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Sample records for colloid-stable nanosized selective

  1. Colloid stable sorbents for cesium removal: preparation and application of latex particles functionalized with transition metals ferrocyanides.

    PubMed

    Avramenko, Valentin; Bratskaya, Svetlana; Zheleznov, Veniamin; Sheveleva, Irina; Voitenko, Oleg; Sergienko, Valentin

    2011-02-28

    In this paper we suggest a principally new approach to preparation of colloid stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid stable sorbents toward cesium ions were studied in solutions containing up to 200 g/L of sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.3-1.5 mol Cs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that made them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed. PMID:21208744

  2. Colloidally Stable and Surfactant-Free Protein-Coated Gold Nanorods in Biological Media

    PubMed Central

    2015-01-01

    In this work, we investigate the ligand exchange of cetyltrimethylammonium bromide (CTAB) with bovine serum albumin for gold nanorods. We demonstrate by surface-enhanced Raman scattering measurements that CTAB, which is used as a shape-directing agent in the particle synthesis, is completely removed from solution and particle surface. Thus, the protein-coated nanorods are suitable for bioapplications, where cationic surfactants must be avoided. At the same time, the colloidal stability of the system is significantly increased, as evidenced by spectroscopic investigation of the particle longitudinal surface plasmon resonance, which is sensitive to aggregation. Particles are stable at very high concentrations (cAu 20 mg/mL) in biological media such as phosphate buffer saline or Dulbecco’s Modified Eagle’s Medium and over a large pH range (2–12). Particles can even be freeze-dried (lyophilized) and redispersed. The protocol was applied to gold nanoparticles with a large range of aspect ratios and sizes with main absorption frequencies covering the visible and the near-IR spectral range from 600 to 1100 nm. Thus, these colloidally stable and surfactant-free protein-coated nanoparticles are of great interest for various plasmonic and biomedical applications. PMID:25706195

  3. Synthesis and Size-Separation of Colloidally-Stable Silicon Nanocrystals for the Investigation of their Size-Dependent Optical Properties

    NASA Astrophysics Data System (ADS)

    Mastronardi, Melanie

    Silicon nanocrystals (ncSi) possess unique optical properties that vary predictably with crystal size, which means they can be tailored to suit specific requirements for use in optoelectronic devices and biological applications. The work presented in this thesis outlines contributions made in developing size-separation methods to obtain uniform-sized samples of colloidally-stable ncSi from non-uniform ensembles, which result from most common syntheses that produce colloidally-stable particles. Non-uniform samples of ncSi were prepared using the straightforward thermal processing of sol-gel glasses, followed by HF etching to liberate hydride-capped ncSi from an encapsulating matrix. Thermal hydrosilylation was employed to passivate the ncSi surface with both allylbenzene and 1-decene. Density gradient ultracentrifugation and size-selective precipitation methods were used to isolate size-separated ncSi, which enabled definitive characterization of size-dependent optical properties including photoluminescence (PL), PL absolute quantum yields, and PL lifetimes. A detailed investigation of the chemical reactivity of allylbenzene-capped ncSi with different gaseous atmospheres as probed by in situ luminescence spectroscopy, conducted under both continuous and intermittent illumination, helped elucidate the roles of O2, H2O and mixtures of O2/H 2O, with respect to oxidation of ncSi as a function of size. The results presented in this thesis have played a crucial role towards obtaining a complete understanding of ncSi, a most promising material, and providing vital information that will aid in developing and tailoring perceived applications in advanced materials and biomedical devices.

  4. Synthesis of nanosized sodium titanates

    DOEpatents

    Hobbs, David T.; Taylor-Pashow, Kathryn M. L.; Elvington, Mark C.

    2015-09-29

    Methods directed to the synthesis and peroxide-modification of nanosized monosodium titanate are described. Methods include combination of reactants at a low concentration to a solution including a nonionic surfactant. The nanosized monosodium titanate can exhibit high selectivity for sorbing various metallic ions.

  5. Toxicological aspects of photocatalytic degradation of selected xenobiotics with nano-sized Mn-doped TiO2.

    PubMed

    Ozmen, Murat; Güngördü, Abbas; Erdemoglu, Sema; Ozmen, Nesrin; Asilturk, Meltem

    2015-08-01

    The toxic effects of two selected xenobiotics, bisphenol A (BPA) and atrazine (ATZ), were evaluated after photocatalytic degradation using nano-sized, Mn-doped TiO2. Undoped and Mn-doped TiO2 nanoparticles were synthesized. The samples were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), UV-vis-diffuse reflectance spectra (DRS), X-ray fluorescence spectroscopy (XRF), and BET surface area. The photocatalytic efficiency of the undoped and Mn-doped TiO2 was evaluated for BPA and ATZ. The toxicity of the synthesized photocatalysts and photocatalytic by-products of BPA and ATZ was determined using frog embryos and tadpoles, zebrafish embryos, and bioluminescent bacteria. Possible toxic effects were also evaluated using selected enzyme biomarkers. The results showed that Mn-doped TiO2 nanoparticles did not cause significant lethality in Xenopus laevis embryos and tadpoles, but nonfiltered samples caused lethality in zebrafish. Furthermore, Mn-doping of TiO2 increased the photocatalytic degradation capability of nanoparticles, and it successfully degraded BPA and AZT, but degradation of AZT caused an increase of the lethal effects on both tadpoles and fish embryos. Degradation of BPA caused a significant reduction of lethal effects, especially after 2-4h of degradation. However, biochemical assays showed that both Mn-doped TiO2 and the degradation by-products caused a significant change of selected biomarkers on X. laevis tadpoles; thus, the ecological risks of Mn-doped TiO2 should be considered due to nanomaterial applications and for spilled nanoparticles in an aquatic ecosystem. Also, the risk of nanoparticles should be considered using indicator reference biochemical markers to verify the environmental health impacts. PMID:26037099

  6. Synthesis of nano-sized arsenic-imprinted polymer and its use as As(3+) selective ionophore in a potentiometric membrane electrode: part 1.

    PubMed

    Alizadeh, Taher; Rashedi, Mariyam

    2014-09-16

    In this study, a new strategy was proposed for the preparation of As (III)-imprinted polymer by using arsenic (methacrylate)3 as template. Precipitation polymerization was utilized to synthesize nano-sized As (III)-imprinted polymer. Methacrylic acid and ethylene glycol dimethacrylate were used as the functional monomer and cross-linking agent, respectively. In order to assembly functional monomers around As (III) ion, sodium arsenite and methacrylic acid were heated in the presence of hydroquinone, leading to arsenic (methacrylate)3. The nano-sized As (III) selective polymer was characterized by FT-IR and scanning electron microscopy techniques (SEM). It was demonstrated that arsenic was recognized as As(3+) by the selective cavities of the synthesized IIP. Based on the prepared polymer, the first arsenic cation selective membrane electrode was introduced. Membrane electrode was constructed by dispersion of As (III)-imprinted polymer nanoparticles in poly(vinyl chloride), plasticized with di-nonylphthalate. The IIP-modified electrode exhibited a Nernstian response (20.4±0.5 mV decade(-1)) to arsenic ion over a wide concentration range (7.0×10(-7) to 1.0×10(-1) mol L(-1)) with a lower detection limit of 5.0×10(-7) mol L(-1). Unlike this, the non-imprinted polymer (NIP)-based membrane electrode was not sensitive to arsenic in aqueous solution. The selectivity of the developed sensor to As (III) was shown to be satisfactory. The sensor was used for arsenic determination in some real samples. PMID:25150692

  7. Synthesis, structural characterization and selectively catalytic properties of metal-organic frameworks with nano-sized channels: A modular design strategy

    SciTech Connect

    Qiu Lingguang Gu Lina; Hu Gang; Zhang Lide

    2009-03-15

    Modular design method for designing and synthesizing microporous metal-organic frameworks (MOFs) with selective catalytical activity was described. MOFs with both nano-sized channels and potential catalytic activities could be obtained through self-assembly of a framework unit and a catalyst unit. By selecting hexaaquo metal complexes and the ligand BTC (BTC=1,3,5-benzenetricarboxylate) as framework-building blocks and using the metal complex [M(phen){sub 2}(H{sub 2}O){sub 2}]{sup 2+} (phen=1,10-phenanthroline) as a catalyst unit, a series of supramolecular MOFs 1-7 with three-dimensional nano-sized channels, i.e. [M{sup 1}(H{sub 2}O){sub 6}].[M{sup 2}(phen){sub 2}(H{sub 2}O){sub 2}]{sub 2}.2(BTC).xH{sub 2}O (M{sup 1}, M{sup 2}=Co(II), Ni(II), Cu(II), Zn(II), or Mn(II), phen=1,10-phenanthroline, BTC=1,3,5-benzenetricarboxylate, x=22-24), were synthesized through self-assembly, and their structures were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. These supramolecular microporous MOFs showed significant size and shape selectivity in the catalyzed oxidation of phenols, which is due to catalytic reactions taking place in the channels of the framework. Design strategy, synthesis, and self-assembly mechanism for the construction of these porous MOFs were discussed. - Grapical abstract: A modular design strategy has been developed to synthesize microporous metal-organic frameworks with potential catalytic activity by self-assembly of the framework-building blocks and the catalyst unit.

  8. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection

    NASA Astrophysics Data System (ADS)

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-01

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures.

  9. Composition-selective fabrication of ordered intermetallic Au-Cu nanowires and their application to nano-size electrochemical glucose detection.

    PubMed

    Kim, Si-In; Eom, Gayoung; Kang, Mijeong; Kang, Taejoon; Lee, Hyoban; Hwang, Ahreum; Yang, Haesik; Kim, Bongsoo

    2015-06-19

    Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures. PMID:26016531

  10. Hybrid catalyst containing nano-sized LaMnO{sub 3} and carbon black for high yield and selective ketonization of n-butanol

    SciTech Connect

    Cyganiuk, Aleksandra; Klimkiewicz, Roman; Lukaszewicz, Jerzy P.

    2011-03-15

    Graphical abstract: The performed investigations demonstrated a very high catalytic activity of the synthesized hybrid (LaMnO{sub 3}/carbon black) catalyst towards ketonization of n-butanol. Both selectivity (ca. 60%) and yield (ca. 40%) towards heptanone-4 seem to be very promising especially for conversion run at temperatures close to 480 {sup o}C. These parameters were achieved for the hybrid catalyst containing only 10 weight percents of LaMnO{sub 3}. Research highlights: {yields} A novel biotechnological way of a hybrid carbon-based catalyst fabrication {yields} Effective (high yield and selectivity) n-butanol conversion to heptanone-4. {yields} Nano-sized LaMnO{sub 3} crystallites uniformly distributed in carbon matrix. {yields} Exploitation of Salix viminalis tolerance to heavy metal ions. -- Abstract: An attempt has been made to synthesize a two-component hybrid material for highly selective catalytic ketonization of n-butanol. The perovskite-type oxide nano-crystallites were synthesized in the presence of carbon black particles by thermal transformation of equimolar mixture of lanthanum and manganese hydroxides into the perovskite-type oxide. The two-component material was tested as a catalyst for unconventional conversion of n-butanol to heptanone-4. The catalyst exhibited very high selectivity and yield towards the products, despite low content of LaMnO{sub 3} in the two-component material (less than 10% by weight). The low oxide content led to the reduction of the cost of catalyst fabrication and is compensated by its high dispersion (grains ca. 20-30 nm in diameter) providing high conversion and yield comparable to pure-oxide catalysts. Catalyst fabrication is simple and environment friendly since it does not require organic solvents and excess amount of heavy metals (La and Mn).

  11. Synthesis and application of nano-sized ionic imprinted polymer for the selective voltammetric determination of thallium.

    PubMed

    Nasiri-Majd, Mojtaba; Taher, Mohammad Ali; Fazelirad, Hamid

    2015-11-01

    A simple and selective thallium imprinted polymer was synthesized as a chemical modifier for the stripping voltammetric determination of Tl ions. The polymerization process (bulk polymerization) was performed with ethylene glycol dimethacrylate (crosslinking monomer) and methacrylic acid (functional monomer) in the presence of 2,2'-azobis(isobutyronitrile) (initiator). The electrochemical method was based on the accumulation of thallium ions at the surface of a modified carbon paste electrode with Tl imprinted polymer and multi-walled carbon nanotubes. After preconcentration process, the voltammetric measurements were carried out via electrolysis of the accumulated Tl ions in a closed circuit. Under the optimized conditions, a linear response range from 3.0 to 240 ng mL(-1) was obtained. The detection limit and RSD (100.0 ng mL(-1) of Tl) were calculated as 0.76 ng mL(-1) and ±2.7%, respectively. The suggested modified electrode has good characteristics such as excellent selectivity, high sensitivity and suitable stability. Also, it was successfully applied for the electrochemical determination of trace amounts of Tl in the environmental and biological samples. PMID:26452811

  12. Biomimetic mineralization of nano-sized, needle-like hydroxyapatite with ultrahigh capacity for lysozyme adsorption.

    PubMed

    Ma, Yi; Zhang, Juan; Guo, Shanshan; Shi, Jie; Du, Wenying; Wang, Zheng; Ye, Ling; Gu, Wei

    2016-11-01

    Because of its superior biocompatibility, hydroxyapatite (HA) has been widely exploited as a promising vehicle to deliver a broad range of therapeutics in a variety of biological systems. Herein, we report a biomimetic process to prepare nano-sized, colloidal stable HA with needle-like morphology by using carboxymethyl cellulose (CMC) as the template. It was revealed that the needle-like HA was transformed from the spherical amorphous calcium phosphate (ACP) nanoparticles after a 14-day period of aging under ambient conditions. The needle-like HA/CMC exhibited an ultra-high lysozyme adsorption capacity up to 930-940mg/g. Moreover, a sustained and pH-sensitive release of adsorbed lysozyme from HA/CMC was evidenced. Therefore, our biomimetic needle-like HA/CMC nanoparticles hold great potential in serving as an efficient carrier for the delivery and controlled release of lysozyme. PMID:27524053

  13. Colloidally stable selenium@copper selenide core@shell nanoparticles as selenium source for manufacturing of copper-indium-selenide solar cells.

    PubMed

    Dong, Hailong; Quintilla, Aina; Cemernjak, Marco; Popescu, Radian; Gerthsen, Dagmar; Ahlswede, Erik; Feldmann, Claus

    2014-02-01

    Selenium nanoparticles with diameters of 100-400nm are prepared via hydrazine-driven reduction of selenious acid. The as-prepared amorphous, red selenium (a-Se) particles were neither a stable phase nor were they colloidally stable. Due to phase transition to crystalline (trigonal), grey selenium (t-Se) at or even below room temperature, the particles merged rapidly and recrystallized as micronsized crystal needles. As a consequence, such Se particles were not suited for layer deposition and as a precursor to manufacture thin-film CIS (copper indium selenide/CuInSe2) solar cells. To overcome this restriction, Se@CuSe core@shell particles are presented here. For these Se@CuSe core@shell nanoparticles, the phase transition a-Se→t-Se is shifted to temperatures higher than 100°C. Moreover, a spherical shape of the particles is retained even after phase transition. Composition and structure of the Se@CuSe core@shell nanostructure are evidenced by electron microscopy (SEM/STEM), DLS, XRD, FT-IR and line-scan EDXS. As a conceptual study, the newly formed Se@CuSe core@shell nanostructures with CuSe acting as a protecting layer to increase the phase-transition temperature and to improve the colloidal stability were used as a selenium precursor for manufacturing of thin-film CIS solar cells and already lead to conversion efficiencies up to 3%. PMID:24267336

  14. Facile method for synthesis of nanosized β-MoO3 and their catalytic behavior for selective oxidation of methanol to formaldehyde

    NASA Astrophysics Data System (ADS)

    Thuy Phuong Pham, Thi; Hoang Duy Nguyen, Phuc; Vo, Tan Tai; Phuc Nguyen, Huu Huy; Loc Luu, Cam

    2015-12-01

    β-MoO3 was successfully synthesized from all commercial materials using a fast, effective and simple method and characterized by differential scanning calorimetry, x-ray powder diffraction, field emission scanning electron microscopy, infrared and Raman spectroscopy. The prepared sample was highly active and selective to formaldehyde formation from methanol over a wide range of reaction temperatures. β-MoO3 catalyst also exhibited stable methanol conversion and formaldehyde selectivity at around 84% and over 95% respectively for over 15 operating hours at 320 °C. However, it may be deactivated at elevated reaction temperature due to transformation of metastable to stable phase. It was revealed that the prepared catalyst maintains its high selectivity to formaldehyde during deactivation. This can be considered as an advantage of the prepared MoO3 catalyst in comparison with the industrial one.

  15. Polymer-inorganic coatings containing nanosized sorbents selective to radionuclides. 1. Latex/cobalt hexacyanoferrate(II) composites for cesium fixation.

    PubMed

    Bratskaya, Svetlana; Musyanovych, Anna; Zheleznov, Veniamin; Synytska, Alla; Marinin, Dmitry; Simon, Frank; Avramenko, Valentin

    2014-10-01

    Here we present a new approach to improve fixation of radionuclides on contaminated surfaces and eliminate their migration after nuclear accidents. The approach consists in fabrication of latex composite coatings, which combine properties of polymeric dust-suppressors preventing radionuclides migration with aerosols and selective inorganic sorbents blocking radionuclides leaching under contact with ground waters and atmospheric precipitates. Latex/cobalt hexacyanoferrate(II) (CoHCF) composites selective to cesium radionuclides were synthesized via "in situ" growth of CoHCF crystal on the surface of carboxylic or amino latexes using surface functional groups as ion-exchange centers for binding precursor ions Co(2+) and [Fe(CN)6](4-). Casting such composite dispersions with variable content of CoHCF on (137)Cs-contaminated sand has yielded protective coatings, which reduced cesium leaching to 0.4% compared to 70% leaching through original latex coatings. (137)Cs migration from the sand surface was efficiently minimized when the volume fraction of CoHCF in the composite film was as low as 0.46-1.7%. PMID:25203389

  16. Synthesis of nano-sized cyanide ion-imprinted polymer via non-covalent approach and its use for the fabrication of a CN(-)-selective carbon nanotube impregnated carbon paste electrode.

    PubMed

    Alizadeh, Taher; Sabzi, Reza Emamali; Alizadeh, Hassan

    2016-01-15

    Nano-sized CN(-)-imprinted polymer was synthesized by the copolymerization of methyl methacrylic acid (MAA), vinyl pyridine (VP) and ethylene glycol dimethacrylate in the presence of cyanide ion. The obtained polymeric nanoparticles were incorporated with carbon paste electrode (CPE) to produce a CN(-)-selective electrode. Functional monomer kind had crucial influence on the efficiency of the sensor. The presence of both VP and MAA in the structure of the imprinted polymer improved the sensing characteristics of the electrode. Also, the mole ratio of MAA/VP, cross-liker kind, cross-linker amount, solvent kind and amount were found to be effective factors in the electrode behavior. Presence of little amount of multi-walled carbon nanotubes (MWCNTs) in the CPE improved the detection range and response time of the electrode at the expense of small decrease in Nernstian slope. The electrode, containing CN(-)-imprinted polymer and MWCNTs showed a dynamic linear range of 1×10(-6)-1×10(-1)mol L(-1), Nernstian slope of 46.3±(0.6) mV and detection limit of 7.5×10(-7)mol L(-1); whereas, the same electrode in the absence of MWCNTs led to linear range, Nernstian slope and detection limit of 1×10(-5)-1×10(-1)molL(-1), 55.3±(0.7) mV and 8×10(-6)mol L(-1), respectively. The utility of the electrodes was checked by determination of cyanide ion in some real samples. PMID:26592581

  17. New use of metals as nanosized radioenhancers.

    PubMed

    Pottier, Agnès; Borghi, Elsa; Levy, Laurent

    2014-01-01

    Since the discovery of cisplatin about 40 years ago, the design of innovative metal-based anticancer drugs is a growing area of research. Transition metal coordination complexes offer potential advantages over the more common organic-based drugs, including a wide range of coordination number and geometries, accessible redox states, tunability of the thermodynamics and kinetics of ligand substitution, as well as a wide structural diversity. Metal-based substances interact with cell molecular targets, affecting biochemical functions resulting in cancer cell destruction. Radionuclides are another way to use metals as anticancer therapy. The metal nucleus of the unstable radionuclide becomes stable by emitting energy. The biological effect in different tissues is obtained by the absorption of this energy from the radiation emitted by the radionuclide, the principal target generally agreed for ionizing radiations being DNA. A new area of clinical research is now emerging using the same experimental metal elements, but in a radically different manner: metals and metal oxides used as crystalline nanosized particles. In this field, man-made functionalized nanoparticles of high electron density and well-defined size and shape offer the possibility of entering cancer cells and depositing high amounts of energy in the tumor only when exposed to ionizing radiations (on/off activity). These nanoparticles, such as hafnium oxide engineered as 50 nm-sized spheres, functionalized with a negative surface (NBTXR3 nanoparticles), have been developed as selective radioenhancers, which represents a breakthrough approach for the local treatment of solid tumors. The properties of NBTXR3 nanoparticles, their chemistry, size, shape and surface charge, have been designed for efficient tumor cell uptake. NBTXR3 brings a physical mode of action, that of radiotherapy, within the cancer cells themselves. Physicochemical characteristics of NBTXR3 have demonstrated a very promising benefit

  18. Synthesis and testing of nanosized zeolite Y

    NASA Astrophysics Data System (ADS)

    Karami, Davood

    This work focuses on the synthesis and testing of nanosized zeolite Y. The synthesis formulations of faujasite-type structure of zeolite Y prepared in nanosized form are described. The synthetic zeolite Y is the most widely employed for the preparation of fluid catalytic cracking (FCC) catalysts. The synthesis of zeolite Y is very complicated process. The mean particle size of zeolite Y is 1800 nm. The major challenge of this work involved reducing this average particle size to less than 500 nm. The preliminary experiments were conducted to obtain the pure zeolite Y using the soluble silicates as a silica source. This was achieved by applying the experimental design approach to study the effects of many parameters. The ageing time turned out to be the most significant variable affecting product purity. Based on the preliminary results, a detailed investigation was carried out to determine the effects of silica-alumina precursor preparations on zeolite Y synthesis. Aluminosilicate precursors were prepared by gelling and precipitation of soluble silicate. The as-prepared precursors were used for the hydrothermal synthesis of zeolite Y. The procedure of the precipitation of soluble silicate yielded pure zeolite Y at the conventional synthesis conditions. The extent of purity of zeolite Y depends on the surface areas of aluminosilicate precursors. A novel approach to zeolite Y synthesis was employed for the preparation of the pure nanosized zeolite Y. This was achieved by applying the method of impregnation of precipitated silica. This novel method of impregnation for zeolite Y preparation allows eliminating the vigorous agitation step required for the preparation of a homogeneous silica solution, thereby simplifying the synthesis of zeolite Y in one single vessel. In case of the synthesis of nanosized zeolite Y, the effect of varying the organic templates on the formation of nanosized particles of zeolite Y was investigated, while all other reaction parameters were

  19. Nanosized Ultrasound Enhanced-Contrast Agent for in Vivo Tumor Imaging via Intravenous Injection.

    PubMed

    Kim, Manse; Lee, Jong Hyun; Kim, Se Eun; Kang, Seong Soo; Tae, Giyoong

    2016-04-01

    To enhance the detection limit of ultrasound (US) imaging, ultrasound enhanced-contrast agents (UECAs) that can go preferentially to the target tissue such as a tumor and amplify the US signal have been developed. However, nanosized UECAs among various UECAs developed are very limited to clearly demonstrate proper ability for selective tumor detection by US imaging upon their intravenous injection. In this study, we prepared CaCO3 nanoparticles that were formed inside a flexible and biocompatible pluronic-based nanocarrier. This nanosized UECA was stable in serum-containing media and generated CO2, more preferentially at low pH; thus, it could be detected by US imaging. After intravenous injection into tumor-bearing mice, this nanosized UECA showed a significant US contrast enhancement at the tumor site in 1 h, in contrast to no change in the liver, followed by a rapid clearance from the body in 24 h. Therefore, the present nanosized UECA could be applied as an effective diagnostic modality for in vivo tumor imaging by ultrasonography. PMID:27010717

  20. Studies of photoredox reactions on nanosize semiconductors

    SciTech Connect

    Wilcoxon, J.P.; Parsapour, F.; Kelly, D.F.

    1997-02-01

    Light induced electron transfer (ET) from nanosize semiconductors Of MoS{sub 2} to organic electron acceptors such as 2,2`-bipyridine (bpy) and methyl substituted 4,4`,5,5`-tetramethyl- 2,2`-bipyridine (tmb) was studied by static and time resolved photoluminescence spectroscopy. The kinetics of ET were varied by changing the nanocluster size (the band gap), the electron acceptor, and the polarity of the solvent. MoS{sub 2} is an especially interesting semiconductor material as it is an indirect semiconductor in bulk form, and has a layered covalent bonding arrangement which is highly resistant to photocorrosion.

  1. Nanosizing of drugs: Effect on dissolution rate

    PubMed Central

    Dizaj, S. Maleki; Vazifehasl, Zh.; Salatin, S.; Adibkia, Kh.; Javadzadeh, Y.

    2015-01-01

    The solubility, bioavailability and dissolution rate of drugs are important parameters for achieving in vivo efficiency. The bioavailability of orally administered drugs depends on their ability to be absorbed via gastrointestinal tract. For drugs belonging to Class II of pharmaceutical classification, the absorption process is limited by drug dissolution rate in gastrointestinal media. Therefore, enhancement of the dissolution rate of these drugs will present improved bioavailability. So far several techniques such as physical and chemical modifications, changing in crystal habits, solid dispersion, complexation, solubilization and liquisolid method have been used to enhance the dissolution rate of poorly water soluble drugs. It seems that improvement of the solubility properties ofpoorly water soluble drugscan translate to an increase in their bioavailability. Nowadays nanotechnology offers various approaches in the area of dissolution enhancement of low aqueous soluble drugs. Nanosizing of drugs in the form of nanoparticles, nanocrystals or nanosuspensions not requiring expensive facilities and equipment or complicated processes may be applied as simple methods to increase the dissolution rate of poorly water soluble drugs. In this article, we attempted to review the effects of nanosizing on improving the dissolution rate of poorly aqueous soluble drugs. According to the reviewed literature, by reduction of drug particle size into nanometer size the total effective surface area is increased and thereby dissolution rate would be enhanced. Additionally, reduction of particle size leads to reduction of the diffusion layer thickness surrounding the drug particles resulting in the increment of the concentration gradient. Each of these process leads to improved bioavailability. PMID:26487886

  2. Effects of nanosized constriction on thermal transport properties of graphene

    PubMed Central

    2014-01-01

    Thermal transport properties of graphene with nanosized constrictions are investigated using nonequilibrium molecular dynamics simulations. The results show that the nanosized constrictions have a significant influence on the thermal transport properties of graphene. The thermal resistance of the nanosized constrictions is on the order of 107 to 109 K/W at 150 K, which reduces the thermal conductivity by 7.7% to 90.4%. It is also found that the constriction resistance is inversely proportional to the width of the constriction and independent of the heat current. Moreover, we developed an analytical model for the ballistic thermal resistance of the nanosized constrictions in two-dimensional nanosystems. The theoretical prediction agrees well with the simulation results in this paper, which suggests that the thermal transport across the nanosized constrictions in two-dimensional nanosystems is ballistic in nature. PACS 65.80.CK; 61.48.Gh; 63.20.kp; 31.15.xv PMID:25232292

  3. Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats

    PubMed Central

    Matsuzaki, Takashi; Araki, Ryo; Tsuchida, Shota; Thanikachalam, Punniyakoti V.; Fukuta, Tatsuya; Asai, Tomohiro; Yamato, Masaki; Sanada, Shoji; Asanuma, Hiroshi; Asano, Yoshihiro; Asakura, Masanori; Hanawa, Haruo; Hao, Hiroyuki; Oku, Naoto; Takashima, Seiji; Kitakaze, Masafumi; Sakata, Yasushi; Minamino, Tetsuo

    2016-01-01

    Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug’s effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents. PMID:27501378

  4. Photo-triggered release in polyamide nanosized capsules

    SciTech Connect

    Marturano, V.; Ambrogi, V.; Cerruti, P.; Giamberini, M.; Tylkowski, B.

    2014-05-15

    In this work, nanosized capsules based on a lightly cross-linked polyamide containing azobenzene moieties in the main chain were synthesized by miniemulsion interfacial polymerization. The obtained nanocapsules were loaded either with toluene or with the fluorescent probe coumarin-6 as a core. Diameters of the nanocapsules were in the 100-900 nm range, depending on the selected emulsion conditions. The morphology and shape of the samples were observed by TEM and SEM while the emulsion droplets and nanocapsules size was measured by DLS. Under continuous UV irradiation the polymer underwent E-Z photoisomerization allowing the release of the encapsulated material. Variation in diameter of the nanocapsules with the time of UV irradiation was detected through DLS analysis. 10-30% growth was observed, depending on the sample. The kinetics of release of coumarin-6 was followed by spectrofluorimetry in ethanol. In absence of irradiation, the fluorescence intensity appeared to be constant over time, while it increased when the sample was irradiated with 360 nm UV light.

  5. Photo-triggered release in polyamide nanosized capsules

    NASA Astrophysics Data System (ADS)

    Marturano, V.; Ambrogi, V.; Cerruti, P.; Giamberini, M.; Tylkowski, B.

    2014-05-01

    In this work, nanosized capsules based on a lightly cross-linked polyamide containing azobenzene moieties in the main chain were synthesized by miniemulsion interfacial polymerization. The obtained nanocapsules were loaded either with toluene or with the fluorescent probe coumarin-6 as a core. Diameters of the nanocapsules were in the 100-900 nm range, depending on the selected emulsion conditions. The morphology and shape of the samples were observed by TEM and SEM while the emulsion droplets and nanocapsules size was measured by DLS. Under continuous UV irradiation the polymer underwent E-Z photoisomerization allowing the release of the encapsulated material. Variation in diameter of the nanocapsules with the time of UV irradiation was detected through DLS analysis. 10-30% growth was observed, depending on the sample. The kinetics of release of coumarin-6 was followed by spectrofluorimetry in ethanol. In absence of irradiation, the fluorescence intensity appeared to be constant over time, while it increased when the sample was irradiated with 360 nm UV light.

  6. Protein interactions with nanosized hydrotalcites of different composition.

    PubMed

    Bellezza, Francesca; Alberani, Alistella; Posati, Tamara; Tarpani, Luigi; Latterini, Loredana; Cipiciani, Antonio

    2012-01-01

    Nanosized hydrotalcite-like compounds (HTlc) with different chemical composition were prepared and used to study protein adsorption. Two soft proteins, myoglobin (Mb) and bovine serum albumin (BSA), were chosen to investigate the nature of the forces controlling the adsorption and how these depend on the chemical composition of the support. Both proteins strongly interact with HTlc exhibiting in most cases a Langmuir-type adsorption. Mb showed a higher affinity for Nickel Chromium (NiCr-HTlc) than for Nickel Aluminum (NiAl-HTlc), while for BSA no significant differences between supports were found. Adsorption experiments in the presence of additives showed that proteins exhibited different types of interactions onto the same HTlc surface and that the adsorption was strongly suppressed by the addition of disodium hydrogen phosphate (Na(2)HPO(4)). Atomic force microscopy images showed that the adsorption of both proteins onto nanoparticles was followed by the aggregation of biocomposites, with a more disordered structure for BSA. Fluorescence measurements for adsorbed Mb showed that the inorganic nanoparticles induced conformational changes in the biomolecules; in particular, the interactions with HTlc surface quenched the tryptophan fluorescence and this process was particularly efficient for NiCr-HTlc. The adsorption of BSA onto the HTlc nanoparticles induced a selective quenching of the exposed fluorescent residues, as indicated by the blue-shift of the emission spectra of tryptophan residues and by the shortening of the fluorescence decay times. PMID:22115829

  7. Preferential spin canting in nanosize zinc ferrite

    NASA Astrophysics Data System (ADS)

    Pandey, Brajesh; Litterst, F. J.; Baggio-Saitovitch, E. M.

    2015-07-01

    Zinc ferrite nanoparticles powder with average size of 10.0±0.5 nm was synthesized by the citrate precursor route. We studied the structural and magnetic properties using X-ray diffraction, vibrating sample magnetometry and Mössbauer spectroscopy. X-ray diffraction patterns show that the synthesized zinc ferrite possesses good spinel structure. Both Mössbauer and magnetization data indicate superparamagnetic ferrimagnetic particles at room temperature. The magnetic behavior is determined by a considerable degree of cation inversion with FeIII in tetrahedral A-sites. Mössbauer spectroscopy at low temperature and in high applied magnetic field reveals that A-site spins are aligned antiparallel to the applied field with some possible angular scatter whereas practically all octahedral B-site spins are canted contrasting some earlier reported partial B-site spin canting in nanosize zinc ferrite. Deviations from the antiferromagnetic arrangement of B-site spins are supposed to be caused by magnetic frustration effects.

  8. Studies of photoredox reactions on nanosize semiconductors

    SciTech Connect

    Wilcoxon, J.P.; Parsapour, F.; Kelley, D.F.

    1997-08-01

    Light induced electron transfer (ET) from nanosize semiconductors of MoS{sub 2} to organic electron acceptors such as 2,2{prime}-bipyridine (bpy) and methyl substituted 4,4{prime},5,5{prime}-tetramethyl-2,2{prime}-bipyridine (tmb) was studied by static and time resolved photoluminescence spectroscopy. The kinetics of ET were varied by changing the nanocluster size (the band gap), the electron acceptor, and the polarity of the solvent. MoS{sub 2} is an especially interesting semiconductor material as it is an indirect semiconductor in bulk form, and has a layered covalent bonding arrangement which is highly resistant to photocorrosion. Et occurs following photoexcitation of the direct band gap. Quantum confinement results in the smaller nanoclusters having higher conduction band energies, and therefore larger ET driving forces. The ET reaction energies may be varied by changing the electron acceptor, by varying the size of the MoS{sub 2} nanocluster or by varying the polarity of the solvent. In addition, varying the polarity of the solvent affects the reorganization energy and the barrier to electron transfer. TMB is harder to reduce, and thus has a smaller ET driving force than bpy. The solvent polarity is varied by varying the composition of acetonitrile/benzene mixed solvents.

  9. Template-free nanosized faujasite-type zeolites

    NASA Astrophysics Data System (ADS)

    Awala, Hussein; Gilson, Jean-Pierre; Retoux, Richard; Boullay, Philippe; Goupil, Jean-Michel; Valtchev, Valentin; Mintova, Svetlana

    2015-04-01

    Nanosized faujasite (FAU) crystals have great potential as catalysts or adsorbents to more efficiently process present and forthcoming synthetic and renewable feedstocks in oil refining, petrochemistry and fine chemistry. Here, we report the rational design of template-free nanosized FAU zeolites with exceptional properties, including extremely small crystallites (10-15 nm) with a narrow particle size distribution, high crystalline yields (above 80%), micropore volumes (0.30 cm3 g-1) comparable to their conventional counterparts (micrometre-sized crystals), Si/Al ratios adjustable between 1.1 and 2.1 (zeolites X or Y) and excellent thermal stability leading to superior catalytic performance in the dealkylation of a bulky molecule, 1,3,5-triisopropylbenzene, probing sites mostly located on the external surface of the nanosized crystals. Another important feature is their excellent colloidal stability, which facilitates a uniform dispersion on supports for applications in catalysis, sorption and thin-to-thick coatings.

