100 cycles at 0.5 C, and good rate performance of around 123 mA h g −1 at 5 C (1 C = 168 mA g −1 ). These properties are highly beneficial for lithium storage

  15. MoS2 coated hollow carbon spheres for anodes of lithium ion batteries

    International Nuclear Information System (INIS)

    Zhang, Yufei; Wang, Ye; Shi, Wenhui; Yang, Huiying; Yang, Jun; Huang, Wei; Dong, Xiaochen

    2016-01-01

    With the assistance of resorcinol–formaldehyde, MoS 2 coated hollow carbon spheres (C@MoS 2 ) were synthesized through a facile hydrothermal route followed by heat and alkali treatments. The measurements indicate that the hollow carbon spheres with an average diameter of 300 nm and shell thickness of 20 nm. And the hollow core are uniformly covered by ultrathin MoS 2 nanosheets with a length increased to 400 nm. The unique hollow structure and the synergistic effect between carbon layer and MoS 2 nanosheets significantly enhance the rate capability and electrochemical stability of C@MoS 2 spheres as anode material of lithium-ion battery. The synthesized C@MoS 2 delivered a capacity of 750 mAh g −1 at a current density of 100 mA g −1 . More importantly, the C@MoS 2 maintained a reversible capacity of 533 mAh g −1 even at a high current density of 1000 mA g −1 . The study indicated that MoS 2 coated hollow carbon spheres can be promising anode material for next generation high-performance lithium-ion batteries. (paper)

  16. Nanotubes within transition metal silicate hollow spheres: Facile preparation and superior lithium storage performances

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan; An, Yongling; Zhai, Wei; Gao, Xueping [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Feng, Jinkui, E-mail: jinkui@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Ci, Lijie [Key Laboratory for Liquid–Solid Structural Evolution & Processing of Materials (Ministry of Education), Jinan 250100 (China); Xiong, Shenglin [School of Materials Science and Engineering, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-10-15

    Highlights: • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} were successfully prepared by a facile hydrothermal method using SiO{sub 2} nanosphere. • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} were tested as anode materials for lithium batteries. • The hollow Co{sub 2}SiO{sub 4}, MnSiO{sub 3} and CuSiO{sub 3} delivered superior electrochemical performance. • The lithium storage mechanism is probe via cyclic voltammetry and XPS. - Abstract: A series of transition metal silicate hollow spheres, including cobalt silicate (Co{sub 2}SiO{sub 4}), manganese silicate (MnSiO{sub 3}) and copper silicate (CuSiO{sub 3}.2H{sub 2}O, CuSiO{sub 3} as abbreviation in the text) were prepared via a simple and economic hydrothermal method by using silica spheres as chemical template. Time-dependent experiments confirmed that the resultants formed a novel type of hierarchical structure, hollow spheres assembled by numerous one-dimensional (1D) nanotubes building blocks. For the first time, the transition metal silicate hollow spheres were characterized as novel anode materials of Li-ion battery, which presented superior lithium storage capacities, cycle performance and rate performance. The 1D nanotubes assembly and hollow interior endow this kind of material facilitate fast lithium ion and electron transport and accommodate the big volume change during the conversion reactions. Our study shows that low-cost transition metal silicate with rationally designed nanostructures can be promising anode materials for high capacity lithium-ion battery.

  17. Influence of dielectric polarization upon PD transients: Use of hollow dielectric spheres

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1997-01-01

    Hollow glass spheres have recently been employed to provide a reproducible source of partial discharges. The influence of the shell permittivity upon the PD transients is examined. It is shown that, relative to the non-shell situation, the magnitude of such transients may be increased or decrease......, depending on the ratio of the shell-to-bulk dielectric permittivities....

  18. Synthesis of Br-doped TiO{sub 2} hollow spheres with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qianqian; Zhu, Shengli, E-mail: slzhu@tju.edu.cn; Liang, Yanqin; Cui, Zhenduo; Yang, Xianjin [Tianjin University, School of Materials Science and Engineering (China); Liang, Chunyong [Hebei University of Technology, Research Institute for Energy Equipment Materials (China); Inoue, Akihisa [Tianjin University, School of Materials Science and Engineering (China)

    2017-02-15

    The Br-doped hollow TiO{sub 2} photocatalysts were prepared by a simple hydrothermal process on the carbon sphere template following with calcination at 400 °C. The structure and properties of photocatalysts were characterized by X-ray diffraction, Raman spectrum, scanning electron microscope, transmission electron microscopy, N{sub 2} desorption–adsorption, UV–Vis spectroscopy, and X-ray photoelectron spectroscopy. The TiO{sub 2} hollow spheres are in diameter of 500 nm with shell thickness of 50 nm. The shell is composed of small anatase nanoparticles with size of about 10 nm. The TiO{sub 2} hollow spheres exhibit high crystalline and high surface area of 89.208 m{sup 2}/g. With increasing content of Br doping, the band gap of TiO{sub 2} hollow spheres decreased from 2.85 to 1.75 eV. The formation of impurity band in the band gap would narrow the band gap and result in the red shift of absorption edge from 395 to 517 nm, which further enhances the photocatalytic activity. The appropriate Br doping improves the photocatlytic activity significantly. The TiO{sub 2} hollow spheres with 1.55% Br doping (0.5Br-TiO{sub 2}) exhibit the highest photocatalytic activity under full light. More than 98% of RhB, MO, and MB can be photodegraded using 0.5Br-TiO{sub 2} with concentration of 10 mg/L in 40, 30, and 30 min, respectively. The degradation rate of Br-doped photocatalysts was 40% faster than undoped ones.

  19. Synthesis of carbon-coated Na2MnPO4F hollow spheres as a potential cathode material for Na-ion batteries

    Science.gov (United States)

    Wu, Ling; Hu, Yong; Zhang, Xiaoping; Liu, Jiequn; Zhu, Xing; Zhong, Shengkui

    2018-01-01

    Hollow sphere structure Na2MnPO4F/C composite is synthesized through spray drying, following in-situ pyrolytic carbon coating process. XRD results indicate that the well crystallized composite can be successfully synthesized, and no other impurity phases are detected. SEM and TEM results reveal that the Na2MnPO4F/C samples show intact hollow spherical architecture, and the hollow spherical shells with an average thickness of 150 nm-250 nm are composed of nanosized primary particles. Furthermore, the amorphous carbon layer is uniformly coated on the surface of the hollow sphere, and the nanosized Na2MnPO4F particles are well embedded in the carbon networks. Consequently, the hollow sphere structure Na2MnPO4F/C shows enhanced electrochemical performance. Especially, it is the first time that the obvious potential platforms (∼3.6 V) are observed during the charge and discharge process at room temperature.

  20. Facile synthesis and electrochemical performances of hollow graphene spheres as anode material for lithium-ion batteries

    Science.gov (United States)

    Yao, Ran-Ran; Zhao, Dong-Lin; Bai, Li-Zhong; Yao, Ning-Na; Xu, Li

    2014-07-01

    The hollow graphene oxide spheres have been successfully fabricated from graphene oxide nanosheets utilizing a water-in-oil emulsion technique, which were prepared from natural flake graphite by oxidation and ultrasonic treatment. The hollow graphene oxide spheres were reduced to hollow graphene spheres at 500°C for 3 h under an atmosphere of Ar(95%)/H2(5%). The first reversible specific capacity of the hollow graphene spheres was as high as 903 mAh g-1 at a current density of 50 mAh g-1. Even at a high current density of 500 mAh g-1, the reversible specific capacity remained at 502 mAh g-1. After 60 cycles, the reversible capacity was still kept at 652 mAh g-1 at the current density of 50 mAh g-1. These results indicate that the prepared hollow graphene spheres possess excellent electrochemical performances for lithium storage. The high rate performance of hollow graphene spheres thanks to the hollow structure, thin and porous shells consisting of graphene sheets.

  1. Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance

    Science.gov (United States)

    Wei, Xiaobing; Gong, Cairong; Chen, Xujuan; Fan, Guoliang; Xu, Xinhua

    2017-03-01

    Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene (PS) latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency (up to about 43 000 plates/m) and appropriate asymmetry factors.

  2. Hierarchical hollow spheres of Fe2O3 @polyaniline for lithium ion battery anodes.

    Science.gov (United States)

    Jeong, Jae-Min; Choi, Bong Gill; Lee, Soon Chang; Lee, Kyoung G; Chang, Sung-Jin; Han, Young-Kyu; Lee, Young Boo; Lee, Hyun Uk; Kwon, Soonjo; Lee, Gaehang; Lee, Chang-Soo; Huh, Yun Suk

    2013-11-20

    Hierarchical hollow spheres of Fe2 O3 @polyaniline are fabricated by template-free synthesis of iron oxides followed by a post in- and exterior construction. A combination of large surface area with porous structure, fast ion/electron transport, and mechanical integrity renders this material attractive as a lithium-ion anode, showing superior rate capability and cycling performance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Nanoporous CuS nano-hollow spheres as advanced material for high-performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, Hamid [Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of); Moosavifard, Seyyed Ebrahim, E-mail: info_seyyed@yahoo.com [Young Researchers and Elite Club, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Elyasi, Saeed [Department of Chemical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Shahraki, Mohammad [Department of Chemistry, University of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of)

    2017-02-01

    Highlights: • Nanoporous CuS nano-hollow spheres were synthesized by a facile method. • Nano-hollow spheres have a large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). • Such unique structures exhibit excellent electrochemical properties for high-performance SCs. - Abstract: Due to unique advantages, the development of high-performance supercapacitors has stimulated a great deal of scientific research over the past decade. The electrochemical performance of a supercapacitor is strongly affected by the surface and structural properties of its electrode materials. Herein, we report a facile synthesis of high-performance supercapacitor electrode material based on CuS nano-hollow spheres with nanoporous structures, large specific surface area (97 m{sup 2} g{sup −1}) and nanoscale shell thickness (<20 nm). This interesting electrode structure plays a key role in providing more active sites for electrochemical reactions, short ion and electron diffusion pathways and facilitated ion transport. The CuS nano-hollow spheres electrode exhibits excellent electrochemical performance including a maximum specific capacitance of 948 F g{sup −1} at 1 A g{sup −1}, significant rate capability of 46% capacitance retention at a high current density of 50 A g{sup −1}, and outstanding long-term cycling stability at various current densities. This work not only demonstrates the promising potential of the CuS-NHS electrodes for application in high-performance supercapacitors, but also sheds a new light on the metal sulfides design philosophy.

  4. Copper Silicate Hydrate Hollow Spheres Constructed by Nanotubes Encapsulated in Reduced Graphene Oxide as Long-Life Lithium-Ion Battery Anode.

    Science.gov (United States)

    Wei, Xiujuan; Tang, Chunjuan; Wang, Xuanpeng; Zhou, Liang; Wei, Qiulong; Yan, Mengyu; Sheng, Jinzhi; Hu, Ping; Wang, Bolun; Mai, Liqiang

    2015-12-09

    Hierarchical copper silicate hydrate hollow spheres-reduced graphene oxide (RGO) composite is successfully fabricated by a facile hydrothermal method using silica as in situ sacrificing template. The electrochemical performance of the composite as lithium-ion battery anode was studied for the first time. Benefiting from the synergistic effect of the hierarchical hollow structure and conductive RGO matrix, the composite exhibits excellent long-life performance and rate capability. A capacity of 890 mAh/g is achieved after 200 cycles at 200 mA/g and a capacity of 429 mAh/g is retained after 800 cycles at 1000 mA/g. The results indicate that the strategy of combining hierarchical hollow structures with conductive RGO holds the potential in addressing the volume expansion issue of high capacity anode materials.

  5. Silicon hollow sphere anode with enhanced cycling stability by a template-free method

    Science.gov (United States)

    Chen, Song; Chen, Zhuo; Luo, Yunjun; Xia, Min; Cao, Chuanbao

    2017-04-01

    Silicon is a promising alternative anode material since it has a ten times higher theoretical specific capacity than that of a traditional graphite anode. However, the poor cycling stability due to the huge volume change of Si during charge/discharge processes has seriously hampered its widespread application. To address this challenge, we design a silicon hollow sphere nanostructure by selective etching and a subsequent magnesiothermic reduction. The Si hollow spheres exhibit enhanced electrochemical properties compared to the commercial Si nanoparticles. The initial discharge and charge capacities of the Si hollow sphere anode are 2215.8 mAh g-1 and 1615.1 mAh g-1 with a high initial coulombic efficiency (72%) at a current density of 200 mA g-1, respectively. In particular, the reversible capacity is 1534.5 mAh g-1 with a remarkable 88% capacity retention against the second cycle after 100 cycles, over four times the theoretical capacity of the traditional graphite electrode. Therefore, our work demonstrates the considerable potential of silicon structures for displacing commercial graphite, and might open up new opportunities to rationally design various nanostructured materials for lithium ion batteries.

  6. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin; Khanh, Vu Bao

    2017-01-01

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  7. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  8. Template free fabrication of hollow hematite spheres via a one-pot polyoxometalate-assisted hydrolysis process

    International Nuclear Information System (INIS)

    Mao Baodong; Kang Zhenhui; Wang Enbo; Tian Chungui; Zhang Zhiming; Wang Chunlei; Song Yanli; Li Meiye

    2007-01-01

    Uniform hollow hematite (α-Fe 2 O 3 ) spheres with diameter of about 600-700 nm and shell thickness lower than 100 nm are obtained by direct hydrothermal treatment of dilute FeCl 3 and tungstophosphoric acid H 3 PW 12 O 40 solution at 180 deg. C. The hollow spheres are composed of robust shells with small nanoparticles standing out of the surface and present a high-surface area and a weak ferromagnetic behavior at room temperature. The effect of concentration of H 3 PW 12 O 40 , reaction time and temperature for the formation of the hollow spheres are investigated in series of experiments. The formation of the hollow spheres may be ascribed to a polyoxometalte-assisted forced hydrolysis and dissolution process. - Graphical abstract: Uniform hollow hematite (α-Fe 2 O 3 ) spheres with diameter of about 600-700 nm and shell thickness lower than 100 nm are obtained by direct hydrothermal treatment of dilute FeCl 3 and tungstophosphoric acid H 3 PW 12 O 40 solution at 180 deg. C. The hollow spheres present a high surface area and weak ferromagnetic behavior at room temperature

  9. Facile synthesis and enhanced visible-light photocatalytic activity of micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jin [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); The Key Laboratory of Rare Earth Functional Materials and Applications, Zhoukou Normal University, Zhoukou 466001 (China); Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

    2015-03-15

    Graphical abstract: - Highlights: • Micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres were synthesized by a facile method. • The formation mechanism for the Ag{sub 2}ZnGeO{sub 4} hollow spheres was investigated. • The catalyst exhibited an enhanced visible-light photocatalytic activity. • The reactive species in the photocatalytic process were studied. - Abstract: Micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres were successfully synthesized by a one-step and low-temperature route under ambient pressure. The micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres have a diameter of 1–2 μm and their shells are composed of numerous nanoparticles and nanorods. The growth process of the micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres was investigated in detail. The results indicated that the morphologies and composition of Ag{sub 2}ZnGeO{sub 4} samples were strongly dependent on the dose of the AgNO{sub 3} and reaction time. Excessive AgNO{sub 3} was favorable for the nucleation and growth rate of Ag{sub 2}ZnGeO{sub 4} crystals and the formation of pure Ag{sub 2}ZnGeO{sub 4}. Moreover, the formation mechanism of the micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres is related to the Ostwald ripening. Under the same conditions, the photocatalytic activity of micro/nanostructured Ag{sub 2}ZnGeO{sub 4} hollow spheres is about 1.7 times and 11 times higher than that of bulk Ag{sub 2}ZnGeO{sub 4} and Degussa P25, respectively. These interesting findings could provide new insight on the synthesis of micro/nanostructured ternary-metal oxides with enhanced photocatalytic activity.

  10. Synthesis and release of trace elements from hollow and porous hydroxyapatite spheres

    International Nuclear Information System (INIS)

    Xia Wei; Grandfield, Kathryn; Schwenke, Almut; Engqvist, Haakan

    2011-01-01

    It is known that organic species regulate fabrication of hierarchical biological forms via solution methods. However, in this study, we observed that the presence of inorganic ions plays an important role in the formation and regulation of biological spherical hydroxyapatite formation. We present a mineralization method to prepare ion-doped hydroxyapatite spheres with a hierarchical structure that is free of organic surfactants and biological additives. Porous and hollow strontium-doped hydroxyapatite spheres were synthesized via controlling the concentration of strontium ions in a calcium and phosphate buffer solution. Similarly, fluoride and silicon-doped hydroxyapatite spheres were synthesized. While spherical particle formation was attainable at low and high temperature for Sr-doped hydroxyapatite, it was only possible at high temperature in the F/Si-doped system. The presence of inorganic ions not only plays an important role in the formation and regulation of biological spherical hydroxyapatite, but also could introduce pharmaceutical effects as a result of trace element release. Such ion release results showed a sustained release with pH responsive behavior, and significantly influenced the hydroxyapatite re-precipitation. These ion-doped hydroxyapatite spheres with hollow and porous structure could have promising applications as bone/tooth materials, drug delivery systems, and chromatography supports.

  11. Electrochemical characteristics of discrete, uniform, and monodispersed hollow mesoporous carbon spheres in double-layered supercapacitors.

    Science.gov (United States)

    Chen, Xuecheng; Kierzek, Krzysztof; Wenelska, Karolina; Cendrowski, Krzystof; Gong, Jiang; Wen, Xin; Tang, Tao; Chu, Paul K; Mijowska, Ewa

    2013-11-01

    Core-shell-structured mesoporous silica spheres were prepared by using n-octadecyltrimethoxysilane (C18TMS) as the surfactant. Hollow mesoporous carbon spheres with controllable diameters were fabricated from core-shell-structured mesoporous silica sphere templates by chemical vapor deposition (CVD). By controlling the thickness of the silica shell, hollow carbon spheres (HCSs) with different diameters can be obtained. The use of ethylene as the carbon precursor in the CVD process produces the materials in a single step without the need to remove the surfactant. The mechanism of formation and the role played by the surfactant, C18TMS, are investigated. The materials have large potential in double-layer supercapacitors, and their electrochemical properties were determined. HCSs with thicker mesoporous shells possess a larger surface area, which in turn increases their electrochemical capacitance. The samples prepared at a lower temperature also exhibit increased capacitance as a result of the Brunauer-Emmett-Teller (BET) area and larger pore size. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Comparison of NiS2 and α-NiS hollow spheres for supercapacitors, non-enzymatic glucose sensors and water treatment.

    Science.gov (United States)

    Wei, Chengzhen; Cheng, Cheng; Cheng, Yanyan; Wang, Yan; Xu, Yazhou; Du, Weimin; Pang, Huan

    2015-10-21

    NiS2 hollow spheres are successfully prepared by a one-step template free method. Meanwhile, α-NiS hollow spheres can also be synthesized via the calcination of the pre-obtained NiS2 hollow spheres at 400 °C for 1 h in air. The electrochemical performances of the as-prepared NiS2 and α-NiS hollow sphere products are evaluated. When used for supercapacitors, compared with NiS2 hollow spheres, the α-NiS hollow sphere electrode shows a large specific capacitance of 717.3 F g(-1) at 0.6 A g(-1) and a good cycle life. Furthermore, NiS2 and α-NiS hollow spheres are successfully applied to fabricate non-enzymatic glucose sensors. In particular, the α-NiS hollow spheres exhibit good catalytic activity for the oxidation of glucose, a fast amperometric response time of less than 5 s, and the detection limit is estimated to be 0.08 μM. More importantly, compared with other normally co-existing interfering species, such as ascorbic acid, uric acid and dopamine, the electrode modified with α-NiS hollow spheres shows good selectivity. Moreover, the α-NiS hollow spheres also present good capacity to remove Congo red organic pollutants from wastewater by their surface adsorption ability.

  13. Jingle-bell-shaped ferrite hollow sphere with a noble metal core: Simple synthesis and their magnetic and antibacterial properties

    Science.gov (United States)

    Li, Siheng; Wang, Enbo; Tian, Chungui; Mao, Baodong; Kang, Zhenhui; Li, Qiuyu; Sun, Guoying

    2008-07-01

    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 2O 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 3+ and M 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.

  14. Facile synthesis and microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere and multi-shelled NiO hollow sphere

    International Nuclear Information System (INIS)

    Wu, Hongjing; Wu, Guanglei; Wu, Qiaofeng; Wang, Liuding

    2014-01-01

    We reported the preparation of C@Ni–NiO core–shell hybrid solid spheres or multi-shelled NiO hollow spheres by combining a facile hydrothermal route with a calcination process in H 2 or air atmosphere, respectively. The synthesized C@Ni–NiO core–shell solid spheres with diameters of approximately 2–6 μm were in fact built from dense NiO nanoparticles coated by random two-dimensional metal Ni nanosheets without any visible pores. The multi-shelled NiO hollow spheres were built from particle-like ligaments and there are a lot of pores with size of several nanometers on the surface. Combined Raman spectra with X-ray photoelectron spectra (XPS), it suggested that the defects in the samples play a limited role in the dielectric loss. Compared with the other samples, the permeability of the samples calcined in H 2 and air was increased slightly and the natural resonance frequency shifted to higher frequency (7, 11 and 14 GHz, respectively), leading to an enhancement of microwave absorption property. For the sample calcined in H 2 , an optimal reflection loss less than − 10 was obtained at 7 GHz with a matching thickness of 5.0 mm. Our study demonstrated the potential application of C@Ni–NiO core–shell hybrid solid sphere or multi-shelled NiO hollow sphere as a more efficient electromagnetic (EM) wave absorber. - Highlights: • C@Ni–NiO core–shell hybrid solid sphere was synthesized by a facile method. • Multi-shelled NiO hollow sphere was synthesized by a facile method. • It suggested that the defects in the samples play a limited role in dielectric loss. • The permeability of the samples calcined in H 2 and air was increased. • Microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere was investigated

  15. Synthesis and characterization of Mg-doped ZnO hollow spheres

    International Nuclear Information System (INIS)

    Hammad, Talaat M.; Salem, Jamil K.

    2011-01-01

    Mg-doped ZnO nanoparticles were synthesized by a simple chemical method at low temperature with Mg:Zn atomic ratio from 0 to 7%. The synthesis process is based on the hydrolysis of zinc acetate dihydrate and magnesium acetate tetrahydrate were heated under refluxing at 65 °C using methanol as a solvent. X-ray diffraction analysis reveals that the Mg-doped ZnO crystallizes in a wurtzite structure with crystal size of 5–12 nm. These nanocrystals self-aggregated themselves into hollow spheres of size of 800–1100 nm. High resolution transmission electron microscopy images show that each sphere is made up of numerous nanoparticles of average diameter 5–11 nm. The XRD patterns, SEM and TEM micrographs of doping of Mg in ZnO confirmed the formation of hollow spheres indicating that the Mg 2+ is successfully substituted into the ZnO host structure of the Zn 2+ site. Furthermore, the UV–Vis spectra and photoluminescence (PL) spectra of the ZnO nanoparticles were also investigated. The band gap of the nanoparticles can be tuned in the range of 3.36–3.55 eV by the use of the dopants.

  16. Ultrafine Sn nanoparticles embedded in shell of N-doped hollow carbon spheres as high rate anode for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Peng; Cao, Zhenzhen; Wang, Chao; Zheng, Jiao [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Xu, Xinhua, E-mail: xhxutju@gmail.com [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China)

    2017-05-15

    Highlights: • Dynamic covalent bond in polymeric nanoparticles is used to induce hollow Sn{sup 4+}-MOPs. • Ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn{sup 4+}-MOPs precursor. • The composite exhibits superior cycle stability and rate capacity. - Abstract: A novel reversible interaction in polymeric nanoparticles is used to induce hollow Sn{sup 4+}-MOPs. Then ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn{sup 4+}-MOPs precursor. In this architecture, the N-doped carbon shells can effectively avoid the direct exposure of embedded Sn nanoparticles to the electrolyte and efficiently accommodate the volume change of Sn nanoparticles. Furthermore, the hollow structure of carbon sphere can prevent Sn nanoparticles aggregation over repeated cycling and shorten the diffusion path of both electrons and ions. As a consequence, this N-doped hollow Sn/C anode delivers a reversible capacity of 606 mA h g{sup −1} at a current density of 0.2 A g{sup −1} after 250 cycles and a reversible capacity of 221 mA h g{sup −1} even at a much higher current density of 10 A g{sup −1}, which are much better than those of pure Sn nanoparticles. The desirable cyclic stability and rate capability were attributed to the unique architecture that provided fast pathway for electron transport and simultaneously solved the major issues of Sn-based anodes, such as pulverization, aggregation and loss of electrical contact.

  17. Self-Assembled Hollow Spheres of β-Ni(OH) 2 and Their Derived Nanomaterials

    KAUST Repository

    Zhang, Shengmao

    2009-03-10

    This paper describes a novel solution-based chemical process to architect hollow spheres of β-Ni(OH) 2 with controllable sizes in submicrometer and micrometer regimes. In the synthesis, starting nickel salt (nitrate) is first converted to 6-coordinated nickel ion complex [Ni(EDA) 3] 2+ (bidentate ligand EDA = C 2H 4(NH 2) 2) to avoid rapid solid formation. Hollow and core - shell β-Ni(OH) 2 spheres can be obtained with this template-free approach under one-pot conditions. The β-Ni(OH) 2 spheres are constructed from petal-like nanobuilding units which in turn are formed from even smaller nanocrystallites. The obtained porous β-Ni(OH) 2 spheres have a large specific surface area and show a unimodal pore-size distribution. Several preparative parameters have been examined and optimized. In particular, the concentration of divalent nickel in the starting solutions plays an important role in controlling thickness of the petal-like β-Ni(OH) 2 flakes and diameter of spheres. The β-Ni(OH) 2 flakes self-assemble into final spherical products through a donut-like structural intermediate. Furthermore, the β-Ni(OH) 2 hollow spheres can be used as solid precursors to synthesize other nanostructured derivatives. In this work, phase pure inorganic nanostructures, carbon nanotube (CNT) - inorganic nanocomposites, and inorganic - inorganic nanocom-posites (e.g., NiO, Ni, NiO/Ni, Ni/β-Ni(OH) 2, CNTs/NiO, CNTs/Ni, Ni@CNTs, Fe(OH) 3/β-Ni(OH) 2, Co(OH) 2/β-Ni(OH) 2, and Mg(OH) 2/β-Ni(OH) 2) have been prepared via solid-state thermal decomposition, gas-phase reduction, solution-based reduction, surface oxidation, chemical vapor deposition, and liquid-phase deposition. A greater picture for general synthesis of Ni-containing nanomaterials is thus obtained. © 2009 American Chemical Society.

  18. Self-template synthesis of double shelled ZnS-NiS1.97 hollow spheres for electrochemical energy storage

    Science.gov (United States)

    Wei, Chengzhen; Ru, Qinglong; Kang, Xiaoting; Hou, Haiyan; Cheng, Cheng; Zhang, Daojun

    2018-03-01

    In this work, double shelled ZnS-NiS1.97 hollow spheres have been achieved via a simple self-template route, which involves the synthesis of Zn-Ni solid spheres precursors as the self-template and then transformation into double shelled ZnS-NiS1.97 hollow spheres by sulfidation treatment. The as-prepared double shelled ZnS-NiS1.97 hollow spheres possess a high surface area (105.26 m2 g-1) and porous structures. Benefiting from the combined characteristics of novel structures, multi-component, high surface area and porous. When applied as electrode materials for supercapacitors, the double shelled ZnS-NiS1.97hollow spheres deliver a large specific capacitance of 696.8C g-1 at 5.0 A g-1 and a remarkable long lifespan cycling stability (less 5.5% loss after 6000 cycles). Moreover, an asymmetric supercapacitor (ASC) was assembled by utilizing ZnS-NiS1.97 (positive electrode) and activated carbon (negative electrode) as electrode materials. The as-assembled device possesses an energy density of 36 W h kg-1, which can be yet retained 25.6 W h kg-1 even at a power density of 2173.8 W Kg-1, indicating its promising applications in electrochemical energy storage. More importantly, the self-template route is a simple and versatile strategy for the preparation of metal sulfides electrode materials with desired structures, chemical compositions and electrochemical performances.

  19. Synthesis and characterization of ZnO and TiO2 hollow spheres with enhanced photoreactivity

    International Nuclear Information System (INIS)

    Li Xiaofang; Lv Kangle; Deng Kejian; Tang Junfeng; Su Rong; Sun Jie; Chen Lianqing

    2009-01-01

    To study the relationship between the morphology and the photoreactivity of the catalyst, hollow spheres of two semiconductors of ZnO and TiO 2 were synthesized by using sulfonated polystyrene (PS) as template. The catalyst samples were then characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), diffuse reflectance spectra (DRS), transmission electron microscopy (TEM) and N 2 sorption. Reactive brilliant red X3B, an anionic organic dye, was used in this study as a model chemical with the aim of organic pollutants control. The results show that, whatever the catalyst was, both the adsorptive ability and photoreactivity of the hollow spheres were much higher than that of nanoparticles. The adsorption and photoreactivity of ZnO hollow spheres increased by a factor of 7.36 and 4.66, respectively compared with ZnO nanoparticles, while 3.74 times increased in adsorption and 3.41 times increased in photoreactivity for TiO 2 hollow spheres compared with TiO 2 nanoparticles. Correlations between adsorption and photoreactivity reflected the importance of adsorption in the enhanced photoreactivity of ZnO and TiO 2 hollow spheres

  20. Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

    Science.gov (United States)

    Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

    2017-04-01

    Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

  1. JOINT-INDUSTRY PARTNERSHIP TO DEVELOP A HOLLOW SPHERE DUAL-GRADIENT DRILLING SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    William C. Maurer; Colin Ruan; Greg Deskins

    2003-05-01

    Maurer Technology Inc. (MTI) formed a joint-industry partnership to fund the development of a hollow sphere dual-gradient drilling (DGD) system. Phase I consisted of collecting, compiling, analyzing, and distributing information and data regarding a new DGD system for use by the oil and gas industry. Near the end of Phase I, DOE provided funding to the project that was used to conduct a series of critical follow-on tests investigating sphere separation in weighted waterbase and oilbase muds. Drilling costs in deep water are high because seawater pressure on the ocean floor creates a situation where many strings of casing are required due to the relatively close spacing between fracture and pore pressure curves. Approximately $100 million have been spent during the past five years on DGD systems that place pumps on the seafloor to reduce these drilling problems by reducing the annulus fluid pressure at the bottom of the riser. BP estimates that a DGD system can save $9 million per well in the Thunderhorse Field and Conoco estimates it can save $5 to $15 million per well in its deepwater operations. Unfortunately, previous DGD development projects have been unsuccessful due to the high costs ($20 to $50 million) and reliability problems with seafloor pump systems. MTI has been developing a simple DGD system concept that would pump hollow glass spheres into the bottom of the riser to reduce density of the mud in the riser. This eliminates the requirement for seafloor pumps and replaces them with low cost mud pumps, shale shakers, and other oilfield equipment that can be operated on the rig by conventional crews. A $1.8 million Phase I joint-industry project funded by five service companies and three operators showed that hollow spheres could be pumped well, but difficulties were encountered in separating the spheres from a polymer mud supplied by Halliburton due to the high viscosity of this mud at the low shear rates encountered on oilfield shale shaker screens. As a

  2. Double hollow MoS{sub 2} nano-spheres: Synthesis, tribological properties, and functional conversion from lubrication to photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yueru [Department of Chemical and Materials Engineering, Hefei University, Hefei 230601 (China); Hu, Kunhong, E-mail: hukunhong@163.com [Department of Chemical and Materials Engineering, Hefei University, Hefei 230601 (China); Hu, Enzhu; Guo, Jianhua; Han, Chengliang [Department of Chemical and Materials Engineering, Hefei University, Hefei 230601 (China); Hu, Xianguo [Institute of Tribology, Hefei University of Technology, Hefei 230009 (China)

    2017-01-15

    Highlights: • Novel double-hollow-sphere MoS{sub 2} nanoparticles were synthesized on sericite. • Friction and wear decreased by 22.4 and 63.5% by the novel MoS{sub 2}/sericite. • Friction induced conversion of MoS{sub 2}/sericite from lubricant to catalyst. • MoS{sub 2}/sericite can be used as a photocatalyst after lubricating service life. • A possible approach was proposed for designing a novel green lubricant. - Abstract: Molybdenum disulfide (MoS{sub 2}) has extensive applications in industries as solid lubricants and catalysts. To improve the lubricating performance of MoS{sub 2}, novel double-hollow-sphere MoS{sub 2} (DHSM) nanoparticles with an average diameter of approximately 90 nm were synthesized on sericite mica (SM). When the DHSM/SM composite was used as an additive in polyalphaolefin oil, friction and wear decreased by 22.4% and 63.5% respectively. The low friction and wear were attributed to the easy exfoliation of DHSM. The DHSM/SM composite was then rubbed under 40 MPa for 1 h to investigate the exfoliation and functional conversion behaviors of DHSM. Results showed that DHSM (lubricating structure) on SM could be completely exfoliated into nanosheets (catalytic structure) by rubbing. The nanosheets exfoliated from DHSM presented good photocatalytic activity for the removal of organic compounds from waste water. This work provided both a novel solid lubricant for industrial applications and a possible approach to designing a novel green lubricant for use as a photocatalyst in organic-waste treatment after lubricating service life.

  3. Novel syntactic foams made of ceramic hollow micro-spheres and starch: theory, structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.M.; Kim, H.S. [University of Newcastle, Callaghan, NSW (Australia). Faculty of Engineering & Built Environments

    2007-08-15

    Novel syntactic foams for potential building material applications were developed using starch as binder and ceramic hollow micro-spheres available as waste from coal-fired power stations. Foams of four different micro-sphere size groups were manufactured with either pre- or post-mould gelatinization process. They were of ternary system including voids with a foam density range of approximately 0.33-0.44 g/cc. Compressive failure behaviour and mechanical properties of the manufactured foams were evaluated. Not much difference in failure behaviour or in mechanical properties between the two different processes (pre- and post-mould gels) was found for a given binder content. Compressive failure of all syntactic foams was of shear on plane inclined 45 degrees to compressive loading direction. Failure surfaces of most syntactic foams were characterized by debonded micro-spheres. Compressive strength and modulus of syntactic foams were found to be dependant mainly on binder content but mostly independent of micro-sphere size. Some conditions of relativity arising from properties of constituents leading to the rule of mixtures relationships for compressive strength and to understanding of compressive/transitional failure behaviour were developed. The developed relationships based on the rule of mixtures were partially verified. Some formation of starch webs on failure surfaces was discussed.

  4. Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method

    Science.gov (United States)

    Gopi, D.; Indira, J.; Kavitha, L.; Sekar, M.; Mudali, U. Kamachi

    Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology.

  5. Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method.

    Science.gov (United States)

    Gopi, D; Indira, J; Kavitha, L; Sekar, M; Mudali, U Kamachi

    2012-07-01

    Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Hollow carbon sphere/metal oxide nanocomposites anodes for lithium-ion batteries

    International Nuclear Information System (INIS)

    Wenelska, K.; Ottmann, A.; Schneider, P.; Thauer, E.; Klingeler, R.; Mijowska, E.

    2016-01-01

    HCS (Hollow carbon spheres) covered with metal oxide nanoparticles (SnO_2 and MnO_2, respectively) were successfully synthesized and investigated regarding their potential as anode materials for lithium-ion batteries. Raman spectroscopy shows a high degree of graphitization for the HCS host structure. The mesoporous nature of the nanocomposites is confirmed by Brunauer–Emmett–Teller analysis. For both metal oxides under study, the metal oxide functionalization of HCS yields a significant increase of electrochemical performance. The charge capacity of HCS/SnO_2 is 370 mA hg"−"1 after 45 cycles (266 mA hg"−"1 in HCS/MnO_2) which clearly exceeds the value of 188 mA hg"−"1 in pristine HCS. Remarkably, the data imply excellent long term cycling stability after 100 cycles in both cases. The results hence show that mesoporous HCS/metal oxide nanocomposites enable exploiting the potential of metal oxide anode materials in Lithium-ion batteries by providing a HCS host structure which is both conductive and stable enough to accommodate big volume change effects. - Highlights: • Strategy to synthesize hollow carbon spheres decorated by metal oxides nanoparticles. • High-performance of HCS/MOx storage as mesoporous hybrid material. • The results hence demonstrate high electrochemical activity of the HCS/MOx.

  7. Electrochemical performance of Ni/TiO{sub 2} hollow sphere in proton exchange membrane water electrolyzers system

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Jayeeta; Srivastava, Rohit; Srivastava, Prem Kumar [Birla Institute of Technology, Jharkhand (India)

    2013-08-15

    This work presents the electrocatalytic evaluation of Ni/TiO{sub 2} hollow sphere materials in PEM water electrolysis cell. All the electrocatalysts have shown remarkably enhanced electrocatalytic properties in comparison with their performance in aqueous electrolysis cell. According to cyclic voltammetric results, 0.36 A cm{sup −2} peak current density has been exhibited in hydrogen evolution reaction (HER) from 30 wt% Ni/TiO{sub 2} electrocatalyst. 15 wt% Ni-doped titania sample has shown the best result in oxygen evolution reaction (OER) with the anodic peak current density of 0.3 A cm{sup −2}. In the anodic polarization curves, the performance of 15 wt% Ni/TiO{sub 2} hollow sphere electrocatalyst was evaluated up to 140 mA cm{sup −2} at comparatively lower over-potential value. 20 wt% Ni/TiO{sub 2} hollow sphere electrocatalyst has also shown electrochemical stability in PEM water electrolyzer for 48 h long analysis. The comparative electrocatalytic behavior of hollow spherical materials with non-sphericals is also presented, which clearly shows the influence of hollow spherical structure in greater electrocatalytic activity of the materials. The physical characterization of all the hollow spherical materials is presented in this work, which has confirmed their better electrochemical behavior in PEM water electrolyzer.

  8. Electrochemical performance of Ni/TiO_2 hollow sphere in proton exchange membrane water electrolyzers system

    International Nuclear Information System (INIS)

    Chattopadhyay, Jayeeta; Srivastava, Rohit; Srivastava, Prem Kumar

    2013-01-01

    This work presents the electrocatalytic evaluation of Ni/TiO_2 hollow sphere materials in PEM water electrolysis cell. All the electrocatalysts have shown remarkably enhanced electrocatalytic properties in comparison with their performance in aqueous electrolysis cell. According to cyclic voltammetric results, 0.36 A cm"−"2 peak current density has been exhibited in hydrogen evolution reaction (HER) from 30 wt% Ni/TiO_2 electrocatalyst. 15 wt% Ni-doped titania sample has shown the best result in oxygen evolution reaction (OER) with the anodic peak current density of 0.3 A cm"−"2. In the anodic polarization curves, the performance of 15 wt% Ni/TiO_2 hollow sphere electrocatalyst was evaluated up to 140 mA cm"−"2 at comparatively lower over-potential value. 20 wt% Ni/TiO_2 hollow sphere electrocatalyst has also shown electrochemical stability in PEM water electrolyzer for 48 h long analysis. The comparative electrocatalytic behavior of hollow spherical materials with non-sphericals is also presented, which clearly shows the influence of hollow spherical structure in greater electrocatalytic activity of the materials. The physical characterization of all the hollow spherical materials is presented in this work, which has confirmed their better electrochemical behavior in PEM water electrolyzer

  9. Hierarchical FeTiO3-TiO2 hollow spheres for efficient simulated sunlight-driven water oxidation.

    Science.gov (United States)

    Han, Taoran; Chen, Yajie; Tian, Guohui; Wang, Jian-Qiang; Ren, Zhiyu; Zhou, Wei; Fu, Honggang

    2015-10-14

    Oxygen generation is the key step for the photocatalytic overall water splitting and considered to be kinetically more challenging than hydrogen generation. Here, an effective water oxidation catalyst of hierarchical FeTiO3-TiO2 hollow spheres are prepared via a two-step sequential solvothermal processes and followed by thermal treatment. The existence of an effective heterointerface and built-in electric field in the surface space charge region in FeTiO3-TiO2 hollow spheres plays a positive role in promoting the separation of photoinduced electron-hole pairs. Surface photovoltage, transient-state photovoltage, fluorescence and electrochemical characterization are used to investigate the transfer process of photoinduced charge carriers. The photogenerated charge carriers in the hierarchical FeTiO3-TiO2 hollow spheres with a proper molar ratio display much higher separation efficiency and longer lifetime than those in the FeTiO3 alone. Moreover, it is suggested that the hierarchical porous hollow structure can contribute to the enhancement of light utilization, surface active sites and material transportation through the framework walls. This specific synergy significantly contributes to the remarkable improvement of the photocatalytic water oxidation activity of the hierarchical FeTiO3-TiO2 hollow spheres under simulated sunlight (AM1.5).

  10. Effect of Sphere Properties on Microstructure and Mechanical Performance of Cast Composite Metal Foams

    Directory of Open Access Journals (Sweden)

    Matias Garcia-Avila

    2015-05-01

    Full Text Available Aluminum-steel composite metal foams (Al-S CMF are manufactured using steel hollow spheres, with a variety of sphere carbon content, surface roughness, and wall porosity, embedded in an Aluminum matrix through gravity casting technique. The microstructural and mechanical properties of the material were studied using scanning electron microscopy, energy dispersive spectroscopy, and quasi-static compressive testing. Higher carbon content and surface roughness in the sphere wall were responsible for an increase in formation of intermetallic phases which had a strengthening effect at lower strain levels, increasing the yield strength of the material by a factor of 2, while higher sphere wall porosity resulted in a decrease on the density of the material and improving its cushioning and ductility maintaining its energy absorption capabilities.

  11. Preparation and electrochemical characteristics of porous hollow spheres of NiO nanosheets as electrodes of supercapacitors

    Science.gov (United States)

    Yu, Wei; Jiang, Xinbing; Ding, Shujiang; Li, Ben Q.

    2014-06-01

    Porous hollow nanospheres (or spherical shells) made of NiO nanosheets are synthesized and tested for the electrochemical performance of the electrodes made of these materials for supercapacitors. Preparation of the NiO sheet hollow spheres starts with synthesis of polystyrene nanospheres with carboxyl groups (CPS), followed by a two-step activation procedure and the subsequent nucleation and growth by electroless deposition of Ni on the CPS core to obtain CPS@Ni core-shell nanoparticles. The CPS core is eliminated and metallic Ni nanoshell is converted into NiO by calcinations at high temperatures. The material properties of as-prepared hollow NiO nanospheres are characterized by TEM, XRD and N2-absorption measurements. The electrochemical characteristics of the electrodes made of these nanostructured NiO materials are determined by the CV and galvanostatic measurements. These electrochemical tests indicate that electrodes made of the NiO nanosheet hollow spheres exhibit an improved reversible capacitance of 600 F g-1 after 1000 cycles at a high current density of 10 A g-1. It is believed that the good electrochemical performance of these electrodes is attributed to the improved OH- transport in the porous network structures associated with the hollow spheres of randomly oriented NiO nanosheets.

  12. Facile Synthesis of Micron-Sized Hollow Silver Spheres as Substrates for Surface-Enhanced Raman Scattering

    Directory of Open Access Journals (Sweden)

    Lixin Xia

    2014-01-01

    Full Text Available A well-designed type of micron-sized hollow silver sphere was successfully synthesized by a simple hard-template method to be used as substrates for surface-enhanced Raman scattering. 4 Å molecular sieves were employed as a removable solid template. [Ag(NH32]+ was absorbed as the precursor on the surface of the molecular sieve. Formaldehyde was selected as a reducing agent to reduce [Ag(NH32]+, resulting in the formation of a micron-sized silver shell on the surface of the 4 Å molecular sieves. The micron-sized hollow silver spheres were obtained by removing the molecular sieve template. SEM and XRD were used to characterize the structure of the micron-sized hollow silver spheres. The as-prepared micro-silver spheres exhibited robust SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA with excitation at 632.8 nm, and the enhancement factor reached ~1.5 × 106. This synthetic process represents a promising method for preparing various hollow metal nanoparticles.

  13. Response Surface Methodology for Design of Porous Hollow Sphere Thermal Insulator

    Science.gov (United States)

    Shohani, Nazanin; Pourmahdian, Saeed; Shirkavand Hadavand, Behzad

    2017-11-01

    In this study, response surface method is used for synthesizing polystyrene (PS) as sacrificial templates and optimizing the particle size. Three factors of initiator, stabilizer concentration and also stirring rate were selected as variable factors. Then, three different concentration of tetraethyl orthosilicate (TEOS) added to reaction media and core-shell structure with PS core and silica shell was developed. Finally, core-shell structure was changed to hollow silica sphere for using as thermal insulator. We observed that increased initiator concentration caused to larger PS particles, increase the stirring rate caused the smaller PS and also with increased the stabilizer concentration obtained that particle size decrease then after 2.5% began to increase. Also the optimum amount of TEOS was found.

  14. Synthesis of nano grade hollow silica sphere via a soft template method.

    Science.gov (United States)

    Tsai, Ming-Shyong; Li, Miao Ju; Yen, Fu-Hsu

    2008-06-01

    The nano grade hollow silica sphere (HSS) was synthesized by a novel soft template method. We found that the precipitate of aluminate had a porous structure that could be the soft template for HSS. After mixing the colloidal silica with the aluminate precipitate, the bubble trapped in this porous structure could form the nano grade HSS. The aluminate precipitate was removed by adjusting the pH of the slurry to approximately 1. The outside diameter, the specific surface, and the mean pore size diameter of the forming HSS were 60-90 nm, 571 m2/g, and 3 nm, respectively. The formed HSS was collected by modifying the surface with Si(OCH3)3CHCH2 (VTMO) and then filtrating the precipitated gel in the n-butanol and ethanol solvent system.

  15. Laser absorption spectroscopy of oxygen confined in highly porous hollow sphere xerogel.

    Science.gov (United States)

    Yang, Lin; Somesfalean, Gabriel; He, Sailing

    2014-02-10

    An Al2O3 xerogel with a distinctive microstructure is studied for the application of laser absorption spectroscopy of oxygen. The xerogel has an exceptionally high porosity (up to 88%) and a large pore size (up to 3.6 µm). Using the method of gas-in-scattering media absorption spectroscopy (GASMAS), a long optical path length (about 3.5m) and high enhancement factor (over 300 times) are achieved as the result of extremely strong multiple-scattering when the light is transmitted through the air-filled, hollow-sphere alumina xerogel. We investigate how the micro-physical feature influences the optical property. As part of the optical sensing system, the material's gas exchange dynamics are also experimentally studied.

  16. New Strategies for Constructing Polymeric Micelles and Hollow Spheres Via Self-Assembly

    Institute of Scientific and Technical Information of China (English)

    Ming Jiang

    2005-01-01

    @@ 1Introduction In recent years, self-assembly of block copolymers leading to micelles in selective solvents, which dissolve only one of the blocks, has developed rapidly because the micelles are very strong candidates for potential applications in advanced technologies. The micelles usually have core-shell structure which are connected by covalent bonds. Based on our long-term research on interpolymer complexation due to hydrogen bonding, where we noticed that the complexation often led to the formation of irregular aggregates, we succeeded recently in developing a series of new approaches to polymeric micelles and hollow spheres via specific intermolecular interactions. As in these approaches, a variety of polymers with interacting groups i.e. homopolymers, random copolymers, graft copolymers as well as low mass compounds (LMC), can be used as building blocks, our research strategies have substantially extended the field of self-assembly.

  17. One-step synthesis of hierarchically porous hybrid TiO2 hollow spheres with high photocatalytic activity

    Science.gov (United States)

    Liu, Ruiping; Ren, Feng; Yang, Jinlin; Su, Weiming; Sun, Zhiming; Zhang, Lei; Wang, Chang-an

    2016-03-01

    Hierarchically porous hybrid TiO2 hollow spheres were solvothermally synthesized successfully by using tetrabutyl titanate as titanium precursor and hydrated metal sulfates as soft templates. The as-prepared TiO2 spheres with hierarchically pore structures and high specific surface area and pore volume consisted of highly crystallized anatase TiO2 nanocrystals hybridized with a small amount of metal oxide from the hydrated sulfate. The proposed hydrated-sulfate assisted solvothermal (HAS) synthesis strategy was demonstrated to be widely applicable to various systems. Evaluation of the hybrid TiO2 hollow spheres for the photo-decomposition of methyl orange (MO) under visible-light irradiation revealed that they exhibited excellent photocatalytic activity and durability.

  18. A hollow sphere soft lithography approach for long-term hanging drop methods.

    Science.gov (United States)

    Lee, Won Gu; Ortmann, Daniel; Hancock, Matthew J; Bae, Hojae; Khademhosseini, Ali

    2010-04-01

    In conventional hanging drop (HD) methods, embryonic stem cell aggregates or embryoid bodies (EBs) are often maintained in small inverted droplets. Gravity limits the volumes of these droplets to less than 50 microL, and hence such cell cultures can only be sustained for a few days without frequent media changes. Here we present a new approach to performing long-term HD methods (10-15 days) that can provide larger media reservoirs in a HD format to maintain more consistent culture media conditions. To implement this approach, we fabricated hollow sphere (HS) structures by injecting liquid drops into noncured poly(dimethylsiloxane) mixtures. These structures served as cell culture chambers with large media volumes (500 microL in each sphere) where EBs could grow without media depletion. The results showed that the sizes of the EBs cultured in the HS structures in a long-term HD format were approximately twice those of conventional HD methods after 10 days in culture. Further, HS cultures showed multilineage differentiation, similar to EBs cultured in the HD method. Due to its ease of fabrication and enhanced features, this approach may be of potential benefit as a stem cell culture method for regenerative medicine.

  19. Controllable synthesis of nitrogen-doped hollow mesoporous carbon spheres using ionic liquids as template for supercapacitors

    Science.gov (United States)

    Chen, Aibing; Li, Yunqian; Liu, Lei; Yu, Yifeng; Xia, Kechan; Wang, Yuying; Li, Shuhui

    2017-01-01

    We have demonstrated a facile and controllable synthesis of monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) using resorcinol/formaldehyde resin as a carbon precursor, tetraethyl orthosilicate as a structure-assistant agent, ionic liquids (ILs) as soft template, partial carbon sources, and nitrogen sources. The sizes and the architectures including hollow and yolk-shell of resultant carbon spheres can be efficiently controlled through the adjustment of the content of ILs. Alkyl chain length of the ILs also has an important effect on the formation of N-HMCSs. With proper alkyl chain length and content of ILs, the resultant N-HMCSs show monodispersed hollow spheres with high surface areas (up to 1158 m2 g-1), large pore volumes (up to 1.70 cm3 g-1), and uniform mesopore size (5.0 nm). Combining the hollow mesoporous structure, high porosity, large surface area, and nitrogen functionality, the as-synthesized N-HMCSs have good supercapacitor performance with good capacitance (up to 159 F g-1) and favorable capacitance retention (88% capacitive retention after 5000 cycles).

  20. Poly(vinyl alcohol)-Assisted Fabrication of Hollow Carbon Spheres/Reduced Graphene Oxide Nanocomposites for High-Performance Lithium-Ion Battery Anodes.

    Science.gov (United States)

    Zhang, Yunqiang; Ma, Qiang; Wang, Shulan; Liu, Xuan; Li, Li

    2018-05-22

    Three-dimensional hollow carbon spheres/reduced graphene oxide (DHCSs/RGO) nanocomposites with high-level heteroatom doping and hierarchical pores are fabricated via a versatile method. Poly(vinyl alcohol) (PVA) that serves as a dispersant and nucleating agent is used as the nonremoval template for synthesizing melamine resin (MR) spheres with abundant heteroatoms, which are subsequently composited with graphene oxide (GO). Use of PVA and implementation of freezing treatment prevent agglomeration of MR spheres within the GO network. Molten KOH is used to achieve the one-step carbonization/activation/reduction for the synthesis of DHCSs/RGO. DHCSs/RGO annealed at 700 °C shows superior discharge capacity of 1395 mA h/g at 0.1 A/g and 606 mA h/g at 5 A/g as well as excellent retentive capacity of 755 mA h/g after 600 cycles at a current density of 2 A/g. An extra CO 2 activation leads to further enhancement of electrochemical performance with outstanding discharge capacity of 1709 mA h/g at 0.1 A/g and 835 mA h/g at 2 A/g after 600 cycles. This work may improve our understanding of the synthesis of graphene-like nanocomposites with hollow and porous carbon architectures and fabrication of high-performance functional devices.

  1. Pseudo-bi-enzyme glucose sensor: ZnS hollow spheres and glucose oxidase concerted catalysis glucose.

    Science.gov (United States)

    Shuai, Ying; Liu, Changhua; Wang, Jia; Cui, Xiaoyan; Nie, Ling

    2013-06-07

    This work creatively uses peroxidase-like ZnS hollow spheres (ZnS HSs) to cooperate with glucose oxidase (GOx) for glucose determinations. This approach is that the ZnS HSs electrocatalytically oxidate the enzymatically generated H2O2 to O2, and then the O2 circularly participates in the previous glucose oxidation by glucose oxidase. Au nanoparticles (AuNPs) and carbon nanotubes (CNTs) are used as electron transfer and enzyme immobilization matrices, respectively. The biosensor of glucose oxidase-carbon nanotubes-Au nanoparticles-ZnS hollow spheres-gold electrode (GOx-CNT-AuNPs-ZnS HSs-GE) exhibits a rapid response, a low detection limit (10 μM), a wide linear range (20 μM to 7 mM) as well as good anti-interference, long-term longevity and reproducibility.

  2. Synthesis and characterization of hollow α-Fe2O3 sub-micron spheres prepared by sol–gel

    International Nuclear Information System (INIS)

    León, Lizbet; Bustamante, Angel; Osorio, Ana; Olarte, G. S.; Santos Valladares, Luis De Los; Barnes, Crispin H. W.; Majima, Yutaka

    2011-01-01

    In this work we report the preparation of magnetic hematite hollow sub-micron spheres (α-Fe 2 O 3 ) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO 3 ) 3 ·9H 2 O) particles in citric acid solution by following the sol–gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180°C resulted in an amorphous phase, without iron oxide formation. Annealing at 250°C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400°C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600°C. The characterization was performed by X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and scanning electron microscopy (SEM).

  3. Nitrogen and phosphorus co-doped carbon hollow spheres derived from polypyrrole for high-performance supercapacitor electrodes

    Science.gov (United States)

    Lv, Bingjie; Li, Peipei; Liu, Yan; Lin, Shanshan; Gao, Bifen; Lin, Bizhou

    2018-04-01

    Nitrogen and phosphorus co-doped carbon hollow spheres (NPCHSs) have been prepared by a carbonization and subsequent chemical activation route using dehydrated polypyrrole hollow spheres as the precursor and KOH as the activating agent. NPCHSs are interconnected into a unique 3D porous network, which endows the as-prepared carbon to exhibit a large specific surface area of 1155 m2 g-1 and a high specific capacitance of 232 F g-1 at a current density of 1 A g-1. The as-obtained NPCHSs present a high-level heteroatom doping with N, O and P contents of 11.4, 6.7 and 3.5 wt%, respectively. The capacitance of NPCHSs has been retained at 89.1% after 5000 charge-discharge cycles at a relatively high current density of 5 A g-1. Such excellent performance suggests that NPCHSs are attractive electrode candidates for electrical double layer capacitors.

  4. L-cysteine-assisted synthesis of hierarchical NiS2 hollow spheres supported carbon nitride as photocatalysts with enhanced lifetime

    Science.gov (United States)

    Zhu, Chengzhang; Jiang, Zhifeng; Chen, Linlin; Qian, Kun; Xie, Jimin

    2017-03-01

    Novel hierarchical NiS2 hollow spheres modified by graphite-like carbon nitride were prepared using a facile L-cysteine-assisted solvothermal route. The NiS2/g-C3N4 composites exhibited excellent photocatalytic efficiency in rhodamine B, methyl orange and ciprofloxacin degradation as compared to single g-C3N4 and NiS2, which could be due to the synergistic effects of the unique hollow sphere-like structure, strong visible-light absorption and increased separation rate of the photoinduced electron-hole pairs at the intimate interface of heterojunctions. A suitable combination of g-C3N4 with NiS2 showed the best photocatalytic performance. In addition, an electron spin resonance and trapping experiment demonstrated that the photogenerated hydroxyl radicals and superoxide radicals were the two main photoactive species in photocatalysis. A possible photocatalytic mechanism of NiS2/g-C3N4 composites under visible light irradiation is also proposed. The strategy presented here can be extended to a general strategy for constructing 3D/2D heterostructured photocatalysts for broad applications in photocatalysis.

