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Sample records for magnetite nano-particle surface

  1. An optimized surface plasmon photovoltaic structure using energy transfer between discrete nano-particles.

    PubMed

    Lin, Albert; Fu, Sze-Ming; Chung, Yen-Kai; Lai, Shih-Yun; Tseng, Chi-Wei

    2013-01-14

    Surface plasmon enhancement has been proposed as a way to achieve higher absorption for thin-film photovoltaics, where surface plasmon polariton(SPP) and localized surface plasmon (LSP) are shown to provide dense near field and far field light scattering. Here it is shown that controlled far-field light scattering can be achieved using successive coupling between surface plasmonic (SP) nano-particles. Through genetic algorithm (GA) optimization, energy transfer between discrete nano-particles (ETDNP) is identified, which enhances solar cell efficiency. The optimized energy transfer structure acts like lumped-element transmission line and can properly alter the direction of photon flow. Increased in-plane component of wavevector is thus achieved and photon path length is extended. In addition, Wood-Rayleigh anomaly, at which transmission minimum occurs, is avoided through GA optimization. Optimized energy transfer structure provides 46.95% improvement over baseline planar cell. It achieves larger angular scattering capability compared to conventional surface plasmon polariton back reflector structure and index-guided structure due to SP energy transfer through mode coupling. Via SP mediated energy transfer, an alternative way to control the light flow inside thin-film is proposed, which can be more efficient than conventional index-guided mode using total internal reflection (TIR).

  2. Can Nano-Particle Melt below the Melting Temperature of Its Free Surface Partner?

    NASA Astrophysics Data System (ADS)

    Sui, Xiao-Hong; Wang, Zong-Guo; Kang, Kai; Qin, Shao-Jing; Wang, Chui-Lin

    2015-02-01

    The phonon thermal contribution to the melting temperature of nano-particles is inspected. The discrete summation of phonon states and its corresponding integration form as an approximation for a nano-particle or for a bulk system have been analyzed. The discrete phonon energy levels of pure size effect and the wave-vector shifts of boundary conditions are investigated in detail. Unlike in macroscopic thermodynamics, the integration volume of zero-mode of phonon for a nano-particle is not zero, and it plays an important role in pure size effect and boundary condition effect. We find that a nano-particle will have a rising melting temperature due to purely finite size effect; a lower melting temperature bound exists for a nano-particle in various environments, and the melting temperature of a nano-particle with free boundary condition reaches this lower bound. We suggest an easy procedure to estimation the melting temperature, in which the zero-mode contribution will be excluded, and only several bulk quantities will be used as input. We would like to emphasize that the quantum effect of discrete energy levels in nano-particles, which is not present in early thermodynamic studies on finite size corrections to melting temperature in small systems, should be included in future researches.

  3. Fabrication of magnetite nano particles and modification with metal organic framework of Zn(2+) for sorption of doxycyline.

    PubMed

    Ghassemi Nooreini, Mahsa; Ahmad Panahi, Homayon

    2016-10-15

    This study presents a novel method for synthesis and characterization of a metal-organic framework and application in drug delivery. The first step was synthesis of amino functionalized magnetite that was then modified by a metal-organic framework of Zn(2+). This newly developed nano-sorbent was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer and x-ray diffraction. Doxycycline was loaded to the nano-sorbent and effects of the variable parameters, kinetics of adsorption, release and capacity of adsorption were investigated. Test results specified maximum sorption of 21.5mgg(-1) for doxycycline in conditions of nano-sorbent at pH 7 and optimum time of 10min. Equilibrium adsorption data were analyzed by the Langmuir, Freundlich and Temkin models. Results showed that about 40% of doxycycline was released in simulated gastric fluid for the 30min and more than 70% was released in simulated intestinal fluid during 12h. These results were satisfactory and demonstrate that this new nano-sorbent modified with metal-organic framework had a good level of efficiency for drug delivery of doxycycline.