  10. Synthesis and characterization of nanosized lead oxide

    NASA Astrophysics Data System (ADS)

    Laak, Sheau Tyan

    Nanosized lead oxide as well as copper-doped lead oxide are prepared using two different synthetic techniques; hydrothermal and precipitation. The precipitation method involves simply reacting lead (IV) acetate with distilled water. On the other hand, the hydrothermal process used an autoclave with the presence of Polyvinyl Pyrrolidone (PVP) to prepare lead oxide (PbO 2) hollow spheres, and lead oxide (Pb3O4) microtubes at reaction temperatures of 90°C and 180°C, respectively. Characterization of the synthesized material was carried out using X-Ray Diffraction (XRD), Thermal Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), and Scanning Electron Microscopy (SEM). X-Ray Diffraction shows that the prepared lead oxides using the hydrothermal process with a reaction a temperature of 90°C is crystalline α PbO 2. SEM shows that the prepared particles are hollow spheres. It also shows uniformity in shape and size. In contrast, X-Ray Diffraction and SEM show that the prepared lead oxide using the hydrothermal process with a reaction temperature of 180°C is nanofiber crystalline α PbO2. It also shows uniformity in shape and size. As to the precipitation method, X-Ray Diffraction shows that the sample is crystalline β PbO2. X-Ray Diffraction revealed that these lead oxides show two different transitions, from β PbO2 to Pb3O4, and Pb3O4 to PbO. These observations were supported by TGA and DTA at 400°C and 700°C, respectively. SEM analysis shows that the prepared β PbO2 sample does not show uniformity, neither in size nor in shape. Indeed, particles appear to congregate and form much larger particles. The results from our study suggest that simple precipitation can lead to the product of PbO2, it however cannot guarantee uniformity. The use of an autoclave in the presence of a polymer such as PVP allowed the precipitation of uniform nano PbO2. In addition, the temperature appeared to affect the morphology of the final product. When low temperature is

  11. Processing of silicon nitride and alumina nanosize powders

    SciTech Connect

    Gonzalez, E.J.; Piermarini, G.; Hockey, B.; Malghan, S.G.

    1995-08-01

    The effects of pressure on the compaction and subsequent processing of nanosize {gamma} alumina powders were studied. A 3 mm diameter piston/cylinder die was used to compact the nanosize powders to pressures of 1 and 2.5 GPa. The green bodies were sintered at temperatures up to 1600{degrees}C. Results show that green body density can be increased by higher compaction pressures. It appears that as a result of the {gamma}-to-{alpha} transformation in alumina, higher green density does not necessarily produce a higher density sintered alumina body. The microstructures of the sintered bodies are described in terms of porosity and phase content.

  12. Functionally charged nanosize particles differentially activate BV2 microglia.

    EPA Science Inventory

    The effect of particle surface charge on the biological activation of immortalized mouse microglia (BV2) was examined. Nanosize (860-950 nm) spherical polystyrene microparticles (SPM) were coated with carboxyl (COOH-) or dimethyl amino (CH3)2-N- groups to give a net negative or p...

  13. Low temperature fabrication from nano-size ceramic powders

    SciTech Connect

    Gonzalez, E.J.; Piermarini, G.J.; Hockey, B.

    1995-06-01

    The objective of the compaction process is to produce a dense green-state compact from a nanosize powder that subsequently can be sintered at high temperatures to form a dense ceramic piece. High density in the green-state after pressing is of primary importance for achieving high densities after sintering. Investigation of the compaction behavior of ceramic powders, therefore, is an important part of characterization of raw ceramic powders and evaluation of their compaction behavior, analysis of interaction between particles, and the study of microstructure of green body (unsintered) during pressure-forming processes. The compaction of nanosize ceramic particles into high density green bodies is very difficult. For the nanosize materials used in this study (amorphous Si{sub 3}N{sub 4} and {gamma} Al{sub 2}O{sub 3}), there is no evidence by TEM of partial sintering after synthesis. Nevertheless, strong aggregation forces, such as the van der Waals surface forces of attraction, exist and result in moderate precursor particle agglomeration. More importantly, these attractive surface forces, which increase in magnitude with decreasing particle size, inhibit interparticle sliding necessary for particle rearrangement to denser bodies during subsequent compaction. Attempts to produce high density green body compacts of nanosize particles, therefore, generally have been focused on overcoming these surface forces of attraction by using either dispersive fluids or high pressures with or without lubricating liquids. In the present work, the use of high pressure has been employed as a means of compacting nanosize powders to relatively high green densities.

  14. Nano-sized, quaternary titanium(IV) metal-organic frameworks with multidentate ligands

    NASA Astrophysics Data System (ADS)

    Baranwal, Balram Prasad; Singh, Alok Kumar

    2010-12-01

    Some mononuclear nano-sized, quaternary titanium(IV) complexes having the general formula [Ti(acac)(OOCR) 2(SB)] (where Hacac = acetylacetone, R = C 15H 31 or C 17H 35, HSB = Schiff bases) have been synthesized using different multidentate ligands. These were characterized by elemental analyses, molecular weight determinations and spectral (FTIR, 1H NMR and powder XRD) studies. Conductance measurement indicated their non-conducting nature which may behave like insulators. Structural parameters like the values of limiting indices h, k, l, cell constants a, b, c, angles α, β, γ and particle size are calculated from powder XRD data for complex 1 which indicated nano-sized triclinic system in them. Bidentate chelating nature of acetylacetone, carboxylate and Schiff base anions in the complexes was established by their infrared spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. On the basis of physico-chemical studies, coordination number 8 was assigned for titanium(IV) in the complexes. Transmission electron microscopy (TEM) and the selected area electron diffraction (SAED) studies indicated spherical particles with poor crystallinity.

  15. Nanosized hydroxyapatite powder synthesized from eggshell and phosphoric acid.

    PubMed

    Lee, Sang-Jin; Yoon, Young-Soo; Lee, Myung-Hyun; Oh, Nam-Sik

    2007-11-01

    The present research describes synthesis of highly sinterable, nano-sized hydroxyapatite (HAp) powders using a wet chemical route with recycled eggshell and phosphoric acid as calcium and phosphorous sources. The raw eggshell was easily turned to CaO by the calcining process, and phosphoric acid was mixed with the calcined eggshell by the wet, ball-milling method. The crystalline development and microstructures of the synthesized powders and sintered samples were examined by X-ray diffractometry and scanning electron microscopy, respectively. The observed phases on the powder synthesis process were dependent on the mixing ratio (wt%) of the calcined eggshell to phosphoric acid and the heating temperature. The ball-milled, nano-sized HAp powder, which has an average particle size of 70 nm, was fully densified at 1300 degrees C for 1h. The Ca/P ratio for stoichiometric composition of HAp was controlled by adjustment of the mixing ratio. PMID:18047119

  16. Synthesis of nanosize BPO{sub 4} under microwave irradiation

    SciTech Connect

    Wang, Rui; Jiang, Heng; Gong, Hong; Zhang, Jun

    2012-08-15

    Highlights: ► Nanosize BPO{sub 4} are prepared under microwave-irradiation conditions. ► This reaction is only performed at less than 640 W power for 2.5–5 min. ► The particles of sample irradiated at 400 W are 40–90 nm in size and well dispersed. ► A simple, fast and green procedure for synthesis of nanosize BPO{sub 4} is developed. -- Abstract: Nanosize BPO{sub 4} was synthesized using H{sub 3}BO{sub 3} and H{sub 3}PO{sub 4} (85%) as raw materials under microwave irradiation. This reaction was performed at powers lower than 640 W and irradiation time ranging from 2.5 min to 5 min, which were only a fraction of the time required for conventional synthetic procedures. The structure of the as-prepared BPO{sub 4} is analogous to that of a high cristobalite. The particle sizes of the samples irradiated at 640 and 400 W range from 40 nm to 90 nm and 30 nm to 60 nm, respectively. The effects of different conditions on the experimental outcome are also discussed.

  17. Nanosized Selenium: A Novel Platform Technology to Prevent Bacterial Infections

    NASA Astrophysics Data System (ADS)

    Wang, Qi

    As an important category of bacterial infections, healthcare-associated infections (HAIs) are considered an increasing threat to the safety and health of patients worldwide. HAIs lead to extended hospital stays, contribute to increased medical costs, and are a significant cause of morbidity and mortality. In the United States, infections encountered in the hospital or a health care facility affect more than 1.7 million patients, cost 35.7 billion to 45 billion, and contribute to 88,000 deaths in hospitals annually. The most conventional and widely accepted method to fight against bacterial infections is using antibiotics. However, because of the widespread and sometimes inappropriate use of antibiotics, many strains of bacteria have rapidly developed antibiotic resistance. Those new, stronger bacteria pose serious, worldwide threats to public health and welfare. In 2014, the World Health Organization (WHO) reported antibiotic resistance as a global serious threat that is no longer a prediction for the future but is now reality. It has the potential to affect anyone, of any age, in any country. The most effective strategy to prevent antibiotic resistance is minimizing the use of antibiotics. In recent years, nanomaterials have been investigated as one of the potential substitutes of antibiotics. As a result of their vastly increased ratio of surface area to volume, nanomaterials will likely exert a stronger interaction with bacteria which may affect bacterial growth and propagation. A major concern of most existing antibacterial nanomaterials, like silver nanoparticles, is their potential toxicity. But selenium is a non-metallic material and a required nutrition for the human body, which is recommended by the FDA at a 53 to 60 μg daily intake. Nanosized selenium is considered to be healthier and less toxic compared with many metal-based nanomaterials due to the generation of reactive oxygen species from metals, especially heavy metals. Therefore, the objectives of

  18. Tailoring properties of porous Poly (vinylidene fluoride) scaffold through nano-sized 58s bioactive glass.

    PubMed

    Shuai, Cijun; Huang, Wei; Feng, Pei; Gao, Chengde; Shuai, Xiong; Xiao, Tao; Deng, Youwen; Peng, Shuping; Wu, Ping

    2016-01-01

    The biological properties of porous poly (vinylidene fluoride) (PVDF) scaffolds fabricated by selective laser sintering were tailored through nano-sized 58s bioactive glass. The results showed that 58s bioactive glass distributed evenly in the PVDF matrix. There were some exposed particles on the surface which provided attachment sites for biological response. It was confirmed that the scaffolds had highly bioactivity by the formation of bone-like apatite in simulated body fluid. And the bone-like apatite became dense with the increase in 58s bioactive glass and culture time. Moreover, the scaffolds were suitable for cell adhesion and proliferation compared with the PVDF scaffolds without 58s bioactive glass. The research showed that the PVDF/58s bioactive glass scaffolds had latent application in bone tissue engineering. PMID:26592544

  19. Mr Fluids with Nano-Sized Magnetic Particles

    NASA Astrophysics Data System (ADS)

    Kormann, Cl.; Laun, H. M.; Richter, H. J.

    Recently magnetorheological fluids with nanosized magnetic ferrite particles have become available. Their composition, rheological and magnetic properties are described. A comparison with conventional MR fluids based on micron-sized particles is given. The yield stress of nano-MR fluids can be increased by a moderate magnetic field (0,2 T) by 4000 Pa. It can be modulated by the magnetic field with a response time of less than 5 ms. Details are given on the long term thermal stability at 150 °C, on flow properties at elevated temperatures and at high shear rates. Design principles for MR fluid actuator design are outlined.

  20. Electrical and magnetic properties of nano-sized magnesium ferrite

    NASA Astrophysics Data System (ADS)

    T, Smitha; X, Sheena; J, Binu P.; Mohammed, E. M.

    2015-02-01

    Nano-sized magnesium ferrite was synthesized using sol-gel techniques. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. Vibration Sample Magnetometer was used to record the magnetic measurements. XRD analysis reveals the prepared sample is single phasic without any impurity. Particle size calculation shows the average crystallite size of the sample is 19nm. FTIR analysis confirmed spinel structure of the prepared samples. Magnetic measurement study shows that the sample is ferromagnetic with high degree of isotropy. Hysterisis loop was traced at temperatures 100K and 300K. DC electrical resistivity measurements show semiconducting nature of the sample.

  1. Ductility and work hardening in nano-sized metallic glasses

    SciTech Connect

    Chen, D. Z.; Gu, X. W.; An, Q.; Goddard, W. A.; Greer, J. R.

    2015-02-09

    In-situ nano-tensile experiments on 70 nm-diameter free-standing electroplated NiP metallic glass nanostructures reveal tensile true strains of ∼18%, an amount comparable to compositionally identical 100 nm-diameter focused ion beam samples and ∼3 times greater than 100 nm-diameter electroplated samples. Simultaneous in-situ observations and stress-strain data during post-elastic deformation reveal necking and work hardening, features uncharacteristic for metallic glasses. The evolution of free volume within molecular dynamics-simulated samples suggests a free surface-mediated relaxation mechanism in nano-sized metallic glasses.

  2. Direct conversion of bio-ethanol to isobutene on nanosized Zn(x)Zr(y)O(z) mixed oxides with balanced acid-base sites.

    PubMed

    Sun, Junming; Zhu, Kake; Gao, Feng; Wang, Chongmin; Liu, Jun; Peden, Charles H F; Wang, Yong

    2011-07-27

    We report the design and synthesis of nanosized Zn(x)Zr(y)O(z) mixed oxides for direct and high-yield conversion of bio-ethanol to isobutene (~83%). ZnO is addded to ZrO(2) to selectively passivate zirconia's strong Lewis acidic sites and weaken Brönsted acidic sites, while simultaneously introducing basicity. As a result, the undesired reactions of bio-ethanol dehydration and acetone polymerization/coking are suppressed. Instead, a surface basic site-catalyzed ethanol dehydrogenation to acetaldehyde, acetaldehyde to acetone conversion via a complex pathway including aldol-condensation/dehydrogenation, and a Brönsted acidic site-catalyzed acetone-to-isobutene reaction pathway dominates on the nanosized Zn(x)Zr(y)O(z) mixed oxide catalyst, leading to a highly selective process for direct conversion of bio-ethanol to isobutene. PMID:21682296

  3. Nanosizing and nanoconfinement: new strategies towards meeting hydrogen storage goals.

    PubMed

    de Jongh, Petra E; Adelhelm, Philipp

    2010-12-17

    Hydrogen is expected to play an important role as an energy carrier in a future, more sustainable society. However, its compact, efficient, and safe storage is an unresolved issue. One of the main options is solid-state storage in hydrides. Unfortunately, no binary metal hydride satisfies all requirements regarding storage density and hydrogen release and uptake. Increasingly complex hydride systems are investigated, but high thermodynamic stabilities as well as slow kinetics and poor reversibility are important barriers for practical application. Nanostructuring by ball-milling is an established method to reduce crystallite sizes and increase reaction rates. Since five years attention has also turned to alternative preparation techniques that enable particle sizes below 10 nanometers and are often used in conjunction with porous supports or scaffolds. In this Review we discuss the large impact of nanosizing and -confinement on the hydrogen sorption properties of metal hydrides. We illustrate possible preparation strategies, provide insight into the reasons for changes in kinetics, reversibility and thermodynamics, and highlight important progress in this field. All in all we provide the reader with a clear view of how nanosizing and -confinement can beneficially affect the hydrogen sorption properties of the most prominent materials that are currently considered for solid-state hydrogen storage. PMID:21080405

  4. Micro- and Nanosized Particles in Nasal Mucosa: A Pilot Study

    PubMed Central

    2015-01-01

    Objective. The aim of this prospective study is to evaluate presence and quantity of micro- and nanosized particles (NPs) and interindividual differences in their distribution and composition in nasal mucosa. Methods. Six samples of nasal mucosa obtained by mucotomy from patients with chronic hypertrophic rhinosinusitis were examined. Samples divided into 4 parts according to the distance from the nostrils were analyzed by scanning electron microscopy and Raman microspectroscopy to detect solid particles and characterize their morphology and composition. A novel method of quantification of the particles was designed and used to evaluate interindividual differences in distribution of the particles. The findings were compared with patients' employment history. Results. In all the samples, NPs of different elemental composition were found (iron, barium, copper, titanium, etc.), predominantly in the parts most distant from nostrils, in various depths from the surface of the mucosa and interindividual differences in their quantity and composition were found, possibly in relation to professional exposition. Conclusions. This study has proven the possibility of quantification of distribution of micro- and nanosized particles in tissue samples and that the NPs may deposit in deeper layers of mucosa and their elemental composition may be related to professional exposition to the sources of NPs. PMID:26125023

  5. Antigenic composition of single nano-sized extracellular blood vesicles.

    PubMed

    Arakelyan, Anush; Ivanova, Oxana; Vasilieva, Elena; Grivel, Jean-Charles; Margolis, Leonid

    2015-04-01

    Extracellular vesicles (EVs) are important in normal physiology and are altered in various pathologies. EVs produced by different cells are antigenically different. Since the majority of EVs are too small for routine flow cytometry, EV composition is studied predominantly in bulk, thus not addressing their antigenic heterogeneity. Here, we describe a nanoparticle-based technique for analyzing antigens on single nano-sized EVs. The technique consists of immuno-capturing of EVs with 15-nm magnetic nanoparticles, staining captured EVs with antibodies against their antigens, and separating them from unbound EVs and free antibodies in a magnetic field, followed by flow analysis. This technique allows us to characterize EVs populations according to their antigenic distribution, including minor EV fractions. We demonstrated that the individual blood EVs carry different sets of antigens, none being ubiquitous, and quantified their distribution. The physiological significance of antigenically different EVs and their correlation with different pathologies can now be directly addressed. From the clinical editor: This study reports a nanoparticle-based technique for analyzing antigens on single nano-sized extracellular vehicles (EV). The technique consists of immuno-capturing of EVs with 15-nm magnetic nanoparticles, followed by staining the captured EVs with antibodies and separating them via a magnetic field, followed by flow analysis. This technique enables studies of antigenic properties of individual EVs that conventionally can only be studied in bulk. PMID:25481806

  6. Adsorption of bovine serum albumin on nanosized magnetic particles.

    PubMed

    Peng, Z G; Hidajat, K; Uddin, M S

    2004-03-15

    Adsorption of bovine serum albumin (BSA) on nanosized magnetic particles (Fe(3)O(4)) was carried out in the presence of carbodiimide. The equilibrium and kinetics of the adsorption process were studied. Nanosized magnetic particles (Fe(3)O(4)) were prepared by the chemical precipitation method using Fe2+, Fe3+ salts, and ammonium hydroxide under a nitrogen atmosphere. Characterizations of magnetic particles were carried out using transmission electron microscopy (TEM) and a vibrating sample magnetometer (VSM). Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to confirm the attachment of BSA on magnetic particles. Effects of pH and salt concentrations were investigated on the adsorption process. The experimental results show that the adsorption of BSA on magnetic particles was affected greatly by the pH, while the effect of salt concentrations was insignificant at a low concentration range. The adsorption equilibrium isotherm was fitted well by the Langmuir model. The maximum adsorption of BSA on magnetic particles occurred at the isoelectric point of BSA. Adsorption kinetics was analyzed by a linear driving force mass-transfer model. BSA was desorbed from magnetic particles under alkaline conditions, which was confirmed by SDS-PAGE electrophoresis and FTIR results. PMID:14972603

  7. Hydrophobic polymers in nano-sized water droplets

    NASA Astrophysics Data System (ADS)

    Tilakaratne, Buddhi; Masood, Samina; Cheung, Margaret

    2008-03-01

    As simulations of biopolymers take place in confined and tight spaces, such as protein folding in the interior of bacteria chaperones or the exit tunnels of ribosomes, quantitative analyses of the confinement effects on both biopolymers and solvent molecules become the center of attention as the solvent-mediated interactions are too profound to solve analytically. We are in the progress to investigate the solvation of hexane molecules in various nano-sized water droplets. Free energy profiles for a single hexane molecule in droplets show that the droplet surfaces are favored. Averaged configurations of hexane molecules at the interior and the surface are computed using the umbrella sampling methods. The implications of our results for protein stability in confined spaces will be discussed.

  8. Toxicological Concerns of Engineered Nanosize Drug Delivery Systems.

    PubMed

    Mukherjee, Biswajit; Maji, Ruma; Roychowdhury, Samrat; Ghosh, Saikat

    2016-01-01

    Matters when converted into nanosize provide some unique surface properties, which are different from those of the bulk materials. Nanomaterials show some extraordinary behavioral patterns because of those properties, such as supermagnetism, quantum confinement, etc. A great deal of implication of nanomaterials in nanomedicine has already been realized. Utility of nanomaterials as drug nanocarrier projects many potential advantages of them in drug delivery. Despite many such advantages, the potential risk of health and environmental hazards related to them cannot be ignored. Here various physicochemical factors, such as chemical nature, degradability, surface properties, surface charge, particle size, and shape, have been shown to play a crucial role in toxicity related to drug nanocarriers. Evidence-based findings of some drug nanocarriers have been incorporated to provide distinct knowledge to the readers in the field. A glimpse of current regulatory controls and measures required to combat the challenges of toxicological aspects of drug nanocarriers have been described. PMID:24100254

  9. Kinetic regularities of thermal transformations in nanosized lead films

    NASA Astrophysics Data System (ADS)

    Surovoi, E. P.; Bin, S. V.; Bugerko, L. N.; Surovaya, V. E.

    2015-01-01

    The transformations in nanosized lead films were studied by optical spectroscopy, microscopy, and gravimetry at different film thicknesses ( d = 2-115 nm) and thermal treatment temperatures ( T = 373-573 K). The kinetic curves of conversion were adequately described in terms of the linear, inverse logarithmic, parabolic, and logarithmic laws. The contact potential difference was measured for Pb and PbO films and photo-EMF was measured for Pb-PbO systems. The energy band diagram was constructed for Pb-PbO systems. A model of the thermal transformation of Pb films was suggested, which included the stages of oxygen adsorption, charge carrier distribution in the contact field of Pb-PbO, and formation of lead(II) oxide.

  10. Nanosized copper ferrite materials: Mechanochemical synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Manova, Elina; Tsoncheva, Tanya; Paneva, Daniela; Popova, Margarita; Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan

    2011-05-01

    Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Mössbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe 2O 3. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium.

  11. Sonochemical preparation of nanosized amorphous Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Shafi, K. V. P. M.; Gedanken, A.; Goldfarb, R. B.; Felner, I.

    1997-05-01

    Nanosized amorphous alloy powders of Fe20Ni80, Fe40Ni60, and Fe60Ni40 were prepared by sonochemical decomposition of solutions of volatile organic precursors, Fe(CO)5 and Ni(CO)4 in decalin, under an argon pressure of 100 to 150 kPa at 273 K. Magnetic susceptibility of Fe40Ni60 and Fe60Ni40 indicates blocking temperatures of 35 K and a magnetic particle size of about 6 nm. Thermogravimetric measurements of Fe20Ni80 give Curie temperatures of 322 °C for amorphous and 550 °C for crystallized forms. Differential scanning calorimetry exhibits an endothermic transition at 335 °C from a combination of the magnetic phase transition and alloy crystallization. The Mössbauer spectrum of crystallized Fe20Ni80 shows a sextet pattern with a hyperfine field of 25.04 T.

  12. Metastable nanosized aluminum powder as a reactant in energetic formulations

    SciTech Connect

    Katz, J.; Tepper, F.; Ivanov, G.V.; Lerner, M.I.; Davidovich, V.

    1998-12-01

    Aluminum powder is an important ingredient in many propellant, explosives and pyrotechnic applications. The production of nanosized aluminum powder by the electroexplosion of metal wire has been practices in the former USSR since the mid 1970`s. Differential scanning calorimetry, differential thermal analysis and x-ray phase analysis was performed on aluminum powder both before and after air passivation, as well as aluminum that was protected under kerosene, pentane, toluene and hexane. Earlier Soviet reports of unexplained thermal releases and metastable behavior have been investigated. Anomalous behavior previously reported included phase transformations at temperatures far below melting with the release of heat and chemoluminescence and self sintering of particles with a heat release large enough to melt the powders.

  13. Phase-controllable synthesis of nanosized nickel phosphides and comparison of photocatalytic degradation ability

    NASA Astrophysics Data System (ADS)

    Ni, Yonghong; Jin, Lina; Hong, Jianming

    2011-01-01

    In this paper, we employed a facile hydrothermal route to successfully synthesize nanosized nickel phosphide particles with controlled phases via selecting different surfactants at different temperatures and times. The phases of the as-obtained products were determined by X-ray powder diffraction (XRD) patterns and Rietveld refinement of XRD data. The morphologies of the products were characterized by (high resolution) transmission electron microscopy (HR/TEM) and field emission scanning electron microscopy (FESEM). Experiments indicated that pure Ni2P phase could be prepared when nontoxic red phosphorus and nickel dichloride were used as starting materials in the presence of polyvinylpyrrolidone (PVP, 30 K), sodium dodecylbenzene sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB) or polyethylene glycol 10000 (PEG-10000) at 160 °C for 10 h. When acrylamide (AM) was selected as the surfactant, however, pure Ni12P5 phase could be prepared by prolonging the reaction time to 20 h at 160 °C, or enhancing the reaction temperature to 180 °C for 10 h. Furthermore, the experiments indicated that the pure Ni2P phase possessed a stronger photocatalytic degradation ability than the pure Ni12P5 phase.

  14. Phase-controllable synthesis of nanosized nickel phosphides and comparison of photocatalytic degradation ability.

    PubMed

    Ni, Yonghong; Jin, Lina; Hong, Jianming

    2011-01-01

    In this paper, we employed a facile hydrothermal route to successfully synthesize nanosized nickel phosphide particles with controlled phases via selecting different surfactants at different temperatures and times. The phases of the as-obtained products were determined by X-ray powder diffraction (XRD) patterns and Rietveld refinement of XRD data. The morphologies of the products were characterized by (high resolution) transmission electron microscopy (HR/TEM) and field emission scanning electron microscopy (FESEM). Experiments indicated that pure Ni2P phase could be prepared when nontoxic red phosphorus and nickel dichloride were used as starting materials in the presence of polyvinylpyrrolidone (PVP, 30 K), sodium dodecylbenzene sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB) or polyethylene glycol 10000 (PEG-10000) at 160 °C for 10 h. When acrylamide (AM) was selected as the surfactant, however, pure Ni12P5 phase could be prepared by prolonging the reaction time to 20 h at 160 °C, or enhancing the reaction temperature to 180 °C for 10 h. Furthermore, the experiments indicated that the pure Ni2P phase possessed a stronger photocatalytic degradation ability than the pure Ni12P5 phase. PMID:21049133

  15. Degradation of simazine from aqueous solutions by diatomite-supported nanosized zero-valent iron composite materials.

    PubMed

    Sun, Zhiming; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L; Xi, Yunfei

    2013-12-15

    A novel composite material based on deposition of nanosized zero-valent iron (nZVI) particles on acid-leached diatomite was synthesised for the removal of a chlorinated contaminant in water. The nZVI/diatomite composites were characterised by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. Compared with the pure nZVI particles, better dispersion of nZVI particles on the surface or inside the pores of diatom shells was observed. The herbicide simazine was selected as the model chlorinated contaminant and the removal efficiency by nZVI/diatomite composite was compared with that of the pristine nZVI and commercial iron powder. It was found that the diatomite supported nZVI composite material prepared by centrifugation exhibits relatively better efficient activity in decomposition of simazine than commercial Fe, lab synthesised nZVI and composite material prepared via rotary evaporation, and the optimum experimental conditions were obtained based on a series of batch experiments. This study on immobilising nZVI particles onto diatomite opens a new avenue for the practical application of nZVI and the diatomite-supported nanosized zero-valent iron composite materials have potential applications in environmental remediation. PMID:24231330

  16. Nanosized Thin SnO2 Layers Doped with Te and TeO2 as Room Temperature Humidity Sensors

    PubMed Central

    Georgieva, Biliana; Podolesheva, Irena; Spasov, Georgy; Pirov, Jordan

    2014-01-01

    In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques—SEM, EDS in SEM, TEM, SAED, AES and electrical measurements—are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio RSn/Te and the evaporation conditions. It is shown that as-deposited layers with RSn/Te ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature—very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties. PMID:24854359

  17. Phase transformations of nano-sized cubic boron nitride to white graphene and white graphite

    SciTech Connect

    Dang, Hongli; Liu, Yingdi; Xue, Wenhua; Anderson, Ryan S.; Sewell, Cody R.; Xue, Sha; Crunkleton, Daniel W.; Shen, Yaogen; Wang, Sanwu

    2014-03-03

    We report quantum-mechanical investigations that predict the formation of white graphene and nano-sized white graphite from the first-order phase transformations of nano-sized boron nitride thin-films. The phase transformations from the nano-sized diamond-like structure, when the thickness d > 1.4 nm, to the energetically more stable nano-sized white graphite involve low activation energies of less than 1.0 eV. On the other hand, the diamond-like structure transforms spontaneously to white graphite when d ≤ 1.4 nm. In particular, the two-dimensional structure with single-layer boron nitride, the so-called white graphene, could be formed as a result of such transformation.

  18. Nanosized Borides and Carbides for Electroplating. Metal-Matrix Coatings: Specifications, Performance Evaluation

    NASA Astrophysics Data System (ADS)

    Galevskiy, G. V.; Rudneva, V. V.; Galevskiy, S. G.; Il’yashchenko, D. P.; Kartsev, D. S.

    2016-04-01

    This paper summarizes experience of application of nano-sized carbides and borides of titanium and chromium, silicon carbide as components of electro-depositable coating compositions based on nickel, zinc, and chromium. Basic physical and mechanical properties of the coatings are determined. Technological and economic evaluation is completed; practicability of high-cost nano-diamonds substitution for nano-sized borides and carbides is justified.

  19. Nanosized particles of orlistat with enhanced in vitro dissolution rate and lipase inhibition.

    PubMed

    Dolenc, Andrej; Govedarica, Biljana; Dreu, Rok; Kocbek, Petra; Srcic, Stane; Kristl, Julijana

    2010-08-30

    Orlistat is locally acting inhibitor of gastrointestinal lipases which has been developed for the treatment of obesity. The present study was designed with the intent to formulate orlistat in a different way compared to the current practice and investigate its inhibition of gastrointestinal lipases. Orlistat is considered as a technologically problematic and unmanageable substance because of waxy nature, low melting point and low chemical stability. The manuscript presents the critical issues regarding engineering of its nanosuspension with controlled particle size by melt emulsification and high pressure homogenization. In order to formulate dry product, lactose was dissolved in nanosuspension as filler and spray drying has been performed for obtaining the final powder product. Laser diffraction, scanning electron microscopy and atomic force microscopy have been used for orlistat nanosuspension characterization, dissolution studies and lipase inhibition studies were performed to characterize the in vitro efficacy of formulated orlistat. The advantage of selected technological procedures is nanosized orlistat with elevated in vitro dissolution rate in comparison to raw drug, physical mixture and marketed product. Furthermore, nanosuspension demonstrated significantly higher in vitro lipase inhibition in comparison to references. To conclude, the results show new technological solution and remarkable increase of pharmacological effect which could potentially lead to decreasing the dose and consequently dose dependent side effects. PMID:20540997

  20. Lattice contraction in nanosized silicon particles produced by laser pyrolysis of silane

    NASA Astrophysics Data System (ADS)

    Hofmeister, H.; Huisken, F.; Kohn, B.

    We used laser-induced decomposition of silane for the fabrication of nanosized Si particles and studied in detail their structural characteristics by conventional and high resolution electron microscopy. The silane gas flow reactor incorporated in a molecular beam apparatus was operated without size selection to achieve a broad size distribution. Deposition at low energy on carbon substrates yielded single crystalline, spherical Si particles almost completely free of planar lattice defects. The particles, covered by thin amorphous oxide shells, are not agglomerated into larger aggregates. The lattice of diamond cubic type exhibits deviations from the bulk spacing which vary from distinct contraction to dilatation as with decreasing particle size the oxide shell thickness is reduced. This effect is discussed in terms of the strong Si/oxide interfacial interaction and compressive stresses arising upon oxidation. A negative interface stress, as determined from the size dependence of the lattice spacing, limits the curvature of the interface, i.e., at small sizes Si oxidation must be considered as a self-limiting process.

  1. Nanosized copper ferrite materials: Mechanochemical synthesis and characterization

    SciTech Connect

    Manova, Elina; Tsoncheva, Tanya; Paneva, Daniela; Popova, Margarita; Velinov, Nikolay; Kunev, Boris; Tenchev, Krassimir; Mitov, Ivan

    2011-05-15

    Nanodimensional powders of cubic copper ferrite are synthesized by two-steps procedure of co-precipitation of copper and iron hydroxide carbonates, followed by mechanochemical treatment. X-ray powder diffraction, Moessbauer spectroscopy and temperature-programmed reduction are used for the characterization of the obtained materials. Their catalytic behavior is tested in methanol decomposition to hydrogen and CO and total oxidation of toluene. Formation of nanosized ferrite material is registered even after one hour of milling time. It is established that the prolonging of treatment procedure decreases the dispersion of the obtained product with the appearance of Fe{sub 2}O{sub 3}. It is demonstrated that the catalytic behavior of the samples depends not only on their initial phase composition, but on the concomitant ferrite phase transformations by the influence of the reaction medium. -- Graphical abstract: It is demonstrated that the catalytic behavior of the obtained copper ferrites depends not only on their initial phase composition, but on the concomitant phase transformations by the influence of the reaction medium. Display Omitted Highlights: {yields} Two-step co-precipitation-ball-milling procedure for copper ferrites preparation. {yields} The phase composition of ferrites depends on the milling duration. {yields} Ferrites transforms under the reaction medium, which affects their catalytic behavior. {yields} Ferrites decompose to magnetite and carbides during methanol decomposition. {yields} Agglomeration and further crystallization of ferrite occur during toluene oxidation.

  2. Electrochemical reaction of lithium with nanosized vanadium antimonate

    SciTech Connect

    Morales, Julian; Sanchez, Luis . E-mail: luis-sanchez@uco.es; Martin, Francisco; Berry, Frank

    2006-08-15

    Nanometric vanadium antimonate, VSbO{sub 4}, was prepared by mechanical milling from Sb{sub 2}O{sub 3} and V{sub 2}O{sub 5} and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbaueer spectroscopy (MS) and X-ray photoelectron spectroscopy (XPS) techniques. Its reactivity towards lithium was examined by testing Li/VSbO{sub 4} cells under galvanostatic and potentiostatic regimes. The amount of Li inserted was found to be consistent with a two-step process involving the reactions (i) VSbO{sub 4}+8 Li{sup {yields}}Sb+V+4 Li{sub 2}O and (ii) Sb+3 Li{sup {yields}}Li{sub 3}Sb, the former being virtually irreversible and the latter reversible as suggested by the shape of the anodic and cathodic curves. Ex situ XPS measurements of the discharged and charged electrode provided direct evidence of the formation of alloyed Sb and confirmed the results of the potentiostatic curves regarding the irreversible or reversible character of the previous reactions. The Li/VSbO{sub 4} cell exhibited acceptable electrochemical performance, which surpassed that of other Sb-based compounds as the likely result of the formation of V and its associated enhanced electrode conductivity. - Graphical abstract: TEM image of nanosized VSbO{sub 4} sample.

  3. Synthesis and Reaction Chemistry of Nanosize Monosodium Titanate.

    PubMed

    Elvington, Mark C; Taylor-Pashow, Kathryn M L; Tosten, Michael H; Hobbs, David T

    2016-01-01

    This paper describes the synthesis and peroxide-modification of nanosize monosodium titanate (nMST), along with an ion-exchange reaction to load the material with Au(III) ions. The synthesis method was derived from a sol-gel process used to produce micron-sized monosodium titanate (MST), with several key modifications, including altering reagent concentrations, omitting a particle seed step, and introducing a non-ionic surfactant to facilitate control of particle formation and growth. The resultant nMST material exhibits spherical-shaped particle morphology with a monodisperse distribution of particle diameters in the range from 100 to 150 nm. The nMST material was found to have a Brunauer-Emmett-Teller (BET) surface area of 285 m(2)g(-1), which is more than an order of magnitude higher than the micron-sized MST. The isoelectric point of the nMST measured 3.34 pH units, which is a pH unit lower than that measured for the micron-size MST. The nMST material was found to serve as an effective ion exchanger under weakly acidic conditions for the preparation of an Au(III)-exchange nanotitanate. In addition, the formation of the corresponding peroxotitanate was demonstrated by reaction of the nMST with hydrogen peroxide. PMID:26967828

  4. Electrophoresis system for high temperature mobility measurements of nanosize particles

    NASA Astrophysics Data System (ADS)

    Rodriguez-Santiago, Victor; Fedkin, Mark V.; Lvov, Serguei N.