  5. Three-dimensional graphene-polyaniline hybrid hollow spheres by layer-by-layer assembly for application in supercapacitor

    International Nuclear Information System (INIS)

    Luo, Jing; Ma, Qiang; Gu, Huahao; Zheng, Yuan; Liu, Xiaoya

    2015-01-01

    Highlights: •A graphene-polyaniline (GR-PANI) hybrid hollow sphere is fabricated by layer-by-layer (LBL) assembly technique. •The GR-PANI hollow sphere has higher specific capacitance than stacked GR-PANI LBL film. •64% of its initial capacitance is maintained with the current density increased from 0.5 to 20 A g −1 . •A high capacity retention rate of 83% after 1000 cycles can be achieved. -- Abstract: A novel kind of three-dimensional graphene-polyaniline hybrid hollow sphere (RGO-PANI HS) has been prepared via layer-by-layer (LBL) assembly of negatively-charged reduced graphene oxide (RGO) and positively charged polyaniline (PANI) on polystyrene (PS) microsphere, followed by the removal of the PS template. The hollow structure of the obtained RGO-PANI HS is confirmed by transmission electron microscopy (TEM). When used as the electrode materials for supercapacitor, the specific capacitance of the RGO-PANI HS reaches 381 F/g at a current density of 4.0 A/g, which is much higher than 251 F/g of the stacked RGO-PANI LBL film. The higher specific capacitance of RGO-PANI HS should be attributed to its unique hollow structure which provides a larger accessible surface area and facilitate the charge and ion transport. In addition, its specific capacitance can be facilely tailored by changing the assembly cycle number. Furthermore, good cycling stability is also demonstrated with 83% of the original capacitance value maintained after 1000 charging/discharging cycles

  6. Broadband micro-Michelson interferometer with multi-optical-path beating using a sphered-end hollow fiber.

    Science.gov (United States)

    Chen, Nan-Kuang; Lu, Kuan-Yi; Shy, Jow-Tsong; Lin, Chinlon

    2011-06-01

    We demonstrate a high-sensitivity broadband (1250-1650 nm) fiber micro-Michelson interferometer using a single-mode fiber end-spliced with a sphered-end hollow-core fiber. The hollow core is slightly smaller than the solid core of a single-mode fiber, so the fractional power of the core mode is converted into cladding modes. The excited cladding modes propagate at distinct optical paths along the hollow-core fiber and have individual foci outside the spherical lens. The reflected core mode, generated at the solid core-air interface, and the reflected cladding modes, generated at external material, interfere with each other to produce beating in the interference signals. © 2011 Optical Society of America

  7. Fabrication of hollow-sphere films of wurtzite CuInS{sub 2} on copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Shuijin, E-mail: shjlei@ncu.edu.cn [School of Materials Science and Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Wang, Chunying [School of Materials Science and Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Huang, Qiang [School of Electromechanical Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China); Liu, Lei; Ge, Yang; Tang, Qingliu; Cheng, Baochang; Xiao, Yanhe; Zhou, Lang [School of Materials Science and Engineering, Nanchang University, Nanchang, Jiangxi 330031 (China)

    2013-12-16

    As important semiconductors, I–III–VI{sub 2} compounds have attracted wide attention, among which the wurtzite structured CuInS{sub 2} has been the research focus due to its metastable phase. In this paper, the wurtzite CuInS{sub 2} hollow-sphere films have been successfully prepared on copper substrate in a self-designed solvothermal detached system. The films of Cu(OH){sub 2} one-dimensional nanostructure arrays and thioacetamide were used as the precursors and triethylene glycol was used as the solvent. Experiments showed that the amount of indium trichloride played a determinative role in the final morphology of the products. Meanwhile, the one-dimensional nanostructure arrays and the detached solvothermal system have great influences on the crystal shape as well. Based on the experimental results, a possible formation mechanism for the CuInS{sub 2} hollow spheres was also proposed. The UV–Vis absorption spectrum showed a broad absorption over the entire visible light and extending into the near-infrared region and presented the band gap of 1.53 eV for the as-prepared wurtzite CuInS{sub 2}, which indicates the potential applications in solar cells. - Highlights: • A self-designed detached system along with solvothermal treatment was developed. • Wurtzite CuInS{sub 2} hollow-sphere films were successfully fabricated on Cu substrate. • The detached system and InCl{sub 3} usage were crucial for the hollow spheres. • The broadband absorption and 1.53 eV band-gap indicates its potentials in PV.

  8. Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

    OpenAIRE

    Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

    2017-01-01

    Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hol...

  9. Lithium-ion storage capacitors achieved by CVD graphene/TaC/Ta-wires and carbon hollow spheres

    International Nuclear Information System (INIS)

    Zhao, Liwei; Li, Hongji; Li, Mingji; Xu, Sheng; Li, Cuiping; Qu, Changqing; Zhang, Lijun; Yang, Baohe

    2016-01-01

    Highlights: • Graphene/TaC/Ta wire electrode was prepared by CVD. • Carbon hollow spheres as a solid electrolyte were prepared by hydrothermal. • Specific capacitance of assembled capacitor reached 593 F g −1 at 10 A g −1 . • The capacitor provided high energy and power densities (132 W h kg −1 /3.17 kW kg −1 ). • The hybrid capacitor also exhibited a high stability during long endurance tests. - Abstract: Lithium-ion storage capacitors were assembled using graphene/tantalum carbide/tantalum wire electrodes and carbon hollow spheres as electrolyte. The graphene/tantalum carbide layers were prepared by electron-assisted hot filament chemical vapor deposition; the carbon hollow spheres were synthesized by hydrothermal reaction and pyrolysis treatment. The specific capacitance of the capacitor was 593 F g −1 at a current density of 10 A g −1 . The capacitor showed excellent cycling stability, retaining 91.2% of its initial capacitance after 8000 cycles. Moreover, the capacitor provided a high specific energy density of 132 W h kg −1 at a high power density of 3.17 kW kg −1 . The high energy density is attributed to the widened operation window ranging from 0 to 3.0 V. The graphene layer of the electrode and carbon hollow spheres in electrolyte synergistic affect influence on the electrochemical performance of the capacitor are discussed. In addition, the use of a low-cost lithium salt, lithium chloride, is also featured in this paper.

  10. Instantaneous, Simple, and Reversible Revealing of Invisible Patterns Encrypted in Robust Hollow Sphere Colloidal Photonic Crystals.

    Science.gov (United States)

    Zhong, Kuo; Li, Jiaqi; Liu, Liwang; Van Cleuvenbergen, Stijn; Song, Kai; Clays, Koen

    2018-05-04

    The colors of photonic crystals are based on their periodic crystalline structure. They show clear advantages over conventional chromophores for many applications, mainly due to their anti-photobleaching and responsiveness to stimuli. More specifically, combining colloidal photonic crystals and invisible patterns is important in steganography and watermarking for anticounterfeiting applications. Here a convenient way to imprint robust invisible patterns in colloidal crystals of hollow silica spheres is presented. While these patterns remain invisible under static environmental humidity, even up to near 100% relative humidity, they are unveiled immediately (≈100 ms) and fully reversibly by dynamic humid flow, e.g., human breath. They reveal themselves due to the extreme wettability of the patterned (etched) regions, as confirmed by contact angle measurements. The liquid surface tension threshold to induce wetting (revealing the imprinted invisible images) is evaluated by thermodynamic predictions and subsequently verified by exposure to various vapors with different surface tension. The color of the patterned regions is furthermore independently tuned by vapors with different refractive indices. Such a system can play a key role in applications such as anticounterfeiting, identification, and vapor sensing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effects of microporosity on the elasticity and yielding of thin-walled metallic hollow spheres

    International Nuclear Information System (INIS)

    Song, Jinliang; Sun, Quansheng; Yang, Zhenning; Luo, Shengmin; Xiao, Xianghui; Arwade, Sanjay R.; Zhang, Guoping

    2017-01-01

    Knowledge of the mechanical properties of porous metallic hollow spheres (MHS) thin wall is of key importance for understanding the engineering performance of both individual ultralight MHS and the innovative MHS-based bulk foams. This paper presents the first integrated experimental and numerical study to determine the elasticity and yielding of the porous MHS wall and their dependence on its microporosity. Nanoindentation was used to probe the Young's modulus and hardness of the nonporous MHS wall material, and synchrotron X-ray computed tomography (XCT) conducted to obtain its porous microstructure and pore morphology. Three-dimensional finite element modeling was performed to obtain the mechanical response of microcubes with varying porosity trimmed from the XCT-derived real digital model of the porous MHS wall. Results show that both the Young's modulus and yield strength of the porous wall decrease nonlinearly with increasing porosity, and their relationships follow the same format of a power law function and agree well with prior experimental results. The empirical relations also reflect certain features of pore morphology, such as pore connectivity and shape. These findings can shed lights on the design, manufacturing, and modeling of individual MHS and MHS-based foams.

  12. Effects of microporosity on the elasticity and yielding of thin-walled metallic hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jinliang [Department of Civil Engineering, Northeast Forestry University, Harbin 150040 (China); Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01003 (United States); Sun, Quansheng [Department of Civil Engineering, Northeast Forestry University, Harbin 150040 (China); Yang, Zhenning; Luo, Shengmin [Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01003 (United States); Xiao, Xianghui [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Arwade, Sanjay R. [Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01003 (United States); Zhang, Guoping, E-mail: zhangg@umass.edu [Department of Civil and Environmental Engineering, University of Massachusetts Amherst, Amherst, MA 01003 (United States)

    2017-03-14

    Knowledge of the mechanical properties of porous metallic hollow spheres (MHS) thin wall is of key importance for understanding the engineering performance of both individual ultralight MHS and the innovative MHS-based bulk foams. This paper presents the first integrated experimental and numerical study to determine the elasticity and yielding of the porous MHS wall and their dependence on its microporosity. Nanoindentation was used to probe the Young's modulus and hardness of the nonporous MHS wall material, and synchrotron X-ray computed tomography (XCT) conducted to obtain its porous microstructure and pore morphology. Three-dimensional finite element modeling was performed to obtain the mechanical response of microcubes with varying porosity trimmed from the XCT-derived real digital model of the porous MHS wall. Results show that both the Young's modulus and yield strength of the porous wall decrease nonlinearly with increasing porosity, and their relationships follow the same format of a power law function and agree well with prior experimental results. The empirical relations also reflect certain features of pore morphology, such as pore connectivity and shape. These findings can shed lights on the design, manufacturing, and modeling of individual MHS and MHS-based foams.

  13. Hollow carbon spheres with encapsulation of Co3O4 nanoparticles as anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Zhan Liang; Wang Yanli; Qiao Wenming; Ling, Licheng; Yang Shubin

    2012-01-01

    Graphical abstract: Hollow carbon spheres with encapsulation of Co 3 O 4 nanoparticles were synthesized. As anode materials for lithium ion battery, the reversible capacity of obtained electrode is as high as 732 mAh g −1 at 74 mA g −1 and 500 mAh g −1 at 744 mA g −1 . - Abstract: Based on the high theoretical capacity of Co 3 O 4 for lithium storage, a noval type of monodisperse hollow carbon spheres with encapsulation of Co 3 O 4 nanoparticles (HCSE-Co 3 O 4 ) were designed and synthesized. The monodisperse hollow carbon spheres not only can provide enough void volume to accommodate the volume change of encapsulated Co 3 O 4 nanoparicles, but also can prevent the formation of solid electrolyte interface (SEI) films on the surface of Co 3 O 4 nanoparticles and following direct contact of Co and SEI films upon lithium extraction. The HCSE-Co 3 O 4 electrode exhibit highly reversible capacity, excellent cycle performance and rate capability attributed to the unique structure. The reversible capacity of HCSE-Co 3 O 4 electrode is as high as 500 mAh g −1 at a current density of 744 mA g −1 , while that of bare Co 3 O 4 electrode is only around 80 mAh g −1 .

  14. High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

    International Nuclear Information System (INIS)

    Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong

    2016-01-01

    Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m 2 /g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.

  15. High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong, E-mail: dszhang@shu.edu.cn

    2016-04-30

    Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m{sup 2}/g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.

  16. Low temperature synthesis and photocatalytic property of perovskite-type LaCoO{sub 3} hollow spheres

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Shasha [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Niu, Helin, E-mail: niuhelin@ahu.edu.cn [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Tao, Zhiyin; Song, Jiming; Mao, Changjie; Zhang, Shengyi [School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039 (China); Chen, Changle, E-mail: changle@ustc.edu.cn [CAS Key Laboratory of Soft Matter Chemistry and Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026 (China); Wang, Dong [Department of Bio-Health Technology, College of Biomedical Science, Kangwon National University, Chuncheon, Gangwon-Do 200-701 (Korea, Republic of)

    2013-11-05

    Highlights: •Hollow perovskite-type LaCoO{sub 3} is fabricated by green colloidal template method. •Carbonaceous colloids acted as templates and offered internal heat source. •The calcination temperature to form perovskite-type LaCoO{sub 3} was dropped to 550 °C. •The photocatalytic properties were studied upon UV irradiation. •Hollow perovskite-type LaCoO{sub 3} shows excellent photocatalytic activity on dyes. -- Abstract: Hollow perovskite-type LaCoO{sub 3} was successfully fabricated by surface-ion adsorption method utilizing the carbonaceous colloids as template under relatively low calcination temperature. Carbonaceous colloids not only acted as templates but also offered internal heat source during calcination process. The impact of calcined temperature and time on the structure and morphology of the product were studied and the possible formation process of perovskite-type LaCoO{sub 3} hollow spheres was illustrated. The obtained product was characterized by SEM, TEM, XRD, TG-DSC, ICP-OES, BET and UV–visible absorption spectra. The photocatalytic activities for degradation of methylene blue, methyl orange and neutral red were tested. The good photocatalytic degradation activity of the three different dyes and the band gap of 2.07 eV make it a promising candidate material for photocatalytic applications.

  17. Low temperature synthesis and photocatalytic property of perovskite-type LaCoO3 hollow spheres

    International Nuclear Information System (INIS)

    Fu, Shasha; Niu, Helin; Tao, Zhiyin; Song, Jiming; Mao, Changjie; Zhang, Shengyi; Chen, Changle; Wang, Dong

    2013-01-01

    Highlights: •Hollow perovskite-type LaCoO 3 is fabricated by green colloidal template method. •Carbonaceous colloids acted as templates and offered internal heat source. •The calcination temperature to form perovskite-type LaCoO 3 was dropped to 550 °C. •The photocatalytic properties were studied upon UV irradiation. •Hollow perovskite-type LaCoO 3 shows excellent photocatalytic activity on dyes. -- Abstract: Hollow perovskite-type LaCoO 3 was successfully fabricated by surface-ion adsorption method utilizing the carbonaceous colloids as template under relatively low calcination temperature. Carbonaceous colloids not only acted as templates but also offered internal heat source during calcination process. The impact of calcined temperature and time on the structure and morphology of the product were studied and the possible formation process of perovskite-type LaCoO 3 hollow spheres was illustrated. The obtained product was characterized by SEM, TEM, XRD, TG-DSC, ICP-OES, BET and UV–visible absorption spectra. The photocatalytic activities for degradation of methylene blue, methyl orange and neutral red were tested. The good photocatalytic degradation activity of the three different dyes and the band gap of 2.07 eV make it a promising candidate material for photocatalytic applications

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

    Science.gov (United States)

    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.

  19. Enhanced photocatalytic performance and degradation pathway of Rhodamine B over hierarchical double-shelled zinc nickel oxide hollow sphere heterojunction

    Science.gov (United States)

    Zhang, Ying; Zhou, Jiabin; Cai, Weiquan; Zhou, Jun; Li, Zhen

    2018-02-01

    In this study, hierarchical double-shelled NiO/ZnO hollow spheres heterojunction were prepared by calcination of the metallic organic frameworks (MOFs) as a sacrificial template in air via a one-step solvothermal method. Additionally, the photocatalytic activity of the as-prepared samples for the degradation of Rhodamine B (RhB) under UV-vis light irradiation were also investigated. NiO/ZnO microsphere comprised a core and a shell with unique hierarchically porous structure. The photocatalytic results showed that NiO/ZnO hollow spheres exhibited excellent catalytic activity for RhB degradation, causing complete decomposition of RhB (200 mL of 10 g/L) under UV-vis light irradiation within 3 h. Furthermore, the degradation pathway was proposed on the basis of the intermediates during the photodegradation process using liquid chromatography analysis coupled with mass spectroscopy (LC-MS). The improvement in photocatalytic performance could be attributed to the p-n heterojunction in the NiO/ZnO hollow spheres with hierarchically porous structure and the strong double-shell binding interaction, which enhances adsorption of the dye molecules on the catalyst surface and facilitates the electron/hole transfer within the framework. The degradation mechanism of pollutant is ascribed to the hydroxyl radicals (rad OH), which is the main oxidative species for the photocatalytic degradation of RhB. This work provides a facile and effective approach for the fabrication of porous metal oxides heterojunction with high photocatalytic activity and thus can be potentially used in the environmental purification.

  20. Experimental stress analysis of large plastic deformations in a hollow sphere deformed by impact against a concrete block

    Science.gov (United States)

    Morris, R. E.

    1973-01-01

    An experimental plastic strain measurement system is presented for use on the surface of high velocity impact test models. The system was used on a hollow sphere tested in impact against a reinforced concrete block. True strains, deviatoric stresses, and true stresses were calculated from experimental measurements. The maximum strain measured in the model was small compared to the true failure strain obtained from static tensile tests of model material. This fact suggests that a much greater impact velocity would be required to cause failure of the model shell structure.

  1. Solvent-induced synthesis of nitrogen-doped hollow carbon spheres with tunable surface morphology for supercapacitors

    Science.gov (United States)

    Liu, Feng; Yuan, Ren-Lu; Zhang, Ning; Ke, Chang-Ce; Ma, Shao-Xia; Zhang, Ru-Liang; Liu, Lei

    2018-04-01

    Nitrogen doped hollow carbon spheres (NHCSs) with tunable surface morphology have been prepared through one-pot carbonization method by using melamine-formaldehyde spheres as template and resorcinol-based resin as carbon precursor in ethanol-water solution. Well-dispersed NHCSs with particle size of 800 nm were obtained and the surface of NHCSs turn from smooth to tough, wrinkled, and finally concave by increasing the ethanol concentration. The fabricated NHCSs possessed high nitrogen content (3.99-4.83%) and hierarchical micro-dual mesoporous structure with surface area range of 265-405 m2 g-1 and total pore volume of 0.18-0.29 cm3 g-1, which contributed to high specific capacitance, excellent rate capability and long cycle life.

  2. Hierarchical NiO-SiO2 composite hollow microspheres with enhanced adsorption affinity towards Congo red in water.

    Science.gov (United States)

    Lei, Chunsheng; Zhu, Xiaofeng; Zhu, Bicheng; Yu, Jiaguo; Ho, Wingkei

    2016-03-15

    Hollow microspheres and hierarchical porous nanostructured materials with desired morphologies have gained remarkable attention for their potential applications in environmental technology. In this study, NiO-SiO2 hollow microspheres were prepared by co-precipitation with SiO2 and nickel salt as precursors, followed by dipping in alkaline solution and calcination. The samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption, and X-ray photoelectron spectroscopy. The synthesized hollow spheres were composed of a SiO2 shell and hierarchical porous NiO nanosheets on the surface. Adsorption experiments suggested that NiO-SiO2 composite particles were powerful adsorbents for removal of Congo red from water, with a maximum adsorption capacity of 204.1 mg/g. The high specific surface areas, hollow structures, and hierarchical porous surfaces of the hollow composite particles are suitable for various applications, including adsorption of pollutants, chemical separation, and water purification. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Uniform hollow Fe3O4 spheres prepared by template-free solvothermal method as anode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhang Jingjing; Yao Yu; Huang Tao; Yu Aishui

    2012-01-01

    Graphical abstract: Unique hollow Fe 3 O 4 spheres assembled by Fe 3 O 4 nanoparticles prepared by a simple template-free solvothermal reaction are tested as anode material for lithium-ion batteries. The results show that the material delivers reversible specific capacities of 870 mA h g −1 even after 50 cycles at 100 mA g −1 and 836 mA h g −1 at 500 mA g −1 . The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability. Highlights: ► Uniform hollow Fe 3 O 4 spheres were prepared by a template-free solvothermal method. ► The hollow Fe 3 O 4 spheres have the capacity of 870 mA h g −1 at 50th cycle. ► The specific capacity can be well maintained at a large current density. ► The hollow Fe 3 O 4 spheres exhibit enhanced rate capability. ► Electrochemical performance of hollow Fe 3 O 4 spheres is better than Fe 3 O 4 powders. - Abstract: Unique hollow Fe 3 O 4 spheres are prepared by a simple template-free solvothermal reaction. In the reaction, ethylene glycol (EG) and polyvinylpyrrolidone (PVP) serve as the reducing agent and surface stabilizer, respectively. NH 4 Ac plays the role of the structure-directing agent, which combines with the Ostwald ripening process, resulting in the favored formation of hollow structures. The morphologies and structures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The hollow Fe 3 O 4 spheres exhibit excellent cycling and rate performance as anode material for lithium-ion batteries, delivering reversible specific capacities of 870 mA h g −1 even after 50 cycles at 100 mA g −1 and 836 mA h g −1 at 500 mA g −1 . The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability.

  4. Fabrication of α-Fe{sub 2}O{sub 3}/TiO{sub 2} bi-functional composites with hierarchical and hollow structures and their application in water treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yinhui, E-mail: lillian09281@hotmail.com; Zhang, Na; Chen, Jianxin, E-mail: chjx2000@126.com; Li, Ruijuan; Li, Liang; Li, Kunyu [Hebei University of Technology, School of Marine Science and Engineering, Engineering Research Center of Seawater Utilization Technology, Ministry of Education (China)

    2016-02-15

    The α-Fe{sub 2}O{sub 3}/TiO{sub 2} bi-functional composites with hierarchical and hollow structures are fabricated through a hydrothermal route. The adsorption performance and photocatalytic activity of the composites towards Pb{sup 2+} are investigated in this work. Different adsorption kinetics models and equilibrium models are used to explore the adsorption behavior of hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres. Experimental data show that adsorption kinetics of the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres can be fitted well by the pseudo-second-order model, while the isothermal data can be perfectly described by the Langmuir adsorption model. The maximum adsorption capacity of the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres is 32.36 mg g{sup −1}. Moreover, the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres possess photocatalytic oxidation character under simulated solar light irradiation. The results demonstrate that the hierarchical α-Fe{sub 2}O{sub 3}/TiO{sub 2} hollow spheres, as effective and cheap materials, can be applied to the removal of heavy metal ions from wastewater.

  5. Bubble template synthesis of Sn2Nb2O7 hollow spheres for enhanced visible-light-driven photocatalytic hydrogen production.

    Science.gov (United States)

    Zhou, Chao; Zhao, Yufei; Bian, Tong; Shang, Lu; Yu, Huijun; Wu, Li-Zhu; Tung, Chen-Ho; Zhang, Tierui

    2013-10-28

    Hierarchical Sn2Nb2O7 hollow spheres were prepared for the first time via a facile hydrothermal route using bubbles generated in situ from the decomposition of urea as soft templates. The as-obtained hollow spheres with a large specific surface area of 58.3 m(2) g(-1) show improved visible-light-driven photocatalytic H2 production activity in lactic acid aqueous solutions, about 4 times higher than that of the bulk Sn2Nb2O7 sample prepared by a conventional high temperature solid state reaction method.

  6. Rational synthesis of graphene-encapsulated uniform MnMoO4 hollow spheres as long-life and high-rate anodes for lithium-ion batteries.

    Science.gov (United States)

    Wei, Huaixin; Yang, Jun; Zhang, Yufei; Qian, Yong; Geng, Hongbo

    2018-03-29

    In this manuscript, the graphene-encapsulated MnMoO 4 hollow spheres (MnMoO 4 @G) synthesized by an effective strategy were reported. Benefiting from the intriguing hybrid architecture of hollow structure and conductive graphene network, the MnMoO 4 @G composite displays superior electrochemical performance with high specific capacity of 1142 mA h g -1 , high reversible cycling stability of 921 mA h g -1 at a current density of 100 mA g -1 after 70 cycles, and stable rate performance (around 513 mA h g -1 at a current density of 4.0 A g -1 ). The remarkable battery performance can be attributed to the rational design of the architecture, which not only ensures the fast transport of electrons and lithium ions within the electrode material, but also effectively relax the stress induced by the insertion/extraction of lithium ions. This facile synthetic method can extend to other transition metal oxides with large volume excursions and poor electric conductivity and promotes the development of transition metal oxides as high-performance LIB anode material. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. High photocatalytic activity of hierarchical SiO2@C-doped TiO2 hollow spheres in UV and visible light towards degradation of rhodamine B.

    Science.gov (United States)

    Zhang, Ying; Chen, Juanrong; Hua, Li; Li, Songjun; Zhang, Xuanxuan; Sheng, Weichen; Cao, Shunsheng

    2017-10-15

    Ongoing research activities are targeted to explore high photocatalytic activity of TiO 2 -based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO 2 @C-doped TiO 2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO 2 , the preparation of the sandwich-like CPS@SiO 2 @CPS particles, and formation of outer TiO 2 . After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO 2 @C-doped TiO 2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO 2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO 2 -based photocatalysts due to doping. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Hollow SnO2@Co3O4 core-shell spheres encapsulated in three-dimensional graphene foams for high performance supercapacitors and lithium-ion batteries

    Science.gov (United States)

    Zhao, Bo; Huang, Sheng-Yun; Wang, Tao; Zhang, Kai; Yuen, Matthew M. F.; Xu, Jian-Bin; Fu, Xian-Zhu; Sun, Rong; Wong, Ching-Ping

    2015-12-01

    Hollow SnO2@Co3O4 spheres are fabricated using 300 nm spherical SiO2 particles as template. Then three-dimensional graphene foams encapsulated hollow SnO2@Co3O4 spheres are successfully obtained through self-assembly in hydrothermal process from graphene oxide nanosheets and metal oxide hollow spheres. The three-dimensional graphene foams encapsulated architectures could greatly improve the capacity, cycling stability and rate capability of hollow SnO2@Co3O4 spheres electrodes due to the highly conductive networks and flexible buffering matrix. The three-dimensional graphene foams encapsulated hollow SnO2@Co3O4 spheres are promising electrode materials for supercapacitors and lithium-ion batteries.

  9. Hollow Spheres of Iron Carbide Nanoparticles Encased in Graphitic Layers as Oxygen Reduction Catalysts

    DEFF Research Database (Denmark)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei

    2014-01-01

    Nonprecious metal catalysts for the oxygen reduction reaction are the ultimate materials and the foremost subject for low‐temperature fuel cells. A novel type of catalysts prepared by high‐pressure pyrolysis is reported. The catalyst is featured by hollow spherical morphologies consisting...

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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: → CdS hollow nanospheres with diameters of 40-150 nm were synthesized. → Nanoparticles were characterized by UV/Vis and photoluminescence. → Nanospheres are composed of smaller nanocrystals with the average size of 6.8 nm. → The band gap energy of the CdS nanoparticles is higher than its bulk value.

  11. Preparation of hollow mesoporous carbon spheres and their performances for electrochemical applications

    Science.gov (United States)

    Ariyanto, T.; Zhang, G. R.; Kern, A.; Etzold, B. J. M.

    2018-03-01

    Hollow carbon materials have received intensive attention for energy storage/conversion applications due to their attractive properties of high conductivity, high surface area, large void and short diffusion pathway. In this work, a novel hollow mesoporous material based on carbide-derived carbon (CDC) is presented. CDC is a new class of carbon material synthesized by the selective extraction of metals from metal carbides. With a two-stage extraction procedure of carbides with chlorine, firstly hybrid core-shell carbon particles were synthesized, i.e. mesoporous/graphitic carbon shells covering microporous/amorphous carbon cores. The amorphous cores were then selectively removed from particles by a careful oxidative treatment utilizing its low thermal characters while the more stable carbon shells remained, thus resulting hollow particles. The characterization methods (e.g. N2 sorption, Raman spectroscopy, temperature-programmed oxidation and SEM) proved the successful synthesis of the aspired material. In electric double-layer capacitor (EDLC) testing, this novel hollow core material showed a remarkable enhancement of EDLC’s rate handling ability (75% at a high scan rate) with respect to an entirely solid-mesoporous material. Furthermore, as a fuel cell catalyst support the material showed higher Pt mass activity (a factor of 1.8) compared to a conventional carbon support for methanol oxidation without noticeably decreasing activity in a long-term testing. Therefore, this carbon nanostructure shows great promises as efficient electrode materials for energy storage and conversion systems.

  12. A novel enzymatic glucose sensor based on Pt nanoparticles-decorated hollow carbon spheres-modified glassy carbon electrode

    Science.gov (United States)

    Luhana, Charles; Bo, Xiang-Jie; Ju, Jian; Guo, Li-Ping

    2012-10-01

    A new glucose biosensor was developed based on hollow carbon spheres decorated with platinum nanoparticles (Pt/HCSs)-modified glassy carbon electrode immobilized with glucose oxidase (GOx) with the help of Nafion. The Pt nanoparticles were well dispersed on the HCSs with an average size of 2.29 nm. The detection of glucose was achieved via electrochemical detection of the enzymatically liberated H2O2 at +0.5 V versus Ag/AgCl at physiologic pH of 7.4. The Pt/HCSs-modified electrode exhibited excellent electrocatalytic activities toward both the oxidation and reduction of H2O2. The glucose biosensor showed good electrocatalytic performance in terms of high sensitivity (4.1 μA mM-1), low detection limit (1.8 μM), fast response time tested with this biosensor and a good recovery was achieved for the two spiked serum samples.

  13. Nanometric onion-like hollow spheres in laser synthesized boron nitride ultrafine powder

    Energy Technology Data Exchange (ETDEWEB)

    Boulanger, L; Willaime, F [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Technologies Avancees; Cauchetier, M [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Recherche sur l` Etat Condense, les Atomes et les Molecules

    1994-12-31

    TEM observations of ultra-fine B Cl{sub 3}-N H{sub 3} powders elaborated by an innovative method, laser pyrolysis, are presented. The resulting microstructures in the as received state and after thermal treatments show small nanometric scale configurations close to the ones met with carbon, such as an hollowed configuration of onions but at a much smaller scale than with carbon. 3 figs., 3 refs.

  14. Research Update: Facile synthesis of CoFe2O4 nano-hollow spheres for efficient bilirubin adsorption

    Science.gov (United States)

    Rakshit, Rupali; Pal, Monalisa; Chaudhuri, Arka; Mandal, Madhuri; Mandal, Kalyan

    2015-11-01

    Herein, we report an unprecedented bilirubin (BR) adsorption efficiency of CoFe2O4 (CFO) nanostructures in contrast to the commercially available activated carbon and resin which are generally used for haemoperfusion and haemodialysis. We have synthesized CFO nanoparticles of diameter 100 nm and a series of nano-hollow spheres of diameter 100, 160, 250, and 350 nm using a simple template free solvothermal technique through proper variation of reaction time and capping agent, oleylamine (OLA), respectively, and carried out SiO2 coating by employing Stöber method. The comparative BR adsorption study of CFO and SiO2 coated CFO nanostructures indicates that apart from porosity and hollow configuration of nanostructures, the electrostatic affinity between anionic carboxyl group of BR and cationic amine group of OLA plays a significant role in adsorbing BR. Finally, we demonstrate that the BR adsorption capacity of the nanostructures can be tailored by varying the morphology as well as size of the nanostructures. We believe that our developed magnetic nanostructures could be considered as a potential material towards therapeutic applications against hyperbilirubinemia.

  15. Micelles driven magnetite (Fe{sub 3}O{sub 4}) hollow spheres and a study on AC magnetic properties for hyperthermia application

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Madhuri Mandal, E-mail: madhuri@bose.res.in [Department of Condensed Matter Physics and Material Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Dey, Chaitali [Department of Condensed Matter Physics and Material Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); CRNN, University of Calcutta, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Bandyopadhyay, Ayan [CRNN, University of Calcutta, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Sarkar, Debasish [Department of Condensed Matter Physics and Material Science, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106 (India); Ahir, Manisha [CRNN, University of Calcutta, Block JD, Sector III, Salt Lake, Kolkata 700106 (India)

    2016-11-01

    Here we have discussed about designing the magnetic particles for hyperthermia therapy and done some studies in this direction. We have used oleylamine micelles as template to synthesize hollow–nanospheres (HNS) of magnetite by solvo-thermal technique. We have shown that oleylamine plays an important role to generate hollow particles. Structural analysis was done by XRD measurement and morphological measurements like SEM and TEM was performed to confirm the shape and size of hollow sphere particles. The detail magnetic measurements give an idea about the application of these HNS for magnetic heating in hyperthermia therapy. In vitro cytotoxicity studies reveal that tolerable dose rate for these particles can be significantly high and particles are non-toxic in nature. Being hollow in structure and magnetic in nature such materials will also be useful in other application fields like in drug delivery, drug release, arsenic and heavy metal removal by adsorption technique, magnetic separation etc. - Graphical abstract: Oleylamine micelles driven easy synthesis of hollow nanosphere (HNS) magnetite for hyperthermia therapy. - Highlights: • We have reported a new method of synthesis of hollow spheres of magnetite using micelles as model core and removal of micelles evolve the hollow like structure by relocating the core particles to the edge one. • Size can be controlled by varying the micellar concentration. • The detail magnetic measurements give an idea of applicability of these nano hollow spheres (NHS) in hyperthermia therapy. • Cyto-toxicity study reveals that these particles are highly biofriendly and dose rate can be increased upto a significant amount.

  16. Design and Synthesis of Hierarchical SiO2@C/TiO2 Hollow Spheres for High-Performance Supercapacitors.

    Science.gov (United States)

    Zhang, Ying; Zhao, Yan; Cao, Shunsheng; Yin, Zhengliang; Cheng, Li; Wu, Limin

    2017-09-06

    TiO 2 has been widely investigated as an electrode material because of its long cycle life and good durability, but the relatively low theoretical capacity restricts its practical application. Herein, we design and synthesize novel hierarchical SiO 2 @C/TiO 2 (HSCT) hollow spheres via a template-directed method. These unique HSCT hollow spheres combine advantages from both TiO 2 such as cycle stability and SiO 2 with a high accessible area and ionic transport. In particular, the existence of a C layer is able to enhance the electrical conductivity. The SiO 2 layer with a porous structure can increase the ion diffusion channels and accelerate the ion transfer from the outer to the inner layers. The electrochemical measurements demonstrate that the HSCT-hollow-sphere-based electrode manifests a high specific capacitance of 1018 F g -1 at 1 A g -1 which is higher than those for hollow TiO 2 (113 F g -1 ) and SiO 2 /TiO 2 (252 F g -1 ) electrodes, and substantially higher than those of all the previously reported TiO 2 -based electrodes.

  17. Improvement of catalytic activity in selective oxidation of styrene with H{sub 2}O{sub 2} over spinel Mg–Cu ferrite hollow spheres in water

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Jinhui, E-mail: jinhuitong@126.com [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, Lanzhou 730070 (China); Key Laboratory of Gansu Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Cai, Xiaodong; Wang, Haiyan; Zhang, Qianping [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, Lanzhou 730070 (China); Key Laboratory of Gansu Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2014-07-01

    Graphical abstract: Uniform spinel Mg–Cu ferrite hollow spheres were prepared using carbon spheres as templates. Solid spinel Mg{sub 0.5}Cu{sub 0.5}Fe{sub 2}O{sub 4} ferrite nanocrystals were also prepared by sol–gel auto-combustion, hydrothermal and coprecipitation methods for comparison. The samples were found to be efficient catalysts for oxidation of styrene using hydrogen peroxide as oxidant. Especially, in the case of Mg{sub 0.5}Cu{sub 0.5}Fe{sub 2}O{sub 4} hollow spheres, obvious improvement on catalytic activity was observed and 21.2% of styrene conversion and 75.2% of selectivity for benzaldehyde were obtained at 80 °C for 6 h reaction in water. The catalyst can be magnetically separated easily for reuse and no obvious loss of activity was observed when reused in six consecutive runs. - Highlights: • Uniform spinel ferrite hollow spheres were prepared by a simple method. • The catalyst has been proved much more efficient for styrene oxidation than the reported analogues. • The catalyst can be easily separated by external magnetic field and has exhibited excellent reusability. • The catalytic system is environmentally friendly. - Abstract: Uniform spinel Mg–Cu ferrite hollow spheres were prepared using carbon spheres as templates. For comparison, solid Mg–Cu ferrite nanocrystals were also prepared by sol–gel auto-combustion, hydrothermal and coprecipitation methods. All the samples were characterized by Fourier transform infrared spectrophotometry (FT-IR), X-ray diffractometry (XRD), transmission electron microscopy (TEM) and N{sub 2} physisorption. The samples were found to be efficient catalysts for oxidation of styrene using hydrogen peroxide as oxidant. Especially, in the case of Mg{sub 0.5}Cu{sub 0.5}Fe{sub 2}O{sub 4} hollow spheres, obvious improvement on catalytic activity was observed, and 21.2% of styrene conversion and 75.2% of selectivity for benzaldehyde were obtained at 80 °C for 6 h reaction in water. The catalyst can be

  18. Remarkable activity of nitrogen-doped hollow carbon spheres encapsulated Cu on synthesis of dimethyl carbonate: Role of effective nitrogen

    Science.gov (United States)

    Li, Haixia; Zhao, Jinxian; Shi, Ruina; Hao, Panpan; Liu, Shusen; Li, Zhong; Ren, Jun

    2018-04-01

    A critical aspect in the improvement of the catalytic performance of Cu-based catalysts for the synthesis of dimethyl carbonate (DMC) is the development of an appropriate support. In this work, nitrogen-doped hollow carbon spheres (NHCSs), with 240 nm average diameter, 17 nm shell thickness, uniform mesoporous structure and a specific surface area of 611 m2 g-1, were prepared via a two-step Stӧber method. By varying the quantity of nitrogen-containing phenols used in the preparation it has been possible to control the nitrogen content and, consequently, the sphericity of the NHCSs. It was found that perfect spheres were obtained for nitrogen contents below 5.4 wt.%. The catalysts (Cu@NHCSs) were prepared by the hydrothermal impregnation method. The catalytic activity towards DMC synthesis was notably enhanced due to the immobilization effect on Cu particles and the enhanced electron transfer effect exercised by the effective nitrogen species, including pyridinic-N and graphitic-N. When the average size of the copper nanoparticles was 7.4 nm and the nitrogen content was 4.0 wt.%, the values of space-time yield of DMC and of turnover frequency (TOF) reached 1528 mg/(g h) and 11.0 h-1, respectively. The TOF value of Cu@NHCSs was 6 times higher than non-doped Cu@Carbon (2.1 h-1). The present work introduces the potential application of nitrogen-doped carbon materials and presents a novel procedure for the preparation of catalysts for DMC synthesis.

  19. Synthesis and characterization of hollow {alpha}-Fe{sub 2}O{sub 3} sub-micron spheres prepared by sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Lizbet, E-mail: lizbetlf@gmail.com; Bustamante, Angel; Osorio, Ana; Olarte, G. S. [Universidad Nacional Mayor de San Marcos (Peru); Santos Valladares, Luis De Los, E-mail: ld301@cam.ac.uk; Barnes, Crispin H. W. [University of Cambridge, Cavendish Laboratory (United Kingdom); Majima, Yutaka [Tokyo Institute of Technology, Materials and Structures Laboratory (Japan)

    2011-11-15

    In this work we report the preparation of magnetic hematite hollow sub-micron spheres ({alpha}-Fe{sub 2}O{sub 3}) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O) particles in citric acid solution by following the sol-gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180 Degree-Sign C resulted in an amorphous phase, without iron oxide formation. Annealing at 250 Degree-Sign C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400 Degree-Sign C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600 Degree-Sign C. The characterization was performed by X-ray diffraction (XRD), Moessbauer spectroscopy (MS) and scanning electron microscopy (SEM).

  20. Eosin Y-sensitized nanosheet-stacked hollow-sphere TiO2 for efficient photocatalytic H2 production under visible-light irradiation

    Science.gov (United States)

    Shi, Jinwen; Guan, Xiangjiu; Zhou, Zhaohui; Liu, Haipei; Guo, Liejin

    2015-06-01

    Nanosheet (with around 20 nm in thickness)-stacked hollow-sphere TiO2 was synthesized via a modified solvothermal reaction for different times followed by calcination treatment at different temperatures. After surface modification by different cations (H+ or Fe3+) and further sensitization by Eosin Y, the obtained photocatalysts achieved remarkably enhanced H2-production activity (about 4.2 times of that for Eosin Y-sensitized P25) and stability under visible-light irradiation. The improved photocatalytic performance was synergistically caused by the enhanced Eosin Y sensitization (due to the enlarged surface area and electropositively modified surface), the optimized crystal structure (well-crystallized anatase phase), and the unique micro/nanostructure (nanosheet-stacked hollow spheres). This work presented an effective route to explore new visible-light-driven H2-production photocatalysts by coupling nanomaterials with special morphologies and metal-free dyes with visible-light absorption.

  1. Eosin Y-sensitized nanosheet-stacked hollow-sphere TiO2 for efficient photocatalytic H2 production under visible-light irradiation

    International Nuclear Information System (INIS)

    Shi, Jinwen; Guan, Xiangjiu; Zhou, Zhaohui; Liu, Haipei; Guo, Liejin

    2015-01-01

    Nanosheet (with around 20 nm in thickness)-stacked hollow-sphere TiO 2 was synthesized via a modified solvothermal reaction for different times followed by calcination treatment at different temperatures. After surface modification by different cations (H + or Fe 3+ ) and further sensitization by Eosin Y, the obtained photocatalysts achieved remarkably enhanced H 2 -production activity (about 4.2 times of that for Eosin Y-sensitized P25) and stability under visible-light irradiation. The improved photocatalytic performance was synergistically caused by the enhanced Eosin Y sensitization (due to the enlarged surface area and electropositively modified surface), the optimized crystal structure (well-crystallized anatase phase), and the unique micro/nanostructure (nanosheet-stacked hollow spheres). This work presented an effective route to explore new visible-light-driven H 2 -production photocatalysts by coupling nanomaterials with special morphologies and metal-free dyes with visible-light absorption

  2. A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO 2 adsorption

    KAUST Repository

    Wang, Yu

    2015-01-01

    © The Royal Society of Chemistry 2015. Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m2 g-1 were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.42 mmol g-1).

  3. Experimental Study on Variable-Amplitude Fatigue of Welded Cross Plate-Hollow Sphere Joints in Grid Structures

    Directory of Open Access Journals (Sweden)

    Jin-Feng Jiao

    2018-01-01

    Full Text Available The fatigue stress amplitude of the welded cross plate-hollow sphere joint (WCPHSJ in a grid structure varies due to the random loading produced by suspending cranes. A total of 14 specimens considering three different types of WCPHSJs were prepared and tested using a specially designed test rig. Four typical loading conditions, “low-high,” “high-low,” “low-high-low,” and “high-low-high,” were first considered in the tests to investigate the fatigue behavior under variable load amplitudes, followed by metallographic analyses. The experimental and metallographic analysis results provide a fundamental understanding on the fatigue fracture form and fatigue mechanism of WCPHSJs. Based on the available data from constant-amplitude fatigue tests, the variable-amplitude fatigue life of the three types of WCPHSJs was estimated using the Miner rule and Corten-Dolan theory. Since both accumulative damage theories yield virtually same damaging results, the Miner rule is hence suggested to estimate the fatigue life of WCPHSJs.

  4. Size- and shape-controlled synthesis of hexagonal bipyramidal crystals and hollow self-assembled Al-MOF spheres

    KAUST Repository

    Sarawade, Pradip; Tan, Hua; Anjum, Dalaver H.; Cha, Dong Kyu; Polshettiwar, Vivek

    2013-01-01

    We report an efficient protocol for the synthesis of monodisperse crystals of an aluminum (Al)-based metal organic framework (MOF) while obtaining excellent control over the size and shape solely by tuning of the reaction parameters without the use of a template or structure-directing agent. The size of the hexagonal crystals of the Al-MOF can be selectively varied from 100 nm to 2000 nm by simply changing the reaction time and temperature via its nucleation-growth mechanism. We also report a self-assembly phenomenon, observed for the first time in case of Al-MOF, whereby hollow spheres of Al-MOF were formed by the spontaneous organization of triangular sheet building blocks. These MOFs showed broad hysteresis loops during the CO2 capture, indicating that the adsorbed CO2 is not immediately desorbed upon decreasing the external pressure and is instead confined within the framework, which allows for the capture and subsequent selective trapping of CO2 from gaseous mixtures. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Hollow mesoporous carbon spheres-based fiber coating for solid-phase microextraction of polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Hu, Xingru; Liu, Chao; Li, Jiansheng; Luo, Rui; Jiang, Hui; Sun, Xiuyun; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

    2017-10-20

    In this study, a novel hollow mesoporous carbon spheres-based fiber (HMCSs-F) was fabricated to immobilize HMCSs onto a stainless steel wire for solid-phase microextraction (SPME). Characterization results showed that the HMCSs-F possessed a large specific surface area, high porosity and uniform pore size. To demonstrate the extraction performance, a series of polycyclic aromatic hydrocarbons (PAHs) was chosen as target analytes. The experimental parameters including extraction and desorption conditions were optimized. Compared to commercial fibers, the HMCSs-F exhibited better extraction efficiency for PAHs. More interestingly, a good extraction selectivity for PAHs from the complex matrix was observed in these HMCSs-F. The enhanced SPME performance was attributed to the unique pore structure and special surface properties of the HMCSs. Furthermore, under the optimum conditions, the limits of detection (LODs) for the HMCSs-F were in the range of 0.20-1.15ngL -1 with a corresponding relative standard deviation that was below 8.6%. The method was successfully applied for the analysis of PAHs in actual environmental water samples with recoveries ranging from 85.9% to 112.2%. These results imply that the novel HMCSs-F have potential application in environmental water analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Size- and shape-controlled synthesis of hexagonal bipyramidal crystals and hollow self-assembled Al-MOF spheres

    KAUST Repository

    Sarawade, Pradip

    2013-11-25

    We report an efficient protocol for the synthesis of monodisperse crystals of an aluminum (Al)-based metal organic framework (MOF) while obtaining excellent control over the size and shape solely by tuning of the reaction parameters without the use of a template or structure-directing agent. The size of the hexagonal crystals of the Al-MOF can be selectively varied from 100 nm to 2000 nm by simply changing the reaction time and temperature via its nucleation-growth mechanism. We also report a self-assembly phenomenon, observed for the first time in case of Al-MOF, whereby hollow spheres of Al-MOF were formed by the spontaneous organization of triangular sheet building blocks. These MOFs showed broad hysteresis loops during the CO2 capture, indicating that the adsorbed CO2 is not immediately desorbed upon decreasing the external pressure and is instead confined within the framework, which allows for the capture and subsequent selective trapping of CO2 from gaseous mixtures. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. A Sortase A-Immobilized Mesoporous Hollow Carbon Sphere-Based Biosensor for Detection of Gram-Positive Bacteria

    Science.gov (United States)

    Wang, Hongsu; Luo, Ruiping; Chen, Yang; Si, Qi; Niu, Xiaodi

    2018-05-01

    A sensor based on mesoporous carbon materials immobilized with sortase A (SrtA) for determination of Staphylococcus aureus (S. aureus) is reported. To prepare the biosensor, we first synthesized carboxyl-functionalized mesoporous hollow carbon spheres, then applied them as carriers for immobilization of SrtA. Based on the catalytic mechanism of SrtA, a highly sensitive, inexpensive, and rapid method was developed for S. aureus detection. The sensor showed a linear response in the bacterial concentration range of 0.125 × 102 colony-forming units (CFU) mL-1 to 2.5 × 102 CFU mL-1, with detection limit as low as 9.0 CFU mL-1. The method was successfully used for quantitative detection of S. aureus in whole milk samples, giving results similar to experimental results obtained from the plate counting method. This biosensor could also be used to detect other Gram-positive bacteria that secrete SrtA.

  8. A novel enzymatic glucose sensor based on Pt nanoparticles-decorated hollow carbon spheres-modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Luhana, Charles; Bo Xiangjie; Ju Jian; Guo Liping

    2012-01-01

    A new glucose biosensor was developed based on hollow carbon spheres decorated with platinum nanoparticles (Pt/HCSs)-modified glassy carbon electrode immobilized with glucose oxidase (GOx) with the help of Nafion. The Pt nanoparticles were well dispersed on the HCSs with an average size of 2.29 nm. The detection of glucose was achieved via electrochemical detection of the enzymatically liberated H 2 O 2 at +0.5 V versus Ag/AgCl at physiologic pH of 7.4. The Pt/HCSs-modified electrode exhibited excellent electrocatalytic activities toward both the oxidation and reduction of H 2 O 2 . The glucose biosensor showed good electrocatalytic performance in terms of high sensitivity (4.1 μA mM −1 ), low detection limit (1.8 μM), fast response time m ) and the maximum current density (i max ) values for the biosensor were 10.94 mM and 887 μA cm −2 respectively. Furthermore, this biosensor showed an acceptable reproducibility and high stability. The interfering signals from ascorbic acid and uric acid at concentration levels normally found in human blood were not much compared with the response to glucose. Blood serum samples were also tested with this biosensor and a good recovery was achieved for the two spiked serum samples.

  9. Nitrogen-Doped Hollow Carbon Spheres with Embedded Co Nanoparticles as Active Non-Noble-Metal Electrocatalysts for the Oxygen Reduction Reaction

    Directory of Open Access Journals (Sweden)

    Ruohao Xing

    2018-02-01

    Full Text Available Transition metal (Fe, Co, Ni complexes on carbon nanomaterials are promising candidates as electrocatalysts towards the oxygen reduction reaction (ORR. In this paper, nitrogen-doped hollow carbon spheres with embedded Co nanoparticles were successfully prepared via a controllable synthesis strategy. The morphology characterization shows that the hollow carbon spheres possess an average diameter of ~150 nm with a narrow size distribution and a shell thickness of ~14.5 nm. The content of N doping ranges from 2.1 to 6.6 at.% depending on the calcination temperature from 900 to 1050 °C. Compared with commercial Pt/C, the Co-containing nitrogen-doped hollow carbon spheres prepared at 900 °C (CoNHCS-900 as an ORR electrocatalyst shows a half-wave potential shift of only ∆E1/2 = 55 mV, but a superior stability of about 90.2% maintenance after 20,000 s in the O2-saturated 0.1 M KOH at a rotating speed of 1600 rpm. This could be ascribed to the synergistic effects of N-containing moieties, Co-Nx species, and Co nanoparticles, which significantly increase the density of active sites and promote the charge transfer during the ORR process.

  10. Biomolecule-assisted synthesis of defect-mediated Cd1-xZnxS/MoS2/graphene hollow spheres for highly efficient hydrogen evolution.

    Science.gov (United States)

    Du, Ruifeng; Zhang, Yihe; Li, Baoying; Yu, Xuelian; Liu, Huijuan; An, Xiaoqiang; Qu, Jiuhui

    2016-06-28

    Moderate efficiency and the utilization of noble metal cocatalysts are the key factors that restrict the large-scale application of photocatalytic hydrogen production. To develop more efficient photocatalysts based on earth abundant elements, either a new material strategy or a fundamental understanding of the semiconductor/cocatalyst interfaces is highly desirable. In this paper, we studied the feasibility of in situ formation of defect-rich cocatalysts on graphene-based photocatalysts. A facile biomolecule-assisted strategy was used to self-assmble Cd1-xZnxS/MoS2/graphene hollow spheres. The defect-mediated cocatalyst and synergetic charge transfer around heterostructured interfaces exhibit a significant impact on the visible-light-driven photocatalytic activity of multicomponent solid solutions. With engineered interfacial defects, Cd0.8Zn0.2S/MoS2/graphene hollow spheres exhibited a 63-fold improved H2 production rate, which was even 2 and 3.8 times higher than those of CdS/MoS2/graphene hollow spheres and Cd0.8Zn0.2S/Pt. Therefore, our research provides a promising approach for the rational design of high-efficiency and low-cost photocatalysts for solar fuel production.

  11. Effect of Hollow Sphere Size and Distribution on the Quasi-Static and High Strain Rate Compressive Properties of Al-A380-Al2O3 Syntactic Foams

    Science.gov (United States)

    2012-01-01

    heat exchangers, flotation devices, energy absorbers and as decorative building materials. A class of foam material, where the voids are contained...hollow spheres are presented in Table 1 (information provided by suppliers). The hollow spheres were supplied by C-E Minerals in standard size...through TACOM R&D Contract# W56HZV-08-C-0716. The authors would also like to acknowledge and thank C-E Minerals for providing the ALODUR alumina

  12. Electromagnetic wave absorption properties of composites with ultrafine hollow magnetic fibers

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Jin Woo [Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (BK21 Granted Program), 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Composites Research Center, Korea Institute of Materials Science, 66 Sang-nam-dong, Changwon, Gyeongnam (Korea, Republic of); Lee, Sang Bok; Kim, Jin Bong; Lee, Sang Kwan [Composites Research Center, Korea Institute of Materials Science, 66 Sang-nam-dong, Changwon, Gyeongnam (Korea, Republic of); Park, O Ok, E-mail: oopark@kaist.ac.kr [Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (BK21 Granted Program), 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 50-1, Sang-ri, Hyeongpung-myeon, Dalseong-gun, Daegu 711-873 (Korea, Republic of)

    2014-06-01

    Ultrafine hollow magnetic fibers were prepared by electroless plating using hydrolyzed polyester fiber as a sacrificial substrate. These hollow fibers can be served for lightweight and efficient electromagnetic (EM) absorbing materials. As observed from SEM and EDS analysis, hollow structures consisting of Ni inner layer and Fe or Fe–Co outer layer were obtained. By introducing Co onto Fe, oxidation of the Fe layer was successfully prevented making it possible to enhance the complex permeability compared to a case in which only Fe was used. Polymeric composites containing the hollow fibers with different weight fractions and fiber lengths were prepared by a simple mixing process. The electromagnetic wave properties of the composites were measured by a vector network analyzer and it was found that the hollow magnetic fibers show a clear resonance peak of the complex permittivity around the X-band range (8–12 GHz) and the resonance frequency strongly depends on the fiber concentration and length. A possible explanation for the unique resonance is that the hollow fibers possess relatively low electrical conductivity and a long mean free path due to their oxidized phase and hollow structure. The calculated EM wave absorption with the measured EM wave properties showed that the composite containing 30 wt% hollow Ni/Fe–Co (7:3) fibers in length of 180 μm exhibited multiple absorbance peaks resulting in a broad absorption bandwidth of 4.2 GHz. It is obvious that this multiple absorbance is attributed to the resonance characteristic of the composite. - Highlights: • The ultrafine hollow fibers consist of inner Ni layer (∼100 nm) and outer Fe or Fe–Co layer (500–700 nm). • Composites with the fibers show a high permittivity as well as permeability at low weight fractions (10–30 wt%). • The composites show a permittivity resonance and the resonance frequency can be controlled by fiber content and length. • The composite absorber exhibits a double

  13. A sulfur host based on titanium monoxide@carbon hollow spheres for advanced lithium-sulfur batteries.

    Science.gov (United States)

    Li, Zhen; Zhang, Jintao; Guan, Buyuan; Wang, Da; Liu, Li-Min; Lou, Xiong Wen David

    2016-10-20

    Lithium-sulfur batteries show advantages for next-generation electrical energy storage due to their high energy density and cost effectiveness. Enhancing the conductivity of the sulfur cathode and moderating the dissolution of lithium polysulfides are two key factors for the success of lithium-sulfur batteries. Here we report a sulfur host that overcomes both obstacles at once. With inherent metallic conductivity and strong adsorption capability for lithium-polysulfides, titanium monoxide@carbon hollow nanospheres can not only generate sufficient electrical contact to the insulating sulfur for high capacity, but also effectively confine lithium-polysulfides for prolonged cycle life. Additionally, the designed composite cathode further maximizes the lithium-polysulfide restriction capability by using the polar shells to prevent their outward diffusion, which avoids the need for chemically bonding all lithium-polysulfides on the surfaces of polar particles.

  14. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  15. A novel enzymatic glucose sensor based on Pt nanoparticles-decorated hollow carbon spheres-modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Luhana, Charles; Bo Xiangjie; Ju Jian; Guo Liping, E-mail: guolp078@nenu.edu.cn [Northeast Normal University, Faculty of Chemistry (China)

    2012-10-15

    A new glucose biosensor was developed based on hollow carbon spheres decorated with platinum nanoparticles (Pt/HCSs)-modified glassy carbon electrode immobilized with glucose oxidase (GOx) with the help of Nafion. The Pt nanoparticles were well dispersed on the HCSs with an average size of 2.29 nm. The detection of glucose was achieved via electrochemical detection of the enzymatically liberated H{sub 2}O{sub 2} at +0.5 V versus Ag/AgCl at physiologic pH of 7.4. The Pt/HCSs-modified electrode exhibited excellent electrocatalytic activities toward both the oxidation and reduction of H{sub 2}O{sub 2}. The glucose biosensor showed good electrocatalytic performance in terms of high sensitivity (4.1 {mu}A mM{sup -1}), low detection limit (1.8 {mu}M), fast response time <3 s, and wide linear range (0.04-8.62 mM). The apparent Michaelis-Menten constant (K{sub m}) and the maximum current density (i{sub max}) values for the biosensor were 10.94 mM and 887 {mu}A cm{sup -2} respectively. Furthermore, this biosensor showed an acceptable reproducibility and high stability. The interfering signals from ascorbic acid and uric acid at concentration levels normally found in human blood were not much compared with the response to glucose. Blood serum samples were also tested with this biosensor and a good recovery was achieved for the two spiked serum samples.

  16. Solvothermal synthesis of monodisperse LiFePO4 micro hollow spheres as high performance cathode material for lithium ion batteries.

    Science.gov (United States)

    Yang, Shiliu; Hu, Mingjun; Xi, Liujiang; Ma, Ruguang; Dong, Yucheng; Chung, C Y

    2013-09-25

    A microspherical, hollow LiFePO4 (LFP) cathode material with polycrystal structure was simply synthesized by a solvothermal method using spherical Li3PO4 as the self-sacrificed template and FeCl2·4H2O as the Fe(2+) source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the LFP micro hollow spheres have a quite uniform size of ~1 μm consisting of aggregated nanoparticles. The influences of solvent and Fe(2+) source on the phase and morphology of the final product were chiefly investigated, and a direct ion exchange reaction between spherical Li3PO4 templates and Fe(2+) ions was firstly proposed on the basis of the X-ray powder diffraction (XRD) transformation of the products. The LFP nanoparticles in the micro hollow spheres could finely coat a uniform carbon layer ~3.5 nm by a glucose solution impregnating-drying-sintering process. The electrochemical measurements show that the carbon coated LFP materials could exhibit high charge-discharge capacities of 158, 144, 125, 101, and even 72 mAh g(-1) at 0.1, 1, 5, 20, and 50 C, respectively. It could also maintain 80% of the initial discharge capacity after cycling for 2000 times at 20 C.

  17. Facile Synthesis of V2O5 Hollow Spheres as Advanced Cathodes for High-Performance Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Xingyuan Zhang

    2017-01-01

    Full Text Available Three-dimensional V2O5 hollow structures have been prepared through a simple synthesis strategy combining solvothermal treatment and a subsequent thermal annealing. The V2O5 materials are composed of microspheres 2–3 μm in diameter and with a distinct hollow interior. The as-synthesized V2O5 hollow microspheres, when evaluated as a cathode material for lithium-ion batteries, can deliver a specific capacity as high as 273 mAh·g−1 at 0.2 C. Benefiting from the hollow structures that afford fast electrolyte transport and volume accommodation, the V2O5 cathode also exhibits a superior rate capability and excellent cycling stability. The good Li-ion storage performance demonstrates the great potential of this unique V2O5 hollow material as a high-performance cathode for lithium-ion batteries.