  4. Surface passivation of silicon nanowires based metal nano-particle assisted chemical etching for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Ben Rabha, Mohamed; Khezami, Lotfi; Jemai, Abdelbasset Bessadok; Alhathlool, Raed; Ajbar, Abdelhamid

    2017-03-01

    Metal Nano-particle Assisted Chemical Etching (MNpACE) is an extraordinary developed wet etching method for producing uniform semiconductor nanostructure (silicon nanowires) from patterned metallic film on crystalline silicon surface. The metal films facilitate the etching in HF and H2O2 solution and produce silicon nanowires (SiNWs).The creation of different SiNWs morphologies by changing the etching time and its effects on optical and optoelectronic properties was investigated. The combination effect of formed SiNWs and stain etching treatment in acid (HF/HNO3/H2O) solution on the surface morphology of Si wafers as well as on the optical and optoelectronic properties especially a PL response at 640 nm are presented. As a results, the effective lifetime (τeff) and surface recombination velocity (Seff) evolution of SiNWs after stain etching treatment showed significant improvements and less than 1% reflectance was achieved over the wavelength range of 400-800 nm and more than 36% reduction was observed compared to untreated surface. It has, thus, been demonstrated that all these factors may lead to improved energy efficiency from 8% to nearly 14.2% for a cell with SiNWs treated in acid (HF/HNO3/H2O) solution.

  5. Conditions for laser-induced plasma to effectively remove nano-particles on silicon surfaces

    NASA Astrophysics Data System (ADS)

    Han, Jinghua; Luo, Li; Zhang, Yubo; Hu, Ruifeng; Feng, Guoying

    2016-09-01

    Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave. The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients, making the particles easier to be removed. Laser plasma can ionize and even vaporize particles more significantly than an incident laser and, therefore, it can remove the particles more efficiently. The laser plasma shock wave plays a dominant role in removing particles, which is attributed to its strong burst force. The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface. In order to obtain the working conditions for particle removal, the removal mechanism, as well as the temporal and spatial characteristics of velocity, propagation distance and pressure of shock wave have been researched. On the basis of our results, the conditions for nano-particle removal are achieved. Project supported by the National Natural Science Foundation of China (Grant No. 11574221).

  6. Surface Plasmon Resonance Characteristics of Optical Fiber Incorporated with Au Nano-Particles in Cladding Region.

    PubMed

    Ju, Seongmin; Jeong, Seongmook; Kim, Youngwoong; Lee, Sang-Hyun; Han, Won-Taek

    2016-06-01

    A novel surface plasmon resonance (SPR) sensor based on specialty optical fiber having its cladding doped with Au nano-particles (NPs) was developed by modified chemical vapor deposition process. To optimize the SPR absorption and sensitivity of the fiber SPR sensor, effect of the fiber length (20 cm-90 cm) on sensing capability of refractive index (n = 1.418-1.448) was investigated. Absorption peaks appearing at 392 and 790 nm were due to SPR from Au NPs in the cladding region of the optical fiber. The SPR was found to occur at particular wavelengths around 390 nm for the corresponding refractive indices regardless of the length of the fiber, increased with the increase of the index. The measured SPR sensitivities (wavelength/RIU) of the fiber were estimated to be 407 nm/RIU, 217 nm/RIU, and 54 nm/RIU with the fiber lengths of 20 cm, 45 cm, and 90 cm, respectively. The SPR absorption intensity and FWHM decreased with the increase of the fiber length because the propagation loss of the signal through the fiber cladding region increased.

  7. Metallic nano-particles for trapping light.

    PubMed

    Tang, Yongan; Vlahovic, Branislav

    2013-02-07

    We study metallic nano-particles for light trapping by investigating the optical absorption efficiency of the hydrogenated amorphous silicon thin film with and without metallic nano-particles on its top. The size and shape of these nano-particles are investigated as to their roles of light trapping: scattering light to the absorption medium and converting light to surface plasmons. The optical absorption enhancement in the red light region (e.g., 650nm) due to the light trapping of the metallic nano-particles is observed when a layer of metallic nano-particle array has certain structures. The investigation of the light with incident angles shows the importance of the coupling efficiency of light to surface plasmons in the metallic nano-particle light trapping. PACS: 73.20.Mf, 42.25.s, 88.40.hj.

  8. Enhancement of photo-response via surface plasmon resonance induced by Ag nano-particles embedded in ZnO

    NASA Astrophysics Data System (ADS)

    Li, Gaoming; Zhang, Jingwen; Chen, Guangde; Ye, Honggang; Duan, Xiangyang; Hou, Xun

    2016-09-01

    Surface plasmon resonance can be exploited to improve the performance of the photodetectors. However, it may cause the increase of dark current as a side effect. The enhancement of responsivity is highly dependent on the device structure involving SPR and the situations of the metal nano-particles. In this paper, we reported the responsivity enhancement of the ZnO UV detectors with SPR based on a structure in which Ag nano-particles are embedded in ZnO film, without the apparent increase of dark current. We found that the characteristic wavelength for SPR absorption is 380 nm, well predicted by Mie theory. And the spectral responsivity peak value increases from 472 mA/W to 10.522 A/W, by 22.3 times. The good matching between enhancement spectra and SPR absorption spectra confirms that the responsivity enhancement is resulted from SPR. Our results are of great importance in improving the photodetectors based on SPR effects, which may be widely used in light detection.