    2008-09-01

    The electrophoretic mobility, which reflects the zeta potential of a solid material, is an important experimental quantity providing information about the electrical double layer at the solid/liquid interface. A new high temperature electrophoresis cell was developed suitable for electrophoretic mobility measurements of dispersed nanosize particles up to 150 °C and 40 bars. Amorphous silica (SiO2) particle size standards were used to test the particle size detection limit of the new instrument at 25, 100, and 150 °C and several pH values. The microscopic detection of the particles was enabled by dark-field illumination, which allowed extending the previously available capabilities and provided higher accuracy of the electrophoretic mobility data. The electrophoretic mobility measurements for SiO2 at temperatures above 100 °C were reported for the first time and indicated a gradual increase in particle electrophoretic response with increasing temperature. The obtained data indicated negatively charged SiO2 surface throughout the pH and temperature ranges studied.

  5. Refractive index modification of polymers using nanosized dopants

    NASA Astrophysics Data System (ADS)

    Hanemann, Thomas; Boehm, Johannes; Müller, Claas; Ritzhaupt-Kleissl, Eberhard

    2008-04-01

    The addition of nanosized inorganic or organic dopants to polymers allows the modification of the polymers physical properties enabling the realization of functionalized polymers with new application fields e.g. in microoptics. Exemplarily electron rich organic dopants, solved in polymers, cause a pronounced increase of the refractive index. Polymer based reactive resins like PMMA, solved in MMA, or unsaturated polyester, solved in styrene, can be cured to thermoplastic polymers. The resin's low viscous flow behaviour enables an easy composite formation by solving the organic dopants in the liquid up to a dopant content of 50 wt%, followed by solidification to a thermoplastic. The addition of simple organic molecules like phenanthrene or benzochinoline allows a refractive index elevation at 633 nm from 1.56 up to 1.60 retaining the good transmission properties. In comparison the refractive index of PMMA can be increased from the initial value of 1.49 up to values around 1.58 (@633 nm). All composites show an almost linear correlation between dopant content and refractive index. Using these composites devices like 3dB-couplers or an electrooptical modulator applying injection molded or hot embossed substrates have been realized.

  6. Superfocusing the light through the nanosize slit via photonic tornado

    NASA Astrophysics Data System (ADS)

    Choi, Seong Soo; Jha, Vinaya; Suwal, Om; Park, Myoung Jin; Park, Nam Kyu; Kim, Daisik

    2010-03-01

    The macro size pyramidal horn probe such as klystron horn antenna has been used to provide the excellent focusing capabilities in microwave region. In the similar way, the pyramidal probe with the micron size mirror (pyramidal horn probe) has been fabricated with a nano-size aperture with diameter ranging from ˜1 nm to ˜30 nm. Light transmission through the micro-fabricated pyramidal horn probe has been measured to enhance the light transmission due to resonant effects between the cavity mode and the slit modes in the probe, along with improved directionality of the transmitted beam. The resonant tunneling between two standing waves in the input groove and in the output groove can provide the transmission enhancements. With decreasing slit width, the transmission is found to increasing tremendously.[1] The transmission is measured to be inversely proportional to the area.[2,3] References:[1] R. Gordon, Phys. Rev. B 73, 153405 (2006).[2] R. Harrington, IEEE Trans. Antennas Propagat. Ap-30, 205(1982).[3] Y Leviatan, R. Harrington, J. Maut, IEEE Trans. Antennas Propagat. Ap-30, 1533(1982)

  7. Aloe vera Induced Biomimetic Assemblage of Nucleobase into Nanosized Particles

    PubMed Central

    Chauhan, Arun; Zubair, Swaleha; Sherwani, Asif; Owais, Mohammad

    2012-01-01

    Aim Biomimetic nano-assembly formation offers a convenient and bio friendly approach to fabricate complex structures from simple components with sub-nanometer precision. Recently, biomimetic (employing microorganism/plants) synthesis of metal and inorganic materials nano-particles has emerged as a simple and viable strategy. In the present study, we have extended biological synthesis of nano-particles to organic molecules, namely the anticancer agent 5-fluorouracil (5-FU), using Aloe vera leaf extract. Methodology The 5-FU nano- particles synthesized by using Aloe vera leaf extract were characterized by UV, FT-IR and fluorescence spectroscopic techniques. The size and shape of the synthesized nanoparticles were determined by TEM, while crystalline nature of 5-FU particles was established by X-ray diffraction study. The cytotoxic effects of 5-FU nanoparticles were assessed against HT-29 and Caco-2 (human adenocarcinoma colorectal) cell lines. Results Transmission electron microscopy and atomic force microscopic techniques confirmed nano-size of the synthesized particles. Importantly, the nano-assembled 5-FU retained its anticancer action against various cancerous cell lines. Conclusion In the present study, we have explored the potential of biomimetic synthesis of nanoparticles employing organic molecules with the hope that such developments will be helpful to introduce novel nano-particle formulations that will not only be more effective but would also be devoid of nano-particle associated putative toxicity constraints. PMID:22403622

  8. Preparation of nanosize polyaniline and its utilization for microwave absorber.

    PubMed

    Abbas, S M; Dixit, A K; Chatterjee, R; Goel, T C

    2007-06-01

    Polyaniline powder in nanosize has been synthesized by chemical oxidative route. XRD, FTIR, and TEM were used to characterize the polyaniline powder. Crytallite size was estimated from XRD profile and also ascertained by TEM in the range of 15 to 20 nm. The composite absorbers have been prepared by mixing different ratios of polyaniline into procured polyurethane (PU) binder. The complex permittivity (epsilon' - jepsilon") and complex permeability (mu' - jmu") were measured in X-band (8.2-12.4 GHz) using Agilent network analyzer (model PNA E8364B) and its software module 85071 (version 'E'). Measured values of these parameters were used to determine the reflection loss at different frequencies and sample thicknesses, based on a model of a single layered plane wave absorber backed by a perfect conductor. An optimized polyaniline/PU ratio of 3:1 has given a minimum reflection loss of -30 dB (99.9% power absorption) at the central frequency 10 GHz and the bandwidth (full width at half minimum) of 4.2 GHz over whole X-band (8.2 to 12.4 GHz) in a sample thickness of 3.0 mm. The prepared composites can be fruitfully utilized for suppression of electromagnetic interference (EMI) and reduction of radar signatures (stealth technology). PMID:17655005

  9. Local Electronic And Dielectric Properties at Nanosized Interfaces

    SciTech Connect

    Bonnell, Dawn A.

    2015-02-23

    Final Report to the Department of Energy for period 6/1/2000 to 11/30/2014 for Grant # DE-FG02-00ER45813-A000 to the University of Pennsylvania Local Electronic And Dielectric Properties at Nanosized Interfaces PI: Dawn Bonnell The behavior of grain boundaries and interfaces has been a focus of fundamental research for decades because variations of structure and composition at interfaces dictate mechanical, electrical, optical and dielectric properties in solids. Similarly, the consequence of atomic and electronic structures of surfaces to chemical and physical interactions are critical due to their implications to catalysis and device fabrication. Increasing fundamental understanding of surfaces and interfaces has materially advanced technologies that directly bear on energy considerations. Currently, exciting developments in materials processing are enabling creative new electrical, optical and chemical device configurations. Controlled synthesis of nanoparticles, semiconducting nanowires and nanorods, optical quantum dots, etc. along with a range of strategies for assembling and patterning nanostructures portend the viability of new devices that have the potential to significantly impact the energy landscape. As devices become smaller the impact of interfaces and surfaces grows geometrically. As with other nanoscale phenomena, small interfaces do not exhibit the same properties as do large interfaces. The size dependence of interface properties had not been explored and understanding at the most fundamental level is necessary to the advancement of nanostructured devices. An equally important factor in the behavior of interfaces in devices is the ability to examine the interfaces under realistic conditions. For example, interfaces and boundaries dictate the behavior of oxide fuel cells which operate at extremely high temperatures in dynamic high pressure chemical environments. These conditions preclude the characterization of local properties during fuel cell

  10. Interactions of humic acid with nanosized inorganic oxides.

    PubMed

    Yang, Kun; Lin, Daohui; Xing, Baoshan

    2009-04-01

    Adsorption of natural organic matter (NOM) on nanoparticles (NPs) is important for evaluating their transport, transfer, and fate in the environment, which will also affect sorption of hydrophobic organic compounds (HOCs) by NPs and thereby potentially alter the toxicity of NPs and the fate, transport, and bioavailability of HOCs in the environment. Therefore, the adsorption behavior of humic acids (HA) by four types of nano-oxides (i.e., TiO2, SiO2, Al2O3, and ZnO) was examined in this study to explore their interaction mechanisms using techniques including Fourier transform infrared (FTIR) spectroscopy and elemental, zeta potential, and surface area analyses. Adsorption of HA was observed on nanosized TiO2, Al2O3, and ZnO but not on nano-SiO2. Furthermore, HA adsorption was pH-dependent. HA adsorption by nano-oxides was mainly induced by electrostatic attraction and ligand exchange between HA and nano-oxide surfaces. Surface hydrophilicity and negative charges of nano-oxides affected their adsorption of HA. However, the maxima of HA adsorption on nano-oxides were limited by the surface area of nano-oxides. HA phenolic OH and COOH groups were responsible for its ligand exchange with nano-TiO2 and nano-ZnO, respectively, while either HA COOH or HA phenolic/aliphatic OH was responsible for its ligand exchange with nano-Al2O3. HA adsorption decreased the micropore surface area of nano-oxides but not the external surface area because of the micropore blockage. HA adsorption also decreased the zeta potential of nano-oxides, indicating that HA-coated nano-oxides could be more easily dispersed and suspended and more stable in solution than uncoated ones because of their enhanced electrostatic repulsion. PMID:19708146

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

    SciTech Connect

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

    2007-01-15

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

  12. An agar diffusion study comparing the antimicrobial activity of Nanoseal with some other endodontic sealers.

    PubMed

    Aal-Saraj, Ali Burak; Ariffin, Zaihan; Masudi, Sam'an Malik

    2012-08-01

    The aim of this study was to evaluate the antimicrobial activity of a new experimental nano-hydroxyapatite epoxy resin-based sealer (Nanoseal) with several other commercially available sealers; AH26, Tubliseal, Sealapex and Roekoseal against Enterococcus faecalis, Pseudomonas aeruginosa, Streptococcus mutans, Streptococcus sobrinus and Escherichia coli for up to 7 days. Agar diffusion was used in this study. Fifty Muller-Hinton agar plates were prepared and divided into five experimental groups (n = 10), for each micro-organism. Another 10 agar plates were used as positive and negative controls. Endodontic sealers were tested against each micro-organism. Inhibition zones produced were recorded. The results of this study showed that all test materials exhibited inhibition zones towards the tested micro-organisms for 7 days except for Roekoseal, which showed no inhibition zones. Nanoseal and AH26 exhibited similar zones of inhibition. Significant difference was found between Nanoseal and the other tested sealers (P < 0.001). PMID:22827817

  13. [Influence of nanosize particles of cobalt ferrite on contractile responses of smooth muscle segment of airways].

    PubMed

    Kapilevich, L V; Zaĭtseva, T N; Nosarev, A V; D'iakova, E Iu; Petlina, Z R; Ogorodova, L M; Ageev, B G; Magaeva, A A; Itin, V I; Terekhova, O G; Medvedev, M A

    2012-02-01

    Contractile responses of airways segments of porpoises inhaling nanopowder CoFe2O4 were stidued by means of a mechanographic method. Inhalation of the nanosize particles of CoFe2O4 in vivo and in vitro testing the nanomaterial on isolated smooth muscles led to potentiation histaminergic, cholinergic contractile activity in airways of porpoises and to strengthening of adrenergic relaxing answers. Nanosize particles vary amplitude of hyperpotassium reductions in smooth muscle segments of airways similarly to the effect of depolymerizing drug colchicine. PMID:22650066

  14. Comprehensive understanding of nano-sized particle separation processes using nanoparticle tracking analysis.

    PubMed

    Lawler, Desmond F; Youn, Sungmin; Zhu, Tongren; Kim, Ijung; Lau, Boris L T

    2015-01-01

    The understanding of nano-sized particle separation processes has been limited by difficulties of nanoparticle characterization. In this study, nanoparticle tracking analysis (NTA) was deployed to evaluate the absolute particle size distributions in laboratory scale flocculation and filtration experiments with silver nanoparticles. The results from NTA were consistent with standard theories of particle destabilization and transport. Direct observations of changes in absolute particle size distributions from NTA enhance both qualitative and quantitative understanding of particle separation processes of nano-sized particles. PMID:26676021

  15. Quantitative measurement of argon inside of nano-sized bubbles in ODS steels

    NASA Astrophysics Data System (ADS)

    Klimenkov, M.

    2011-04-01

    Quantitative analysis of Ar gas in nano-sized bubbles in ODS steel was performed using spatially resolved energy-dispersive X-ray spectroscopy. The Ar Kα line was quantified and used for calculation of Ar the concentration (atoms per nm 3) inside 4-38 nm large bubbles. The Ar concentration and pressure inside bubbles were found to depend on the bubble size. The results were compared with a known equilibrium pressure model developed for calculation of He pressure inside nano-sized bubbles. Several investigations were performed to determine the stability of Ar bubbles in the thin TEM foil.

  16. Improved Thermoelectric Performances of SrTiO3 Ceramic Doped with Nb by Surface Modification of Nanosized Titania.

    PubMed

    Li, Enzhu; Wang, Ning; He, Hongcai; Chen, Haijun

    2016-12-01

    Nb-doped SrTiO3 ceramics doped with the surface modification of nanosized titania was prepared via liquid phase deposition approach and subsequent sintered in an Ar atmosphere. The surface modification of nanosized titania significantly improved the ratio of the electrical conductivity to thermal conductivity of SrTiO3 ceramic doped with Nb, and has little impact on the Seebeck coefficient, thus obviously improving the dimensionless thermoelectric figure of merit (ZT value). The surface modification of nanosized titania is a much better method to lower the thermal conductivity and to enhance the electrical conductivity than the mechanical mixing process of nanosized titania. The highest ZT value of 0.33 at 900 K was obtained. The reason for the improved thermoelectric performances by the surface modification of nano-sized titania was preliminary investigated. PMID:27067736

  17. Improved Thermoelectric Performances of SrTiO3 Ceramic Doped with Nb by Surface Modification of Nanosized Titania

    NASA Astrophysics Data System (ADS)

    Li, Enzhu; Wang, Ning; He, Hongcai; Chen, Haijun

    2016-04-01

    Nb-doped SrTiO3 ceramics doped with the surface modification of nanosized titania was prepared via liquid phase deposition approach and subsequent sintered in an Ar atmosphere. The surface modification of nanosized titania significantly improved the ratio of the electrical conductivity to thermal conductivity of SrTiO3 ceramic doped with Nb, and has little impact on the Seebeck coefficient, thus obviously improving the dimensionless thermoelectric figure of merit ( ZT value). The surface modification of nanosized titania is a much better method to lower the thermal conductivity and to enhance the electrical conductivity than the mechanical mixing process of nanosized titania. The highest ZT value of 0.33 at 900 K was obtained. The reason for the improved thermoelectric performances by the surface modification of nano-sized titania was preliminary investigated.

  18. Mixing of nanosize particles by magnetically assisted impaction techniques

    NASA Astrophysics Data System (ADS)

    Scicolone, James V.

    Nanoparticles and nanocomposites offer unique properties that arise from their small size, large surface area, and the interactions of phases at their interfaces, and are attractive for their potential to improve performance of drugs, biomaterials, catalysts and other high-value-added materials. However, a major problem in utilizing nanoparticles is that they often lose their high surface area due to grain growth. Creating nanostructured composites where two or more nanosized constituents are intimately mixed can prevent this loss in surface area, but in order to obtain homogeneous mixing, de-agglomeration of the individual nanoparticle constituents is necessary. Due to high surface area, nano-particles form very large, fractal agglomerates. The structure of these agglomerates can have a large agglomerate composed of sub-agglomerates (SA), which itself consists of primary agglomerates (PA), that contain chain or net like nano-particle structures; typically sub-micron size. Thus the final agglomerate has a hierarchical, fractal structure, and depending upon the forces applied, it could break down to a certain size scale. The agglomerates can be fairly porous and fragile or they could be quite dense, based on primary particle size and its surface energy. Thus depending upon the agglomerate strength at different length scales, one could achieve deagglomeration and subsequent mixing at varying length scale. A better understanding of this can have a major impact on the field of nano-structured materials; thus the long term objective of this project is to gain fundamental understanding of deagglomeration and mixing of nano-agglomerates. Dry mixing is in general not effective in achieving desired mixing at nanoscale, whereas wet mixing suffers from different disadvantages like nanomaterial of interest should be insoluble, has to wet the liquid, and involves additional steps of filtration and drying. This research examines the use of environmentally friendly a novel

  19. Ultrafast synthesis of nano-sized zeolite SAPO-34 with excellent MTO catalytic performance.

    PubMed

    Sun, Qiming; Wang, Ning; Guo, Guanqi; Yu, Jihong

    2015-11-25

    Nano-sized SAPO-34 zeolites with high crystallinity are obtained in 10 minutes by fast heating the reaction gel in a stainless steel tubular reactor combined with the seed-assisted method, which show outstanding performance in methanol-to-olefin (MTO) reaction. PMID:26412585

  20. NANOSIZE TITANIA STIMULATES REACTIVE OXYGEN SPECIES IN BRAIN MICROGLIA AND DAMAGES NEURONS.

    EPA Science Inventory

    Research that addresses the environmental impact and biological consequences of widely distributed, commonly used nanoparticles is needed. Nanosize titanium dioxide (i.e., titania, TiO2) is used in air and water remediation and in numerous products designed for direct human us...

  1. Creation of deep blue light emitting nitrogen-vacancy center in nanosized diamond

    SciTech Connect

    Himics, L. Tóth, S.; Veres, M.; Koós, M.; Balogh, Z.

    2014-03-03

    This paper reports on the formation of complex defect centers related to the N3 center in nanosized diamond by employing plasma immersion and focused ion beam implantation methods. He{sup +} ion implantation into nanosized diamond “layer” was performed with the aim of creating carbon atom vacancies in the diamond structure, followed by the introduction of molecular N{sub 2}{sup +} ion and heat treatment in vacuum at 750 °C to initiate vacancy diffusion. To decrease the sp{sup 2} carbon content of nanosized diamond formed during the implantation processes, a further heat treatment at 450 °C in flowing air atmosphere was used. The modification of the bonding properties after each step of defect creation was monitored by Raman scattering measurements. The fluorescence measurements of implanted and annealed nanosized diamond showed the appearance of an intensive and narrow emission band with fine structures at 2.98 eV, 2.83 eV, and 2.71 eV photon energies.

  2. TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS

    EPA Science Inventory

    TRANSPORT AND DEPOSITION OF NANO-SIZE PARTICLES IN THE UPPER HUMAN RESPIRATORY AIRWAYS. Zhe Zhang*, Huawei Shi, Clement Kleinstreuer, Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910; Chong S. Kim, National Health and En...

  3. Cancer Drug Delivery: Considerations in the Rational Design of Nanosized Bioconjugates

    PubMed Central

    2015-01-01

    In order to efficiently deliver anticancer agents to tumors, biocompatible nanoparticles or bioconjugates, including antibody–drug conjugates (ADCs), have recently been designed, synthesized, and tested, some even in clinical trials. Controlled delivery can be enhanced by changing specific design characteristics of the bioconjugate such as its size, the nature of the payload, and the surface features. The delivery of macromolecular drugs to cancers largely relies on the leaky nature of the tumor vasculature compared with healthy vessels in normal organs. When administered intravenously, macromolecular bioconjugates and nanosized agents tend to circulate for prolonged times, unless they are small enough to be excreted by the kidney or stealthy enough to evade the macrophage phagocytic system (MPS), formerly the reticulo-endothelial system (RES). Therefore, macromolecular bioconjugates and nanosized agents with long circulation times leak preferentially into tumor tissue through permeable tumor vessels and are then retained in the tumor bed due to reduced lymphatic drainage. This process is known as the enhanced permeability and retention (EPR) effect. However, success of cancer drug delivery only relying on the EPR effect is still limited. To cure cancer patients, further improvement of drug delivery is required by both designing superior agents and enhancing EPR effects. In this Review, we describe the basis of macromolecular or nanosized bioconjugate delivery into cancer tissue and discuss current diagnostic methods for evaluating leakiness of the tumor vasculature. Then, we discuss methods to augment conventional “permeability and retention” effects for macromolecular or nanosized bioconjugates in cancer tissue. PMID:25385142

  4. In Situ Transmission Electron Microscopy Heating Studies of Particle Coalescence and Microstructure Evolution in Nanosized Ceramics

    SciTech Connect

    2006-06-02

    Final report on in-situ transmission microscopy heating studies of particle coalescence and microstructure evolution in nanosized ceramics. Report includes summary of work on particle shape changes and stress effects, and novel infiltration techniques in the processing of alumina based ceramics.

  5. Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries

    DOEpatents

    Deng, Haixia; Belharouak, Ilias; Amine, Khalil

    2012-10-02

    Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0

  6. Atomic scale study of magnetic phase transitions in (Co,Ti;Sc) substituted nanosize barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Krezhov, Kiril

    BaFe12O19 and related isostructural (M-type) hexaferrites derived by single or double cation substitution for Fe3+ with preservation of the formal valence are a recognized group of oxides for their remarkable properties. The magnetic interactions may be tuned by suitable substitutions resulting in notable magnetic properties utilized extensively for permanent magnets, microwave devices and perpendicular recording media. We report on the magnetic structure evolution accompanying the magnetic anisotropy change, from a combined magnetic (SQUID), x-ray and neutron diffraction, and magnetic field dependent 57Fe Mössbauer study on BaFe12O19 at selected cation substitutions. The short and long range atomic and magnetic order in powder samples of nanosize particles prepared by soft chemistry routes were studied and compared with own and literature data for the parent BaFe12O19 compound prepared by solid state reaction. Refinements based on diffraction data show that the magnetic structures of BaFe12-xXxO19 (X=Co,Ti; Sc) hexaferrites are largely temperature and substitution dependent. Between 200 and 300K the (Co,Ti)-hexaferrites (x=0.4, 0.7, 0.8, 0.85) display ferrimagnetic structures where the canting of the magnetic moments depends on the substitution rate. When lowering the temperature the magnetic structure for x=0.45 remains ferrimagnetic down to 10 K, while for x=0.7 and x=0.8 a complex conical magnetic structures is finally established. For x=0.85 significant distortions in the local oxygen surrounding of ferric cation sites were established, while the grain-size effect on the structural parameters was considerably smaller. The thermal expansion coefficient exhibits a strong anisotropy. The refined magnetic moments are considerably lower than the theoretical spin only moments, especially for the 4e and 12k sites, indicating a local noncollinearity with short-range ordering. The five-cation sublattice collinear ferrimagnetic structure of uniaxial type known as

  7. Innate defence functions of macrophages can be biased by nano-sized ceramic and metallic particles.

    PubMed

    Lucarelli, Marilena; Gatti, Antonietta M; Savarino, Graziana; Quattroni, Paola; Martinelli, Lucia; Monari, Emanuela; Boraschi, Diana

    2004-01-01

    Nano-sized particles of ceramic and metallic materials are generated by high-tech industrial activities, and can be generated from worn-out replacement and prosthetic implants. The interaction with the human body of such nanoparticles has been investigated, with a particular emphasis on innate defence mechanisms. Human macrophages (PMA-differentiated myelomonocytic U-937 cells) were exposed in vitro to non-toxic concentrations of TiO(2), SiO(2), ZrO(2), or Co nanoparticles, and their inflammatory response (expression of TLR receptors and co-receptors, and cytokine production) was examined. Expression of TLR receptors was generally unaffected by exposure to the different nanoparticles, except for some notable cases. Exposure to nanoparticles of ZrO(2) (and to a lesser extent TiO(2)), upregulated expression of viral TLR receptors TLR3 and TLR7. Expression of TLR10 was also increased by TiO(2) and ZrO(2) nanoparticles. On the other hand, TLR9 expression was decreased by SiO(2) nano-particles, and expression of the co-receptor CD14 was inhibited by Co nanoparticles. Basal and LPS-induced production of cytokines IL-1beta, TNF-alpha, and IL-1Ra was examined in macrophages exposed to nanoparticles. SiO(2) nanoparticles strongly biased naive macrophages towards inflammation (M1 polarisation), by selectively inducing production of inflammatory cytokines IL-1beta and TNF-alpha. SiO(2) nanoparticles also significantly amplified the inflammatory phenotype of LPS-polarised M1 macrophages. Other ceramic nanoparticles had little influence on cytokine production, either in resting macrophages, or in LPS-activated cells. Generally, Co nanoparticles had an overall pro-inflammatory effect on naive macrophages, by reducing anti-inflammatory IL-1Ra and inducing inflammatory TNF-alpha. However, Co nanoparticles reduced production of IL-1beta and IL-1Ra, but not TNF-alpha, in LPS-polarised M1 macrophages. Thus, exposure to different nanoparticles can modulate, in different ways, the

  8. Investigation on the red shift of charge transfer excitation spectra for nano-sized Y 2O 3:Eu 3+

    NASA Astrophysics Data System (ADS)

    Shang, Chunyu; Shang, Xiaohong; Qu, Yuqiu; Li, Meicheng

    2011-01-01

    Based upon the local structure data, the differences of energy bands between bulk and nano-sized Y2O3:Eu3+ have been presented. The volume expansion in nano-sized Y2O3:Eu3+ leads to the shrinkage of band gap and decrease of zero-phonon charge transfer (CT) energy; the enlargement of local disorder in nano-sized Y2O3:Eu3+ leads to the formation of impurity bands and further decrease of zero-phonon CT energy. On the basis of the differences in energy bands, the mechanisms for the decrease of CT energy, i.e., red shift of CT excitation spectra for nano-sized Y2O3:Eu3+ have been clarified.

  9. Hierarchically micro-patterned nanofibrous scaffolds with a nanosized bio-glass surface for accelerating wound healing

    NASA Astrophysics Data System (ADS)

    Xu, He; Lv, Fang; Zhang, Yali; Yi, Zhengfang; Ke, Qinfei; Wu, Chengtie; Liu, Mingyao; Chang, Jiang

    2015-11-01

    A composite scaffold with a controlled micro-pattern, nano-sized fiber matrix and surface-modified nanobioglass component was successfully prepared for skin wound healing by combining the patterning electrospinning with pulsed laser deposition strategies, and the hierarchical micro/nano structures and nano-sized bioglass in the scaffolds could synergistically improve the efficiency and re-epithelialization of wound healing.A composite scaffold with a controlled micro-pattern, nano-sized fiber matrix and surface-modified nanobioglass component was successfully prepared for skin wound healing by combining the patterning electrospinning with pulsed laser deposition strategies, and the hierarchical micro/nano structures and nano-sized bioglass in the scaffolds could synergistically improve the efficiency and re-epithelialization of wound healing. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04802h

  10. Hierarchically micro-patterned nanofibrous scaffolds with a nanosized bio-glass surface for accelerating wound healing.

    PubMed

    Xu, He; Lv, Fang; Zhang, Yali; Yi, Zhengfang; Ke, Qinfei; Wu, Chengtie; Liu, Mingyao; Chang, Jiang

    2015-11-28

    A composite scaffold with a controlled micro-pattern, nano-sized fiber matrix and surface-modified nanobioglass component was successfully prepared for skin wound healing by combining the patterning electrospinning with pulsed laser deposition strategies, and the hierarchical micro/nano structures and nano-sized bioglass in the scaffolds could synergistically improve the efficiency and re-epithelialization of wound healing. PMID:26503372

  11. Preparation of nano-sized nickel as anode catalyst for direct urea and urine fuel cells

    NASA Astrophysics Data System (ADS)

    Lan, Rong; Tao, Shanwen

    Nano-sized nickel with primary particle size of 2-3 nm has been successfully prepared for use as efficient anode catalysts in urea and urine fuel cells. XRD, SEM and TEM were used for characterisation of nano-sized nickel. Based on the previous communication, the performance of urea and urine fuel cells has been further improved when the relative humidity at the cathode was 100%. A maximum power density of 14.2 mW cm -2 was achieved when 1 M urea was used as fuel, humidified air as oxidant. The performance of urine fuel cells operating above room temperature was also reported for the first time and a power density of 4.23 mW cm -2 was achieved at 60 °C indicating potential application in urea-rich waste water treatment.

  12. Current inversions induced by resonant coupling to surface waves in a nanosized water pump.

    PubMed

    Zhou, Xiaoyan; Wu, Fengmin; Liu, Yang; Kou, Jianlong; Lu, Hui; Lu, Hangjun

    2015-11-01

    We conducted a molecular dynamics simulation to investigate current inversions in a nanosized water pump based on a single-walled carbon nanotube powered by mechanical vibration. It was found that the water current depended sensitively on the frequency of mechanical vibration. Especially in the resonance region, the nanoscale pump underwent reversals of the water current. This phenomenon was attributed to the dynamics competition of the water molecules in the two sections (the left and right parts) divided by the vibrating atom and the differences in phase and decay between the two mechanical waves generated by mechanical vibration and propagating in opposite directions toward the two ends of the carbon nanotube. Our findings provide an insight into water transportation through nanosized pumps and have potential in the design of high-flux nanofluidic systems and nanoscale energy converters. PMID:26651789

  13. New synthesis of nanosized niobium oxides and lithium niobate particles and their characterization by XPS analysis.

    PubMed

    Aufray, Maëlenn; Menuel, Stéphane; Fort, Yves; Eschbach, Julien; Rouxel, Didier; Vincent, Brice

    2009-08-01

    This work presents a new synthesis of nano-sized lithium niobate particles by a low temperature three steps procedure. The complete protocol implies a LiH induced reduction of NbCl5 followed by in situ spontaneous oxidation into low valence niobium nano-oxides. These niobium oxides are exposed to air atmosphere leading to pure Nb2O5 formation. Finally, the stable Nb2O5 is converted into lithium niobate LiNbO3 nanoparticles during the controlled hydrolysis of the LiH excess. The nano-sized lithium niobate particles as well as their formation processes were characterized using X-ray photoelectron spectroscopy. PMID:19928149

  14. Photocatalytic activity of nanosized TiO2 thin film prepared by magnetron sputtering method.

    PubMed

    Kang, Sang-Jun; Kim, Ki-Joong; Chung, Min-Chul; Jung, Sang-Chul; Boo, Su-Il; Cho, Soon Kye; Jeong, Woon-Jo; Ahn, Ho-Geun

    2011-02-01

    Nanosized TiO2 thin film on the substrate such as stainless steel plate and slide glass film were prepared by magnetron sputtering method, and these TiO2 thin films were characterized by field emission-scanning electron microscopy (FE-SEM). Photocatalytic activity for Methyl-ethyl-ketone (MEK) and acetaldehyde were measured using a closed circulating reaction system through the various ultra violet (UV) sources. From the results of SEM images, nanosized TiO2 thin film was uniformly coated on slide glass, ranging from 360 nm to 370 nm. Photocatalytic activity of MEK over TiO2 thin film on stainless steel plate did not occur by UV-A irradiation, but was efficiently decomposed by UV-B and UV-C. Also, acetaldehyde could be decomposed than MEK. The effect of sputtering conditions on their structure and photocatalytic activities were investigated in detail. PMID:21456269

  15. Synthesis, Characterization, and Catalytic Properties of Novel Single-Site and Nanosized Platinum Catalysts

    SciTech Connect

    Bonati, Matteo L.M.; Douglas, Thomas M.; Gaemers, Sander; Guo, Neng

    2013-01-10

    Novel single-site platinum catalysts have been synthesized by reacting platinum(II) organometallics with partially dehydroxylated silica. The resulting materials have been characterized by various methods such as IR, MAS NMR, and EXAFS. Further, the single-site platinum catalysts were calcined in air to remove the ligand and produce nanosized platinum particles, that were characterized by TEM and H{sub 2} chemisorption. All catalysts were tested for the hydrogenation of toluene. The single-site platinum catalysts were less active than a commercial Pt/SiO{sub 2} catalyst with comparable platinum loading, and this has been ascribed to ligand effects. Conversely, the nanosized platinum catalysts were more active than the commercial Pt/SiO{sub 2} catalyst due to their high dispersion and small particle sizes.

  16. Effect of an upward magnetic field on nanosized sulfide precipitation in ultra-low carbon steel

    NASA Astrophysics Data System (ADS)

    Duan, Kang-jia; Zhang, Ling; Yuan, Xi-zhi; Han, Shan-shan; Liu, Yu; Huang, Qing-song

    2015-07-01

    An induction levitation melting (ILM) refining process is performed to remove most microsized inclusions in ultra-low carbon steel (UCS). Nanosized, spheroid shaped sulfide precipitates remain dispersed in the UCS. During the ILM process, the UCS is molten and is rotated under an upward magnetic field. With the addition of Ti additives, the spinning molten steel under the upward magnetic field ejects particles because of resultant centrifugal, floating, and magnetic forces. Magnetic force plays a key role in removing sub-micrometer-sized particles, composed of porous aluminum titanate enwrapping alumina nuclei. Consequently, sulfide precipitates with sizes less than 50 nm remain dispersed in the steel matrix. These findings open a path to the fabrication of clean steel or steel bearing only a nanosized strengthening phase.

  17. Current inversions induced by resonant coupling to surface waves in a nanosized water pump

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoyan; Wu, Fengmin; Liu, Yang; Kou, Jianlong; Lu, Hui; Lu, Hangjun

    2015-11-01

    We conducted a molecular dynamics simulation to investigate current inversions in a nanosized water pump based on a single-walled carbon nanotube powered by mechanical vibration. It was found that the water current depended sensitively on the frequency of mechanical vibration. Especially in the resonance region, the nanoscale pump underwent reversals of the water current. This phenomenon was attributed to the dynamics competition of the water molecules in the two sections (the left and right parts) divided by the vibrating atom and the differences in phase and decay between the two mechanical waves generated by mechanical vibration and propagating in opposite directions toward the two ends of the carbon nanotube. Our findings provide an insight into water transportation through nanosized pumps and have potential in the design of high-flux nanofluidic systems and nanoscale energy converters.