  18. Combined use of lightweight magnetic Fe{sub 3}O{sub 4}-coated hollow glass spheres and electrically conductive reduced graphene oxide in an epoxy matrix for microwave absorption

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junpeng; Wang, Jun, E-mail: wgdfrp@whut.edu.cn; Zhang, Bin; Sun, Yu; Chen, Wei; Wang, Tao

    2016-03-01

    Epoxy resin based lightweight composites comprising Fe{sub 3}O{sub 4}-coated hollow glass spheres (HGS@Fe{sub 3}O{sub 4}) and reduced graphene oxide (RGO) were prepared. Impedance matching condition and electromagnetic wave attenuation characteristic are used for analysis of the reflection loss (RL) performance of the composites. Compared with pure HGS@Fe{sub 3}O{sub 4} and RGO composite, the −10 dB absorption bandwidth and the minimum RL of the hybrid composites are enhanced. RL values less than −10 dB are obtained in a wide frequency range and the corresponding bandwidth can reach up to 3.6 GHz when an appropriate absorber thickness is chosen. The density of the hybrid composite is in the range of 0.57–0.72 g/cm{sup 3}, which is attractive candidate for a new type of lightweight microwave absorber. - Highlights: • Lightweight composites comprising HGS@Fe{sub 3}O{sub 4} and RGO were prepared. • The RL less than −10 dB can reach up to 3.6 GHz with layer thickness of 2.5 mm. • The density of the composites is in the range of 0.57−0.72 g/cm{sup 3}.

  19. Eosin Y-sensitized nanosheet-stacked hollow-sphere TiO{sub 2} for efficient photocatalytic H{sub 2} production under visible-light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Jinwen, E-mail: jinwen-shi@mail.xjtu.edu.cn; Guan, Xiangjiu; Zhou, Zhaohui; Liu, Haipei; Guo, Liejin [Xi’an Jiaotong University (XJTU), State Key Laboratory of Multiphase Flow in Power Engineering (MFPE), International Research Center for Renewable Energy IRCRE (China)

    2015-06-15

    Nanosheet (with around 20 nm in thickness)-stacked hollow-sphere TiO{sub 2} was synthesized via a modified solvothermal reaction for different times followed by calcination treatment at different temperatures. After surface modification by different cations (H{sup +} or Fe{sup 3+}) and further sensitization by Eosin Y, the obtained photocatalysts achieved remarkably enhanced H{sub 2}-production activity (about 4.2 times of that for Eosin Y-sensitized P25) and stability under visible-light irradiation. The improved photocatalytic performance was synergistically caused by the enhanced Eosin Y sensitization (due to the enlarged surface area and electropositively modified surface), the optimized crystal structure (well-crystallized anatase phase), and the unique micro/nanostructure (nanosheet-stacked hollow spheres). This work presented an effective route to explore new visible-light-driven H{sub 2}-production photocatalysts by coupling nanomaterials with special morphologies and metal-free dyes with visible-light absorption.

  20. Construct 3D porous hollow Co3O4 micro-sphere: A potential oxidizer of nano-energetic materials with superior reactivity

    Science.gov (United States)

    Wang, Jun; Zheng, Bo; Qiao, Zhiqiang; Chen, Jin; Zhang, Liyuan; Zhang, Long; Li, Zhaoqian; Zhang, Xingquan; Yang, Guangcheng

    2018-06-01

    High energy density and rapid reactivity are the future trend for nano-energetic materials. Energetic performance of nano-energetic materials depends on the interfacial diffusion and mass transfer during the reacted process. However, the development of desired structure to significantly enhance reactivity still remains challenging. Here we focused on the design and preparation of 3D porous hollow Co3O4 micro-spheres, in which gas-blowing agents (air) and maximize interfacial interactions were introduced to enhance mass transport and reduce the diffusion distance between the oxidizer and fuel (Aluminum). The 3D hierarchical Co3O4/Al based nano-energetic materials show a low-onset decomposition temperature (423 °C), and high heat output (3118 J g-1) resulting from porous and hollow nano-structure of Co3O4 micro-spheres. Furthermore, 3D hierarchical Co3O4/Al arrays were directly fabricated on the silicon substrate, which was fully compatible with silicon-based microelectromechanical systems to achieve functional nanoenergetics-on-a-chip. This approach provides a simple and efficient way to fabricate 3D ordered nano-energetic arrays with superior reactivity and the potential on the application in micro-energetic devices.

  1. Classical molecular dynamics and quantum ab-initio studies on lithium-intercalation in interconnected hollow spherical nano-spheres of amorphous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, A. [Atomic Scale Modelling and Materials, Department of Energy Conversion and Storage, Technical University of Denmark, Rios Campus, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Malik, R. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302 (India); Prakash, S. [Defense Metallurgical Research Laboratory, Hyderabad (India); Sarkar, T.; Bharadwaj, M.D. [Center for Study of Science Technology and Policy, Bangalore 560094 (India); Aich, S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302 (India); Ghosh, S., E-mail: sudipto@metal.iitkgp.ernet.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302 (India)

    2016-04-25

    A high concentration of lithium, corresponding to charge capacity of ∼4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles. The present work argues that the hollow spherical geometry alone cannot ensure the absence of fracture. Using classical molecular dynamics and density functional theory based simulations; satisfactory explanation to the absence of fracture has been explored at the atomic scale. - Highlights: • Interconnected nanoshells of amorphous Si: best available lithium ion cell anode. • High cycle life not understood in the light of poor K{sub IC} of amorphous Si. • MD reveals: atomic density of interconnected structure is ∼16% less than bulk Si. • Leads to drastic reduction (DFT) in lithiation σ & metal like e{sup −} structure (high K{sub IC}). • Lowering of lithiation σ and increase in K{sub IC} result in high cycle life.

  2. Classical molecular dynamics and quantum abs-initio studies on lithium-intercalation in interconnected hollow spherical nano-spheres of amorphous Silicon

    DEFF Research Database (Denmark)

    Bhowmik, Arghya; Malik, R.; Prakash, S.

    2016-01-01

    A high concentration of lithium, corresponding to charge capacity of ~4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnec......A high concentration of lithium, corresponding to charge capacity of ~4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently...... interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles. The present work argues...... that the hollow spherical geometry alone cannot ensure the absence of fracture. Using classical molecular dynamics and density functional theory based simulations; satisfactory explanation to the absence of fracture has been explored at the atomic scale....

  3. Sandwich-like C@SnO2/Sn/void@C hollow spheres as improved anode materials for lithium ion batteries

    Science.gov (United States)

    Wang, Huijun; Jiang, Xinya; Chai, Yaqin; Yang, Xia; Yuan, Ruo

    2018-03-01

    As lithium ion batteries (LIBs) anode, SnO2 suffers fast capacity fading due to its large volume expansion during discharge/charge process. To overcome the problem, sandwich-like C@SnO2/Sn/void@C hollow spheres (referred as C@SnO2/Sn/void@C HSs) are prepared by in-situ polymerization and carbonization, using hollow SnO2 as self-template and dopamine as carbon source. The C@SnO2/Sn/void@C HSs possesses the merits of hollow and core/void/shell structure, so that they can accommodate the volume change under discharge/charge process, shorten the transmission distance of Li ions, own more contact area for the electrolyte. Thanks to these advantages, C@SnO2/Sn/void@C HSs display excellent electrochemical performance as anode materials for LIBs, which deliver a high capacity of 786.7 mAh g-1 at the current density of 0.5 A g-1 after 60 cycles. The simple synthesis method for C@SnO2/Sn/void@C HSs with special structure will provide a promising method for preparing other anode materials for LIBs.

  4. Electro-magnetic properties of composites with aligned Fe-Co hollow fibers

    Directory of Open Access Journals (Sweden)

    Seungchan Cho

    2016-05-01

    Full Text Available A novel Fe-Co binary hollow fiber was synthesized by electroless plating using hydrolyzed polyester fiber and its anisotropy characteristic was investigated for electromagnetic wave absorbing materials. The hollow fibers in parallel with magnetic field show higher saturated magnetization of 202 emu/g at the applied magnetic field of 10 kOe and lower coercivity (27.658 Oe, compared with the random and vertical oriented hollow fibers. From complex permittivity measurement, the Fe-Co hollow fiber composites clearly display a single dielectric resonance, located at ∼14 GHz. The Fe-Co hollow fibers not only provide excellent EM properties in GHz frequency ranges, resulting mainly from the strong resonance, but also adjust the soft magnetic properties through fiber alignments. The cavitary structure of the Fe-Co hollow fibers, not only giving rise to a dielectric loss resonance and also adjusting its peak frequency, may be a pathway to useful EM wave absorptive devices in GHz frequency ranges.

  5. Thermal Diffusivity and Thermal Conductivity of Dispersed Glass Sphere Composites Over a Range of Volume Fractions

    Science.gov (United States)

    Carson, James K.

    2018-06-01

    Glass spheres are often used as filler materials for composites. Comparatively few articles in the literature have been devoted to the measurement or modelling of thermal properties of composites containing glass spheres, and there does not appear to be any reported data on the measurement of thermal diffusivities over a range of filler volume fractions. In this study, the thermal diffusivities of guar-gel/glass sphere composites were measured using a transient comparative method. The addition of the glass beads to the gel increased the thermal diffusivity of the composite, more than doubling the thermal diffusivity of the composite relative to the diffusivity of the gel at the maximum glass volume fraction of approximately 0.57. Thermal conductivities of the composites were derived from the thermal diffusivity measurements, measured densities and estimated specific heat capacities of the composites. Two approaches to modelling the effective thermal diffusivity were considered.

  6. Simple Synthesis of Molybdenum Disulfide/Reduced Graphene Oxide Composite Hollow Microspheres as Supercapacitor Electrode Material.

    Science.gov (United States)

    Xiao, Wei; Zhou, Wenjie; Feng, Tong; Zhang, Yanhua; Liu, Hongdong; Tian, Liangliang

    2016-09-20

    MoS₂/RGO composite hollow microspheres were hydrothermally synthesized by using SiO₂/GO microspheres as a template, which were obtained via the sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO₂ microspheres. The structure, morphology, phase, and chemical composition of MoS₂/RGO hollow microspheres were systematically investigated by a series of techniques such as FE-SEM, TEM, XRD, TGA, BET, and Raman characterizations, meanwhile, their electrochemical properties were carefully evaluated by CV, GCD, and EIS measurements. It was found that MoS₂/RGO hollow microspheres possessed unique porous hollow architecture with high-level hierarchy and large specific surface area up to 63.7 m²·g -1 . When used as supercapacitor electrode material, MoS₂/RGO hollow microspheres delivered a maximum specific capacitance of 218.1 F·g -1 at the current density of 1 A·g -1 , which was much higher than that of contrastive bare MoS₂ microspheres developed in the present work and most of other reported MoS₂-based materials. The enhancement of supercapacitive behaviors of MoS₂/RGO hollow microspheres was likely due to the improved conductivity together with their distinct structure and morphology, which not only promoted the charge transport but also facilitated the electrolyte diffusion. Moreover, MoS₂/RGO hollow microsphere electrode displayed satisfactory long-term stability with 91.8% retention of the initial capacitance after 1000 charge/discharge cycles at the current density of 3 A·g -1 , showing excellent application potential.

  7. Simple Synthesis of Molybdenum Disulfide/Reduced Graphene Oxide Composite Hollow Microspheres as Supercapacitor Electrode Material

    Directory of Open Access Journals (Sweden)

    Wei Xiao

    2016-09-01

    Full Text Available MoS2/RGO composite hollow microspheres were hydrothermally synthesized by using SiO2/GO microspheres as a template, which were obtained via the sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO2 microspheres. The structure, morphology, phase, and chemical composition of MoS2/RGO hollow microspheres were systematically investigated by a series of techniques such as FE-SEM, TEM, XRD, TGA, BET, and Raman characterizations, meanwhile, their electrochemical properties were carefully evaluated by CV, GCD, and EIS measurements. It was found that MoS2/RGO hollow microspheres possessed unique porous hollow architecture with high-level hierarchy and large specific surface area up to 63.7 m2·g−1. When used as supercapacitor electrode material, MoS2/RGO hollow microspheres delivered a maximum specific capacitance of 218.1 F·g−1 at the current density of 1 A·g−1, which was much higher than that of contrastive bare MoS2 microspheres developed in the present work and most of other reported MoS2-based materials. The enhancement of supercapacitive behaviors of MoS2/RGO hollow microspheres was likely due to the improved conductivity together with their distinct structure and morphology, which not only promoted the charge transport but also facilitated the electrolyte diffusion. Moreover, MoS2/RGO hollow microsphere electrode displayed satisfactory long-term stability with 91.8% retention of the initial capacitance after 1000 charge/discharge cycles at the current density of 3 A·g−1, showing excellent application potential.

  8. A template-free solvothermal synthesis and photoluminescence properties of multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres

    Science.gov (United States)

    Sang, Xiaotong; Xu, Guangxi; Lian, Jingbao; Wu, Nianchu; Zhang, Xue; He, Jiao

    2018-06-01

    The multicolor Gd2O2S:xTb3+, yEu3+ hollow spheres were successfully synthesized via a template-free solvothermal route without the use of surfactant from commercially available Ln (NO3)3·6H2O (Ln = Gd, Tb and Eu), absolute ethanol, ethanediamine and sublimed sulfur as the starting materials. The phase, structure, particle morphology and photoluminescence (PL) properties of the as-obtained products were investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and photoluminescence spectra. The influence of synthetic time on phase, structure and morphology was systematically investigated and discussed. The possible formation mechanism depending on synthetic time t for the Gd2O2S phase has been presented. These results demonstrate that the Gd2O2S hollow spheres could be obtained under optimal condition, namely solvothermal temperature T = 220 °C and synthetic time t = 16 h. The as-obtained Gd2O2S sample possesses hollow sphere structure, which has a typical size of about 2.5 μm in diameter and about 0.5 μm in shell thickness. PL spectroscopy reveals that the strongest emission peak for the Gd2O2S:xTb3+ and the Gd2O2S:yEu3+ samples is located at 545 nm and 628 nm, corresponding to 5D4→7F5 transitions of Tb3+ ions and 5D0→7F2 transitions of Eu3+ ions, respectively. The quenching concentration of Tb3+ ions and Eu3+ ions is 7%. In the case of Tb3+ and Eu3+ co-doped samples, when the concentration of Tb3+ or Eu3+ ions is 7%, the optimum concentration of Eu3+ or Tb3+ ions is determined to be 1%. Under 254 nm ultraviolet (UV) light excitation, the Gd2O2S:7%Tb3+, the Gd2O2S:7%Tb3+,1%Eu3+ and the Gd2O2S:7%Eu3+ samples give green, yellow and red light emissions, respectively. And the corresponding CIE coordinates vary from (0.3513, 0.5615), (0.4120, 0.4588) to (0.5868, 0.3023), which is also well consistent with their luminous photographs.

  9. Current—voltage characteristics of lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composites

    International Nuclear Information System (INIS)

    De-An, Pan; Shen-Gen, Zhang; Jian-Jun, Tian; Li-Jie, Qiao; Jun-Sai, Sun; Volinsky, Alex A.

    2010-01-01

    Current–voltage measurements obtained from lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composite showed that a sinusoidal current applied to the copper coil wrapped around the hollow cylinder circumference induces voltage across the lead zirconate titanate layer thickness. The current–voltage coefficient and the maximum induced voltage in lead zirconate titanate at 1 kHz and resonance (60.1 kHz) frequencies increased linearly with the number of the coil turns and the applied current. The resonance frequency corresponds to the electromechanical resonance frequency. The current–voltage coefficient can be significantly improved by optimizing the magnetoelectric structure geometry and/or increasing the number of coil turns. Hollow cylindrical lead zirconate titanate/nickel structures can be potentially used as current sensors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  10. Multifunctional Roles of TiO 2 Nanoparticles for Architecture of Complex Core−Shells and Hollow Spheres of SiO 2 −TiO 2 −Polyaniline System

    KAUST Repository

    Wang, Dan Ping; Zeng, Hua Chun

    2009-01-01

    to prepare inorganic-polymer nanocomposites. In this work, we explore the roles of metal-oxide nanoparticles (anatase TiO2) in the area of constructional synthesis of highly complex core-shell and hollow sphere nanostructures comprising SiO2, TiO2

  11. Real-Time Fluorescence Detection in Aqueous Systems by Combined and Enhanced Photonic and Surface Effects in Patterned Hollow Sphere Colloidal Photonic Crystals.

    Science.gov (United States)

    Zhong, Kuo; Wang, Ling; Li, Jiaqi; Van Cleuvenbergen, Stijn; Bartic, Carmen; Song, Kai; Clays, Koen

    2017-05-16

    Hollow sphere colloidal photonic crystals (HSCPCs) exhibit the ability to maintain a high refractive index contrast after infiltration of water, leading to extremely high-quality photonic band gap effects, even in an aqueous (physiological) environment. Superhydrophilic pinning centers in a superhydrophobic environment can be used to strongly confine and concentrate water-soluble analytes. We report a strategy to realize real-time ultrasensitive fluorescence detection in patterned HSCPCs based on strongly enhanced fluorescence due to the photonic band-edge effect combined with wettability differentiation in the superhydrophobic/superhydrophilic pattern. The orthogonal nature of the two strategies allows for a multiplicative effect, resulting in an increase of two orders of magnitude in fluorescence.

  12. Ultrathin-shell boron nitride hollow spheres as sorbent for dispersive solid-phase extraction of polychlorinated biphenyls from environmental water samples.

    Science.gov (United States)

    Fu, Meizhen; Xing, Hanzhu; Chen, Xiangfeng; Chen, Fan; Wu, Chi-Man Lawrence; Zhao, Rusong; Cheng, Chuange

    2014-11-21

    Boron nitride hollow spheres with ultrathin-shells were synthesized and used as sorbents for dispersive solid-phase extraction of aromatic pollutants at trace levels from environmental water samples. Polychlorinated biphenyls (PCBs) were selected as target compounds. Sample quantification and detection were performed by gas chromatography-tandem mass spectrometry. Extraction parameters influencing the extraction efficiency were optimized through response surface methodology using the Box-Behnken design. The proposed method achieved good linearity within the concentration range of 0.15-250 ng L(-1) PCBs, low limits of detection (0.04-0.09 ng L(-1), S/N=3:1), good repeatability of the extractions (relative standard deviation, spring waters were analyzed using the developed method. Results demonstrated that the hexagonal boron nitride-based material has significant potential as a sorbent for organic pollutant extraction from environmental water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Synthesis and photocatalytic activity of carbon spheres loaded Cu2O/Cu composites

    International Nuclear Information System (INIS)

    Li, Yinhui; Zhao, Mengyao; Zhang, Na; Li, Ruijuan; Chen, Jianxin

    2015-01-01

    Highlights: • Carbon spheres loaded Cu 2 O/Cu composites are obtained by hydrothermal process. • Cu 2 O/Cu nanocrystals grow on the surface of carbon spheres. • The composites with core–shell structure show highly photo-catalytic activity. • The composites can degrade methyl orange under simulated solar light irradiation. • The composites can be used to treat dye wastewater or organic pollutants. - Abstract: In this work, using amylose as carbon source and cupric acetate as copper source, carbon spheres loaded Cu 2 O/Cu composites were obtained by hydrothermal synthesis. The effects of the molar ratios between glucose and Cu(II), and hydrothermal time on the morphology and sizes of the composites were investigated. The result of photocatalytic experiments demonstrated that the composites could degrade methyl orange in aqueous solution under simulated solar light irradiation. The highest degradation rate was achieved to 93.83% when the composites were prepared by hydrothermal synthesis at 180 °C for 16 h and the molar ratio between glucose and Cu(II) was 10/1. The composites, as new and promising materials, can be used to treat dye wastewater or other organic pollutants

  14. Fabrication of polymeric hollow nanospheres, hollow nanocubes and hollow plates

    Science.gov (United States)

    Cheng, Daming; Xia, Haibing; Chan, Hardy Sze On

    2006-03-01

    A facile strategy for fabricating polypyrrole-chitosan (PPy-CS) hollow nanostructures with different shapes (sphere, cube and plate) and a wide range of sizes (from 35 to 600 nm) is described. These hollow structures have been fabricated using silver bromide as a single template material for polymer nucleation and growth. PPy-CS hollow nanostructures are formed by reaction with an etching agent to remove the core. These hollow nanostructures have been extensively characterized using various techniques such as TEM, FT-IR, UV-vis, and XRD.

  15. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Paul [General Electric Global Research, Niskayuna, NY (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, NY (United States); Narang, Kristi [General Electric Global Research, Niskayuna, NY (United States); McCloskey, Pat [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); Ananthasayanam, Balajee [General Electric Global Research, Niskayuna, NY (United States); Howson, Paul [General Electric Global Research, Niskayuna, NY (United States); Lee, Julia [General Electric Global Research, Niskayuna, NY (United States); Wroczynski, Ron [General Electric Global Research, Niskayuna, NY (United States); Stewart, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); McNally, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rownaghi, Ali [Georgia Inst. of Technology, Atlanta, GA (United States); Lu, Liu [Georgia Inst. of Technology, Atlanta, GA (United States); Koros, William [Georgia Inst. of Technology, Atlanta, GA (United States); Goizueta, Roberto [Georgia Inst. of Technology, Atlanta, GA (United States); Sethi, Vijay [Western Research Inst., Laramie, WY (United States)

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  16. Development of Novel ECTFE Coated PP Composite Hollow-Fiber Membranes

    Directory of Open Access Journals (Sweden)

    Sergio Santoro

    2016-09-01

    Full Text Available In this work composite hollow-fibers were prepared by dip-coating of commercial polypropylene (PP with a thin layer of ethylene–chlorotrifluoroethylene copolymer (ECTFE. The employment of N-methyl pyrrolidone (NMP as solvent improved the polymer processability favoring dip-coating at lower temperature (135 °C. Scanning electron microscopy (SEM analyses showed that after dip-coating the PP support maintained its microstructure, whereas a thin coated layer of ECTFE on the external surface of the PP hollow-fiber was clearly distinguishable. Membrane characterization evidenced the effects of the concentration of ECTFE in the dope-solution and the time of dip-coating on the thickness of ECTFE layer and membrane properties (i.e., contact angle and pore size. ECTFE coating decreased the surface roughness reducing, as a consequence, the hydrophobicity of the membrane. Moreover, increasing the ECTFE concentration and dip-coating time enabled the preparation of a thicker layer of ECTFE with low and narrow pore size that negatively affected the water transport. On the basis of the superior chemical resistance of ECTFE, ECTFE/PP composite hollow fibers could be considered as very promising candidates to be employed in membrane processes involving harsh conditions.

  17. Fabrication of nanocrystalline hydroxyapatite doped degradable composite hollow fiber for guided and biomimetic bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ning [Department of Bioengineering, Clemson University, Clemson, SC, 29634 (United States); Nichols, Heather L. [Department of Bioengineering, Clemson University, Clemson, SC, 29634 (United States); Tylor, Shila [Department of Bioengineering, Clemson University, Clemson, SC, 29634 (United States); Wen Xuejun [Department of Bioengineering, Clemson University, Clemson, SC, 29634 (United States)]. E-mail: xjwen@clemson.edu

    2007-04-15

    Natural bone tissue possesses a nanocomposite structure interwoven in a three-dimensional (3-D) matrix, which plays critical roles in conferring appropriate physical and biological properties to the bone tissue. Single type of material may not be sufficient to mimic the composition, structure and properties of native bone, therefore, composite materials consisting of both polymers, bioceramics, and other inorganic materials have to be designed. Among a variety of candidate materials, polymer-nanoparticle composites appear most promising for bone tissue engineering applications because of superior mechanical properties, improved durability, and surface bioactivity when compared with conventional polymers or composites. The long term objective of this project is to use highly aligned, bioactive, biodegradable scaffold mimicking natural histological structure of human long bone, and to engineer and regenerate human long bone both in vitro and in vivo. In this study, bioactive, degradable, and highly permeable composite hollow fiber membranes (HFMs) were fabricated using a wet phase phase-inversion approach. The structure of the hollow fiber membranes was examined using scanning electron microscopy (SEM); degradation behavior was examined using weigh loss assay, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC); and bioactivity was evaluated with the amount of calcium deposition from the culture media onto HFM surface. Doping PLGA HFMs with nanoHA results in a more bioactive and slower degrading HFM than pure PLGA HFMs.

  18. Shape Engineering of Biomass-Derived Nanoparticles from Hollow Spheres to Bowls via Solvent-Induced Buckling.

    Science.gov (United States)

    Chen, Chunhong; Li, Xuefeng; Jiang, Deng; Wang, Zhe; Wang, Yong

    2018-06-19

    To realize the asymmetry for the hollow carbonaceous nanostructures remains to be a great challenge, especially when biomass is chosen as the carbon resource via hydrothermal carbonization (HTC). Herein, a simple and straightforward solvent induced buckling strategy is demonstrated for the synthesis of asymmetric spherical and bowllike carbonaceous nanomaterials. The formation of the bowllike morphology was attributed to the buckling of the spherical shells induced by the dissolution of the oligomers. The bowllike particles made by this solvent-driven approach demonstrated a well-controlled morphology and a uniform particle size of ~360 nm. The obtained nanospheres and nanobowls can be loaded with CoS2 nanoparticles to act as novel heterogeneous catalysts for the selective hydrogenation of aromatic nitro compounds. With the bowllike structure in hand, as expected, the CoS2/nanobowls catalyst showed good tolerance to a wide scope of reducible groups and afforded both high activity and selectivity in almost all the tested substrates (14). © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

    International Nuclear Information System (INIS)

    Braga, Tiago P.; Vasconcelos, Igor F.; Sasaki, Jose M.; Fabris, J.D.; Oliveira, Diana Q.L. de; Valentini, Antoninho

    2010-01-01

    Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

  20. Down-conversion emission of Ce3+-Tb3+ co-doped CaF2 hollow spheres and application for solar cells

    Science.gov (United States)

    Cheng, Yufei; Wang, Yongbo; Teng, Feng; Dong, Hua; Chen, Lida; Mu, Jianglong; Sun, Qian; Fan, Jun; Hu, Xiaoyun; Miao, Hui

    2018-03-01

    Luminescent downconversion is a promising way to harvest ultraviolet sunlight and transform it into visible light that can be absorbed by solar cells, and has potential to improve their photoelectric conversion efficiency. In this work, the uniform hollow spheres and well dispersed CaF2 phosphors doped with rare-earth Ce3+ and Tb3+ ions are prepared by a one-step hydrothermal synthesis method. Benefiting from the stronger ability of absorption and emission and excellent transparency property, we demonstrate that the application of the doped nanocrystals can efficiently improve visible light transmittance. The chosen phosphors are added in the SiO2 sols so as to get the anti-reflection coatings with wavelength conversion bi-functional films, promoting the optical transmittance in the visible and near-infrared range which matches with the range of the band gap energy of silicon semiconductor. Optimized photoelectric conversion efficiency of 14.35% and the external quantum efficiency over 70% from 450 to 950 nm are obtained through the silicon solar cells with 0.10 g phosphors coating. Compared with the pure glass devices, the photoelectric conversion efficiency is enhanced by 0.69%. This work indicates that fluorescent downconversion not only can serve as proof of principles for improving photoelectric conversion efficiency of solar cells but also may be helpful to practical application in the future.

  1. Microwave-Assisted Synthesis of NiCo2O4 Double-Shelled Hollow Spheres for High-Performance Sodium Ion Batteries

    Science.gov (United States)

    Zhang, Xiong; Zhou, Yanping; Luo, Bin; Zhu, Huacheng; Chu, Wei; Huang, Kama

    2018-03-01

    The ternary transitional metal oxide NiCo2O4 is a promising anode material for sodium ion batteries due to its high theoretical capacity and superior electrical conductivity. However, its sodium storage capability is severely limited by the sluggish sodiation/desodiation reaction kinetics. Herein, NiCo2O4 double-shelled hollow spheres were synthesized via a microwave-assisted, fast solvothermal synthetic procedure in a mixture of isopropanol and glycerol, followed by annealing. Isopropanol played a vital role in the precipitation of nickel and cobalt, and the shrinkage of the glycerol quasi-emulsion under heat treatment was responsible for the formation of the double-shelled nanostructure. The as-synthesized product was tested as an anode material in a sodium ion battery, was found to exhibit a high reversible specific capacity of 511 mAh g-1 at 100 mA g-1, and deliver high capacity retention after 100 cycles. [Figure not available: see fulltext.

  2. The use of additive ceramic hollow spheres on cement slurry to prevent lost circulation in formation `X' having low pressure fracture

    Science.gov (United States)

    Rita, Novia; Mursyidah, Syahindra, Michael

    2018-03-01

    When drilling, if the hydrostatic pressure is higher than formation pressure (fracture pressure) it will cause lost circulation during cementing process. To solve this problem, hydrostatic pressure of slurry can be decreased by lowering the slurry density by using some additives. Ceramic Hollow Spheres (CHS) is lightweight additive. This additive comes with low specific gravity so it can lowered the slurry density. When the low-density slurry used in cementing process, it can prevent low circulation and fractured formation caused by cement itself. Class G cement is used in this experiment with the standard density of this slurry is 15.8 ppg. With the addition of CHS, slurry density lowered to 12.5 ppg. CHS not only used to lower the slurry density, it also used to make the same properties with the standard slurry even the density has been lowered. Both thickening time and compressive strength have not change if the CHS added to the slurry. With addition of CHS, thickening time at 70 Bc reached in 03 hours 12 minutes. For the compressive strength, 2000 psi reached in 07 hours 07 minutes. Addition of CHS can save more time in cementing process of X formation.

  3. Urchin-like cobalt incorporated manganese oxide OMS-2 hollow spheres: Synthesis, characterization and catalytic degradation of RhB dye

    Science.gov (United States)

    Ahmed, Khalid Abdelazez Mohamed; Li, Buyi; Tan, Bien; Huang, Kaixun

    2013-01-01

    Urchin-like KxCoyMn8-yO16 hollow spheres assembled from nanoplate building blocks were successfully fabricated via a one-pot hydrothermal route using cobalt acetate and potassium permanganate as raw material. The products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrometer, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) measurement. The thermal stability and surface areas of cobalt ion in the manganese sites of KMn8O16 structures were clearly evidenced by TGA and N2 adsorption-desorption isotherms curves. Based on time depended experiment results, a possible formation mechanism for this structures was proposed. The catalytic degradation of Rhodamine B (RhB) on KxCoyMn8-yO16 materials has, therefore been dependent for the molar precursor ratio and specific surface area of the as-fabricated products. UV-vis, LC-MS and barium hydroxide methods were utilized to monitor the temporal course of the catalytic reaction.

  4. Hierarchical cobalt poly-phosphide hollow spheres as highly active and stable electrocatalysts for hydrogen evolution over a wide pH range

    Science.gov (United States)

    Wu, Tianli; Pi, Mingyu; Wang, Xiaodeng; Guo, Weimeng; Zhang, Dingke; Chen, Shijian

    2018-01-01

    Exploring highly-efficient and low-cost non-noble metal electrocatalyst toward the hydrogen evolution reaction (HER) is highly desired for renewable energy system but remains challenging. In this work, three dimensional hierarchical porous cobalt poly-phosphide hollow spheres (CoP3 HSs) were prepared by topotactic phosphidation of the cobalt-based precursor via vacuum encapsulation technique. As a porous HER cathode, the CoP3 HSs delivers remarkable electrocatalytic performance over the wide pH range. It needs overpotentials of -69 mV and -118 mV with a small Tafel slope of 51 mV dec-1 to obtain current densities of 10 mA cm-2 and 50 mA cm-2, respectively, and maintains its electrocatalytic performance over 30 h in acidic solution. In addition, CoP3 also exhibit superior electrocatalytic performance and stability under neutral and alkaline conditions for the HER. Both experimental measurements and density functional theory (DFT) calculations are performed to explore the mechanism behind the excellent HER performance. The results of our study make the porous CoP3 HSs as a promising electrocatalyst for practical applications toward energy conversion system and present a new way for designing and fabricating HER electrodes through high degree of phosphorization and nano-porous architecture.

  5. SnO2@C@VO2 Composite Hollow Nanospheres as an Anode Material for Lithium-Ion Batteries.

    Science.gov (United States)

    Guo, Wenbin; Wang, Yong; Li, Qingyuan; Wang, Dongxia; Zhang, Fanchao; Yang, Yiqing; Yu, Yang

    2018-05-02

    Porous SnO 2 @C@VO 2 composite hollow nanospheres were ingeniously constructed through the combination of layer-by-layer deposition and redox reaction. Moreover, to optimize the electrochemical properties, SnO 2 @C@VO 2 composite hollow nanospheres with different contents of the external VO 2 were also studied. On the one hand, the elastic and conductive carbon as interlayer in the SnO 2 @C@VO 2 composite can not only buffer the huge volume variation during repetitive cycling but also effectively improve electronic conductivity and enhance the utilizing rate of SnO 2 and VO 2 with high theoretical capacity. On the other hand, hollow nanostructures of the composite can be consolidated by the multilayered nanocomponents, resulting in outstanding cyclic stability. In virtue of the above synergetic contribution from individual components, SnO 2 @C@VO 2 composite hollow nanospheres exhibit a large initial discharge capacity (1305.6 mAhg -1 ) and outstanding cyclic stability (765.1 mAhg -1 after 100 cycles). This design of composite hollow nanospheres may be extended to the synthesis of other nanomaterials for electrochemical energy storage.

  6. Structural dynamics of shroudless, hollow fan blades with composite in-lays

    Science.gov (United States)

    Aiello, R. A.; Hirschbein, M. S.; Chamis, C. C.

    1982-01-01

    Structural and dynamic analyses are presented for a shroudless, hollow titanium fan blade proposed for future use in aircraft turbine engines. The blade was modeled and analyzed using the composite blade structural analysis computer program (COBSTRAN); an integrated program consisting of mesh generators, composite mechanics codes, NASTRAN, and pre- and post-processors. Vibration and impact analyses are presented. The vibration analysis was conducted with COBSTRAN. Results show the effect of the centrifugal force field on frequencies, twist, and blade camber. Bird impact analysis was performed with the multi-mode blade impact computer program. This program uses the geometric model and modal analysis from the COBSTRAN vibration analysis to determine the gross impact response of the fan blades to bird strikes. The structural performance of this blade is also compared to a blade of similar design but with composite in-lays on the outer surface. Results show that the composite in-lays can be selected (designed) to substantially modify the mechanical performance of the shroudless, hollow fan blade.

  7. Optimization of the Photoanode of CdS Quantum Dot-Sensitized Solar Cells Using Light-Scattering TiO2 Hollow Spheres

    Science.gov (United States)

    Marandi, Maziar; Rahmani, Elham; Ahangarani Farahani, Farzaneh

    2017-12-01

    CdS quantum dot-sensitized solar cells (QDSCs) have been fabricated and their photoanode optimized by altering the thickness of the photoelectrode and CdS deposition conditions and applying a ZnS electron-blocking layer and TiO2 hollow spheres. Hydrothermally grown TiO2 nanocrystals (NCs) with dominant size of 20 nm were deposited as a sublayer in the photoanode with thickness in the range from 5 μm to 10 μm using a successive ionic layer adsorption and reaction (SILAR) method. The number of deposition cycles was altered over a wide range to obtain optimized sensitization. Photoanode thickness and number of CdS sensitization cycles around the optimum values were selected and used for ZnS deposition. ZnS overlayers were also deposited on the surface of the photoanodes using different numbers of cycles of the SILAR process. The best QDSC with the optimized photoelectrode demonstrated a 153% increase in efficiency compared with a similar cell with ZnS-free photoanode. Such bilayer photoelectrodes were also fabricated with different thicknesses of TiO2 sublayers and one overlayer of TiO2 hollow spheres (HSs) with external diameter of 500 nm fabricated by liquid-phase deposition with carbon spheres as template. The optimization was performed by changing the photoanode thickness using a wide range of CdS sensitizing cycles. The maximum energy conversion efficiency was increased by about 77% compared with a similar cell with HS-free photoelectrode. The reason was considered to be the longer path length of the incident light inside the photoanode and greater light absorption. A ZnS blocking layer was overcoated on the surface of the bilayer photoanode with optimized thickness. The number of CdS sensitization cycles was also changed around the optimized value to obtain the best QDSC performance. The number of ZnS deposition cycles was also altered in a wide range for optimization of the photovoltaic performance. It was shown that the maximum efficiency was increased by

  8. Improvements in processing characteristics and engineering properties of wood flour-filled high density polyethylene composite sheeting in the presence of hollow glass microspheres

    Science.gov (United States)

    Baris Yalcin; Steve E Amos; Andrew S D Souza; Craig M Clemons; I Sedat Gunes; Troy K Ista

    2012-01-01

    Hollow glass microspheres were introduced into wood flour/high density polyethylene composites by melt compounding in a twin-screw extruder. The prepared composites were subsequently converted to extruded profiles in order to obtain composite sheeting. The presence of hollow glass microspheres highly reduced the density of the extruded sheets down to 0.9 g/cc, while...

  9. A numerical approximation to the elastic properties of sphere-reinforced composites

    Science.gov (United States)

    Segurado, J.; Llorca, J.

    2002-10-01

    Three-dimensional cubic unit cells containing 30 non-overlapping identical spheres randomly distributed were generated using a new, modified random sequential adsortion algorithm suitable for particle volume fractions of up to 50%. The elastic constants of the ensemble of spheres embedded in a continuous and isotropic elastic matrix were computed through the finite element analysis of the three-dimensional periodic unit cells, whose size was chosen as a compromise between the minimum size required to obtain accurate results in the statistical sense and the maximum one imposed by the computational cost. Three types of materials were studied: rigid spheres and spherical voids in an elastic matrix and a typical composite made up of glass spheres in an epoxy resin. The moduli obtained for different unit cells showed very little scatter, and the average values obtained from the analysis of four unit cells could be considered very close to the "exact" solution to the problem, in agreement with the results of Drugan and Willis (J. Mech. Phys. Solids 44 (1996) 497) referring to the size of the representative volume element for elastic composites. They were used to assess the accuracy of three classical analytical models: the Mori-Tanaka mean-field analysis, the generalized self-consistent method, and Torquato's third-order approximation.

  10. Sound Absorption Properties Of Single-Hole Hollow Polyester Fiber Reinforced Hydrogenated Carboxyl Nitrile Rubber Composites

    Directory of Open Access Journals (Sweden)

    Jie Hong

    2017-09-01

    Full Text Available A series of single-hole hollow polyester fiber (SHHPF reinforced hydrogenated carboxyl nitrile rubber (HXNBR composites were fabricated. In this study, the sound absorption property of the HXNBR/SHHPF composite was tested in an impedance tube, the composite morphology was characterized by scanning electron microscope (SEM, and the tensile mechanical property was measured by strength tester. The results demonstrated that a remarkable change in sound absorption can be observed by increasing the SHHPF content from 0% to 40%. In the composite with 40% SHHPF in 1 mm thickness, the sound absorption coefficient reached 0.671 at 2,500 Hz; the effective bandwidth was 1,800-2,500 Hz for sound absorption coefficient larger than 0.2. But the sound absorption property of the composite deteriorated when the SHHPF content increased to 50% in 1 mm thickness. While with 20% SHHPF proportion, the sound absorption property was improved by increasing the thickness of composites from 1 to 5 mm. Compared with the pure HXNBR of the same thickness, the tensile mechanical property of the composite improved significantly by increasing the SHHPF proportion. As a lightweight composite with excellent sound absorption property, the HXNBR/SHHPF composite has potential practical application value in the fields of engineering.

  11. Analysis of the Dynamic Behavior of a Rotating Composite Hollow Shaft

    Directory of Open Access Journals (Sweden)

    Aldemir Ap Cavalini Jr

    Full Text Available Abstract In the present paper, a simplified homogenized beam theory is used in the context of a numerical investigation regarding the dynamic behavior of a rotating composite hollow shaft. For this aim, a horizontal flexible composite shaft and a rigid disc form the considered simple supported rotating system. The mathematical model of the rotor is derived from the Lagrange’s equation and the Rayleigh-Ritz method, which is obtained from the strain and kinetic energies of the disc and shaft, and the mass unbalance. In this case, a convergence procedure is carried out in terms of the vibration modes to obtain a representative model for the rotor system. Therefore, the proposed analysis is performed in both frequency and time domains, in which the frequency response functions, the unbalance responses, the Campbell diagram, and the orbits are numerically determined. Additionally, the instability threshold of the rotor system is obtained. This study illustrates the convenience of the composite hollow shafts for rotor dynamics applications.

  12. Influence of the shell thickness and charge distribution on the effective interaction between two like-charged hollow spheres.

    Science.gov (United States)

    Angelescu, Daniel G; Caragheorgheopol, Dan

    2015-10-14

    The mean-force and the potential of the mean force between two like-charged spherical shells were investigated in the salt-free limit using the primitive model and Monte Carlo simulations. Apart from an angular homogeneous distribution, a discrete charge distribution where point charges localized on the shell outer surface followed an icosahedral arrangement was considered. The electrostatic coupling of the model system was altered by the presence of mono-, trivalent counterions or small dendrimers, each one bearing a net charge of 9 e. We analyzed in detail how the shell thickness and the radial and angular distribution of the shell charges influenced the effective interaction between the shells. We found a sequence of the potential of the mean force similar to the like-charged filled spheres, ranging from long-range purely repulsive to short-range purely attractive as the electrostatic coupling increased. Both types of potentials were attenuated and an attractive-to-repulsive transition occurred in the presence of trivalent counterions as a result of (i) thinning the shell or (ii) shifting the shell charge from the outer towards the inner surface. The potential of the mean force became more attractive with the icosahedrally symmetric charge model, and additionally, at least one shell tended to line up with 5-fold symmetry axis along the longest axis of the simulation box at the maximum attraction. The results provided a basic framework of understanding the non-specific electrostatic origin of the agglomeration and long-range assembly of the viral nanoparticles.

  13. Dual-shell hollow polyaniline/sulfur-core/polyaniline composites improving the capacity and cycle performance of lithium–sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    An, Yanling; Wei, Pan; Fan, Meiqiang, E-mail: fanmeiqiang@126.com; Chen, Da; Chen, Haichao; Ju, QiangJian; Tian, Guanglei; Shu, Kangying

    2016-07-01

    Highlights: • A dual core-shell hPANI/S/PANI composite was prepared in situ synthesis. • Cycle performance of the hPANI/S/PANI composite was enhanced. • The improvement was due to fine sulfur particles wrapped by two PANI films. • Some positive effects were elaborated. - Abstract: In this study, a dual-shell hollow polyaniline/sulfur-core/polyaniline (hPANI/S/PANI) composite was prepared by successively depositing PANI, S, and PANI on the surface of a template silicon sphere. The electrochemical properties of this composite were evaluated using a lithium plate as an anode in lithium/sulfur cells. The hPANI/S/PANI composite showed a discharge capacity of 572.2 mAh g{sup −1} after 214 cycles at 0.1 C, and the Coulombic efficiency was above 87% in the whole charge/discharge cycle. The improved cycle property of the hPANI/S/PANI composite can be ascribed to the fine sulfur particles homogeneously deposited on the PANI surface and sprawled inside the two PANI layers during the charge/discharge cycle. This behavior stabilized the nanostructure of sulfur and enhanced its conductivity.

  14. Electrochemical properties of CuO hollow nanopowders prepared from formless Cu–C composite via nanoscale Kirkendall diffusion process

    Energy Technology Data Exchange (ETDEWEB)

    Won, Jong Min [Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713 (Korea, Republic of); Kim, Jong Hwa [Daegu Center, Korea Basic Science Institute, 80 Daehakro Bukgu, Daegu 702-701 (Korea, Republic of); Choi, Yun Ju [Suncheon Center, Korea Basic Science Institute, Suncheon 540-742 (Korea, Republic of); Cho, Jung Sang [Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713 (Korea, Republic of); Kang, Yun Chan, E-mail: yckang@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713 (Korea, Republic of)

    2016-06-25

    Hollow CuO nanopowders are prepared using a simple spray drying process that relied on nanoscale Kirkendall diffusion; these nanopowders have potential applications in lithium-ion batteries. Citric acid is used as both the carbon source material and chelating agent and plays a key role in the preparation of the hollow nanopowders. The formless Cu–C composite that formed as an intermediate product transforms into slightly aggregated CuO hollow nanopowders after post-treatment at 300 and 400 °C under an air atmosphere. The CuO hollow nanopowders exhibit higher initial discharge capacities and better cycling performances than those of the filled-structured CuO nanopowders, which are prepared at a post-treatment temperature of 500 °C under an air atmosphere. The discharge capacities of the CuO nanopowders post-treated at 300, 400, and 500 °C for the 150{sup th} cycle at a current density of 1 A g{sup −1} are 793, 632, and 464 mA h g{sup −1}, respectively, and their capacity retentions calculated from the maximum discharge capacities are 88, 80, and 73%, respectively. The CuO nanopowders with hollow structures exhibit better structural stability for repeated lithium insertion and desertion processes than those with filled structures. - Highlights: • Hollow CuO nanopowders are prepared using a simple spray drying process. • Cu–C composite transforms into CuO hollow nanopowders by Kirkendall diffusion. • Hollow CuO nanopowders show good electrochemical properties for lithium-ion storage.

  15. Non-conductive nanomaterial enhanced electrochemical response in stripping voltammetry: The use of nanostructured magnesium silicate hollow spheres for heavy metal ions detection.

    Science.gov (United States)

    Xu, Ren-Xia; Yu, Xin-Yao; Gao, Chao; Jiang, Yu-Jing; Han, Dong-Dong; Liu, Jin-Huai; Huang, Xing-Jiu

    2013-08-06

    Nanostructured magnesium silicate hollow spheres, one kind of non-conductive nanomaterials, were used in heavy metal ions (HMIs) detection with enhanced performance for the first time. The detailed study of the enhancing electrochemical response in stripping voltammetry for simultaneous detection of ultratrace Cd(2+), Pb(2+), Cu(2+) and Hg(2+) was described. Electrochemical properties of modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The operational parameters which have influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH value, and deposition time were carefully studied. The anodic stripping voltammetric performance toward HMIs was evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The detection limits achieved (0.186nM, 0.247nM, 0.169nM and 0.375nM for Cd(2+), Pb(2+), Cu(2+) and Hg(2+)) are much lower than the guideline values in drinking water given by the World Health Organization (WHO). In addition, the interference and stability of the modified electrode were also investigated under the optimized conditions. An interesting phenomenon of mutual interference between different metal ions was observed. Most importantly, the sensitivity of Pb(2+) increased in the presence of certain concentrations of other metal ions, such as Cd(2+), Cu(2+) and Hg(2+) both individually and simultaneously. The proposed electrochemical sensing method is thus expected to open new opportunities to broaden the use of SWASV in analysis for detecting HMIs in the environment. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Foam behavior of solid glass spheres – Zn22Al2Cu composites under compression stresses

    International Nuclear Information System (INIS)

    Aragon-Lezama, J.A.; Garcia-Borquez, A.; Torres-Villaseñor, G.

    2015-01-01

    Solid glass spheres – Zn22Al2Cu composites, having different densities and microstructures, were elaborated and studied under compression. Their elaboration process involves alloy melting, spheres submersion into the liquid alloy and finally air cooling. The achieved composites with densities 2.6884, 2.7936 and 3.1219 g/cm 3 were studied in casting and thermally induced, fine-grain matrix microstructures. Test samples of the composites were compressed at a 10 −3 s −1 strain rate, and their microstructure characterized before and after compression by using optical and scanning electron microscopes. Although they exhibit different compression behavior depending on their density and microstructure, all of them show an elastic region at low strains, reach their maximum stress (σ max ) at hundreds of MPa before the stress fall or collapse up to a lowest yield point (LYP), followed by an important plastic deformation at nearly constant stress (σ p ): beyond this plateau, an extra deformation can be limitedly reached only by a significant stress increase. This behavior under compression stresses is similar to that reported for metal foams, being the composites with fine microstructure which nearest behave to metal foams under this pattern. Nevertheless, the relative values of the elastic modulus, and maximum and plateau stresses do not follow the Ashby equations by changing the relative density. Generally, the studied composites behave as foams under compression, except for their peculiar parameters values (σ max , LYP, and σ p )

  17. Complex Hollow Nanostructures: Synthesis and Energy-Related Applications.

    Science.gov (United States)

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

    2017-04-01

    Hollow nanostructures offer promising potential for advanced energy storage and conversion applications. In the past decade, considerable research efforts have been devoted to the design and synthesis of hollow nanostructures with high complexity by manipulating their geometric morphology, chemical composition, and building block and interior architecture to boost their electrochemical performance, fulfilling the increasing global demand for renewable and sustainable energy sources. In this Review, we present a comprehensive overview of the synthesis and energy-related applications of complex hollow nanostructures. After a brief classification, the design and synthesis of complex hollow nanostructures are described in detail, which include hierarchical hollow spheres, hierarchical tubular structures, hollow polyhedra, and multi-shelled hollow structures, as well as their hybrids with nanocarbon materials. Thereafter, we discuss their niche applications as electrode materials for lithium-ion batteries and hybrid supercapacitors, sulfur hosts for lithium-sulfur batteries, and electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. The potential superiorities of complex hollow nanostructures for these applications are particularly highlighted. Finally, we conclude this Review with urgent challenges and further research directions of complex hollow nanostructures for energy-related applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Outer-selective thin film composite (TFC) hollow fiber membranes for osmotic power generation

    KAUST Repository

    Le, Ngoc Lieu

    2016-01-14

    The pressure-retarded osmosis (PRO) process is a green technique for power generation to respond the world\\'s need of energy sustainability. In this study, we have developed the vital component of the process, i.e. membrane, in the configuration of the outer-selective thin-film composite (TFC) hollow fiber, which is more practical than other configurations in the real applications. The support layer morphology and the formation of the selective polyamide layer have been optimized for a good PRO performance. The results show that the bore fluid with higher amount of the solvent N-methyl-2-pyrrolidone leads to full finger-like hollow fibers, which provide higher flux but lower pressure tolerance. The addition of higher amount of diethylene glycol into the dope solution, improves the pore formation and suppresses the macrovoid formation, while properly lowering the take-up speed increases their wall thickness and pressure tolerance. A simple alcohol-pre-wetting approach on the fiber support leads to a smooth and thin polyamide layer, which is favorable for a high water flux and power density. Its efficiency follows this order: n-propanol>ethanol>methanol>water. The n-propanol pre-wetted TFC membrane can tolerate 17 bar with a peak power density of 9.59 W/m2 at room temperature, using 1 M NaCl solution as the draw solution and DI water as feed. This work demonstrates the potential of outer-selective TFC hollow fiber membranes for energy conversion via PRO process, provides useful database to fabricate suitable support morphology and raise a simple technique to practically form a thin and smooth polyamide layer.

  19. Molten-droplet synthesis of composite CdSe hollow nanoparticles

    KAUST Repository

    Gullapalli, Sravani; Grider, Jason M.; Bagaria, Hitesh G.; Lee, Kyusung; Cho, Minjung; Colvin, Vicki L.; Jabbour, Ghassan E.; Wong, Michael

    2012-01-01

    Many colloidal synthesis routes are not scalable to high production rates, especially for nanoparticles of complex shape or composition, due to precursor expense and hazards, low yields, and the large number of processing steps. The present work describes a strategy to synthesize hollow nanoparticles (HNPs) out of metal chalcogenides, based on the slow heating of a low-melting-point metal salt, an elemental chalcogen, and an alkylammonium surfactant in octadecene solvent. The synthesis and characterization of CdSe HNPs with an outer diameter of 15.6 ± 3.5 nm and a shell thickness of 5.4 ± 0.9 nm are specifically detailed here. The HNP synthesis is proposed to proceed with the formation of alkylammonium-stabilized nano-sized droplets of molten cadmium salt, which then come into contact with dissolved selenium species to form a CdSe shell at the droplet surface. In a reaction-diffusion mechanism similar to the nanoscale Kirkendall effect it is speculated that the cadmium migrates outwardly through this shell to react with more selenium, causing the CdSe shell to thicken. The proposed CdSe HNP structure comprises a polycrystalline CdSe shell coated with a thin layer of amorphous selenium. Photovoltaic device characterization indicates that HNPs have improved electron transport characteristics compared to standard CdSe quantum dots, possibly due to this selenium layer. The HNPs are colloidally stable in organic solvents even though carboxylate, phosphine, and amine ligands are absent; stability is attributed to octadecene-selenide species bound to the particle surface. This scalable synthesis method presents opportunities to generate hollow nanoparticles with increased structural and compositional variety. © 2012 IOP Publishing Ltd.

  20. Molten-droplet synthesis of composite CdSe hollow nanoparticles

    KAUST Repository

    Gullapalli, Sravani

    2012-11-16

    Many colloidal synthesis routes are not scalable to high production rates, especially for nanoparticles of complex shape or composition, due to precursor expense and hazards, low yields, and the large number of processing steps. The present work describes a strategy to synthesize hollow nanoparticles (HNPs) out of metal chalcogenides, based on the slow heating of a low-melting-point metal salt, an elemental chalcogen, and an alkylammonium surfactant in octadecene solvent. The synthesis and characterization of CdSe HNPs with an outer diameter of 15.6 ± 3.5 nm and a shell thickness of 5.4 ± 0.9 nm are specifically detailed here. The HNP synthesis is proposed to proceed with the formation of alkylammonium-stabilized nano-sized droplets of molten cadmium salt, which then come into contact with dissolved selenium species to form a CdSe shell at the droplet surface. In a reaction-diffusion mechanism similar to the nanoscale Kirkendall effect it is speculated that the cadmium migrates outwardly through this shell to react with more selenium, causing the CdSe shell to thicken. The proposed CdSe HNP structure comprises a polycrystalline CdSe shell coated with a thin layer of amorphous selenium. Photovoltaic device characterization indicates that HNPs have improved electron transport characteristics compared to standard CdSe quantum dots, possibly due to this selenium layer. The HNPs are colloidally stable in organic solvents even though carboxylate, phosphine, and amine ligands are absent; stability is attributed to octadecene-selenide species bound to the particle surface. This scalable synthesis method presents opportunities to generate hollow nanoparticles with increased structural and compositional variety. © 2012 IOP Publishing Ltd.

  1. Enhanced electrochemical performance of different morphological C/LiMnPO4 nanoparticles from hollow-sphere Li3PO4 precursor via a delicate polyol-assisted hydrothermal method

    Science.gov (United States)

    Cui, Yu-Ting; Xu, Ning; Kou, Li-Qin; Wu, Meng-Tao; Chen, Li

    2014-03-01

    With the hollow-sphere Li3PO4 as precursor, a delicate polyol-assisted hydrothermal method is devised to synthesize high-performance LiMnPO4. Orthorhombic shaped, irregular flaky shaped and sphere-like LiMnPO4 are sequentially prepared by decreasing the water-diethylene glycol (DEG) ratio. The capacity, cycling stability and rate performance of all samples prepared by the new synthesis method are improved significantly. And the C/LiMnPO4 with irregular flaky shape exhibits a capacity of 154.1 mA h g-1 at C/20, 147.4 mA h g-1 at C/10 and 102.5 mA h g-1 at 2 C, which is the best performance ever reported for LiMnPO4 active material with similar carbon additives.

  2. Design and fabrication of inner-selective thin-film composite (TFC) hollow fiber modules for pressure retarded osmosis (PRO)

    KAUST Repository

    Wan, Chun Feng; Li, Bofan; Yang, Tianshi; Chung, Neal Tai-Shung

    2016-01-01

    Pressure retarded osmosis (PRO) is a promising technology to harvest the renewable osmotic energy from salinity gradients. There are great progresses in the fabrication of PRO membranes in the last decade. Thin-film composite (TFC) hollow fibers have been widely studied and demonstrated superior performance. However, the lack of effective TFC hollow fiber modules hinders the commercialization of the PRO technology. Knowledge and experiences to fabricate TFC hollow fiber modules remain limited in the open literature. In this study, we aim to reveal the engineering and science on how to fabricate TFC hollow fiber modules including the formation of inner-selective polyamide layers and the repair of leakages. TFC-PES hollow fiber modules with 30% and 50% packing densities have been successfully fabricated, showing peak power densities of 20.0 W/m2 and 19.4 W/m2, respectively, at 20 bar using 1 M NaCl solution and DI water as feeds. The modules may be damaged during handling and high pressure testing. The repaired modules have a power density of 18.2 W/m2, 91% of the power densities of the undamaged ones. This study would make up the gap between TFC membrane fabrication and TFC membrane module fabrication in the membrane industry. © 2016 Elsevier B.V.

  3. Design and fabrication of inner-selective thin-film composite (TFC) hollow fiber modules for pressure retarded osmosis (PRO)

    KAUST Repository

    Wan, Chun Feng

    2016-08-03

    Pressure retarded osmosis (PRO) is a promising technology to harvest the renewable osmotic energy from salinity gradients. There are great progresses in the fabrication of PRO membranes in the last decade. Thin-film composite (TFC) hollow fibers have been widely studied and demonstrated superior performance. However, the lack of effective TFC hollow fiber modules hinders the commercialization of the PRO technology. Knowledge and experiences to fabricate TFC hollow fiber modules remain limited in the open literature. In this study, we aim to reveal the engineering and science on how to fabricate TFC hollow fiber modules including the formation of inner-selective polyamide layers and the repair of leakages. TFC-PES hollow fiber modules with 30% and 50% packing densities have been successfully fabricated, showing peak power densities of 20.0 W/m2 and 19.4 W/m2, respectively, at 20 bar using 1 M NaCl solution and DI water as feeds. The modules may be damaged during handling and high pressure testing. The repaired modules have a power density of 18.2 W/m2, 91% of the power densities of the undamaged ones. This study would make up the gap between TFC membrane fabrication and TFC membrane module fabrication in the membrane industry. © 2016 Elsevier B.V.