  9. Advancing Sustainable Catalysis with Magnetite Surface ...

    EPA Pesticide Factsheets

    This article surveys the recent developments in the synthesis, surface modification, and synthetic applications of magnetitenanoparticles. The emergence of iron(II,III) oxide (triiron tetraoxide or magnetite; Fe3O4, or FeO•Fe2O3) nanoparticles as a sustainable support in heterogeneous catalysis is highlighted. Use of an oxide of earth-abundant iron for various applications in catalysis and environmental remediation.

  10. Selective detection and estimation of C-reactive protein in serum using surface-functionalized gold nano-particles.

    PubMed

    Raj, Vidya; Sreenivasan, K

    2010-03-10

    A new method for the detection of C-reactive protein (CRP) in serum using functionalized gold nano-particles (GNP) is reported. The affinity towards CRP is imparted to GNP by tethering O-phosphorylethanolamine (PEA) onto their surface. GNP and modified GNP were characterized using TEM, particle size analysis, zeta potential measurements, absorption spectroscopy and FT-IR techniques. The event of binding of CRP onto the PEA-GNP is followed by visibly observable colour change. We observed a red shift as well as a decrease in absorption in the plasmon peak of the modified GNP with the concentration of CRP. When the concentration of CRP exceeded 450 ng mL(-1), particles were aggregated and the solution became turbid. The method exhibited a linear range for CRP from 50 to 450 ng mL(-1) with a detection limit of 50 ng mL(-1). The colour change and the variation in absorption of the GNP were highly specific to CRP even in the presence of albumin. We estimated CRP in blood serum collected from patients and the results obtained compared well with the estimation using the technique of nephelometry based on the antibody-antigen interaction.

  11. Gold surface supported spherical liposome-gold nano-particle nano-composite for label free DNA sensing.

    PubMed

    Bhuvana, M; Narayanan, J Shankara; Dharuman, V; Teng, W; Hahn, J H; Jayakumar, K

    2013-03-15

    Immobilization of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposome-gold nano-particle (DOPE-AuNP) nano-composite covalently on 3-mercaptopropionic acid (MPA) on gold surface is demonstrated for the first time for electrochemical label free DNA sensing. Spherical nature of the DOPE on the MPA monolayer is confirmed by the appearance of sigmoidal voltammetric profile, characteristic behavior of linear diffusion, for the MPA-DOPE in presence of [Fe(CN)(6)](3-/4-) and [Ru(NH(3))(6)](3+) redox probes. The DOPE liposome vesicle fusion is prevented by electroless deposition of AuNP on the hydrophilic amine head groups of the DOPE. Immobilization of single stranded DNA (ssDNA) is made via simple gold-thiol linkage for DNA hybridization sensing in the presence of [Fe(CN)(6)](3-/4-). The sensor discriminates the hybridized (complementary target hybridized), un-hybridized (non-complementary target hybridized) and single base mismatch target hybridized surfaces sensitively and selectively without signal amplification. The lowest target DNA concentration detected is 0.1×10(-12)M. Cyclic voltammetry (CV), electrochemical impedance (EIS), differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) techniques are used for DNA sensing on DOPE-AuNP nano-composite. Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE, AuNP and ssDNA. The results indicate the presence of an intact and well defined spherical DOPE-AuNP nano-composite on the gold surface. The method could be applied for fabrication of the surface based liposome-AuNP-DNA composite for cell transfection studies at reduced reagents and costs.

  12. Layer by Layer, Nano-particle "Only" Surface Modification of Filtration Membranes

    NASA Astrophysics Data System (ADS)