  18. Penetration, photo-reactivity and photoprotective properties of nanosized ZnO.

    PubMed

    Detoni, C B; Coradini, K; Back, P; Oliveira, C M; Andrade, D F; Beck, R C R; Pohlmann, A R; Guterres, S S

    2014-09-01

    The oxidizing capacity and skin penetration of a commercial nanosized ZnO, Nanosun™ (Micronisers-Australia), were evaluated in vitro using porcine skin. Nanosun™ was initially characterized regarding its photo-reactivity and size distribution. An assay using methylene blue was performed to confirm the Nanosun™ photo-reactivity by exposing the labile molecule to UVA irradiation in the presence and absence of the nanosized ZnO. The nanosized ZnO was photo-reactive, reducing the methylene blue concentration to 7% while its concentration remained constant in the control formulation (without ZnO). The product label states that the average particle size is 30 nm. X-ray diffraction, nitrogen sorption and UV-spectrophotometry confirmed the presence of nanometric particles of approximately 30 nm. On the other hand, laser diffractometry showed micrometric particles in the size distribution profile. These analyses indicated that the nanoparticles are arranged as agglomerates and aggregates of micrometric proportions ranging from 0.6 to 60 μm. The skin lipid peroxidation was determined by the formation of thiobarbituric acid reactive species (TBARS) and quantified by UV-spectrophotometry. When exposed to UVA radiation the nanosized ZnO applied porcine skin showed a lower production of TBARS (7.2 ± 1.5 nmol g(-1)) than the controls, the MCT applied porcine skin (18.4 ± 2.8 nmol g(-1)) and the blank porcine skin (14.0 ± 2.0 nmol g(-1)). The penetration of ZnO nanoparticles was studied by scanning electron microscopy and energy dispersive X-ray spectroscopy. The tested ZnO particles did not penetrate into viable layers of the intact porcine skin. The particles tend to accumulate on the skin folds and in these regions they may penetrate into the horny layer. PMID:24977261

  19. Gas promotes the crystallization of nano-sized metal-organic frameworks in ionic liquid.

    PubMed

    Liu, Chengcheng; Zhang, Bingxing; Zhang, Jianling; Peng, Li; Kang, Xinchen; Han, Buxing; Wu, Tianbin; Sang, Xinxin; Ma, Xue

    2015-07-21

    Herein it was found that gas can be utilized as an activator to promote metal-organic framework (MOF) crystallization in IL at room temperature. The ultra-small MOF nanoparticles were obtained, and their size and porosity properties can be easily modulated by controlling gas pressure. The as-synthesized nano-sized Cu-MOF is an excellent candidate catalyst for the solvent-free oxidation of cyclohexene with oxygen. PMID:26087458

  20. Nano-sized polystyrene affects feeding, behavior and physiology of brine shrimp Artemia franciscana larvae.

    PubMed

    Bergami, Elisa; Bocci, Elena; Vannuccini, Maria Luisa; Monopoli, Marco; Salvati, Anna; Dawson, Kenneth A; Corsi, Ilaria

    2016-01-01

    Nano-sized polymers as polystyrene (PS) constitute one of the main challenges for marine ecosystems, since they can distribute along the whole water column affecting planktonic species and consequently disrupting the energy flow of marine ecosystems. Nowadays very little knowledge is available on the impact of nano-sized plastics on marine organisms. Therefore, the present study aims to evaluate the effects of 40nm anionic carboxylated (PS-COOH) and 50nm cationic amino (PS-NH2) polystyrene nanoparticles (PS NPs) on brine shrimp Artemia franciscana larvae. No signs of mortality were observed at 48h of exposure for both PS NPs at naplius stage but several sub-lethal effects were evident. PS-COOH (5-100μg/ml) resulted massively sequestered inside the gut lumen of larvae (48h) probably limiting food intake. Some of them were lately excreted as fecal pellets but not a full release was observed. Likewise, PS-NH2 (5-100µg/ml) accumulated in larvae (48h) but also adsorbed at the surface of sensorial antennules and appendages probably hampering larvae motility. In addition, larvae exposed to PS-NH2 undergo multiple molting events during 48h of exposure compared to controls. The activation of a defense mechanism based on a physiological process able to release toxic cationic NPs (PS-NH2) from the body can be hypothesized. The general observed accumulation of PS NPs within the gut during the 48h of exposure indicates a continuous bioavailability of nano-sized PS for planktonic species as well as a potential transfer along the trophic web. Therefore, nano-sized PS might be able to impair food uptake (feeding), behavior (motility) and physiology (multiple molting) of brine shrimp larvae with consequences not only at organism and population level but on the overall ecosystem based on the key role of zooplankton on marine food webs. PMID:26422775

  1. Fabrication of Discrete Nanosized Cobalt Particles Encapsulated Inside Single-Walled Carbon Nanotubes

    SciTech Connect

    Zoican Loebick, C.; Majewska, M; Ren, F; Haller, G; Pfefferle, L

    2010-01-01

    Single-walled carbon nanotubes (SWNT) with encapsulated nanosized cobalt particles have been synthesized by a facile and scalable method. In this approach, SWNT were filled with a cobalt acetylacetonate solution in dichloromethane by ultrasonication. In a second step, exposure to hydrogen at different temperatures released discrete cobalt particles of controllable size inside the SWNT cavity. The SWNT-Co particles systems were characterized by transmission electron microscopy, X-ray absorption spectroscopy, Raman spectroscopy, and thermal gravimetric analysis.

  2. Effect of nano-SiC on the sintering behavior and properties of calcined carbon derived from mesocarbon microbeads

    NASA Astrophysics Data System (ADS)

    Xia, Hongyan; Wang, Jiping; Liu, Guiwu; Shi, Zhongqi; Qiao, Guanjun

    2010-08-01

    Calcined carbon materials derived from mesocarbon microbeads (MCMBs) with or without pre-oxidative treatment were prepared and the effect of doped nano-SiC powder on the sintering behavior and properties was investigated. The results showed that the sintering shrinkage and density increment of the samples doped with 5 wt.% nano-SiC were higher than those with 3 wt.% and 10 wt.%, due to the amount of defects and extent of graphitization controlled by the content of nano-SiC. Physical and mechanical properties improved remarkably after doping a certain amount of nano-SiC. The highest bending strength of 122 MPa and lowest electric resistivity of 28 μΩ m were obtained when doping 5 wt.% nano-SiC in green MCMBs. Ball-milling contributed to reduction of particle sizes of MCMBs/nano-SiC mixtures and hence reduced or eliminated the gaps between particles in the calcined materials. The catalytic effect of nano-SiC can promote particle rearrangement and structure improvement during the sintering.

  3. Colloidally stable surface-modified iron oxide nanoparticles: Preparation, characterization and anti-tumor activity

    NASA Astrophysics Data System (ADS)

    Macková, Hana; Horák, Daniel; Donchenko, Georgiy Viktorovich; Andriyaka, Vadim Ivanovich; Palyvoda, Olga Mikhailovna; Chernishov, Vladimir Ivanovich; Chekhun, Vasyl Fedorovich; Todor, Igor Nikolaevich; Kuzmenko, Oleksandr Ivanovich

    2015-04-01

    Maghemite (γ-Fe2O3) nanoparticles were obtained by co-precipitation of Fe(II) and Fe(III) chlorides and subsequent oxidation with sodium hypochlorite and coated with poly(N,N-dimethylacrylamide-co-acrylic acid) [P(DMAAm-AA)]. They were characterized by a range of methods including transmission electron microscopy (TEM), elemental analysis, dynamic light scattering (DLS) and zeta potential measurements. The effect of superparamagnetic P(DMAAm-AA)-γ-Fe2O3 nanoparticles on oxidation of blood lipids, glutathione and proteins in blood serum was detected using 2-thiobarbituric acid and the ThioGlo fluorophore. Finally, mice received magnetic nanoparticles administered per os and the antitumor activity of the particles was tested on Lewis lung carcinoma (LLC) in male mice line C57BL/6 as an experimental in vivo metastatic tumor model; the tumor size was measured and the number of metastases in lungs was determined. Surface-modified γ-Fe2O3 nanoparticles showed higher antitumor and antimetastatic activities than commercial CuFe2O4 particles and the conventional antitumor agent cisplatin.

  4. Highly efficient solvent-free synthesis of 1,3-diacylglycerols by lipase immobilised on nano-sized magnetite particles.

    PubMed

    Meng, Xiao; Xu, Gang; Zhou, Qin-Li; Wu, Jian-Ping; Yang, Li-Rong

    2014-01-15

    Recently, 1,3-DAGs (1,3-diacylglycerols) have attracted considerable attention as healthy components of food, oil and pharmaceutical intermediates. Generally, 1,3-DAG is prepared by lipase-mediated catalysis in a solvent free system. However, the system's high reaction temperature (required to reach the reactants' melting point), high substrate concentration and high viscosity severely reduce the lipase's activity, selectivity and recycling efficiency. In this report, MjL (Mucor javanicus lipase) was found to have the best performance in the solvent-free synthesis of 1,3-DAGs of several common commercial lipases. By covalent binding to amino-group-activated NSM (nano-sized magnetite) particles and cross-linking to form an enzyme aggregate coat, MjL's specific activity increased 10-fold, and was able to be reused for 10 cycles with 90% residual activity at 55°C. 1,3-DAGs of lauric, myristic, palmitic, stearic, oleic and linoleic acid were prepared using the resulting immobilised enzyme, all with yields greater than 90%, and the reaction time was also greatly reduced. PMID:24054246

  5. A LOW-COST PROCESS FOR THE SYNTHESIS OF NANOSIZE YTTRIA-STABILIZED ZIRCONIA (YSZ) BY MOLECULAR DECOMPOSITION

    SciTech Connect

    Anil V. Virkar

    2004-05-06

    This report summarizes the results of work done during the performance period on this project, between October 1, 2002 and December 31, 2003, with a three month no-cost extension. The principal objective of this work was to develop a low-cost process for the synthesis of sinterable, fine powder of YSZ. The process is based on molecular decomposition (MD) wherein very fine particles of YSZ are formed by: (1) Mixing raw materials in a powder form, (2) Synthesizing compound containing YSZ and a fugitive constituent by a conventional process, and (3) Selectively leaching (decomposing) the fugitive constituent, thus leaving behind insoluble YSZ of a very fine particle size. While there are many possible compounds, which can be used as precursors, the one selected for the present work was Y-doped Na{sub 2}ZrO{sub 3}, where the fugitive constituent is Na{sub 2}O. It can be readily demonstrated that the potential cost of the MD process for the synthesis of very fine (or nanosize) YSZ is considerably lower than the commonly used processes, namely chemical co-precipitation and combustion synthesis. Based on the materials cost alone, for a 100 kg batch, the cost of YSZ made by chemical co-precipitation is >$50/kg, while that of the MD process should be <$10/kg. Significant progress was made during the performance period on this project. The highlights of the progress are given here in a bullet form. (1) From the two selected precursors listed in Phase I proposal, namely Y-doped BaZrO{sub 3} and Y-doped Na{sub 2}ZrO{sub 3}, selection of Y-doped Na{sub 2}ZrO{sub 3} was made for the synthesis of nanosize (or fine) YSZ. This was based on the potential cost of the precursor, the need to use only water for leaching, and the short time required for the process. (2) For the synthesis of calcia-stabilized zirconia (CSZ), which has the potential for use in place of YSZ in the anode of SOFC, Ca-doped Na{sub 2}ZrO{sub 3} was demonstrated as a suitable precursor. (3) Synthesis of Y

  6. Nanosize Mn{sub 3}O{sub 4} (Hausmannite) by microwave irradiation method

    SciTech Connect

    Apte, S.K.; Naik, S.D.; Sonawane, R.S.; Kale, B.B. . E-mail: kbbb1@yahoo.com; Pavaskar, Neela; Mandale, A.B.; Das, B.K.

    2006-03-09

    The present investigation reports, the novel synthesis of nanosize Mn{sub 3}O{sub 4} powder with nanorods using microwaves and its physicochemical characterization. The nanosize Mn{sub 3}O{sub 4} powder has been prepared using manganese nitrate as a precursor and effect of ethanolamine and ethylenediamine on particle morphology has been studied. The microwave irradiation has been carried out in the range 50-500 W and it was observed that formation of Mn{sub 3}O{sub 4} takes place at 50 W. TEM analysis demonstrated nanosize Mn{sub 3}O{sub 4} powder and nanorods with an average diameter of about 10 nm. The structural study by XRD indicates that these nano-powders have pure tetragonal phase. The phase pure samples were characterized using X-Ray Photoelectron Spectroscopy (XPS) for both Mn 2p and Mn 3s levels. The values of binding energies are consistent with the relative values reported in the literature. The metallic impurity levels have been characterized using Inductively Coupled Plasma-Optical Emission Spectrophotometer (ICP-OES)

  7. [Synergistic effects of nano-sized magnetic particles and uncoupler to the characteristics of activated sludge].

    PubMed

    Gao, Li-ying; Tang, Bing; Liang, Ling-yan; Huang, Shao-song; Fu, Feng-lian; Luo, Jian-zhong

    2012-08-01

    For improving the performance and sludge settling property of an activated sludge reduction process with uncoupler, in this investigation, uncoupler and nano-sized magnetic particles were added simultaneously to a sequencing batch reactor for exploring their synergistic effects to the characteristics of activated sludge. The results showed that the volume reduction of sludge reached 41% with single 2,4,5-Trichlorophenol (TCP) Comparing with the control experiment, the biodegradability and settling properties of the activated sludge decreased. Under the actions of TCP combined with nano-sized magnetic particles, the volume reduction of sludge reached 34%, the removal efficiencies of COD, nitrogen, and phosphorus as well as the sludge settling property were not significantly influenced. After 31 d's operation, the dehydrogenase activity was improved by 10%-18% and exhibited an accumulative effect over time. It was observed with an optical microscope that the species and amounts of protozoon and metazoan increased and a compact structure of sludge floc was formed. The results also indicated that using nano-sized magnetic particles and uncoupler could restrict the yield of excess sludge and improve the performance of an activated sludge system. PMID:23213903

  8. Effect of nano-sized oxide particles on thermal and electrical properties of epoxy silica composites

    NASA Astrophysics Data System (ADS)

    Lee, Sang Heon; Choi, Yong

    2014-12-01

    Polymer matrix composites were fabricated using a modified injection molding technique in which nano-sized silicon oxides, titanium oxides, and aluminium oxides were contained. Nano-sized oxides were uniformly distributed in the composites produced by modified injection molding combining vacuum degassing and curing at a moderate temperature. The thermal decomposition and evaporation of the epoxy resin matrix depended on the composition of the composites. The relative permittivity of the nano-sized silicon carbide-epoxy composites increased from 5.16 to 5.37 by adding 2.0 wt % titanium oxide. The addition of titanium oxide of up to 2.0 wt % had little influence on the permittivity. The addition of 2.0 wt % of titanium oxide to epoxy resin showed the maximum thermal properties. Both the thermal conductivity and thermal diffusivity of the silicon oxide-epoxy composites tended to increase with titanium oxide content. The maximum thermal conductivity was observed in the composites with 2.0 wt % titanium oxide.

  9. Nano-sized manganese oxides as biomimetic catalysts for water oxidation in artificial photosynthesis: a review

    PubMed Central

    Najafpour, Mohammad Mahdi; Rahimi, Fahimeh; Aro, Eva-Mari; Lee, Choon-Hwan; Allakhverdiev, Suleyman I.

    2012-01-01

    There has been a tremendous surge in research on the synthesis of various metal compounds aimed at simulating the water-oxidizing complex (WOC) of photosystem II (PSII). This is crucial because the water oxidation half reaction is overwhelmingly rate-limiting and needs high over-voltage (approx. 1 V), which results in low conversion efficiencies when working at current densities required for hydrogen production via water splitting. Particular attention has been given to the manganese compounds not only because manganese has been used by nature to oxidize water but also because manganese is cheap and environmentally friendly. The manganese–calcium cluster in PSII has a dimension of about approximately 0.5 nm. Thus, nano-sized manganese compounds might be good structural and functional models for the cluster. As in the nanometre-size of the synthetic models, most of the active sites are at the surface, these compounds could be more efficient catalysts than micrometre (or bigger) particles. In this paper, we focus on nano-sized manganese oxides as functional and structural models of the WOC of PSII for hydrogen production via water splitting and review nano-sized manganese oxides used in water oxidation by some research groups. PMID:22809849

  10. Design and Evaluation of Multi-functional Nanocarriers for Selective Delivery of Coenzyme Q10 to Mitochondria

    PubMed Central

    Sharma, Anjali; Soliman, Ghareb M.; Al-Hajaj, Noura; Sharma, Rishi; Maysinger, Dusica; Kakkar, Ashok

    2016-01-01

    Impairments of mitochondrial functions have been associated with failure of cellular functions in different tissues leading to various pathologies. We report here a mitochondria–targeted nanodelivery system for coenzyme Q10 (CoQ10) which can reach mitochondria, and deliver CoQ10 in adequate quantities. Multifunctional nanocarriers based on ABC miktoarm polymers (A= PEG, B = polycaprolactone (PCL) and C = triphenylphosphonium bromide (TPPBr)) were synthesized using a combination of click chemistry with ring opening polymerization, self-assembled into nano-sized micelles, and were employed for CoQ10-loading. Drug loading capacity (60 weight%), micelle size (25–60 nm) and stability were determined using a variety of techniques. The micelles had a small critical association concentration, and were colloidally stable in solution for more than 3 months. The extraordinarily high CoQ10 loading capacity in the micelles is attributed to good compatibility between CoQ10 and PCL, as indicated by low Flory-Huggins interaction parameter. Confocal microscopy studies of fluorescently labeled polymer analog together with the mitochondria-specific vital dye label, indicated that the carrier did indeed reach mitochondria. The high CoQ10 loading efficiency allowed testing of micelles within a broad concentration range, and provided evidence for CoQ10 effectiveness in two different experimental paradigms: oxidative stress and inflammation. Combined results from chemical, analytical and biological experiments suggest that the new miktoarm-based carrier provides a suitable means of CoQ10 delivery to mitochondria without loss of drug effectiveness. The versatility of the click chemistry used to prepare this new mitochondria-targeting nanocarrier offers a widely applicable, simple and easily reproducible procedure to deliver drugs to mitochondria or other intracellular organelles. PMID:22148549

  11. Nanosized CuO and ZnO Catalyst Supported on Honeycomb-Typed Monolith for Hydrogenation of Carbon Dioxide to Methyl Alcohol.

    PubMed

    Park, Chul-Min; Ahn, Won-Ju; Jo, Woong-Kyu; Song, Jin-Hun; Oh, Chang-Yeop; Jeong, Young-Shin; Chung, Min-Chul; Park, Kwon-Pil; Kim, Ki-Joong; Jeong, Woon-Jo; Sohn, Bo-Kyun; Jung, Sang-Chul; Lee, Do-Jin; Ahn, Byeong-Kwon; Ahn, Ho-Geun

    2015-01-01

    The greenhouse effect of carbon dioxide (CO2) has been recognized as one of the most serious problems in the world. Conversion of CO2 to methyl alcohol (CH3OH) was studied using catalytic chemical methods. Honeycomb-typed monolith used as catalyst support was 400 cell/inch2. Pretreatment of the monolith surface was carried out by thermal treatment and acid treatment. Monolith-supported nanosized CuO-ZnO catalysts were prepared by wash-coat method. The prepared catalysts were characterized by using SEM, TEM, and XRD. The catalytic activity for CO2 hydrogenation to CH3OH was investigated using a flow-type reactor with varying reaction temperature, reaction pressure and contact time. Conversion of CO2 was increased with increasing reaction temperature, but selectivity to CH3OH was decreased. Optimum reaction temperature was about 250 degrees C under 20 atm. Because of the reverse water gas shift reaction. PMID:26328404

  12. Accelerated methanogenesis from effluents of hydrogen-producing stage in anaerobic digestion by mixed cultures enriched with acetate and nano-sized magnetite particles.

    PubMed

    Yang, Zhiman; Xu, Xiaohui; Guo, Rongbo; Fan, Xiaolei; Zhao, Xiaoxian

    2015-08-01

    Potential for paddy soil enrichments obtained in the presence of nano-sized magnetite particles (named as PSEM) to promote methane production from effluents of hydrogen-producing stage in two-stage anaerobic digestion was investigated. The results showed that the addition of magnetite significantly accelerated methane production from acetate in a dose-independent manner. The results from high-throughput sequencing analysis revealed that Rhodocyclaceae-related species were selectively enriched, which were likely the key players for conversion of acetate to methane in PSEM. Compared to the paddy soil enrichments obtained in the absence of magnetite (named as PSEC), the maximum methane production rate in PSEM was significantly higher (1.5-5.5times higher for the artificial medium and 0.2-1.7times higher for the effluents). The accelerated methane production from the effluents indicated remarkably application potential of PSEM for improving performance of anaerobic digestion. PMID:25935393

  13. In vitro spectroscopic study of piperine-encapsulated nanosize liposomes.

    PubMed

    Pentak, Danuta

    2016-03-01

    Black pepper is a source of effective antioxidants. It contains several powerful antioxidants and is thus one of the most important spices for preventing and curtailing oxidative stress. There is considerable interest in the development of a drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic and amphiphilic molecules. This article focuses on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress. Liposome formulations of piperine were analyzed with various spectroscopic methods. The formulation with the highest entrapment efficiency (90.5%) was formulated with an L-α-phosphatidylcholine dipalmitoyl (DPPC):piperine, 30:1 molar ratio, and total lipid count of 19.47 mg/ml in the final liposomal preparation. The liposome formulation was found to be stable after storage at 4 °C, protected from light, for a minimum of 3 weeks. The incremental process of piperine penetration through the phospholipid membrane was analyzed using the FT-IR, UV-Vis and NMR methods. Temperature stability studies carried out at 37 °C showed the highest percentage of piperine release in the first 3 h of incubation. PMID:26493066

  14. Comparing the calcium bioavailability from two types of nano-sized enriched milk using in-vivo assay.

    PubMed

    Erfanian, Arezoo; Rasti, Babak; Manap, Yazid

    2017-01-01

    Calcium bioavailability from two types of enriched (calcium citrate and calcium carbonate) milks homogenized to a nano-sized particle distribution has been studied among 48 female Sprauge-dawley rats. Skim milk powder was enriched with some essential nutrients (Inulin, DHA & EPA, vitamins B6, K1, and D3) as enhancers of calcium bioavailability according to recommended dietary allowances of the West European and North American. Ovariectomized and ovariectomized-osteoporosis rats were used as a menopause and menopause-osteoporosis model, respectively. Although, nano-sized enriched milk powders had the greatest calcium bioavailability among the groups, but bioavailability of nano-sized calcium carbonate-enriched-milk was significantly (P<0.05) better than nano-sized calcium citrate-enriched-milk. Moreover, the trends were similar for bone calcium, strength and morphology. Therefore, based on the current results the calcium carbonate nano-sized enriched milk could be an effective enriched milk powder in ovariectomized-osteoporosis and ovariectomized rats as a model of menopause-osteoporosis and menopause women. PMID:27507516

  15. Nano-sized cosmetic formulations or solid nanoparticles in sunscreens: a risk to human health?

    PubMed

    Nohynek, Gerhard J; Dufour, Eric K

    2012-07-01

    Personal care products (PCP) often contain micron- or nano-sized formulation components, such as nanoemulsions or microscopic vesicles. A large number of studies suggest that such vesicles do not penetrate human skin beyond the superficial layers of the stratum corneum. Nano-sized PCP formulations may enhance or reduce skin absorption of ingredients, albeit at a limited scale. Modern sunscreens contain insoluble titanium dioxide (TiO₂) or zinc oxide (ZnO) nanoparticles (NP), which are efficient filters of UV light. A large number of studies suggest that insoluble NP do not penetrate into or through human skin. A number of in vivo toxicity tests, including in vivo intravenous studies, showed that TiO₂ and ZnO NP are non-toxic and have an excellent skin tolerance. Cytotoxicity, genotoxicity, photo-genotoxicity, general toxicity and carcinogenicity studies on TiO₂ and ZnO NP found no difference in the safety profile of micro- or nano-sized materials, all of which were found to be non-toxic. Although some published in vitro studies on insoluble nano- or micron-sized particles suggested cell uptake, oxidative cell damage or genotoxicity, these data are consistent with those from micron-sized particles and should be interpreted with caution. Data on insoluble NP, such as surgical implant-derived wear debris particles or intravenously administered magnetic resonance contrast agents suggest that toxicity of small particles is generally related to their chemistry rather than their particle size. Overall, the weight of scientific evidence suggests that insoluble NP used in sunscreens pose no or negligible risk to human health, but offer large health benefits, such as the protection of human skin against UV-induced skin ageing and cancer. PMID:22466067

  16. Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics

    PubMed Central

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Khan, Abdul Samad; Zohaib, Sana; Martí, Juan Manuel Nuñez; Sauro, Salvatore; Matinlinna, Jukka Pekka; Rehman, Ihtesham Ur

    2016-01-01

    Glass ionomer cements (GICs) are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1–100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs) can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties. PMID:27428956

  17. Comparison of radiation shielding ratios of nano-sized bismuth trioxide and molybdenum

    NASA Astrophysics Data System (ADS)

    Cho, J. H.; Kim, M. S.; Rhim, J. D.

    2015-07-01

    In this study, radiation shielding fibers using non-hazardous nano-sized bismuth trioxide and molybdenum instead of lead were developed and evaluated. Among the elements with high densities and atomic numbers, non-hazardous elements such as bismuth trioxide and molybdenum were chosen as a shielding element. Then, bismuth trioxide (Bi2O3) with average particle size 1-500 µm was ball milled for 10 min to produce a powdered form of nanoparticles with average particle size of 10-100 nm. Bismuth trioxide nanoparticles were dispersed to make a colloidal suspension, followed by spreading and hardening onto one or two sides of fabric, to create the radiation shielding fabric. The thicknesses of the shielding sheets using nano-sized bismuth and molybdenum were 0.4 and 0.7 mm. According to the lead equivalent test of X-ray shielding products suggested by KS, the equivalent dose was measured, followed by calculation of the shielding rate. The shielding rate of bismuth with 0.4 mm thickness and at 50 kVp was 90.5%, which is comparable to lead of 0.082 mm thickness. The shielding rate of molybdenum was 51.89%%, which is comparable to lead of 0.034 mm. At a thickness of 0.7 mm, the shielding rate of bismuth was 98.73%, equivalent to 0.101 mm Pb, whereas the shielding rate of molybdenum was 74.68%, equivalent to 0.045 mm Pb. In conclusion, the radiation shielding fibers using nano-sized bismuth developed in this study are capable of reducing radiation exposure by X-ray and its low-dose scatter ray.

  18. Modifications in Glass Ionomer Cements: Nano-Sized Fillers and Bioactive Nanoceramics.

    PubMed

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Khan, Abdul Samad; Zohaib, Sana; Martí, Juan Manuel Nuñez; Sauro, Salvatore; Matinlinna, Jukka Pekka; Rehman, Ihtesham Ur

    2016-01-01

    Glass ionomer cements (GICs) are being used for a wide range of applications in dentistry. In order to overcome the poor mechanical properties of glass ionomers, several modifications have been introduced to the conventional GICs. Nanotechnology involves the use of systems, modifications or materials the size of which is in the range of 1-100 nm. Nano-modification of conventional GICs and resin modified GICs (RMGICs) can be achieved by incorporation of nano-sized fillers to RMGICs, reducing the size of the glass particles, and introducing nano-sized bioceramics to the glass powder. Studies suggest that the commercially available nano-filled RMGIC does not hold any significant advantage over conventional RMGICs as far as the mechanical and bonding properties are concerned. Conversely, incorporation of nano-sized apatite crystals not only increases the mechanical properties of conventional GICs, but also can enhance fluoride release and bioactivity. By increasing the crystallinity of the set matrix, apatites can make the set cement chemically more stable, insoluble, and improve the bond strength with tooth structure. Increased fluoride release can also reduce and arrest secondary caries. However, due to a lack of long-term clinical studies, the use of nano-modified glass ionomers is still limited in daily clinical dentistry. In addition to the in vitro and in vivo studies, more randomized clinical trials are required to justify the use of these promising materials. The aim of this paper is to review the modification performed in GIC-based materials to improve their physicochemical properties. PMID:27428956

  19. Hydrothermal synthesis of nanosize phases based on non-ferrous and noble metals

    NASA Astrophysics Data System (ADS)

    Tupikova, E. N.; Platonov, I. A.; Lykova, T. N.

    2016-04-01

    Research is devoted to reactions of binary complexes containing noble (platinum, palladium) and non-ferrous (cobalt, chrome) metals. Reactions proceed under hydrothermal conditions by the autoclave technique. Initials complexes and products of autoclave thermolysis were characterized by the FT-IR spectroscopy, the transmission electron microscopy (TEM) and the energy-dispersive X-ray spectroscopy (EDX). Comparative catalytic experiments in the test reaction were conducted. The obtained results can form the basis of new methods of nanosize multicomponent phases synthesis under hydrothermal conditions.

  20. Phase-Slip Avalanches in the Superflow of {sup 4}He through Arrays of Nanosize Apertures

    SciTech Connect

    Pekker, David; Barankov, Roman; Goldbart, Paul M.

    2007-04-27

    In response to recent experiments by the Berkeley group, we construct a model of superflow through an array of nanosize apertures that incorporates two basic ingredients: (1) disorder associated with each aperture having its own random critical velocity, and (2) effective interaperture coupling, mediated through the bulk superfluid. As the disorder becomes weak there is a transition from a regime where phase slips are largely independent to a regime where interactions lead to system-wide avalanches of phase slips. We explore the flow dynamics in both regimes, and make connections to the experiments.

  1. Nano-sized fine droplets of liquid crystals for optical application

    SciTech Connect

    Matsumoto, Shiro; Houlbert, M.; Hayashi, Takayoshi; Kubodera, Kenichi

    1997-09-01

    Nano-sized fine droplets of liquid crystal (LC) were obtained by phase separation of nematic LC in UV curing polymer. The polymer composite had a high transparency in the infrared region. The fine droplets responded to an electric field causing a change in birefringence. Output power change was brought about by the generated retardation between two polarizations, parallel and perpendicular to the applied electric field. This differs from the composite containing much larger droplets, where output depends on the degree of scattering. The birefringence changed by 0.001 at the applied voltage of 7.5 V/{micro}m.

  2. Enhancement of hybrid rocket combustion performance using nano-sized energetic particles

    NASA Astrophysics Data System (ADS)

    Risha, Grant Alexander

    Until now, the regression rate of classical hybrid rocket engines have typically been an order of magnitude lower than solid propellant motors; thus, hybrids require a relatively large fuel surface area for a given thrust level. In addition to low linear regression rates, relatively low combustion efficiency (87 to 92%), low mass burning rates, varying oxidizer-to-fuel ratio during operation, and lack of scaling laws have been reported. These disadvantages can be ameliorated by introducing nano-sized energetic powder additives into the solid fuel. The addition of nano-sized energetic particles into the solid fuel enhances performance as measured by parameters such as: density specific impulse, mass and linear burning rates, and thrust. Thermophysical properties of the solid fuel such as density, heat of combustion, thermal diffusivity, and thermal conductivity are also enhanced. The types of nano-sized energetic particles used in this study include aluminum, boron, boron carbide, and some Viton-A coated particles. Since the combustion process of solid fuels in a hybrid rocket engine is governed by the mass flux of the oxidizer entering the combustion chamber, the rate-limiting process is the mixing and reacting of the pyrolysis products of the fuel grain with the incoming oxidizer. The overall goal of this research was to determine the relative propulsive and combustion behavior for a family of newly-developed HTPB-based solid-fuel formulations containing various nano-sized energetic particles. Seventeen formulations contained 13% additive by weight, one formulation (SF4) contained 6.5% additive by weight, and one formulation (SF19) contained 5.65% boron by weight. The two hybrid rocket engines which were used in this investigation were the Long Grain Center-Perforated (LGCP) rocket engine and the X-Ray Transparent Casing (XTC) rocket engine. The smaller scale LGCP rocket engine was used to evaluate all of the formulations because conducting experiments using the

  3. Improvement of Dispersibility of Nanosize Diamond by Sonochemical Reaction—Relationships among Acoustic Intensity, Disaggregation, and Surface Modification—

    NASA Astrophysics Data System (ADS)

    Uchida, Takeyoshi; Hamano, Akiko; Kawashima, Norimichi; Takeuchi, Shinichi

    2005-06-01

    Aggregated nanosize diamond particles were disaggregated and had their surfaces modified by ultrasound exposure. A standing wave sound field was formed in a water tank using a Langevin-type transducer. Acoustic cavitation was generated in the water tank. Aggregated nanosize diamond particles with sizes of about 5 μm were disaggregated in particles with sizes of 40 nm by ultrasound exposure for 20 min. The magnitude of the zeta potential on nanosize diamond particles was increased by more than twice by ultrasound exposure. The sound field in the water tank was measured using a hydrophone. The average acoustic intensity was calculated from measured values of sound pressure. The zeta potential began to increase with increasing average acoustic intensity of more than 800 W/m2.

  4. Formation of nanosized monolayer MoS2 by oxygen-assisted thinning of multilayer MoS2

    NASA Astrophysics Data System (ADS)

    Neupane, Guru P.; Dhakal, Krishna P.; Kim, Hyun; Lee, Jubok; Kim, Min Su; Han, Ganghee; Lee, Young Hee; Kim, Jeongyong

    2016-08-01

    We report the controllable nanosized local thinning of multi-layer (2 L and 3 L)-thickness MoS2 films down to the monolayer (1 L) thickness using the simple method of annealing in a dry oxygen atmosphere. The annealing temperature was optimized in the range of 240 °C to 270 °C for 1.5 h, and 1 L thick nanosized pits were developed on the uniform film of the 2 L and 3 L MoS2 grown using the chemical vapor deposition method. We characterized the formation of the 1 L nanosized pits using nanoscale confocal photoluminescence (PL) and Raman spectroscopy. We observed that the PL intensity increased and the Raman frequency shifted, representative of the characteristics of 1 L MoS2 films. A subsequent hydrogen treatment process was useful for removing the oxygen-induced doping effect resulting from the annealing.

  5. Synthesis of nanosize MCM-41 loaded with TiO 2 and study of its photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sadjadi, M. S.; Farhadyar, N.; Zare, K.

    2009-07-01

    In recent years, nanosized mesoporous materials have received significant attention due to their impact in different processes. Several diverse applications of these materials, e.g. high density magnetic recording, magnetic fluids, magnetic refrigeration as well as in photocatalysis, solar cells, photosensors, have triggered considerable research activities in the area of nanotechnology. In this work, nanosize MCM-41 was synthesized and loaded then with TiO 2 using tetra butoxy titanium (TBT). As prepared TiO 2 loaded materials was investigated by using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). The photocatalytic activity of the prepared TiO 2 loaded MCM-41 was finally evaluated by the degradation of methyl orange under irradiation of UV light. The result showed that TiO 2 loaded on nanosize MCM-41 has higher photocatalytic activity than that of TiO 2.

  6. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO2 particles

    NASA Astrophysics Data System (ADS)

    Cui, Chaopeng; Gao, Yimin; Wei, Shizhong; Zhang, Guoshang; Zhou, Yucheng; Zhu, Xiangwei; Guo, Songliang

    2016-03-01

    The nano-sized ZrO2-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO2 particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO2 particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO2 particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %.

  7. Spongelike Nanosized Mn3O4 as a High-Capacity Anode Material for Rechargeable Lithium Batteries

    SciTech Connect

    Gao, Jie; Lowe, Michael A.; Abruna, Hector D.

    2011-07-12

    Mn₃O₄ has been investigated as a high-capacity anode material for rechargeable lithium ion batteries. Spongelike nanosized Mn₃O₄ was synthesized by a simple precipitation method and characterized by powder X-ray diffraction, Raman scattering and scanning electron microscopy. Its electrochemical performance, as an anode material, was evaluated by galvanostatic discharge–charge tests. The results indicate that this novel type of nanosized Mn₃O₄ exhibits a high initial reversible capacity (869 mA h/g) and significantly enhanced first Coulomb efficiency with a stabilized reversible capacity of around 800 mA h/g after over 40 charge/discharge cycles.

  8. Enhancement of oral bioavailability of an HIV-attachment inhibitor by nanosizing and amorphous formulation approaches.

    PubMed

    Fakes, Michael G; Vakkalagadda, Blisse J; Qian, Feng; Desikan, Sridhar; Gandhi, Rajesh B; Lai, Chiajen; Hsieh, Alice; Franchini, Miriam K; Toale, Helen; Brown, Jonathan

    2009-03-31

    BMS-488043 is an HIV-attachment inhibitor that exhibited suboptimal oral bioavailability upon using conventional dosage forms prepared utilizing micronized crystalline drug substance. BMS-488043 is classified as a Biopharmaceutics Classification System (BCS) Class-II compound with a poor aqueous solubility of 0.04mg/mL and an acceptable permeability of 178nm/s in the Caco2 cell-line model. Two strategies were evaluated to potentially enhance the oral bioavailability of BMS-488043. The first strategy targeted particle size reduction through nanosizing the crystalline drug substance. The second strategy aimed at altering the drug's physical form by producing an amorphous drug. Both strategies provided an enhancement in oral bioavailability in dogs as compared to a conventional formulation containing the micronized crystalline drug substance. BMS-488043 oral bioavailability enhancement was approximately 5- and 9-folds for nanosizing and amorphous formulation approaches, respectively. The stability of the amorphous coprecipitated drug prepared at different compositions of BMS-488043/polyvinylpyrrolidone (PVP) was evaluated upon exposure to stressed stability conditions of temperature and humidity. The drastic effect of exposure to humidity on conversion of the amorphous drug to crystalline form was observed. Additionally, the dissolution behavior of coprecipitated drug was evaluated under discriminatory conditions of different pH values to optimize the BMS-488043/PVP composition and produce a stabilized, amorphous BMS-488043/PVP (40/60, w/w) spray-dried intermediate (SDI), which was formulated into an oral dosage form for further development and evaluation. PMID:19100319

  9. Fine cathode particles prepared by solid-state reaction method using nano-sized precursor particles

    NASA Astrophysics Data System (ADS)

    Ju, Seo Hee; Kang, Yun Chan

    Fine-sized Li-Co-Mn-O cathode particles with various ratios of cobalt and manganese components were prepared by conventional solid-state reaction method using the nano-sized precursor particles. The nano-sized precursor particles of cobalt and manganese components were prepared by spray pyrolysis. The LiCo 1- xMn xO 2 (0.1 ≤ x ≤ 0.3) particles had finer size than that of the pure LiCoO 2 particles. Manganese component disturbed the growth of the LiCo 1- xMn xO 2 cathode particles prepared by solid-state reaction method. The pure LiCoO 2 cathode particles had high initial discharge capacity of 144 mAh g -1. However, the initial discharge capacities of the LiCo 1- xMn xO 2 (0.1 ≤ x ≤ 0.3) cathode particles decreased with increasing the contents of the manganese component. The discharge capacities of the LiMn 2- yCo yO 4 (0 ≤ y ≤ 0.2) cathode particles decreased abruptly with increasing the contents of the cobalt component. The pure LiMn 2O 4 cathode particles had the initial discharge capacities of 119 mAh g -1.