  4. Foam behavior of solid glass spheres – Zn22Al2Cu composites under compression stresses

    Energy Technology Data Exchange (ETDEWEB)

    Aragon-Lezama, J.A., E-mail: alja@correo.azc.uam.mx [Departamento de Materiales, Universidad Autónoma Metropolitana-A, Avenida San Pablo 180, Colonia Reynosa Tamaulipas, 02200 México, D.F., México (Mexico); Garcia-Borquez, A., E-mail: a.garciaborquez@yahoo.com.mx [Ciencia de Materiales, ESFM – Instituto Politécnico Nacional, Edif. 9, Unid. Prof. A. Lopez Mateos, Colonia Lindavista, 07738 México, D.F., México (Mexico); Torres-Villaseñor, G., E-mail: gtorres@unam.mx [Departamento de Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo., P 70-360, México, D.F., México (Mexico)

    2015-06-25

    Solid glass spheres – Zn22Al2Cu composites, having different densities and microstructures, were elaborated and studied under compression. Their elaboration process involves alloy melting, spheres submersion into the liquid alloy and finally air cooling. The achieved composites with densities 2.6884, 2.7936 and 3.1219 g/cm{sup 3} were studied in casting and thermally induced, fine-grain matrix microstructures. Test samples of the composites were compressed at a 10{sup −3} s{sup −1} strain rate, and their microstructure characterized before and after compression by using optical and scanning electron microscopes. Although they exhibit different compression behavior depending on their density and microstructure, all of them show an elastic region at low strains, reach their maximum stress (σ{sub max}) at hundreds of MPa before the stress fall or collapse up to a lowest yield point (LYP), followed by an important plastic deformation at nearly constant stress (σ{sub p}): beyond this plateau, an extra deformation can be limitedly reached only by a significant stress increase. This behavior under compression stresses is similar to that reported for metal foams, being the composites with fine microstructure which nearest behave to metal foams under this pattern. Nevertheless, the relative values of the elastic modulus, and maximum and plateau stresses do not follow the Ashby equations by changing the relative density. Generally, the studied composites behave as foams under compression, except for their peculiar parameters values (σ{sub max}, LYP, and σ{sub p})

  5. A composite of hollow carbon nanospheres and sulfur-rich polymers for lithium-sulfur batteries

    Science.gov (United States)

    Zeng, Shao-Zhong; Yao, Yuechao; Zeng, Xierong; He, Qianjun; Zheng, Xianfeng; Chen, Shuangshuang; Tu, Wenxuan; Zou, Jizhao

    2017-07-01

    Lithium-sulfur batteries are the most promising candidates for future high-energy applications because of the unparalleled capacity of sulfur (1675 mAh g-1). However, lithium-sulfur batteries have limited cycle life and rate capability due to the dissolution of polysulfides and the extremely low electronic conductivity of sulfur. To solve these issues, various porous carbons including hollow carbon nanospheres (HCNs) have been used for improving the conductivity. However, these methods still suffer from polysulfides dissolution/loss owing to their weak physical adsorption to polysulfides. Herein, we introduced a covalent grafting route to composite the HCNs and the vulcanized trithiocyanuric acid (TTCA). The composite exhibits a high loading of the vulcanized TTCA by the HCNs with high surface area and large pore volume, and covalent bonds to sulfur, effectively depressing the dissolution of polysulfides. The first discharge capacity of the composite reaches 1430 mAh g-1 at 0.1 C and 1227 mAh g-1 at 0.2 C.

  6. Y2O3:Yb,Er@mSiO2-CuxS double-shelled hollow spheres for enhanced chemo-/photothermal anti-cancer therapy and dual-modal imaging

    Science.gov (United States)

    Yang, Dan; Yang, Guixin; Wang, Xingmei; Lv, Ruichan; Gai, Shili; He, Fei; Gulzar, Arif; Yang, Piaoping

    2015-07-01

    Multifunctional composites have gained significant interest due to their unique properties which show potential in biological imaging and therapeutics. However, the design of an efficient combination of multiple diagnostic and therapeutic modes is still a challenge. In this contribution, Y2O3:Yb,Er@mSiO2 double-shelled hollow spheres (DSHSs) with up-conversion fluorescence have been successfully prepared through a facile integrated sacrifice template method, followed by a calcination process. It is found that the double-shelled structure with large specific surface area and uniform shape is composed of an inner shell of luminescent Y2O3:Yb,Er and an outer mesoporous silica shell. Ultra small CuxS nanoparticles (about 2.5 nm) served as photothermal agents, and a chemotherapeutic agent (doxorubicin, DOX) was then attached onto the surface of mesoporous silica, forming a DOX-DSHS-CuxS composite. The composite exhibits high anti-cancer efficacy due to the synergistic photothermal therapy (PTT) induced by the attached CuxS nanoparticles and the enhanced chemotherapy promoted by the heat from the CuxS-based PTT when irradiated by 980 nm near-infrared (NIR) light. Moreover, the composite shows excellent in vitro and in vivo X-ray computed tomography (CT) and up-conversion fluorescence (UCL) imaging properties owing to the doped rare earth ions, thus making it possible to achieve the target of imaging-guided synergistic therapy.Multifunctional composites have gained significant interest due to their unique properties which show potential in biological imaging and therapeutics. However, the design of an efficient combination of multiple diagnostic and therapeutic modes is still a challenge. In this contribution, Y2O3:Yb,Er@mSiO2 double-shelled hollow spheres (DSHSs) with up-conversion fluorescence have been successfully prepared through a facile integrated sacrifice template method, followed by a calcination process. It is found that the double-shelled structure with large

  7. 3D hollow sphere Co3O4/MnO2-CNTs: Its high-performance bi-functional cathode catalysis and application in rechargeable zinc-air battery

    Directory of Open Access Journals (Sweden)

    Xuemei Li

    2017-07-01

    Full Text Available There has been a continuous need for high active, excellently durable and low-cost electrocatalysts for rechargeable zinc-air batteries. Among many low-cost metal based candidates, transition metal oxides with the CNTs composite have gained increasing attention. In this paper, the 3-D hollow sphere MnO2 nanotube-supported Co3O4 nanoparticles and its carbon nanotubes hybrid material (Co3O4/MnO2-CNTs have been synthesized via a simple co-precipitation method combined with post-heat treatment. The morphology and composition of the catalysts are thoroughly analyzed through SEM, TEM, TEM-mapping, XRD, EDX and XPS. In comparison with the commercial 20% Pt/C, Co3O4/MnO2, bare MnO2 nanotubes and CNTs, the hybrid Co3O4/MnO2-CNTs-350 exhibits perfect bi-functional catalytic activity toward oxygen reduction reaction and oxygen evolution reaction under alkaline condition (0.1 M KOH. Therefore, high cell performances are achieved which result in an appropriate open circuit voltage (∼1.47 V, a high discharge peak power density (340 mW cm−2 and a large specific capacity (775 mAh g−1 at 10 mA cm−2 for the primary Zn-air battery, a small charge–discharge voltage gap and a high cycle-life (504 cycles at 10 mA cm−2 with 10 min per cycle for the rechargeable Zn-air battery. In particular, the simple synthesis method is suitable for a large-scale production of this bifunctional material due to a green, cost effective and readily available process. Keywords: Bi-functional catalyst, Oxygen reduction reaction, Oxygen evolution reaction, Activity and stability, Rechargeable zinc-air battery

  8. Ag/α-Fe2O3 hollow microspheres: Preparation and application for hydrogen peroxide detection

    Science.gov (United States)

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang; Zhang, Tingting; Guo, Tingting

    2015-09-01

    In this paper, we demonstrated a simple approach for preparing α-Fe2O3 hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe2O3 hollow spheres formation. Ag/α-Fe2O3 hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe2O3 hollow composites exhibited remarkable catalytic performance toward H2O2 reduction. The electrocatalytic activity mechanism of Ag/α-Fe2O3/GCE were discussed toward the reduction of H2O2 in this paper.

  9. Unit-Sphere Multiaxial Stochastic-Strength Model Applied to Anisotropic and Composite Materials

    Science.gov (United States)

    Nemeth, Noel, N.

    2013-01-01

    Models that predict the failure probability of brittle materials under multiaxial loading have been developed by authors such as Batdorf, Evans, and Matsuo. These "unit-sphere" models assume that the strength-controlling flaws are randomly oriented, noninteracting planar microcracks of specified geometry but of variable size. This methodology has been extended to predict the multiaxial strength response of transversely isotropic brittle materials, including polymer matrix composites (PMCs), by considering (1) flaw-orientation anisotropy, whereby a preexisting microcrack has a higher likelihood of being oriented in one direction over another direction, and (2) critical strength, or K (sub Ic) orientation anisotropy, whereby the level of critical strength or fracture toughness for mode I crack propagation, K (sub Ic), changes with regard to the orientation of the microstructure. In this report, results from finite element analysis of a fiber-reinforced-matrix unit cell were used with the unit-sphere model to predict the biaxial strength response of a unidirectional PMC previously reported from the World-Wide Failure Exercise. Results for nuclear-grade graphite materials under biaxial loading are also shown for comparison. This effort was successful in predicting the multiaxial strength response for the chosen problems. Findings regarding stress-state interactions and failure modes also are provided.

  10. Preparation of carbon nanotubes/epoxy resin composites by using hollow glass beads as the carrier

    International Nuclear Information System (INIS)

    Wu, X.F.; Zhao, Y.K.; Zhang, D.; Chen, T.B.; Ma, L.Y.

    2012-01-01

    Hollow glass beads had been utilized as the carrier to assist dispersion of carbon nanotubes in epoxy resin. Hollow glass beads were firstly aminated with gamma-aminopropyl-triethoxysilane, sencondly reacted with carboxyl-functionalized carbon nanotubes via an amidation reaction and susequently mixed with epoxy resin and hardener. The experimental results showed that carbon nanotubes could be loaded on the surfaces of hollow glass beads and approximately a monolayer of carbon nanotubes was formed when the weight ratio of hollow glass beads to carbon nanotubes was 100:5. Moreover, the dispersity of carbon nanotubes in the matrix was improved as compared to the control samples prepared by using a conventional mixing method. (author)

  11. Crystal nucleation in binary hard-sphere mixtures: the effect of order parameter on the cluster composition

    NARCIS (Netherlands)

    Ni, R.; Smallenburg, F.; Filion, L.C.; Dijkstra, M.

    2011-01-01

    We study crystal nucleation in a binary mixture of hard spheres and investigate the composition and size of the (non)critical clusters using Monte Carlo simulations. In order to study nucleation of a crystal phase in computer simulations, a one-dimensional order parameter is usually defined to

  12. Ag/α-Fe2O3 hollow microspheres: Preparation and application for hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang; Zhang, Tingting; Guo, Tingting

    2015-01-01

    In this paper, we demonstrated a simple approach for preparing α-Fe 2 O 3 hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe 2 O 3 hollow spheres formation. Ag/α-Fe 2 O 3 hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe 2 O 3 hollow composites exhibited remarkable catalytic performance toward H 2 O 2 reduction. The electrocatalytic activity mechanism of Ag/α-Fe 2 O 3 /GCE were discussed toward the reduction of H 2 O 2 in this paper. - Graphical abstract: Glucose is carbonized as carbon balls in the 180 °C hydrothermal carbonization process, which plays a role of a soft template. Carbon spherical shell is rich in many hydroxyls, which have good hydrophilicity and surface reactivity. When Fe(NO 3 ) 3 is added to the aqueous solution of Glucose, the hydrophilic -OH will adsorb Fe 3+ to form coordination compound by coordination bond. α-FeOOH is formed on the surface of carbon balls by hydrothermal reaction. After calcination at 500 °C, carbon spheres react with oxygen to form carbon dioxide, which disappears in the air. Meanwhile α-FeOOH is calcined to form α-Fe 2 O 3 hollow spheres.

  13. Multifunctional Roles of TiO 2 Nanoparticles for Architecture of Complex Core−Shells and Hollow Spheres of SiO 2 −TiO 2 −Polyaniline System

    KAUST Repository

    Wang, Dan Ping

    2009-10-27

    Nanoparticles are often used as seeds to grow one-dimensional nanomaterials or as core materials to prepare core-shell nanostructures. On the other hand, the presynthesized inorganic nanoparticles can also be used as starting building blocks to prepare inorganic-polymer nanocomposites. In this work, we explore the roles of metal-oxide nanoparticles (anatase TiO2) in the area of constructional synthesis of highly complex core-shell and hollow sphere nanostructures comprising SiO2, TiO2, and polyaniline (PAN). In particular, multifunctional roles of oleate-surfactant-protected TiO2 nanoparticles have been revealed in this study: they provide starting sites for polymerization of aniline on the surface of SiO2 mesospheres; they land on the inner surface of polyaniline shell to form a secondary material phase; they work as initial crystalline seeds for homogeneous growth of interior TiO2 shell; and they serve as primary nanobuilding blocks to form exterior TiO2 shell on the polyaniline via self-assembly. With the assistance of the TiO2 nanoparticles, a total of six complex core-shell and hollow sphere nanocomposites (SiO 2/TiO2, SiO2/TiO2/PAN, SiO 2/TiO2/PAN/TiO2, TiO2/PAN, TiO 2/PAN/TiO2, and TiO2/TiO2) have been made in this work through controlled self-assembly, templating growth, polymerization, and homogeneous seeded growth. Applicability of these nanostructures in photocatalytic applications has also been demonstrated by our preliminary investigations. The easy separation of used catalysts after reaction seems to be advantageous because of relatively large external diameters of the lightweight nanocomposites. © 2009 American Chemical Society.

  14. Removal of Pb(II) from wastewater using Al2O3-NaA zeolite composite hollow fiber membranes synthesized from solid waste coal fly ash.

    Science.gov (United States)

    Zhu, Li; Ji, Jiayou; Wang, Shulin; Xu, Chenxi; Yang, Kun; Xu, Man

    2018-09-01

    Al 2 O 3 -NaA zeolite composite hollow fiber membranes were successfully fabricated via hydrothermal synthesis by using industrial solid waste coal fly ash and porous Al 2 O 3 hollow fiber supports. The as-synthesized Al 2 O 3 -NaA zeolite composite hollow fiber membranes were then characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The hollow fiber membranes were used to remove lead ions (Pb(II), 50 mg L -1 ) from synthetic wastewater with a removal efficiency of 99.9% at 0.1 MPa after 12 h of filtration. This study showed that the Al 2 O 3 -NaA zeolite composite hollow fiber membranes (the pore size of the membrane was about 0.41 nm in diameter) synthesized from coal fly ash could be efficiently used for treating low concentration Pb(II) wastewater. It recycled solid waste coal fly ash not only to solve its environment problems, but also can produce high-value Al 2 O 3 -NaA zeolite composite hollow fiber membranes for separation application in treating wastewater containing Pb(II). Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Facile synthesis and characterization of ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yu [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); School of Environmental and Chemical Engineering, Dalian Jiaotong University, Dalian 116028 (China); Li, Xinyong, E-mail: xyli@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia); Zhao, Qidong; Hou, Yang [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Tade, Moses [Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia); Liu, Shaomin, E-mail: Shaomin.Liu@curtin.edu.au [Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres were successfully synthesized via a facile method. Black-Right-Pointing-Pointer Detailed structural, morphology and the phase composition were studied. Black-Right-Pointing-Pointer The incorporation of ZnFe{sub 2}O{sub 4} and {alpha}-Fe{sub 2}O{sub 3} gives an appropriate band gap value to utilize solar energy. -- Abstract: ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres were successfully fabricated via a facile one-pot solvothermal method, utilizing polyethylene glycol as soft template. X-ray diffraction and scanning electron microscopy analysis revealed that the prepared nanospheres with cubic spinel and rhombohedra composite structure had a uniform diameter of about 370 nm, and the hollow structure could be further confirmed by transmission electron microscopy. Energy dispersive X-ray, X-ray photoelectron spectroscopy and Fourier transform infrared techniques were also applied to characterize the elemental composition and chemical bonds in the hollow nanospheres. The ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres show attractive light absorption property for potential applications in electronics, optics, and catalysis.

  16. Hollow magnetic nano-CO3O4/polystyrene microspheres synthesized through radiation induced interfacial polymerization

    International Nuclear Information System (INIS)

    Zhang Wei; Wang Mozhen; Wang Shufeng; Zhang Zhicheng

    2010-01-01

    Co 3 O 4 nanoparticles (around 8 nm) were synthesized hydrothermally by dissolving Co 2+ in the mixture of ethanol and water, and then decorated with oleic acid to endow them with hydrophobic surface nature. After that, nano-particles were added into emulsion which consisted by sodium dodecyl sulfate, water, styrene and cetyl alcohol. Hollow magnetic composite spheres were prepared by irradiated the emulsion with γ-rays. The final products are thoroughly characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) techniques, which showed the formation of hollow magnetic composite spheres. The influence of addition dosage of nano-particles, sodium dodecyl sulfate and the types of nano-particles on the average size and shape of hollow composites were studied. The effects of nano-particles to the polymerization of styrene were studied by kinetics. Nano-particles are capsulated by polystyrene to form hollow composites, which confirmed by XPS results. Finally, magnetic property of hollow composites is compared with pure nano-Co 3 O 4 . (authors)

  17. A composite sphere assemblage model for porous oolitic rocks: Application to thermal conductivity

    Directory of Open Access Journals (Sweden)

    F. Chen

    2017-02-01

    Full Text Available The present work is devoted to the determination of linear effective thermal conductivity of porous rocks characterized by an assemblage of grains (oolites coated by a matrix. Two distinct classes of pores, i.e. micropores or intra oolitic pores (oolite porosity and mesopores or inter oolitic pores (inter oolite porosity, are taken into account. The overall porosity is supposed to be connected and decomposed into oolite porosity and matrix porosity. Within the framework of Hashin composite sphere assemblage (CSA models, a two-step homogenization method is developed. At the first homogenization step, pores are assembled into two layers by using self-consistent scheme (SCS. At the second step, the two porous layers constituting the oolites and the matrix are assembled by using generalized self-consistent scheme (GSCS and referred to as three-phase model. Numerical results are presented for data representative of a porous oolitic limestone. It is shown that the influence of porosity on the overall thermal conductivity of such materials may be significant.

  18. Development of Polysulfone Hollow Fiber Porous Supports for High Flux Composite Membranes: Air Plasma and Piranha Etching

    Directory of Open Access Journals (Sweden)

    Ilya Borisov

    2017-02-01

    Full Text Available For the development of high efficiency porous supports for composite membrane preparation, polysulfone (PSf hollow fiber membranes (outer diameter 1.57 mm, inner diameter 1.12 mm were modified by air plasma using the low temperature plasma treatment pilot plant which is easily scalable to industrial level and the Piranha etch (H2O2 + H2SO4. Chemical and plasma modification affected only surface layers and did not cause PSf chemical structure change. The modifications led to surface roughness decrease, which is of great importance for further thin film composite (TFC membranes fabrication by dense selective layer coating, and also reduced water and ethylene glycol contact angle values for modified hollow fibers surface. Furthermore, the membranes surface energy increased two-fold. The Piranha mixture chemical modification did not change the membranes average pore size and gas permeance values, while air plasma treatment increased pore size 1.5-fold and also 2 order enhanced membranes surface porosity. Since membranes surface porosity increased due to air plasma treatment the modified membranes were used as efficient supports for preparation of high permeance TFC membranes by using poly[1-(trimethylsilyl-1-propyne] as an example for selective layer fabrication.

  19. Graphene Spheres-CuO Nanoflowers Composites for Use as a High Performance Photocatalyst

    Directory of Open Access Journals (Sweden)

    Bin Zeng

    2016-03-01

    Full Text Available Graphene spheres decorated with CuO nanoflowers were successfully synthesized via a spray-drying method. Scanning-electron and transmission-electron microscopy were used to confirm that the graphene formed spherical structures and that the CuO nanoflowers were well dispersed on the surface of these graphene spheres. These novel nanocomposites had an enhanced photocatalytic performance, achieving a 95.2% decomposition of methyl orange after 15 min in the presence of H2O2 when irradiated by visible light. These nanocomposites performed much better than CuO powders alone.

  20. In situ fabrication of nickel aluminum-layered double hydroxide nanosheets/hollow carbon nanofibers composite as a novel electrode material for supercapacitors

    Science.gov (United States)

    He, Fang; Hu, Zhibiao; Liu, Kaiyu; Zhang, Shuirong; Liu, Hongtao; Sang, Shangbin

    2014-12-01

    This paper introduces a new design route to fabricate nickel aluminum-layered double hydroxide (NiAl-LDH) nanosheets/hollow carbon nanofibers (CNFs) composite through an in situ growth method. The NiAl-LDH thin layers which grow on hollow carbon nanofibers have an average thickness of 13.6 nm. The galvanostatic charge-discharge test of the NiAl-LDH/CNFs composite yields an impressive specific capacitance of 1613 F g-1 at 1 A g-1 in 6 M KOH solution, the composite shows a remarkable specific capacitance of 1110 F g-1 even at a high current density of 10 A g-1. Furthermore, the composite remains a specific capacitance of 1406 F g-1 after 1000 cycles at 2 A g-1, indicating the composite has excellent high-current capacitive behavior and good cycle stability in compared to pristine NiAl-LDH.

  1. SiO2/ZnO Composite Hollow Sub-Micron Fibers: Fabrication from Facile Single Capillary Electrospinning and Their Photoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Guanying Song

    2017-02-01

    Full Text Available In this work, SiO2/ZnO composite hollow sub-micron fibers were fabricated by a facile single capillary electrospinning technique followed by calcination, using tetraethyl orthosilicate (TEOS, polyvinylpyrrolidone (PVP and ZnO nanoparticles as raw materials. The characterization results of the scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FT-IR spectra indicated that the asprepared composite hollow fibers consisted of amorphous SiO2 and hexagonal wurtzite ZnO. The products revealed uniform tubular structure with outer diameters of 400–500 nm and wall thickness of 50–60 nm. The gases generated and the directional escaped mechanism was proposed to illustrate the formation of SiO2/ZnO composite hollow sub-micron fibers. Furthermore, a broad blue emission band was observed in the photoluminescence (PL of SiO2/ZnO composite hollow sub-micron fibers, exhibiting great potential applications as blue light-emitting candidate materials.

  2. Effect of admixed high-density polyethylene (HDPE) spheres on contraction stress and properties of experimental composites.

    Science.gov (United States)

    Ferracane, J L; Ferracane, L L; Braga, R R

    2003-07-15

    Additives that provide stress relief may be incorporated into dental composites to reduce contraction stress (CS). This study attempted to test the hypothesis that conventional fillers could be replaced by high-density polyethylene (HDPE) spheres in hybrid and nanofill composites to reduce CS, but with minimal effect on mechanical properties. Nanofill and hybrid composites were made from a Bis-GMA/TEGDMA resin having either all silica nanofiller or 75 wt.% strontium glass + 5 wt.% silica and replacing some of the nanofiller or the glass with 0%, 5% (hybrid only), 10% or 20 wt.% HDPE. The surface of the HDPE was either left untreated or had a reactive gas surface treatment (RGST). Contraction stress (CS) was monitored for 10 min in a tensilometer (n = 5) after light curing for 60 s at 390 mW/cm(2). Other specimens (n = 5) were light cured 40 s from two sides in a light-curing unit and aged 1 d in water before testing fracture toughness (K(Ic)), flexure strength (FS), and modulus (E). Results were analyzed by ANOVA with Tukey's multiple comparison test at p HDPE except for FS-10% HDPE hybrid (RGST higher). An increased level of HDPE reduced contraction stress for both types of composites. Flexure strength, modulus (hybrid only), and fracture toughness were also reduced as the concentration of HDPE increased. SEM showed evidence for HDPE debonding and plastic deformation during fracture of the hybrid composites. In conclusion, the addition of HDPE spheres reduces contraction stress in composites, either through stress relief or a reduction in elastic modulus. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 318-323, 2003

  3. Preparation of hollow Zn2SnO4 boxes@C/graphene ternary composites with a triple buffering structure and their electrochemical performance for lithium-ion batteries

    International Nuclear Information System (INIS)

    Huang, Haijian; Huang, Ying; Wang, Mingyue; Chen, Xuefang; Zhao, Yang; Wang, Ke; Wu, Haiwei

    2014-01-01

    Highlights: • A new hollow Zn 2 SnO 4 boxes@C/graphene ternary composites were synthesized through two hydrothermal processes followed by a calcined process for the first time. • The structure, morphology and electrochemical properties of the ternary composites were investigated by means of XRD, FTIR, Raman, BET, BJH, SEM, TEM, and electrochemical measurements. • The hollow Zn 2 SnO 4 boxes@C/graphene ternary composites were proved to have a triple buffering nanostructure. The hollow interior of the Zn 2 SnO 4 boxes, the carbon coating layer on the surface of the boxes and the 3D carbon network constructed by the graphene sheets can work together to effectively improve the electrochemical performance of the material. • The hollow Zn 2 SnO 4 boxes@C/graphene ternary composites show an enhanced electrochemical performance (726.9 mAh g −1 at a current density of 300 mA g −1 after 50 cycles) and high rate capability compared with the hollow Zn 2 SnO 4 boxes@graphene binary composites, the hollow Zn 2 SnO 4 boxes@C binary composites, the hollow Zn 2 SnO 4 boxes and the solid Zn 2 SnO 4 cubes. - Abstract: Hollow Zn 2 SnO 4 boxes@C/graphene ternary composites with a three-dimensional triple buffering structure are prepared by two hydrothermal processes followed by a calcined process. The structure, morphology and electrochemical properties of the ternary composites were investigated by means of XRD, FTIR, Raman, BET, BJH, SEM, TEM, and electrochemical measurements. The hollow Zn 2 SnO 4 boxes are coated with carbon layer and then supported by graphene sheets to form a 3D carbon conductive network. Compared with the hollow Zn 2 SnO 4 boxes@graphene binary composites, the hollow Zn 2 SnO 4 boxes@C binary composites, the hollow Zn 2 SnO 4 boxes and the solid Zn 2 SnO 4 cubes, the hollow Zn 2 SnO 4 boxes@C/graphene ternary composites show an enhanced electrochemical performance (726.9 mAh g −1 at a current density of 300 mA g −1 after 50 cycles) and high rate

  4. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    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.

  5. N-doped hollow urchin-like anatase TiO2@C composite as a novel anode for Li-ion batteries

    Science.gov (United States)

    Xing, Yalan; Wang, Shengbin; Fang, Baizeng; Song, Ge; Wilkinson, David P.; Zhang, Shichao

    2018-05-01

    N-doped hollow urchin-like anatase TiO2 spheres (HUTSs) with carbon coating (HUTS@C) are prepared through a facile and scalable hydrothermal reaction followed by coating of polypyrrole and carbonization. The HUTS is composed of radially grown anatase nanorods and possesses an enhanced percentage of exposed {001} facets compared with P25 TiO2 nanoparticles. After the carbon coating, the HUTS@C retains the hollow nanostructure although covered with an N-doped carbon layer. As an anode for Li-ion batteries, the HUTS@C delivers a higher capacity of 165.1 mAh g-1 at 1C after 200 cycles and better rate capability (111.7 mAh g-1 at 10C) than the HUTS. Further electrochemical studies reveal that the HUTS@C has a better electrochemical reversibility, lower charge-transfer resistance, and higher Li-ion diffusion coefficient due to its unique nanosctructure including the hollow core, anatase phase of TiO2 microspheres with high exposed {001} facets and the N-doped carbon layer, which facilitates mass transport and enhances electrical conductivity.

  6. Assembly of cerium(III)-stabilized polyoxotungstate nanoclusters with SeO{sub 3}{sup 2-}/TeO{sub 3}{sup 2-} templates. From single polyoxoanions to inorganic hollow spheres in dilute solution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei-Chao; Wang, Xin-Long; Shao, Kui-Zhan; Su, Zhong-Min; Wang, En-Bo [Institute of Functional Materials Chemistry, Key Laboratory of Polyoxometalate Science of Ministry of Education, Department of Chemistry, Northeast Normal University, Changchun (China); Li, Hao-Long [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University. Changchun (China)

    2013-08-12

    A versatile one-pot strategy was employed to synthesize three cerium(III)-stabilized polyoxotungstates nanoclusters by combining cerium linkers and SeO{sub 3}{sup 2-}/TeO{sub 3}{sup 2-} heteroanion templates: K{sub 32}Na{sub 16}[{(XO_3)W_1_0O_3_4}{sub 8}{Ce_8(H_2O)_2_0}(WO{sub 2}){sub 4}-(W{sub 4}O{sub 12})].n H{sub 2}O [X=Se, n=81 (1); X=Te, n=114 (2)] and K{sub 12}Na{sub 22}[{(SeO_3)W_1_0O_3_4}{sub 8}{Ce_8(H_2O)_2_0}(WO{sub 2}){sub 4}-{(W_4O_6)Ce_4(H_2O)_1_4(SeO_3)_4(NO_3)_2}] . 79 H{sub 2}O (3), which are the first lanthanide-containing polyoxotungstates with selenium or tellurium heteroatoms. The three clusters were characterized by single-crystal X-ray structure analysis, IR spectroscopy, thermogravimetric/differential thermal analysis, UV/Vis spectroscopy, ESI-MS, and X-ray photoelectron spectroscopy. Their electrochemical, photoluminescence, and magnetic properties were investigated. Their behavior in solution was studied by transmission electron microscopy, which showed that their single polyoxoanions assemble into intact, uniform-sized, purely inorganic hollow spheres in dilute water/acetone solution. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Temperature-dependent charge transport mechanisms in carbon sphere/polyaniline composite

    Science.gov (United States)

    Nieves, Cesar A.; Martinez, Luis M.; Meléndez, Anamaris; Ortiz, Margarita; Ramos, Idalia; Pinto, Nicholas J.; Zimbovskaya, Natalya

    2017-12-01

    Charge transport in the temperature range 80 K electrons between polymeric chains in PANi-filled gaps between CS is the predominant transport mechanism through CS/PANi composites. The high conductivity of the CS/PANi composite makes the material attractive for the fabrication of devices and sensors.

  8. Folic acid-functionalized magnetic ZnFe2O4 hollow microsphere core/mesoporous silica shell composite particles: synthesis and application in drug release.

    Science.gov (United States)

    Yang, Dandan; Wei, Kaiwei; Liu, Qi; Yang, Yong; Guo, Xue; Rong, Hongren; Cheng, Mei-Ling; Wang, Guoxiu

    2013-07-01

    A drug delivery system was designed by deliberately combining the useful functions into one entity, which was composed of magnetic ZnFe2O4 hollow microsphere as the core, and mesoporous silica with folic acid molecules as the outer shell. Amine groups coated magnetic ZnFe2O4 hollow microsphere core/mesoporous silica shell (MZHM-MSS-NH2) composite particles were first synthesized by a one-pot direct co-condensation method. Subsequently a novel kind of folic acid-functionalized magnetic ZnFe2O4 hollow microsphere core/mesoporous silica shell (MZHM-MSS-NHFA) composite particles were synthesized by conjugating folic acid as targeted molecule to MZHM-MSS-NH2. Ibuprofen, a well-known antiphlogistic drug, was used as a model drug to assess the loading and releasing behavior of the composite microspheres. The results show that the MZHM-MSS-NHFA system has the higher capacity of drug storage and good sustained drug-release property. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Interfacial Reaction Dependent Performance of Hollow Carbon Nanosphere – Sulfur Composite as a Cathode for Li-S Battery

    International Nuclear Information System (INIS)

    Zheng, Jianming; Yan, Pengfei; Gu, Meng; Wagner, Michael J.; Hays, Kevin A.; Chen, Junzheng; Li, Xiaohong; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie

    2015-01-01

    Lithium-sulfur (Li-S) battery is a promising energy storage system due to its high energy density, cost effectiveness, and environmental friendliness of sulfur. However, there are still a number of technical challenges, such as low Coulombic efficiency and poor long-term cycle life, impeding the commercialization of Li-S battery. The electrochemical performance of Li-S battery is closely related with the interfacial reactions occurring between hosting substrate and active sulfur species, which are poorly conducting at fully oxidized and reduced states. Here, we correlate the relationship between the performance and interfacial reactions in the Li-S battery system, using a hollow carbon nanosphere (HCNS) with highly graphitic character as hosting substrate for sulfur. With an appropriate amount of sulfur loading, HCNS/S composite exhibits excellent electrochemical performance because of the fast interfacial reactions between HCNS and the polysulfides. However, further increase of sulfur loading leads to increased formation of highly resistive insoluble reaction products (Li 2 S 2 /Li 2 S), which limits the reversibility of the interfacial reactions and results in poor electrochemical performances. These findings demonstrate the importance of the interfacial reaction reversibility in the whole electrode system on achieving high capacity and long cycle life of sulfur cathode for Li-S batteries.

  10. Interfacial Reaction Dependent Performance of Hollow Carbon Nanosphere – Sulfur Composite as a Cathode for Li-S Battery

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianming; Yan, Pengfei; Gu, Meng [Pacific Northwest National Laboratory, Richland, WA (United States); Wagner, Michael J.; Hays, Kevin A. [The George Washington University, Washington, DC (United States); Chen, Junzheng; Li, Xiaohong; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie, E-mail: jie.xiao@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States)

    2015-05-26

    Lithium-sulfur (Li-S) battery is a promising energy storage system due to its high energy density, cost effectiveness, and environmental friendliness of sulfur. However, there are still a number of technical challenges, such as low Coulombic efficiency and poor long-term cycle life, impeding the commercialization of Li-S battery. The electrochemical performance of Li-S battery is closely related with the interfacial reactions occurring between hosting substrate and active sulfur species, which are poorly conducting at fully oxidized and reduced states. Here, we correlate the relationship between the performance and interfacial reactions in the Li-S battery system, using a hollow carbon nanosphere (HCNS) with highly graphitic character as hosting substrate for sulfur. With an appropriate amount of sulfur loading, HCNS/S composite exhibits excellent electrochemical performance because of the fast interfacial reactions between HCNS and the polysulfides. However, further increase of sulfur loading leads to increased formation of highly resistive insoluble reaction products (Li{sub 2}S{sub 2}/Li{sub 2}S), which limits the reversibility of the interfacial reactions and results in poor electrochemical performances. These findings demonstrate the importance of the interfacial reaction reversibility in the whole electrode system on achieving high capacity and long cycle life of sulfur cathode for Li-S batteries.

  11. Facile synthesis and stable cycling ability of hollow submicron silicon oxide–carbon composite anode material for Li-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joong-Yeon; Nguyen, Dan Thien [Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kang, Joon-Sup [Department of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Song, Seung-Wan, E-mail: swsong@cnu.ac.kr [Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Department of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2015-06-05

    Highlights: • Hollow submicron SiO{sub 2}–carbon composite material was synthesized using Si{sup 4+}-citrate chelation. • Composite material possessed a homogeneous distribution of SiO{sub 2} and carbon. • Composite electrode delivered ⩾600 mAh/g with a stable cycling stability. • This materials design and synthesis provides a useful platform for scalable production. - Abstract: Advanced SiO{sub 2}–carbon composite anode active material for lithium-ion battery has been synthesized through a simple chelation of silicon cation with citrate in a glyme-based solvent. The resultant composite material demonstrates a homogeneous distribution of constituents over the submicron particles and a unique hollow spherical microstructure, which provides an enhanced electrical conductivity and better accommodation of volume change of silicon during electrochemical charge–discharge cycling, respectively. As a result, the composite electrode exhibits a high cycling stability delivering the capacity retention of 91% at the 100th cycle and discharge capacities of 662–602 mAh/g and coulombic efficiencies of 99.8%. This material synthesis is scalable and cost-effective in preparing various submicron or micron composite electrode materials.

  12. Optimization of strontium adsorption from aqueous solution using (mn-Zr) oxide-pan composite spheres

    International Nuclear Information System (INIS)

    Inan, S.; Altas, Y.

    2009-01-01

    The processes based on adsorption and ion exchange have a great role for the pre-concentration and separation of toxic, long lived radionuclides from liquid waste. In Nuclear waste management, the removal of long lived, radiotoxic isotopes from radioactive waste such as strontium reduces the storage problems and facilitates the disposal of the waste. Depending on the waste type, a variety of adsorbents and/or ion exchangers are used. Due to the amorphous structure of hydrous oxides and their mixtures, they don't have reproducible properties. Besides, obtained powders are very fine particles and they can cause operational problems such as pressure drop and filtration. Therefore they are not suitable for column applications. These reasons have recently expedited the study on the preparation of organic-inorganic composite adsorbent beads for industrial applications. PAN, as a stable and porous support for fine particles, provides the utilization of ion exchangers in large scale column applications. The utilization of PAN as a support material with many inorganic ion exchangers was firstly achieved by Sebesta in the beginning of 1990's. Later on, PAN based composite ion exchangers were prepared and used for the removal of radionuclides and heavy metal ions from aqueous solution and waste waters. In this study, spherical (Mn-Zr)oxide-PAN composite were prepared for separation of strontium from aqueous solution in a wide pH range. Sr 2 + adsorption of composite adsorbent was optimized by using experimental design 'Central Composite Design' model.

  13. HOLLOW FIBRE MEMBRANE

    NARCIS (Netherlands)

    Wessling, Matthias; Stamatialis, Dimitrios; Kopec, K.K.; Dutczak, S.M.

    2011-01-01

    The present invention relates to a process for manufacturing a hollow fibre membrane having a supporting layer and a separating layer, said process comprising: (a)extruding a spinning composition comprising a first polymer and a solvent for the first polymer through an inner annular orifice of a

  14. HOLLOW FIBRE MEMBRANE

    NARCIS (Netherlands)

    Wessling, Matthias; Stamatialis, Dimitrios; Kopec, K.K.; Dutczak, S.M.

    2013-01-01

    The present invention relates to a process for manufacturing a hollow fibre membrane having a supporting layer and a separating layer, said process comprising: (a) extruding a spinning composition comprising a first polymer and a solvent for the first polymer through an inner annular orifice of a

  15. Spray-Drying-Induced Assembly of Skeleton-Structured SnO2/Graphene Composite Spheres as Superior Anode Materials for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Liu, Dongdong; Kong, Zhen; Liu, Xuehua; Fu, Aiping; Wang, Yiqian; Guo, Yu-Guo; Guo, Peizhi; Li, Hongliang; Zhao, Xiu Song

    2018-01-24

    Three-dimensional skeleton-structured assemblies of graphene sheets decorated with SnO 2 nanocrystals are fabricated via a facile and large-scalable spray-drying-induced assembly process with commercial graphene oxide and SnO 2 sol as precursors. The influences of different parameters on the morphology, composition, structure, and electrochemical performances of the skeleton-structured SnO 2 /graphene composite spheres are studied by XRD, TGA, SEM, TEM, Raman spectroscopy, and N 2 adsorption-desorption techniques. Electrochemical properties of the composite spheres as the anode electrode for lithium-ion batteries are evaluated. After 120 cycles under a current density of 100 mA g -1 , the skeleton-structured SnO 2 /graphene spheres still display a specific discharge capacity of 1140 mAh g -1 . It is roughly 9.5 times larger than that of bare SnO 2 clusters. It could still retain a stable specific capacity of 775 mAh g -1 after 50 cycles under a high current density of 2000 mA g -1 , exhibiting extraordinary rate ability. The superconductivity of the graphene skeleton provides the pathway for electron transportation. The large pore volume deduced from the skeleton structure of the SnO 2 /graphene composite spheres increases the penetration of electrolyte and the diffusion of lithium ions and also significantly enhances the structural integrity by acting as a mechanical buffer.

  16. Facile synthesis of Co3O4 nanowires grown on hollow NiO microspheres with superior electrochemical performance

    International Nuclear Information System (INIS)

    Fan, Meiqing; Ren, Bo; Yu, Lei; Song, Dalei; Liu, Qi; Liu, Jingyuan; Wang, Jun; Jing, Xiaoyan; Liu, Lianhe

    2015-01-01

    Graphical abstract: Display Omitted - Highlights: • The NiO hollow spheres were decorated by Co 3 O 4 nanowires. • The NiO hollow spheres were comprised of many NiO particles. • The Co 3 O 4 nanowires were composed of nanoparticles. • The NiO/Co 3 O 4 core/shell nanocomposites have good electrochemical properties. - Abstract: The NiO/Co 3 O 4 core/shell composites as a promising supercapacitor material have been fabricated by facile hydrothermal process. The structure and morphology of the NiO/Co 3 O 4 core/shell composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that the NiO hollow spheres were decorated by Co 3 O 4 nanowires, and the nanowires were composed of nanoparticles. Electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The results suggested that the NiO/Co 3 O 4 core/shell composites had good electrochemical reversibility and displayed superior capacitive performance with large capacitance (510 F g −1 ). Moreover, NiO/Co 3 O 4 core/shell composites showed excellent cyclic performanceafter 1000 cycles

  17. Controlled Synthesis of Heterostructured SnO2-CuO Composite Hollow Microspheres as Efficient Cu-Based Catalysts for the Rochow Reaction

    Directory of Open Access Journals (Sweden)

    Hezhi Liu

    2018-04-01

    Full Text Available In this work, we report the design and synthesis of a series of heterostructured SnO2-CuO hollow microspherical catalysts (H-SnO2(x-CuO, x is the weight ratio of Sn/Cu for the Rochow reaction. The microspherical catalysts with nanosheets and nanoparticles as building blocks were prepared by a facile one-pot hydrothermal method coupled with calcination. When tested for the Rochow reaction, the prepared H-SnO2(0.2-CuO composite exhibited higher dimethyldichlorosilane selectivity (88.2% and Si conversion (36.7% than the solid CuO, hollow CuO and other H-SnO2(x-CuO microspherical samples, because in the former there is a stronger synergistic interaction between CuO and SnO2.

  18. Self-templated Synthesis of Nickel Silicate Hydroxide/Reduced Graphene Oxide Composite Hollow Microspheres as Highly Stable Supercapacitor Electrode Material.

    Science.gov (United States)

    Zhang, Yanhua; Zhou, Wenjie; Yu, Hong; Feng, Tong; Pu, Yong; Liu, Hongdong; Xiao, Wei; Tian, Liangliang

    2017-12-01

    Nickel silicate hydroxide/reduced graphene oxide (Ni 3 Si 2 O 5 (OH) 4 /RGO) composite hollow microspheres were one-pot hydrothermally synthesized by employing graphene oxide (GO)-wrapped SiO 2 microspheres as the template and silicon source, which were prepared through sonication-assisted interfacial self-assembly of tiny GO sheets on positively charged SiO 2 substrate microspheres. The composition, morphology, structure, and phase of Ni 3 Si 2 O 5 (OH) 4 /RGO microspheres as well as their electrochemical properties were carefully studied. It was found that Ni 3 Si 2 O 5 (OH) 4 /RGO microspheres featured distinct hierarchical porous morphology with hollow architecture and a large specific surface area as high as 67.6 m 2  g -1 . When utilized as a supercapacitor electrode material, Ni 3 Si 2 O 5 (OH) 4 /RGO hollow microspheres released a maximum specific capacitance of 178.9 F g -1 at the current density of 1 A g -1 , which was much higher than that of the contrastive bare Ni 3 Si 2 O 5 (OH) 4 hollow microspheres and bare RGO material developed in this work, displaying enhanced supercapacitive behavior. Impressively, the Ni 3 Si 2 O 5 (OH) 4 /RGO microsphere electrode exhibited outstanding rate capability and long-term cycling stability and durability with 97.6% retention of the initial capacitance after continuous charging/discharging for up to 5000 cycles at the current density of 6 A g -1 , which is superior or comparable to that of most of other reported nickel-based electrode materials, hence showing promising application potential in the energy storage area.

  19. Synthesis and electrochemical properties of porous double-shelled Mn2O3 hollow microspheres as a superior anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Qiao, Yu; Yu, Yan; Jin, Yi; Guan, Yi-Biao; Chen, Chun-Hua

    2014-01-01

    Highlights: • Double-shelled Mn 2 O 3 hollow microspheres are prepared by a multi-step. • synthesis procedure. • Solid, hollow and yolk-structured Mn 2 O 3 spheres are prepared for comparison. • The double-shelled hollow Mn 2 O 3 is superior in electrochemical properties. - Abstract: By means of a specially designed multi-step synthesis procedure involving steps of precipitation, controlled oxidation, selective etching and calcination, porous double-shelled Mn 2 O 3 hollow microspheres are synthesized. Solid, hollow and yolk-structured Mn 2 O 3 are also similarly synthesized for comparison. X-ray diffraction, scanning and transmission electron microscopies, IR spectroscopy, thermogravimetry, and Brunauer-Emmett-Teller measurements are employed to investigate their structures and compositions. Galvanostatic cell cycling and impedance spectroscopy are used to characterize the electrochemical properties of Mn 2 O 3 /Li cells. The results show that the hierarchical hollow structured (double-shelled, hollow and yolk-structured) Mn 2 O 3 anode materials deliver higher reversible capacities and excellent cycling stabilities than the solid Mn 2 O 3 . Moreover, among the three hierarchical hollow structured samples, the double shelled sample possesses the best cycling performance, especially at a high current density

  20. A Review on Preparation Techniques of TiO2 Hollow Spheres and Their Applications in Dye-sensitized Solar Cell and Lithium Ion Battery%TiO2空心球制备及在染料敏化太阳能电池和锂离子电池中应用的研究进展∗

    Institute of Scientific and Technical Information of China (English)

    刘作花; 许秀玲; 周国伟

    2016-01-01

    空心球结构的半导体氧化物具有密度低、比表面积大、机械和热稳定性好等优点。空心球结构对 TiO2纳米材料的电化学性能有着显著的优化作用,TiO2空心球作为一种重要的半导体氧化物具有良好的物理和化学性质,在多种领域均表现出潜在的应用价值,制备大小和壳层数均可控的半导体TiO2空心球已引起了研究者的广泛关注。主要综述了在硬模板、软模板和无模板条件下TiO2空心球的制备方法;同时还介绍了其在染料敏化太阳能电池和锂离子电池方面的最新研究进展;最后,对TiO2空心球的可控合成前景进行了展望。%Semiconductor oxide materials with hollow spherical structures have attracted enormous attention due to their low density,large specific area,mechanical and thermal stability.As one of the important semiconductor oxide materials,TiO2 hollow spheres have excellent electrochemical properties.Owing to the excellent physical and chemical properties for potential application in multiple fields,design and synthesis of semiconductor TiO2 with tuna-ble size,shells and interior architecture have attracted great research interest.In this paper,the synthesis of TiO2 hol-low spheres in different methods,such as hard template,soft template and template-free methods are summarized. The progress of the applications of these materials in dye-sensitized solar cell and lithium ion battery are also dis-cussed.Finally,the future development of the controllable fabrication of TiO2 hollow spheres is looked forward.

  1. Robust outer-selective thin-film composite polyethersulfone hollow fiber membranes with low reverse salt flux for renewable salinity-gradient energy generation

    KAUST Repository

    Cheng, Zhen Lei; Li, Xue; Liu, Ying Da; Chung, Neal Tai-Shung

    2016-01-01

    This study reports outer-selective thin-film composite (TFC) hollow fiber membranes with extremely low reverse salt fluxes and robustness for harvesting salinity-gradient energy from pressure retarded osmosis (PRO) processes. Almost defect-free polyamide layers with impressive low salt permeabilities were synthesized on top of robust polyethersulfone porous supports. The newly developed TFC-II membrane shows a maximum power density of 7.81 W m−2 using 1 M NaCl and DI water as feeds at 20 bar. Reproducible data obtained in the 2nd and 3rd runs confirm its stability under high hydraulic pressure differences. Comparing to other PRO membranes reported in the literature, the newly developed membrane exhibits not only the smallest slope between water flux decline and ΔPΔP increase but also the lowest ratio of reverse salt flux to water flux. Thus, the effective osmotic driving force could be well maintained even under high pressure operations. For the first time, the effect of feed pressure buildup induced by feed flowrate was evaluated towards PRO performance. A slight increment in feed pressure buildup was found to be beneficial to water flux and power density up to 10.06 W m−2 without comprising the reverse salt flux. We believe this study may open up new perspectives on outer-selective PRO hollow fiber membranes and provide useful insights to understand and design next-generation outer-selective TFC hollow fiber membranes for osmotic power generation.

  2. Robust outer-selective thin-film composite polyethersulfone hollow fiber membranes with low reverse salt flux for renewable salinity-gradient energy generation

    KAUST Repository

    Cheng, Zhen Lei

    2016-01-08

    This study reports outer-selective thin-film composite (TFC) hollow fiber membranes with extremely low reverse salt fluxes and robustness for harvesting salinity-gradient energy from pressure retarded osmosis (PRO) processes. Almost defect-free polyamide layers with impressive low salt permeabilities were synthesized on top of robust polyethersulfone porous supports. The newly developed TFC-II membrane shows a maximum power density of 7.81 W m−2 using 1 M NaCl and DI water as feeds at 20 bar. Reproducible data obtained in the 2nd and 3rd runs confirm its stability under high hydraulic pressure differences. Comparing to other PRO membranes reported in the literature, the newly developed membrane exhibits not only the smallest slope between water flux decline and ΔPΔP increase but also the lowest ratio of reverse salt flux to water flux. Thus, the effective osmotic driving force could be well maintained even under high pressure operations. For the first time, the effect of feed pressure buildup induced by feed flowrate was evaluated towards PRO performance. A slight increment in feed pressure buildup was found to be beneficial to water flux and power density up to 10.06 W m−2 without comprising the reverse salt flux. We believe this study may open up new perspectives on outer-selective PRO hollow fiber membranes and provide useful insights to understand and design next-generation outer-selective TFC hollow fiber membranes for osmotic power generation.

  3. Enhanced NO2 sensing characteristics of Au modified porous silicon/thorn-sphere-like tungsten oxide composites

    Science.gov (United States)

    Yuan, Lin; Hu, Ming; Wei, Yulong; Ma, Wenfeng

    2016-12-01

    The thorn-sphere-like tungsten oxide (WO3) made up by 1D nanorods has been successfully synthesized through hydrothermal method on the Au-modified porous silicon (PS) substrates with seed-layer induction. By using XRD, EDS, FESEM and TEM techniques, we tested and verified that the crystal structure and morphology evolution of WO3 hierarchical nanostructure on the Au-modified PS strongly depend on the Au-sputtering time and hydrothermal reaction time. In addition, by comparing the NO2-sensing properties of the prepared products, we found that the 10 s-Au decorated PS/WO3-3 h (sputtering Au for 10 s and hydrothermal reaction for 3 h) composites sensor behaving as a typical p-type semiconductor and operating at room temperature (RT) exhibits high sensitivity and response characteristics even to ppb-level NO2, which makes this kind of sensor a competitive candidate for NO2-sensing applications. Moreover, the enhanced response may not only due to the high specific surface area but the Au nanoparticles acting as promoters for the spillover effect and forming metal-semiconductor heterojunctions with the PS and WO3. The transmission of electrons and holes in the heterogeneous interface generated among PS, WO3 and Au is proposed to illustrate the p-type response mechanism.

  4. Synthesis, morphological control, and antibacterial properties of hollow/solid Ag2S/Ag heterodimers

    KAUST Repository

    Pang, Maolin

    2010-08-11

    Ag2S and Ag are important functional materials that have received considerable research interest in recent years. In this work, we develop a solution-based synthetic method to combine these two materials into hollow/solid Ag2S/Ag heterodimers at room temperature. Starting from monodisperse Cu2O solid spheres, CuS hollow spheres can be converted from Cu2O through a modified Kirkendall process, and the obtained CuS can then be used as a solid precursor for preparation of the Ag2S/Ag heterodimers through ion exchange and photo-assisted reduction. We have found that formation of the Ag2S/Ag heterodimers is instantaneous, and the size of Ag nanocrystals on the hollow spheres of Ag2S can be controlled by changing the concentration and power of reducing agents in the synthesis. The growth of Ag nanoparticles on hollow spheres of Ag2S in the dimers is along the [111] direction of the silver crystal; the light absorption properties have also been investigated. Furthermore, coupling or tripling of Ag2S/Ag heterodimers into dumbbell-like trimers ((Ag 2S)2/Ag, linear) and triangular tetramers ((Ag 2S)3/Ag, coplanar) can also be attained at 60°C by adding the bidentate ligand ethylenediamine as a cross-linking agent. To test the applicability of this highly asymmetric dipolar composite, photocatalytic inactivation of Escherichia coli K-12 in the presence of the as-prepared Ag 2S/Ag heterodimers has been carried out under UV irradiation. The added Ag2S/Ag heterodimers show good chemical stability under prolonged UV irradiation, and no appreciable solid dissolution is found. Possible mechanisms regarding the enhanced antibacterial activity have also been addressed. © 2010 American Chemical Society.

  5. The photocatalytic properties of hollow (GaN){sub 1-x}(ZnO){sub x} composite nanofibers synthesized by electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ding; Zhang, Minglu; Zhuang, Huaijuan; Chen, Xu [College of Materials Science and Engineering, University of Shanghai for Science & Technology, Shanghai, 200093 (China); Wang, Xianying, E-mail: Xianyingwang@usst.edu.cn [College of Materials Science and Engineering, University of Shanghai for Science & Technology, Shanghai, 200093 (China); Zheng, Xuejun, E-mail: zhengxuejun@xtu.edu.cn [School of Mechanical Engineering, Xiangtan University, Xiangtan, 411105 (China); Key Laboratory of Welding Robot and Application Technology of Hunan Province, Xiangtan University, Xiangtan, 411105 (China); Yang, Junhe [College of Materials Science and Engineering, University of Shanghai for Science & Technology, Shanghai, 200093 (China)

    2017-02-28

    Highlights: • (GaN){sub 1-x}(ZnO){sub x} composite nanofibers were obtained by electrospinning method. • Phase transition from ZnGa{sub 2}O{sub 4} to (GaN){sub 1-x}(ZnO){sub x} under NH{sub 3} was observed. • Hollow and porous structure was confirmed by SEM and TEM investigation. • GaN:ZnO with optimal ratio of 1:2 displayed highest photocatalytic activity. - Abstract: (GaN){sub 1-x}(ZnO){sub x} composite nanofibers with hollow structure were prepared by initial electrospinning, and the subsequent calcination and nitridation. The structure and morphology characteristics of samples were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The characterization results showed the phase transition from ZnGa{sub 2}O{sub 4} to (GaN){sub 1-x}(ZnO){sub x} solid-solution under ammonia atmosphere. The preparation conditions were explored and the optimum nitridation temperature and holding time are 750 °C and 2 h, respectively. The photocatalytic properties of (GaN){sub 1-x}(ZnO){sub x} with different Ga:Zn atomic ratios were investigated by degrading Rhodamine B under the visible light irradiation. The photocatalytic activity sequence is (GaN){sub 1−x}(ZnO){sub x} (Ga:Zn = 1:2) > (GaN){sub 1−x}(ZnO){sub x} (Ga:Zn = 1:3) > ZnO nanofibers > (GaN){sub 1−x}(ZnO){sub x} (Ga:Zn = 1:4) > (GaN){sub 1−x}(ZnO){sub x} (Ga:Zn = 1:1). The photocatalytic mechanism of the (GaN){sub 1−x}(ZnO){sub x} hollow nanofibers was further studied by UV–vis diffuse reflectance spectra. The excellent photocatalytic performance of (GaN){sub 1−x}(ZnO){sub x} hollow nanofibers was attributed to the narrow band gap and high surface area of porous nanofibers with hollow structure.

  6. Ag/α-Fe{sub 2}O{sub 3} hollow microspheres: Preparation and application for hydrogen peroxide detection

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Xinyuan; Wu, Zhiping; Liao, Fang, E-mail: liaozhang2003@163.com; Zhang, Tingting; Guo, Tingting

    2015-09-15

    In this paper, we demonstrated a simple approach for preparing α-Fe{sub 2}O{sub 3} hollow spheres by mixing ferric nitrate aqueous and glucose in 180 °C. The glucose was found to act as a soft template in the process of α-Fe{sub 2}O{sub 3} hollow spheres formation. Ag/α-Fe{sub 2}O{sub 3} hollow nanocomposite was obtained under UV irradiation without additional reducing agents or initiators. Synthesized Ag/α-Fe{sub 2}O{sub 3} hollow composites exhibited remarkable catalytic performance toward H{sub 2}O{sub 2} reduction. The electrocatalytic activity mechanism of Ag/α-Fe{sub 2}O{sub 3}/GCE were discussed toward the reduction of H{sub 2}O{sub 2} in this paper. - Graphical abstract: Glucose is carbonized as carbon balls in the 180 °C hydrothermal carbonization process, which plays a role of a soft template. Carbon spherical shell is rich in many hydroxyls, which have good hydrophilicity and surface reactivity. When Fe(NO{sub 3}){sub 3} is added to the aqueous solution of Glucose, the hydrophilic -OH will adsorb Fe{sup 3+} to form coordination compound by coordination bond. α-FeOOH is formed on the surface of carbon balls by hydrothermal reaction. After calcination at 500 °C, carbon spheres react with oxygen to form carbon dioxide, which disappears in the air. Meanwhile α-FeOOH is calcined to form α-Fe{sub 2}O{sub 3} hollow spheres.

  7. Transient thermal stresses in a transversely isotropic finite composite hollow circular cylinder due to arbitrary surface heat-generations and surrounding temperatures

    International Nuclear Information System (INIS)

    Sugano, Y.

    1981-01-01

    An exact solution is given for the temperature distribution, the thermal stresses and displacements in a transversely isotropic finite composite hollow circular cylinder composed of two distinct cylindrical laminae. The temperature field is determined by using of the Laplace transform and the finite Fourier-cosine transform, respectively, with respect to time and axial coordinate included in the governing equation and the associated thermal stresses and displacements are analvsed by the use of a set of stress functions closely related to the Love's function valid for the axisymmetric isothermal problem of isotropic bodies. (orig.)

  8. Carbon-covered Fe{sub 3}O{sub 4} hollow cubic hierarchical porous composite as the anode material for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shouhui, E-mail: csh2k@jxnu.edu.cn; Zhou, Rihui; Chen, Yaqin; Fu, Yuanyuan; Li, Ping; Song, Yonghai; Wang, Li, E-mail: lwanggroup@aliyun.com [Jiangxi Normal University, College of Chemistry and Chemical Engineering (China)

    2017-04-15

    In this work, Prussian blue nanocrystals, a kind of cubic metal-organic frameworks, was firstly covered by a uniform layer of resorcinol-formaldehyde (RF) resin, and then followed with heat treatment at different pyrolysis temperatures. The effects of pyrolysis temperature on the morphologies, phase, pore size, and electrochemical performance of the pyrolysis products were studied in this work. The composite generated at 600 {sup ∘}C, FexC600, was a hollow cubic composite of Fe{sub 3}O{sub 4} covered by a thin RF-derived carbon layer. The carbon layer on FexC600 was a robust and conductive protective layer, which can accommodate Fe{sub 3}O{sub 4} NPs and withstand the huge volume change of Fe{sub 3}O{sub 4} during the process of discharge and charge. When used as anodes for lithium-ion batteries, FexC600 showed excellent electrochemical performance. It delivered a discharge capacity of 1126 mAh g{sup −1} with a coulombic efficiency of 98.8% at the current density of 100 mA g{sup −1} after 100 times discharge/charge cycling. It even delivered a capacity of 492 mAh g{sup −1} at the current density of 500 mA g{sup −1}. This cubic hollow composite would be a promising alternative anode material for lithium-ion batteries.