  10. Gehlenite:Eu3+ phosphors from a silicone resin and nano-sized fillers

    NASA Astrophysics Data System (ADS)

    Bernardo, E.; Fiocco, L.; Prnová, A.; Klement, R.; Galusek, D.

    2014-05-01

    Gehlenite (Ca2Al2SiO7) ceramics have been successfully prepared by a novel approach, consisting of the heat treatment of a silicone resin embedding CaO and Al2O3 precursors, in the form of nano-sized particles that act as reactive fillers. Luminescence was due to the use of nano-sized Eu2O3 as secondary additive, particularly adopting a charge compensation formulation, i.e. Ca2-2xEu2xAl(Al1+2xSi1-2xO7), with x = 0.07. The phase development and the emission characteristics could be adjusted by simply changing the thermal treatment applied to powders of silicone/fillers mixtures. While conventional firing at 1300 °C (for 1 h) led to practically phase-pure crystalline Eu-doped gehlenite, exhibiting a strong red luminescence, flame synthesis yielded amorphous powders, exhibiting an emission in a much broader range. When excited at 394 nm both gehlenite glass and polycrystalline gehlenite emitted light, which CIE chromaticity coordinates were found to be (x = 0.65, y = 0.35), indicating that both systems are good candidates for red light emitting phosphors.

  11. Nanosize effects assisted synthesis of the high pressure metastable phase in ZrO2

    NASA Astrophysics Data System (ADS)

    Li, Quanjun; Zhang, Huafang; Liu, Ran; Liu, Bo; Li, Dongmei; Zheng, Lirong; Liu, Jing; Cui, Tian; Liu, Bingbing

    2016-01-01

    The size effects on the high pressure behaviors of monoclinic (MI) ZrO2 nanoparticles were studied using in situ high pressure synchrotron X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). A size-dependent phase transition behavior under high pressure was found in nanoscale ZrO2. The normal phase transition sequence of MI-orthorhombic I (OI)-orthorhombic II (OII) occurs in 100-300 nm ZrO2 nanoparticles, while only the transition of MI-OI exists in ultrafine ~5 nm ZrO2 nanoparticles up to the highest experimental pressure of ~52 GPa. This indicates that the size effects preclude the transition from the OI to the OII phase in ~5 nm nanoparticles. Upon decompression, the OII and OI phases are retained down to ambient pressure, respectively. This is the first observation of the pure OI phase ZrO2 under ambient conditions. The bulk moduli of the MI ZrO2 nanoparticles were determined to be B0 = 192 (7) GPa for the 100-300 nm nanoparticles and B0 = 218 (12) GPa for the ~5 nm nanoparticles. We suggest that the significant high surface energy precludes the transition from the OI to the OII phase and the nanosize effects enhance the incompressibility in the ultrafine ZrO2 nanoparticles (~5 nm). Our study indicates that this is a potential way of preparing novel nanomaterials with high pressure structures using nanosize effects.

  12. Fabrication of nano-sized grains by pulsed laser surface melting

    NASA Astrophysics Data System (ADS)

    Wang, Chengtao; Zhou, Hong; lin, Pengyu; Sun, Na; Guo, Qingchen; Yu, Jiaxiang; Wang, Mingxing; Zhao, Yu; Ren, Luquan

    2010-03-01

    In this work, the formation and characterization of nano-sized grains on the modified surfaces of GCr15 and H13 steels have been investigated. The material was processed by pulsed laser surface melting (LSM) under different depths of de-ionized water. The microstructures and phases of the melted zones were examined by x-ray diffraction, environmental field emission scanning electron microscopy and high resolution transmission electron microscopy. The results indicate that LSM under water can successfully fabricate nano-scaled grains on the surfaces of steel, due to the rapid solidification and crystallization by heterogeneous nucleation. The elemental segregation of chromium and activated heterogeneous nucleation mechanism of austenite in liquid metal play a key role in the formation of nano-sized grains at high cooling rates. This one-step technique provides us a new way to prepare uniform nano-scaled grains, and is of great importance for further understanding the growth of nano-materials under extreme conditions.

  13. Phytotoxicity of ionic, micro- and nano-sized iron in three plant species.

    PubMed

    Libralato, G; Costa Devoti, A; Zanella, M; Sabbioni, E; Mičetić, I; Manodori, L; Pigozzo, A; Manenti, S; Groppi, F; Volpi Ghirardini, A

    2016-01-01

    Potential environmental impacts of engineered nanoparticles (ENPs) can be understood taking into consideration phytotoxicity. We reported on the effects of ionic (FeCl3), micro- and nano-sized zerovalent iron (nZVI) about the development of three macrophytes: Lepidium sativum, Sinapis alba and Sorghum saccharatum. Four toxicity indicators (seed germination, seedling elongation, germination index and biomass) were assessed following exposure to each iron concentration interval: 1.29-1570mg/L (FeCl3), 1.71-10.78mg/L (micro-sized iron) and 4.81-33,560mg/L (nano-iron). Exposure effects were also observed by optical and transmission electron microscopy. Results showed that no significant phytotoxicity effects could be detected for both micro- and nano-sized zerovalent irons, including field nanoremediation concentrations. Biostimulation effects such as an increased seedling length and biomass production were detected at the highest exposure concentrations. Ionic iron showed slight toxicity effects only at 1570mg/L and, therefore, no median effect concentrations were determined. By microscopy, ENPs were not found in palisade cells or xylem. Apparently, aggregates of nZVI were found inside S. alba and S. saccharatum, although false positives during sample preparation cannot be excluded. Macroscopically, black spots and coatings were detected on roots of all species especially at the most concentrated treatments. PMID:26232851

  14. Microbial surfactants: fundamentals and applicability in the formulation of nano-sized drug delivery vectors.

    PubMed

    Rodrigues, Ligia R

    2015-07-01

    Microbial surfactants, so-called biosurfactants, comprise a wide variety of structurally distinct amphipathic molecules produced by several microorganisms. Besides exhibiting surface activity at the interfaces, these molecules present powerful characteristics including high biodegradability, low toxicity and special biological activities (e.g. antimicrobial, antiviral, anticancer, among others), that make them an alternative to their chemical counterparts. Several medical-related applications have been suggested for these molecules, including some reports on their potential use in the formulation of nano-sized drug delivery vectors. However, despite their promises, due to the generalized lack of knowledge on microbial surfactants phase behavior and stability under diverse physicochemical conditions, these applications remain largely unexplored, thus representing an exciting field of research. These nano-sized vectors are a powerful approach towards the current medical challenges regarding the development of efficient and targeted treatments for several diseases. In this review, a special emphasis will be given to nanoparticles and microemulsions. Nanoparticles are very auspicious as their size, shape and stability can be manipulated by changing the environmental conditions. On the other hand, the easiness of formulation, as well as the broad possibilities of administration justifies the recent popularity of the microemulsions. Notwithstanding, both vector types still require further developments to overcome some critical limitations related with toxicity and costs, among others. Such developments may include the search for other system components, as the microbial surfactants, that can display improved features. PMID:25655712

  15. Heavy metal removal from water/wastewater by nanosized metal oxides: a review.

    PubMed

    Hua, Ming; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming; Lv, Lu; Zhang, Quanxing

    2012-04-15

    Nanosized metal oxides (NMOs), including nanosized ferric oxides, manganese oxides, aluminum oxides, titanium oxides, magnesium oxides and cerium oxides, provide high surface area and specific affinity for heavy metal adsorption from aqueous systems. To date, it has become a hot topic to develop new technologies to synthesize NMOs, to evaluate their removal of heavy metals under varying experimental conditions, to reveal the underlying mechanism responsible for metal removal based on modern analytical techniques (XAS, ATR-FT-IR, NMR, etc.) or mathematical models, and to develop metal oxide-based materials of better applicability for practical use (such as granular oxides or composite materials). The present review mainly focuses on NMOs' preparation, their physicochemical properties, adsorption characteristics and mechanism, as well as their application in heavy metal removal. In addition, porous host supported NMOs are particularly concerned because of their great advantages for practical application as compared to the original NMOs. Also, some magnetic NMOs were included due to their unique separation performance. PMID:22018872

  16. Nano-sized Superlattice Clusters Created by Oxygen Ordering in Mechanically Alloyed Fe Alloys

    PubMed Central

    Hu, Yong-Jie; Li, Jing; Darling, Kristopher A.; Wang, William Y.; VanLeeuwen, Brian K.; Liu, Xuan L.; Kecskes, Laszlo J.; Dickey, Elizabeth C.; Liu, Zi-Kui

    2015-01-01

    Creating and maintaining precipitates coherent with the host matrix, under service conditions is one of the most effective approaches for successful development of alloys for high temperature applications; prominent examples include Ni- and Co-based superalloys and Al alloys. While ferritic alloys are among the most important structural engineering alloys in our society, no reliable coherent precipitates stable at high temperatures have been found for these alloys. Here we report discovery of a new, nano-sized superlattice (NSS) phase in ball-milled Fe alloys, which maintains coherency with the BCC matrix up to at least 913 °C. Different from other precipitates in ferritic alloys, this NSS phase is created by oxygen-ordering in the BCC Fe matrix. It is proposed that this phase has a chemistry of Fe3O and a D03 crystal structure and becomes more stable with the addition of Zr. These nano-sized coherent precipitates effectively double the strength of the BCC matrix above that provided by grain size reduction alone. This discovery provides a new opportunity for developing high-strength ferritic alloys for high temperature applications. PMID:26134420

  17. Nanosized rods agglomerates as a new approach for formulation of a dry powder inhaler

    PubMed Central

    Salem, HF; Abdelrahim, ME; Eid, K Abo; Sharaf, MA

    2011-01-01

    Background: Nanosized dry powder inhalers provide higher stability for poorly water-soluble drugs as compared with liquid formulations. However, the respirable particles must have a diameter of 1–5 μm in order to deposit in the lungs. Controlled agglomeration of the nanoparticles increases their geometric particle size so they can deposit easily in the lungs. In the lungs, they fall apart to reform nanoparticles, thus enhancing the dissolution rate of the drugs. Theophylline is a bronchodilator with poor solubility in water. Methods: Nanosized theophylline colloids were formed using an amphiphilic surfactant and destabilized using dilute sodium chloride solutions to form the agglomerates. Results: The theophylline nanoparticles thus obtained had an average particle size of 290 nm and a zeta potential of −39.5 mV, whereas the agglomerates were 2.47 μm in size with a zeta potential of −28.9 mV. The release profile was found to follow first-order kinetics (r2 > 0.96). The aerodynamic characteristics of the agglomerated nanoparticles were determined using a cascade impactor. The behavior of the agglomerate was significantly better than unprocessed raw theophylline powder. In addition, the nanoparticles and agglomerates resulted in a significant improvement in the dissolution of theophylline. Conclusion: The results obtained lend support to the hypothesis that controlled agglomeration strategies provide an efficient approach for the delivery of poorly water-soluble drugs into the lungs. PMID:21383856

  18. Kinetics and mechanism of arsenate removal by nanosized iron oxide-coated perlite.

    PubMed

    Mostafa, M G; Chen, Yen-Hua; Jean, Jiin-Shuh; Liu, Chia-Chuan; Lee, Yao-Chang

    2011-03-15

    This study discussed the adsorption kinetics of As(V) onto nanosized iron oxide-coated perlite. The effects of pH, initial concentration of As(V) and common anions on the adsorption efficiency were also investigated. It was observed that a 100% As(V) adsorption was achieved at pH value of 4-8 from the initial concentration containing 1.0 mg-As(V)L(-1) and the adsorption percentage depended on the initial concentration; the phosphate and silicate ions would not interfere with the adsorption efficiency. Furthermore, nanosized iron oxide-coated perlite (IOCP) has been shown to be an effective adsorbent for the removal of arsenate from water. The adsorption kinetics were studied using pseudo-first- and pseudo-second-order models, and the experimental data fitted well with the pseudo-second-order model. Moreover, it suggests that the Langmuir isotherm is more adequate than the Freundlich isotherm in simulating the adsorption isotherm of As(V). The adsorption rate constant is 44.84 L mg(-1) and the maximum adsorption capacity is 0.39 mg g(-1). These findings indicate that the adsorption property of IOCP gives the compound a great potential for applications in environmental remediation. PMID:21282000

  19. Bimetallic oxamato complexes synthesized into mesoporous matrix as precursor to tunable nanosized oxide

    SciTech Connect

    Kalinke, Lucas H.G.; Stumpf, Humberto O.; Mazali, Italo O.; Cangussu, Danielle

    2015-10-15

    Highlights: • The bimetallic oxamato complexes as single-source precursor. • We prepared into a porous silica glass tunable nanosized oxide powders. • X-ray diffraction shows the formation of CeO{sub 2}/CuO and spinel cobaltite. • The different number of IDC allows control of the nanoparticle size. - Abstract: The bimetallic complexes were employed to prepare into a porous silica glass tunable nanosized oxide powders through the single source precursor (SSP) method. These materials were prepared by first anchoring of [Cu(opba)]{sup 2−} [opba = ortho-phenylenebis(oxamato)], second by reaction in situ with second metal [Co(II) or Ce(III)] and followed by a thermal treatment. The different number of impregnation–decomposition cycles (IDC) allows control of the nanoparticle size. X-ray diffraction shows the formation of mixture CeO{sub 2}–CuO and spinel copper cobaltite. Raman spectroscopy confirmed the formation of such phases. Transmission electron microscopy images revealed that spinel cobaltite particles (8 IDC) present a mean size of about 9 nm, whereas for the CeO{sub 2}–CuO phase the particle diameters are 4 nm (2 IDC) and 8 nm (6 IDC). For CeO{sub 2}–CuO the diffuse reflectance spectroscopy indicates a consistent red shift in band gap from 3.41 to 2.87 eV with increasing of particle size due to quantum confinement effect.

  20. Study of sodium hyaluronate-based intranasal formulations containing micro- or nanosized meloxicam particles.

    PubMed

    Bartos, Csilla; Ambrus, Rita; Sipos, Péter; Budai-Szűcs, Mária; Csányi, Erzsébet; Gáspár, Róbert; Márki, Árpád; Seres, Adrienn B; Sztojkov-Ivanov, Anita; Horváth, Tamás; Szabó-Révész, Piroska

    2015-08-01

    This article reports on the micro- and nanonization of meloxicam (MEL) with the aim of developing pre-dispersions as intermediates for the design of intranasal formulations. As a new approach, combined wet milling technology was developed in order to reduce the particle size of the MEL. Different milling times resulted in micro- or nanosized MEL in the pre-dispersions with polyvinyl alcohol as stabilizer agent, which were directly used for preparing intranasal liquid formulations with the addition of sodium hyaluronate as mucoadhesive agent. Reduction of the MEL particle size into the nano range led to increased saturation solubility and dissolution velocities, and increased adhesiveness to surfaces as compared with microsized MEL particles. A linear correlation was demonstrated between the specific surface area of MEL and the AUC. The in vitro and in vivo studies indicated that the longer residence time and the uniform distribution of nano MEL spray throughout an artificial membrane and the nasal mucosa resulted in better diffusion and a higher AUC. Nanosized MEL may be suggested for the development of an innovative dosage form with a different dose of the drug, as a possible administration route for pain management. PMID:26142244

  1. Development of High Performance Magnesium Matrix Nanocomposites Using Nano-SiC Particulates as Reinforcement

    NASA Astrophysics Data System (ADS)

    Shen, M. J.; Ying, W. F.; Wang, X. J.; Zhang, M. F.; Wu, K.

    2015-10-01

    In the present study, magnesium-based composites with three different volume percentages of nano-sized SiC particulates (SiCp) reinforcement were fabricated using a simple and inexpensive technique followed by hot extrusion. Microstructural characterization of the materials revealed uniform distribution of nano-size SiCp and obvious grain refinement. The tensile test result indicates a remarkable improvement on the strength for the as-extruded SiCp/AZ31B nanocomposite, while the elongation to fracture was decreased by comparing with the AZ31B alloy. Although, compared with the as-extruded AZ31B alloy, the ductility of the SiCp-reinforced AZ31B nanocomposite is decreased, but the ductility of the present SiCp-reinforced AZ31B nanocomposite is far higher than that of the conventional micron or submicron SiCp-reinforced magnesium matrix composites. It is concluded that, compared with the larger sized (micron or submicron) particles, the addition of nano SiCp in the AZ31B alloy resulted in the best combination of the strength and ductility. An attempt is made in the present study to correlate the effect of presence of nano-SiCp as reinforcement and its increasing amount with the microstructural and mechanical properties of magnesium.

  2. Snow-borne nanosized particles: Abundance, distribution, composition, and significance in ice nucleation processes

    NASA Astrophysics Data System (ADS)

    Rangel-Alvarado, Rodrigo Benjamin; Nazarenko, Yevgen; Ariya, Parisa A.

    2015-11-01

    Physicochemical processes of nucleation constitute a major uncertainty in understanding aerosol-cloud interactions. To improve the knowledge of the ice nucleation process, we characterized physical, chemical, and biological properties of fresh snow using a suite of state-of-the-art techniques based on mass spectrometry, electron microscopy, chromatography, and optical particle sizing. Samples were collected at two North American Arctic sites, as part of international campaigns (2006 and 2009), and in the city of Montreal, Canada, over the last decade. Particle size distribution analyses, in the range of 3 nm to 10 µm, showed that nanosized particles are the most numerous (38-71%) in fresh snow, with a significant portion (11 to 19%) less than 100 nm in size. Particles with diameters less than 200 nm consistently exhibited relatively high ice-nucleating properties (on average ranged from -19.6 ± 2.4 to -8.1 ± 2.6°C). Chemical analysis of the nanosized fraction suggests that they contain bioorganic materials, such as amino acids, as well as inorganic compounds with similar characteristics to mineral dust. The implication of nanoparticle ubiquity and abundance in diverse snow ecosystems are discussed in the context of their importance in understanding atmospheric nucleation processes.

  3. Nano-sized Superlattice Clusters Created by Oxygen Ordering in Mechanically Alloyed Fe Alloys.

    PubMed

    Hu, Yong-Jie; Li, Jing; Darling, Kristopher A; Wang, William Y; VanLeeuwen, Brian K; Liu, Xuan L; Kecskes, Laszlo J; Dickey, Elizabeth C; Liu, Zi-Kui

    2015-01-01

    Creating and maintaining precipitates coherent with the host matrix, under service conditions is one of the most effective approaches for successful development of alloys for high temperature applications; prominent examples include Ni- and Co-based superalloys and Al alloys. While ferritic alloys are among the most important structural engineering alloys in our society, no reliable coherent precipitates stable at high temperatures have been found for these alloys. Here we report discovery of a new, nano-sized superlattice (NSS) phase in ball-milled Fe alloys, which maintains coherency with the BCC matrix up to at least 913 °C. Different from other precipitates in ferritic alloys, this NSS phase is created by oxygen-ordering in the BCC Fe matrix. It is proposed that this phase has a chemistry of Fe3O and a D03 crystal structure and becomes more stable with the addition of Zr. These nano-sized coherent precipitates effectively double the strength of the BCC matrix above that provided by grain size reduction alone. This discovery provides a new opportunity for developing high-strength ferritic alloys for high temperature applications. PMID:26134420

  4. Nano-sized Superlattice Clusters Created by Oxygen Ordering in Mechanically Alloyed Fe Alloys

    NASA Astrophysics Data System (ADS)

    Hu, Yong-Jie; Li, Jing; Darling, Kristopher A.; Wang, William Y.; Vanleeuwen, Brian K.; Liu, Xuan L.; Kecskes, Laszlo J.; Dickey, Elizabeth C.; Liu, Zi-Kui

    2015-07-01

    Creating and maintaining precipitates coherent with the host matrix, under service conditions is one of the most effective approaches for successful development of alloys for high temperature applications; prominent examples include Ni- and Co-based superalloys and Al alloys. While ferritic alloys are among the most important structural engineering alloys in our society, no reliable coherent precipitates stable at high temperatures have been found for these alloys. Here we report discovery of a new, nano-sized superlattice (NSS) phase in ball-milled Fe alloys, which maintains coherency with the BCC matrix up to at least 913 °C. Different from other precipitates in ferritic alloys, this NSS phase is created by oxygen-ordering in the BCC Fe matrix. It is proposed that this phase has a chemistry of Fe3O and a D03 crystal structure and becomes more stable with the addition of Zr. These nano-sized coherent precipitates effectively double the strength of the BCC matrix above that provided by grain size reduction alone. This discovery provides a new opportunity for developing high-strength ferritic alloys for high temperature applications.

  5. Nanosized sensor materials based on CeO2/SnO2-Sb2O5

    NASA Astrophysics Data System (ADS)

    Oleksenko, L. P.; Maksymovych, N. P.; Matushko, I. P.; Chubaevskaya, N. V.

    2015-03-01

    Semiconductor nanosized SnO2-Sb2O5 materials with additives of cerium are synthesized by solgel method and the sensitivity to hydrogen of adsorption-semiconductor sensors, created on their basis, was investigated. It is shown that introducing cerium into the gas-sensitive layer of a sensor increases its sensitivity to microconcentrations of H2.

  6. NANOSIZED MAGNESIUM OXIDE AS CATALYST FOR THE RAPID AND GREEN SYNTHESIS OF SUBSTITUTED 2-AMINO-2-CHROMENES

    EPA Science Inventory

    A nanosized magnesium oxide catalyzed three-component condensation reaction of aldehyde, malononitrile and ¿-naphthol proceeded rapidly in water/PEG to afford corresponding 2-amino-2-chromenes in high yields at room temperature. The greener protocol was found to be fairly general...

  7. Nanosized TiO[subscript 2] for Photocatalytic Water Splitting Studied by Oxygen Sensor and Data Logger

    ERIC Educational Resources Information Center

    Zhang, Ruinan; Liu, Song; Yuan, Hongyan; Xiao, Dan; Choi, Martin M. F.

    2012-01-01

    Photocatalytic water splitting by semiconductor photocatalysts has attracted considerable attention in the past few decades. In this experiment, nanosized titanium dioxide (nano-TiO[subscript 2]) particles are used to photocatalytically split water, which is then monitored by an oxygen sensor. Sacrificial reagents such as organics (EDTA) and metal…

  8. Partial oxidation (“aging”) and surface modification decrease the toxicity of nano-sized zero valent iron.

    EPA Science Inventory

    Nanosize zero-valent iron (nZVI) is used as a redox-active catalyst for in situ remediation of contaminated ground waters. In aqueous environments, nZVI oxidizes over time (i.e., “ages”) to magnetite and other oxides. For remediation, hi...

  9. Synthesis of nano-sized amorphous boron powders through active dilution self-propagating high-temperature synthesis method

    SciTech Connect

    Wang, Jilin; Gu, Yunle; Li, Zili; Wang, Weimin; Fu, Zhengyi

    2013-06-01

    Graphical abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed. Highlights: ► Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis method. ► The morphology, particle size and purity of the samples could be effectively controlled via changing the endothermic rate. ► The diluter KBH{sub 4} played an important role in active dilution synthesis of amorphous nano-sized boron powders. ► The active dilution method could be further popularized and become a common approach to prepare various inorganic materials. - Abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method at temperatures ranging from 700 °C to 850 °C in a SHS furnace using Mg, B{sub 2}O{sub 3} and KBH{sub 4} as raw materials. Samples were characterized by X-ray powder diffraction (XRD), Laser particle size analyzer, Fourier transform infrared spectra (FTIR), X-ray energy dispersive spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission TEM (HRTEM). The boron powders demonstrated an average particle size of 50 nm with a purity of 95.64 wt.%. The diluter KBH{sub 4} played an important role in the active dilution synthesis of amorphous nano-sized boron powders. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed.

  10. Modifying Effects of Nanosized Diamonds on Hydrolytic Potential of Macrophages In Vitro.

    PubMed

    Neshchadim, D V; Arkhipov, S A; Shkurupy, V A; Akhramenko, E S; Troitskii, A V; Karpov, M A

    2015-07-01

    The effects of nanosized particles (4-6 nm) of synthetic diamonds on mouse macrophage expression and secretion of lysosomal cathepsins (B and D) and MMP-1 and MMP-9 were studied in vitro. Culturing of peritoneal macrophages in medium with diamond nanoparticles led to an increase in the counts of macrophages expressing the above enzymes and to stimulation of their secretion. However, the manifestations of these effects varied significantly for various enzymes. The data indicate modulation of macrophage functions by nanodiamonds. These results help better understand the possible role of the "corpuscular" xenobiotic factors in the pathogenesis of diseases associated with macrophage capturing of these factors irrespective of their chemical "activity". PMID:26212815

  11. Characterization of nano-sized SiC@Ni composite fabricated by electroless plating method.

    PubMed

    Xu, Zhan; Chen, Yigang

    2013-02-01

    A nano-sized SiC@Ni composite was prepared by simple electroless plating method. Nickel can be reduced by Na2H2PO2 under the catalysis of Pd to despite onto the surface of SiC nanoparticles. The composite structure was characterized by means of TEM images, XRD and the components were analyzed using EDS. The coating layer on the SiC particles was several nanometers thick and mainly in a form of fine Ni crystalline grain and amorphous Ni-P alloy. By increasing the concentration of Na2H2PO2 in the plating bath, the uniformity of the coating layer can be improved obviously. Both of the magnetism and crystallinity of Ni coatings depends on the P content in the coating which can be decreased by increasing the pH values of plating solutions. The SiC@Ni particles exhibited soft magnetic characteristics. PMID:23646660

  12. Relationships between the structure and the surface activity of nano-sized alumina in acid catalysis

    SciTech Connect

    Coster, D.; Gruver, V.; Blumenfeld, A.; Fripiat, J.J.

    1994-12-31

    As shown in another communication to Symposium 5, nano-sized aluminas enriched in pentacoordinated aluminum (Al{sup V}) are obtained through the limited hydrolysis of aluminum alkoxides. Here the surface properties of these aluminas are investigated from the catalytic point of view. The goal is to obtain geometrical information on the Lewis acid sites. {sup 1}H{r_arrow}{sup 27}Al (cross-polarization) high resolution MAS NMR, using chemisorbed NH{sub 3} which acts as a {sup 1}H spin reservoir, allows the direct observation of surface Al involved in the catalytic site. The polarization transfer from these protons to surface Al is remarkably efficient because of the relatively short Al:N-H distance. It is observed that the main Lewis acid sites are located on distorted tetrahedral aluminum and pentacoordinated Al. These results are compared to low temperature infrared data of adsorbed CO.

  13. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-05-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  14. Nanoscaffold matrices for size-controlled, pulsatile transdermal testosterone delivery: nanosize effects on the time dimension

    NASA Astrophysics Data System (ADS)

    Malik, Ritu; Tondwal, Shailesh; Venkatesh, K. S.; Misra, Amit

    2008-10-01

    Pulsatile transdermal testosterone (T) has applications in hormone supplementation and male contraception. Pulsatile T delivery was achieved by assembling crystalline and nanoparticulate T in nucleation-inhibiting polymer matrices of controlled porosity. Different interference patterns observed from various polymeric films containing T were due to the various particle sizes of T present in the polymer matrices. Scanning electron microscopy was used to determine the size and shape of T crystals. Skin-adherent films containing T nanoparticles of any size between 10-500 nm could be prepared using pharmaceutically acceptable vinylic polymers. Drug release and skin permeation profiles were studied. The dissolution-diffusion behavior of nanoparticles differed from crystalline and molecular states. Nanosize may thus be used to engineer chronopharmacologically relevant drug delivery.

  15. Vortex Properties of Nanosized Superconducting Strips with One Central Weak Link Under an Applied Current Drive

    NASA Astrophysics Data System (ADS)

    Peng, Lin; Cai, Chuanbing

    2016-06-01

    The static and dynamic properties of vortices in a nanosized superconducting strip with one central weak link (weakly superconducting region or normal metal) are investigated in the presence of external magnetic and electric fields. The time-dependent Ginzburg-Landau equations are used to describe the electronic transport and have been solved numerically by a finite element analysis. Anisotropy is included through the spatially dependent anisotropy coefficient ζ in different layers of the sample. Our results show that the energy barrier for vortices to enter a weak link is smaller than that for vortices to enter the superconducting layers. The magnetization shows periodic oscillations. With the introduction of the weak link, the period of oscillations decreases.

  16. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  17. Degradation of dimethylformamide on the surface of the nanosized WO3 films studied by infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Gavrilyuk, A. I.

    2016-07-01

    Here I report on the degradation of dimethylformamide on the surface of the nanosized WO3 films under the action of light. Dimethylformamide, a substance that has a series of interesting properties, was adsorbed on the surface of the WO3 films and its adsorption mechanism and transformations under the action of light have been investigated with the help of the IR spectroscopy. The spirit of the research is that both DMF modifications have been used i.e., conventional and that with the substitution of hydrogen atoms by deuterium. Formation of two weak bonds (donor-acceptor bond and hydrogen bond) provides a great catalytic effect for photo-initiated proton-coupled electron transfer from the adsorbed molecules to the WO3 film surface. The mechanism of the detachment of hydrogen atoms and subsequent transformation of the adsorbed molecules has been investigated and discussed.

  18. Phonon properties of nanosized MnWO 4 with different size and morphology

    NASA Astrophysics Data System (ADS)

    Mączka, MirosŁaw; Ptak, Maciej; Kurnatowska, Michalina; Kępiński, Leszek; Tomaszewski, PaweŁ; Hanuza, Jerzy

    2011-09-01

    Highly hierarchical barlike and flowerlike MnWO 4 microcrystals have been synthesized for the first time by a hydrothermal method, where ethanolamine (EA) and cetyltrimethylamonnium bromide (CTAB) play important roles in directing growth and self-assembly of these structures. The possible formation process has been proposed. In addition, platelike nanosized MnWO 4 was also synthesized by annealing of a precursor obtained by coprecipitation method. The obtained samples were characterized by XRD, SEM, TEM, Raman and IR methods. Raman spectra showed relatively weak dependence on particle size and morphology of the particles. In contrast to this behavior, IR-active bands showed pronounced shifts and changes in relative intensities on particle size and the morphology. Origin of this behavior is discussed.

  19. Nanosized graphene sheets enhanced photoelectric behavior of carbon film on p-silicon substrate

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Hu, Gaijuan; Zhang, Dongqing; Diao, Dongfeng

    2016-07-01

    We found that nanosized graphene sheets enhanced the photoelectric behavior of graphene sheets embedded carbon (GSEC) film on p-silicon substrate, which was deposited under low energy electron irradiation in electron cyclotron resonance plasma. The GSEC/p-Si photodiode exhibited good photoelectric performance with photoresponsivity of 206 mA/W, rise and fall time of 2.2, and 4.3 μs for near-infrared (850 nm) light. The origin of the strong photoelectric behavior of GSEC film was ascribed to the appearance of graphene nanosheets, which led to higher barrier height and photoexcited electron-collection efficiency. This finding indicates that GSEC film has the potential for photoelectric applications.

  20. Nano-sized Lithium Manganese Oxide Dispersed on Carbon Nanotubes for Energy Storage Applications

    SciTech Connect

    Bak, S.B.

    2009-08-01

    Nano-sized lithium manganese oxide (LMO) dispersed on carbon nanotubes (CNT) has been synthesized successfully via a microwave-assisted hydrothermal reaction at 200 C for 30 min using MnO{sub 2}-coated CNT and an aqueous LiOH solution. The initial specific capacity is 99.4 mAh/g at a 1.6 C-rate, and is maintained at 99.1 mAh/g even at a 16 C-rate. The initial specific capacity is also maintained up to the 50th cycle to give 97% capacity retention. The LMO/CNT nanocomposite shows excellent power performance and good structural reversibility as an electrode material in energy storage systems, such as lithium-ion batteries and electrochemical capacitors. This synthetic strategy opens a new avenue for the effective and facile synthesis of lithium transition metal oxide/CNT nanocomposite.

  1. Synthesis and photocatalytic applications of nano-sized zinc-doped mesoporous titanium oxide

    SciTech Connect

    Sánchez-Muñoz, Sergio; Pérez-Quintanilla, Damián

    2013-02-15

    Graphical abstract: Nano-sized mesoporous titanium oxide (T0) and zinc-doped nano-sized mesoporous titanium oxides (TA–TD) were synthesized by a simple method and characterized by different techniques. All materials have been studied in the photocatalytic degradation of methylene blue under UV light, observing that the decrease in the band gap of the materials seems to have a positive influence in the photocatalytic activity. Display Omitted Highlights: ► Nano-sized mesoporous TiO{sub 2} and Zn-doped TiO{sub 2} have been synthesized and characterized. ► Band gap of the Zn-doped TiO{sub 2} decreases when the Zn amount increases. ► Materials consist of porous particles (10–20 nm). ► The photocatalytic degradation of MB has been studied for these materials. ► A decrease in the band gap of the materials enhances the photocatalytic activity. -- Abstract: The synthesis of nano-sized mesoporous titanium oxide (T0) is described by an easy synthetic method which consists of the reaction of titanium tetraisopropoxide and a solution of HNO{sub 3} in water (pH 2.0) and the subsequent elimination of the volatiles by simple distillation. On the other hand, zinc-doped mesoporous titanium oxides (TA–TD) were synthesized using the same method but adding increasing amounts of Zn(NO{sub 3}){sub 2} to give materials which contain between 0.12 and 6.17 wt.% Zn. Upon the calcinations of all the obtained materials, characterization has been carried out by using N{sub 2} adsorption–desorption isotherms, powder X-ray diffraction, X-ray fluorescence, UV–vis spectrometry, solid state {sup 47,49}Ti NMR spectroscopy and transmission electronic microscopy (TEM). The results show that all these materials are mesoporous, with BET surfaces between 54 and 121 m{sup 2}/g and similar pore diameters between 6.4 and 9.1 nm. XRD studies show that these materials mainly consist of anatase and very small amounts of brookite. TEM technique shows the small particle sizes of the

  2. Dry-gel synthesis of shaped binderless zeolites composed of nanosized ZSM-5

    NASA Astrophysics Data System (ADS)

    Yue, Ming Bo; Yang, Na; Jiao, Wen Qian; Wang, Yi Meng; He, Ming-Yuan

    2013-06-01

    Shaped binderless ZSM-5 zeolites are prepared via a dry-gel conversion (DGC) technique from aluminosilicate extrudates, where the addition of seed gels not only provides crystal nuclei for rapid crystallization of zeolite but also controls the size of ZSM-5 crystal. Furthermore, the introduction of amine into the steam favors the formation of nanosized ZSM-5 zeolite. Especially, the morphology of these aluminosilicate extrudates well kept in the crystallization process. The obtained shaped zeolites are characterized by X-ray diffraction (XRD), nitrogen adsorption analysis, and scanning electron micrographs (SEM). The shaped zeolites show hierarchical structure with high mesopore volume (0.22 cm3 g-1) and demonstrate similar activity as commercial ZSM-5 samples in the transformation of i-propanol to hydrocarbons reaction.

  3. Explosive crystallization in the course of formation of Se/Ag nanosize film structure

    NASA Astrophysics Data System (ADS)

    Kogai, V. Ya.

    2014-08-01

    Results of an experimental study of explosive crystallization appearing in the process of formation of a Se/Ag nanosize film structure are presented. It is shown that explosive crystallization appears in a wide range of Se film thicknesses (70-280 nm) and occurs during a narrow time interval (2.00-4.52 s). The cooperative effect of the thermal energy of the phase transformation of Ag2Se and the energy of elastic stress in the amorphous Se film leads to development of an explosive crystallization. It was found that, depending on the relative thicknesses of Se and Ag films, orthorhombic Ag2Se with crystal-lattice constants a = 4.333 Å, b = 7.062 Å, and c = 7.764 Å and hexagonal Se ( a = 4.3552 Å and c = 4.9495 Å) are formed in the reaction products upon the explosive crystallization.

  4. Stimulated Brillouin scattering of laser in semiconductor plasma embedded with nano-sized grains

    SciTech Connect

    Sharma, Giriraj; Dad, R. C.; Ghosh, S.

    2015-07-31

    A high power laser propagating through semiconductor plasma undergoes Stimulated Brillouin scattering (SBS) from the electrostrictively generated acoustic perturbations. We have considered that nano-sized grains (NSGs) ions are embedded in semiconductor plasma by means of ion implantation. The NSGs are bombarded by the surrounding plasma particles and collect electrons. By considering a negative charge on the NSGs, we present an analytically study on the effects of NSGs on threshold field for the onset of SBS and Brillouin gain of generated Brillouin scattered mode. It is found that as the charge on the NSGs builds up, the Brillouin gain is significantly raised and the threshold pump field for the onset of SBS process is lowered.

  5. Large-scale and Rapid Synthesis of Disk-Shaped and Nano-Sized Graphene

    PubMed Central

    He, Chunyong; Jiang, San Ping; Shen, Pei Kang

    2013-01-01

    We synthesized disk-shaped and nano-sized graphene (DSNG) though a novel ion-exchange methodology. This new methodology is achieved by constructing metal ion/ion-exchange resin framework. The morphology and size of the graphene can be modulated by changing the mass ratio of the carbon-containing resin to the cobalt-containing precursor. This is the first time to show that the DSNG formed on the granular transition metal substrate. The DSNG gives a high intensity of photoluminescence at near-UV wavelength of 311 nm which may provide a new type of fluorescence for applications in laser devices, ultraviolet detector UV-shielding agent and energy technology. The emission intensity of the DSNG is thirty times higher than that of the commercial large graphene. Our approach for graphene growth is conveniently controllable, easy to scale-up and the DSNG shows superior luminescent properties as compared to conventional large graphene. PMID:23828273

  6. Pulsed laser-induced micro-and nanosized morphology and composition of titanium dental implants

    NASA Astrophysics Data System (ADS)

    Joób-Fancsaly, Á.; Divinyi, T.; Fazekas, Á.; Daroczi, Cs; Karacs, A.; Petõ, G.

    2002-10-01

    The surface morphology of machined screw-shaped titanium dental implants was modified by pulsed irradiation with an Nd glass laser. This method supplied very different surface elements in nanometer and micrometer ranges identified with scanning electron microscopy and atomic force microscopy as well. The surface composition was unchanged during these treatments. A rabbit experiment was carried out to investigate the direct bone contact (osseointegration) which was characterized by the removal torque of the implants. The 50 nm and 10-50 µm sized droplike elements were formed from the machined flat surface by the laser irradiation depending on the laser intensity. The osseointegration was enhanced by the increase of the density of nanosized elements and by the size of the microsized elements, showing the importance of this surface morphology in the direct bone-implant contact.

  7. Oxidative stress, cytoxicity, and cell mortality induced by nano-sized lead in aqueous suspensions.

    PubMed

    Cornejo-Garrido, Hilda; Kibanova, Daria; Nieto-Camacho, Antonio; Guzmán, José; Ramírez-Apan, Teresa; Fernández-Lomelín, Pilar; Garduño, Maria Laura; Cervini-Silva, Javiera

    2011-09-01

    This paper reports on the effect of aqueous and nano-particulated Pb on oxidative stress (lipid peroxidation), cytoxicity, and cell mortality. As determined by the Thiobarbituric Acid Reactive Substances (TBARS) method, only 6h after incubation aqueous suspensions bearing nano-sized PbO(2), soluble Pb(II), and brain-homogenate only suspensions, were determined to contain as much as ca. 7, 5, and 1 nmol TBARS mg protein(-1), respectively. Exposure of human cells (central nervous system, prostate, leukemia, colon, breast, lung cells) to nano-PbO(2) led to cell-growth inhibition values (%) ca. ≤18.7%. Finally, as estimated by the Artemia salina test, cell mortality values were found to show high-survival larvae rates. Microscopic observations revealed that Pb particles were swallowed, but caused no mortality, however. PMID:21640370

  8. Surface characteristics and photoactivity of silver-modified palygorskite clays coated with nanosized titanium dioxide particles

    SciTech Connect

    Zhao Difang . E-mail: zdf6910@163.com; Zhou Jie; Liu Ning

    2007-03-15

    This paper presents the results of a study in which nanosized titanium dioxide (TiO{sub 2}) crystal particles were coated onto the surface of palygorskite fibrous clay which had been modified by silver ions using titanium tetrachloride as a precursor. Coated TiO{sub 2} particles with the anatase structure were formed after calcining at 400 deg. C for 2 h in air. Various analytical techniques were used to characterize the surface properties of titanium dioxide particles on the palygorskite. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses showed that TiO{sub 2} particles were supported on the surface of the palygorskite clays and their size was in the range of 3-6 nm. The titanium oxide coatings were found to be very active for the photocatalytic decomposition of methylene blue.

  9. Hydrophilic and hydrophobic nano-sized Mn{sub 3}O{sub 4} particles

    SciTech Connect

    Gibot, Pierre Laffont, Lydia

    2007-02-15

    Mn{sub 3}O{sub 4} Hausmanite nanoparticles were prepared in aqueous solution by using metallic salt and hydrazine as precursor and reducing agent, respectively. The crystallite sizes ranged from 10 to 20 nm and the particle diameter distribution was very narrow and estimated between 20 and 30 nm. Influence of some parameters such as temperature, time of reaction, surfactant nature was studied for a synthesis in an aqueous medium. The as-made manganese oxides particles could be dispersed in an organic solvent containing stabilizing agents, according to perform the synthesis in an H{sub 2}O/n-hexan two-phase medium. These nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopies and nitrogen absorption measurements. - Graphical abstract: Hydrophobic nano-sized Mn{sub 3}O{sub 4} particles.

  10. Photoluminescence of nanosized Zn2SiO4:Mn depending upon preparation method

    NASA Astrophysics Data System (ADS)

    Petrovykh, K. A.; Kortov, V. S.; Rempel, A. A.

    2014-11-01

    Nanosized Zn2SiO4:Mn powders were prepared by two different methods: a high- energy ball-milling of microcrystalline powder (so-called "top-down") and a sol-gel method ("bottom-up"). It was shown that it is possible to obtain particles of 30±10 nm by means of the ball-milling. A particle size of the Zn2SiO4:Mn synthesized by the sol-gel method ranged from 20 to 110 nm. It was found all samples exhibit photoluminescence (PL) in the green spectral region with a maximum emission wavelength from 515 to 520 nm. A nanopowder obtained by the ball-milling showed a significant decrease of the PL intensity comparing with bulk material. The PL intensity of the samples prepared by sol-gel method is much higher than that of ball-milled Zn2SiO4:Mn.

  11. A study of nanosized magnesium ferrite particles with high magnetic moment

    NASA Astrophysics Data System (ADS)

    Sumangala, T. P.; Mahender, C.; Venkataramani, N.; Prasad, Shiva

    2015-05-01

    Nano-sized magnesium ferrite particles were prepared by sol gel combustion synthesis and were either furnace cooled or quenched after calcining at various temperatures ranging from 300 to 800 °C. A magnetisation value of 61 emu/g was obtained at 5 K for sample calcined at 800 °C and quenched in liquid nitrogen temperature. This is one of the highest reported values of magnetisation obtained from quenching at such a lower temperature. An estimate of the number of Fe3+ ions on A and B sites was made after applying Néel Model on the magnetisation values measured at 5 K. It was estimated that Fe3+ ions segregates out from both sites disproportionately so as to cause a net decrease in the overall moment. The resultant cation distribution is found to be consistent with the coercivity data.

  12. TiO2 nanosized powders controlling by ultrasound sol-gel reaction.

    PubMed

    Latt, Kyaing Kyaing; Kobayashi, Takaomi

    2008-04-01

    We studied that anatase-TiO2 powders prepared from sol-gel process of titanium tetra-isopropoxide (TTIP) were developed under ultrasonic irradiation with different frequency of 28, 45 and 100 kHz. The irradiated ultrasound (US) was controlled by using semi-cylindrical reflection plate that was placed onto the vicinity of reaction vessel. The focused US influenced the reduction of particles size and increased the surface area of resultant nanosized TiO2 powders. We also examined photodegradation of rhodamine 640 dye (Rh-640) solution by the resultant TiO2 under UV light exposure. It was observed that low frequency for TiO2 photocatalyst preparation and low calcination temperature were more affected onto the photodegradation of the dye. PMID:17904404

  13. Ferromagnetic resonance of micro- and nano-sized hexagonal ferrite powders at millimeter waves

    NASA Astrophysics Data System (ADS)

    Korolev, Konstantin A.; McCloy, John S.; Afsar, Mohammed N.

    2012-04-01

    Complex magnetic permeability and dielectric permittivity of micro- and nano-sized powdered barium (BaFe12O19) and strontium (SrFe12O19) hexaferrites have been studied in a broadband millimeter wave frequency range (30-120 GHz). Transmittance measurements have been performed using a free-space quasi-optical millimeter wave spectrometer, equipped with a set of high-power backward wave oscillators. Real and imaginary parts of dielectric permittivity for both types of micro- and nanoferrites have been calculated using analysis of recorded high-precision transmittance spectra. Frequency dependences of the magnetic permeability have been obtained from Schlömann's equation for partially magnetized ferrites. These materials show promise as tunable millimeter wave absorbers, based on their size-dependent absorption.

  14. Ferromagnetic Resonance of Micro- and Nano-sized Hexagonal Ferrite Powders at Millimeter Waves

    SciTech Connect

    Korolev, Konstantin A.; McCloy, John S.; Afsar, Mohammed N.

    2012-02-22

    Complex magnetic permeability and dielectric permittivity of micro- and nano-sized powdered barium (BaFe{sub 12}O{sub 19}) and strontium (SrFe{sub 12}O{sub 19}) hexaferrites have been studied in a broadband millimeter wave frequency range (30-120 GHz). Transmittance measurements have been performed using a free space quasi-optical millimeter wave spectrometer, equipped with a set of high power backward wave oscillators. Real and imaginary parts of dielectric permittivity for both types of micro- and nanoferrites have been calculated using analysis of recorded high precision transmittance spectra. Frequency dependences of the magnetic permeability have been obtained from Schloemann's equation for partially magnetized ferrites. These materials show promise as tunable millimeter wave absorber, based on their size-dependent absorption.

  15. Large-scale and Rapid Synthesis of Disk-Shaped and Nano-Sized Graphene

    NASA Astrophysics Data System (ADS)

    He, Chunyong; Jiang, San Ping; Shen, Pei Kang

    2013-07-01

    We synthesized disk-shaped and nano-sized graphene (DSNG) though a novel ion-exchange methodology. This new methodology is achieved by constructing metal ion/ion-exchange resin framework. The morphology and size of the graphene can be modulated by changing the mass ratio of the carbon-containing resin to the cobalt-containing precursor. This is the first time to show that the DSNG formed on the granular transition metal substrate. The DSNG gives a high intensity of photoluminescence at near-UV wavelength of 311 nm which may provide a new type of fluorescence for applications in laser devices, ultraviolet detector UV-shielding agent and energy technology. The emission intensity of the DSNG is thirty times higher than that of the commercial large graphene. Our approach for graphene growth is conveniently controllable, easy to scale-up and the DSNG shows superior luminescent properties as compared to conventional large graphene.

  16. Verwey transition of nano-sized magnetite crystals investigated by 57Fe NMR

    NASA Astrophysics Data System (ADS)

    Lim, Sumin; Choi, Baek Soon; Lee, Soon Chil; Hong, Jaeyoung; Lee, Jisoo; Hyeon, Taeghwan; Kim, Taehun; Jeong, Jaehong; Park, Je-Geun

    It is well known that magnetite crystals undergo a metal-insulator transition at the Verwey transition temperature, TV = 123 K. In this work, we studied the Verwey transition of nano-sized crystals with 57Fe NMR. In the metallic state above Tv, the NMR spectrum shows a single sharp peak, which broadens below TV indicating the Verwey transition. We measured the spectra of the nano-crystals with radii of 16 nm, 25 nm, and 40 nm and compared with that of a bulk. The transition temperature obtained from the NMR spectra depends on both the crystal size and crystallinity. When the crystal size decreases from bulk to 16 nm, the transition temperature drops from 123 K to 100 K. The transition temperature of the samples kept dry air decrease due to aging.

  17. Nanoporous Ge electrode as a template for nano-sized ( <5 nm) Au aggregates.

    PubMed

    Impellizzeri, Giuliana; Romano, Lucia; Fraboni, Beatrice; Scavetta, Erika; Ruffino, Francesco; Bongiorno, Corrado; Privitera, Vittorio; Grimaldi, Maria Grazia

    2012-10-01

    In this paper we present the extremely peculiar electrical properties of nanoporous Ge. A full and accurate electrical characterization showed an unexpected and extremely high concentration of positive carriers. Electrochemical analyses showed that nanoporous Ge has improved charge transfer properties with respect to bulk Ge. The electrode behavior, together with the large surface-to-volume ratio, make nanoporous Ge an efficient nanostructured template for the realization of other porous materials by electrodeposition. The pores were efficiently decorated by Au nanoparticles of diameter as low as 1-5 nm, prepared by electrochemical deposition. These new results demonstrate the potential and efficient use of nanoporous Ge as a nanostructured template for nano-sized Au aggregates, opening the way for the realization of innovative sensor devices. PMID:22972303

  18. Nanosized controlled surface pretreatment of biometallic alloy 316L stainless steel.

    PubMed

    Abdel-Fattah, Tarek M; Loftis, Derek; Mahapatro, Anil

    2011-12-01

    Stainless steel (AISI 316L) is a medical grade stainless steel alloy used extensively in medical devices and in the biomedical field. 316L stainless steel was successfully electropolished via an ecologically friendly and biocompatible ionic liquid (IL) medium based on Vitamin B4 (NB4) and resulting in nanosized surface roughness and topography. Voltammetry and chronoamperometry tests determined optimum polishing conditions for the stainless steel alloy while atomic force microscopy (AFM) and scanning electron microscopy (SEM) provided surface morphology comparisons to benchmark success of each electropolishing condition. Energy dispersive X-ray analysis (EDX) combined with SEM revealed significantly smoother surfaces for each alloy surface while indicating that the constituent metals comprising each alloy effectively electropolished at uniform rates. PMID:22416578

  19. Preparation of multiparticulate systems for oral delivery of a micronized or nanosized poorly soluble drug.

    PubMed

    Cerea, Matteo; Pattarino, Franco; Foglio Bonda, Andrea; Palugan, Luca; Segale, Lorena; Vecchio, Carlo

    2016-09-01

    The purpose of the present work was to prepare multiparticulate drug delivery systems for oral administration of a poorly soluble drug such as itraconazole. Multiparticulate systems were prepared by extrusion/spheronization technique using a mix of crospovidone, low viscosity hypromellose, microcrystalline cellulose, micronized drug and water. In order to improve the release performance of the multiparticulate systems, the micronized drug was suspended in water with polysorbate 20 and nanonized by a high-pressure homogenization. The suspension of drug nanoparticles was then spray-dried for enabling an easy handling of the drug and for preventing the over-wetting of the powders during extrusion/spheronization processing. Both multiparticulate units prepared with micronized or nanonized drug showed acceptable disintegrating properties. The nanosizing of micronized drug powder provided a significant improvement of drug dissolution rates of the multiparticulates. PMID:26786555

  20. Kinetic patterns in the formation of nanosized manganese-manganese oxide systems

    NASA Astrophysics Data System (ADS)

    Surovoi, E. P.; Bugerko, L. N.; Surovaya, V. E.; Zaikonnikova, T. M.

    2016-03-01

    Transformations in nanosized manganese films are studied by means of optical spectroscopy, microscopy, and gravimetry at different film thicknesses ( d = 4-108 nm) and temperatures of heat treatment ( T = 373-673 K). It is found that the kinetic curves of conversion are satisfactorily described in the terms of linear, inverse logarithmic, cubic, and logarithmic laws. The contact potential difference is measured for Mn and MnO films, and photo EMF is measured for Mn-MnO systems. An energy band diagram is constructed for Mn-MnO systems. A model for the thermal transformation of Mn films is proposed that includes stages of oxygen adsorption, the redistribution of charge carriers in the contact field of Mn-MnO, and manganese(II) oxide formation.

  1. Nature of Nano-Sized Plutonium Particles in Soils at the Hanford Site

    SciTech Connect

    Buck, Edgar C.; Moore, Dean A.; Czerwinski, Kenneth R.; Conradson, Steven D.; Batuk, Olga; Felmy, Andrew R.

    2014-08-06

    The occurrence of plutonium dioxide (PuO2) either from direct deposition or from the precipitation of plutonium-bearing solutions in contaminated soils and sediments has been well described, particularly for the Hanford site in Washington State. However, past research has suggested that plutonium may exist in environmental samples at the Hanford site in chemical forms in addition to large size PuO2 particles and that these previously unidentified nano-sized particles maybe more reactive and thus more likely to influence the environmental mobility of Pu. Here we present evidence for the formation of nano-sized plutonium iron phosphate hydroxide structurally related to the rhabdophane group nanoparticles in 216-Z9 crib sediments from Hanford using transmission electron microscopy (TEM). The distribution and nature of these nanoparticles varied depending on the adjacent phases present. Fine electron probes were used to obtain electron diffraction and electron energy-loss spectra from specific phase regions of the 216-Z9 cribs specimens from fine-grained plutonium oxide and phosphate phases. Energy-loss spectra were used to evaluate the plutonium N4,5 (4d → 5f ) and iron L2,3 absorption edges. The iron plutonium phosphate formation may depend on the local micro-environment in the sediments, availability of phosphate, and hence the distribution of these minerals may control long-term migration of Pu in the soil. This study also points to the utility of using electron beam methods for determining the identity of actinide phases and their association with other sediment phases.

  2. Fine cathode particles prepared by solid-state reaction method using nano-sized precursor particles

    NASA Astrophysics Data System (ADS)

    Ju, Seo Hee; Koo, Hye Young; Hong, Seung Kwon; Jo, Eun Byul; Kang, Yun Chan

    Fine-sized Li-Co-Mn-O cathode particles with various ratios of cobalt and manganese components were prepared by conventional solid-state reaction method using the nano-sized precursor particles. The nano-sized precursor particles of cobalt and manganese components were prepared by spray pyrolysis. The LiCo 1- xMn xO 2 (0.1 ≤ x ≤ 0.3) particles had finer size than that of the pure LiCoO 2 particles. Manganese component disturbed the growth of the LiCo 1- xMn xO 2 cathode particles prepared by solid-state reaction method. The initial discharge capacities of the layered LiCo 1- xMn xO 2 (0 ≤ x ≤ 0.3) cathode particles decreased from 144 to 136 mAh g -1 when the ratios of Co/Mn components were changed from 1/0 to 0.7/0.3. The mean sizes of the spinel LiMn 2- yCo yO 4 (0 ≤ y ≤ 0.2) cathode particles decreased from 650 to 460 nm when the ratios of Mn/Co components were changed from 2/0 to 1.8/0.2. The initial discharge capacities of the LiMn 2- yCo yO 4 (0 ≤ y ≤ 0.2) cathode particles decreased from 119 to 86 mAh g -1 when the ratios of Mn/Co components were changed from 2/0 to 1.8/0.2.

  3. Electronic and plasmonic properties of nano-sized gold/strontium titanate interface

    NASA Astrophysics Data System (ADS)

    Hou, Jiechang

    In this thesis, nano-sized metal/oxide interfaces are fabricated to determine the size dependence of electronic and resistive switching properties, effect of atomic structure on the orientation dependence of electronic properties, and mechanisms of plasmon-induced current enhancement. A combination of drop-casting and high temperature annealing enables orientation control over nano-sized metal/oxide interfaces. To examine the electronic properties, individual Au nanoparticle/SrTiO3 interfaces with sizes ranging from 20 to 150 nm are characterized via conductive atomic force microscopy, for two distinct interface orientations. Current-voltage characterization enables the determination of dominant electron transport mechanisms. The development of a depletion region results in the transition of electron transport mechanism from edge-effect-induced tunneling to inhomogeneity-induced statistical variations, as the interface decreases below a critical size. The resultant size-dependent Schottky properties dictate the size dependence of interface-controlled resistive switching behaviors, in addition to geometrical scaling of resistance. The effect of atomic structure on electronic properties is also investigated, via correlation of atomic structure characterized by high resolution transmission electron microscopy, electronic structure probed by electron energy loss spectroscopy, and measured electronic properties. The observed orientation dependence of reverse tunneling is attributed to interface defects induced by different atomic structures. Nanofabrication procedures are optimized to develop Au nano-antenna arrays on SrTiO3 substrate, to determine the photocurrent dependence on illumination condition and mechanisms of hot electron effect. Device design is assisted by finite-difference time-domain simulation of optical properties, targeted at near-infrared working range. Plasmon resonance frequency and intensity are demonstrated to be systematically tunable by varying

  4. Toughening of epoxies based on self-assembly of nano-sized amphiphilic block copolymer micelles

    NASA Astrophysics Data System (ADS)

    Liu, Jia

    As a part of a larger effort towards the fundamental understanding of mechanical behaviors of polymers toughened by nanoparticles, this dissertation focuses on the structure-property relationship of epoxies modified with nano-sized poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP-PEO) block copolymer (BCP) micelle particles. The amphiphilic BCP toughener was incorporated into a liquid epoxy resin and self-assembled into well-dispersed 15 nm spherical micelle particles. The nano-sized BCP, at 5 wt% loading, can significantly improve the fracture toughness of epoxy (ca. 180% improvement) without reducing modulus at room temperature and exhibits only a slight drop (ca. 5°C) in glass transition temperature (Tg). The toughening mechanisms were found to be BCP micelle nanoparticle cavitation, followed by matrix shear banding, which mainly accounted for the observed remarkable toughening effect. The unexpected "nano-cavitation" phenomenon cannot be predicted by existing physical models. The plausible causes for the observed nano-scale cavitation and other mechanical behaviors may include the unique structural characteristics of BCP micelles and the influence from the surrounding epoxy network, which is significantly modified by the epoxy-miscible PEO block. Other mechanisms, such as crack tip blunting, may also play a role in the toughening. Structure-property relationships of this nano-domain modified polymer are discussed. In addition, other important factors, such as strain rate dependence and matrix crosslink density effect on toughening, have been investigated. This BCP toughening approach and conventional rubber toughening techniques are compared. Insights on the decoupling of modulus, toughness, and Tg for designing high performance thermosetting materials with desirable physical and mechanical properties are discussed.

  5. Preparation of hemoglobin-loaded nano-sized particles with porous structure as oxygen carriers.

    PubMed

    Zhao, Jian; Liu, Chang-Sheng; Yuan, Yuan; Tao, Xin-Yi; Shan, Xiao-Qian; Sheng, Yan; Wu, Fan

    2007-03-01

    Hb (hemoglobin)-loaded particles (HbP) encapsulated by a biodegradable polymer used as oxygen carrier were prepared. A modified double emulsion and solvent diffusion/evaporation method was adopted. All experiments were performed based on two types of biodegradable polymers, poly(epsilon-caprolactone) (PCL) and poly(epsilon-caprolactone-ethylene glycol) (PCL-PEG). The biodistribution and the survival time in blood of the particles were investigated in a mouse model. Encapsulation efficiency and pore-connecting efficiency were evaluated by a novel sulfocyanate potassium method. The influence of process parameters on the particle size and pore-connecting efficiency (PCE%) of nanoparticles have been discussed. The prepared conditions: solvent, external aqueous phase, pressure were discussed. The system utilizing dichloromethane (DCM)/ethyl acetate (EA) as a solvent with an unsaturated external aqueous phase yielded the highest encapsulation efficiency (87.35%) with a small mean particle size (153 nm). The formation of porous channels was attributed to the diffusion of solvent. The PCE% was more sensitive to the rate of solvent diffusion that was obviously affected by the preparation temperature. The PCE% reached 87.47% when PCL-PEG was employed at 25 degrees C. P(50) of HbP was 27 mmHg, which does not seem to be greatly affected by the encapsulation procedure. In vivo, following intravenous injection of 6-coumarin labeled HbP, the major organ accumulating Hb-loaded particles was the liver. The half-life of nano-sized PCL HbP was 3.1 times as long as the micro-sized PCL HbP. Also, Nano-sized as well as a PEGylated surface on HbP is beneficial for prolonged blood residence (7.2 fold increase). PMID:17126898

  6. A New Nano-sized Iron Oxide Particle with High Sensitivity for Cellular Magnetic Resonance Imaging

    PubMed Central

    Chen, Chih-Lung; Zhang, Haosen; Ye, Qing; Hsieh, Wen-Yuan; Hitchens, T. Kevin; Shen, Hsin-Hsin; Liu, Li; Wu, Yi-Jen; Foley, Lesley M.; Wang, Shian-Jy; Ho, Chien

    2011-01-01

    Purpose In this study, we investigated the labeling efficiency and magnetic resonance imaging (MRI) signal sensitivity of a newly synthesized, nano-sized iron oxide particle (IOP) coated with polyethylene glycol (PEG), designed by Industrial Technology Research Institute (ITRI). Procedures Macrophages, bone-marrow-derived dendritic cells, and mesenchymal stem cells (MSCs) were isolated from rats and labeled by incubating with ITRI-IOP, along with three other iron oxide particles in different sizes and coatings as reference. These labeled cells were characterized with transmission electron microscopy (TEM), light and fluorescence microscopy, phantom MRI, and finally in vivo MRI and ex vivo magnetic resonance microscopy (MRM) of transplanted hearts in rats infused with labeled macrophages. Results The longitudinal (r1) and transverse (r2) relaxivities of ITRI-IOP are 22.71 and 319.2 s−1 mM−1, respectively. TEM and microscopic images indicate the uptake of multiple ITRI-IOP particles per cell for all cell types. ITRI-IOP provides sensitivity comparable or higher than the other three particles shown in phantom MRI. In vivo MRI and ex vivo MRM detect punctate spots of hypointensity in rejecting hearts, most likely caused by the accumulation of macrophages labeled by ITRI-IOP. Conclusion ITRI-IOP, the nano-sized iron oxide particle, shows high efficiency in cell labeling, including both phagocytic and non-phagocytic cells. Furthermore, it provides excellent sensitivity in T2*-weighted MRI, and thus can serve as a promising contrast agent for in vivo cellular MRI. PMID:20862612

  7. Nanosized carbon black combined with Ni2O3 as "universal" catalysts for synergistically catalyzing carbonization of polyolefin wastes to synthesize carbon nanotubes and application for supercapacitors.

    PubMed

    Wen, Xin; Chen, Xuecheng; Tian, Nana; Gong, Jiang; Liu, Jie; Rümmeli, Mark H; Chu, Paul K; Mijiwska, Ewa; Tang, Tao

    2014-04-01

    The catalytic carbonization of polyolefin materials to synthesize carbon nanotubes (CNTs) is a promising strategy for the processing and recycling of plastic wastes, but this approach is generally limited due to the selectivity of catalysts and the difficulties in separating the polyolefin mixture. In this study, the influence of nanosized carbon black (CB) and Ni2O3 as a novel combined catalyst system on catalyzing carbonization of polypropylene (PP), polyethylene (PE), polystyrene (PS) and their blends was investigated. We showed that this combination was efficient to promote the carbonization of these polymers to produce CNTs with high yields and of good quality. Catalytic pyrolysis and model carbonization experiments indicated that the carbonization mechanism was attributed to the synergistic effect of the combined catalysts rendered by CB and Ni2O3: CB catalyzed the degradation of PP, PE, and PS to selectively produce more aromatic compounds, which were subsequently dehydrogenated and reassembled into CNTs via the catalytic action of CB together with Ni particles. Moreover, the performance of the synthesized CNTs as the electrode of supercapacitor was investigated. The supercapacitor displayed a high specific capacitance as compared to supercapacitors using commercial CNTs and CB. This difference was attributed to the relatively larger specific surface areas of our synthetic CNTs and their more oxygen-containing groups. PMID:24611910

  8. Nanosized CuO and ZnO catalyst supported on titanium chip for conversion of carbon dioxide to methyl alcohol.

    PubMed

    Seo, Hyeong-Seok; Park, Chul-Min; Kim, Ki-Joong; Jeong, Woon-Jo; Chung, Min-Chul; Jung, Sang-Chul; Kim, Sang-Chai; Ahn, Ho-Geun

    2013-08-01

    In order to reutilize spent metallic titanium chips (TC) as catalyst support or photocatalytic materials, the surface of the TC was modified by thermal treatment under air atmosphere. TC-supported nanosized CuO and ZnO catalysts were prepared by impregnation (IMP) and co-precipitation (CP) method, respectively. The catalytic activity for CO2 hydrogenation to CH3OH was investigated using a flow-typed reactor under various reaction pressures. The crystals of CuO and ZnO was well formed on TC. CO2 conversion, CH3OH selectivity, and CH3OH yield were obtained as a function of time on stream over CuO-ZnO/TC catalysts. Conversion of CO2 to CH3OH over CuO-ZnO/TC catalyst by CP method and CuO/ZnO/TC catalyst by IMP method were ca. 16% and ca. 12%, respectively. Conversion of CO2 over CuO-ZnO/TC catalyst by CP method was increased with increasing reaction temperature in the range of 15-30 atm. Maximum selectivity and yield to CH3OH over CuO-ZnO/TC at 250 degrees C were ca. 90% at 20 atm and ca. 18.2% at 30 atm, respectively. PMID:23882842

  9. Catalytic Activity of Nanosized CuO-ZnO Supported on Titanium Chips in Hydrogenation of Carbon Dioxide to Methyl Alcohol.

    PubMed

    Ahn, Ho-Geun; Lee, Hwan-Gyu; Chung, Min-Chul; Park, Kwon-Pil; Kim, Ki-Joong; Kang, Byeong-Mo; Jeong, Woon-Jo; Jung, Sang-Chul; Lee, Do-Jin

    2016-02-01

    In this study, titanium chips (TC) generated from industrial facilities was utilized as TiO2 support for hydrogenation of carbon dioxide (CO2) to methyl alcohol (CH3OH) over Cu-based catalysts. Nano-sized CuO and ZnO catalysts were deposited on TiO2 support using a co-precipitation (CP) method (CuO-ZnO/TiO2), where the thermal treatment of TC and the particle size of TiC2 are optimized on CO2 conversion under different reaction temperature and contact time. Direct hydrogenation of CO2 to CH3OH over CuO-ZnO/TiO2 catalysts was achieved and the maximum selectivity (22%) and yield (18.2%) of CH3OH were obtained in the range of reaction temperature 210-240 degrees C under the 30 bar. The selectivity was readily increased by increasing the flow rate, which does not affect much to the CO2 conversion and CH3OH yield. PMID:27433722

  10. XAFS Study on Nano-Sized Pd Metal Catalyst Deposited on Ti-Containing Zeolite by a Photo-Assisted Deposition (PAD) Method

    SciTech Connect

    Yamashita, Hiromi; Miura, Yuki; Tomonari, Masanori; Masui, Yosuke; Mori, Kohsuke

    2007-02-02

    The nano-sized Pd metal catalyst can be highly deposited on Ti-containing silicalite zeolite (TS-1) under UV-light irradiation (PAD-Pd/TS-1) using a photo-assisted deposition (PAD) method. The nano-sized Pd metal was deposited having the direct interaction with the photo-excited tetrahedrally coordinated titanium oxide moieties of TS-1. Under a flow of H2 and O2 in water, H2O2 could be synthesized efficiently on this nano-sized Pd metal catalyst.

  11. The Effect of Nanosized Pb Liquid Phase on the Damping Behavior in Aluminum Matrix Composite Based on the 2024Al-BaPbO3 System

    NASA Astrophysics Data System (ADS)

    Fan, G. H.; Geng, L.; Wu, H.; Zheng, Z. Z.; Meng, Q. C.

    2016-03-01

    An aluminum matrix composite containing nanosized Pb particles was fabricated by a powder metallurgy technique based on the 2024Al-BaPbO3 system. The composite exhibited a high and broad damping peak at the melting temperature range of nanosized Pb particles. The increase in value and breadth of the damping peak was attributed to the dislocation damping of the interfacial matrix close to the nanosized Pb liquid phase. The damping peak is expected to be enhanced by further refining the Pb particle size.

  12. A nano-sized PARACEST-fluorescence imaging contrast agent facilitates & validates in vivo CEST MRI detection of glioma

    PubMed Central

    Ali, Meser M; Bhuiyan, Mohammed PI; Janic, Branislava; Varma, Nadimpalli RS; Mikkelsen, Tom; Ewing, James R; Knight, Robert A; Pagel, Mark D; Arbab, Ali S

    2012-01-01

    Aim The authors have investigated the usefulness of in vivo chemical exchange saturation transfer MRI for detecting gliomas using a dual-modality imaging contrast agent. Materials & methods A paramagnetic chemical exchange saturation transfer MRI contrast agent, Eu-1,4,7,10-tetraazacclododecane-1,4,7,10-tetraacetic acid-Gly4 and a fluorescent agent, DyLight® 680, were conjugated to a generation 5 polyamidoamine dendrimer to create the dual-modality, nano-sized imaging contrast agent. Results The agent was detected with in vivo chemical exchange saturation transfer MRI in an U87 glioma model. These results were validated using in vivo and ex vivo fluorescence imaging. Conclusion This study demonstrated the merits of using a nano-sized imaging contrast agent for detecting gliomas and using a dual-modality agent for detecting gliomas at different spatial scales. PMID:22891866

  13. Recent advances and future perspectives of nanosized zero- valent iron for extraction of heavy elements from metallurgical sludges

    NASA Astrophysics Data System (ADS)

    Mikhailov, I. Yu; Levina, V. V.; Kolesnikov, E. A.; Chuprunov, K. O.; Gusev, A. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    Advanced oxidation processes with nanosized zero-valent iron have presented great potential in wastewater treatment technology and now experience both increasing popularity and reliable technical improvements. Besides wastewater treatment, there is another promising application for an emerging technology of iron nanoparticles - as Fenton-like catalyst for extraction of valuable elements from poor and secondary raw materials such as metallurgical sludges. In present research, we carried out a set of experiments with emphasis on the physicochemical mechanisms and their relationship to the performance. In particular, we examined complex acidic - hydrogen peroxide leaching of zinc from blast furnace sludge with nanosized zero-valent iron as Fenton-like catalyst. Results of the experiments showed promising potential for subsequent application in extraction of heavy and rare-earth elements.

  14. Photodegradation of surfactants on the nanosized TiO2 prepared by hydrolysis of the alkoxide titanium.

    PubMed

    Zhang, Rubing; Gao, Lian; Zhang, Qinghong

    2004-01-01

    Nanosized TiO(2) was synthesized by hydrolysis of titanium tetraisopropoxide in the nanodroplets of microemulsions. The microemulsion provided by functionalized surfactants derived from the mixture of the commercially available sodium dodecylbenzensulfonate (DBS) and sodium dodecyl sulfate (DS). The resulting TiO(2) nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, and differential thermal analysis. Nanosized TiO(2) of anatase was found to show good photocatalytic properties in the photodegradation of DBS and DS surfactants. The cleavage of the aromatic moiety, the intermediate products and ultimate mineralization to CO(2) were examined in the process of photodegradation. A mechanism is also proposed on the basis of these experimental results. PMID:14575753

  15. Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

    SciTech Connect

    Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele; Antonio Pignedoli, Carlo; Patscheider, Joerg; Jeurgens, Lars P. H.; Antusek, Andrej; Parlinska-Wojtan, Magdalena; Bissig, Vinzenz

    2012-10-29

    Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

  16. Microemulsion synthesis of nanosized TiO(2) particles doping with rare-earth and their photocatalytic activity.

    PubMed

    Jian, Zicong; Pu, Yuying; Fang, Jianzhang; Ye, Zhiping

    2010-01-01

    Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO(2) and Ce-TiO(2) particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO(2) with doping TiO(2) , the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%. PMID:20630027

  17. Siderophores, the answer for micro to nanosized asbestos fibre related health hazard

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Shabori; Ledwani, Lalita; John, P. J.