  9. Carbon-covered Fe_3O_4 hollow cubic hierarchical porous composite as the anode material for lithium-ion batteries

    International Nuclear Information System (INIS)

    Chen, Shouhui; Zhou, Rihui; Chen, Yaqin; Fu, Yuanyuan; Li, Ping; Song, Yonghai; Wang, Li

    2017-01-01

    In this work, Prussian blue nanocrystals, a kind of cubic metal-organic frameworks, was firstly covered by a uniform layer of resorcinol-formaldehyde (RF) resin, and then followed with heat treatment at different pyrolysis temperatures. The effects of pyrolysis temperature on the morphologies, phase, pore size, and electrochemical performance of the pyrolysis products were studied in this work. The composite generated at 600 "∘C, FexC600, was a hollow cubic composite of Fe_3O_4 covered by a thin RF-derived carbon layer. The carbon layer on FexC600 was a robust and conductive protective layer, which can accommodate Fe_3O_4 NPs and withstand the huge volume change of Fe_3O_4 during the process of discharge and charge. When used as anodes for lithium-ion batteries, FexC600 showed excellent electrochemical performance. It delivered a discharge capacity of 1126 mAh g"−"1 with a coulombic efficiency of 98.8% at the current density of 100 mA g"−"1 after 100 times discharge/charge cycling. It even delivered a capacity of 492 mAh g"−"1 at the current density of 500 mA g"−"1. This cubic hollow composite would be a promising alternative anode material for lithium-ion batteries.

  10. Facile synthesis of one-dimensional hollow Sb2O3@TiO2 composites as anode materials for lithium ion batteries

    Science.gov (United States)

    Wang, Zhaomin; Cheng, Yong; Li, Qian; Chang, Limin; Wang, Limin

    2018-06-01

    Metallic Sb is deemed as a promising anode material for lithium ion batteries (LIBs) due to its flat voltage platform and high security. Nevertheless, the limited capacity restricts its large-scale application. Therefore, a simple and effective method to explore novel antimony trioxide with high capacity used as anode material for LIBs is imperative. In this work, we report a facile and efficient strategy to fabricate 1D hollow Sb2O3@TiO2 composites by using the Kirkendall effect. When used as an anode material for LIBs, the optimal Sb2O3@TiO2 composite displays a high reversible discharge capacity of 593 mAh g-1 at a current density of 100 mA g-1 after 100 cycles and a relatively superior discharge capacity of 439 mAh g-1 at a current density of 500 mA g-1 even after 600 cycles. In addition, a reversible discharge capacity of 334 mAh g-1 can also be obtained even at a current density of 2000 mA g-1. The excellent cycling stability and rate performance of the Sb2O3@TiO2 composite can be attributed to the synergistic effect of TiO2 shell and hollow structure of Sb2O3, both of which can effectively buffer the volume expansion and maintain the integrity of the electrode during the repeated charge-discharge cycles.

  11. Computational study of fluid flow and heat transfer in composite packed beds of spheres with low tube to particle diameter ratio

    International Nuclear Information System (INIS)

    Yang, Jian; Wu, Jiangquan; Zhou, Lang; Wang, Qiuwang

    2016-01-01

    Highlights: • Flow and heat transfer in composite packed beds with low d_t/d_p_e are investigated. • The wall effect would be restrained with radially layered composite packing (RLM). • Heat flux and overall heat transfer efficiency can be improved with RLM packing. - Abstract: The effect of the tube wall on the fluid flow and heat transfer would be important in the packed bed with low tube to particle diameter ratio, which may lead to flow and temperature maldistributions inside, and the heat transfer performance may be lowered. In the present paper, the flow and heat transfer performances in both the composite and uniform packed beds of spheres with low tube to particle diameter were numerically investigated, where the composite packing means randomly packing with non-uniform spheres and the uniform packing means randomly packing with uniform spheres, including radially layered composite packing (RLM), axially layered composite packing (ALM), randomly composite packing (RCM) and randomly uniform packing (RPM). Both the composite and uniform packings were generated with discrete element method (DEM), and the influence of the wall effect on the flow and heat transfer in the packed beds were carefully studied and compared with each other. Firstly, it is found that, the wall effect on the velocity and temperature distributions in the randomly packed bed of uniform spheres (RPM) with low tube to particle diameter ratio were obvious. The average velocity of the near-tube-wall region is higher than that of the inner-tube region in the bed. When the tube wall is adiabatic, the average temperature of the near-tube-wall region is lower. With radially layered composite packing method (RLM), smaller pores would be formed close to the tube wall and big flow channels would be formed in the inner-tube region of the bed, which would be benefit to restrain the wall effect and improve heat transfer in the bed with low tube to particle diameter ratio. Furthermore, it is also

  12. Computational study of fluid flow and heat transfer in composite packed beds of spheres with low tube to particle diameter ratio

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jian, E-mail: yangjian81@mail.xjtu.edu.cn [Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China); Wu, Jiangquan [CSR Research of Electrical Technology and Material Engineering, Zhuzhou, Hunan 412001 (China); Zhou, Lang; Wang, Qiuwang [Key Laboratory of Thermo-Fluid Science and Engineering, Ministry of Education, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049 (China)

    2016-04-15

    Highlights: • Flow and heat transfer in composite packed beds with low d{sub t}/d{sub pe} are investigated. • The wall effect would be restrained with radially layered composite packing (RLM). • Heat flux and overall heat transfer efficiency can be improved with RLM packing. - Abstract: The effect of the tube wall on the fluid flow and heat transfer would be important in the packed bed with low tube to particle diameter ratio, which may lead to flow and temperature maldistributions inside, and the heat transfer performance may be lowered. In the present paper, the flow and heat transfer performances in both the composite and uniform packed beds of spheres with low tube to particle diameter were numerically investigated, where the composite packing means randomly packing with non-uniform spheres and the uniform packing means randomly packing with uniform spheres, including radially layered composite packing (RLM), axially layered composite packing (ALM), randomly composite packing (RCM) and randomly uniform packing (RPM). Both the composite and uniform packings were generated with discrete element method (DEM), and the influence of the wall effect on the flow and heat transfer in the packed beds were carefully studied and compared with each other. Firstly, it is found that, the wall effect on the velocity and temperature distributions in the randomly packed bed of uniform spheres (RPM) with low tube to particle diameter ratio were obvious. The average velocity of the near-tube-wall region is higher than that of the inner-tube region in the bed. When the tube wall is adiabatic, the average temperature of the near-tube-wall region is lower. With radially layered composite packing method (RLM), smaller pores would be formed close to the tube wall and big flow channels would be formed in the inner-tube region of the bed, which would be benefit to restrain the wall effect and improve heat transfer in the bed with low tube to particle diameter ratio. Furthermore, it

  13. Preparation of flower-like TiO{sub 2} sphere/reduced graphene oxide composites for photocatalytic degradation of organic pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Woong [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of); Park, Mira [Department of Organic Materials and Fiber Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Kim, Hak Yong [Department of BIN Convergence technology, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Incheon 402-751 (Korea, Republic of)

    2016-07-15

    In this study, novel flower-like TiO{sub 2} sphere (FTS)/reduced graphene oxide (rGO) composites (FTS-G) were synthesized via a hydrothermal method. The photocatalytic performance of the FTS-G composites was evaluated through the photodegradation of rhodamine B (Rh B) and trichloroethylene (TCE) under simulated solar light irradiation. The rGO to FTS ratio in the composites significantly affected photocatalytic activity. The photocatalytic activities of FTS-Gs in the degradation of Rh B and TCE were superior to that of pure FTS. Of all the FTS-G composites tested, FTS-G with 1 wt% rGO (FTS-G-1) had the greatest photocatalytic activity, while FTS-G composites with rGO contents over 1 wt% had lower photocatalytic activities. Additionally, it is expected that the synthesis of FTS with a high specific surface area and well-developed pore structure and simultaneous conversion of GO to graphene-like rGO without the use of strong reducing agents could be a promising strategy to prepare other carbon-based flower-like TiO{sub 2} sphere composite photocatalysts. - Graphical abstract: Schematic illustration of high photocatalytic activity for FTS-G composites. Display Omitted.

  14. Enhanced thermal properties of novel shape-stabilized PEG composite phase change materials with radial mesoporous silica sphere for thermal energy storage

    OpenAIRE

    Min, Xin; Fang, Minghao; Huang, Zhaohui; Liu, Yan?gai; Huang, Yaoting; Wen, Ruilong; Qian, Tingting; Wu, Xiaowen

    2015-01-01

    Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that...

  15. Injectable biocompatible and biodegradable pH-responsive hollow particle gels containing poly(acrylic acid): the effect of copolymer composition on gel properties.

    Science.gov (United States)

    Halacheva, Silvia S; Adlam, Daman J; Hendow, Eseelle K; Freemont, Tony J; Hoyland, Judith; Saunders, Brian R

    2014-05-12

    The potential of various pH-responsive alkyl (meth)acrylate ester- and (meth)acrylic acid-based copolymers, including poly(methyl methacrylate-co-acrylic acid) (PMMA-AA) and poly(n-butyl acrylate-co-methacrylic acid) (PBA-MAA), to form pH-sensitive biocompatible and biodegradable hollow particle gel scaffolds for use in non-load-bearing soft tissue regeneration have been explored. The optimal copolymer design criteria for preparation of these materials have been established. Physical gels which are both pH- and redox-sensitive were formed only from PMMA-AA copolymers. MMA is the optimal hydrophobic monomer, whereas the use of various COOH-containing monomers, e.g., MAA and AA, will always induce a pH-triggered physical gelation. The PMMA-AA gels were prepared at physiological pH range from concentrated dispersions of swollen, hollow, polymer-based particles cross-linked with either cystamine (CYS) or 3,3'-dithiodipropionic acid dihydrazide (DTP). A linear relationship between particle swelling ratios, gel elasticity, and ductility was observed. The PMMA-AA gels with lower AA contents feature lower swelling ratios, mechanical strengths, and ductilities. Increasing the swelling ratio (e.g., through increasing AA content) decreased the intraparticle elasticity; however, intershell contact and gel elasticity were found to increase. The mechanical properties and performance of the gels were tuneable upon varying the copolymers' compositions and the structure of the cross-linker. Compared to PMMA-AA/CYS, the PMMA-AA/DTP gels were more elastic and ductile. The biodegradability and cytotoxicity of the new hollow particle gels were tested for the first time and related to their composition, mechanical properties, and morphology. The new PMMA-AA/CYS and PMMA-AA/DTP gels have shown good biocompatibility, biodegradability, strength, and interconnected porosity and therefore have good potential as a tissue repair agent.

  16. Geometrical Dynamics in a Transitioning Superconducting Sphere

    Directory of Open Access Journals (Sweden)

    Claycomb J. R.

    2006-10-01

    Full Text Available Recent theoretical works have concentrated on calculating the Casimir effect in curved spacetime. In this paper we outline the forward problem of metrical variation due to the Casimir effect for spherical geometries. We consider a scalar quantum field inside a hollow superconducting sphere. Metric equations are developed describing the evolution of the scalar curvature after the sphere transitions to the normal state.

  17. Core-shell composite of hierarchical MoS2 nanosheets supported on graphitized hollow carbon microspheres for high performance lithium-ion batteries

    International Nuclear Information System (INIS)

    Xia, Yuan; Wang, Beibei; Zhao, Xiaojun; Wang, Gang; Wang, Hui

    2016-01-01

    In this work, a core-shell composite composed of MoS 2 nanosheets grown on hollow carbon microspheres is synthesized by a hydrothermal and a subsequent annealing route. The result shows that well-graphitized hollow-carbon@highlycrystallineMoS 2 (HC@MoS 2 ) was obtained after the four-step reaction. And it is found that the synthesized MoS 2 is consist of 2H and 1T phases. The lithium storage property of the composite is investigated as an anode material for lithium-ion batteries. Benefited from the special morphology and structure, a stable capacity of 970 mAh g −1 for over 100 cycles at a current density of 0.25 A g −1 is realized on the material. Even at a high current density of 4 A g −1 , a reversible capacity as high as 560 mAh g −1 is delivered. Moreover, the reasons for the excellent electrochemical performance of the material are explored and discussed in detail.

  18. Fabrication of novel micro-nano carbonous composites based on self-made hollow activated carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Kong Yuxia; Qiu Tingting [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Qiu Jun, E-mail: qiujun@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Key Laboratory of Advanced Civil Engineering Materials of Education of Ministry, Shanghai 201804 (China)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Hollow pipe and porous HACF with solid carbon net framework structure were successfully prepared by template method. Black-Right-Pointing-Pointer CNTs were grown successfully on the self-made HACF substrate by CVD techniques. Black-Right-Pointing-Pointer A novel tree-like micro-nano carbonous structure CNTs/HACF was fabricated. Black-Right-Pointing-Pointer The formation mechanism of micro phase HACF and nano phase CNTs were respectively discussed. - Abstract: The hollow activated carbon fibers (HACF) were prepared by using commercial polypropylene hollow fiber (PPHF) as the template, and phenol-formaldehyde resin (PF) as carbon precursors. Final HACF was formed through the thermal decomposition and carbonization of PF at 700 Degree-Sign C under the nitrogen atmosphere, and activation at 800 Degree-Sign C with carbon dioxide as the activating agent, consecutively. Then, carbon nanotubes (CNTs) were grown by chemical vapor deposition (CVD) techniques using the as-grown porous HACF as substrate. The growth process was achieved by pyrolyzing ethanol steam at 700 Degree-Sign C using nickel as catalyst. Finally, CNTs was grown successfully on the substrate, and a novel tree-like micro-nano carbonous structure CNTs/HACF was fabricated. The as-grown HACF and micro-nano CNTs/HACF were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG), respectively. Moreover, the formation mechanisms were also discussed.

  19. Enhanced thermal properties of novel shape-stabilized PEG composite phase change materials with radial mesoporous silica sphere for thermal energy storage.

    Science.gov (United States)

    Min, Xin; Fang, Minghao; Huang, Zhaohui; Liu, Yan'gai; Huang, Yaoting; Wen, Ruilong; Qian, Tingting; Wu, Xiaowen

    2015-08-11

    Radial mesoporous silica (RMS) sphere was tailor-made for further applications in producing shape-stabilized composite phase change materials (ss-CPCMs) through a facile self-assembly process using CTAB as the main template and TEOS as SiO2 precursor. Novel ss-CPCMs composed of polyethylene glycol (PEG) and RMS were prepared through vacuum impregnating method. Various techniques were employed to characterize the structural and thermal properties of the ss-CPCMs. The DSC results indicated that the PEG/RMS ss-CPCM was a promising candidate for building thermal energy storage applications due to its large latent heat, suitable phase change temperature, good thermal reliability, as well as the excellent chemical compatibility and thermal stability. Importantly, the possible formation mechanisms of both RMS sphere and PEG/RMS composite have also been proposed. The results also indicated that the properties of the PEG/RMS ss-CPCMs are influenced by the adsorption limitation of the PEG molecule from RMS sphere with mesoporous structure and the effect of RMS, as the impurities, on the perfect crystallization of PEG.

  20. Soft-template-synthesis of hollow CuO/Co{sub 3}O{sub 4} composites for pseudo-capacitive electrode: A synergetic effect on electrochemical performance

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kuaibing, E-mail: wangkb@njau.edu.cn [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093 (China); Lv, Bo; Wu, Hua; Luo, Xuefei; Xu, Jiangyan [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Geng, Zhirong [State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093 (China)

    2016-12-15

    Hollow CuO/Co{sub 3}O{sub 4} hybrids, which inherited from its coordination polymer precursor consisting of sheets layer and nanoparticles layer composites, were synthesized and characterized by SEM, EDX, XRD and XPS. To assess its electrochemical capacitive performances, cyclic voltammetry, galvanostatic charging-discharging measurements and A.C. impedance tests were performed successively. The CuO/Co{sub 3}O{sub 4} hybrids had higher capacitance and lower charge transfer resistance than bare Co{sub 3}O{sub 4} nanostructures, revealing that it provided a protection layer and produced a synergistic effect due to the existence of CuO layer. The distinct synergistic effect could be further confirmed by endurance cycling tests. The capacitance of the CuO/Co{sub 3}O{sub 4} hybrids was 111% retained after 500 cycles at a charging rate of 1.0 A g{sup −1} and remained an intense growth trend after 2000 cycles at scan rate of 200 mV s{sup −1}. - Graphical abstract: Hollow CuO/Co{sub 3}O{sub 4} hybrids are synthesized and display a peculiar synergetic effect on the resulting performances, which can further be evaluated and confirmed by series of electrochemical measurements. - Highlights: • Hollow CuO/Co{sub 3}O{sub 4} hybrids are synthesized from bimetallic-Schiff base polymer precursors. • The capacitance of the CuO/Co{sub 3}O{sub 4} hybrids keeps a growth tendency after 2000 cycles. • A synergetic effect is found for the hybrids in electrochemical energy storage process.

  1. Problems in the Identification of Application Areas of Hollow Spheres and Hollow Sphere Structures

    Science.gov (United States)

    Augustin, Christian

    Victor Hugo (1802-1865) is attributed the verifiably false quotation that nothing is as powerful as an idea, whose time has come. Be that as it may, this quotation is at first a causality statement, which combines the presence of a certain idea in connection with specific basic conditions (time) as almost inevitable for a certain successful development. At first thought this linkage, that if an idea finds its perfect timing it will be successful, seems to be evident. By “time” we not only mean the chronological period, but as an abstract category of environmental conditions that occur at this time at a specific place.

  2. Public Sphere

    DEFF Research Database (Denmark)

    Trenz, Hans-Jörg

    2015-01-01

    In modern societies, the public sphere represents the intermediary realm that supports the communication of opinions, the discovery of problems that need to be dealt with collectively, the channeling of these problems through the filter of the media and political institutions, and the realization...... of the collective will of the people in the act of democratic self-government. The concept of the public sphere is used across the fields of media and communication research, cultural studies and the humanities, the history of ideas, legal and constitutional studies as well as democracy studies. Historically......, public spheres have undergone structural transformations that were closely connected to the emergence of different mass media. More recently, they are subject to trends of transnationalization and digitalization in politics and society....

  3. The thermal conductivity of beds of spheres

    International Nuclear Information System (INIS)

    McElroy, D.L.; Weaver, F.J.; Shapiro, M.; Longest, A.W.; Yarbrough, D.W.

    1987-01-01

    The thermal conductivities (k) of beds of solid and hollow microspheres were measured using two radial heat flow techniques. One technique provided k-data at 300 K for beds with the void spaces between particles filled with argon, nitrogen, or helium from 5 kPa to 30 MPa. The other technique provided k-data with air at atmospheric pressure from 300 to 1000 K. The 300 K technique was used to study bed systems with high k-values that can be varied by changing the gas type and gas pressure. Such systems can be used to control the operating temperature of an irradiation capsule. The systems studied included beds of 500 μm dia solid Al 2 O 3 , the same Al 2 O 3 spheres mixed with spheres of silica--alumina or with SiC shards, carbon spheres, and nickel spheres. Both techniques were used to determine the k-value of beds of hollow spheres with solid shells of Al 2 O 3 , Al 2 O 3 /center dot/7 w/o Cr 2 O 3 , and partially stabilized ZrO 2 . The hollow microspheres had diameters from 2100 to 3500 μm and wall thicknesses from 80 to 160 μm. 12 refs., 7 figs., 4 tabs

  4. Embedding of Hollow Polymer Microspheres with Hydrophilic Shell in Nafion Matrix as Proton and Water Micro-Reservoir

    Directory of Open Access Journals (Sweden)

    Zhaolin Liu

    2012-08-01

    Full Text Available Assimilating hydrophilic hollow polymer spheres (HPS into Nafion matrix by a loading of 0.5 wt % led to a restructured hydrophilic channel, composed of the pendant sulfonic acid groups (–SO3H and the imbedded hydrophilic hollow spheres. The tiny hydrophilic hollow chamber was critical to retaining moisture and facilitating proton transfer in the composite membranes. To obtain such a tiny cavity structure, the synthesis included selective generation of a hydrophilic polymer shell on silica microsphere template and the subsequent removal of the template by etching. The hydrophilic HPS (100–200 nm possessed two different spherical shells, the styrenic network with pendant sulfonic acid groups and with methacrylic acid groups, respectively. By behaving as microreservoirs of water, the hydrophilic HPS promoted the Grotthus mechanism and, hence, enhanced proton transport efficiency through the inter-sphere path. In addition, the HPS with the –SO3H borne shell played a more effective role than those with the –CO2H borne shell in augmenting proton transport, in particular under low humidity or at medium temperatures. Single H2-PEMFC test at 70 °C using dry H2/O2 further verified the impactful role of hydrophilic HPS in sustaining higher proton flux as compared to pristine Nafion membrane.

  5. Preparation and properties of hollow glass microspheres for use in laser fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.H.; Grens, J.Z.; Poco, J.F.

    1983-11-01

    We review the preparation of high quality, hollow-glass microspheres for use in laser driven fusion experiments at LLNL. The primary focus of this paper is on the liquid-droplet method for making glass spheres, which has been in use at LLNL for over six years. We have combined the results from previous studies with our current results to present a detailed description of the preparation and the composition and physical properties of the glass microspheres. We also present a mathematical model that simulates the microsphere formation process. Examples are given of the application of the model to study the effects of various process parameters.

  6. Preparation and properties of hollow glass microspheres for use in laser fusion experiments

    International Nuclear Information System (INIS)

    Campbell, J.H.; Grens, J.Z.; Poco, J.F.

    1983-01-01

    We review the preparation of high quality, hollow-glass microspheres for use in laser driven fusion experiments at LLNL. The primary focus of this paper is on the liquid-droplet method for making glass spheres, which has been in use at LLNL for over six years. We have combined the results from previous studies with our current results to present a detailed description of the preparation and the composition and physical properties of the glass microspheres. We also present a mathematical model that simulates the microsphere formation process. Examples are given of the application of the model to study the effects of various process parameters

  7. Soft-template-synthesis of hollow CuO/Co3O4 composites for pseudo-capacitive electrode: A synergetic effect on electrochemical performance

    Science.gov (United States)

    Wang, Kuaibing; Lv, Bo; Wu, Hua; Luo, Xuefei; Xu, Jiangyan; Geng, Zhirong

    2016-12-01

    Hollow CuO/Co3O4 hybrids, which inherited from its coordination polymer precursor consisting of sheets layer and nanoparticles layer composites, were synthesized and characterized by SEM, EDX, XRD and XPS. To assess its electrochemical capacitive performances, cyclic voltammetry, galvanostatic charging-discharging measurements and A.C. impedance tests were performed successively. The CuO/Co3O4 hybrids had higher capacitance and lower charge transfer resistance than bare Co3O4 nanostructures, revealing that it provided a protection layer and produced a synergistic effect due to the existence of CuO layer. The distinct synergistic effect could be further confirmed by endurance cycling tests. The capacitance of the CuO/Co3O4 hybrids was 111% retained after 500 cycles at a charging rate of 1.0 A g-1 and remained an intense growth trend after 2000 cycles at scan rate of 200 mV s-1.

  8. Syngas fermentation to biofuel: evaluation of carbon monoxide mass transfer and analytical modeling using a composite hollow fiber (CHF) membrane bioreactor.

    Science.gov (United States)

    Munasinghe, Pradeep Chaminda; Khanal, Samir Kumar

    2012-10-01

    In this study, the volumetric mass transfer coefficients (Ka) for CO were examined in a composite hollow fiber (CHF) membrane bioreactor. The mass transfer experiments were conducted at various inlet gas pressures (from 5 to 30 psig (34.5-206.8 kPa(g))) and recirculation flow rates (300, 600, 900, 1200 and 1500 mL/min) through CHF module. The highest Ka value of 946.6 1/h was observed at a recirculation rate of 1500 mL/min and at an inlet gas pressure of 30 psig(206.8 kPa(g)). The findings of this study confirm that the use of CHF membranes is effective and improves the efficiency CO mass transfer into the aqueous phase. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Controllable fabrication and characterization of biocompatible core-shell particles and hollow capsules as drug carrier

    Science.gov (United States)

    Hao, Lingyun; Gong, Xinglong; Xuan, Shouhu; Zhang, Hong; Gong, Xiuqing; Jiang, Wanquan; Chen, Zuyao

    2006-10-01

    SiO 2@CdSe core-shell particles were fabricated by controllable deposition CdSe nanoparticles on silica colloidal spheres. Step-wise coating process was tracked by the TEM and XRD measurements. In addition, SiO 2@CdSe/polypyrrole(PPy) multi-composite particles were synthesized based on the as-prepared SiO 2@CdSe particles by cationic polymerization. The direct electrochemistry of myoglobin (Mb) could be performed by immobilizing Mb on the surface of SiO 2@CdSe particles. Immobilized with Mb, SiO 2@CdSe/PPy-Mb also displayed good bioelectrochemical activity. It confirmed the good biocompatible property of the materials with protein. CdSe hollow capsules were further obtained as the removal of the cores of SiO 2@CdSe spheres. Hollow and porous character of CdSe sub-meter size capsules made them becoming hopeful candidates as drug carriers. Doxorubicin, a typical an antineoplastic drug, was introduced into the capsules. A good sustained drug release behavior of the loading capsules was discovered via performing a release test in the PBS buffer (pH 7.4) solution at 310 k. Furthermore, SiO 2@CdSe/PPy could be converted to various smart hollow capsules via selectively removal of their relevant components.

  10. Li3V2(PO4)3/LiFePO4 composite hollow microspheres for wide voltage lithium ion batteries

    International Nuclear Information System (INIS)

    He, Wen; Wei, Chuanliang; Zhang, Xudong; Wang, Yaoyao; Liu, Qinze; Shen, Jianxing; Wang, Lianzhou; Yue, Yuanzheng

    2016-01-01

    Highlights: • Using yeast cells to control the in-situ growth of crystal particle. • Heterogeneous isomorphism nanocomposite hollow microspheres are synthesized. • The cathode exhibits a higher discharge capacity and energy density. - Abstract: Li 3 V 2 (PO 4 ) 3 (LVP)/LiFePO 4 (LVP) composite hollow microspheres (LVP/LFP-CHMs) for lithium-ion batteries have been synthesized by a combination method, using yeast cells as both structure templates and biocarbon source. The stable heterogeneous isomorphism solid solution with superlattice structure is formed in the joint of LVP and LFP particles. A detailed analysis of the formation mechanism of solid solution with superlattice structure and the influences of different Fe:V mole ratios on the structure and electrochemical properties of composites are presented. When the LVP/LFP-CHMs with a Fe:V mole ratio of 1:3 were used as cathode material in coin cells with metallic Li as anode, the cell exhibits a discharge capacity of 221.5 mAh g −1 for 5 cycles and discharge specific energy of 682 Wh kg −1 at 0.1C in a wide voltage range (1.5–4.3 V). Its capacity is far higher than the capacity of unsubstituted LFP and LVP in the same wide voltage range. The energy density of this cell is about 4 times higher than that of modern commercial lithium-ion batteries (157 Wh kg −1 ). The wide voltage range not only increases the discharge capacity and energy density of cathode materials, but also could expand the range of its applications in electronic equipment.

  11. Reduced graphene oxide-NH2 modified low pressure nanofiltration composite hollow fiber membranes with improved water flux and antifouling capabilities

    Science.gov (United States)

    Li, Xipeng; Zhao, Changwei; Yang, Mei; Yang, Bin; Hou, Deyin; Wang, Tao

    2017-10-01

    Reduced graphene oxide-NH2 (R-GO-NH2), a kind of amino graphene oxide, was embedded into the polyamide (PA) layer of nanofiltration (NF) composite hollow fiber membranes via interfacial polymerization to enhance the permeate flux and antifouling properties of NF membranes under low pressure conditions. In addition, it could mitigate the poor compatibility issue between graphene oxide materials and PA layer. To evaluate the influence of R-GO-NH2 on the performance of the NF composite hollow fiber membrane, SEM, AFM, FTIR, XPS and Zeta potentials were used to characterize the membranes. The results indicated that the compatibility and interactions between R-GO-NH2 and PA layer were enhanced, which was mainly due to the polymerization reaction between amino groups of R-GO-NH2 and acyl chloride groups of TMC. Therefore, salts rejection of the current membranes was improved significantly, and the modified membranes with 50 mg/L R-GO-NH2 demonstrated highest performance in terms of the rejections, which were 26.9%, 98.5%, 98.1%, and 96.1%, for NaCl, Na2SO4, MgSO4, and CaCl2 respectively. It was found that with the R-GO-NH2 contents rasing from 0 to 50 mg/L, pure water flux increased from 30.44 ± 1.71 to 38.57 ± 2.01 L/(m2.h) at 2 bar. What's more, the membrane demonstrated improved antifouling properties.

  12. A facile route to synthesize multiporous MnCo2O4 and CoMn2O4 spinel quasi-hollow spheres with improved lithium storage properties

    Science.gov (United States)

    Li, Jingfa; Xiong, Shenglin; Li, Xiaowei; Qian, Yitai

    2013-02-01

    A facile and general way for the synthesis of porous and hollow complex oxides is highly desirable owing to their significant applications for energy storage and other fields. In this contribution, uniform Mn0.33Co0.67CO3 and Co0.33Mn0.67CO3 microspheres are firstly fabricated solvothermally just by tuning the molar ratio of Mn and Co. Subsequently, the growth of multiporous MnCo2O4 and CoMn2O4 quasi-hollow microspheres by topotactic chemical transformation from the corresponding precursors are realized through a non-equilibrium heat treatment process. Topotactic conversion further demonstrated that the much larger CoMn2O4 pores than those of MnCo2O4 are possibly due to the longer transfer distance of ions. When evaluated as anode materials for LIBs (lithium ion batteries), after 25 cycles at a current density of 200 mA g-1, the resultant MnCo2O4 and CoMn2O4 quasi-hollow microspheres possessed reversible capacities of 755 and 706 mA h g-1, respectively. In particular, the MnCo2O4 samples could deliver a reversible capacity as high as 610 mA h g-1 even at a higher current density of 400 mA g-1 with excellent electrochemical stability after 100 cycles of testing, indicating its potential application in LIBs. We believe that such good performance results from the appropriate pore size and quasi-hollow nature of MnCo2O4 microspheres, which can effectively buffer the large volume variation of anodes based on the conversion reaction during Li+ insertion/extraction. The present strategy is simple but very effective, and due to its versatility, it can be extended to other binary, even ternary complex metal oxides with high-performance in LIBs.A facile and general way for the synthesis of porous and hollow complex oxides is highly desirable owing to their significant applications for energy storage and other fields. In this contribution, uniform Mn0.33Co0.67CO3 and Co0.33Mn0.67CO3 microspheres are firstly fabricated solvothermally just by tuning the molar ratio of Mn and Co

  13. Influence of the radial spacing between cathodes on the surface composition of iron samples sintered by hollow cathode electric discharge

    Directory of Open Access Journals (Sweden)

    Brunatto S.F.

    2001-01-01

    Full Text Available The present work reports an investigation of the influence of the radial spacing between cathodes on the iron sintering process by hollow cathode electrical discharge, with surface enrichment of the alloying elements Cr and Ni. Pressed cylindrical samples of 9.5 mm diameter and density of 7.0 ± 0.1 g/cm³ were prepared by compaction of Ancorsteel 1000C iron powder. These samples, constituting the central cathode, were positioned concentrically in the interior of an external cathode machined from a tube of stainless steel AISI 310 (containing: 25% Cr, 16% Ni, 1.5% Mn, 1.5% Si, 0.03% C and the remainder Fe. Sintering was done at 1150 °C, for 120 min, utilizing radial spacings between the central and hollow cathodes of 3, 6 and 9 mm and a gas mixture of 80% Ar and 20% H2, with a flow rate of 5 cm³/s at a pressure of 3 Torr. The electric discharge was generated using a pulsed voltage power source, with a period of 200 mus. The radial spacing had only a slight influence on the quantity of atoms of alloying elements deposited and diffused on the surface of the sample. Analysis with a microprobe showed the presence of chrome (up to 4.0% and nickel (up to 3.0%, in at. % at the surface of the samples. This surface enrichment can be attributed to the mechanism of sputtering of the metallic atoms present in the external cathode, with the deposition of these elements on the sample surface and consequent diffusion within the sample.

  14. Hydrothermal assisted synthesis of iron oxide-based magnetic silica spheres and their performance in magnetophoretic water purification

    Energy Technology Data Exchange (ETDEWEB)

    Caparros, C., E-mail: ccaparros@fisica.uminho.pt [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Benelmekki, M.; Martins, P.M. [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Xuriguera, E. [Facultat de Quimica, Universitat de Barcelona, 08028 Barcelona (Spain); Silva, C.J.R. [Departamento de Quimica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Martinez, Ll.M. [Sepmag Technologies, Parc Tecnologic del Valles, 08290 Barcelona (Spain); Lanceros-Mendez, S. [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2012-08-15

    Porous Magnetic Silica (PMS) spheres of about 400 nm diameter were synthesised by one-pot process using the classical Stber method combined with hydrothermal treatment. Maghemite nanoparticles ({gamma}-Fe{sub 2}O{sub 3}) were used as fillers and cetyltrimethylammonium bromide (CTAB) was used as templating agent. The application of the hydrothermal process (120 Degree-Sign C during 48 h) before the calcination leads to the formation of homogeneous and narrow size distribution PMS spheres. X-ray diffraction patterns (XRD), Infrared measurements (FTIR) and Transmission Electron microscopy (TEM) methods were used to determine the composition and morphology of the obtained PMS spheres. The results show a homogeneous distribution of the {gamma}-Fe{sub 2}O{sub 3} nanoparticles in the silica matrix with a 'hollow-like' morphology. Magnetophoresis measurements at 60 T m{sup -1} show a total separation time of the PMS spheres suspension of about 16 min. By using this synthesis method, the limitation of the formation of silica spheres without incorporation of magnetic nanoparticles is overcome. These achievements make this procedure interesting for industrial up scaling. The obtained PMS spheres were evaluated as adsorbents for Ni{sup 2+} in aqueous solution. Their adsorption capacity was compared with the adsorption capacity of magnetic silica spheres obtained without hydrothermal treatment before calcination process. PMS spheres show an increase of the adsorption capacity of about 15% of the initial dissolution of Ni{sup 2+} without the need to functionalize the silica surface. Highlights: Black-Right-Pointing-Pointer Homogeneous and controlled size porous magnetic silica spheres were obtained. Black-Right-Pointing-Pointer Magnetophoretic removing of Ni{sup 2+} processes was successfully preformed at HLGMF. Black-Right-Pointing-Pointer PMS show higher Ni{sup 2+} removing capacity than spheres without hydrothermal treatment. Black-Right-Pointing-Pointer PMS can be

  15. Development of robust fluorinated TiO2/PVDF composite hollow fiber membrane for CO2 capture in gas-liquid membrane contactor

    Science.gov (United States)

    Lin, Yuqing; Xu, Yilin; Loh, Chun Heng; Wang, Rong

    2018-04-01

    Gas-liquid membrane contactor (GLMC) is a promising method to attain high efficiency for CO2 capture from flue gas, biogas and natural gas. However, membranes used in GLMC are prone to pore wetting due to insufficient hydrophobicity and low chemical resistance, resulting in significant increase in mass transfer resistance. To mitigate this issue, inorganic-organic fluorinated titania/polyvinylidene fluoride (fTiO2/PVDF) composite hollow fiber (HF) membranes was prepared via facile in-situ vapor induced hydrolyzation method, followed by hydrophobic modification. The proposed composite membranes were expected to couple the superb chemical stability of inorganic and high permeability/low cost of organic materials. The continuous fTiO2 layer deposited on top of PVDF substrate was found to possess a tighter microstructure and better hydrophobicity, which effectively prevented the membrane from wetting and lead to a high CO2 absorption flux (12.7 × 10-3 mol m-2 s-1). In a stability test with 21-day operation of GLMC using 1M monoethanolamine (MEA) as the absorbent, the fTiO2/PVDF membrane remained to be intact with a CO2 absorption flux decline of ∼16%, while the pristine PVDF membrane suffered from a flux decline of ∼80% due to membrane damage. Overall, this work provides an insight into the preparation of high-quality inorganic/organic composite HF membranes for CO2 capture in GLMC application.

  16. Nonstoichiometric Zn Ferrite and ZnFe2O4/Fe2O3 Composite Spheres: Preparation, Magnetic Properties, and Chromium Removal

    Science.gov (United States)

    Hang, Chun-Liang; Yang, Li-Xia; Sun, Chang-Mei; Liang, Ying

    2018-03-01

    Monodisperse and porous nonstoichiometric Zn ferrite can be prepared by a solvothermal method. Such non-Zn ferrite was used to be the precursor for synthesis of ZnFe2O4/Fe2O3 composite via calcination at 600°C for 3 h in air. X-ray powder diffractometer (XRD) and Energy Dispersive Spectrometer (EDS) proved the nonstoichiometry of Zn ferrite synthesized by solvothermal method and the formation of ZnFe2O4/Fe2O3 composite via calcination. TEM image showed that non-Zn ferrite spheres with wormlike nanopore structure were made of primary nanocrystals. BET surface area of non-Zn ferrite was much higher than that of ZnFe2O4/Fe2O3 composite. Saturation magnetization of non-Zn ferrites was significantly higher than that of ZnFe2O4/Fe2O3 composites. Calcination of non-Zn ferrite resulted in the formation of large amount of non-magnetic Fe2O3,which caused a low magnetization of composite. Because of higher BET surface area and higher saturation magnetization, non-Zn ferrite presented better Cr6+ adsorption property than ZnFe2O4/Fe2O3 composites.

  17. Synthesis of Hollow Silica by Stober Method with Double Polymers as Templates

    International Nuclear Information System (INIS)

    Nguyen, Anhthu; Park, Chang Woo; Kim, Sang Hern

    2014-01-01

    The hollow SiO 2 spheres with uniform size were synthesized by a modified stoeber method under the control of polyelectrolytes (PSS and PAA) as templates. This synthetic route includes the formation of spherical colloid micelle in ethanol solution, hydrolysis of TEOS under control of ammonia, and the removal of polyelectrolyte by washing or calcination. Hollow silica spheres with controllable core diameters between 100 and 270 nm and wall thickness between 15 and 50 nm have been synthesized. The influence of template solution concentration and solvent and dispersant on the formation of silica hollow spheres is studied and reported in detail

  18. Hollow fiber membranes and methods for forming same

    Science.gov (United States)

    Bhandari, Dhaval Ajit; McCloskey, Patrick Joseph; Howson, Paul Edward; Narang, Kristi Jean; Koros, William

    2016-03-22

    The invention provides improved hollow fiber membranes having at least two layers, and methods for forming the same. The methods include co-extruding a first composition, a second composition, and a third composition to form a dual layer hollow fiber membrane. The first composition includes a glassy polymer; the second composition includes a polysiloxane; and the third composition includes a bore fluid. The dual layer hollow fiber membranes include a first layer and a second layer, the first layer being a porous layer which includes the glassy polymer of the first composition, and the second layer being a polysiloxane layer which includes the polysiloxane of the second composition.

  19. Hollow MEMS

    DEFF Research Database (Denmark)

    Larsen, Peter Emil

    Miniaturization of electro mechanical sensor systems to the micro range and beyond has shown impressive sensitivities measuring sample properties like mass, viscosity, acceleration, pressure and force just to name a few applications. In order to enable these kinds of measurements on liquid samples...... a hollow MEMS sensor has been designed, fabricated and tested. Combined density, viscosity, buoyant mass spectrometry and IR absorption spectroscopy are possible on liquid samples and micron sized suspended particles (e.g. single cells). Measurements are based on changes in the resonant behavior...... of these sensors. Optimization of the microfabrication process has led to a process yield of almost 100% .This is achieved despite the fact, that the process still offers a high degree of flexibility. By simple modifications the Sensor shape can be optimized for different size ranges and sensitivities...

  20. Stem/progenitor cells derived from the cochlear sensory epithelium give rise to spheres with distinct morphologies and features.

    Science.gov (United States)

    Diensthuber, Marc; Oshima, Kazuo; Heller, Stefan

    2009-06-01

    Nonmammalian vertebrates regenerate lost sensory hair cells by means of asymmetric division of supporting cells. Inner ear or lateral line supporting cells in birds, amphibians, and fish consequently serve as bona fide stem cells resulting in high regenerative capacity of hair cell-bearing organs. Hair cell regeneration does not happen in the mammalian cochlea, but cells with proliferative capacity can be isolated from the neonatal cochlea. These cells have the ability to form clonal floating colonies, so-called spheres, when cultured in nonadherent conditions. We noticed that the sphere population derived from mouse cochlear sensory epithelium cells was heterogeneous, consisting of morphologically distinct sphere types, hereby classified as solid, transitional, and hollow. Cochlear sensory epithelium-derived stem/progenitor cells initially give rise to small solid spheres, which subsequently transition into hollow spheres, a change that is accompanied by epithelial differentiation of the majority of sphere cells. Only solid spheres, and to a lesser extent, transitional spheres, appeared to harbor self-renewing stem cells, whereas hollow spheres could not be consistently propagated. Solid spheres contained significantly more rapidly cycling Pax-2-expressing presumptive otic progenitor cells than hollow spheres. Islet-1, which becomes upregulated in nascent sensory patches, was also more abundant in solid than in hollow spheres. Likewise, hair cell-like cells, characterized by the expression of multiple hair cell markers, differentiated in significantly higher numbers in cell populations derived from solid spheres. We conclude that cochlear sensory epithelium cell populations initially give rise to small solid spheres that have self-renewing capacity before they subsequently convert into hollow spheres, a process that is accompanied by loss of stemness and reduced ability to spontaneously give rise to hair cell-like cells. Solid spheres might, therefore, represent

  1. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  2. A four-functional composite-hierarchical anatase TiO2 microsphere consisting of nanoparticles, nanowires and submicron ellipsoidal spheres for Dye Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Huang, Niu; Chen, Feitai; Sun, Panpan; Sun, Xiaohua; Sebo, Bobby; Zhao, Xingzhong

    2014-01-01

    Graphical abstract: - Abstract: In this paper, we prepare a composite-hierarchical microsphere (HMS) which is composed of two kinds of HMSs: one flower-like microsphere (FMS, ∼1.5 μm, containing nanoparticles and nanowires) and plentiful mesoporous submicron ellipsoidal spheres (ESs, ∼200 nm, assembled with nanoparticles) which are embedded evenly in the FMS. For comparing, pure FMS and ES are prepared, respectively. It is found that the composite-HMS possesses (a) the highest BET surface area, (b) the highest light scattering ability, (c) the fastest electron transport and the longest electron life time, and (d) light trapping ability enabled by multiple light reflection and scattering between ESs and nanowires inside each FMS*ESs particle. The energy conversion efficiency of 7.91% of the DSSC based on FMS*ESs is higher than devices based on ES and FMS (7.22% and 7.24%, respectively), which also benefits from the structural advantages of the composite-HMS compared with non-composite HMSs

  3. Tailored synthesis of monodispersed nano/submicron porous silicon oxycarbide (SiOC) spheres with improved Li-storage performance as an anode material for Li-ion batteries

    Science.gov (United States)

    Shi, Huimin; Yuan, Anbao; Xu, Jiaqiang

    2017-10-01

    A spherical silicon oxycarbide (SiOC) material (monodispersed nano/submicron porous SiOC spheres) is successfully synthesized via a specially designed synthetic strategy involving pyrolysis of phenyltriethoxysilane derived pre-ceramic polymer spheres at 900 °C. In order to prevent sintering of the pre-ceramic polymer spheres upon heating, a given amount of hollow porous SiO2 nanobelts which are separately prepared from tetraethyl orthosilicate with CuO nanobelts as templates are introduced into the pre-ceramic polymer spheres before pyrolysis. This material is investigated as an anode for lithium-ion batteries in comparison with the large-size bulk SiOC material synthesized under the similar conditions but without hollow SiO2 nanobelts. The maximum reversible specific capacity of ca. 900 mAh g-1 is delivered at the current density of 100 mA g-1 and ca. 98% of the initial capacity is remained after 100 cycles at 100 mA g-1 for the SiOC spheres material, which are much superior to the bulk SiOC material. The improved lithium storage performance in terms of specific capacity and cyclability is attributed to its particular morphology of monodisperse nano/submicron porous spheres as well as its modified composition and microstructure. This SiOC material has higher Li-storage activity and better stability against volume expansion during repeated lithiation and delithiation cycling.

  4. Controllable Synthesis of Functional Hollow Carbon Nanostructures with Dopamine As Precursor for Supercapacitors.

    Science.gov (United States)

    Liu, Chao; Wang, Jing; Li, Jiansheng; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

    2015-08-26

    N-doped hollow carbon spheres (N-HCSs) are promising candidates as electrode material for supercapacitor application. In this work, we report a facile one-step synthesis of discrete and highly dispersible N-HCSs with dopamine (DA) as a carbon precursor and TEOS as a structure-assistant agent in a mixture containing water, ethanol, and ammonia. The architectures of resultant N-HCSs, including yolk-shell hollow carbon spheres (YS-HCSs), single-shell hollow carbon spheres (SS-HCSs), and double-shells hollow carbon spheres (DS-HCSs), can be efficiently controlled through the adjustment of the amount of ammonia. To explain the relation and formation mechanism of these hollow carbon structures, the samples during the different synthetic steps, including polymer/silica spheres, carbon/silica spheres and silica spheres by combustion in air, were characterized by TEM. Electrochemical measurements performed on YS-HCSs, SS-HCSs, and DS-HCSs showed high capacitance with 215, 280, and 381 F g(-1), respectively. Moreover, all the nitrogen-doped hollow carbon nanospheres showed a good cycling stability 97.0% capacitive retention after 3000 cycles. Notably, the highest capacitance of DS-HCSs up to 381 F g(-1) is higher than the capacitance reported so far for many carbon-based materials, which may be attributed to the high surface area, hollow structure, nitrogen functionalization, and double-shell architecture. These kinds of N-doped hollow-structured carbon spheres may show promising prospects as advanced energy storage materials and catalyst supports.

  5. Porous-wall hollow glass microspheres as carriers for biomolecules

    Science.gov (United States)

    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.

  6. Mercury - the hollow planet

    Science.gov (United States)

    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

  7. Composition-property relationships in multifunctional hollow mesoporous carbon nanosystems for PH-responsive magnetic resonance imaging and on-demand drug release

    Science.gov (United States)

    Zhang, Shengjian; Qian, Xiaoqing; Zhang, Linlin; Peng, Weijun; Chen, Yu

    2015-04-01

    The construction of intelligent stimuli-responsive nanosystems can substantially improve the sensitivity/resolution/specificity of diagnostic imaging and enhance the therapeutic efficiency of chemotherapy for cancer treatment. This work reports on a generic construction strategy to achieve a multiple stimuli-responsive theranostic system for cancer simply by optimizing the chemical compositions of inorganic nanoplatforms to avoid the tedious and complicated synthetic procedure for traditional organic or organic/inorganic nanosystems. Based on the ``breaking up'' nature of manganese oxides and specific features of the carbonaceous framework to interact with aromatic drug molecules, manganese oxide nanoparticles were elaborately integrated into hollow mesoporous carbon nanocapsules by a simple in situ framework redox strategy to realize concurrent pH-sensitive T1-weighted magnetic resonance imaging (MRI) and pH-/HIFU-responsive on-demand drug release. The ultrasensitive disease-triggered MRI performance has been successfully demonstrated by a 52.5-fold increase of longitudinal relaxivity (r1 = 10.5 mM-1 s-1) and on nude mice 4T1 xenograft. The pH- and HIFU-triggered doxorubicin release and enhanced therapeutic outcome against multidrug resistance of cancer cells were systematically confirmed. In particular, the fabricated inorganic composite nanocapsules were found to feature unique biological behaviours, such as antimetastasis effect, extremely low hemolysis against red blood cells and high in vivo histocompatibility. This report on the successful construction of a pure inorganic nanosystem with multiple stimuli-responsivenesses may pave the way to new methods for the development of intelligent nanofamilies for cancer therapy.The construction of intelligent stimuli-responsive nanosystems can substantially improve the sensitivity/resolution/specificity of diagnostic imaging and enhance the therapeutic efficiency of chemotherapy for cancer treatment. This work reports

  8. One-step synthesis of in situ reduced metal Bi decorated bismuth molybdate hollow microspheres with enhancing photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Meng [College of Chemistry & Chemical Engineering, Chongqing University, Chongqing 400044 (China); Lu, Shiyu [Institute for Clean Energy & Advanced Materials, Faculty of Materials and Energy, Southwest University, Chongqing, 400715 (China); Ma, Li, E-mail: mlsys607@126.com [College of Chemistry & Chemical Engineering, Chongqing University, Chongqing 400044 (China); Gan, Mengyu [College of Chemistry & Chemical Engineering, Chongqing University, Chongqing 400044 (China)

    2017-02-28

    Highlights: • Metal Bi decorated Bi{sub 2-x}MoOy was synthesised by a simple and one-step. • Bi{sup 3+} could be in situ reduced to Bi{sup 0} gradually and dispersed uniform in Bi{sub 2-x}MoOy. • It shows excellent photocatalytic activity due to special structure and composition. - Abstract: In this feature work, in situ metal Bi are successfully modified bismuth molybdate hollow spheres using an effective one-pot solvthermal reduction without any temple. In order to deeply understand the influence of reduction conditions on the texture, surface state, and photocatalytic performance of the resulting samples, a series of products were synthesized by tuning the temperatures. The similar morphology, surface area of photocatalysis (BMO-160 and BMO-170) were synthesized, only with the different composition. The detailed characterization and analysis distinctly suggested that increasing solvothermal reduction temperature led to Bi{sup 3+} was in situ reduced to elementary substance Bi{sup 0} by ethylene glycol gradually and dispersed very uniform in bismuth molybdate. Benefiting from the enhanced charge separation, transfer, and donor density resulting from the formation of Bi decorated bismuth molybdate where Bi as cocatalyst, the photocatalytic performance of the reductive Bi/Bi{sub 2-x}MoO{sub y} hollow spheres (BMO-170) is higher than that of the untreated Bi{sub 2-x}MoO{sub y} hollow spheres (BMO-160) for Rh6G degradation under visible light irradiation. Additionally, the reductive BMO-170 has a superior stability after five cycles.

  9. Superconducting Sphere in an External Magnetic Field Revisited

    Science.gov (United States)

    Sazonov, Sergey N.

    2013-01-01

    The purpose of this article is to give the intelligible procedure for undergraduate students to grasp proof of the fact that the magnetic field outside the hollow superconducting sphere (superconducting shell) coincides with the field of a point magnetic dipole both when an uniform external magnetic field is applied as when a ferromagnetic sphere…

  10. Electric field-assisted formation of organically modified hydroxyapatite (ormoHAP) spheres in carboxymethylated gelatin gels.

    Science.gov (United States)

    Heinemann, C; Heinemann, S; Kruppke, B; Worch, H; Thomas, J; Wiesmann, H P; Hanke, T

    2016-10-15

    A biomimetic strategy was developed in order to prepare organically modified hydroxyapatite (ormoHAP) with spherical shape. The technical approach is based on electric field-assisted migration of calcium ions and phosphate ions into a hydrogel composed of carboxymethylated gelatin. The electric field as well as the carboxymethylation using glucuronic acid (GlcA) significantly accelerates the mineralization process, which makes the process feasible for lab scale production of ormoHAP spheres and probably beyond. A further process was developed for gentle separation of the ormoHAP spheres from the gelatin gel without compromising the morphology of the mineral. The term ormoHAP was chosen since morphological analyses using electron microscopy (SEM, TEM) and element analysis (EDX, FT-IR, XRD) confirmed that carboxymethylated gelatin molecules use to act as organic templates for the formation of nanocrystalline HAP. The hydroxyapatite (HAP) crystals self-organize to form hollow spheres with diameters ranging from 100 to 500nm. The combination of the biocompatible chemical composition and the unique structure of the nanocomposites is considered to be a useful basis for future applications in functionalized degradable biomaterials. A novel bioinspired mineralization process was developed based on electric field-assisted migration of calcium and phosphate ions into biochemically carboxymethylated gelatin acting as organic template. Advantages over conventional hydroxyapatite include particle size distribution and homogeneity as well as achievable mechanical properties of relevant composites. Moreover, specifically developed calcium ion or phosphate ion release during degradation can be useful to adjust the fate of bone cells in order to manipulate remodeling processes. The hollow structure of the spheres can be useful for embedding drugs in the core, encapsulated by the highly mineralized outer shell. In this way, controlled drug release could be achieved, which enables

  11. Simple synthesis of Al{sub 2}O{sub 3} sphere composite from hybrid process with improved thermal stability for catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Regina C.R., E-mail: reginaclaudiasantos@yahoo.com.br [Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceará, Campus of Pici, Fortaleza, CE, CEP: 60440-554 (Brazil); Pinheiro, Antônio N.; Leite, Edson R. [Department of Chemistry, Federal University of São Carlos, São Carlos, SP, CEP: 13560-905 (Brazil); Freire, Valder N. [Department of Physics, Federal University of Ceará, Campus of Pici, Fortaleza, CE, CEP: 60440-554 (Brazil); Longhinotti, Elisane; Valentini, Antoninho [Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceará, Campus of Pici, Fortaleza, CE, CEP: 60440-554 (Brazil)

    2015-06-15

    Aluminium oxide spheres were synthesized by the hybrid process applying the biopolymer chitosan. After the calcination process the porous spheres were characterized by Chemical elemental analysis (XRF), X-ray diffraction (XRD), Scanning electron microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), N{sub 2} adsorption–desorption isotherms, infrared spectroscopy (IR), and CO{sub 2} temperature programmed desorption (CO{sub 2}-TPD). The effect of thermal treatment on surface properties of the oxide spheres was also evaluated by the catalytic ethanol dehydration reaction. The hybrid method produced interesting results related to the thermal stability against sintering process and consequently low decreases of surface area. The hybrid spheres calcination at 900 and 1200 °C produced a metastable phases of alumina with a high surface area, and nanometric crystallites. Additionally, the spheres of mixed silica-alumina synthesized by this method reveal the formation of porous spheres with highly acidic OH groups, which was suggested by the catalytic performance. - Highlights: • Al and Si/Al oxide spheres with promising properties are synthesized by hybrid method. • Al{sub 2}O{sub 3} spheres show high thermal stability and resistance the loss surface area. • The SiO{sub 2} addition plays an important role in the structure and porosity of the spheres. • Al{sub 2}O{sub 3} and SiO{sub 2}/Al{sub 2}O{sub 3} spheres presented a good activity to conversion ethanol. • The activity is related to the surface area and density of OH groups on surface.

  12. Flexible three-dimensional electrodes of hollow carbon bead strings as graded sulfur reservoirs and the synergistic mechanism for lithium–sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dan [College of Materials Science and Engineering, Sichuan University, Chengdu, 610064 (China); Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900 (China); Ni, Wei, E-mail: niwei@iccas.ac.cn [Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900 (China); Cheng, Jianli; Wang, Zhuanpei; Wang, Ting; Guan, Qun [Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900 (China); Zhang, Yun, E-mail: y_zhang@scu.edu.cn [College of Materials Science and Engineering, Sichuan University, Chengdu, 610064 (China); Wu, Hao [College of Materials Science and Engineering, Sichuan University, Chengdu, 610064 (China); Li, Xiaodong [Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900 (China); Wang, Bin, E-mail: edward.bwang@gmail.com [Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, 621900 (China)

    2017-08-15

    Graphical abstract: Flexible three-dimensional electrode comprised of stringed N-doped hollow carbon spheres shows a synergistic sulfur confinement mechanism and a higher energy/power density for the promising lithium-sulfur batteries compared with traditional electrodes. - Highlights: • Hollow carbon beads on string structure was first prepared. • Flexible 3D electrodes as graded reservoirs for polysulfides were conducted. • Synergistic effect for enhanced polysulfides storage was claimed. - Abstract: Three-dimensional (3D) flexible electrodes of stringed hollow nitrogen-doped (N-doped) carbon nanospheres as graded sulfur reservoirs and conductive frameworks were elaborately designed via a combination of the advantages of hollow structures, 3D electrodes and flexible devices. The as-prepared electrodes by a synergistic method of electrospinning, template sacrificing and activation for Li–S batteries without any binder or conductive additives but a 3D interconnected conductive network offered multiple transport paths for electrons and improved sulfur utilization and facilitated an easy access to Li{sup +} ingress/egress. With the increase of density of hollow carbon spheres in the strings, the self-supporting composite electrode reveals an enhanced synergistic mechanism for sulfur confinement and displays a better cycling stability and rate performance. It delivers a high initial specific capacity of 1422.6 mAh g{sup −1} at the current rate of 0.2C with the high sulfur content of 76 wt.%, and a much higher energy density of 754 Wh kg{sup −1} and power density of 1901 Wh kg{sup −1}, which greatly improve the energy/power density of traditional lithium–sulfur batteries and will be promising for further commercial applications.

  13. MnO{sub 2}@colloid carbon spheres nanocomposites with tunable interior architecture for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuxin, E-mail: zhangyuxin@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Key Laboratory of Fundamental Science of Micro/Nano-Devices and System Technology, Chongqing University, Chongqing 400044 (China); Dong, Meng; Zhu, Shijin [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Liu, Chuanpu, E-mail: liuchuanpu@163.com [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Wen, Zhongquan [National Key Laboratory of Fundamental Science of Micro/Nano-Devices and System Technology, Chongqing University, Chongqing 400044 (China)

    2014-01-01

    Graphical abstract: - Highlights: • MnO{sub 2}@CSs nanocomposites have been successfully synthesized in room temperature. • The composites exhibited three structures: core–shell, yolk–shell and hollow structure. • The yolk–shell structure exhibited a high specific capacitance and cycling stability. - Abstract: MnO{sub 2}@colloid carbon spheres nanocomposites with tunable interior architecture have been synthesized by a facile and cost-effective strategy at room temperature. The structure and morphology of as-prepared nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption, focused ion beam scanning electron microscopy (FIB/SEM) and high-resolution transmission electron microscopy (HRTEM). The as-obtained composites exhibited a three-dimensional architecture with core–shell, yolk–shell and hollow interior structure. Furthermore, the electrochemical properties of composites were evaluated by cycle voltammetric (CV) and galvanostatic charge–discharge measurements. The yolk–shell structure exhibited the optimized pseudocapacitance performance, revealing a specific capacitance (273 F g{sup −1}) with a good rate and cycling stability, owing to its unique structure and the poor crystallinity of MnO{sub 2} nanofilms. Therefore, this facile synthetic strategy could be useful to design and synthesis of tunable nanostructures with enhanced supercapacitor behavior.