    2016-04-01

    Recent studies on the potential toxicity of High Aspect Ratio Nanoparticles (HARN) has yet once again reinforced the health hazard imposed by asbestos fibres ranging from nano to micro size. Asbestos a naturally occurring fibrous mineral declared a Group I definite carcinogen by IARC (International Agency for Research on Cancer), a unit of WHO in the year 1987, has been extensively used since World War II to the near past for various commercial products. According to the most recent World Health Organization (WHO) estimates, asbestos-related diseases, resulting from exposure at workplace claims more than 107000 lives every year worldwide. The various types of toxic effects induced by asbestos in humans include - i) inflammation and fibrogenesis of lung, ii) mesothelioma iii) asbestosis and iv) bronchogenic carcinoma. The stability of asbestos in natural environment and its biological aggressiveness is related to their fibrous structure and dimensions. The actual risk associated with the exposure to nanosized asbestos, which is still unknown and escapes most regulations worldwide, has been shown in various toxicity assessment studies conducted on various animal models.In an effort to reduce the size of asbestos and therby its toxicity by limiting its biopersistence, oxalic acid treatment of asbestos coupled to power ultrasound treatment was carried out. The nanosized particles formed were still found to retain their hazardous effect. Similar were the results obtained on strong acid treatment of asbestos as well. A probable solution to the asbestos toxicity problem therefore envisaged was bioremediation. This involved the secretion of iron chelating molecules termed siderophores by microbes, which are of significance due to their ability to form very stable and soluble complexes with iron. Iron in asbestos composition is a major factor responsible for its carcinogenicity, removal or extraction of which would prove to be an effective answer to the worldwide problem

  18. Incorporation and measurement of synthetic nanosized iron oxides into soil profile for innovative agricultural applications

    NASA Astrophysics Data System (ADS)

    Guzmán, G.; Cañasveras, J. C.; Barrón, V.; Gómez, J. A.

    2012-04-01

    Iron oxides are natural constituents of soils providing them different characteristics. That differentiation has been used as in fingerprinting studies to determine sources of sediment, especially at large scales. However, there is a lack of studies that use this approach at smaller scales using iron oxides differences because these differences, among zones, are difficult to establish. The incorporation to soil profile of synthetic nanosized iron oxides could increase and improve the detection of differences in iron oxide properties among zones at plot or hillslope scales, solving problems that arise when that objective have been pursued with magnetic tracers of millimeter scale (Ventura et al. 2002). Magnetite (Fe3O4), hematite (α-Fe2O3) and goethite (FeOOH) can be commercially available as Bayferrox® 318M, 110 and 920 respectively, and traditionally used as pigments. Because of their properties, these iron oxides could fulfill all the requirements, defined by Zhang et al. 2001, for being sediment tracers. This communication describes the whole process of incorporation into the soil profile and the determination of the concentration of these iron oxides into the soil and in the transported sediment in water erosion experiments, and their use to estimate soil losses, identifying erosion and deposition areas, and quantifying the contribution to exported sediment of different zones. Their characteristics allowed a relatively easy detection by measuring the magnetic susceptibility, in the case of magnetite, and spectral properties by diffuse reflectance spectroscopy for hematite and goethite. Laboratory and field magnetic measurement techniques were set up considering bulk density variations at the soil samplings. Hematite and goethite measurements were also calibrated for the study-site soil and for different magnetite, hematite and goethite concentrations. A comparison of the measured iron oxide concentrations and a multivariate mixing model (Rhoton et al. 2008

  19. Ductility Enhancement of Molybdenum Phase by Nano-sized Oxide Dispersions

    SciTech Connect

    Kang, Bruce

    2008-07-18

    The objective of this research is to understand and to remedy the impurity effects for room-temperature ductility enhancement of molybdenum (Mo) based alloys by the inclusion of nano-sized metal oxide dispersions. This research combines theoretical, computational, and experimental efforts. The results will help to formulate systematic strategies in searching for better composed Mo-based alloys with optimal mechanical properties. For this project, majority of the research effort was directed to atomistic modeling to identify the mechanisms responsible for the oxygen embrittling and ductility enhancement based on fundamental electronic structure analysis. Through first principles molecular dynamics simulations, it was found that the embrittling impurity species were attracted to the metal oxide interface, consistent with previous experiments. Further investigation on the electronic structures reveals that the presence of embrittling species degrades the quality of the metallic chemical bonds in the hosting matrix in a number of ways, the latter providing the source of ductility. For example, the spatial flexibility of the bonds is reduced, and localization of the impurity states occurs to pin the dislocation flow. Rice’s criterion has been invoked to explain the connections of electronic structure and mechanical properties. It was also found that when impurity species become attracted to the metal oxide interface, some of the detrimental effects are alleviated, thus explaining the observed ductility enhancement effects. These understandings help to develop predictive capabilities to facilitate the design and optimization of Mo and other high temperature alloys (e.g. ODS alloys) for fossil energy materials applications. Based on the theoretical and computational studies, the experimental work includes the preparation of Mo powders mixed with candidate nano-sized metal oxides, which were then vacuum hot-pressed to make the Mo alloys. Several powder mixing methods

  20. Ecotoxicological studies of micro- and nanosized barium titanate on aquatic photosynthetic microorganisms.

    PubMed

    Polonini, Hudson C; Brandão, Humberto M; Raposo, Nádia R B; Mouton, Ludovic; Yéprémian, Claude; Couté, Alain; Brayner, Roberta

    2014-09-01

    The interaction between live organisms and micro- or nanosized materials has become a current focus in toxicology. As nanosized barium titanate has gained momentum lately in the medical field, the aims of the present work are: (i) to assess BT toxicity and its mechanisms on the aquatic environment, using two photosynthetic organisms (Anabaena flos-aquae, a colonial cyanobacteria, and Euglena gracilis, a flagellated euglenoid); (ii) to study and correlate the physicochemical properties of BT with its toxic profile; (iii) to compare the BT behavior (and Ba(2+) released ions) and the toxic profile in synthetic (Bold's Basal, BB, or Mineral Medium, MM) and natural culture media (Seine River Water, SRW); and (iv) to address whether size (micro, BT MP, or nano, BT NP) is an issue in BT particles toxicity. Responses such as growth inhibition, cell viability, superoxide dismutase (SOD) activity, adenosine-5-triphosphate (ATP) content and photosynthetic efficiency were evaluated. The main conclusions are: (i) BT have statistically significant toxic effects on E. gracilis growth and viability even in small concentrations (1μgmL(-1)), for both media and since the first 24 h; on the contrary of on A. flos-aquae, to whom the effects were noticeable only for the higher concentrations (after 96 h: ≥75 μg mL(-1) for BT NP and =100 μg mL(-1) for BT MP, in BB; and ≥75 μg mL(-1) for both materials in SRW), in spite of the viability being affected in all concentrations; (ii) the BT behaviors in synthetic and natural culture media were slightly different, being the toxic effects more pronounced when grown in SRW - in this case, a worse physiological state of the organisms in SRW can occur and account for the lower resistance, probably linked to a paucity of nutrients or even a synergistic effect with a contaminant from the river; and (iii) the effects seem to be mediated by induced stress without a direct contact in A. flos-aquae and by direct endocytosis in E. gracilis, but in

  1. Effects of Nano-sized Carbon Black on the Lungs of High Fat-diet Induced Overweight Rats

    PubMed Central

    Kang, Mingu; Han, Jeong-Hee; Yun, Hyo-In

    2013-01-01

    Objectives This study was conducted to determine whether nano-sized carbon black exposure results in greater damage in high fat diet-induced overweight rats than normal weight ones and to identify the possible causes of any differences. Methods Two groups of Sprague-Dawley rats allocated by body weight (normal and overweight) were exposed to aerosolized nano-sized carbon black for 6 hours a day, 5 days per week over a 4-week period. Differential cell counts, lactate dehydrogenase (LDH) activities and albumin concentrations were measured in bronchoalveolar lavage (BAL) fluid, and histopathological findings in the lungs were evaluated. Tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6 were measured in BAL fluid and supernatants of lipopolysaccharide(LPS)-stimulated lymphocyte culture. Results Rats exposed to high concentrations of nano-sized carbon black showed significantly increased (p<0.05) polymorphonuclear leukocyte number and LDH activity in the BAL fluid from both overweight and normal rats. Mild histopathological changes were observed in normal rats irrespective of carbon black concentrations. However, severe histological scores were found in overweight rats (1.75±0.46, 2.25±0.46, and 2.88±0.35 after low, medium, and high concentration exposures). Proinflammatory cytokine levels of TNF-α and IL-6 were significantly higher in the supernatant of LPS-stimulated lymphocytes of overweight rats, whereas there was no significant difference in the BAL fluid between normal and overweight rats. Conclusions Inflammation and damage to lungs exposed to nano-sized carbon black was more severe in high fat diet-induced overweight rats compared to normal rats. PMID:24303350

  2. Semiconductor adsorption sensors based on nanosized Pt/SnO2 materials and their sensitivity to methane

    NASA Astrophysics Data System (ADS)

    Fedorenko, G. V.; Oleksenko, L. P.; Maksymovych, N. P.; Matushko, I. P.

    2015-12-01

    The effect of platinum additives on the sensitivity of sensors based on nanosized tin oxide to methane is investigated. It is shown that addition of Pt increases a sensor's sensitivity to CH4. It is found that the dependences of electrical resistance and sensor sensitivity on the concentration of the impregnating solutions of H2[PtCl6] are extremal, which is explained from the point of view of heterogeneous catalysis concepts of the functioning of semiconductor adsorption sensors.

  3. Acute and reproductive toxicity of nano-sized metal oxides (ZnO and TiO₂) to earthworms (Eisenia fetida).

    PubMed

    Cañas, Jaclyn E; Qi, Beibei; Li, Shibin; Maul, Jonathan D; Cox, Stephen B; Das, Sriya; Green, Micah J

    2011-12-01

    An increase in nanomaterial applications will likely lead to an increased probability of environmental exposures, raising concerns regarding the safety of these materials. Recent studies have indicated that manufactured nanomaterials, such as metal oxides, have the potential to be harmful to aquatic and terrestrial organisms. The majority of nano-metal oxide research addressing potential toxicological issues has been focused in aquatic environments with very little terrestrial data. This study characterized the acute and reproductive toxicity of zinc oxide (ZnO) and titanium dioxide (TiO(2)) to earthworms (Eisenia fetida) in a terrestrial system. Following a 14 d exposure, nano-sized ZnO on filter paper was acutely toxic to E. fetida, while nano-sized TiO(2) did not exhibit acute toxicity. In contrast, neither nano-sized ZnO nor TiO(2) exhibited acute toxicity to earthworms in sand. Both nano-sized ZnO and TiO(2), following a 4 week exposure, caused reproductive effects in earthworms in artificial soil. Overall, nano-sized ZnO exhibited greater toxicity than nano-sized TiO(2) in Eisenia fetida. PMID:22020256

  4. Technological Aspects in Fabrication of Micro- and Nano-Sized Carbon Based Features: Nanorods, Periodical Arrays and Self-Standing Membranes

    NASA Astrophysics Data System (ADS)

    Ižák, Tibor; Domonkos, Mária; Babchenko, Oleg; Varga, Marián; Rezek, Bohuslav; Jurka, Vlastimil; Hruška, Karel; Kromka, Alexander

    2015-09-01

    Diamond and/or carbon thin films are in the center of interest due to their variability and extraordinary combination of intrinsic properties. However, some applications require fabrication of films with tailored properties. Especially, fabrication of periodic structures is highly attractive due to their increased surface area. In this contribution we point out the key technological aspects for fabrication of micro- and nano-sized carbon-based structures. Three representative structures are presented: diamond nanorods, self-assembled templates and self-standing diamond membranes. We found that the diameter of diamond nanorods can be controlled in a broad range from 10 to 200 nm by the masking material (Au vs Ni) and its initial thickness (from few to tens of nanometers). The assembly of polystyrene microspheres in mono- or multi-layer with square or hexagonal periodicities was controlled by the spin-coating parameters. The diamond porous membrane was selectively grown on Si substrate with an interdigital or mesh like geometry. Advantages of each structure as well as the fabrication limitations are discussed more in detail and finally their representative applications are pointed out.

  5. Effects of Nanosized Lithium Carbonate Particles on the Functional Activity of Macrophages During Development of Hepatocarcinoma 29.

    PubMed

    Konenkov, V I; Borodin, Yu I; Makarova, O P; Bgatova, N P; Rachkovskaya, L N

    2015-08-01

    The functional activity of macrophages in response to injection of nanosized lithium carbonate particles after initiation of hepatocarcinoma 29 in male CBA mice was evaluated by the production of NO, arginase activity, and absorption of zymosan granules. In intact animals, NO production by peritoneal macrophages increased by 4 times and arginase activity 3.1 times in response to a single injection of nanosized particles into the hip muscle. The level of NO production by macrophages remained high after 4 and 5 injections, while arginase activity returned to normal. The level of phagocytic peritoneal macrophages increased by 1.4 times after 5 injections of the particles. The level of NO production by macrophages gradually increased in animals with hepatocarcinoma developing in the hip muscle: by 1.6 times on day 3, 3.2 times on day 7, and by 2.6 times on day 13 in comparison with the corresponding parameters in intact animals. The increase of NO production by peritoneal macrophages after tumor process initiation was not paralleled by changes in arginase activity and absorption of zymosan granules. The results indicated that injection of nanosized lithium carbonate particles after inoculation of hepatocarcinoma 29 cells in the right hip muscle tissue was inessential for the function of peritoneal macrophages by the studied parameters. PMID:26388569

  6. Relationship between characteristic length and average grain size in nanosize MgO added Bi-2212 superconductor ceramics

    NASA Astrophysics Data System (ADS)

    Hamid, N. A.; Asbullah, M. S. N.; Yahya, S. Y. S.; Hashim, A.

    2012-09-01

    In the present work, Bi2Sr2CaCu2O8 (Bi-2212)/MgO compound was prepared using the conventional solid-state reaction method. The powder of nanosize MgO particles was added to Bi-2212 superconductor with weight percentage of 3%, 5%, and 8%, respectively. The compound was sintered for 48 hours at 855°C in air. Besides the existence of a small amount of impurity phases, all the samples showed the Bi-2212 phase as the dominant phase. The temperature dependence of transport current density (Jc) in zero magnetic fields for each sample was measured from 40 K to transition temperature (Tc). It was found that the Jc value decreased with increasing temperature and this showed the consequence of thermal activated flux creep. Using the self-field approximation together with Jc dependence on temperature, we estimated that the characteristic length (Lc) associated with the pinning force is approximately the same as the average grain size (Rg) for the non-added sample and for sample with 8% nanosize MgO addition. In contrast, for samples with 3% and 5% addition, the results showed that Lc < Rg. This indicates that addition of 3% to 5% of nanosize MgO particles provides the optimum flux pinning centers for Bi-2212 superconductor ceramics.

  7. The Effect of Crystallinity of Carbon Source on Mechanically Activated Carbothermic Synthesis of Nano-Sized SiC Powders

    NASA Astrophysics Data System (ADS)

    Moshtaghioun, B. M.; Monshi, A.; Abbasi, M. H.; Karimzadeh, F.

    2013-02-01

    The relevance of the structure of carbon materials and milling on the carbothermic reduction of silica to produce nano-sized silicon carbide (SiC) was studied. Graphite (crystalline) and metallurgical coke (mainly amorphous) were chosen as carbon precursors that were mixed with amorphous pure nano-sized SiO2 and milled for different times. The SiC yield at 1450 °C for l h was influenced by the degree of milling. Extending the milling time increased SiC formation in both cases. Although some extensive milling converted both sources of carbon into amorphous phase, the amount of synthesized SiC from graphite was about 4.5-3 times higher than coke with increased extent of milling. Graphite is converted from stable crystalline state into the amorphous phase, so it absorbs more activation energy of milling and fresher active centers are created, while the already amorphous coke absorbs less energy and thus less fresh active centers are created. This energy difference acts as a driving force, resulting in higher yield of nano-sized SiC when graphite is used as carbon source.

  8. Gold catalysts supported on nanosized iron oxide for low-temperature oxidation of carbon monoxide and formaldehyde

    NASA Astrophysics Data System (ADS)

    Tang, Zheng; Zhang, Weidong; Li, Yi; Huang, Zuming; Guo, Huishan; Wu, Feng; Li, Jinjun

    2016-02-01

    This study aimed to optimize synthesis of gold catalyst supported on nanosized iron oxide and to evaluate the activity in oxidation of carbon monoxide and formaldehyde. Nanosized iron oxide was prepared from a colloidal dispersion of hydrous iron oxide through a dispersion-precipitation method. Gold was adsorbed onto nanosized iron oxide under self-generated basic conditions. Characterization results indicate that the iron oxide consisted of hematite/maghemite composite with primary particle sizes of 6-8 nm. Gold was highly dispersed on the surface of the support. The catalysts showed good activity in the oxidation of airborne carbon monoxide and formaldehyde. The optimal pH for their synthesis was ∼7. The catalytic performance could be enhanced by extending the adsorption time of gold species on the support within 21 h. The optimized catalyst was capable of achieving complete oxidation of 1% carbon monoxide at -20 °C and 33% conversion of 450 ppm formaldehyde at ambient temperature. The catalyst may be applicable to indoor air purification.

  9. Synthesis of nanosized ZSM-5 zeolite using extracted silica from rice husk without adding any alumina source

    NASA Astrophysics Data System (ADS)

    Sari, Zahra Ghasemi Laleh Vajheh; Younesi, Habibollah; Kazemian, Hossein

    2015-08-01

    The synthesis of analcime and nanosized ZSM-5 zeolites was carried out by a hydrothermal method with silica extracted from rice husk, available as an inexpensive local biowaste, and without the use of an extra alumina source. Amorphous silica (with 88 wt% of SiO2) was extracted from rice husk ash by a suitable alkali solution. The effects of crystallization temperature, time and SiO2/Al2O3 ratio of the initial system on the properties of final products were investigated. For the characterization of the synthesized product, X-ray diffraction, scanning electron microscope, energy dispersive X-ray techniques, Fourier transform infrared and Brunauer-Emmett-Teller method were applied. Crystallinity percentages of analcime and nanosized ZSM-5 were 95.86 and 89.56, respectively, with specific surface area of 353.5 m2 g-1 for ZSM-5. The experimental results revealed that the synthesis of analcime and nanosized ZSM-5 zeolites was more practical with using silica extracted from inexpensive raw materials, while the whole crystallization process was accomplished without adding any alumina source during.

  10. Ultrasound-assisted synthesis of nanosized zero-valent iron for metal cations extraction and wastewater treatment applications

    NASA Astrophysics Data System (ADS)

    Mikhailov, I. Yu; Lysov, D. V.; Levina, V. V.; Mazov, I. N.; Gusev, A. A.; Yudintseva, T. I.; Kuznetsov, D. V.

    2016-01-01

    Nanosized zero-valent iron has shown good results in wastewater treatment and activation of physicochemical processes. Its applications in modern industry are complicated by high production costs of nanomaterials produced via existing synthesis routes. Therefore there is a need of cheap and high-productive methods of nanosized zero-valent iron with advanced functional properties. Improvement of oxidative conditions with additions may find its place in extraction of rare-earth metals, where high cost of nanomaterials could be viable. In this paper we studied an effect of ultrasonic irradiation on specific surface area and particle size of nanosized zero-valent iron synthesized by methods of chemical precipitation with high- temperature reduction in hydrogen flow and sodium borohydride reduction. Obtained results showed significant decrease of particle size and differences in particles morphology depending on presence of ultrasonication during synthesis and on chosen method. For ultrasonic-assisted synthesis with 100% amplitude, particle size calculated from specific surface area was 70 nm for sample synthesized by chemical precipitation with high-temperature reduction and 35 nm for borohydide reduction method compared to 63 nm for reference sample without ultrasonication.

  11. A facile preparation method of a PFC-containing nano-sized emulsion for theranostics of solid tumors.

    PubMed

    Shiraishi, Kouichi; Endoh, Reiko; Furuhata, Hiroshi; Nishihara, Masamichi; Suzuki, Ryo; Maruyama, Kazuo; Oda, Yusuke; Jo, Jun-ichiro; Tabata, Yasuhiko; Yamamoto, Jun; Yokoyama, Masayuki

    2011-12-15

    Theranostics means a therapy conducted in a diagnosis-guided manner. For theranostics of solid tumors by means of ultrasound, we designed a nano-sized emulsion containing perfluoropentane (PFC5). This emulsion can be delivered into tumor tissues through the tumor vasculatures owing to its nano-size, and the emulsion is transformed into a micron-sized bubble upon sonication through phase transition of PFC5. The micron-sized bubbles can more efficiently absorb ultrasonic energy for better diagnostic images and can exhibit more efficient ultrasound-driven therapeutic effects than nano-sized bubbles. For more efficient tumor delivery, smaller size is preferable, yet the preparation of a smaller emulsion is technically more difficult. In this paper, we used a bath-type sonicator to successfully obtain small PFC5-containing emulsions in a diameter of ca. 200nm. Additionally, we prepared these small emulsions at 40°C, which is above the boiling temperature of PFC5. Accordingly, we succeeded in obtaining very small nano-emulsions for theranostics through a very facile method. PMID:22023827

  12. Effect of solvents on the synthesis of nano-size zinc oxide and its properties

    SciTech Connect

    Kanade, K.G.; Kale, B.B. . E-mail: kbbb1@yahoo.com; Aiyer, R.C.; Das, B.K.

    2006-03-09

    The effect of the solvents on particle size and morphology of ZnO is investigated. The optical properties of nano ZnO were studied extensively. During this study, zinc oxalate was prepared in aqueous and organic solvents using zinc acetate and oxalic acid as precursors. The thermo-gravimetric analysis (TGA/DTA) showed formation of ZnO at 400 deg. C. Nano-size zinc oxide was obtained by thermal decomposition of aqueous and organic mediated zinc oxalate at 450 deg. C. The phase purity was confirmed by XRD and crystal size determined from transmission electron microscopy (TEM) was found to be 22-25 nm for the aqueous and 14 -17 nm in organic mediated ZnO. Scanning electron microscope (SEM) also revealed different nature of surfaces and microstructures for zinc oxide obtained in aqueous and organic solvents. The UV absorption spectra showed sharp absorption peaks with a blue shift for organic mediated ZnO, due to monodispersity and lower particle size. Sharp peaks and absence of any impurity peaks in photoluminescence spectra (PLS) complement the above observations.

  13. Bioinspired Design of an Immobilization Interface for Highly Stable, Recyclable Nanosized Catalysts.

    PubMed

    Kim, Insu; Son, Ho Yeon; Yang, Moon Young; Nam, Yoon Sung

    2015-07-01

    Immobilization of nanometer-sized metal catalysts into porous substrates can stabilize the catalysts and allow their recycled uses, while immobilization often sacrifices the active surface of catalysts and degenerates the local microenvironments, resulting in the reduction of the catalytic activity. To maintain a high activity of immobilized nanocatalysts, it is critically important to design an interface that minimizes the contact area and favors reaction chemistry. Here we report on the application of mussel-inspired adhesion chemistry to the formation of catalytic metal nanocrystal-polydopamine hybrid materials that exhibit a high catalytic efficiency during recycled uses. Electrospun polymer nanofibers are used as a template for in situ formation and immobilization of gold nanoparticles via polydopamine-induced reduction of ionic precursors. The prepared hybrid nanostructures exhibit a recyclable catalytic activity for the reduction of 4-nitrophenol with a turnover frequency of 3.2-5.1 μmol g(-1) min(-1). Repeated uses of the hybrid nanostructures do not significantly alter their morphology, indicating the excellent structural stability of the hybrid nanostructures. We expect that the polydopamine chemistry combined with the on-surface synthesis of catalytic nanocrystals is a promising route to the immobilization of various colloidal nanosized catalysts on supporting substrates for long-term catalysis without the physical instability problem. PMID:26076196

  14. Three-Dimensional Analysis of the Swimming Behavior of Daphnia magna Exposed to Nanosized Titanium Dioxide

    PubMed Central

    Noss, Christian; Dabrunz, André; Rosenfeldt, Ricki R.; Lorke, Andreas; Schulz, Ralf

    2013-01-01

    Due to their surface characteristics, nanosized titanium dioxide particles (nTiO2) tend to adhere to biological surfaces and we thus hypothesize that they may alter the swimming performance and behavior of motile aquatic organisms. However, no suitable approaches to address these impairments in swimming behavior as a result of nanoparticle exposure are available. Water fleas Daphnia magna exposed to 5 and 20 mg/L nTiO2 (61 nm; polydispersity index: 0.157 in 17.46 mg/L stock suspension) for 96 h showed a significantly (p<0.05) reduced growth rate compared to a 1-mg/L treatment and the control. Using three-dimensional video observations of swimming trajectories, we observed a treatment-dependent swarming of D. magna in the center of the test vessels during the initial phase of the exposure period. Ensemble mean swimming velocities increased with increasing body length of D. magna, but were significantly reduced in comparison to the control in all treatments after 96 h of exposure. Spectral analysis of swimming velocities revealed that high-frequency variance, which we consider as a measure of swimming activity, was significantly reduced in the 5- and 20-mg/L treatments. The results highlight the potential of detailed swimming analysis of D. magna for the evaluation of sub-lethal mechanical stress mechanisms resulting from biological surface coating and thus for evaluating the effects of nanoparticles in the aquatic environment. PMID:24260519

  15. Dextran based nanosized carrier for the controlled and targeted delivery of curcumin to liver cancer cells.

    PubMed

    Anirudhan, Thayyath Sreenivasan; Binusreejayan

    2016-07-01

    Curcumin (Cur), a poly phenolic yellow colored compound present in Indian spice turmeric, has a wide variety of biological properties. Bioavailability of Cur is limited by its low water solubility, rapid metabolism and low stability. In the present study, we mainly focus on synthesis and characterization of dextran based nano-sized drug carrier (GHDx) for the delivery of Cur. A liver targeting moiety is incorporated in GHDx so as to improve the therapeutic efficiency and decrease adverse effects of conventional cancer therapy. The effect of different parameters on grafting variables was studied. GHDx was characterised by FTIR, (1)H NMR XRD, TG/DTG, TEM, SEM, AFM, DLS and zeta potential analyses. Adsorption experiments were carried out for drug loading. Swelling of GHDx was studied as a function of pH and temperature. Three step release of Cur from GHDx was confirmed by analyzing in vitro release data in simulated intracellular pH using different kinetic models. In vitro cytotoxicity analysis on L929 and Hep G2 cells shows that GHDx is safe carrier while Cur loaded GHDx exhibits high toxicity with slow drug release towards hepatic cells. The results show that the GHDx can be customized as a stimuli sensitive potential carrier for the delivery of drugs. PMID:27012895

  16. Photocatalytic degradation of tetracycline in aqueous solution by nanosized TiO2.

    PubMed

    Zhu, Xiang-Dong; Wang, Yu-Jun; Sun, Rui-Juan; Zhou, Dong-Mei

    2013-08-01

    Tetracyclines are widely-used antibiotics in the world. Due to their poor absorption by human beings, or poultry and livestocks, most of them are excreted into the environment, causing growing concern about their potential impact, while photodegradation has been found to dominate their sequestration and bioavailability. Coupling with high-performance liquid chromatography-mass spectroscopy (HPLC-MS), gas chromatography-mass spectroscopy (GC-MS) and electron spin resonance (ESR), the mechanism of photocatalytic degradation of TC in aqueous solution by nanosized TiO2 (P25) under UV irradiation was investigated. The photocatalysis eliminated 95% of TC and 60% of total organic carbon (TOC) after 60 min irradiation, and NH4(+) ion was found to be one of the end-products. Bioluminescence assay showed that the toxicity of TC solution reached the maximum after 20 min irradiation and then gradually decreased. The degradation of TC included electron transfer, hydroxylation, open-ring reactions and cleavage of the central carbon. A possible photocatalytic degradation pathway of TC was proposed on the basis of the identified intermediates. Overall, the TiO2 photocatalysis was found to be a promising process for removing TC and its intermediates. PMID:23541148

  17. Nano-sized cobalt based Fischer-Tropsch catalysts for gas-to-liquid process applications.

    PubMed

    Kang, Jung Shik; Awate, S V; Lee, Yun Ju; Kim, So Jung; Park, Moon Ju; Lee, Sang Deuk; Hong, Suk-In; Moon, Dong Ju

    2010-05-01

    Nano-sized cobalt supported catalysts were prepared for Fischer-Tropsch synthesis in gas-to-liquid (GTL) process. The dependence of crystallite size and reducibility of Co3O4 on the supports were investigated with FTS activity. XRD peaks revealed nano crystallites (< 5.47 nm) of Co3O4 crystallites. TEM showed round shaped particles with size less than 5 nm. Support with higher acidity decreased crystallite size of Co3O4. XRD data of used catalysts showed Co3O4 crystallites smaller than 3.5 nm which do not reduce easily to Co(0) state. The crystallite size of Co3O4 plays a role in its reduction to Co(0). TPR results showed that the reduction temperature shifts to higher temperature due to metal-support interaction. The variation in the activity of the catalysts depends on the support which in turn affects the crystallite size, dispersion, reducibility and activity of Co species in Fischer-Tropsch Synthesis (FTS). In this study, Co/Al2O3 showed higher CO conversion than the other catalysts. However, the C5+ production was in order Co/SiO2 (78.1%) > Co/Al2O3 (70.0%) > Co/R_TiO2 (61%) > Co/A_TiO2 (57.5%). PMID:20359031

  18. Compound Method to Disperse CaCO3 Nanoparticles to Nano-Size in Water.

    PubMed

    Gu, Sui; Cai, Jihua; Wang, Jijun; Yuan, Ye; Chang, Dewu; Chikhotkin, Viktor F

    2015-12-01

    The invalidation of CaCO3 nanoparticles (nCaCO3) is often caused by the fact of agglomeration and inhomogeneous dispersion which limits its application into water-based drilling muds for low permeability reservoirs such as coalbed methane reservoir and shale gas/oil reservoir. Effective methods to disperse nCaCO3 to nano-size (≤ 100 nm) in water have seldom been reported. Here we developed a compound method containing mechanical stirring, ultrasonic treatment, the use of surfactant and stabilizer to disperse nCaCO3 in water. It comprises the steps adding 2% nCaCO3, 1% sodium dodecyl sulfonate (SDS), 2% cetyltrimethyl ammonium bromide (CTAB), 2% OP-10, 3% to 4% biopolymer (XC) in water successively, stirring it at a shear rate of 6000 to 8000 r/min for 15 minutes and treating it with ultrasonic at a frequency of 28 KHz for 30 to 40 minutes. The dispersed nCaCO3 was characterized with scanning electron microscope (SEM), transmission electron microscope (TEM) and particle size distribution (PSD) tests. We found that nCaCO3 could be dispersed to below 100 nm in water and the medium value of nCaCO3 was below 50 nm. This method paved the way for the utilization of nCaCO3 in drilling fluid and completion fluid for low permeability reservoirs such as coal seams and shale gas/oil formations. PMID:26682370

  19. Development of nano-sized hydroxyapatite reinforced composites for tissue engineering scaffolds.

    PubMed

    Huang, Jie; Lin, Yu Wan; Fu, Xiao Wei; Best, Serena M; Brooks, Roger A; Rushton, Neil; Bonfield, William

    2007-11-01

    Nano-sized hydroxyapatite (nanoHA) reinforced composites, mimicking natural bone, were produced. Examination by transmission electron microscopy revealed that the nanoHA particles had a rod-like morphology, 20-30 nm in width and 50-80 nm in length. The phase composition of hydroxyapatite was confirmed by X-ray diffraction. The nanoHA particles were incorporated into poly-2-hydroxyethylmethacrylate (PHEMA)/polycaprolactone (PCL) matrix to make new nanocomposites: nanoHA-PHEMA/PCL. Porous nanocomposite scaffolds were then produced using a porogen leaching method. The interconnectivity of the porous structure of the scaffolds was revealed by non-destructive X-ray microtomography. Porosity of 84% was achieved and pore sizes were approximately around 300-400 microm. An in vitro study found that the nanocomposites were bioactive as indicated by the formation of a bone-like apatite layer after immersion in simulated body fluid. Furthermore, the nanocomposites were able to support the growth and proliferation of primary human osteoblast (HOB) cells. HOB cells developed a well organized actin cytoskeletal protein on the nanocomposite surface. The results demonstrate the potential of the nanocomposite scaffolds for tissue engineering applications for bone repair. PMID:17891551

  20. SEM/AFM studies of cementitious binder modified by MWCNT and nano-sized Fe needles

    SciTech Connect

    Cwirzen, A.; Habermehl-Cwirzen, K.; Nasibulin, A.G.; Kaupinen, E.I.; Mudimela, P.R.; Penttala, V.

    2009-07-15

    Several compositions of cement paste samples containing multiwalled carbon nanotubes were produced using a small-size vacuum mixer. The mixes had water-to-binder ratios of 0.25 and 0.3. Sulfate resistant cement has been used. The multiwalled carbon nanotubes were introduced as a water suspension with added surfactant admixtures. The used surfactant acted as plasticizing agents for the cement paste and as dispersant for the multiwalled carbon nanotubes. A set of beams was produced to determine the compressive and flexural strengths. The scanning electron microscope and atomic force microscope studies of fractured and polished samples showed a good dispersion of multiwalled carbon nanotubes in the cement matrix. The studies revealed also sliding of multiwalled carbon nanotubes from the matrix in tension which indicates their weak bond with cement matrix. In addition to multiwalled carbon nanotubes also steel wires covered with ferrite needles were investigated to determine the bond strength between the matrix and the steel wire. These later samples consisted of 15-mm-high cylinders of cement paste with vertically cast-in steel wires. As reference, plain steel wires were cast, too. The bond strength between steel wires covered with nano-sized Fe needles appeared to be lower in comparison with the reference wires. The scanning electron microscope studies of fractured samples indicated on brittle nature of Fe needles resulting in shear-caused breakage of the bond to the matrix.

  1. Release and detection of nanosized copper from a commercial antifouling paint.

    PubMed

    Adeleye, Adeyemi S; Oranu, Ekene A; Tao, Mengya; Keller, Arturo A

    2016-10-01

    One major concern with the use of antifouling paints is the release of its biocides (mainly copper and zinc) into natural waters, where they may exhibit toxicity to non-target organisms. While many studies have quantified the release of biocides from antifouling paints, very little is known about the physicochemical state of released copper. For proper risk assessment of antifouling paints, characterization of copper released into water is necessary because the physicochemical state determines the metal's environmental fate and effects. In this study, we monitored release of different fractions of copper (dissolved, nano, and bulk) from a commercial copper-based antifouling paint. Release from painted wood and aluminum mini-bars that were submerged in natural waters was monitored for 180 days. Leachates contained both dissolved and particulate copper species. X-ray diffraction and X-ray photoelectron spectroscopy were used to determine the chemical phase of particles in the leachate. The amount of copper released was strongly dependent on water salinity, painted surface, and paint drying time. The presence of nanosized Cu2O particles was confirmed in paint and its leachate using single-particle inductively coupled plasma-mass spectrometry and electron microscopy. Toxicity of paint leachate to a marine phytoplankton was also evaluated. PMID:27393962

  2. Nanosized tungsten carbide synthesized by a novel route at low temperature for high performance electrocatalysis

    NASA Astrophysics Data System (ADS)

    Yan, Zaoxue; Cai, Mei; Shen, Pei Kang

    2013-04-01

    Tungsten carbide (WC) is a widely used engineering material which is usually prepared at high temperature. A new mechanism for synthesizing nanoscaled WC at ultralow temperature has been discovered. This discovery opens a novel route to synthesize valuable WC and other carbides at a cost-efficient way. The novel formation mechanism is based on an ion-exchange resin as carbon source to locally anchor the W and Fe species. As an intermediate, FeWO4 can be formed at lower temperature, which can be directly converted into WC along with the carbonization of resin. The size of WC can be less than 2 nm. The catalyst made with Pt nanoparticles supported on nanosized WC-GC (WC-graphitized carbon) shows enhanced electrocatalytic activity for oxygen reduction reaction. The result also indicates that the Pt nanoparticles deposited on WC-GC are dominated by Pt (111) plane and shows a mass activity of 257.7 mA mg-1Pt@0.9 V.