  14. MnO2@colloid carbon spheres nanocomposites with tunable interior architecture for supercapacitors

    International Nuclear Information System (INIS)

    Zhang, Yuxin; Dong, Meng; Zhu, Shijin; Liu, Chuanpu; Wen, Zhongquan

    2014-01-01

    Graphical abstract: - Highlights: • MnO 2 @CSs nanocomposites have been successfully synthesized in room temperature. • The composites exhibited three structures: core–shell, yolk–shell and hollow structure. • The yolk–shell structure exhibited a high specific capacitance and cycling stability. - Abstract: MnO 2 @colloid carbon spheres nanocomposites with tunable interior architecture have been synthesized by a facile and cost-effective strategy at room temperature. The structure and morphology of as-prepared nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption, focused ion beam scanning electron microscopy (FIB/SEM) and high-resolution transmission electron microscopy (HRTEM). The as-obtained composites exhibited a three-dimensional architecture with core–shell, yolk–shell and hollow interior structure. Furthermore, the electrochemical properties of composites were evaluated by cycle voltammetric (CV) and galvanostatic charge–discharge measurements. The yolk–shell structure exhibited the optimized pseudocapacitance performance, revealing a specific capacitance (273 F g −1 ) with a good rate and cycling stability, owing to its unique structure and the poor crystallinity of MnO 2 nanofilms. Therefore, this facile synthetic strategy could be useful to design and synthesis of tunable nanostructures with enhanced supercapacitor behavior

  15. Morphology conserving aminopropyl functionalization of hollow silica nanospheres in toluene

    Science.gov (United States)

    Dobó, Dorina G.; Berkesi, Dániel; Kukovecz, Ákos

    2017-07-01

    Inorganic nanostructures containing cavities of monodisperse diameter distribution find applications in e.g. catalysis, adsorption and drug delivery. One of their possible synthesis routes is the template assisted core-shell synthesis. We synthesized hollow silica spheres around polystyrene cores by the sol-gel method. The polystyrene template was removed by heat treatment leaving behind a hollow spherical shell structure. The surface of the spheres was then modified by adding aminopropyl groups. Here we present the first experimental evidence that toluene is a suitable alternative functionalization medium for the resulting thin shells, and report the comprehensive characterization of the amino-functionalized hollow silica spheres based on scanning electron microscopy, transmission electron microscopy, N2 adsorption, FT-IR spectroscopy, Raman spectroscopy and electrokinetic potential measurement. Both the presence of the amino groups and the preservation of the hollow spherical morphology were unambiguously proven. The introduction of the amine functionality adds amphoteric character to the shell as shown by the zeta potential vs. pH function. Unlike pristine silica particles, amino-functionalized nanosphere aqueous sols can be stable at both acidic and basic conditions.

  16. Hierarchical flower-like carbon nanosheet assembly with embedded hollow NiCo{sub 2}O{sub 4} nanoparticles for high- performance lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Ling; Qiu, Huajun; Luo, Pan; Li, Wenxiang; Zhang, Huijuan; Wang, Yu, E-mail: wangy@cqu.edu.cn

    2017-05-01

    Highlights: • Flower-like NiCo{sub 2}O{sub 4}@carbon nanosphere is firstly synthesized for Li-ion batteries. • The nanostructure exhibits the unique feature of hollow NiCo{sub 2}O{sub 4} nanoparticles embedded inside and graphitized carbon layers coating outside. • The sample reveals stable structure, large specific surface area and good electrical conductivity. • The composite exhibits superior rate capability, cycling capacity and excellent Coulombic efficiency. - Abstract: The fabrication of closely bounded metal oxides/carbon hybrid nano-structures is significant for its use in energy-related areas especially lithium ion batteries (LIBs). In this research, a flower-like carbon sphere with hollow NiCo{sub 2}O{sub 4} nanoparticles encapsulated inside the carbon thin nanopetal is fabricated by using a mixed basic carbonate nickel and cobalt sphere as the precursor and templates followed by the outer carbon membrane covering and two-step calcination process. When tested as anode material for LIBs, this flower-like carbon-based hybrid sphere demonstrates a significantly enhanced reversible capacity and cycling stability at various current densities.

  17. The Processing of Titanium Hydride Powders into Uniform Hollow Spheres

    National Research Council Canada - National Science Library

    Hurysz, Kevin

    1998-01-01

    .... Slurry suitability is dictated by the solids loading and degree of dispersion, the influence of polymer additives on rheology and the evaporation of acetone, and the minimization of impurities...

  18. Characterization of silane coated hollow sphere alumina-reinforced ...

    Indian Academy of Sciences (India)

    Unknown

    in clinical practice, which depends on the magnitude of the applied load, the ... component design for its excellent wear and corrosion resistance (Chandra et al ... The nearly uniform distribution of particles in the com- posite was checked using ...

  19. Comportement des poteaux composites en profils creux en acier remplis de béton Behavior of composite columns in hollow steel section filled with concrete

    Directory of Open Access Journals (Sweden)

    Othmani N.

    2012-09-01

    Full Text Available Le but de cet article, est la determination des rigidites flexionnelles EIx et EIy d’fune section mixte acier beton et plus precisement d’fun poteau en tube d’facier de section rectangulaire, remplie de beton, sollicitee a la flexion bi-axiale (N, Mx et My. L’festimation des rigidites sera faite a partir d’fune approche theorique par une analyse du poteau en elements finis (element barre a 4 degres de liberte, basee sur les conditions d’fequilibres a mi-portee en utilisant la relation moment-courbure (M–Φ de l’felement deforme par application de l’fequation suivante: EI=M/Φ. Le comportement des materiaux est celui comme adopte par les reglements Eurocode 2 et 3, respectivement pour le beton et l’facier. Afin de valider l’fapproche theorique utilisee dans cette etude, deux comparaisons ont ete faites : une premiere permettant de comparer les resultats des rigidites determinees par les relations moments courbures et celles calculees par l’fEurocode 4 et une deuxieme comparaison entre les charges de ruines de deux poteaux de grandeurs natures avec ceux testes au laboratoire [2]. Au vu des resultats obtenus, nous pouvons conclure que l’approche théorique utilisée dans cette étude ainsi que les modèles de comportement des matériaux sont adéquats pour ce genre de problèmes. The purpose of this paper is the determination of flexural stiffness EIx and EIy of a concrete filled rectangular cross section of a composite steel column, under biaxial bending (N, Mx and My. The rigidities will be estimated from a theoretical approach using a finite element analysis (element bar with 4 degrees of freedom, based on the equilibrium conditions at mid-span using the moment-curvature relationships (M–Φ of the deformed element by applying the following equation: EI=M/Φ. The material behavior is the one adopted by Eurocode 2 and 3, respectively, for concrete and steel. To validate the theoretical approach used, two comparisons

  20. Synthesis of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres via homogeneous precipitation route

    Directory of Open Access Journals (Sweden)

    Peng-Fei Ai, Ying-Liang Liu, Li-Yuan Xiao, Hou-Jin Wang and Jian-Xin Meng

    2010-01-01

    Full Text Available A phosphorescent material in the form of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres was prepared by homogeneous precipitation using monodispersed carbon spheres as hard templates. Y2O3:Eu3+ hollow microspheres were first synthesized to serve as the precursor. Y2O2S:Eu3+, Mg2+, Ti4+ powders were obtained by calcinating the precursor in a CS2 atmosphere. The crystal structure, morphology and optical properties of the composites were characterized. X-ray diffraction measurements confirmed the purity of the Y2O2S phase. Electron microscopy observations revealed that the Y2O2S:Eu3+, Mg2+, Ti4+ particles inherited the hollow spherical shape from the precursor after being calcined in a CS2 atmosphere and that they had a diameter of 350–450 nm and a wall thickness of about 50–80 nm. After ultraviolet radiation at 265 or 325 nm for 5 min, the particles emitted strong red long-lifetime phosphorescence originating from Eu3+ ions. This phosphorescence is associated with the trapping of charge carriers by Ti4+ and Mg2+ ions.

  1. Radioactive spheres without inactive wall for lesion simulation in PET

    International Nuclear Information System (INIS)

    Bazanez-Borgert, M.; Bundschuh, R.A.; Herz, M.; Martinez, M.J.; Schwaiger, M.; Ziegler, S.I.

    2008-01-01

    With the growing importance of PET and PET/CT in diagnosis, staging, therapy monitoring and radiotherapy planning, appropriate tools to simulate lesions in phantoms are important. Normally hollow spheres, made of plastic or glass, which can be filled with radioactive solutions, are used. As these spheres have an inactive wall they do not reflect the real situation in the patient and lead to quantification errors in the presence of background activity. We propose spheres made of radioactive wax, which are easy to produce, give a high flexibility to the user and a more accurate quantification. These wax spheres were evaluated for their applicability in PET phantoms and it was found that the activity is not diffusing into the surrounding water in relevant quantities, that they show a sufficient homogeneity, and that their attenuation properties are equivalent to water for photons of PET energies. Recovery coefficients for the wax spheres were measured and compared with those obtained for fillable plastic spheres for diameters of 28, 16, 10, and 6 mm in the presence of background activity. Recovery coefficients of the wax spheres were found to be up to 21% higher than for the fillable spheres. (orig.)

  2. Shape evolution of new-phased lepidocrocite VOOH from single-shelled to double-shelled hollow nanospheres on the basis of programmed reaction-temperature strategy.

    Science.gov (United States)

    Wu, Changzheng; Zhang, Xiaodong; Ning, Bo; Yang, Jinlong; Xie, Yi

    2009-07-06

    Solid templates have been long regarded as one of the most promising ways to achieve single-shelled hollow nanostructures; however, few effective methods for the construction of multishelled hollow objects from their solid template counterparts have been developed. We report here, for the first time, a novel and convenient route to synthesizing double-shelled hollow spheres from the solid templates via programming the reaction-temperature procedures. The programmed temperature strategy developed in this work then provides an essential and general access to multishelled hollow nanostructures based on the designed extension of single-shelled hollow objects, independent of their outside contours, such as tubes, hollow spheres, and cubes. Starting from the V(OH)(2)NH(2) solid templates, we show that the relationship between the hollowing rate and the reaction temperature obey the Van't Hoff rule and Arrhenius activation-energy equation, revealing that it is the chemical reaction rather than the diffusion process that guided the whole hollowing process, despite the fact that the coupled reaction/diffusion process is involved in the hollowing process. Using the double-shelled hollow spheres as the PCM (CaCl(2).6H(2)O) matrix grants much better thermal-storage stability than that for the nanoparticles counterpart, revealing that the designed nanostructures can give rise to significant improvements for the energy-saving performance in future "smart house" systems.

  3. Thermal and mechanical stresses in a functionally graded thick sphere

    International Nuclear Information System (INIS)

    Eslami, M.R.; Babaei, M.H.; Poultangari, R.

    2005-01-01

    In this paper, a general solution for the one-dimensional steady-state thermal and mechanical stresses in a hollow thick sphere made of functionally graded material is presented. The temperature distribution is assumed to be a function of radius, with general thermal and mechanical boundary conditions on the inside and outside surfaces of the sphere. The material properties, except Poisson's ratio, are assumed to vary along the radius r according to a power law function. The analytical solution of the heat conduction equation and the Navier equation lead to the temperature profile, radial displacement, radial stress, and hoop stress as a function of radial direction

  4. Synthesis and superior lithium storage performances of hybrid hollow urchin-like silicate constructed by nanotubes wrapped in reduced graphene oxides

    International Nuclear Information System (INIS)

    Chen, Xuefang; Huang, Ying; Zhang, Kaichuang; Zhang, Xin; Wei, Chao

    2017-01-01

    Hybrid hollow urchin-like cobalt and copper silicate constructed by nanotubes encapsulated in graphene nanosheets composites were successfully prepared using graphene oxide as carrier and silica spheres as template, which were done through a well-known Stȍber process and a hydrothermal method. In fact, the synthesis of hybrid urchin-like silicate constructed by nanotubes through onestep hydrothermal reaction has rarely been reported.The electrochemical performances of the composites as lithium-ion battery anode materials were studiedfor the first time. As novel anode materials of Li-ion batteries, the special hollow urchin-like structure not only could facilitate the Li + diffusion and electron transport but alsocouldaccommodate the volume variation during the conversion reactions. In addition, the introduction of graphene can make the electrical conductivity better. Graphene wrapped hollow urchin-like silicate compositespossesses superior electrochemical cycling properties. The first discharge capacity is1955.2mAh/g with a current density of 300 mA/g. The unique well-designed configuration presents a beneficial method to synthesize efficient and high performance electrode materials for advanced power applications.

  5. Fabrication of Pt/Au concentric spheres from triblock copolymer.

    Science.gov (United States)

    Koh, Haeng-Deog; Park, Soojin; Russell, Thomas P

    2010-02-23

    Dispersion of an aqueous H(2)PtCl(6) solution into a trifluorotoluene (TFT) solution of a polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) triblock copolymer produced an emulsion-induced hollow micelle (EIHM), comprising a water nanodroplet stabilized by PEO, H(2)PtCl(6)/P2VP, and PS, sequentially. The following addition of an aqueous LiAuCl(4) solution into the dispersion led to a coordination of LiAuCl(4) and PEO. The resulting spherical EIHM structure was transformed to a hollow cylindrical micelle by the fusion of spherical EIHM with the addition of methanol. This structural transition was reversible by the alternative addition of methanol and TFT. Oxygen plasma was used to generate Pt/Au concentric spheres and hollow cylindrical Pt/Au nano-objects.

  6. Synthesis and characterization of hollow magnetic nanospheres modified with Au nanoparticles for bio-encapsulation

    Energy Technology Data Exchange (ETDEWEB)

    Seisno, Satoshi, E-mail: seino@mit.eng.osaka-u.ac.jp; Suga, Kent; Nakagawa, Takashi; Yamamoto, Takao A.

    2017-04-01

    Hollow magnetic nanospheres modified with Au nanoparticles were successfully synthesized. Au/SiO{sub 2} nanospheres fabricated by a radiochemical process were used as templates for ferrite templating. After the ferrite plating process, Au/SiO{sub 2} templates were fully coated with magnetite nanoparticles. Dissolution of the SiO{sub 2} core lead to the formation of hollow magnetic nanospheres with Au nanoparticles inside. The hollow magnetic nanospheres consisted of Fe{sub 3}O{sub 4} grains, with an average diameter of 60 nm, connected to form the sphere wall, inside which Au grains with an average diameter of 7.2 nm were encapsulated. The Au nanoparticles immobilized on the SiO{sub 2} templates contributed to the adsorption of the Fe ion precursor and/or Fe{sub 3}O{sub 4} seeds. These hollow magnetic nanospheres are proposed as a new type of nanocarrier, as the Au grains could specifically immobilize biomolecules inside the hollow sphere. - Highlights: • A procedure to synthesize hollow magnetic nanospheres with Au inside was reported. • The Au nanoparticles inside the hollow showed high Au-S binding affinity. • The nanospheres are expected to be suitable as a new magnetic carrier for DDS.

  7. A Powerful Public Sphere?

    DEFF Research Database (Denmark)

    Fiig, Christina

    The paper holds a critical discussion of the Habermasian model of the public sphere and proposes a revised model of a general public......The paper holds a critical discussion of the Habermasian model of the public sphere and proposes a revised model of a general public...

  8. Template-free synthesis and luminescent properties of hollow Ln:YOF (Ln = Eu or Er + Yb) microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Castro, E. [Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Americo Vespucio 49, Isla de La Cartuja, 41092 Sevilla (Spain); García-Sevillano, J.; Cussó, F. [Dpto. Física de Materiales, C-04, Universidad Autónoma de Madrid, Avda. Francisco Tomás y Valiente, 7, 28049 Madrid (Spain); Ocaña, M., E-mail: mjurado@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Americo Vespucio 49, Isla de La Cartuja, 41092 Sevilla (Spain)

    2015-01-15

    Highlights: • Hollow lanthanide doped YOF spheres have been synthesised through a template-free procedure. • Strong red emissions are observed for Eu-doped spheres under UV illumination. • Concentration quenching of luminescence takes place in the spheres at very high Eu doping levels. • Bright red emission is observed for Er, Yb codoped spheres, making this matrix advantageous for biomedical imaging. - Abstract: A method for the synthesis of hollow lanthanide doped yttrium oxyfluoride (YOF) spheres in the micrometer size range with cubic structure based on the pyrolysis at 600 °C of liquid aerosols generated from aqueous solutions containing the corresponding rare earth chlorides and trifluoroacetic acid has been developed. This procedure, which has been used for the first time for the synthesis of YFO based materials, is simpler and advantageous when compared with other methods usually employed for the production of hollow spheres since it does not require the use of sacrificial templates. In addition, it is continuous, which is desirable because of practical reasons. The procedure is also suitable for doping the YOF spheres with europium cations resulting in down converting red phosphors when activated with UV light, or for co-doping with both Er{sup 3+} and Yb{sup 3+} giving rise to up-converting phosphors, which emit intense red light under near infrared (NIR) irradiation. Because of their optical properties and hollow architecture, the developed materials may find applications in optoelectronic devices and biotechnology.

  9. Coprecipitation-assisted hydrothermal synthesis of PLZT hollow nanospheres

    International Nuclear Information System (INIS)

    Zhu, Renqiang; Zhu, Kongjun; Qiu, Jinhao; Bai, Lin; Ji, Hongli

    2010-01-01

    Lanthanum-modified lead zirconate titanate Pb 1-x La x (Zr 1-y Ti y )O 3 (PLZT) hollow nanospheres have been successfully prepared via a template-free hydrothermal method using the well-mixed coprecipitated precursors and the KOH mineralizer. The structure, composition, and morphology of the PLZT hollow nanospheres were characterized by XRD (X-ray diffraction), ICP (inductive coupled plasma emission spectrometer), FTIR (Fourier transform infrared spectra), TG/DTA (thermogravimetric analysis and differential thermal analysis), TEM (transmission electron microscopy) and SEAD (selected area diffraction). The results show that the composition and the morphology control of the PLZT products are determined by the KOH concentration. The PLZT hollow nanospheres with uniform size of about 4 nm were synthesized in the presence of 5 M KOH. The crystalline nanoparticles can be prepared at dilute KOH, in contrast to the amorphous powders prepared at concentrated KOH. Formation mechanisms of the PLZT hollow nanospheres are also discussed.

  10. Hollow-Core Fiber Lamp

    Science.gov (United States)

    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.

  11. The rising motion of spheres in structured fluids with yield stress

    Science.gov (United States)

    Mirzaagha, S.; Pasquino, R.; Iuliano, E.; D'Avino, G.; Zonfrilli, F.; Guida, V.; Grizzuti, N.

    2017-09-01

    The rising of spherical bodies in structured fluids with yield stress is studied. The system is a suspension of hydrogenated castor oil colloidal fibers in a surfactant micellar solution. The fiber network confers to the fluid a viscoelastic behavior, with a well-defined yield stress, which increases with increasing fiber concentration. Various fluids with different fiber contents are prepared and rheologically characterized. A home-made time-lapse photography setup is used to monitor the time evolution position of the spherical particles, and the rising motion of both hollow spheres and air bubbles, in the diameter range 65-550 μm, is measured. The experiments last as long as several weeks, corresponding to significantly low measured velocities. Finite element simulations are performed to support the experimental data, assuming both interfacial slip and no slip conditions. The fluid dynamic phenomenon is studied and discussed in terms of dimensionless numbers, such as yield ratio, Bingham number, and Stokes drag coefficient. The results are novel for the system (suspending medium and hollow spheres) and for the covered Bingham number range, which is extended over three orders of magnitude in comparison with already available literature results. Our values provide quantitative data of the mechanical properties (i.e., yield stress value) at very low shear rates, in a prohibitive range for a traditional rheometer, and agree with the macroscopic rheological response. Moreover, the important role of the power law index n of the Herschel-Bulkley model, used to fit the data, has been highlighted. Our results, based on a Bingham-like fluid, are compared with the experimental data already available with Carbopol, treated as a Herschel Bulkley fluid with n = 0.5. The results could have important implications in the fabric and personal care detergency, a technological area where many fluids have composition and show rheological properties similar to those considered in the

  12. Ultrathin 1T-phase MoS2 nanosheets decorated hollow carbon microspheres as highly efficient catalysts for solar energy harvesting and storage

    KAUST Repository

    Hsiao, Min-Chien

    2017-02-08

    The composite of MoS2 and hollow carbon sphere (MoS2@HCS) is prepared via a glucose-assisted one pot synthesis. The composite consists of hierarchical spheres with a diameter of 0.5–4 μm and these hollow spheres are decorated with a number of curled and interlaced MoS2 nanosheets. After the composite is subject to the lithium intercalation, the MoS2 is converted from 2H to 1T phase. In this current work, the activities of 1T-MoS2@HCS toward photocatalytic hydrogen evolution and the reduction of I3− in dye-sensitized solar cells (DSCs) are systemically investigated. When evaluated as the photocatalyst for hydrogen evolution, the amount of evolved hydrogen over 1T-MoS2@HCS can reach 143 μmol in 2 h, being 3.6 times higher than as-synthesized 2H-MoS2@HCS. Additionally, the 1T-MoS2@HCS can be employed as the counter electrode (CE) material in DSCs. The DSCs based on 1T-MoS2@HCS CE possesses the power conversion efficiency of 8.94%, being higher than that with 2H-MoS2@HCS CE (8.16%) and comparable to that with Pt CE (8.87%). Our study demonstrates that 1T-MoS2@HCS has a great potential as an inexpensive alternative to Pt catalysts.

  13. Ultrathin 1T-phase MoS2 nanosheets decorated hollow carbon microspheres as highly efficient catalysts for solar energy harvesting and storage

    KAUST Repository

    Hsiao, Min-Chien; Chang, Chin-Yu; Niu, Li-Juan; Bai, Feng; Li, Lain-Jong; Shen, Hsin-Hui; Lin, Jeng-Yu; Lin, Tsung-Wu

    2017-01-01

    The composite of MoS2 and hollow carbon sphere (MoS2@HCS) is prepared via a glucose-assisted one pot synthesis. The composite consists of hierarchical spheres with a diameter of 0.5–4 μm and these hollow spheres are decorated with a number of curled and interlaced MoS2 nanosheets. After the composite is subject to the lithium intercalation, the MoS2 is converted from 2H to 1T phase. In this current work, the activities of 1T-MoS2@HCS toward photocatalytic hydrogen evolution and the reduction of I3− in dye-sensitized solar cells (DSCs) are systemically investigated. When evaluated as the photocatalyst for hydrogen evolution, the amount of evolved hydrogen over 1T-MoS2@HCS can reach 143 μmol in 2 h, being 3.6 times higher than as-synthesized 2H-MoS2@HCS. Additionally, the 1T-MoS2@HCS can be employed as the counter electrode (CE) material in DSCs. The DSCs based on 1T-MoS2@HCS CE possesses the power conversion efficiency of 8.94%, being higher than that with 2H-MoS2@HCS CE (8.16%) and comparable to that with Pt CE (8.87%). Our study demonstrates that 1T-MoS2@HCS has a great potential as an inexpensive alternative to Pt catalysts.

  14. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Science.gov (United States)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  15. A facile one-pot hydrothermal method to prepare europium-doped titania hollow phosphors and their sensitized luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Feng Xuan; Yang Ling; Zhang Nianchun [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Western Huangpu Road, Guangzhou 510632 (China); Liu Yingliang, E-mail: tliuyl@jnu.edu.c [Department of Chemistry and Institute of Nanochemistry, Jinan University, 601 Western Huangpu Road, Guangzhou 510632 (China)

    2010-09-17

    Research highlights: {yields} The strongest emission intensity was observed with TiO{sub 2}:Eu{sub 0.2} hollow spheres and TiO{sub 2}:Eu{sub 0.2} hollow spheres calcining at 550 {sup o}C. Moreover, the strongest excitation of TiO{sub 2}:Eu{sub 0.2} hollow spheres transferred from 400 to 500 {sup o}C and the effective nonradiative energy transfer from the TiO{sub 2} hollow spheres host matrix to Eu{sup 3+} ions crystal field states was realized due to changes of crystalline field in the environment around Eu{sup 3+} ions occupying Ti{sup 4+} sites. The proposed energy transfer mechanism was that UV light is absorbed in the band of TiO{sub 2} hollow spheres crystal and then the energy is relaxed to the defect states of TiO{sub 2} host. The energy can transfer to the crystal states of Eu{sup 3+} ions ({sup 7}F{sub j}, j = 0, 1, 2, 3 and 4), which results in efficient photoluminescence. The fluorescent intensity of TiO{sub 2}:Eu{sub 0.2} hollow spheres was 2.2 times as strong as that of TiO{sub 2}:Eu{sub 0.2} bulk material. - Abstract: Monodisperse europium-activated titania hollow phosphors had been synthesized by a facile one-pot hydrothermal method using carbon spheres as hard templates. Samples were characterized by X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive spectrometer and photoluminescence spectrum. The strongest emission intensity was observed with TiO{sub 2}:Eu{sub 0.2} hollow spheres and TiO{sub 2}:Eu{sub 0.2} hollow spheres calcining at 550 {sup o}C. Moreover, the strongest excitation of TiO{sub 2}:Eu{sub 0.2} hollow spheres transferred from 400 to 500 {sup o}C and the effective nonradiative energy transfer from the TiO{sub 2} hollow spheres host matrix to Eu{sup 3+} ions crystal field states was realized due to changes of crystalline field in the environment around Eu{sup 3+} ions occupying Ti{sup 4+} sites. The proposed energy transfer mechanism was that UV light is absorbed in the band

  16. Experiment SPHERE status 2008

    International Nuclear Information System (INIS)

    Shaulov, S.B.; Besshapov, S.P.; Kabanova, N.V.; Sysoeva, T.I.; Antonov, R.A.; Anyuhina, A.M.; Bronvech, E.A.; Chernov, D.V.; Galkin, V.I.; Tkaczyk, W.; Finger, M.; Sonsky, M.

    2009-01-01

    The expedition carried out in March, 2008 to Lake Baikal became an important stage in the development of the SPHERE experiment. During the expedition the SPHERE-2 installation was hoisted, for the first time, on a tethered balloon, APA, to a height of 700 m over the lake surface covered with ice and snow. A series of test measurements were made. Preliminary results of the data processing are presented. The next plan of the SPHERE experiment is to begin a set of statistics for constructing the CR spectrum in the energy range 10 16 -10 18 eV.

  17. Experiment SPHERE status 2008

    Energy Technology Data Exchange (ETDEWEB)

    Shaulov, S.B., E-mail: shaul@sci.lebedev.r [P.N.Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prospect 53, Moscow 119991 (Russian Federation); Besshapov, S.P.; Kabanova, N.V.; Sysoeva, T.I. [P.N.Lebedev Physical Institute, Russian Academy of Sciences, Leninsky prospect 53, Moscow 119991 (Russian Federation); Antonov, R.A.; Anyuhina, A.M.; Bronvech, E.A.; Chernov, D.V.; Galkin, V.I. [Skobeltsyn Institute of Nuclear Physics, Lomonosov State University, Moscow 119992 (Russian Federation); Tkaczyk, W. [Department of Experimental Physics of University of Lodz (Poland); Finger, M. [Karlov University, Prague (Czech Republic); Sonsky, M. [COMPAS Consortium, Turnov (Czech Republic)

    2009-12-15

    The expedition carried out in March, 2008 to Lake Baikal became an important stage in the development of the SPHERE experiment. During the expedition the SPHERE-2 installation was hoisted, for the first time, on a tethered balloon, APA, to a height of 700 m over the lake surface covered with ice and snow. A series of test measurements were made. Preliminary results of the data processing are presented. The next plan of the SPHERE experiment is to begin a set of statistics for constructing the CR spectrum in the energy range 10{sup 16}-10{sup 18} eV.

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

    Science.gov (United States)

    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.

  19. Wet-Chemical Preparation of TiO2-Based Composites with Different Morphologies and Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Liqin Xiang

    2017-10-01

    Full Text Available TiO2-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO2 materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO2-based materials have been widely investigated in past decades. Based on our group’s research works on TiO2 materials, this review introduces several methods for the fabrication of TiO2, rare-earth-doped TiO2 and noble-metal-decorated TiO2 particles with different morphologies. We focused on the preparation and the formation mechanism of TiO2-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO2, noble metal nanoparticle-decorated 3D (three-dimensional urchin-like TiO2 and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO2 are briefly discussed.

  20. Scattering characteristics of relativistically moving concentrically layered spheres

    Science.gov (United States)

    Garner, Timothy J.; Lakhtakia, Akhlesh; Breakall, James K.; Bohren, Craig F.

    2018-02-01

    The energy extinction cross section of a concentrically layered sphere varies with velocity as the Doppler shift moves the spectral content of the incident signal in the sphere's co-moving inertial reference frame toward or away from resonances of the sphere. Computations for hollow gold nanospheres show that the energy extinction cross section is high when the Doppler shift moves the incident signal's spectral content in the co-moving frame near the wavelength of the sphere's localized surface plasmon resonance. The energy extinction cross section of a three-layer sphere consisting of an olivine-silicate core surrounded by a porous and a magnetite layer, which is used to explain extinction caused by interstellar dust, also depends strongly on velocity. For this sphere, computations show that the energy extinction cross section is high when the Doppler shift moves the spectral content of the incident signal near either of olivine-silicate's two localized surface phonon resonances at 9.7 μm and 18 μm.

  1. Synthesis of TCPP/ZnFe{sub 2}O{sub 4}@ZnO nanohollow sphere composite for degradation of methylene blue and 4-nitrophenol under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Rabbani, Mahboubeh, E-mail: m_rabani@iust.ac.ir; Heidari-Golafzani, Mahdi; Rahimi, Rahmatollah

    2016-08-15

    In this study, ZnFe{sub 2}O{sub 4} nanohallow spheres were synthesized by hydrothermal method, then ZnFe{sub 2}O{sub 4}@ZnO core-shell was prepared by forming of ZnO nanoshell onto magnetic microspheres via sol–gel route. Finally, TCPP/ZnFe{sub 2}O{sub 4}@ZnO composite was synthesized through the immobilization of the meso-tetrakis(4-carboxyphenyl)porphyrin on ZnFe{sub 2}O{sub 4}@ZnO core-shell. The prepared photocatalysts were characterized by different techniques such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), vibration sample magnetometery (VSM), Brunauer–Emmett–Teller (BET) model, UV–visible diffuse reflectance spectroscopy (DRS) and dynamic light scattering (DLS). The photocatalytic activity of prepared photocatalysts was evaluated for degradation of methylene blue, as an organic dye and 4-nitrophenol as an organic pollutant under visible LED light irradiation. The results illustrated that TCPP/ZnFe{sub 2}O{sub 4}@ZnO composite show better photodegradating behavior vs. methylene blue and 4-nitrophenol compared to ZnFe{sub 2}O{sub 4}@ZnO, pure ZnFe{sub 2}O{sub 4} and pure ZnO. - Highlights: • ZnFe{sub 2}O{sub 4} nanohallow spheres were synthesized by hydrothermal method. • ZnFe{sub 2}O{sub 4}@ZnO core-shell was prepared by forming of ZnO nanoshell. • ZnFe{sub 2}O{sub 4}@ZnO spheres was modified by immobilization of TCPP on their surface. • Photocatalytic activity of catalysts was tested for degradation of MB and 4-NP. • TCPP/ZnFe{sub 2}O{sub 4}@ZnO composite show better photodegradating behavior.

  2. The sphere-PAC fuel code 'SPHERE-3'

    International Nuclear Information System (INIS)

    Wallin, H.

    2000-01-01

    Sphere-PAC fuel is an advanced nuclear fuel, in which the cladding tube is filled with small fuel spheres instead of the more usual fuel pellets. At PSI, the irradiation behaviour of sphere-PAC fuel is calculated using the computer code SPHERE-3. The paper describes the present status of the SPHERE-3 code, and some results of the qualification process against experimental data. (author)

  3. The sphere-pac fuel code 'SPHERE-3'

    International Nuclear Information System (INIS)

    Wallin, H.; Nordstroem, L.A.; Hellwig, C.

    2001-01-01

    Sphere-pac fuel is an advanced nuclear fuel, in which the cladding tube is filled with small fuel spheres instead of the more usual fuel pellets. At PSI, the irradiation behaviour of sphere-pac fuel is calculated using the computer code SPHERE-3. The paper describes the present status of the SPHERE-3 code, and some results of the qualification process against experimental data. (author)

  4. Synthesis of CdS hollow/solid nanospheres and their chain-structures by membrane technique

    International Nuclear Information System (INIS)

    Duan Shumin; Wu Qingsheng; Jia Runping; Liu Xinbo

    2008-01-01

    CdS hollow/solid nanospheres and their chain-structures were successfully synthesized through supporting liquid membrane (SLM) system with bio-membrane. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy, and photoluminescence (PL) spectroscopy have been used for the characterization of the products. The average diameters of CdS solid/hollow spheres are about 10, 40 nm, respectively. The wall of the hollow spheres is about 5 nm. CdS products are all cubic face-centered structure with the cell constant a = 5.830 A. We also explore the morphology, structure and possible synthesis mechanism. A possible template mechanism has been proposed for the production of the hollow CdS nanocrystals, that is, CdS nanoparticles grow along the non-soakage interface between CHCl3 and reactant solution. During this process, the organic functional groups were crucial to the control of crystal morphologies

  5. Graphs with Eulerian unit spheres

    OpenAIRE

    Knill, Oliver

    2015-01-01

    d-spheres in graph theory are inductively defined as graphs for which all unit spheres S(x) are (d-1)-spheres and that the removal of one vertex renders the graph contractible. Eulerian d-spheres are geometric d-spheres which are d+1 colorable. We prove here that G is an Eulerian sphere if and only if the degrees of all the (d-2)-dimensional sub-simplices in G are even. This generalizes a Kempe-Heawood result for d=2 and is work related to the conjecture that all d-spheres have chromatic numb...

  6. Hollow bunches production

    CERN Document Server

    Hancock, S

    2017-01-01

    Hollow bunches address the issue of high-brightnessbeams suffering from transverse emittance growth in a strongspace charge regime. During the Proton Synchrotron (PS)injection plateau, the negative space charge tune shift canpush the beam onto theQy=6integer resonance. Modify-ing the longitudinal bunch profile in order to reduce the peakline charge density alleviates the detrimental impact of spacecharge. To this end we first produce longitudinally hollowphase space distributions in the PS Booster by exciting aparametric resonance with the phase loop feedback system.These inherently flat bunches are then transferred to the PS,where the beam becomes less prone to the emittance growthcaused by the integer resonance.During the late 2016 machine development sessions inthe PS Booster we profited from solved issues from 2015and managed to reliably extract hollow bunches of1.3eVsmatched longitudinal area. Furthermore, first results to cre-ate hollow bunches with larger longitudinal emittances to-wards the LHC Inject...

  7. Spinning the fuzzy sphere

    International Nuclear Information System (INIS)

    Berenstein, David; Dzienkowski, Eric; Lashof-Regas, Robin

    2015-01-01

    We construct various exact analytical solutions of the SO(3) BMN matrix model that correspond to rotating fuzzy spheres and rotating fuzzy tori. These are also solutions of Yang Mills theory compactified on a sphere times time and they are also translationally invariant solutions of the N=1"∗ field theory with a non-trivial charge density. The solutions we construct have a ℤ_N symmetry, where N is the rank of the matrices. After an appropriate ansatz, we reduce the problem to solving a set of polynomial equations in 2N real variables. These equations have a discrete set of solutions for each value of the angular momentum. We study the phase structure of the solutions for various values of N. Also the continuum limit where N→∞, where the problem reduces to finding periodic solutions of a set of coupled differential equations. We also study the topology change transition from the sphere to the torus.

  8. Controlled synthesis of ZnO hollow microspheres via precursor-template method and its gas sensing property

    International Nuclear Information System (INIS)

    Tian, Yu; Li, Jinchai; Xiong, Hui; Dai, Jiangnan

    2012-01-01

    Highlights: ► Zn powder as precursor template for synthesis ZnO hollow spheres. ► Different precursor templates result in different ZnO nanostructures. ► Different experimental conditions enable growth of different surface morphologies of ZnO sphere. ► ZnO hollow sphere materials have good gas sensing performance for detecting ethanol gas. - Abstract: Using Zn powder as precursor templates, ZnO hollow microspheres were successfully prepared by thermal evaporation method and characterized by X-ray diffraction analysis, scanning electron microscope and transmission electron microscope. It was found that different size and shape of precursor resulted in different ZnO nanostructures. When varying experimental conditions, such as air flow rate and working pressure, ZnO hollow spheres with different surface morphologies could be obtained. The advantages of the present synthetic technology are simple, relatively low cost, and high reproducibility. A gas sensor was fabricated from the as-prepared ZnO hollow microspheres and tested to the ethanol gas at different operating temperatures.

  9. Hollow Nanospheres Array Fabrication via Nano-Conglutination Technology.

    Science.gov (United States)

    Zhang, Man; Deng, Qiling; Xia, Liangping; Shi, Lifang; Cao, Axiu; Pang, Hui; Hu, Song

    2015-09-01

    Hollow nanospheres array is a special nanostructure with great applications in photonics, electronics and biochemistry. The nanofabrication technique with high resolution is crucial to nanosciences and nano-technology. This paper presents a novel nonconventional nano-conglutination technology combining polystyrenes spheres (PSs) self-assembly, conglutination and a lift-off process to fabricate the hollow nanospheres array with nanoholes. A self-assembly monolayer of PSs was stuck off from the quartz wafer by the thiol-ene adhesive material, and then the PSs was removed via a lift-off process and the hollow nanospheres embedded into the thiol-ene substrate was obtained. Thiolene polymer is a UV-curable material via "click chemistry" reaction at ambient conditions without the oxygen inhibition, which has excellent chemical and physical properties to be attractive as the adhesive material in nano-conglutination technology. Using the technique, a hollow nanospheres array with the nanoholes at the diameter of 200 nm embedded into the rigid thiol-ene substrate was fabricated, which has great potential to serve as a reaction container, catalyst and surface enhanced Raman scattering substrate.

  10. Fabrication and Characterization of Nanoenergetic Hollow Spherical Hexanitrostibene (HNS Derivatives

    Directory of Open Access Journals (Sweden)

    Xiong Cao

    2018-05-01

    Full Text Available The spherization of nanoenergetic materials is the best way to improve the sensitivity and increase loading densities and detonation properties for weapons and ammunition, but the preparation of spherical nanoenergetic materials with high regularization, uniform size and monodispersity is still a challenge. In this paper, nanoenergetic hollow spherical hexanitrostibene (HNS derivatives were fabricated via a one-pot copolymerization strategy, which is based on the reaction of HNS and piperazine in acetonitrile solution. Characterization results indicated the as-prepared reaction nanoenergetic products were HNS-derived oligomers, where a free radical copolymerization reaction process was inferred. The hollow sphere structure of the HNS derivatives was characterized by scanning electron microscopy (SEM, transmission electron microscope (TEM, and synchrotron radiation X-ray imaging technology. The properties of the nanoenergetic hollow spherical derivatives, including thermal decomposition and sensitivity are discussed in detail. Sensitivity studies showed that the nanoenergetic derivatives exhibited lower impact, friction and spark sensitivity than raw HNS. Thermogravimetric-differential scanning calorimeter (TG-DSC results showed that continuous exothermic decomposition occurred in the whole temperature range, which indicated that nanoenergetic derivatives have a unique role in thermal applications. Therefore, nanoenergetic hollow spherical HNS derivatives could provide a new way to modify the properties of certain energetic compounds and fabricate spherical nanomaterials to improve the charge configuration.

  11. Engineering Porous Polymer Hollow Fiber Microfluidic Reactors for Sustainable C-H Functionalization.

    Science.gov (United States)

    He, Yingxin; Rezaei, Fateme; Kapila, Shubhender; Rownaghi, Ali A

    2017-05-17

    Highly hydrophilic and solvent-stable porous polyamide-imide (PAI) hollow fibers were created by cross-linking of bare PAI hollow fibers with 3-aminopropyl trimethoxysilane (APS). The APS-grafted PAI hollow fibers were then functionalized with salicylic aldehyde for binding catalytically active Pd(II) ions through a covalent postmodification method. The catalytic activity of the composite hollow fiber microfluidic reactors (Pd(II) immobilized APS-grafted PAI hollow fibers) was tested via heterogeneous Heck coupling reaction of aryl halides under both batch and continuous-flow reactions in polar aprotic solvents at high temperature (120 °C) and low operating pressure. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) analyses of the starting and recycled composite hollow fibers indicated that the fibers contain very similar loadings of Pd(II), implying no degree of catalyst leaching from the hollow fibers during reaction. The composite hollow fiber microfluidic reactors showed long-term stability and strong control over the leaching of Pd species.

  12. Application of gel microsphere processes to preparation of Sphere-Pac nuclear fuel

    International Nuclear Information System (INIS)

    Haas, P.A.; Notz, K.J.; Spence, R.D.

    1978-01-01

    Sphere-Pac fabrication of nuclear fuels using two or more sizes of oxide or carbide spheres is ideally suited to nonproliferation-fuel cycles and remote refabrication. The sizes and compositions of spheres necessary for such fuel cycles have not been commonly prepared; therefore, modifications of sol-gel processes to meet these requirements are being developed and demonstrated

  13. ORGANIZATION IN CONTEMPORARY PUBLIC SPHERE

    Directory of Open Access Journals (Sweden)

    Rosemarie HAINES

    2013-12-01

    Full Text Available The critical analysis of Habermas’ Public Sphere Theory and the comparative undertaking to the current day enables us to assert that in contemporary society, public sphere is no longer a political public sphere, this dimension being completed by a societal dimension, the public sphere has extended and now we can talk about partial public spheres in an ever more commercial environment. The new rebuilding and communication technologies create a new type of public character: the visible sphere – non-located, non-dialogical and open. Information and communication are more and more involved in the restructuring of capitalism on an international scale and the reorganization of leadership and management systems. The reevaluation of the public sphere, public opinion, communication allows us to define public sphere according to the profound mutations from today’s democratic societies.

  14. Catalyst-free combined synthesis of Zn/ZnO core/shell hollow microspheres and metallic Zn microparticles by thermal evaporation and condensation route

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Waheed S. [Research Centre of Materials Science, Beijing Institute of Technology, Beijing 100081 (China); Cao Chuanbao, E-mail: cbcao@bit.edu.c [Research Centre of Materials Science, Beijing Institute of Technology, Beijing 100081 (China); Nabi, Ghulam; Yao Ruimin; Bhatti, Sajjad H. [Research Centre of Materials Science, Beijing Institute of Technology, Beijing 100081 (China)

    2010-09-17

    Research highlights: {yields} Catalyst-free combined synthesis of metal/semiconductor Zn/ZnO core/shell microspheres with hollow interiors on Si substrate and metallic Zn polygonal microparticles on glass substrate in a single experiment via thermal evaporation and condensation technique was reported. The Zn/ZnO hollow microspheres were observed to have dimensions in the range of 70-80 {mu}m whereas metallic Zn microparticles with polygonal cross section and oblate spherical shape were found to be of 8-10 {mu}m. Some of the Zn/ZnO core/shell hollow spheres were also observed to have single crystalline ZnO pointed rods in extremely low density grown on the outer shell. A vapor-liquid-solid (VLS) process based growth mechanism was proposed for the formation of Zn/ZnO core/shell microspheres with hollow interior. The optical properties of Zn/ZnO core/shell microspheres were investigated by measuring the photoluminescence (PL) spectra at room temperature (RT). Two very strong emission bands were observed at 373 and 469 nm in the ultraviolet and visible regions respectively under excitation wavelength of 325 nm. Also the effect of the various excitation wavelengths on the PL behaviour was studied at room temperature. PL studies of Zn/ZnO core/shell microspheres show the promise of the material for applications in UV and blue light optical devices. - Abstract: Here we report catalyst-free combined synthesis of metal/semiconductor Zn/ZnO core/shell microspheres with hollow interiors on Si substrate and metallic Zn polygonal microparticles on glass substrate in a single experiment via thermal evaporation and condensation technique using nitrogen (N{sub 2}) as carrier agent at 800 {sup o}C for 120 min. The Zn/ZnO hollow microspheres were observed to have dimensions in the range of 70-80 {mu}m whereas metallic Zn microparticles with polygonal cross section and oblate spherical shape were found to be of 8-10 {mu}m. Some of the Zn/ZnO core/shell hollow spheres were also

  15. High performance yttrium-doped BSCF hollow fibre membranes

    DEFF Research Database (Denmark)

    Haworth, P.; Smart, S.; Glasscock, Julie

    2012-01-01

    measurements in air was similar for both compositions, suggesting that the higher oxygen fluxes obtained for BSCFY hollow fibres could be attributed to the higher non-stoichiometry due to yttrium addition to the BSCF crystal structure. In addition, the improvement of oxygen fluxes for small wall thickness (∼0...

  16. Permeation of supercritical carbon dioxide through polymeric hollow fiber membranes

    NARCIS (Netherlands)

    Patil, V.E.; Broeke, van den L.J.P.; Vercauteren, F.F.; Keurentjes, J.T.F.

    2006-01-01

    Permeation of carbon dioxide was measured for two types of composite polymeric hollow fiber membranes for feed pressures up to 18 MPa at a temp. of 313 K. support membrane. The membranes consist of a polyamide copolymer (IPC) layer or a poly(vinyl alc.) (PVA) layer on top of a polyethersulfone

  17. Specific surface area of overlapping spheres in the presence of obstructions.

    Science.gov (United States)

    Jenkins, D R

    2013-02-21

    This study considers the random placement of uniform sized spheres, which may overlap, in the presence of another set of randomly placed (hard) spheres, which do not overlap. The overlapping spheres do not intersect the hard spheres. It is shown that the specific surface area of the collection of overlapping spheres is affected by the hard spheres, such that there is a minimum in the specific surface area as a function of the relative size of the two sets of spheres. The occurrence of the minimum is explained in terms of the break-up of pore connectivity. The configuration can be considered to be a simple model of the structure of a porous composite material. In particular, the overlapping particles represent voids while the hard particles represent fillers. Example materials are pervious concrete, metallurgical coke, ice cream, and polymer composites. We also show how the material properties of such composites are affected by the void structure.

  18. Fabrication of silica hollow particles using yeast cells as a template

    Science.gov (United States)

    Liao, Shenglan; Lin, Liqin; Chen, Xiaofang; Liu, Jingru; Zhang, Biao

    2018-04-01

    Inorganic hollow particles have attracted great interest in recent years. In this study, silica micro spheres were produced. Yeast cells were used as a biological template. The silica shell was synthesized by the hydrolysis of tetraethoxysilane (TEOS) in water-alcohol mixtures as solvent using ammonia as a catalyst according to the Stoeber process. Various approaches including X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transformed infrared (FT-IR) spectroscopy were used to characterize the products. The results showed that the thermally treated samples were SiO2 hollow microspheres with a diameter varying between 1-5μm.

  19. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... applications, and places emphasis on the development of polarization maintaining (PM) HC-PCF. The polarization cross-coupling characteristics of PM HC-PCF are very different from those of conventional PM fibers. The former fibers have the advantage of suffering far less from stress-field fluctuations...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  20. VMware vSphere Design

    CERN Document Server

    Guthrie, Forbes; Saidel-Keesing, Maish

    2011-01-01

    The only book focused on designing VMware vSphere implementations.VMware vSphere is the most widely deployed virtualization platform today. Considered the most robust and sophisticated hypervisor product, vSphere is the de facto standard for businesses, both large and small. This book is the only one of its kind to concisely explain how to execute a successful vSphere architecture, tailored to meet your company's needs. Expert authors share with you the factors that shape the design of a vSphere implementation. Learn how to make the right design decisions for your environment.Explores the late

  1. Method for sizing hollow microspheres

    Science.gov (United States)

    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.

  2. Mercury's Hollows: New Information on Distribution and Morphology from MESSENGER Observations at Low Altitude

    Science.gov (United States)

    Blewett, D. T.; Stadermann, A. C.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.; Peplowski, P. N.

    2014-12-01

    MESSENGER's orbital mission at Mercury led to the discovery of an unusual landform not known from other airless rocky bodies of the Solar System. Hollows are irregularly shaped, shallow, rimless depressions, often occurring in clusters and with high-reflectance interiors and halos. The fresh appearance of hollows suggests that they are relatively young features. For example, hollows are uncratered, and talus aprons downslope of hollows in certain cases appear to be covering small impact craters (100-200 in diameter). Hence, some hollows may be actively forming at present. The characteristics of hollows are suggestive of formation via destruction of a volatile-bearing phase (possibly one or more sulfides) through solar heating, micrometeoroid bombardment, and/or ion impact. Previous analysis showed that hollows are associated with low-reflectance material (LRM), a color unit identified from global color images. The material hosting hollows has often been excavated from depth by basin or crater impacts. Hollows are small features (tens of meters to several kilometers), so their detection and characterization with MESSENGER's global maps have been limited. MESSENGER's low-altitude orbits provide opportunities for collection of images at high spatial resolutions, which reveal new occurrences of hollows and offer views of hollows with unprecedented detail. As of this writing, we have examined more than 21,000 images with pixel sizes Shadow-length measurements were made on 280 images, yielding the depths of 1343 individual hollows. The mean depth is 30 m, with a standard deviation of 17 m. We also explored correlations between the geographic locations of hollows and maps provided by the MESSENGER geochemical sensors (X-Ray, Gamma-Ray, and Neutron Spectrometers), including the abundances of Al/Si, Ca/Si, Fe/Si, K, Mg/Si, and S/Si, as well as total neutron cross-section. No clear compositional trends emerged; it is likely that any true compositional preference for terrain

  3. Fabrication of Polyacrylonitrile Hollow Fiber Membranes from Ionic Liquid Solutions

    KAUST Repository

    Kim, Dooli; Moreno Chaparro, Nicolas; Nunes, Suzana Pereira

    2015-01-01

    The interest in green processes and products has increased to reduce the negative impact of many industrial processes to the environment. Solvents, which play a crucial role in the fabrication of membranes, need to be replaced by sustainable and less toxic solvent alternatives for commonly used polymers. The purpose of this study is the fabrication of greener hollow fiber membranes based on polyacrylonitrile (PAN), substituting dimethylformamide (DMF) by less toxic mixtures of ionic liquids (IL) and dimethylsulfoxide (DMSO). A thermodynamic analysis was conducted, estimating the Gibbs free energy of mixing to find the most convenient solution compositions. Hollow fiber membranes were manufactured and optimized. As a result, a uniform pattern and high porosity were observed in the inner surface of the membranes prepared from the ionic liquid solutions. The membranes were coated with a polyamide layer by interfacial polymerization the hollow fiber membranes were applied in forward osmosis experiments by using sucrose solutions as draw solution.

  4. Fabrication of Polyacrylonitrile Hollow Fiber Membranes from Ionic Liquid Solutions

    KAUST Repository

    Kim, Dooli

    2015-10-08

    The interest in green processes and products has increased to reduce the negative impact of many industrial processes to the environment. Solvents, which play a crucial role in the fabrication of membranes, need to be replaced by sustainable and less toxic solvent alternatives for commonly used polymers. The purpose of this study is the fabrication of greener hollow fiber membranes based on polyacrylonitrile (PAN), substituting dimethylformamide (DMF) by less toxic mixtures of ionic liquids (IL) and dimethylsulfoxide (DMSO). A thermodynamic analysis was conducted, estimating the Gibbs free energy of mixing to find the most convenient solution compositions. Hollow fiber membranes were manufactured and optimized. As a result, a uniform pattern and high porosity were observed in the inner surface of the membranes prepared from the ionic liquid solutions. The membranes were coated with a polyamide layer by interfacial polymerization the hollow fiber membranes were applied in forward osmosis experiments by using sucrose solutions as draw solution.

  5. Beyond fuzzy spheres

    International Nuclear Information System (INIS)

    Govindarajan, T R; Padmanabhan, Pramod; Shreecharan, T

    2010-01-01

    We study polynomial deformations of the fuzzy sphere, specifically given by the cubic or the Higgs algebra. We derive the Higgs algebra by quantizing the Poisson structure on a surface in R 3 . We find that several surfaces, differing by constants, are described by the Higgs algebra at the fuzzy level. Some of these surfaces have a singularity and we overcome this by quantizing this manifold using coherent states for this nonlinear algebra. This is seen in the measure constructed from these coherent states. We also find the star product for this non-commutative algebra as a first step in constructing field theories on such fuzzy spaces.

  6. Falling-sphere radioactive viscometry

    International Nuclear Information System (INIS)

    Souza, R. de.

    1987-01-01

    In this work the falling sphere viscometric method was studies experimentally using a sphere tagged with 198 Au radiosotopo, the objective being the demosntration of the advantages of this technique in relation to the traditional method. The utilisation of the falling radioactive sphere permits the point-point monitoring of sphere position as a function of count rate. The fall tube wall and end effects were determined by this technique. Tests were performed with spheres of different diameters in four tubes. The application of this technique demosntrated the wall and end effects in sphere speed. The case of sphere fall in the steady slow regime allowed the determination of the terminal velocity, showing the increase of botton end effect as the sphere approaches the tube base. In the case the transient slow regime, the sphere was initially in a state of respose near the top surface. The data obtained show the influence of the free surface and wall on the sphere acceleration. These experimental data were applied to the Basset equation on order to verify the behaviour of the terms in this equation. (author) [pt

  7. Simultaneous chemical modification and structural transformation of Stöber silica spheres for integration of nanocatalysts

    KAUST Repository

    Yao, Kexin; Zeng, Huachun

    2012-01-01

    ) hollow spheres, on which zinc oxide (ZnO) phase and ruthenium (Ru) nanoparticles have been deposited and assembled sequentially in solution phase. A series of complex Ru/ZnO/Zn-SiO 2 nanocatalysts has been thus been integrated onto the zinc-doped SiO 2

  8. Dual layer hollow fiber sorbents for trace H2S removal from gas streams

    KAUST Repository

    Bhandari, Dhaval A.; Bessho, Naoki; Koros, William J.

    2013-01-01

    Hollow fiber sorbents are pseudo monolithic materials with potential use in various adsorption based applications. Dual layer hollow fiber sorbents have the potential to allow thermal regeneration without direct contact of the regeneration fluid with the sorbent particles. This paper considers the application of dual layer hollow fiber sorbents for a case involving trace amounts of H2S removal from a simulated gas stream and offers a comparison with single layer hollow fiber sorbents. The effect of spin dope composition and core layer zeolite loading on the gas flux, H2S transient sorption capacity and pore structure are also studied. This work can be used as a guide to develop and optimize dual layer hollow fiber sorbent properties beyond the specific example considered here. © 2013 Elsevier Ltd.

  9. Dual layer hollow fiber sorbents for trace H2S removal from gas streams

    KAUST Repository

    Bhandari, Dhaval A.

    2013-05-01

    Hollow fiber sorbents are pseudo monolithic materials with potential use in various adsorption based applications. Dual layer hollow fiber sorbents have the potential to allow thermal regeneration without direct contact of the regeneration fluid with the sorbent particles. This paper considers the application of dual layer hollow fiber sorbents for a case involving trace amounts of H2S removal from a simulated gas stream and offers a comparison with single layer hollow fiber sorbents. The effect of spin dope composition and core layer zeolite loading on the gas flux, H2S transient sorption capacity and pore structure are also studied. This work can be used as a guide to develop and optimize dual layer hollow fiber sorbent properties beyond the specific example considered here. © 2013 Elsevier Ltd.

  10. Analytic functionals on the sphere

    CERN Document Server

    Morimoto, Mitsuo

    1998-01-01

    This book treats spherical harmonic expansion of real analytic functions and hyperfunctions on the sphere. Because a one-dimensional sphere is a circle, the simplest example of the theory is that of Fourier series of periodic functions. The author first introduces a system of complex neighborhoods of the sphere by means of the Lie norm. He then studies holomorphic functions and analytic functionals on the complex sphere. In the one-dimensional case, this corresponds to the study of holomorphic functions and analytic functionals on the annular set in the complex plane, relying on the Laurent series expansion. In this volume, it is shown that the same idea still works in a higher-dimensional sphere. The Fourier-Borel transformation of analytic functionals on the sphere is also examined; the eigenfunction of the Laplacian can be studied in this way.

  11. Synthesis and characterization of hollow V2O5 microspheres for supercapacitor electrode with pseudocapacitance

    Directory of Open Access Journals (Sweden)

    Zhang Yifu

    2017-02-01

    Full Text Available Hollow V2O5 microspheres (HVOM were fabricated using NH4VO3, ethylene glycol and carbon spheres as the starting materials by a template solvothermal approach and subsequent calcination. The morphology and composition were characterized by field emission scanning electron microscopy (FE-SEM, X-ray powder diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR and Brunauer-Emmet-Teller (BET. The results showed that the obtained HVOM were constructed from nanoparticles with rough surface. The electrochemical properties of HVOM as a supercapacitor electrode were investigated by cyclic voltammetry (CV and galvanostatic charge-discharge (GCD. HVOM displayed excellent pseudocapacitance property and their specific capacitances were 488 F·g–1, 455 F·g–1, 434 F·g–1 and 396 F·g–1 at the current density of 0.5 A·g–1, 1 A·g–1, 2 A·g–1 and 5 A·g–1, respectively. They also exhibited an excellent energy density of 8.784 × 105 J·kg–1 at a power density of 900 W·kg–1 . The good electrochemical properties of the as-synthesized HVOM make them a promising candidate as a cathode material for supercapacitors.