  3. Characterization of nano-sized iron particle layers spin coated on glass substrate

    NASA Astrophysics Data System (ADS)

    Dehipawala, Sunil; Samarasekara, Pubudu; Dahanayake, Rasika; Tremberger, George; Cheung, Tak D.; Gafney, Harry D.

    2015-08-01

    Nanometer scale iron particles have a variety of technological applications. They are vastly utilized in optical and microwave devices. Thin films with varying compositions of iron (III) nitrate and ethylene glycol were deposited on glass substrate using a spin coating technique. The thicknesses of the films were controlled by the spin rate. Precursor films on the substrate were then annealed to different temperatures ranging from 200°C to 600°C for 1-3 hours in air. The microstructures of iron particles in films prepared under different conditions were investigated using X-ray Absorption spectroscopy and Mossbauer spectroscopy. The main absorption edge peak position and pre-edge energy position were identical in samples with different numbers of layers, but prepared under similar conditions. This indicates that there was no change in the charge state of the iron regardless of the number of layers. However the intensity of the pre-edge feature decreases as the number of layers increases, which shows a decrease of Fe-O compounds as the number of layers increases. Mossbauer spectrum of these iron particles contains only quadrupole doublets. The absence of six-linespectrum confirms the nano-size nature of the particles.

  4. TiO2 nanosized powders by TiCl4 laser pyrolysis

    NASA Astrophysics Data System (ADS)

    Alexandrescu, R.; Dumitrache, F.; Morjan, I.; Sandu, I.; Savoiu, M.; Voicu, I.; Fleaca, C.; Piticescu, R.

    2004-05-01

    Nano-TiO2 powders were successfully prepared by laser pyrolysis of TiCl4 (vapours). Alternatively, air and nitrous oxide were used as oxygen precursors. C2H4 was used as an energy transfer agent. The underlying phenomena for this photon-based molecular nanotechnology are discussed. For the present report, different titania nanosized powder batches were obtained by variation of the oxidizer nature and TiCl4 precursor flows. X-ray diffraction, transmission electron microscopy, electron energy loss spectroscopy, x-ray dispersive energy analysis, and IR and Raman spectrometry have been used to analyse the nanostructures and morphologies of the as-synthesized powders. Medium and high resolution TEM analyses indicate mean grain sizes between 12 and 28 nm. The different characterization techniques suggest that in the obtained anatase and rutile mixture the fraction of rutile phase depends on the nature of the oxygen precursor. At low TiCl4 flows, no chlorine contamination was detected in the reaction product. Further examination of the influence of other important system parameters will open new possibilities for titania preparation by the laser pyrolysis of TiCl4.

  5. Preparation of designed poly(D,L-lactide)/nanosized hydroxyapatite composite structures by stereolithography.

    PubMed

    Ronca, A; Ambrosio, L; Grijpma, D W

    2013-04-01

    The preparation of scaffolds to facilitate the replacement of damaged tissues and organs by means of tissue engineering has been much investigated. The key properties of the biomaterials used to prepare such scaffolds include biodegradability, biocompatibility and a well-defined three-dimensional 3-Dpore network structure. In this study a poly(D,L-lactide)/nanosized hydroxyapatite (PDLLA/nano-Hap) composite resin was prepared and used to fabricate composite films and computer designed porous scaffolds by micro-stereolithography, mixing varying quantities of nano-Hap powder and a liquid photoinitiator into a photo-crosslinkable PDLLA-diacrylate resin. The influence of nano-Hap on the rheological and photochemical properties of the resins was investigated, the materials being characterized with respect to their mechanical, thermal and morphological properties after post-preparation curing. In the cured composites stiffness was observed to increase with increasing concentration of nanoparticles. A computer designed construct with a pore network based on the Schwarz architecture was fabricated by stereolithography using PDLLA/nano-Hap composite resins. PMID:23232210

  6. Structure and dynamics of nano-sized raft-like domains on the plasma membrane

    NASA Astrophysics Data System (ADS)

    Herrera, Fernando E.; Pantano, Sergio

    2012-01-01

    Cell membranes are constitutively composed of thousands of different lipidic species, whose specific organization leads to functional heterogeneities. In particular, sphingolipids, cholesterol and some proteins associate among them to form stable nanoscale domains involved in recognition, signaling, membrane trafficking, etc. Atomic-detail information in the nanometer/second scale is still elusive to experimental techniques. In this context, molecular simulations on membrane systems have provided useful insights contributing to bridge this gap. Here we present the results of a series of simulations of biomembranes representing non-raft and raft-like nano-sized domains in order to analyze the particular structural and dynamical properties of these domains. Our results indicate that the smallest (5 nm) raft domains are able to preserve their distinctive structural and dynamical features, such as an increased thickness, higher ordering, lower lateral diffusion, and specific lipid-ion interactions. The insertion of a transmembrane protein helix into non-raft, extended raft-like, and raft-like nanodomain environments result in markedly different protein orientations, highlighting the interplay between the lipid-lipid and lipid-protein interactions.

  7. Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Zargar, Rayees Ahmad; Arora, Manju; Khurram Hafiz, Aurangzeb

    2015-04-01

    Nanosized ZnO particles derived from chemical co-precipitation route were used for casting ZnO films by screen printing method followed by sintering at two different temperatures. The variation in structural, optical and electrical properties of these films with temperature have been investigated by XRD, SEM, FTIR, Raman, UV-VIS, EPR and four probe analytical techniques. XRD patterns of these films exhibit polycrystalline nature with hexagonal wurtzite structure and SEM images reveal the smooth, dense and without any cracks/damage porous surface morphology. Infrared transmission spectra shows peaks pertaining to Zn-O stretching modes and their multiphonon modes. While Raman spectra exhibited strong peaks of E2 (high) phonon and overtone of surface phonon mode at 429 cm-1 and 1144 cm-1 respectively with weak components of LO and TO branches. The direct band gap energy of these films showed narrowing of band gap from 3.21 eV to 3.12 eV on increasing sintering temperature from 500 °C to 600 °C. DC conductivity measurements confirmed semiconducting behaviour and showed lowering of activation energy. EPR spectra showed single narrow line resonance signal of g-value ~ 1.9469 due to oxygen vacancies which are produced during synthesis of ZnO nanoparticles by sol-gel process. These studies revealed that on increasing sintering temperature the crystallinity of the film improves with reduction in lattice deformations in these screen printed ZnO films.

  8. High reactivity of nanosized niobium oxide cluster cations in methane activation: A comparison with vanadium oxides.

    PubMed

    Ding, Xun-Lei; Wang, Dan; Wu, Xiao-Nan; Li, Zi-Yu; Zhao, Yan-Xia; He, Sheng-Gui

    2015-09-28

    The reactions between methane and niobium oxide cluster cations were studied and compared to those employing vanadium oxides. Hydrogen atom abstraction (HAA) reactions were identified over stoichiometric (Nb2O5)N(+) clusters for N as large as 14 with a time-of-flight mass spectrometer. The reactivity of (Nb2O5)N(+) clusters decreases as the N increases, and it is higher than that of (V 2O5)N(+) for N ≥ 4. Theoretical studies were conducted on (Nb2O5)N(+) (N = 2-6) by density functional calculations. HAA reactions on these clusters are all favorable thermodynamically and kinetically. The difference of the reactivity with respect to the cluster size and metal type (Nb vs V) was attributed to thermodynamics, kinetics, the electron capture ability, and the distribution of the unpaired spin density. Nanosized Nb oxide clusters show higher HAA reactivity than V oxides, indicating that niobia may serve as promising catalysts for practical methane conversion. PMID:26429016

  9. Cellulose fibers modified with nano-sized antimicrobial polymer latex for pathogen deactivation.

    PubMed

    Pan, Yuanfeng; Xiao, Huining; Cai, Pingxiong; Colpitts, Meaghan

    2016-01-01

    Antimicrobial cellulose fibers and paper products are of great importance for various applications. In this work, novel core-shell antimicrobial latexes based on hydrophobic acrylate monomers and antimicrobial macromonomer (GPHGH) were successfully prepared via a seeded semi-continuous emulsion copolymerization in the presence of a cationic surfactant. The surface properties as well as size of latex were tailored by varying the amount of GPHGH incorporated during the copolymerization. The resulting cationic nano-sized latexes showed the strong adsorption and formed monolayer on the surfaces of bleached sulfite fibers, thus rendering the cellulose fibers antimicrobial. An excellent antimicrobial activity (>99.99% inhibition) of modified fiber toward Escherichia coli was achieved at 0.3wt% of latex dosage (on dry fibers). Results of transmission electron microscopy (TEM) observation confirmed that the particles obtained indeed possessed a desired core-shell structure. The latexes themselves exhibited high antimicrobial activities against E. coli with the minimum inhibitory concentration (MIC) as low as 6.25ppm (similar to that of pure guanidine-based polymer). Moreover, the mechanical strength of the hand-sheets made from latex-modified cellulose fibers was also improved due to the filming of the latex on fiber surfaces. PMID:26453856

  10. Physical and electromagnetic properties of nanosized Gd substituted Mg-Mn ferrites by solution combustion method

    NASA Astrophysics Data System (ADS)

    Lwin, Nilar; Ahmad Fauzi, M. N.; Sreekantan, Srimala; Othman, Radzali

    2015-03-01

    Nanosized powders of Gd substituted Mg-Mn ferrites synthesized by solution combustion method using high purity metal nitrates are presented. These powders were calcined, compacted and sintered at 1250 °C. The powders were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The effect of Gd substitution on phase formation, microstructure and bulk density was also studied. Gd2O3 facilitates the formation of a secondary phase on the grain boundary which suppresses abnormal grain growth. The bulk density was found to decrease from 4.26 to 3.38 g/cm3 with an increase of Gd substitution, but the electrical resistivity was increased. Ferrite with a low dielectric constant in the range of 6-12 was observed and there was no maximum dielectric loss in the frequency range measured to 1 GHz. A decrease in saturation magnetization was also observed by a small fraction of Gd substitution. Correlation between magnetic properties and physical properties were discussed.

  11. Impacts of a nanosized ceria additive on diesel engine emissions of particulate and gaseous pollutants.

    PubMed

    Zhang, Junfeng; Nazarenko, Yevgen; Zhang, Lin; Calderon, Leonardo; Lee, Ki-Bum; Garfunkel, Eric; Schwander, Stephan; Tetley, Teresa D; Chung, Kian Fan; Porter, Alexandra E; Ryan, Mary; Kipen, Howard; Lioy, Paul J; Mainelis, Gediminas

    2013-11-19

    Fuel additives incorporating nanosized ceria have been increasingly used in diesel engines as combustion promoters. However, few studies have assessed the impact of these nanotechnology-based additives on pollutant emissions. Here, we systematically compare emission rates of particulate and gaseous pollutants from a single-cylinder, four-cycle diesel engine using fuel mixes containing nanoceria of varying concentrations. The test fuels were made by adding different amounts of a commercial fuel additive Envirox into an ultralow-sulfur diesel fuel at 0 (base fuel), 0.1-, 1-, and 10-fold the manufacturer-recommended concentration of 0.5 mL Envirox per liter of fuel. The addition of Envirox resulted in ceria-concentration-dependent emission reductions of CO2, CO, total particulate mass, formaldehyde, acetaldehyde, acrolein, and several polycyclic aromatic hydrocarbons. These reductions at the manufacturer-recommended doping concentration, however, were accompanied by a substantial increase of certain other air pollutants, specifically the number of ultrafine particles (+32%), NO(x) (+9.3%), and the particle-phase benzo[a]pyrene toxic equivalence quotient (+35%). Increasing fuel ceria concentrations also led to decreases in the size of emitted particles. Given health concerns related to ultrafine particles and NO(x), our findings call for additional studies to further evaluate health risks associated with the use of nanoceria additives in various engines under various operating conditions. PMID:24144266

  12. Grain size-dependent magnetic and electric properties in nanosized YMnO3 multiferroic ceramics

    PubMed Central

    2011-01-01

    Magnetic and electric properties are investigated for the nanosized YMnO3 samples with different grain sizes (25 nm to 200 nm) synthesized by a modified Pechini method. It shows that magnetic and electric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 52 to 74 K. A corresponding shift of the dielectric anomaly is observed, indicating a strong correlation between the electric polarization and the magnetic ordering. Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters. Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2). PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s PMID:21711722

  13. Chances and limitations of nanosized titanium dioxide practical application in view of its physicochemical properties

    NASA Astrophysics Data System (ADS)

    Bogdan, Janusz; Jackowska-Tracz, Agnieszka; Zarzyńska, Joanna; Pławińska-Czarnak, Joanna

    2015-02-01

    Nanotechnology is a field of science that is nowadays developing in a dynamic way. It seems to offer almost endless opportunities of contribution to many areas of economy and human activity, in general. Thanks to nanotechnology, the so-called nanomaterials can be designed. They present structurally altered materials, with their physical, chemical and biological properties entirely differing from properties of the same materials manufactured in microtechnology. Nanotechnology creates a unique opportunity to modify the matter at the level of atoms and particles. Therefore, it has become possible to obtain items displaying new, useful properties, i.e. self-disinfecting and self-cleaning surfaces. Those surfaces are usually covered by a thin layer of a photocatalyst. The role of the photocatalyst is most of the time performed by the nanosized titanium dioxide (nano-TiO2). Excitation of nano-TiO2 by ultraviolet radiation initiates advanced oxidation processes and reactions leading to the creation of oxygen vacancies that bind water particles. As a result, photocatalytic surfaces are given new properties. Those properties can then be applied in a variety of disciplines, such as medicine, food hygiene, environmental protection or building industry. Practically, the applications include inactivation of microorganisms, degradation of toxins, removing pollutants from buildings and manufacturing of fog-free windows or mirrors.

  14. Microwave absorption behavior of ZnO whisker modified by nanosized Fe3O4 particles.

    PubMed

    Hu, Shuchun; Wu, Guofeng; Huang, Zhenhao; Chen, Xiaolang

    2010-11-01

    Tetra-needle-like ZnO whisker was magnetic modified through in situ synthesis of nanosized Fe3O4 particles on the surface of the whisker, and the microwave absorption behavior of the as-prepared product was investigated in detail. The result of the comparative microwave absorbing experiment showed that the magnetic modified ZnO whisker appeared more superior property of microwave absorption than that of the original ZnO whisker in 2-18 GHz. Further investigation indicated that the microwave absorption behavior of the product was influenced by ferrite content and Fe3O4 particles' distribution in the product. When the ferrite content of the product changed from 2 wt% to 9 wt%, the microwave absorbing ability of the product was increased; then, the microwave absorbing ability of the product decreased with the further increasing of ferrite content from 9 wt% to 16 wt%. The product with uniform distribution of Fe3O4 particles showed better microwave absorption property than that with irregular distribution of Fe3O4 particles, and this result inferred that the biphase interface between ZnO and Fe3O4 contributed to microwave absorption through interface polarization. PMID:21137989

  15. Low-Temperature Oxidation of Fine UO2 Powders: A Process of Nanosized Domain Development.

    PubMed

    Leinders, Gregory; Pakarinen, Janne; Delville, Rémi; Cardinaels, Thomas; Binnemans, Koen; Verwerft, Marc

    2016-04-18

    The nanostructure and phase evolution in low-temperature oxidized (40-250 °C), fine UO2 powders (<200 nm) have been investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The extent of oxidation was also measured via in situ thermogravimetric analysis. The oxidation of fine powders was found to proceed differently as compared to oxidation of coarse-grained UO2. No discrete surface oxide layer was observed and no U3O8 was formed, despite the high degree of oxidation (up to O/U = 2.45). Instead, nanosized (5-15 nm) amorphous nuclei (interpreted as amorphous UO3), unmodulated and modulated U4O9, and a continuous range of U3O7-z phases with varying tetragonal distortion (c/a > 1) were observed. Oxidation involves formation of higher uranium oxides in nanodomains near the grain surface which, initially, have a disordered defect structure ("disordered U4O9"). As oxidation progresses, domain growth increases and the long-period modulated structure of U4O9 develops ("ordered U4O9"). A similar mechanism is understood to happen also in U3O7-z. PMID:27015279

  16. Adsorption behavior and mechanism of perfluorooctane sulfonate on nanosized inorganic oxides.

    PubMed

    Lu, Xinyu; Deng, Shubo; Wang, Bin; Huang, Jun; Wang, Yujue; Yu, Gang

    2016-07-15

    Adsorption of perfluorooctane sulfonate (PFOS) on manufactured nanoparticles (NPs) is critical for understanding their transport and fate in aquatic environments. In this study, the adsorption behavior of PFOS on nanosized Al2O3, Fe2O3, SiO2 and TiO2 was examined in terms of adsorption isotherms and influences of pH, ionic strength and heavy metallic cations. The nano-oxides had much higher adsorption capacities than bulk particles due to higher surface hydroxyl density. PFOS adsorption showed strong pH dependence due to different species of surface hydroxyl groups on nano-oxides. Besides electrostatic interaction, sulfonic group of PFOS possibly formed hydrogen bonds on the surface of nano-oxides. Because of the bridging effect in the co-adsorption process, the coexisting PFOS and heavy metallic cations greatly enhanced their adsorption onto the nano-oxides. Comparative adsorption of different perfluorinated sulfonates indicated the possible formation of bilayer PFOS adsorption on the nano-oxides, leading to the enhanced Cu(II) adsorption on the sulfonic groups of PFOS on the surfaces through electrostatic interaction. PMID:27127908

  17. Influence of acid precursors on physicochemical properties of nanosized titania synthesized by thermal-hydrolysis method

    SciTech Connect

    Rajesh, B.; Sasirekha, N.R.; Chen, Y.-W.

    2008-03-04

    The influence of nature and concentration of acid species on surface morphology and physicochemical properties of titania particles synthesized by direct thermal hydrolysis of titanium tetrachloride was investigated. The acids used were hydrochloric acid, nitric acid, sulfuric acid, and perchloric acid with a concentration of 3 M. Thermal hydrolysis of titanium tetrachloride in hydrochloric acid and perchloric acid with molar ratios of [H{sup +}]/[Ti{sup 4+}] = 0.5, 1.0, 1.5, and 2.0, respectively, was used to study the effect of acid concentration. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dynamic light scattering, and thermogravimetric analysis. Characterization of the samples by X-ray diffraction studies revealed the influence of acid species on the phase transformation of titania. Samples prepared by hydrochloric acid, nitric acid, and perchloric acid formed rutile phase with rhombus primary particles, while sulfuric acid resulted in anatase phase with flake-shaped primary particles. Transmission electron microscopy and dynamic light scattering results confirmed the nanosized titania particles and the agglomeration of primary particles to form secondary particles in spherical shape. The particle size of titania prepared using perchloric acid was smaller than those prepared with other acid sources. A direct correlation between [H{sup +}]/[Ti{sup 4+}] ratio and particle size of titania was observed.

  18. Fatigue and healing properties of bituminous mastics reinforced with nano-sized additives

    NASA Astrophysics Data System (ADS)

    Santagata, Ezio; Baglieri, Orazio; Tsantilis, Lucia; Dalmazzo, Davide; Chiappinelli, Giuseppe

    2016-03-01

    The research work described in the paper focused on fatigue and healing properties of bituminous mastics reinforced with nano-sized additives. Commercially available multiwall carbon nanotubes (CNTs) and montmorillonite nanoclay (NC) were combined with a single base bitumen and a standard mineral filler to produce bituminous mastics. These blends were prepared in the laboratory by making use of a technique consisting in simple shear mixing followed by sonication. Fatigue behaviour of mastics under repeated loading was investigated by means of time sweeps performed in the strain-controlled mode at various amplitudes. Healing potential was assessed by adopting a testing protocol specifically conceived to discriminate between recovery of damage induced by fatigue loading and other artefact phenomena which may affect material response. All rheological measurements were carried out with a dynamic shear rheometer in the parallel plates geometry. Outcomes of the experimental investigation were found to be highly dependent on the nature of additive type, as a result of the key role played by interaction mechanisms that nano-particles can establish within the bituminous mastic.

  19. Dispersion-precipitation synthesis of nanosized magnetic iron oxide for efficient removal of arsenite in water.

    PubMed

    Cheng, Wei; Xu, Jing; Wang, Yajie; Wu, Feng; Xu, Xiuyan; Li, Jinjun

    2015-05-01

    Nanosized magnetic iron oxide was facilely synthesized by a dispersion-precipitation method, which involved acetone-promoted precipitation of colloidal hydrous iron oxide nanoparticles and subsequent calcination of the precipitate at 250°C. Characterization by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, nitrogen sorption, and vibrating-sample magnetometry revealed that the material was a composite of α-Fe2O3 and γ-Fe2O3 with primary particle size of 15-25 nm and specific surface area of 121 m(2)/g, as well as superparamagnetic property. The material was used as adsorbent for the removal of arsenite in water. Batch experiments showed that the adsorption isotherms at pH 3.0-11.0 fit the Langmuir equation and the adsorption obeys pseudo-second-order kinetics. Its maximum sorption capability for arsenite is 46.5 mg/g at pH 7.0. Coexisting nitrate, carbonate, sulfate, chloride, and fluoride have no significant effect on the removal efficiency of arsenite, while phosphate and silicate reduce the removal efficiency to some extent. The As(III) removal mechanism is chemisorption through forming inner-sphere surface complexes. The efficiency of arsenic removal is still maintained after five cycles of regeneration-reuse. PMID:25612934

  20. Synthesis, performance, and modeling of immobilized nano-sized magnetite layer for phosphate removal.

    PubMed

    Zach-Maor, Adva; Semiat, Raphael; Shemer, Hilla

    2011-05-15

    A homogeneous layer of nano-sized magnetite particles (<4 nm) was synthesized by impregnation of modified granular activated carbon (GAC) with ferric chloride, for effective removal of phosphate. A proposed mechanism for the modification and formation of magnetite onto the GAC is specified. BET results showed a significant increase in the surface area of the matrix following iron loading, implying that a porous nanomagnetite layer was formed. Batch adsorption experiments revealed high efficiency of phosphate removal, by the newly developed adsorbent, attaining maximum adsorption capacity of 435 mg PO(4)/g Fe (corresponding to 1.1 mol PO(4)/mol Fe(3)O(4)). It was concluded that initially phosphate was adsorbed by the active sites on the magnetite surface, and then it diffused into the interior pores of the nanomagnetite layer. It was demonstrated that the latter is the rate-determining step for the process. Innovative correlation of the diffusion mechanism with the unique adsorption properties of the synthesized adsorbent is presented. PMID:21397244

  1. Thermodynamic stability of nanosized multicomponent bubbles/droplets: The square gradient theory and the capillary approach

    SciTech Connect

    Wilhelmsen, Øivind Bedeaux, Dick; Kjelstrup, Signe; Reguera, David

    2014-01-14

    Formation of nanosized droplets/bubbles from a metastable bulk phase is connected to many unresolved scientific questions. We analyze the properties and stability of multicomponent droplets and bubbles in the canonical ensemble, and compare with single-component systems. The bubbles/droplets are described on the mesoscopic level by square gradient theory. Furthermore, we compare the results to a capillary model which gives a macroscopic description. Remarkably, the solutions of the square gradient model, representing bubbles and droplets, are accurately reproduced by the capillary model except in the vicinity of the spinodals. The solutions of the square gradient model form closed loops, which shows the inherent symmetry and connected nature of bubbles and droplets. A thermodynamic stability analysis is carried out, where the second variation of the square gradient description is compared to the eigenvalues of the Hessian matrix in the capillary description. The analysis shows that it is impossible to stabilize arbitrarily small bubbles or droplets in closed systems and gives insight into metastable regions close to the minimum bubble/droplet radii. Despite the large difference in complexity, the square gradient and the capillary model predict the same finite threshold sizes and very similar stability limits for bubbles and droplets, both for single-component and two-component systems.

  2. Nanosized tungsten carbide synthesized by a novel route at low temperature for high performance electrocatalysis

    PubMed Central

    Yan, Zaoxue; Cai, Mei; Shen, Pei Kang

    2013-01-01

    Tungsten carbide (WC) is a widely used engineering material which is usually prepared at high temperature. A new mechanism for synthesizing nanoscaled WC at ultralow temperature has been discovered. This discovery opens a novel route to synthesize valuable WC and other carbides at a cost-efficient way. The novel formation mechanism is based on an ion-exchange resin as carbon source to locally anchor the W and Fe species. As an intermediate, FeWO4 can be formed at lower temperature, which can be directly converted into WC along with the carbonization of resin. The size of WC can be less than 2 nm. The catalyst made with Pt nanoparticles supported on nanosized WC-GC (WC-graphitized carbon) shows enhanced electrocatalytic activity for oxygen reduction reaction. The result also indicates that the Pt nanoparticles deposited on WC-GC are dominated by Pt (111) plane and shows a mass activity of 257.7 mA mg−1Pt@0.9 V. PMID:23571654

  3. Nanosized substructure of heat-treated high-strength cast iron

    NASA Astrophysics Data System (ADS)

    Chizhik, S. A.; Kuznetsova, T. A.; Khudolei, A. L.; Komarov, A. I.; Komarova, V. I.; Vasilenko, M. S.

    2013-09-01

    This paper presents the results of investigating the microstructure of high-strength VChTG cast iron by the methods of scanning electron and atomic-force microscopy and x-ray phase analysis. A nanosized substructure of ferrite, perlite, and graphite phases of the cast iron has been revealed. An ordered sandwich multilevel structure of ferrite in the initial VChTG in the form of steps of width 400-600 nm and height about 100 nm consisting of bands of width 30 nm and interband height 3-10 nm has been established. It has been shown that the width of cementite lamellae in perlite varies from 200 to 400 nm, and the lamellae themselves consist, in turn, of sublamellae of width 30 nm. Graphite inclusions consist of layered crystallites of diameter 5-200 nm with a thickness of individual layers of 0.7-1.4 nm. Upon heat treatment the size of bainite subgrains is 100-300 nm. It has been shown that there is s relation between the size of the shift of subgrains for heat-treated VChTG revealed by atomic-force microscopy and microdistortions of the α-phase lattice determined by x-ray analysis.

  4. Templated CaCO3 Crystallization by Submicrometer and Nanosized Fibers.

    PubMed

    Neira-Carrillo, Andrónico; Gentsch, Rafael; Börner, Hans G; Acevedo, Diego Fernando; Barbero, Cesar Alfredo; Cölfen, Helmut

    2016-09-01

    Electrospun submicrometer-sized poly(ε-caprolactone) (PCL) meshes and nanosized multiwalled carbon nanotubes (MWCNTs) were used as a template for preparing porous and interconnected inorganic-organic hybrid materials composed of CaCO3. Herein, we describe the proportion and incorporation method of submicrometer-sized plasma-treated PCL meshes over areas >1 mm(2) with CaCO3 using three crystallization methods including the use of poly(acrylic acid) (PAA). We found that flexible and rigid acid-functionalized MWCNTs showed a clear capacity and effects to penetrate calcite particles. MWCNTs interacted differently with the individual growth planes of CaCO3, indicating that fibers can undergo changes depending on sulfonate or carboxylate groups, adopt different orientations in solution, and thereby elicit changes in CaCO3 morphology. In summary, the use of PCL and acidic MWCNT fibers as an additive for substrate templates and experimental crystallization provides a viable approach for studying various aspects of biomineralization, including the production of controlled particles, control of porosities, and defined morphologies at microscale and nanoscale levels. PMID:27529799

  5. Characterization of Al and Fe nanosized powders synthesized by high energy mechanical milling

    SciTech Connect

    Mhadhbi, Mohsen; Khitouni, Mohamed Azabou, Myriam; Kolsi, Abdelwaheb

    2008-07-15

    The process of nanocrystalline structure formation during mechanical milling was studied in Al and Fe powders. A detailed microstructural study of powder samples was carried out by X-ray diffraction experiments as a function of milling time. As a result, nanosized powders have been synthesized with microstructures showing a significant decrease of the coherent diffraction domains and the creation of a large number of linear defects, which induce microstrains. SEM results show that welding of very small particles to the surfaces of larger particles occurred and that the powder particles tended to form a matrix of randomly welded thin layers of highly deformed particles. Calorimetric measurements, as a function of milling time, indicated the decrease of the melting point of Al powder and at early stages it can be seen that initially endothermic peak was divided to two endothermic melting peaks. This is probably due to the oxide layer around the Al grains. In the case of Fe powder, the DSC measurements show a broad exothermal peak occurring over quite a large temperature interval, corresponding to the strain release and grain growth.

  6. Elastic Properties of Silicon Carbide Nanowires and Nanosize Grains up to 75 GPa

    NASA Astrophysics Data System (ADS)

    Zerda, T. W.

    2010-03-01

    Silicon carbide nanowires of average diameter of 30 nm and narrow size distribution were sintered from carbon nanotubes and silicon at 1200^oC. X-ray diffraction measurements of those SiC nanowires were conducted in a diamond anvil cell at room temperature and pressures up to 55 GPa applied by an alcohol medium. We used the same technique to study SiC grains of various sizes. The pressure-dependent volumes of the respective unit cells were calculated from the diffraction data, and the bulk moduli extracted from these studies depended on the particle size: 260 GPa for the 20 nm grains, 198 GPa for the 50 nm grains, and 193 GPa for the 130 nm grains. The bulk modulus of the 30 nm SiC nanowire was found to be 240 GPa. The bulk modulus study was extended to 75 GPa of pressure by use of a diamond anvil cell cryogenically loaded with an argon pressure medium. The bulk modulus was unchanged in this extended pressure range. The elevated bulk modulus of 20 nm grains is explained by the core-shell model developed by Palosz, et al. The core atoms exhibit all the properties associated with the bulk material, but the interatomic distances of shell atoms may differ. With nano-sized materials, a much larger percentage of the constituent atoms belong to the shell.

  7. Antimicrobial action effect and stability of nanosized silica hybrid Ag complex.

    PubMed

    Kim, Hwa-Jung; Park, Hae-Jun; Choi, Seong-Ho

    2011-07-01

    Nanosized silica hybrid silver complex (NSS) showing strong antifungal activity, in which nanosilver (nano-Ag) was bound to silica (SiO2) molecules, was synthesized via gamma-irradiation at room temperature. NSS was characterized via field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDXS), ultraviolet-visible (UV-Vis) spectrophotometer, and thermogravimetric analysis (TGA). The FESEM images and EDXS data showed that well-dispersed 3-to-10-nm Ag nanoparticles (core part) were loaded onto the outer parts of 5-to-20 nm SiO2 nanoparticles. The antifungal efficiency of NSS was evaluated against Rhizoctonia solani, Botrytis cinerea, and Colletotrichum gloeosporioides. In the case of Rhizoctonia solani, the growth rate was decreased typically by more than 90% at a 6 microg/ml concentration of NSS as a medium additive. The antifungal-action mechanism was investigated via transmission electron microscopy (TEM) analysis of the NSS treatment against Botrytis cinerea. The stability and antimicrobial activity of NSS were determined, using the plate culture method, from several water samples containing NSS after 7-day NSS treatment. Moreover, the NSS solution maintained stable antifungal activity for at least 24 mos. These results suggest that NSS, an environment-friendly nanomaterial, can be used as strongly effective growth inhibitor of various microorganisms, making it applicable to diverse antimicrobial-control systems. PMID:22121607

  8. Growth and properties of silicon heterostructures with buried nanosize Mg2Si clusters

    NASA Astrophysics Data System (ADS)

    Galkin, N. G.; Galkin, K. N.

    2005-06-01

    The technology of solid-phase growth of nanosize islands of magnesium suicide on Si (111) 7x7 with narrow distributions of lateral size and height (60 - 80 and 5 - 7 nanometers, respectively) and density of up to 2x 109 sm-2 is proposed. A 20-50 nm thick Si layer has been grown upon these islands. Basing on the data of AES, EELS, AFM and JR spectroscopy, a conclusion is made that the Mg2Si islands remain in depth of the Si layer. The suggestion is made that sizes, density and crystal structure of the buried magnesium suicide clusters preserves. It is shown, that the system of three as-grown layers of buried clusters has smoother surface than the one layer system. The contribution of the Mg2Si clusters into the dielectric function is observed at the energy 0.8-1.2 eV, it is maximal if the clusters are localized on the silicon surface. It is shown, that with increase of the number of Mg2Si cluster layers their contribution increases into the effective number of electrons per a unit cell and effective dielectric function of the sample.

  9. Molecular Mechanisms of Nanosized Titanium Dioxide–Induced Pulmonary Injury in Mice

    PubMed Central

    Sang, Xuezi; Cui, Yaling; Wang, Xiaochun; Gui, Suxin; Tan, Danlin; Zhu, Min; Zhao, Xiaoyang; Sheng, Lei; Wang, Ling; Hong, Fashui; Tang, Meng

    2013-01-01

    The pulmonary damage induced by nanosized titanium dioxide (nano-TiO2) is of great concern, but the mechanism of how this damage may be incurred has yet to be elucidated. Here, we examined how multiple genes may be affected by nano-TiO2 exposure to contribute to the observed damage. The results suggest that long-term exposure to nano-TiO2 led to significant increases in inflammatory cells, and levels of lactate dehydrogenase, alkaline phosphate, and total protein, and promoted production of reactive oxygen species and peroxidation of lipid, protein and DNA in mouse lung tissue. We also observed nano-TiO2 deposition in lung tissue via light and confocal Raman microscopy, which in turn led to severe pulmonary inflammation and pneumonocytic apoptosis in mice. Specifically, microarray analysis showed significant alterations in the expression of 847 genes in the nano-TiO2-exposed lung tissues. Of 521 genes with known functions, 361 were up-regulated and 160 down-regulated, which were associated with the immune/inflammatory responses, apoptosis, oxidative stress, the cell cycle, stress responses, cell proliferation, the cytoskeleton, signal transduction, and metabolic processes. Therefore, the application of nano-TiO2 should be carried out cautiously, especially in humans. PMID:23409001

  10. Stroke Damage Is Exacerbated by Nano-Size Particulate Matter in a Mouse Model

    PubMed Central

    Liu, Qinghai; Babadjouni, Robin; Radwanski, Ryan; Cheng, Hank; Patel, Arati; Hodis, Drew M.; He, Shuhan; Baumbacher, Peter; Russin, Jonathan J.; Morgan, Todd E.; Sioutas, Constantinos; Finch, Caleb E.; Mack, William J.

    2016-01-01

    This study examines the effects of nano-size particulate matter (nPM) exposure in the setting of murine reperfused stroke. Particulate matter is a potent source of inflammation and oxidative stress. These processes are known to influence stroke progression through recruitment of marginally viable penumbral tissue into the ischemic core. nPM was collected in an urban area in central Los Angeles, impacted primarily by traffic emissions. Re-aerosolized nPM or filtered air was then administered to mice through whole body exposure chambers for forty-five cumulative hours. Exposed mice then underwent middle cerebral artery occlusion/ reperfusion. Following cerebral ischemia/ reperfusion, mice exposed to nPM exhibited significantly larger infarct volumes and less favorable neurological deficit scores when compared to mice exposed to filtered air. Mice exposed to nPM also demonstrated increases in markers of inflammation and oxidative stress in the region of the ischemic core. The findings suggest a detrimental effect of urban airborne particulate matter exposure in the setting of acute ischemic stroke. PMID:27071057