  12. Hierarchical CuO hollow microspheres: Controlled synthesis for enhanced lithium storage performance

    International Nuclear Information System (INIS)

    Guan Xiangfeng; Li Liping; Li Guangshe; Fu Zhengwei; Zheng Jing; Yan Tingjiang

    2011-01-01

    Graphical abstract: Hierarchical CuO microspheres with hollow interiors were formed through self-wrapping of a single layer of radically oriented CuO nanorods, and these microspheres showed excellent cycle performance and enhanced lithium storage capacity. Display Omitted Research highlights: → Hierarchical CuO hollow microspheres were prepared by a hydrothermal method. → The CuO hollow microspheres were assembled from radically oriented nanorods. → The growth mechanism was proposed to proceed via self-assembly and Ostwald's ripening. → The microspheres showed good cycle performance and enhanced lithium storage capacity. → Hierarchical microstructures with hollow interiors promote electrochemical property. - Abstract: In this work, hierarchical CuO hollow microspheres were hydrothermally prepared without use of any surfactants or templates. By controlling the formation reaction conditions and monitoring the relevant reaction processes using time-dependent experiments, it is demonstrated that hierarchical CuO microspheres with hollow interiors were formed through self-wrapping of a single layer of radically oriented CuO nanorods, and that hierarchical spheres could be tuned to show different morphologies and microstructures. As a consequence, the formation mechanism was proposed to proceed via a combined process of self-assembly and Ostwald's ripening. Further, these hollow microspheres were initiated as the anode material in lithium ion batteries, which showed excellent cycle performance and enhanced lithium storage capacity, most likely because of the synergetic effect of small diffusion lengths in building blocks of nanorods and proper void space that buffers the volume expansion. The strategy reported in this work is reproducible, which may help to significantly improve the electrochemical performance of transition metal oxide-based anode materials via designing the hollow structures necessary for developing lithium ion batteries and the relevant

  13. An ultrasensitive hollow-silica-based biosensor for pathogenic Escherichia coli DNA detection.

    Science.gov (United States)

    Ariffin, Eda Yuhana; Lee, Yook Heng; Futra, Dedi; Tan, Ling Ling; Karim, Nurul Huda Abd; Ibrahim, Nik Nuraznida Nik; Ahmad, Asmat

    2018-03-01

    A novel electrochemical DNA biosensor for ultrasensitive and selective quantitation of Escherichia coli DNA based on aminated hollow silica spheres (HSiSs) has been successfully developed. The HSiSs were synthesized with facile sonication and heating techniques. The HSiSs have an inner and an outer surface for DNA immobilization sites after they have been functionalized with 3-aminopropyltriethoxysilane. From field emission scanning electron microscopy images, the presence of pores was confirmed in the functionalized HSiSs. Furthermore, Brunauer-Emmett-Teller (BET) analysis indicated that the HSiSs have four times more surface area than silica spheres that have no pores. These aminated HSiSs were deposited onto a screen-printed carbon paste electrode containing a layer of gold nanoparticles (AuNPs) to form a AuNP/HSiS hybrid sensor membrane matrix. Aminated DNA probes were grafted onto the AuNP/HSiS-modified screen-printed electrode via imine covalent bonds with use of glutaraldehyde cross-linker. The DNA hybridization reaction was studied by differential pulse voltammetry using an anthraquinone redox intercalator as the electroactive DNA hybridization label. The DNA biosensor demonstrated a linear response over a wide target sequence concentration range of 1.0×10 -12 -1.0×10 -2 μM, with a low detection limit of 8.17×10 -14 μM (R 2 = 0.99). The improved performance of the DNA biosensor appeared to be due to the hollow structure and rough surface morphology of the hollow silica particles, which greatly increased the total binding surface area for high DNA loading capacity. The HSiSs also facilitated molecule diffusion through the silica hollow structure, and substantially improved the overall DNA hybridization assay. Graphical abstract Step-by-step DNA biosensor fabrication based on aminated hollow silica spheres.

  14. Preparation of Nickel Cobalt Sulfide Hollow Nanocolloids with Enhanced Electrochemical Property for Supercapacitors Application

    Science.gov (United States)

    Chen, Zhenhua; Wan, Zhanghui; Yang, Tiezhu; Zhao, Mengen; Lv, Xinyan; Wang, Hao; Ren, Xiuli; Mei, Xifan

    2016-01-01

    Nanostructured functional materials with hollow interiors are considered to be good candidates for a variety of advanced applications. However, synthesis of uniform hollow nanocolloids with porous texture via wet chemistry method is still challenging. In this work, nickel cobalt precursors (NCP) in sub-micron sized spheres have been synthesized by a facile solvothermal method. The subsequent sulfurization process in hydrothermal system has changed the NCP to nickel cobalt sulfide (NCS) with porous texture. Importantly, the hollow interiors can be tuned through the sulfurization process by employing different dosage of sulfur source. The derived NCS products have been fabricated into supercapacitor electrodes and their electrochemical performances are measured and compared, where promising results were found for the next-generation high-performance electrochemical capacitors. PMID:27114165

  15. Synthesis and Characterization of Gd2O3 Hollow Microspheres Using a Template-Directed Method

    Directory of Open Access Journals (Sweden)

    Xueliang Jiang

    2016-04-01

    Full Text Available Uniform rare-earth gadolinium oxide (Gd2O3 hollow microspheres, as formed through a urea-assisted homogenous precipitation process using carbon spheres as a template and a subsequent heat treatment, were characterized by using X-ray diffraction, Fourier transformed infared spectroscopy, thermogravimetry, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Tellet surface area measurement. The results indicate that the final products can be indexed to a cubic Gd2O3 phase with high purity and have a uniform morphology at 500 nm in diameter and 20 nm in shell thickness. The as-synthesized Gd2O3 hollow microspheres exhibited a superior photooxidation activity to that of Gd2O3 powder and an effect similar to P25, significantly broadening the potential of Gd2O3 hollow microspheres for many practical applications.

  16. Surfactant-assisted solvothermal preparation of submicrometer-sized hollow hematite particles and their photocatalytic activity

    International Nuclear Information System (INIS)

    Lian Suoyuan; Wang Enbo; Gao Lei; Wu Di; Song Yanli; Xu Lin

    2006-01-01

    Submicrometer-sized hollow hematite particles were prepared through a surfactant-assisted solvothermal process. The amount of FeCl 3 .H 2 O and cetyltrimethylammonium bromide, and the acidity of the solution were systematically altered to study their effects on the final results. Hollow hematite particles with shapes from sphere, ellipsoid to peanut were obtained. Their sizes range from 500 nm to 2 μm with shell thickness from 100 to 500 nm. Powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction were applied to investigate the products' crystallinity, purity, morphology, size and structural features. Finally, the study on the photocatalysis of Fe 2 O 3 for the destruction of diethyl phthalate in water was carried out. The result proved that Fe 2 O 3 hollow particles were effective photocatalysts for the degradation of DEP, with 96.8% destruction ratio being obtained within 60 min

  17. Interconnected Silicon Hollow Nanospheres for Lithium-Ion Battery Anodes with Long Cycle Life

    KAUST Repository

    Yao, Yan

    2011-07-13

    Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g-1 with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure. © 2011 American Chemical Society.

  18. Pele's tears and spheres

    Science.gov (United States)

    Porritt, L. A.; Quane, S.; Russell, K.

    2011-12-01

    Pele's tears are a well known curiosity commonly associated with low viscosity basaltic explosive eruptions. However, these pyroclasts are rarely studied in detail and there is no full explanation for their formation. These intriguing pyroclasts have smooth glassy surfaces, vesiculated interiors, and fluidal morphologies tending towards droplets and then spheres as they decrease in size to Pele's tears from the 1959 fire-fountaining eruption of Kilauea Iki involving size and density measurements. Using thin section and SEM analysis we also consider their internal and external morphologies, porosity and bubble size distributions, and surface textures. Finally we consider the mechanisms of magma fragmentation, timescales of relaxation, and cooling rates that are responsible for their formation.

  19. Panoramic stereo sphere vision

    Science.gov (United States)

    Feng, Weijia; Zhang, Baofeng; Röning, Juha; Zong, Xiaoning; Yi, Tian

    2013-01-01

    Conventional stereo vision systems have a small field of view (FOV) which limits their usefulness for certain applications. While panorama vision is able to "see" in all directions of the observation space, scene depth information is missed because of the mapping from 3D reference coordinates to 2D panoramic image. In this paper, we present an innovative vision system which builds by a special combined fish-eye lenses module, and is capable of producing 3D coordinate information from the whole global observation space and acquiring no blind area 360°×360° panoramic image simultaneously just using single vision equipment with one time static shooting. It is called Panoramic Stereo Sphere Vision (PSSV). We proposed the geometric model, mathematic model and parameters calibration method in this paper. Specifically, video surveillance, robotic autonomous navigation, virtual reality, driving assistance, multiple maneuvering target tracking, automatic mapping of environments and attitude estimation are some of the applications which will benefit from PSSV.

  20. Switching a Nanocluster Core from Hollow to Non-hollow

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2016-03-24

    Modulating the structure-property relationship in atomically precise nanoclusters (NCs) is vital for developing novel NC materials and advancing their applications. While promising biphasic ligand-exchange (LE) strategies have been developed primarily to attain novel NCs, understanding the mechanistic aspects involved in tuning the core and the ligand-shell of NCs in such biphasic processes is challenging. Here, we design a single phase LE process that enabled us to elucidate the mechanism of how a hollow NC (e.g., [Ag44(SR)30]4-, -SR: thiolate) converts into a non-hollow NC (e.g., [Ag25(SR)18]-), and vice versa. Our study reveals that the complete LE of the hollow [Ag44(SPhF)30]4- NCs (–SPhF: 4-fluorobenzenethiolate) with incoming 2,4-dimethylbenzenethiol (HSPhMe2) induced distortions in the Ag44 structure forming the non-hollow [Ag25(SPhMe2)18]- by a disproportionation mechanism. While the reverse reaction of [Ag25(SPhMe2)18]- with HSPhF prompted an unusual dimerization of Ag25, followed by a rearrangement step that reproduces the original [Ag44(SPhF)30]4-. Remarkably, both the forward and the backward reactions proceed through similar size intermediates that seem to be governed by the boundary conditions set by the thermodynamic and electronic stability of the hollow and non-hollow metal cores. Furthermore, the resizing of NCs highlights the surprisingly long-range effect of the ligands which are felt by atoms far deep in the metal core, thus opening a new path for controlling the structural evolution of nanoparticles.

  1. Synthesis and Characterization of Hollow Magnetic Alloy (GdNi2, Co5Gd Nanospheres Coated with Gd2O3

    Directory of Open Access Journals (Sweden)

    Wang Li

    2014-01-01

    Full Text Available Uniform magnetic hollow nanospheres (GdNi2, Co5Gd coated with Gd2O3 have been successfully prepared on a large scale via a urea-based homogeneous precipitation method using silica (SiO2 spheres as sacrificed templates, followed by subsequent heat treatment. Nitrogen sorption measurements and scanning electron microscope reveal that these hollow-structured magnetic nanospheres have the mesoporous shells that are composed of a large amount of uniform nanoparticles. After reduction treatment, these nanoparticles exhibit superparamagnetism that might have potential applications in medicine. Furthermore, the developed synthesis route may provide an important guidance for the preparation of other multifunctional hollow spherical materials.

  2. The Riddle of the Apparently Hollow Himalaya

    Indian Academy of Sciences (India)

    The Riddle of the Apparently Hollow Himalaya. Ramesh .... It was as if the Himalayas were hollow inside. ... block would be consistent with the ground elevation in such a ... Alternative models and possible preference: Many refinements of.

  3. Determination of elastic modulus for hollow spherical shells via resonant ultrasound spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiaojun [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Xing; Wang, Zongwei [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Chen, Qian; Qian, Menglu [Institute of Acoustic, Tongji University, Shanghai 200092 (China); Meng, Jie [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Yongjian [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Shen, Hao [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Gao, Dangzhong, E-mail: dgaocn@163.com [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)

    2017-04-15

    Highlights: • The axisymmetric frequency equation of an isotropic hollow two-layer sphere is deduced by three dimension elasticity theory and global matrix method. • The simulated results demonstrate that the natural frequencies of a hollow sphere are more strongly dependent on Young’s modulus than Poisson's ratio. • The Young’s moduli of polymer capsules with an sub-millimeter inner radius are measured accurately with an uncertainty of ∼10%. - Abstract: The elastic property of a capsule is one of the essential parameters both in engineering applications and scientific understanding of material nature in inertial confinement fusion (ICF) experiments. The axisymmetric frequency equation of an isotropic hollow two-layer sphere is deduced by three dimension elasticity theory and global matrix method, and a combined resonant ultrasound spectroscopy(RUS), which consists of a piezoelectric-based resonant ultrasound spectroscopy(PZT-RUS) and a laser-based resonant ultrasound spectroscopy(LRUS), is developed for determining the elastic modulus of capsule. To understand the behavior of natural frequencies varying with elastic properties, the dependence of natural frequencies on Young’s modulus and Poisson’s ratio are calculated numerically. Some representative polymer capsules are measured using PZT-RUS and LRUS. Based on the theoretical and experimental results, the Young’s moduli of these capsules are measured accurately with an uncertainty of ∼10%.

  4. Spherical Approximation on Unit Sphere

    Directory of Open Access Journals (Sweden)

    Eman Samir Bhaya

    2018-01-01

    Full Text Available In this paper we introduce a Jackson type theorem for functions in LP spaces on sphere And study on best approximation of  functions in  spaces defined on unit sphere. our central problem is to describe the approximation behavior of functions in    spaces for  by modulus of smoothness of functions.

  5. Hollow nanotubular toroidal polymer microrings.

    Science.gov (United States)

    Lee, Jiyeong; Baek, Kangkyun; Kim, Myungjin; Yun, Gyeongwon; Ko, Young Ho; Lee, Nam-Suk; Hwang, Ilha; Kim, Jeehong; Natarajan, Ramalingam; Park, Chan Gyung; Sung, Wokyung; Kim, Kimoon

    2014-02-01

    Despite the remarkable progress made in the self-assembly of nano- and microscale architectures with well-defined sizes and shapes, a self-organization-based synthesis of hollow toroids has, so far, proved to be elusive. Here, we report the synthesis of polymer microrings made from rectangular, flat and rigid-core monomers with anisotropically predisposed alkene groups, which are crosslinked with each other by dithiol linkers using thiol-ene photopolymerization. The resulting hollow toroidal structures are shape-persistent and mechanically robust in solution. In addition, their size can be tuned by controlling the initial monomer concentrations, an observation that is supported by a theoretical analysis. These hollow microrings can encapsulate guest molecules in the intratoroidal nanospace, and their peripheries can act as templates for circular arrays of metal nanoparticles.

  6. Hollow fiber liquid supported membranes

    International Nuclear Information System (INIS)

    Violante, V.

    1987-01-01

    The hollow fiber system are well known and developed in the scientific literature because of their applicability in the process separation units. The authors approach to a mathematical model for a particular hollow fiber system, usin liquid membranes. The model has been developed in order to obtain a suitable tool for a sensitivy analysis and for a scaling-up. This kind of investigation is very usefull from an engineering point of view, to get a spread range of information to build up a pilot plant from the laboratory scale

  7. Adsorption and magnetic removal of neutral red dye from aqueous solution using Fe3O4 hollow nanospheres

    International Nuclear Information System (INIS)

    Iram, Mahmood; Guo, Chen; Guan Yueping; Ishfaq, Ahmad; Liu Huizhou

    2010-01-01

    Fe 3 O 4 hollow nanospheres were prepared via a simple one-pot template-free hydrothermal method and were fully characterized. These magnetic spheres have been investigated for application as an adsorbant for the removal of dye contaminants from water. Because of the high specific surface area, nano-scale particle size, and hollow porous material, Fe 3 O 4 hollow spheres showed favorable adsorption behavior for Neutral red. Factors affecting adsorption, such as, initial dye concentration, pH and contact time were evaluated. Langmuir and the Freundlich adsorption isotherms were selected to explicate the interaction of the dye and magnetic adsorbant. The characteristic parameters for each isotherm have been determined. The overall trend followed an increase of the sorption capacity with increasing dye concentration with a maximum of 90% dye removal. The monolayer adsorption capacity of magnetic hollow spheres (0.05 g) for NR in the concentration range studied, as calculated from the Langmuir isotherm model at 25 deg. C and pH 6, was found to be 105 mg g -1 . Adsorption kinetic followed pseudo-second-order reaction kinetics. Thermodynamic study showed that the adsorption processes are spontaneous and endothermic. The combination of the superior adsorption and the magnetic properties of Fe 3 O 4 nanospheres can be useful as a powerful separation tool to deal with environmental pollution.

  8. Preparation and crystallization of hollow α-Fe2O3 microspheres following the gas-bubble template method

    International Nuclear Information System (INIS)

    Valladares, L. de los Santos; León Félix, L.; Espinoza Suarez, S.M.; Bustamante Dominguez, A.G.; Mitrelias, T.; Holmes, S.; Moreno, N.O.; Albino Aguiar, J.; Barnes, C.H.W.

    2016-01-01

    In this work we report the formation of hollow α-Fe 2 O 3 (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO 3 ) 3 .9H 2 O and citric acid in water by sol–gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250–400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. - Highlights: • Formation of hollow hematite microspheres by the gas-bubble template method. • This technique does not require hard templates or special conditions of atmosphere. • Annealing promotes the transition magnetite to maghemite to hematite. • Crystallization of the hematite shells increase with annealing temperature.

  9. Sputter deposition of BSCCO films from a hollow cathode

    International Nuclear Information System (INIS)

    Lanagan, M.T.; Kampwirth, R.T.; Doyle, K.; Kowalski, S.; Miller, D.; Gray, K.E.

    1991-01-01

    High-T c superconducting thin films were deposited onto MgO single crystal substrates from a hollow cathode onto ceramic targets with the nominal composition of Bi 2 Sr 2 CaCu 2 O x . Films similar in composition to those used for the targets were deposited on MgO substrates by rf sputtering. The effects of sputtering time, rf power, and post-annealing on film microstructure and properties were studied in detail. Substrate temperature was found to have a significant influence on the film characteristics. Initial results show that deposition rates from a hollow cathode are an order of magnitude higher than those of a planar magnetron source at equivalent power levels. Large deposition rates allow for the coating of long lengths of wire

  10. Hollow waveguide cavity ringdown spectroscopy

    Science.gov (United States)

    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.

  11. Hollow core plasma channel generation

    International Nuclear Information System (INIS)

    Quast, Heinrich Martin

    2018-03-01

    The use of a hollow plasma channel in plasma-based acceleration has beneficial properties for the acceleration of electron and positron bunches. In the scope of the FLASHForward facility at DESY, the generation of such a plasma structure is examined. Therefore, the generation of a ring-shaped laser intensity profile with different techniques is analyzed. From the obtained intensity profiles the electron density of a hollow plasma channel is simulated in the focal region. Different parameters are scanned to understand their influence on the electron density distribution - an important parameter being, for example, the radius of the central region of the channel. In addition to the simulations, experiments are presented, during which a laser pulse is transformed into a hollow beam with a spiral phase plate. Subsequently, it forms a plasma during the interaction with hydrogen, where the plasma is imaged with interferometry. For energies above 0.9 mJ a hollow plasma structure can be observed at the location of first plasma formation.

  12. The Legend of Sleepy Hollow

    Institute of Scientific and Technical Information of China (English)

    Washington; Irving

    1987-01-01

    Part Ⅰ On the Eastern shore of the Hudson River there was a little valley, among high hills, which was one of the quietest places in the whole world. This little valley had long been known by the name of SIeepy Hollow. Many strange stories about ghosts were told and retold in the village situated there.

  13. Microstructured hollow fibers for ultrafiltration

    NARCIS (Netherlands)

    Culfaz, Pmar Zeynep; Culfaz, P.Z.; Rolevink, Hendrikus H.M.; van Rijn, C.J.M.; Lammertink, Rob G.H.; Wessling, Matthias

    2010-01-01

    Hollow fiber ultrafiltration membranes with a corrugated outer microstructure were prepared from a PES/PVP blend. The effect of spinning parameters such as air gap, take-up speed, polymer dope viscosity and coagulation value on the microstructure and membrane characteristics was investigated. Fibers

  14. Tensile Strength of GFRP Reinforcing Bars with Hollow Section

    Directory of Open Access Journals (Sweden)

    Young-Jun You

    2015-01-01

    Full Text Available Fiber reinforced polymer (FRP has been proposed to replace steel as a reinforcing bar (rebar due to its high tensile strength and noncorrosive material properties. One obstacle in using FRP rebars is high price. Generally FRP is more expensive than conventional steel rebar. There are mainly two ways to reduce the cost. For example, one is making the price of each composition cost of FRP rebar (e.g., fibers, resin, etc. lower than steel rebar. Another is making an optimized design for cross section and reducing the material cost. The former approach is not easy because the steel price is very low in comparison with component materials of FRP. For the latter approach, the cost could be cut down by reducing the material cost. Therefore, an idea of making hollow section over the cross section of FRP rebar was proposed in this study by optimizing the cross section design with acceptable tensile performance in comparison with steel rebar. In this study, glass reinforced polymer (GFRP rebars with hollow section and 19 mm of outer diameter were manufactured and tested to evaluate the tensile performance in accordance with the hollowness ratio. From the test results, it was observed that the tensile strength decreased almost linearly with increase of hollowness ratio and the elastic modulus decreased nonlinearly.

  15. Expanding hollow metal rings

    Science.gov (United States)

    Peacock, Harold B [Evans, GA; Imrich, Kenneth J [Grovetown, GA

    2009-03-17

    A sealing device that may expand more planar dimensions due to internal thermal expansion of a filler material. The sealing material is of a composition such that when desired environment temperatures and internal actuating pressures are reached, the sealing materials undergoes a permanent deformation. For metallic compounds, this permanent deformation occurs when the material enters the plastic deformation phase. Polymers, and other materials, may be using a sealing mechanism depending on the temperatures and corrosivity of the use. Internal pressures are generated by either rapid thermal expansion or material phase change and may include either liquid or solid to gas phase change, or in the gaseous state with significant pressure generation in accordance with the gas laws. Sealing material thickness and material composition may be used to selectively control geometric expansion of the seal such that expansion is limited to a specific facing and or geometric plane.

  16. Public Sphere as Digital Assemblage

    DEFF Research Database (Denmark)

    Salovaara-Moring, Inka

    the 1990s onwards digitalization brought concepts of network and complexity into the theoretical discourse. This relational turn changed the social ontology of the public sphere into a dynamic and complex system, erasing the division between the fields of reality (the world), representation (discourse......Normative theories of public sphere have struggled with the topic of materiality. The historical narrative of the ‘public sphere’ situated the phenomenon in specific spaces, where practices (public deliberation) and language (discourse) constructed political agencies, and further publics. From......), and subjectivity (agency). This changed the public sphere into an assemblage consisting of both human and non-human actors interactingin a highly dynamic, networked environment. This paper proposes a framework for considering this new materiality in the field of the public sphere: the assemblage and complexity...

  17. Differential Calculus on Quantum Spheres

    OpenAIRE

    Welk, Martin

    1998-01-01

    We study covariant differential calculus on the quantum spheres S_q^2N-1. Two classification results for covariant first order differential calculi are proved. As an important step towards a description of the noncommutative geometry of the quantum spheres, a framework of covariant differential calculus is established, including a particular first order calculus obtained by factorization, higher order calculi and a symmetry concept.

  18. Air Separation Using Hollow Fiber Membranes

    Science.gov (United States)

    Huang, Stephen E.

    2004-01-01

    300 different hydrocarbons commonly found in JP- 8, Jet A, and JP-5 fuels. I researched the major hydrocarbons that has a concentration of greater than 50 parts per million and found the vapor pressure data coefficients for a specific temperature range. The coefficients were applied to Antoine s Equation and Riedel's Equation to calculate the vapor pressures for that specific hydrocarbon in the specific temperature range. With the vapor pressure data scientists can formulate a fuel composition that has a lower vapor pressure profile, therefore making jet fuels less flammable. work, learn how to operate and examine the data from Gas Chromatograph and Mass Spectrometer, and develop new ways in applying hollow fiber membrane technology to other areas of environmental engineering. The United States military currently uses air separation technology and their primary The other side of making air travel safer is to reformulate the fuel. Analyses of three My goal this summer is to learn about hollow fiber membrane technologies and how they

  19. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    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.

  20. Silicon-Encapsulated Hollow Carbon Nanofiber Networks as Binder-Free Anodes for Lithium Ion Battery

    Directory of Open Access Journals (Sweden)

    Ding Nan

    2014-01-01

    Full Text Available Silicon-encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites were successfully synthesized by dip-coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As-synthesized hollow Si/C composites show excellent electrochemical performance when they are used as binder-free anodes for Li-ion batteries (LIBs. In particular, when the concentration of resol/ethanol solution is 3.0%, the product exhibits a large capacity of 841 mAh g−1 in the first cycle, prominent cycling stability, and good rate capability. The discharge capacity retention of it was ~90%, with 745 mAh g−1 after 50 cycles. The results demonstrate that the hollow Si/C composites are very promising as alternative anode candidates for high-performance LIBs.

  1. Direct numerical simulation of non-isothermal flow through dense bidisperse random arrays of spheres

    NARCIS (Netherlands)

    Tavassoli Estahbanati, H.; Peters, E.A.J.F.; Kuipers, J.A.M.

    2017-01-01

    Extensive direct numerical simulations were performed to obtain the heat transfer coefficients (HTC) of bidisperse random arrays of spheres. We have calculated the HTC for a range of compositions and solids volume fractions for mixtures of spheres with a size ratio of 1:2. The Reynolds numbers are

  2. Hollow fiber structures, methods of use thereof, methods of making, and pressure-retarded processes

    KAUST Repository

    Le, Lieu Ngoc; Bettahalli, Narasimha Murthy Srivatsa; Nunes, Suzana Pereira; Chung, Neal Tai-Shung

    2016-01-01

    Embodiments of the present disclosure provide for composite materials, methods of making composite materials, methods of using composite materials, and the like. In particular, the present application relates to hollow fibers and to pressure-retarded osmosis systems comprising said fibers. The hollow fibers have an inside layer and an outside layer, wherein the outside layer covers an outside surface of the inside layer, wherein the inside layer forms a boundary around the lumen, wherein the inside layer includes a bi-layer structure, wherein the bi-layer structure includes a sponge-like layer and a finger-like layer, wherein the sponge-like layer is disposed closer to the lumen of the hollow fiber and the finger-like layer is disposed on the sponge-like layer on the side opposite the lumen, wherein the outside layer includes a polyamide layer.

  3. Hollow fiber structures, methods of use thereof, methods of making, and pressure-retarded processes

    KAUST Repository

    Le, Lieu Ngoc

    2016-12-08

    Embodiments of the present disclosure provide for composite materials, methods of making composite materials, methods of using composite materials, and the like. In particular, the present application relates to hollow fibers and to pressure-retarded osmosis systems comprising said fibers. The hollow fibers have an inside layer and an outside layer, wherein the outside layer covers an outside surface of the inside layer, wherein the inside layer forms a boundary around the lumen, wherein the inside layer includes a bi-layer structure, wherein the bi-layer structure includes a sponge-like layer and a finger-like layer, wherein the sponge-like layer is disposed closer to the lumen of the hollow fiber and the finger-like layer is disposed on the sponge-like layer on the side opposite the lumen, wherein the outside layer includes a polyamide layer.

  4. Bamboo-inspired optimal design for functionally graded hollow cylinders.

    Directory of Open Access Journals (Sweden)

    Motohiro Sato

    Full Text Available The optimal distribution of the reinforcing fibers for stiffening hollow cylindrical composites is explored using the linear elasticity theory. The spatial distribution of the vascular bundles in wild bamboo, a nature-designed functionally graded material, is the basis for the design. Our results suggest that wild bamboos maximize their flexural rigidity by optimally regulating the radial gradation of their vascular bundle distribution. This fact provides us with a plant-mimetic design principle that enables the realization of high-stiffness and lightweight cylindrical composites.

  5. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  6. Method to fabricate hollow microneedle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kravitz, Stanley H [Placitas, NM; Ingersoll, David [Albuquerque, NM; Schmidt, Carrie [Los Lunas, NM; Flemming, Jeb [Albuquerque, NM

    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.

  7. PREPARATION AND CHARACTERIZATION OF POROUS WALLED HOLLOW GLASS MICROSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Raszewski, F; Erich Hansen, E; Ray Schumacher, R; David Peeler, D

    2008-04-21

    Porous-walled hollow glass microspheres (PWHGMs) of a modified alkali borosilicate composition have been successfully fabricated by combining the technology of producing hollow glass microspheres (HGMs) with the knowledge associated with porous glasses. HGMs are first formed by a powder glass--flame process, which are then transformed to PWHGMs by heat treatment and subsequent treatment in acid. Pore diameter and pore volume are most influenced by heat treatment temperature. Pore diameter is increased by a factor of 10 when samples are heat treated prior to acid leaching; 100 {angstrom} in non-heat treated samples to 1000 {angstrom} in samples heat treated at 600 C for 8 hours. As heat treatment time is increased from 8 hours to 24 hours there is a slight shift increase in pore diameter and little or no change in pore volume.

  8. Modeling the Electrostatics of Hollow Shell Suspensions: Ion Distribution, Pair Interactions, and Many-Body Effects.

    Science.gov (United States)

    Hallez, Yannick; Meireles, Martine

    2016-10-11

    Electrostatic interactions play a key role in hollow shell suspensions as they determine their structure, stability, thermodynamics, and rheology and also the loading capacity of small charged species for nanoreservoir applications. In this work, fast, reliable modeling strategies aimed at predicting the electrostatics of hollow shells for one, two, and many colloids are proposed and validated. The electrostatic potential inside and outside a hollow shell with a finite thickness and a specific permittivity is determined analytically in the Debye-Hückel (DH) limit. An expression for the interaction potential between two such hollow shells is then derived and validated numerically. It follows a classical Yukawa form with an effective charge depending on the shell geometry, permittivity, and inner and outer surface charge densities. The predictions of the Ornstein-Zernike (OZ) equation with this pair potential to determine equations of state are then evaluated by comparison to results obtained with a Brownian dynamics algorithm coupled to the resolution of the linearized Poisson-Boltzmann and Laplace equations (PB-BD simulations). The OZ equation based on the DLVO-like potential performs very well in the dilute regime as expected, but also quite well, and more surprisingly, in the concentrated regime in which full spheres exhibit significant many-body effects. These effects are shown to vanish for shells with small thickness and high permittivity. For highly charged hollow shells, we propose and validate a charge renormalization procedure. Finally, using PB-BD simulations, we show that the cell model predicts the ion distribution inside and outside hollow shells accurately in both electrostatically dilute and concentrated suspensions. We then determine the shell loading capacity as a function of salt concentration, volume fraction, and surface charge density for nanoreservoir applications such as drug delivery, sensing, or smart coatings.

  9. Synthesis and characterizations of spherical hollow composed of AgI nanoparticle using AgBr as the precursor

    International Nuclear Information System (INIS)

    Yang Ming; Zhou Kui

    2011-01-01

    Hollow spheres of AgI with an average radius of 100-200 nm have been prepared by a simple reaction between AgBr suspension and KI in the presence of gelatin. Gelatin played a decisive role as an inhibitor of the direct attack of I - ions to AgBr surfaces and coagulation of the growing AgI in producing the spherical AgI particles. The products were characterized by X-ray powder diffraction, transmission electron microscopy, UV-vis absorption spectroscopy and X-ray photoelectron spectra techniques. The band gaps are estimated to be 2.95 eV according to the results of optical measurements of the hollow spheres of AgI.

  10. Hierarchical Graphene-Encapsulated Hollow SnO2@SnS2 Nanostructures with Enhanced Lithium Storage Capability.

    Science.gov (United States)

    Xu, Wangwang; Xie, Zhiqiang; Cui, Xiaodan; Zhao, Kangning; Zhang, Lei; Dietrich, Grant; Dooley, Kerry M; Wang, Ying

    2015-10-14

    Complex hierarchical structures have received tremendous attention due to their superior properties over their constitute components. In this study, hierarchical graphene-encapsulated hollow SnO2@SnS2 nanostructures are successfully prepared by in situ sulfuration on the backbones of hollow SnO2 spheres via a simple hydrothermal method followed by a solvothermal surface modification. The as-prepared hierarchical SnO2@SnS2@rGO nanocomposite can be used as anode material in lithium ion batteries, exhibiting excellent cyclability with a capacity of 583 mAh/g after 100 electrochemical cycles at a specific current of 200 mA/g. This material shows a very low capacity fading of only 0.273% per cycle from the second to the 100th cycle, lower than the capacity degradation of bare SnO2 hollow spheres (0.830%) and single SnS2 nanosheets (0.393%). Even after being cycled at a range of specific currents varied from 100 mA/g to 2000 mA/g, hierarchical SnO2@SnS2@rGO nanocomposites maintain a reversible capacity of 664 mAh/g, which is much higher than single SnS2 nanosheets (374 mAh/g) and bare SnO2 hollow spheres (177 mAh/g). Such significantly improved electrochemical performance can be attributed to the unique hierarchical hollow structure, which not only effectively alleviates the stress resulting from the lithiation/delithiation process and maintaining structural stability during cycling but also reduces aggregation and facilitates ion transport. This work thus demonstrates the great potential of hierarchical SnO2@SnS2@rGO nanocomposites for applications as a high-performance anode material in next-generation lithium ion battery technology.

  11. Troubleshooting vSphere storage

    CERN Document Server

    Preston, Mike

    2013-01-01

    This is a step-by-step example-oriented tutorial aimed at showing the reader how to troubleshoot a variety of vSphere storage problems, and providing the reader with solutions that can be completed with minimal effort and time in order to limit damage to work.If you are a vSphere administrator, this is the book for you. This book will provide you with 'need to know' information about the various storage transports that ESXi utilizes, the tools and techniques we can use to identify problems, and the fundamental knowledge and steps to take to troubleshoot storage-related issues. Prior knowledge

  12. Preparation of hollow hydroxyapatite microspheres by the conversion of borate glass at near room temperature

    International Nuclear Information System (INIS)

    Yao, Aihua; Ai, Fanrong; Liu, Xin; Wang, Deping; Huang, Wenhai; Xu, Wei

    2010-01-01

    Hollow hydroxyapatite microspheres, consisting of a hollow core and a porous shell, were prepared by converting Li 2 O-CaO-B 2 O 3 glass microspheres in dilute phosphate solution at 37 o C. The results confirmed that Li 2 O-CaO-B 2 O 3 glass was transformed to hydroxyapatite without changing the external shape and dimension of the original glass object. Scanning electron microscopy images showed the shell wall of the microsphere was built from hydroxyapatite particles, and these particles spontaneously align with one another to form a porous sphere with an interior cavity. Increase in phosphate concentration resulted in an increase in the reaction rate, which in turn had an effect on shell wall structure of the hollow hydroxyapatite microsphere. For the Li 2 O-CaO-B 2 O 3 glass microspheres reacted in low-concentration K 2 HPO 4 solution, lower reaction rate and a multilayered microstructure were observed. On the other hand, the glass microspheres reacted in higher phosphate solution converted more rapidly and produced a single hydroxyapatite layer. Furthermore, the mechanism of forming hydroxyapatite hollow microsphere was described.

  13. Facile synthesis of hollow dendritic Ag/Pt alloy nanoparticles for enhanced methanol oxidation efficiency.

    Science.gov (United States)

    Sui, Ning; Wang, Ke; Shan, Xinyao; Bai, Qiang; Wang, Lina; Xiao, Hailian; Liu, Manhong; Colvin, Vicki L; Yu, William W

    2017-11-14

    Hollow dendritic Ag/Pt alloy nanoparticles were synthesized by a double template method: Ag nanoparticles as the hard template to obtain hollow spheres by a galvanic replacement reaction between PtCl 6 2- and metallic Ag and surfactant micelles (Brij58) as the soft template to generate porous dendrites. The formation of a Ag/Pt alloy phase was confirmed by XRD and HRTEM. Elemental mapping and line scanning revealed the formation of the hollow architecture. We studied the effects of the Ag/Pt ratio, surfactant and reaction temperature on the morphology. In addition, we explored the formation process of hollow dendritic Ag/Pt nanoparticles by tracking the morphologies of the nanostructures formed at different stages. In order to improve the electrocatalytic property, we controlled the size of the nanoparticles and the thickness of the shell by adjusting the amount of the precursor. We found that these Ag/Pt alloy nanoparticles exhibited high activity (440 mA mg -1 ) and stability as an electrocatalyst for catalyzing methanol oxidation.

  14. Construction of anatase/rutile TiO2 hollow boxes for highly efficient photocatalytic performance

    Science.gov (United States)

    Jia, Changchao; Zhang, Xiao; Yang, Ping

    2018-02-01

    Hollow TiO2 hierarchical boxes with suitable anatase and rutile ratios were designed for photocatalysis. The unique hierarchical structure was fabricated via a Topotactic synthetic method. CaTiO3 cubes were acted as the sacrificial templates to create TiO2 hollow hierarchical boxes with well-defined phase distribution. The phase composition of the hollow TiO2 hierarchical boxes is similar to that of TiO2 P25 nanoparticles (∼80% anatase, and 20% rutile). Compared with nanaoparticles, TiO2 hollow boxes with hierarchical structures exhibited an excellent performance in the photocatalytic degradation of methylene blue organic pollutant. Quantificationally, the degradation rate of the hollow boxes is higher than that of TiO2 P25 nanoparticles by a factor of 2.7. This is ascribed that hollow structure provide an opportunity for using incident light more efficiently. The surface hierarchical and well-organized porous structures are beneficial to supply more active sites and enough transport channels for reactant molecules. The boxes consist of single crystal anatase and rutile combined well with each other, which gives photon-generated carriers transfer efficiently.

  15. Spheres of discharge of springs

    Science.gov (United States)

    Springer, Abraham E.; Stevens, Lawrence E.

    2009-02-01

    Although springs have been recognized as important, rare, and globally threatened ecosystems, there is as yet no consistent and comprehensive classification system or common lexicon for springs. In this paper, 12 spheres of discharge of springs are defined, sketched, displayed with photographs, and described relative to their hydrogeology of occurrence, and the microhabitats and ecosystems they support. A few of the spheres of discharge have been previously recognized and used by hydrogeologists for over 80 years, but others have only recently been defined geomorphologically. A comparison of these spheres of discharge to classification systems for wetlands, groundwater dependent ecosystems, karst hydrogeology, running waters, and other systems is provided. With a common lexicon for springs, hydrogeologists can provide more consistent guidance for springs ecosystem conservation, management, and restoration. As additional comprehensive inventories of the physical, biological, and cultural characteristics are conducted and analyzed, it will eventually be possible to associate spheres of discharge with discrete vegetation and aquatic invertebrate assemblages, and better understand the habitat requirements of rare or unique springs species. Given the elevated productivity and biodiversity of springs, and their highly threatened status, identification of geomorphic similarities among spring types is essential for conservation of these important ecosystems.

  16. Neuroscience in the public sphere.

    Science.gov (United States)

    O'Connor, Cliodhna; Rees, Geraint; Joffe, Helene

    2012-04-26

    The media are increasingly fascinated by neuroscience. Here, we consider how neuroscientific discoveries are thematically represented in the popular press and the implications this has for society. In communicating research, neuroscientists should be sensitive to the social consequences neuroscientific information may have once it enters the public sphere. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Neuroscience in the Public Sphere

    OpenAIRE

    O'Connor, Cliodhna; Rees, Geraint; Joffe, Helene

    2012-01-01

    The media are increasingly fascinated by neuroscience. Here, we consider how neuroscientific discoveries are thematically represented in the popular press and the implications this has for society. In communicating research, neuroscientists should be sensitive to the social consequences neuroscientific information may have once it enters the public sphere.

  18. Outer Sphere Adsorption of Pb(II)EDTA on Goethite

    Energy Technology Data Exchange (ETDEWEB)

    Bargar, John R

    1999-07-16

    FTIR and EXAFS spectroscopic measurements were performed on Pb(II)EDTA adsorbed on goethite as functions of pH (4-6), Pb(II)EDTA concentration (0.11 {micro}M - 72 {micro}M), and ionic strength (16 {micro}M - 0.5M). FTIR measurements show no evidence for carboxylate-Fe(III) bonding or protonation of EDTA at Pb:EDTA = 1:1. Both FTIR and EXAFS measurements suggest that EDTA acts as a hexadentate ligand, with all four of its carboxylate and both amine groups bonded to Pb(II). No evidence was observed for inner-sphere Pb(II)-goethite bonding at Pb:EDTA = 1:1. Hence, the adsorbed complexes should have composition Pb(II)EDTA{sup 2{minus}}. Since substantial uptake of PbEDTA(II){sup 2{minus}} occurred in the samples, we infer that Pb(II)EDTA{sup 2{minus}} adsorbed as outer-sphere complexes and/or as complexes that lose part of their solvation shells and hydrogen bond directly to goethite surface sites. We propose the term ''hydration-sphere'' for the latter type of complexes because they should occupy space in the primary hydration spheres of goethite surface functional groups, and to distinguish this mode of sorption from common structural definitions of inner- and outer-sphere complexes. The similarity of Pb(II) uptake isotherms to those of other divalent metal ions complexed by EDTA suggests that they too adsorb by these mechanisms. The lack of evidence for inner-sphere EDTA-Fe(III) bonding suggests that previously proposed metal-ligand - promoted dissolution mechanisms should be modified, specifically to account for the presence of outer-sphere precursor species.

  19. Röntgen spheres around active stars

    Science.gov (United States)

    Locci, Daniele; Cecchi-Pestellini, Cesare; Micela, Giuseppina; Ciaravella, Angela; Aresu, Giambattista

    2018-01-01

    X-rays are an important ingredient of the radiation environment of a variety of stars of different spectral types and age. We have modelled the X-ray transfer and energy deposition into a gas with solar composition, through an accurate description of the electron cascade following the history of the primary photoelectron energy deposition. We test and validate this description studying the possible formation of regions in which X-rays are the major ionization channel. Such regions, called Röntgen spheres may have considerable importance in the chemical and physical evolution of the gas embedding the emitting star. Around massive stars the concept of Röntgen sphere appears to be of limited use, as the formation of extended volumes with relevant levels of ionization is efficient just in a narrow range of gas volume densities. In clouds embedding low-mass pre-main-sequence stars significant volumes of gas are affected by ionization levels exceeding largely the cosmic-ray background ionization. In clusters arising in regions of vigorous star formation X-rays create an ionization network pervading densely the interstellar medium, and providing a natural feedback mechanism, which may affect planet and star formation processes.

  20. Hollow nanocrystals and method of making

    Science.gov (United States)

    Alivisatos, A Paul [Oakland, CA; Yin, Yadong [Moreno Valley, CA; Erdonmez, Can Kerem [Berkeley, CA

    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.

  1. Controllable synthesis of helical, straight, hollow and nitrogen-doped carbon nanofibers and their magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xun [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Zheng, E-mail: zhengxu@nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructure, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    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.

  2. One-Step Synthesis of Hollow Titanate (Sr/Ba Ceramic Fibers for Detoxification of Nerve Agents

    Directory of Open Access Journals (Sweden)

    Satya R. Agarwal

    2012-01-01

    Full Text Available Poly(vinyl pyrrolidone(PVP/(strontium/barium acetate/titanium isopropoxide composite fibers were prepared by electrospinning technique via sol-gel process. Diameters of fibers prepared by calcinations of PVP composite fibers were 80–140 nm (solid and 1.2-2.2 μm (hollow fibers prepared by core-shell method. These fibers were characterized using scanning electron microscope (SEM, X-ray diffraction (XRD, and transmission electron microscope (TEM analytical techniques. XRD results showed better crystalline nature of the materials when calcined at higher temperatures. SEM and TEM results clearly showed the formation of hollow submicrometer tubes. The surface area of the samples determined by BET analysis indicated that hollow fibers have ~20% higher surface area than solid fibers. The UV studies indicate better detoxification properties of the hollow fibers compared to solid fibers.

  3. Pressure-assisted synthesis of HKUST-1 thin film on polymer hollow fiber at room temperature toward gas separation.

    Science.gov (United States)

    Mao, Yiyin; Li, Junwei; Cao, Wei; Ying, Yulong; Sun, Luwei; Peng, Xinsheng

    2014-03-26

    The scalable fabrication of continuous and defect-free metal-organic framework (MOF) films on the surface of polymeric hollow fibers, departing from ceramic supported or dense composite membranes, is a huge challenge. The critical way is to reduce the growth temperature of MOFs in aqueous or ethanol solvents. In the present work, a pressure-assisted room temperature growth strategy was carried out to fabricate continuous and well-intergrown HKUST-1 films on a polymer hollow fiber by using solid copper hydroxide nanostrands as the copper source within 40 min. These HKUST-1 films/polyvinylidenefluoride (PVDF) hollow fiber composite membranes exhibit good separation performance for binary gases with selectivity 116% higher than Knudsen values via both inside-out and outside-in modes. This provides a new way to enable for scale-up preparation of HKUST-1/polymer hollow fiber membranes, due to its superior economic and ecological advantages.

  4. Hollow rods for the oil producing industry

    Energy Technology Data Exchange (ETDEWEB)

    Khalimova, L M; Elyasheva, M A

    1970-01-01

    Hollow sucker rods have several advantages over conventional ones. The hollow rods actuate the well pump and at the same time conduct produced fluids to surface. When paraffin deposition occurs, it can be minimized by injecting steam, hot oil or hot water into the hollow rod. Other chemicals, such as demulsifiers, scale inhibitors, corrosion inhibitors, etc., can also be placed in the well through the hollow rods. This reduces cost of preventive treatments, reduces number of workovers, increases oil production, and reduces cost of oil. Because the internal area of the rod is small, the passing liquids have a high velocity and thereby carry sand and dirt out of the well. This reduces pump wear between the piston and the plunger. Specifications of hollow rods, their operating characteristics, and results obtained with such rods under various circumstances are described.

  5. Sandwich-structured hollow fiber membranes for osmotic power generation

    KAUST Repository

    Fu, Feng Jiang; Zhang, Sui; Chung, Neal Tai-Shung

    2015-01-01

    In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications. © 2015 Elsevier B.V.

  6. Sandwich-structured hollow fiber membranes for osmotic power generation

    KAUST Repository

    Fu, Feng Jiang

    2015-11-01

    In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications. © 2015 Elsevier B.V.

  7. Tessellating the Sphere with Regular Polygons

    Science.gov (United States)

    Soto-Johnson, Hortensia; Bechthold, Dawn

    2004-01-01

    Tessellations in the Euclidean plane and regular polygons that tessellate the sphere are reviewed. The regular polygons that can possibly tesellate the sphere are spherical triangles, squares and pentagons.

  8. Preparation and crystallization of hollow α-Fe{sub 2}O{sub 3} microspheres following the gas-bubble template method

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, L. de los Santos, E-mail: ld301@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); León Félix, L. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Laboratory of Magnetic Characterization, Instituto de Física, Universidade de Brasília, DF 70910-900, Brasilia (Brazil); Espinoza Suarez, S.M.; Bustamante Dominguez, A.G. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Mitrelias, T.; Holmes, S. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); Moreno, N.O. [Departamento de Física, Universidade Federal de Sergipe, 49100-000, Sao Cristóvao, Sergipe (Brazil); Albino Aguiar, J. [Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife (Brazil); Barnes, C.H.W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom)

    2016-02-01

    In this work we report the formation of hollow α-Fe{sub 2}O{sub 3} (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO{sub 3}){sub 3}.9H{sub 2}O and citric acid in water by sol–gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250–400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. - Highlights: • Formation of hollow hematite microspheres by the gas-bubble template method. • This technique does not require hard templates or special conditions of atmosphere. • Annealing promotes the transition magnetite to maghemite to hematite. • Crystallization of the hematite shells increase with annealing temperature.

  9. Composites

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1983-01-01

    This chapter discusses the roles of composite laminates and aggregates in cryogenic technology. Filamentary-reinforced composites are emphasized because they are the most widely used composite materials. Topics considered include composite systems and terminology, design and fabrication, composite failure, high-pressure reinforced plastic laminates, low-pressure reinforced plastics, reinforced metals, selectively reinforced structures, the effect of cryogenic temperatures, woven-fabric and random-mat composites, uniaxial fiber-reinforced composites, composite joints in cryogenic structures, joining techniques at room temperature, radiation effects, testing laminates at cryogenic temperatures, static and cyclic tensile testing, static and cyclic compression testing, interlaminar shear testing, secondary property tests, and concrete aggregates. It is suggested that cryogenic composite technology would benefit from the development of a fracture mechanics model for predicting the fitness-for-purpose of polymer-matrix composite structures

  10. Capillary holdup between vertical spheres

    Directory of Open Access Journals (Sweden)

    S. Zeinali Heris

    2009-12-01

    Full Text Available The maximum volume of liquid bridge left between two vertically mounted spherical particles has been theoretically determined and experimentally measured. As the gravitational effect has not been neglected in the theoretical model, the liquid interface profile is nonsymmetrical around the X-axis. Symmetry in the interface profile only occurs when either the particle size ratio or the gravitational force becomes zero. In this paper, some equations are derived as a function of the spheres' sizes, gap width, liquid density, surface tension and body force (gravity/centrifugal to estimate the maximum amount of liquid that can be held between the two solid spheres. Then a comparison is made between the result based on these equations and several experimental results.

  11. Archaic artifacts resembling celestial spheres

    Science.gov (United States)

    Dimitrakoudis, S.; Papaspyrou, P.; Petoussis, V.; Moussas, X.

    We present several bronze artifacts from the Archaic Age in Greece (750-480 BC) that resemble celestial spheres or forms of other astronomical significance. They are studied in the context of the Dark Age transition from Mycenaean Age astronomical themes to the philosophical and practical revival of astronomy in the Classical Age with its plethora of astronomical devices. These artifacts, mostly votive in nature are spherical in shape and appear in a variety of forms their most striking characteristic being the depiction of meridians and/or an equator. Most of those artifacts come from Thessaly, and more specifically from the temple of Itonia Athena at Philia, a religious center of pan-Hellenic significance. Celestial spheres, similar in form to the small artifacts presented in this study, could be used to measure latitudes, or estimate the time at a known place, and were thus very useful in navigation.

  12. Spheres of Justice within Schools

    DEFF Research Database (Denmark)

    Sabbagh, Clara; Resh, Nura; Mor, Michal

    2006-01-01

    This article argues that there are distinct spheres of justice within education and examines a range of justice norms and distribution rules that characterize the daily life of schools and classrooms. Moving from the macro to micro level, we identify the following five areas: the right to education......, the allocation of (or selection into) learning places, teaching–learning practices, teachers’ treatment of students, and student evaluations of grade distribution. We discuss the literature on the beliefs by students and teachers about the just distribution of educational goods in these five domains......, and on the practices used in the actual allocation of these goods. In line with normative ‘spheres of justice’ arguments in social theory, we conclude that the ideals of social justice within schools vary strongly according to the particular resource to be distributed. Moreover, these ideals often do not correspond...

  13. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David)

    2008-11-03

    Hollow micro-nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best-known example of the former is the use of fly-ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well-established approaches, such as conventional hard-templating and soft-templating methods, as well as newly emerging methods based on sacrificial templating and template-free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle-type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.

  14. A novel method for preparation of hollow and solid carbon spheres

    Indian Academy of Sciences (India)

    Wintec

    strength (Li et al 2006), which make them appropriate materials to be used in lithium-ion ... efficient and low cost method to prepare HCSs and SCSs by the reaction of .... Li L C, Song H H and Chen X H 2006 Carbon 44 596. Wang P et al 2007 ...

  15. The Universe is Like a Hollowed Sphere. The Wave Concept of Time

    Directory of Open Access Journals (Sweden)

    Andrzej W. Głuszak

    2015-07-01

    Full Text Available There is space for new ideas of the essence and the entity of time. The article refers to our time concept as a special wave type and presents results of our investigations on this subject. Thus, time defined as waves and an energy carrier could give explanation to multiple unclear phenomena. It could explicate gravity, organization in the planetary systems and light speed limit. A hypothesis that matter exists due to time wave motion would emerge from the elementary particle mass generation by the waves. Time becomes the main driving force in the Universe. The discussed thoughts need further analyses and verification but their confirmation may mean civilization changes.

  16. The optical levitation of spheres

    International Nuclear Information System (INIS)

    Roosen, G.

    1979-01-01

    In this article we are dealing with optical levitation, that is the possibility of maintaining particles in a stable equilibrium position in air or vacuum by means of laser beams. In the first part, we review the methods used to calculate the force exerted on a sphere by a laser beam. The axial and transverse force components could be obtained either by applying Debye theory to laser beams which have a non-uniform energy distribution or by using, in the case of large spheres, a geometrical optics approach. From the results achieved with the geometrical optics approach, we derive, in a second part, the required stable equilibrium conditions for a sphere placed either in a vertical beam or in two horizontal ones having the same axis but opposite direction. In the last part, we describe in detail the levitation experiments carried out using either a vertical or two horizontal beams. In conclusion, we point out some applications of optical levitation, emphasizing especially the suspension by optical levitation of the targets used in laser fusion experiments. (author) [fr

  17. Facile synthesis and electrochemical properties of continuous porous spheres assembled from defect-rich, interlayer-expanded, and few-layered MoS2/C nanosheets for reversible lithium storage

    Science.gov (United States)

    Chen, Biao; Lu, Huihui; Zhao, Naiqin; Shi, Chunsheng; Liu, Enzuo; He, Chunnian; Ma, Liying

    2018-05-01

    Hollow or continuous porous hierarchical MoS2/C structures with large Li-ion and electron transport kinetics, and high structural stability are urgent needs for their application in lithium ion batteries. In this regard, a novel continuous porous micro-sphere constructed from defect-rich, interlayer-expanded, and few-layered MoS2/C nanosheets is successfully synthesized through a facile one-pot hydrothermal method. The polyvinyl pyrrolidone surfactant serves as carbon source and supporter, while the CS2 works as soft template and sulfur source during hydrothermal process. The morphologies, structures, and electrochemical properties are systematically characterized. Importantly, it should be noted that the unique porous micro-spheres with merits of rich-defect, expanded-interlayer, few-layer (integrating carbon are favorable for lithium ion batteries application. When the uniform composites are used as lithium ion batteries anode materials, they deliver a high reversible capacity, excellent cycling performance (average capacity fading of 0.037% per cycle at 0.2 A g-1), and good rate capability.

  18. Electrorheological properties of suspensions of hollow globular titanium oxide/polypyrrole particles

    Czech Academy of Sciences Publication Activity Database

    Sedlačík, M.; Mrlík, M.; Pavlínek, V.; Sáha, P.; Quadrat, Otakar

    2012-01-01

    Roč. 290, č. 1 (2012), s. 41-48 ISSN 0303-402X R&D Projects: GA ČR GA202/09/1626 Institutional research plan: CEZ:AV0Z40500505 Keywords : electrorheology * titanium oxide * hollow globular clusters Subject RIV: JI - Composite Materials Impact factor: 2.161, year: 2012

  19. Polyaniline coated Fe3O4 hollow nanospheres as anode materials for lithium ion batteries

    DEFF Research Database (Denmark)

    Wang, Xiaoliang; Liu, Yanguo; Han, Hongyan

    2017-01-01

    Polyaniline (PANI) coated Fe3O4 hollow nanospheres (h-Fe3O4@ PANI) have been successfully synthesized and investigated as anode materials for lithium ion batteries (LIBs). The structure and composition analyses have been performed by employing X-ray diffraction (XRD), scanning electron microscopy...

  20. High flux polyethersulfone-polyimide blend hollow fiber membranes for gas separation

    NARCIS (Netherlands)

    Kapantaidakis, G.; Koops, G.H.

    2002-01-01

    In this work, the preparation of gas separation hollow fibers based on polyethersulfone Sumikaexcel (PES) and polyimide Matrimid 5218 (PI) blends, for three different compositions (i.e. PES/PI: 80/20, 50/50 and 20/80 wt.%), is reported. The dry/wet spinning process has been applied to prepare

  1. Mastering VMware vSphere 5

    CERN Document Server

    Lowe, Scott

    2011-01-01

    A new and updated edition of bestselling Mastering VMware vSphere 4 Written by leading VMware expert, this book covers all the features and capabilities of VMware vSphere. You'll learn how to install, configure, operate, manage, and secure the latest release.Covers all the new features and capabilities of the much-anticipated new release of VMware vSphereDiscusses the planning, installation, operation, and management for the latest releaseReviews migration to the latest vSphere softwareOffers hands-on instruction and clear explanations with real-world examples Mastering VMware vSphere is the

  2. Formation of Uniform Hollow Silica microcapsules

    Science.gov (United States)

    Yan, Huan; Kim, Chanjoong

    2013-03-01

    Microcapsules are small containers with diameters in the range of 0.1 - 100 μm. Mesoporous microcapsules with hollow morphologies possess unique properties such as low-density and high encapsulation capacity, while allowing controlled release by permeating substances with a specific size and chemistry. Our process is a one-step fabrication of monodisperse hollow silica capsules with a hierarchical pore structure and high size uniformity using double emulsion templates obtained by the glass-capillary microfluidic technique to encapsulate various active ingredients. These hollow silica microcapsules can be used as biomedical applications such as drug delivery and controlled release.

  3. Microring embedded hollow polymer fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Linslal, C. L., E-mail: linslal@gmail.com; Sebastian, S.; Mathew, S.; Radhakrishnan, P.; Nampoori, V. P. N.; Girijavallabhan, C. P.; Kailasnath, M. [International School of Photonics, Cochin University of Science and Technology, Cochin 22 (India)

    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. The sphere-PAC fuel code 'SPHERE-3'

    Energy Technology Data Exchange (ETDEWEB)

    Wallin, H

    2000-07-01

    Sphere-PAC fuel is an advanced nuclear fuel, in which the cladding tube is filled with small fuel spheres instead of the more usual fuel pellets. At PSI, the irradiation behaviour of sphere-PAC fuel is calculated using the computer code SPHERE-3. The paper describes the present status of the SPHERE-3 code, and some results of the qualification process against experimental data. (author)

  5. A FEW CONSIDERATIONS REGARDING THE SPHERE OF FINANCIAL RELATIONS

    OpenAIRE

    Bota Anton Florin

    2009-01-01

    The author discusses his financial affairs sphere, looking at this issue under a double aspect: analysis of the financial relations sphere and analyzing the financial activity sphere. Analysis of the financial relations sphere is made on the basis of fou

  6. Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

    International Nuclear Information System (INIS)

    Lu, Yanqi; Liu, Mingda; Nie, Huagui; Gu, Cancan; Liu, Ming; Yang, Zhi; Yang, Keqin; Chen, Xi’an; Huang, Shaoming

    2016-01-01

    Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a self-supporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metal-free hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO_2 spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.Graphical AbstractHollow graphene balls with a self-supporting structure have been successfully fabricated, through using a new strategy that involves direct metal-free catalytic growth from 3D assembly of SiO_2 spheres. The hollow graphene balls can exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction

  7. Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yanqi; Liu, Mingda; Nie, Huagui, E-mail: huaguinie@126.com; Gu, Cancan; Liu, Ming; Yang, Zhi, E-mail: yang201079@126.com; Yang, Keqin; Chen, Xi’an; Huang, Shaoming, E-mail: smhuang@wzu.edu.cn [Wenzhou University, Nanomaterials and Chemistry Key Laboratory (China)

    2016-06-15

    Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a self-supporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metal-free hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO{sub 2} spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.Graphical AbstractHollow graphene balls with a self-supporting structure have been successfully fabricated, through using a new strategy that involves direct metal-free catalytic growth from 3D assembly of SiO{sub 2} spheres. The hollow graphene balls can exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction.

  8. Generating perfect fluid spheres in general relativity

    Science.gov (United States)

    Boonserm, Petarpa; Visser, Matt; Weinfurtner, Silke

    2005-06-01

    Ever since Karl Schwarzschild’s 1916 discovery of the spacetime geometry describing the interior of a particular idealized general relativistic star—a static spherically symmetric blob of fluid with position-independent density—the general relativity community has continued to devote considerable time and energy to understanding the general-relativistic static perfect fluid sphere. Over the last 90 years a tangle of specific perfect fluid spheres has been discovered, with most of these specific examples seemingly independent from each other. To bring some order to this collection, in this article we develop several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. These transformation theorems sometimes lead to unexpected connections between previously known perfect fluid spheres, sometimes lead to new previously unknown perfect fluid spheres, and in general can be used to develop a systematic way of classifying the set of all perfect fluid spheres.

  9. Generating perfect fluid spheres in general relativity

    International Nuclear Information System (INIS)

    Boonserm, Petarpa; Visser, Matt; Weinfurtner, Silke

    2005-01-01

    Ever since Karl Schwarzschild's 1916 discovery of the spacetime geometry describing the interior of a particular idealized general relativistic star--a static spherically symmetric blob of fluid with position-independent density--the general relativity community has continued to devote considerable time and energy to understanding the general-relativistic static perfect fluid sphere. Over the last 90 years a tangle of specific perfect fluid spheres has been discovered, with most of these specific examples seemingly independent from each other. To bring some order to this collection, in this article we develop several new transformation theorems that map perfect fluid spheres into perfect fluid spheres. These transformation theorems sometimes lead to unexpected connections between previously known perfect fluid spheres, sometimes lead to new previously unknown perfect fluid spheres, and in general can be used to develop a systematic way of classifying the set of all perfect fluid spheres

  10. SURFACES OF HARD-SPHERE SYSTEMS

    Directory of Open Access Journals (Sweden)

    Dietrich Stoyan

    2014-07-01

    Full Text Available In various situations surfaces appear that are formed by systems of hard spheres. Examples are porous layers as surfaces of sand heaps and biofilms or fracture surfaces of concrete. The present paper considers models where a statistically homogeneous system of hard spheres with random radii is intersected by a plane and the surface is formed by the spheres with centers close to this plane. Formulae are derived for various characteristics of such surfaces: for the porosity profile, i.e. the local porosity in dependence on the distance from the section plane and for the geometry of the sphere caps that look above the section plane.It turns out that these characteristics only depend on the first-order characteristics of the sphere system, its sphere density and the sphere radius distribution.Comparison with empirically studied biofilms shows that the model is realistic.

  11. Fusion breeder sphere - PAC blanket design

    International Nuclear Information System (INIS)

    Sullivan, J.D.; Palmer, B.J.F.

    1987-11-01

    There is a considerable world-wide effort directed toward the production of materials for fusion reactors. Many ceramic fabrication groups are working on making lithium ceramics in a variety of forms, to be incorporated into the tritium breeding blanket which will surround the fusion reactor. Current blanket designs include ceramic in either monolithic or packed sphere bed (sphere-pac) forms. The major thrust at AECL is the production of lithium aluminate spheres to be incorporated in a sphere-pac bed. Contemporary studies on breeder blanket design offer little insight into the requirements on the sizes of the spheres. This study examined the parameters which determine the properties of pressure drop and coolant requirements. It was determined that an optimised sphere-pac bed would be composed of two diameters of spheres: 75 weight % at 3 mm and 25 weight % at 0.3 mm

  12. Rapid Temperature Swing Adsorption using Polymeric/Supported Amine Hollow Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Chance, Ronald [Georgia Tech Research Corporation, Atlanta, GA (United States); Chen, Grace [Georgia Tech Research Corporation, Atlanta, GA (United States); Dai, Ying [Georgia Tech Research Corporation, Atlanta, GA (United States); Fan, Yanfang [Georgia Tech Research Corporation, Atlanta, GA (United States); Jones, Christopher [Georgia Tech Research Corporation, Atlanta, GA (United States); Kalyanaraman, Jayashree [Georgia Tech Research Corporation, Atlanta, GA (United States); Kawajiri, Yoshiaki [Georgia Tech Research Corporation, Atlanta, GA (United States); Koros, William [Georgia Tech Research Corporation, Atlanta, GA (United States); Lively, Ryan [Georgia Tech Research Corporation, Atlanta, GA (United States); McCool, Benjamin [Georgia Tech Research Corporation, Atlanta, GA (United States); Pang, Simon [Georgia Tech Research Corporation, Atlanta, GA (United States); Realff, Matthew [Georgia Tech Research Corporation, Atlanta, GA (United States); Rezaei, Fateme [Georgia Tech Research Corporation, Atlanta, GA (United States); Searcy, Katherine [Georgia Tech Research Corporation, Atlanta, GA (United States); Sholl, David [Georgia Tech Research Corporation, Atlanta, GA (United States); Subramanian, Swernath [Georgia Tech Research Corporation, Atlanta, GA (United States); Pang, Simon [Georgia Tech Research Corporation, Atlanta, GA (United States)

    2015-03-31

    This project is a bench-scale, post-combustion capture project carried out at Georgia Tech (GT) with support and collaboration with GE, Algenol Biofuels, Southern Company and subcontract to Trimeric Corporation. The focus of the project is to develop a process based on composite amine-functionalized oxide / polymer hollow fibers for use as contactors in a rapid temperature swing adsorption post-combustion carbon dioxide capture process. The hollow fiber morphology allows coupling of efficient heat transfer with effective gas contacting, potentially giving lower parasitic loads on the power plant compared to traditional contacting strategies using solid sorbents.

  13. Acid functionalized, highly dispersed carbonaceous spheres: an effective solid acid for hydrolysis of polysaccharides

    Science.gov (United States)

    Jiang, Yijun; Li, Xiutao; Cao, Quan; Mu, Xindong

    2011-02-01

    Highly dispersed carbonaceous spheres with sulfonic acid groups were successfully prepared from glucose by hydrothermal method. Transmission electron microscopy (TEM) showed the as-synthesized carbonaceous materials were uniform, spherical in shape with an average diameter of about 450 nm. Fourier transform infrared (FT-IR) proved that -SO3H, -COOH, OH groups were grafted on the surface of the carbonaceous spheres during the sulfonation. Interestingly, the functionalized carbonaceous spheres exhibited high dispersibility in the polar solvent due to the hydrophilic groups on the surface. The mechanism of the formation for the carbonaceous spheres was also discussed based on the analysis of structure and composition. At last, the functionalized carbonaceous spheres were employed as solid acid to hydrolyze starch and cellulose. By comparison, the as-synthesized catalyst showed considerable high yield of glucose.

  14. Acid functionalized, highly dispersed carbonaceous spheres: an effective solid acid for hydrolysis of polysaccharides

    International Nuclear Information System (INIS)

    Jiang Yijun; Li Xiutao; Cao Quan; Mu Xindong

    2011-01-01

    Highly dispersed carbonaceous spheres with sulfonic acid groups were successfully prepared from glucose by hydrothermal method. Transmission electron microscopy (TEM) showed the as-synthesized carbonaceous materials were uniform, spherical in shape with an average diameter of about 450 nm. Fourier transform infrared (FT-IR) proved that –SO 3 H, –COOH, OH groups were grafted on the surface of the carbonaceous spheres during the sulfonation. Interestingly, the functionalized carbonaceous spheres exhibited high dispersibility in the polar solvent due to the hydrophilic groups on the surface. The mechanism of the formation for the carbonaceous spheres was also discussed based on the analysis of structure and composition. At last, the functionalized carbonaceous spheres were employed as solid acid to hydrolyze starch and cellulose. By comparison, the as-synthesized catalyst showed considerable high yield of glucose.

  15. Capture and separation of l-histidine through optimized zinc-decorated magnetic silica spheres.

    Science.gov (United States)

    Cardoso, Vanessa F; Sebastián, Víctor; Silva, Carlos J R; Botelho, Gabriela; Lanceros-Méndez, Senentxu

    2017-09-01

    Zinc-decorated magnetic silica spheres were developed, optimized and tested for the capture and separation of l-histidine. The magnetic silica spheres were prepared using a simple sol-gel method and show excellent magnetic characteristics, adsorption capacity toward metal ions, and stability in aqueous solution in a wide pH range. The binding capacity of zinc-decorated magnetic silica spheres to histidine proved to be strongly influenced by the morphology, composition and concentration of metal at the surface of the magnetic silica spheres and therefore these parameters should be carefully controlled in order to maximize the performance for protein purification purposes. Optimized zinc-decorated magnetic silica spheres demonstrate a binding capacity to l-histidine of approximately 44mgg -1 at the optimum binding pH buffer. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2011-01-01

    Strategies are open compositions to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them in full...

  17. Composition

    DEFF Research Database (Denmark)

    2014-01-01

    Memory Pieces are open compositions to be realised solo by an improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound files will in some cases only provide a few minutes' sample. Please DOWNLOAD them to hear them...

  18. Modeling High Pressure Micro Hollow Cathode Discharges

    National Research Council Canada - National Science Library

    Boeuf, Jean-Pierre; Pitchford, Leanne

    2004-01-01

    This report results from a contract tasking CPAT as follows: The Grantee will perform theoretical modeling of point, surface, and volume high-pressure plasmas created using Micro Hollow Cathode Discharge sources...

  19. optimizing compressive strength characteristics of hollow building

    African Journals Online (AJOL)

    eobe

    Keywords: hollow building Blocks, granite dust, sand, partial replacement, compressive strength. 1. INTRODUCTION ... exposed to extreme climate. The physical ... Sridharan et al [13] conducted shear strength studies on soil-quarry dust.

  20. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David); Archer, Lynden A.; Yang, Zichao

    2008-01-01

    for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic

  1. Solvothermal synthesis and characterization of ceria with solid and hollow spherical and multilayered morphologies

    International Nuclear Information System (INIS)

    He, Lei; Li, Junping; Feng, Zhihai; Sun, Dongfeng; Wang, Tingyu; Li, Ruixing; Xu, Yaohui

    2014-01-01

    Highlights: • Various morphologies of CeO 2 are gotten by controlling the solvothermal conditions. • The various morphologies are synthesized without any template or surfactant. • The chemical mechanisms for the formation of the products in the solvothermal process are discussed. • The morphology evolution from solid spheres to multilayered structures is supposed. • The as-synthesized CeO 2 samples possess excellent adsorption capacities. - Abstract: Ceria powders with different morphologies were synthesized using a facile template-free solvothermal process combined with calcination. The influence of solvothermal temperature and time on the powder was studied. Solid spheres, hollow spheres, and multilayered structures were controlled by adjusting the solvothermal conditions. The possible mechanisms for the formation of the precursors under the solvothermal conditions employed and the evolution of the powder from solid spherical to multilayered structures were discussed. Ethylene glycol played a key role in the morphology evolution of the powder. Cerium catalyzed the Guerbet-like reaction and reacted with ethylene glycol to produce ceria (CeO 2 ), Ce(HCOO) 3 , and Ce(OH)CO 3 . The redox-assisted dissolution–recrystallization process significantly contributed to the morphology transformation from solid spheres to multilayered structures. Moreover, the samples synthesized at different temperatures for 24 h possessed excellent adsorption capacities towards the removal of acid orange 7 when compared with commercial ceria

  2. Plasma generation using the hollow cathod

    International Nuclear Information System (INIS)

    Moon, K.J.

    1983-01-01

    A hollow cathode of tungsten was adapted to an University of California, Berkely, LBL bucket ion source to investigate ion density fluctuations at the extractior grid. Fluctuations in plasma ion density are observed to range between 100kHz to 2 MHz. The observed fluctuation frequencies of plasma ion density are found to be inversely proportional to the square root of ion masses. It is guessed that the plasma fluctuation are also correlated with the hollow cathode length. (Author)

  3. Adsorption characteristics of activated carbon hollow fibers

    Directory of Open Access Journals (Sweden)

    B. V. Kaludjerović

    2009-01-01

    Full Text Available Carbon hollow fibers were prepared with regenerated cellulose or polysulfone hollow fibers by chemical activation using sodium phosphate dibasic followed by the carbonization process. The activation process increases the adsorption properties of fibers which is more prominent for active carbone fibers obtained from the cellulose precursor. Chemical activation with sodium phosphate dibasic produces an active carbon material with both mesopores and micropores.

  4. Hollow cathode for positive ion sources

    International Nuclear Information System (INIS)

    Schechter, D.E.; Kim, J.; Tsai, C.C.

    1979-01-01

    Development to incorporate hollow cathodes into high power ion sources for neutral beam injection systems is being pursued. Hollow tube LaB 6 -type cathodes, similar to a UCLA design, have been constructed and tested in several ORNL ion source configurations. Results of testing include arc discharge parameters of >1000 and 500 amps for 0.5 and 10 second pulse lengths, respectively. Details of cathode construction and additional performance results are discussed

  5. Hollow-duct radiation delivery system investigation

    Directory of Open Access Journals (Sweden)

    Kramer D.

    2013-05-01

    Full Text Available Investigation of hollow-duct structure for high-power laser-diode-array radiation delivery into the end-pumped large-aperture gain media is reported. A ray tracing method has been used to evaluate the performance of the structure designed for maximum transmission efficiency and output beam profile homogeneity. Variable hollow-duct lengths as well as emanating angles of laser-diode-array have been taken into account.

  6. Synthesis of Hollow CdS-TiO2 Microspheres with Enhanced Visible-Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Yuning Huo

    2012-01-01

    Full Text Available CdS-TiO2 composite photocatalyst in the shape of hollow microsphere was successfully synthesized via the hard-template preparation with polystyrene microspheres followed by ion-exchange approach. The hollow CdS-TiO2 microspheres significantly extended the light adsorption into visible light region, comparing to TiO2 microspheres. It led to much higher photocatalytic activities of hollow CdS-TiO2 microspheres than that of TiO2 during the photodegradation of rhodamine B under visible light irradiations. Furthermore, the well-remained hollow structure could achieve light multireflection within the interior cavities and the separation of photo-induced electrons and holes is efficient in CdS-TiO2, which were facilitated to improving the photoactivity.

  7. VMware vSphere design

    CERN Document Server

    Guthrie, Forbes

    2013-01-01

    Achieve the performance, scalability, and ROI your business needs What can you do at the start of a virtualization deployment to make things run more smoothly? If you plan, deploy, maintain, and optimize vSphere solutions in your company, this unique book provides keen insight and solutions. From hardware selection, network layout, and security considerations to storage and hypervisors, this book explains the design decisions you'll face and how to make the right choices. Written by two virtualization experts and packed with real-world strategies and examples, VMware v

  8. Biocompatible magnetic and molecular dual-targeting polyelectrolyte hybrid hollow microspheres for controlled drug release.

    Science.gov (United States)

    Du, Pengcheng; Zeng, Jin; Mu, Bin; Liu, Peng

    2013-05-06

    Well-defined biocompatible magnetic and molecular dual-targeting polyelectrolyte hybrid hollow microspheres have been accomplished via the layer-by-layer (LbL) self-assembly technique. The hybrid shell was fabricated by the electrostatic interaction between the polyelectrolyte cation, chitosan (CS), and the hybrid anion, citrate modified ferroferric oxide nanoparticles (Fe3O4-CA), onto the uniform polystyrene sulfonate microsphere templates. Then the magnetic hybrid core/shell composite particles were modified with a linear, functional poly(ethylene glycol) (PEG) monoterminated with a biotargeting molecule (folic acid (FA)). Afterward the dual targeting hybrid hollow microspheres were obtained after etching the templates by dialysis. The dual targeting hybrid hollow microspheres exhibit exciting pH response and stability in high salt-concentration media. Their pH-dependent controlled release of the drug molecule (anticancer drug, doxorubicin (DOX)) was also investigated in different human body fluids. As expected, the cell viability of the HepG2 cells which decreased more rapidly was treated by the FA modified hybrid hollow microspheres rather than the unmodified one in the in vitro study. The dual-targeting hybrid hollow microspheres demonstrate selective killing of the tumor cells. The precise magnetic and molecular targeting properties and pH-dependent controlled release offers promise for cancer treatment.

  9. Poisson denoising on the sphere

    Science.gov (United States)

    Schmitt, J.; Starck, J. L.; Fadili, J.; Grenier, I.; Casandjian, J. M.

    2009-08-01

    In the scope of the Fermi mission, Poisson noise removal should improve data quality and make source detection easier. This paper presents a method for Poisson data denoising on sphere, called Multi-Scale Variance Stabilizing Transform on Sphere (MS-VSTS). This method is based on a Variance Stabilizing Transform (VST), a transform which aims to stabilize a Poisson data set such that each stabilized sample has an (asymptotically) constant variance. In addition, for the VST used in the method, the transformed data are asymptotically Gaussian. Thus, MS-VSTS consists in decomposing the data into a sparse multi-scale dictionary (wavelets, curvelets, ridgelets...), and then applying a VST on the coefficients in order to get quasi-Gaussian stabilized coefficients. In this present article, the used multi-scale transform is the Isotropic Undecimated Wavelet Transform. Then, hypothesis tests are made to detect significant coefficients, and the denoised image is reconstructed with an iterative method based on Hybrid Steepest Descent (HST). The method is tested on simulated Fermi data.

  10. Inner-Sphere versus Outer-Sphere Coordination of BF4– in a NHC-Gold(I) Complex

    KAUST Repository

    Veenboer, Richard M. P.

    2017-07-20

    The role of counterions in chemistry mediated by gold complexes stretches much further than merely providing charge balance to cationic gold species. Interplay between their basicities and coordination strengths influences interactions with both the gold center and substrates in catalysis. Actual monogold(I) active species are generally believed to be monocoordinated species, formed from the abstraction or the decoordination of a second ligand from precursor complexes, but only a small amount of experimental evidence exists to underpin the existence of these transient species. The formation of a bench-stable neutral IPrCl-gold(I) tetrafluoroborate complex is reported herein. Experimental studies by X-ray diffraction analysis and NMR spectroscopy and theoretical studies by DFT calculations were conducted to determine the composition, structure, and behavior of this complex. The absence of an auxiliary ligand resulted in inner-sphere coordination of the counterion in the solid state. In solution, an equilibrium between two conformations was found with the counterion occupying inner-sphere and outer-sphere positions, respectively. Stoichiometric and catalytic reactivity studies with the tetrafluoroborate complex have been conducted. These confirmed the lability of the inner-sphere coordinating counterion that gives the IPrCl-gold(I) fragment behavior similar to that of related systems.

  11. Inner-Sphere versus Outer-Sphere Coordination of BF4– in a NHC-Gold(I) Complex

    KAUST Repository

    Veenboer, Richard M. P.; Collado, Alba; Dupuy, Sté phanie; Lebl, Tomas; Falivene, Laura; Cavallo, Luigi; Cordes, David B.; Slawin, Alexandra M. Z.; Cazin, Catherine S. J.; Nolan, Steven P.

    2017-01-01

    The role of counterions in chemistry mediated by gold complexes stretches much further than merely providing charge balance to cationic gold species. Interplay between their basicities and coordination strengths influences interactions with both the gold center and substrates in catalysis. Actual monogold(I) active species are generally believed to be monocoordinated species, formed from the abstraction or the decoordination of a second ligand from precursor complexes, but only a small amount of experimental evidence exists to underpin the existence of these transient species. The formation of a bench-stable neutral IPrCl-gold(I) tetrafluoroborate complex is reported herein. Experimental studies by X-ray diffraction analysis and NMR spectroscopy and theoretical studies by DFT calculations were conducted to determine the composition, structure, and behavior of this complex. The absence of an auxiliary ligand resulted in inner-sphere coordination of the counterion in the solid state. In solution, an equilibrium between two conformations was found with the counterion occupying inner-sphere and outer-sphere positions, respectively. Stoichiometric and catalytic reactivity studies with the tetrafluoroborate complex have been conducted. These confirmed the lability of the inner-sphere coordinating counterion that gives the IPrCl-gold(I) fragment behavior similar to that of related systems.

  12. Kerr Hollow Quarry Remediation Project

    International Nuclear Information System (INIS)

    Walker, K.L.

    1993-01-01

    The Kerr Hollow Quarry is a 3-acre flooded limestone quarry located near the Y-12 Facility on the Oak Ridge Reservation. The quarry was used in the 1940s as a source of construction material for the Department of Energy in Oak Ridge, Tennessee. Its use was discontinued in the early 1950s, and it was allowed to flood with water. The quarry presently has a maximum water depth of approximately 55 ft. During the period between the early 1950s until about 1988, the quarry was used for the treatment and disposal of a variety of materials including water-reactive, alkali metals, shock-sensitive chemicals, and compressed gas cylinders. For some of these materials, the treatment consisted of dropping the vessels containing the materials into the quarry from a high bluff located on one side of the quarry. The vessels were then punctured by gun shot, and the materials were allowed to react with the water and sink to the bottom of the quarry. Very few disposal records exist for the period from 1952 to 1962. The records after that time, from 1962 until 1988, indicate some 50 t of hazardous and nonhazardous materials were disposed of in the quarry. This report documents remediation efforts that have taken place at the quarry beginning in September 1990

  13. The Positive Freedom of the Public Sphere

    DEFF Research Database (Denmark)

    Hansen, Ejvind

    2015-01-01

    calls for new reflections on the possible relationship between media, public sphere and democracy. This paper argues that we should change the questions that are raised when we try to assess the public sphere. It is argued that the traditional (Enlightenment) focus upon negative liberties and the truth-value......The relationship between democracy and the media since the appearance of Habermas' major texts in the 1960s has been articulated through theories of the public sphere. The structure of the public sphere is significantly influenced by the communicative media, and the emergence of the internet thus...

  14. Enhanced microwave absorption properties of MnO{sub 2} hollow microspheres consisted of MnO{sub 2} nanoribbons synthesized by a facile hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan; Han, Bingqian; Chen, Nan; Deng, Dongyang; Guan, Hongtao [Department of Materials Science and Engineering, Yunnan University, 650091, Kunming (China); Wang, Yude, E-mail: ydwang@ynu.edu.cn [Department of Materials Science and Engineering, Yunnan University, 650091, Kunming (China); Yunnan Province Key Lab of Micro-Nano Materials and Technology, Yunnan University, 650091, Kunming (China)

    2016-08-15

    MnO{sub 2} hollow microspheres consisted of nanoribbons were successfully fabricated via a facile hydrothermal method with SiO{sub 2} sphere templates. The crystal structure, morphology and microwave absorption properties in X and Ku band of the as-synthesized samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and a vector network analyzer. The results show that the three-dimensional (3D) hollow microspheres are assembled by ultra thin and narrow one-dimensional (1D) nanoribbons. A rational process for the formation of hollow microspheres is proposed. The 3D MnO{sub 2} hollow microspheres possess improved dielectric and magnetic properties than the 1D nanoribbons prepared by the same procedures with the absence of SiO{sub 2} hard templates, which are closely related to their special nanostructures. The MnO{sub 2} microspheres also show much better microwave absorption properties in X (8–12 GHz) and Ku (12–18 GHz) microwave band compared with 1D MnO{sub 2} nanoribbons. The minimum reflection loss of −40 dB for hollow microsphere can be observed at 14.2 GHz and reflection loss below −10 dB is 3.5 GHz with a thickness of only 4 mm. The possible mechanism for the enhanced microwave absorption properties is also discussed. - Graphical abstract: MnO{sub 2} hollow microspheres composed of nanoribbons show the excellent microwave absorption properties in X and Ku band. - Highlights: • MnO{sub 2} hollow microspheres consisted of MnO{sub 2} nanoribbons were successfully prepared. • MnO{sub 2} hollow microspheres possess good microwave absorption performances. • The excellent microwave absorption properties are in X and Ku microwave band. • Electromagnetic impedance matching is great contribution to absorption properties.

  15. Synthesis and characterization hollow spherical La0.7Sr0.2Ca0.1Co0.9Fe0.1O3–δ (LSCCT for cathode of solid oxide fuel cell (SOFC

    Directory of Open Access Journals (Sweden)

    H. H. Yu

    2016-10-01

    Full Text Available Hollow spheres structures of La0.7Sr0.2Ca0.1Co0.9Fe0.1O3–δ (LSCCT have been synthesized via hydrothermal method using carbon spheres as template. The structure and electrical conductivity of obtained samples are characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM and direct current (DC four-probe method respectively. The results show that hollow spheres structures of LSCCT with the mean particle size of 0,9 - 1,2 μm is single perovskite. The electrical conductivity of the samples is higher than 100 S/cm from 600 to 800 ℃ and can meet the demand of the electrical properties for the cathode materials.

  16. Sphere Rényi entropies

    International Nuclear Information System (INIS)

    Dowker, J S

    2013-01-01

    I give some scalar field theory calculations on a d-dimensional lune of arbitrary angle, evaluating, numerically, the effective action which is expressed as a simple quadrature, for conformal coupling. Using this, the entanglement and Rényi entropies are computed. Massive fields are also considered and a renormalization to make the (one-loop) effective action vanish for infinite mass is suggested and used, not entirely successfully. However a universal coefficient is derived from the large mass expansion. From the deformation of the corresponding lune result, I conjecture that the effective action on all odd manifolds with a simple conical singularity has an extremum when the singularity disappears. For the round sphere, I show how to convert the quadrature form of the conformal Laplacian determinant into the more usual sum of Riemann ζ-functions (and log 2). (paper)

  17. Glass transition temperature of polymer nano-composites with polymer and filler interactions

    Science.gov (United States)

    Hagita, Katsumi; Takano, Hiroshi; Doi, Masao; Morita, Hiroshi

    2012-02-01

    We systematically studied versatile coarse-grained model (bead spring model) to describe filled polymer nano-composites for coarse-grained (Kremer-Grest model) molecular dynamics simulations. This model consists of long polymers, crosslink, and fillers. We used the hollow structure as the filler to describe rigid spherical fillers with small computing costs. Our filler model consists of surface particles of icosahedra fullerene structure C320 and a repulsive force from the center of the filler is applied to the surface particles in order to make a sphere and rigid. The filler's diameter is 12 times of beads of the polymers. As the first test of our model, we study temperature dependence of volumes of periodic boundary conditions under constant pressures through NPT constant Andersen algorithm. It is found that Glass transition temperature (Tg) decrease with increasing filler's volume fraction for the case of repulsive interaction between polymer and fillers and Tg weakly increase for attractive interaction.

  18. Rheological Studies of Komatiite Liquids by In-Situ Falling Sphere Viscometry

    Science.gov (United States)

    O Dwyer, L.; Lesher, C. E.; Baxter, G.; Clark, A.; Fuss, T.; Tangeman, J.; Wang, Y.

    2005-12-01

    The rheological properties of komatiite liquids at high pressures and temperatures are being investigated by the in situ falling sphere technique, using the T-25 multianvil apparatus at the GSECARS 13 ID-D-D beamline at the Advanced Photon Source, ANL. The refractory and fluid nature of komatiite and other ultramafic liquids relevant to the Earth's deep interior, presents unique challenges for this approach. To reduce the density contrast between the melt and the marker sphere, and thus increase the Stoke's travel time, we have begun testing various composite spheres composed of refractory silicates and metals. Two successful custom designs are zirconia silicate mantled by Pt and Pt mantled by forsterite. These custom spheres contain sufficient Pt to absorb x-rays, while containing sufficient low-density refractory silicate so that marker sphere densities are in the range of 4-6 g/cc. These relatively more buoyant spheres increase travel time. These custom spheres, together with Re or Pt marker spheres, have been used to determine the viscosity of Gorgona anhydrous komatiite around 1600 ° C between 3.5 and 6 GPa. Initial experiments yield viscosities of 2.8 Pa s at 3.5 GPa, 5.3 Pa s at 4.6 GPa and 7.6 Pa s at 6 GPa. The observed positive pressure dependence of viscosity is consistent with recent results on pyrolite composition liquids and suggests that the activation volume for highly depolymerized melts will be positive for at least upper mantle conditions. The development of low-density, x-ray detectable marker spheres has applications in studies of melt density, whereby in situ detection of sink-float behavior during heating and compression cycles may be possible.

  19. Geocosmos: mapping outer space into a hollow earth

    Energy Technology Data Exchange (ETDEWEB)

    Abdelkader, M.A. (Alexandria, Egypt)

    1983-04-01

    The authors regards the earth's surface as a sphere and applies a purely mathematical mapping taking outer space in the Copernican universe (C) into a hollow earth, Geocosmos (G). The enormous galaxies and other remote objects are mapped inside as microscopic objects, and the moon as by far the largest of the celestial objects, all of which revolve daily around the earth's axis. Straight rays of light are mapped as arcs of circles, so that all celestial phenomena appear to inside observers in G just as they do to outside observers in C. He next considers the hypothesis that, conversely, the actual universe is this finite G. Then there seems to be no way of testing this, except by drilling a hole right through the earth's centre. However, in C the origin of cosmic rays of super-high energies is very controversial, whereas in G it is unequivocal. The idea of G was first conceived qualitatively by Karl E. Neupert in 1900; this revival is somewhat different. The main appeal of G stems from the very grave difficulty of believing in the fantastic vastness of C, and the consequent reduction of the earth to an infinitesimal.

  20. A geocosmos: mapping outer space into a hollow earth

    International Nuclear Information System (INIS)

    Abdelkader, M.A.

    1983-01-01

    The authors regards the earth's surface as a sphere and applies a purely mathematical mapping taking outer space in the Copernican universe (C) into a hollow earth, Geocosmos (G). The enormous galaxies and other remote objects are mapped inside as microscopic objects, and the moon as by far the largest of the celestial objects, all of which revolve daily around the earth's axis. Straight rays of light are mapped as arcs of circles, so that all celestial phenomena appear to inside observers in G just as they do to outside observers in C. He next considers the hypothesis that, conversely, the actual universe is this finite G. Then there seems to be no way of testing this, except by drilling a hole right through the earth's centre. However, in C the origin of cosmic rays of super-high energies is very controversial, whereas in G it is unequivocal. The idea of G was first conceived qualitatively by Karl E. Neupert in 1900; this revival is somewhat different. The main appeal of G stems from the very grave difficulty of believing in the fantastic vastness of C, and the consequent reduction of the earth to an infinitesimal. (Auth.)

  1. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2014-01-01

    Cue Rondo is an open composition to be realised by improvising musicians. See more about my composition practise in the entry "Composition - General Introduction". Caution: streaming the sound/video files will in some cases only provide a few minutes' sample, or the visuals will not appear at all....... Please DOWNLOAD them to see/hear them in full length! This work is licensed under a Creative Commons "by-nc" License. You may for non-commercial purposes use and distribute it, performance instructions as well as specially designated recordings, as long as the author is mentioned. Please see http...

  2. Hollow Mill for Extraction of Stripped Titanium Screws: An Easy ...

    African Journals Online (AJOL)

    countries. The known alternative in such condition is ... Key words: Hollow mill, stripped screws, titanium locked plates ... used a locally manufactured stainless steel hollow mill, ... head ‑ plate hole” assembly as a mono‑block single unit. In.

  3. Method for the production of fabricated hollow microspheroids

    Science.gov (United States)

    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.

  4. Electric dipoles on the Bloch sphere

    OpenAIRE

    Vutha, Amar C.

    2014-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic & molecular physics.

  5. Reversible thermal gelation in soft spheres

    DEFF Research Database (Denmark)

    Kapnistos, M.; Vlassopoulos, D.; Fytas, G.

    2000-01-01

    Upon heating, concentrated solutions of star polymers and block copolymer micelles in a good solvent, representing soft spheres, undergo a reversible gelation. This phenomenon is attributed to the formation of clusters causing a partial dynamic arrest of the swollen interpenetrating spheres at hi...

  6. Electric dipoles on the Bloch sphere

    International Nuclear Information System (INIS)

    Vutha, Amar C

    2015-01-01

    The time evolution of a two-level quantum mechanical system can be geometrically described using the Bloch sphere. By mapping the Bloch sphere evolution onto the dynamics of oscillating electric dipoles, we provide a physically intuitive link between classical electromagnetism and the electric dipole transitions of atomic and molecular physics. (paper)

  7. Potential of Hollow Glass Microsphere as Cement Replacement for Lightweight Foam Concrete on Thermal Insulation Performance

    Directory of Open Access Journals (Sweden)

    Shahidan Shahiron

    2017-01-01

    Full Text Available Global warming can be defined as a gradual increase in the overall temperature of the earth’s atmosphere. A lot of research work has been carried out to reduce that heat inside the residence such as the used of low density products which can reduce the self-weight, foundation size and construction costs. Foamed concrete it possesses high flow ability, low self-weight, minimal consumption of aggregate, controlled low strength and excellent thermal insulation properties. This study investigate the characteristics of lightweight foamed concrete where Portland cement (OPC was replaced by hollow glass microsphere (HGMs at 0%, 3%, 6%, 9% by weight. The density of wet concrete is 1000 kg/m3 were tested with a ratio of 0.55 for all water binder mixture. Lightweight foamed concrete hollow glass microsphere (HGMs produced were cured by air curing and water curing in tank for 7, 14 and 28 days. A total of 52 concrete cubes of size 100mm × 100mm × 100mm and 215mm × 102.5mm × 65mm were produced. Furthermore, Scanning Electron Microscope (SEM and X-ray fluorescence (XRF were carried out to study the chemical composition and physical properties of crystalline materials in hollow glass microspheres. The experiments involved in this study are compression strength, water absorption test, density and thermal insulation test. The results show that the compressive strength of foamed concrete has reached the highest in 3% of hollow glass microsphere with less water absorption and less of thermal insulation. As a conclusion, the quantity of hollow glass microsphere plays an important role in determining the strength and water absorption and also thermal insulation in foamed concrete and 3% hollow glass microspheres as a replacement for Portland cement (OPC showed an optimum value in this study as it presents a significant effect than other percentage.

  8. Development of tree hollows in pedunculate oak (Quercus robur)

    OpenAIRE

    Ranius, Thomas; Niklasson, Mats; Berg, Niclas

    2009-01-01

    Many invertebrates, birds and mammals are dependent on hollow trees. For landscape planning that aims at persistence of species inhabiting hollow trees it is crucial to understand the development of such trees. In this study we constructed an individual-based simulation model to predict diameter distribution and formation of hollows in oak tree populations. Based on tree-ring data from individual trees, we estimated the ages when hollow formation commences for pedunculate oak (Quercus robur) ...

  9. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  10. Adiabatic Rearrangement of Hollow PV Towers

    Directory of Open Access Journals (Sweden)

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  11. Properties of dry masonry mixtures based on hollow aluminosilicate microspheres

    Directory of Open Access Journals (Sweden)

    Semenov Vyacheslav

    2017-01-01

    Full Text Available At present, there is a steady increase in the volume of housing construction in the Russian Federation. The modern trends in the field of energy and resource saving determine the need of the use of efficient building materials that ensure the safety, comfort and minimum cost of housing construction. Among the materials, often used for erecting of fencing structures, it is possible to note effective small-piece elements (ceramic and light-weight concrete units, etc.. To ensure the solidity of such structures, it is necessary to use the masonry mortars whose properties correspond to those of the main wall material. The existing dry mixes for obtaining of such mortars are expensive and often do not meet the minimum physical-and-mechanical and exploitation requirements. The solution of this problem is the usage of the hollow ceramics (aluminosilicate microspheres as a filler for such mixes. The article presents the results of studies of the main physical-and-mechanical and exploitation characteristics of dry masonry mixes with hollow ceramics microspheres modified with various chemical additives. The effect of the compounding factors on the average density and strength of dry masonry mixes was studied. The compositions have been optimized by the methods of mathematical planning.

  12. Studies on pulsed hollow cathode capillary discharges

    Energy Technology Data Exchange (ETDEWEB)

    Choi, P; Dumitrescu-Zoita, C; Larour, J; Rous, J [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises; Favre, M; Moreno, J; Chuaqui, H; Wyndham, E [Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Zambra, M [Comision Chilena de Energia Nuclear, Santiago (Chile); Wong, C S [Univ. of Malaya, Kuala Lumpur (Malaysia). Plasma Research Lab

    1997-12-31

    Preliminary results on radiation characteristics of pulsed hollow cathode capillary discharges are presented. The device combines the on axis electron beam assisted ionization capabilities of the transient hollow cathode discharge with a novel high voltage low inductance geometrical design, which integrates the local energy storage into the electrode system. A nanosecond regime high temperature plasma is produced in a long, high aspect ratio capillary, with light emission in the UV to XUV region. The discharge is operated from near vacuum to pressure in the 1000 mTorr range. (author). 2 figs., 7 refs.

  13. Microfabricated hollow microneedle array using ICP etcher

    Science.gov (United States)

    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.

  14. Microfabricated hollow microneedle array using ICP etcher

    International Nuclear Information System (INIS)

    Ji Jing; Tay, Francis E H; Miao Jianmin

    2006-01-01

    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 SF 6 /O 2 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

  15. Microfabricated hollow microneedle array using ICP etcher

    Energy Technology Data Exchange (ETDEWEB)

    Ji Jing [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Tay, Francis E H [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Miao Jianmin [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    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 SF{sub 6}/O{sub 2} 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.

  16. Computational predictions of zinc oxide hollow structures

    Science.gov (United States)

    Tuoc, Vu Ngoc; Huan, Tran Doan; Thao, Nguyen Thi

    2018-03-01

    Nanoporous materials are emerging as potential candidates for a wide range of technological applications in environment, electronic, and optoelectronics, to name just a few. Within this active research area, experimental works are predominant while theoretical/computational prediction and study of these materials face some intrinsic challenges, one of them is how to predict porous structures. We propose a computationally and technically feasible approach for predicting zinc oxide structures with hollows at the nano scale. The designed zinc oxide hollow structures are studied with computations using the density functional tight binding and conventional density functional theory methods, revealing a variety of promising mechanical and electronic properties, which can potentially find future realistic applications.

  17. Preparation of hollow microspheres of Ce{sup 3+} doped NiCo ferrite with high microwave absorbing performance

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hong-zhen, E-mail: duanhz2000@163.com; Zhou, Fang-ling; Cheng, Xia; Chen, Guo-hong; Li, Qiao-ling

    2017-02-15

    Hollow microspheres of Ce{sup 3+} doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method with carbon sphere as the template. The phase structure, morphology, magnetic properties and wave absorbing properties of the sample were characterized by X-ray powder diffraction(XRD), Scanning electronic microscopy(SEM), Vibration sample magnetometer (VSM) and a network vector analyzer (NVA), respectively. The results indicated that the particle size of the carbon sphere sample prepared by hydrothermal method was about 0.5 µm and the particle size of the Ni{sub 0.5}Co{sub 0.5}Fe{sub 2}O{sub 4} sample prepared by template-based method was about 300 nm. The influence of the amount of rare earth element on the magnetic and absorbing properties of sample was studied. The saturation magnetization and coercivity decreased gradually with the increase of the content of Ce. When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu• g{sup −1} and 789.88 Oe, respectively. The associated ferrite hollow spheres have good absorbing performance, and the return loss value was −18.8 dB at 5500 MHz. - Highlights: • Hollow microspheres of Ce{sup 3+} doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method. • The influence of rare earth Ce{sup 3+} on the magnetic and absorbing properties of sample was studied. • When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu• g{sup −1} and 789.88 Oe, respectively.

  18. Self-assembly of hollow MoS{sub 2} microflakes by one-pot hydrothermal synthesis for efficient electrocatalytic hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Aishi; Cui, Renjie; He, Yanna; Wang, Qi [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); Zhang, Jian, E-mail: iamjzhang@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); Yang, Jianping [School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023 (China); Li, Xing’ao, E-mail: lxahbmy@126.com [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023 (China)

    2017-07-31

    Highlights: • A new hollow MoS{sub 2} microflakes are prepared by hydrothermal synthesis firstly. • SEM and TEM study show the structural nature of hollow microflakes in depth. • The unique hollow structures have large surface area owing to the cavity. • The hollow microflakes show better HER performance than their solid counterparts. - Abstract: Molybdenum disulfide (MoS{sub 2}) has emerged as a promising non-precious metal catalyst for hydrogen evolution reaction (HER) in recent years. Some strategies including nanotechnology as well as atom doping have been employed in the preparing of electrocatalysts for high-activity and stability. To the best of our knowledge, hollow MoS{sub 2} microflakes assembled from ultrathin nanosheets have not been prepared previously. In this work, a simple, facile and environmentally friendly hydrothermal synthesis was utilized for the fabrication of hollow MoS{sub 2} microflakes for the first time. The unique hollow structures have fascinating properties, such as the large surface and low density. The morphology and structure of MoS{sub 2} microflakes were confirmed by XRD, SEM, TEM and Raman. The composition of these materials was identified by the X-ray photoelectron spectroscopy. Notably, the as-prepared hollow MoS{sub 2} microflakes showed better electrocatalytic activity than other samples. The hollow flake-like structure can not only increase the active edge sites owing to the large specific surface area, but also enhance the electron transport to improve the electrocatalytic activity. Benefiting from these factors, the hollow MoS{sub 2} microflakes exhibited electrocatalytic activity and excellent stability with a low overpotential about 85 mV and a Tafel slope of 59 mV per decade.

  19. Anomalies, conformal manifolds, and spheres

    Energy Technology Data Exchange (ETDEWEB)

    Gomis, Jaume [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada); Hsin, Po-Shen [Department of Physics, Princeton University,Princeton, NJ 08544 (United States); Komargodski, Zohar; Schwimmer, Adam [Weizmann Institute of Science,Rehovot 76100 (Israel); Seiberg, Nathan [School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States); Theisen, Stefan [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,14476 Golm (Germany)

    2016-03-04

    The two-point function of exactly marginal operators leads to a universal contribution to the trace anomaly in even dimensions. We study aspects of this trace anomaly, emphasizing its interpretation as a sigma model, whose target space M is the space of conformal field theories (a.k.a. the conformal manifold). When the underlying quantum field theory is supersymmetric, this sigma model has to be appropriately supersymmetrized. As examples, we consider in some detail N=(2,2) and N=(0,2) supersymmetric theories in d=2 and N=2 supersymmetric theories in d=4. This reasoning leads to new information about the conformal manifolds of these theories, for example, we show that the manifold is Kähler-Hodge and we further argue that it has vanishing Kähler class. For N=(2,2) theories in d=2 and N=2 theories in d=4 we also show that the relation between the sphere partition function and the Kähler potential of M follows immediately from the appropriate sigma models that we construct. Along the way we find several examples of potential trace anomalies that obey the Wess-Zumino consistency conditions, but can be ruled out by a more detailed analysis.

  20. Theorising Public and Private Spheres

    Directory of Open Access Journals (Sweden)

    Sima Remina

    2016-12-01

    Full Text Available The 19th century saw an expression of women’s ardent desire for freedom, emancipation and assertion in the public space. Women hardly managed to assert themselves at all in the public sphere, as any deviation from their traditional role was seen as unnatural. The human soul knows no gender distinctions, so we can say that women face the same desire for fulfillment as men do. Today, women are more and more encouraged to develop their skills by undertaking activities within the public space that are different from those that form part of traditional domestic chores. The woman of the 19th century felt the need to be useful to society, to make her contribution visible in a variety of domains. A woman does not have to become masculine to get power. If she is successful in any important job, this does not mean that she thinks like a man, but that she thinks like a woman. Women have broken through the walls that cut them off from public life, activity and ambition. There are no hindrances that can prevent women from taking their place in society.

  1. In-situ sulfuration synthesis of sandwiched spherical tin sulfide/sulfur-doped graphene composite with ultra-low sulfur content

    Science.gov (United States)

    Zhao, Bing; Yang, Yaqing; Wang, Zhixuan; Huang, Shoushuang; Wang, Yanyan; Wang, Shanshan; Chen, Zhiwen; Jiang, Yong

    2018-02-01

    SnS is widely studied as anode materials since of its superior structural stability and physicochemical property comparing with other Sn-based composites. Nevertheless, the inconvenience of phase morphology control and excessive consumption of sulfur sources during synthesis hinder the scalable application of SnS nanocomposites. Herein, we report a facile in-situ sulfuration strategy to synthesize sandwiched spherical SnS/sulfur-doped graphene (SnS/S-SG) composite. An ultra-low sulfur content with approximately stoichiometric ratio of Sn:S can effectively promote the sulfuration reaction of SnO2 to SnS and simultaneous sulfur-doping of graphene. The as-prepared SnS/S-SG composite shows a three-dimensional interconnected spherical structure as a whole, in which SnS nanoparticles are sandwiched between the multilayers of graphene sheets forming a hollow sphere. The sandwiched sphere structure and high S doping amount can improve the binding force between SnS and graphene, as well as the structural stability and electrical conductivity of the composite. Thus, a high reversibility of conversion reaction, promising specific capacity (772 mAh g-1 after 100 cycles at 0.1 C) and excellent rate performance (705 and 411 mAh g-1 at 1 C and 10 C, respectively) are exhibited in the SnS/S-SG electrode, which are much higher than that of the SnS/spherical graphene synthesized by traditional post-sulfuration method.

  2. TWO FERROMAGNETIC SPHERES IN HOMOGENEOUS MAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    Yury A. Krasnitsky

    2018-01-01

    Full Text Available The problem of two spherical conductors is studied quite in detail with bispherical coordinates usage and has numerous appendices in an electrostatics. The boundary-value problem about two ferromagnetic spheres enclosed on homogeneous and infinite environment in which the lack of spheres exists like homogeneous magnetic field is considered. The solution of Laplace's equation in the bispherical system of coordinates allows us to find the potential and field distribution in all spaces, including area between spheres. The boundary conditions in potential continuity and in ordinary density constituent of spheres surfaces induction flux are used. It is supposed that spheres are identical, and magnetic permeability of their material is expressed in  >> 0. The problem about falling of electromagnetic plane wave on the system of two spheres, which possesses electrically small sizes, can be considered as quasistationary. The scalar potentials received as a result of Laplace's equation solution are represented by the series containing Legendre polynomials. The concept of two spheres system effective permeability is introduced. It is equal to the advantage in magnitude of magnetic induction flux vector through a certain system’s section arising due to its magnetic properties. Necessary ratios for the effective permeability referred to the central system’s section are obtained. Particularly, the results can be used during the analysis of ferroxcube core clearance, which influences on the magnetic antenna properties. 

  3. Unsteady flow over a decelerating rotating sphere

    Science.gov (United States)

    Turkyilmazoglu, M.

    2018-03-01

    Unsteady flow analysis induced by a decelerating rotating sphere is the main concern of this paper. A revolving sphere in a still fluid is supposed to slow down at an angular velocity rate that is inversely proportional to time. The governing partial differential equations of motion are scaled in accordance with the literature, reducing to the well-documented von Kármán equations in the special circumstance near the pole. Both numerical and perturbation approaches are pursued to identify the velocity fields, shear stresses, and suction velocity far above the sphere. It is detected that an induced flow surrounding the sphere acts accordingly to adapt to the motion of the sphere up to some critical unsteadiness parameters at certain latitudes. Afterward, the decay rate of rotation ceases such that the flow at the remaining azimuths starts revolving freely. At a critical unsteadiness parameter corresponding to s = -0.681, the decelerating sphere rotates freely and requires no more torque. At a value of s exactly matching the rotating disk flow at the pole identified in the literature, the entire flow field around the sphere starts revolving faster than the disk itself. Increasing values of -s almost diminish the radial outflow. This results in jet flows in both the latitudinal and meridional directions, concentrated near the wall region. The presented mean flow results will be useful for analyzing the instability features of the flow, whether of a convective or absolute nature.

  4. Molecular motor transport through hollow nanowires

    DEFF Research Database (Denmark)

    Lard, Mercy; Ten Siethoff, Lasse; Generosi, Johanna

    2014-01-01

    -driven motion of fluorescent probes (actin filaments) through 80 nm wide, Al2O 3 hollow nanowires of micrometer length. The motor-driven transport is orders of magnitude faster than would be possible by passive diffusion. The system represents a necessary element for advanced devices based on gliding assays...

  5. Hollow micro string based calorimeter device

    DEFF Research Database (Denmark)

    2014-01-01

    positions so as to form a free released double clamped string in-between said two longitudinally distanced positions said micro-channel string comprising a microfluidic channel having a closed cross section and extending in the longitudinal direction of the hollow string, acoustical means adapted...

  6. Hollow fibre supported liquid membrane extraction of ...

    African Journals Online (AJOL)

    A simple sample pre-treatment method utilizing hollow fibre supported liquid membrane (HFSLM) was carried out on pharmaceuticals samples comprising of cough syrups (CS1 and CS2) and an anti-inflammatory product (AI). The active ingredients targeted in the extraction process were diphenylhydramine (DPH), ...

  7. Finding a source inside a sphere

    International Nuclear Information System (INIS)

    Tsitsas, N L; Martin, P A

    2012-01-01

    A sphere excited by an interior point source or a point dipole gives a simplified yet realistic model for studying a variety of applications in medical imaging. We suppose that there is an exterior field (transmission problem) and that the total field on the sphere is known. We give analytical inversion algorithms for determining the interior physical characteristics of the sphere as well as the location, strength and orientation of the source/dipole. We start with static problems (Laplace’s equation) and then proceed to acoustic problems (Helmholtz equation). (paper)

  8. Core–Shell Electrospun Hollow Aluminum Oxide Ceramic Fibers

    Directory of Open Access Journals (Sweden)

    Jonathan W. Rajala

    2015-10-01

    Full Text Available In this work, core–shell electrospinning was employed as a simple method for the fabrication of composite coaxial polymer fibers that became hollow ceramic tubes when calcined at high temperature. The shell polymer solution consisted of polyvinyl pyrollidone (PVP in ethanol mixed with an aluminum acetate solution to act as a ceramic precursor. The core polymer was recycled polystyrene to act as a sacrificial polymer that burned off during calcination. The resulting fibers were analyzed with X-ray diffraction (XRD and energy dispersive spectroscopy (EDS to confirm the presence of gamma-phase aluminum oxide when heated at temperatures above 700 °C. The fiber diameter decreased from 987 ± 19 nm to 382 ± 152 nm after the calcination process due to the polymer material being burned off. The wall thickness of these fibers is estimated to be 100 nm.

  9. Preparation of Well-Dispersed Chitosan/Alginate Hollow Multilayered Microcapsules for Enhanced Cellular Internalization

    Directory of Open Access Journals (Sweden)

    Carla Ribeiro

    2018-03-01

    Full Text Available Hollow multilayered capsules have shown massive potential for being used in the biomedical and biotechnology fields, in applications such as cellular internalization, intracellular trafficking, drug delivery, or tissue engineering. In particular, hollow microcapsules, developed by resorting to porous calcium carbonate sacrificial templates, natural-origin building blocks and the prominent Layer-by-Layer (LbL technology, have attracted increasing attention owing to their key features. However, these microcapsules revealed a great tendency to aggregate, which represents a major hurdle when aiming for cellular internalization and intracellular therapeutics delivery. Herein, we report the preparation of well-dispersed polysaccharide-based hollow multilayered microcapsules by combining the LbL technique with an optimized purification process. Cationic chitosan (CHT and anionic alginate (ALG were chosen as the marine origin polysaccharides due to their biocompatibility and structural similarity to the extracellular matrices of living tissues. Moreover, the inexpensive and highly versatile LbL technology was used to fabricate core-shell microparticles and hollow multilayered microcapsules, with precise control over their composition and physicochemical properties, by repeating the alternate deposition of both materials. The microcapsules’ synthesis procedure was optimized to extensively reduce their natural aggregation tendency, as shown by the morphological analysis monitored by advanced microscopy techniques. The well-dispersed microcapsules showed an enhanced uptake by fibroblasts, opening new perspectives for cellular internalization.

  10. Study on surface adhesion of Plasma modified Polytetrafluoroethylene hollow fiber membrane

    Science.gov (United States)

    Chen, Jiangrong; Zhang, Huifeng; Liu, Guochang; Guo, Chungang; Lv, Jinglie; Zhangb, Yushan

    2018-01-01

    Polytetrafluoroethylene (PTFE) is popular membrane material because of its excellent thermal stability, chemical stability and mechanical stability. However, the low surface energy and non-sticky property of PTFE present challenges for modification. In the present study, plasma treatment was performed to improve the surface adhesion of PTFE hollow fiber membrane. The effect of discharge voltage, treatment time on the adhesion of PTFE hollow fiber membrane was symmetrically evaluated. Results showed that the plasma treatment method contributed to improve the surface activity and roughness of PTFE hollow fiber membrane, and the adhesion strength depend significantly on discharge voltage, which was beneficial to seepage pressure of PTFE hollow fiber membrane module. The adhesion strength of PTFE membrane by plasma treated at 220V for 3min reached as high as 86.2 N, far surpassing the adhesion strength 12.7 N of pristine membrane. Furthermore, improvement of content of free radical and composition analysis changes of the plasma modified PTFE membrane were investigated. The seepage pressure of PTFE membrane by plasma treated at 220V for 3min was 0.375 MPa, which means that the plasma treatment is an effective technique to improve the adhesion strength of membrane.

  11. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible......Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...

  12. On the subtle balance between competitive sorption and plasticization effects in asymmetric hollow fiber gas separation membranes

    NARCIS (Netherlands)

    Visser, Tymen; Koops, G.H.; Wessling, Matthias

    2005-01-01

    The paper describes the influence of a varying feed composition of CO2/CH4 and CO2/N2 mixtures on the gas separation performance of integrally skinned asymmetric PES/PI hollow fibers with an effective skin thickness of 0.27 ¿m. Normally, thin membrane structures (<3 ¿m) show accelerated

  13. Synthesis and upconversion luminescence properties of YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers derived from Y{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Li Dan; Dong Xiangting, E-mail: dongxiangting888@163.com; Yu Wensheng; Wang Jinxian; Liu Guixia [Changchun University of Science and Technology, Key Laboratory of Applied Chemistry and Nanotechnology at Universities of Jilin Province (China)

    2013-06-15

    YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers were successfully fabricated via fluorination of the relevant Y{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO{sub 3}){sub 3} + Yb(NO{sub 3}){sub 3} + Er(NO{sub 3}){sub 3}] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction, scanning electron microscope, transmission electron microscope, and fluorescence spectrometer. YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with mean diameter of 174 {+-} 22 nm, and YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers are composed of nanoparticles with size in the range of 30-60 nm. Upconversion emission spectrum analysis manifested that YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers emitted strong green and weak red upconversion emissions centering at 523, 545, and 654 nm, respectively. The green and red emissions were, respectively, originated from {sup 2}H{sub 11/2}/{sup 4}S{sub 3/2} {yields} {sup 4}I{sub 15/2} and {sup 4}F{sub 9/2} {yields} {sup 4}I{sub l5/2} energy levels transitions of the Er{sup 3+} ions. Moreover, the emitting colors of YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers.Graphical AbstractYF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers with orthorhombic structure were synthesized by fluorination of the electrospun Y{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers via a double-crucible method using NH{sub 4}HF{sub 2} as fluorinating agent. The mean diameter of YF{sub 3}:Yb{sup 3+}/Er{sup 3+} hollow nanofibers was 174 {+-} 22 nm. The fluorination method we proposed here has been proved to be an important method, as it can not only

  14. Acoustic levitation of a large solid sphere

    Science.gov (United States)

    Andrade, Marco A. B.; Bernassau, Anne L.; Adamowski, Julio C.

    2016-07-01

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.

  15. Acoustic levitation of a large solid sphere

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Marco A. B., E-mail: marcobrizzotti@gmail.com [Institute of Physics, University of São Paulo, São Paulo 05508-090 (Brazil); Bernassau, Anne L. [School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Adamowski, Julio C. [Department of Mechatronics and Mechanical Systems Engineering, Escola Politécnica, University of São Paulo, São Paulo 05508-030 (Brazil)

    2016-07-25

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.

  16. Spheres of SA Government, responsibilities and delivery

    CSIR Research Space (South Africa)

    Oelofse, Suzanna HH

    2010-09-01

    Full Text Available The institutional framework for government in South Africa was established in 1996 with the adoption of the first democratic Constitution. National, provincial and local government was established as three elected spheres of government, each...

  17. Gender, Diversity and the European Public Sphere

    DEFF Research Database (Denmark)

    Pristed Nielsen, Helene

    2009-01-01

    This paper argues that feminist criticism of Habermasian theory leads to new ways of approaching empirical analyses of public sphere deliberation, and gives some concrete indications of which methodological consequences such a critique may lead to....

  18. Hydrodynamic interaction between bacteria and passive sphere

    Science.gov (United States)

    Zhang, Bokai; Ding, Yang; Xu, Xinliang

    2017-11-01

    Understanding hydrodynamic interaction between bacteria and passive sphere is important for identifying rheological properties of bacterial and colloidal suspension. Over the past few years, scientists mainly focused on bacterial influences on tracer particle diffusion or hydrodynamic capture of a bacteria around stationary boundary. Here, we use superposition of singularities and regularized method to study changes in bacterial swimming velocity and passive sphere diffusion, simultaneously. On this basis, we present a simple two-bead model that gives a unified interpretation of passive sphere diffusion and bacterial swimming. The model attributes both variation of passive sphere diffusion and changes of speed of bacteria to an effective mobility. Using the effective mobility of bacterial head and tail as an input function, the calculations are consistent with simulation results at a broad range of tracer diameters, incident angles and bacterial shapes.

  19. Acoustic levitation of a large solid sphere

    International Nuclear Information System (INIS)

    Andrade, Marco A. B.; Bernassau, Anne L.; Adamowski, Julio C.

    2016-01-01

    We demonstrate that acoustic levitation can levitate spherical objects much larger than the acoustic wavelength in air. The acoustic levitation of an expanded polystyrene sphere of 50 mm in diameter, corresponding to 3.6 times the wavelength, is achieved by using three 25 kHz ultrasonic transducers arranged in a tripod fashion. In this configuration, a standing wave is created between the transducers and the sphere. The axial acoustic radiation force generated by each transducer on the sphere was modeled numerically as a function of the distance between the sphere and the transducer. The theoretical acoustic radiation force was verified experimentally in a setup consisting of an electronic scale and an ultrasonic transducer mounted on a motorized linear stage. The comparison between the numerical and experimental acoustic radiation forces presents a good agreement.

  20. 1-Public sphere Ambadiang.pmd

    African Journals Online (AJOL)

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    2011-03-09

    Mar 9, 2011 ... Council for the Development of Social Science Research in Africa, 2010 .... Ambadiang: Public Sphere, Linguistic Sphericules and Discourse Communities in Africa ...... eds., Media, Ritual, Identity, London: Routledge, pp.