    Escobar-Ferrand, Luis

    Layer by Layer (LbL) deposition using primarily inorganic silica nanoparticles is employed for the modification of polymeric micro and ultrafiltration (MF/UF) membranes to produce thin film composites (TFC) with potential nanofiltration (NF) and reverse osmosis (RO) capabilities.. A variety of porous substrate membranes with different membrane surface characteristics are employed, but exhibiting in common that wicking of water does not readily occur into the pore structure, including polycarbonate track etched (PCTE), polyethersulfone (PES) and sulfonated PES (SPEES) MF/UF membranes. Both spherical (cationic/anionic) and eccentric elongated (anionic) silica nanoparticles are deposited using conditions similar to those reported by Lee et al. Appropriate selection of the pH's for anionic and cationic particle deposition enables the construction of nanoparticle only layers 100--1200 nm in thickness atop the original membrane substrates. The surface layer thickness varies monotonically with the number of bilayers (anionic/cationic deposition cycles) as expected. The deposition process is optimized to eliminate drying induced cracking and to improve mechanical durability via thickness control and post-deposition hydro-thermal treatment. The hydrodynamic permeability of these TFC membranes is measured to evaluate their performance under typical NF operating conditions using dead-end permeation experiments and their performance compared quantitatively with realistic hydrodynamic models, with favorable results. For track etched polycarbonate MF substrates, surface modification causes a permeability reduction of approximately two orders of magnitude with respect to the bare substrates, to values comparable to those for typical commercial NF membranes. Good quantitative agreement with hydrodynamic models with no adjustable parameters was also established for this case, providing indirect confirmation that the LbL deposited surface layers are largely defect (crack) free

  13. Surface enhanced Raman scattering of monolayer MX2 with metallic nano particles

    PubMed Central

    Zhang, Duan; Wu, Ye-Cun; Yang, Mei; Liu, Xiao; Coileáin, Cormac Ó; Abid, Mourad; Abid, Mohamed; Wang, Jing-Jing; Shvets, Igor; Xu, Hongjun; Chun, Byong Sun; Liu, Huajun; Wu, Han-Chun

    2016-01-01

    Monolayer transition metal dichalcogenides MX2 (M = Mo, W; X = S) exhibit remarkable electronic and optical properties, making them candidates for application within flexible nano-optoelectronics. The ability to achieve a high optical signal, while quantitatively monitoring strain in real-time is the key requirement for applications in flexible sensing and photonics devices. Surface-enhanced Raman scattering (SERS) allows us to achieve both simultaneously. However, the SERS depends crucially on the size and shape of the metallic nanoparticles (NPs), which have a large impact on its detection sensitivity. Here, we investigated the SERS of monolayer MX2, with particular attention paid to the effect of the distribution of the metallic NPs. We show that the SERS depends crucially on the distribution of the metallic NPs and also the phonon mode of the MX2. Moreover, strong coupling between MX2 and metallic NPs, through surface plasmon excitation, results in splitting of the and modes and an additional peak becomes apparent. For a WS2-Ag system the intensity of the additional peak increases exponentially with local strain, which opens another interesting window to quantitatively measure the local strain using SERS. Our experimental study may be useful for the application of monolayer MX2 in flexible nano-optoelectronics. PMID:27457808

  14. Andromede project: Surface analysis and modification with probes from hydrogen to nano-particles in the MeV energy range

    NASA Astrophysics Data System (ADS)

    Eller, Michael J.; Cottereau, Evelyne; Rasser, Bernard; Verzeroli, Elodie; Agnus, Benoit; Gaubert, Gabriel; Donzel, Xavier; Delobbe, Anne; Della-Negra, Serge

    2015-12-01

    The Andromede project is the center of a multi-disciplinary team which will build a new instrument for surface modification and analysis using the impact of probes from hydrogen to nano-particles (Au400+4) in the MeV range. For this new instrument a series of atomic, polyatomic, molecular and nano-particle ion beams will be delivered using two ion sources in tandem, a liquid metal ion source and an electron cyclotron resonance source. The delivered ion beams will be accelerated to high energy with a 4 MeV van de Graaff type accelerator. By using a suite of probes in the MeV energy range, ion beam analysis techniques, MeV atomic and cluster secondary ion mass spectrometry can all be performed in one location. A key feature of the instrument is its ability to produce an intense beam for injection into the accelerator. The commissioning of the two sources shows that intense beams from atomic ions to nano-particles can be delivered for subsequent acceleration. The calculations and measurements for the two sources are presented.

  15. Silica nano-particle super-hydrophobic surfaces: the effects of surface morphology and trapped air pockets on hydrodynamic drainage forces.

    PubMed

    Chan, Derek Y C; Uddin, Md Hemayet; Cho, Kwun L; Liaw, Irving I; Lamb, Robert N; Stevens, Geoffrey W; Grieser, Franz; Dagastine, Raymond R

    2009-01-01

    We used atomic force microscopy to study dynamic forces between a rigid silica sphere (radius approximately 45 microm) and a silica nano-particle super-hydrophobic surface (SNP-SHS) in aqueous electrolyte, in the presence and absence of surfactant. Characterization of the SNP-SHS surface in air showed a surface roughness of up to two microns. When in contact with an aqueous phase, the SNP-SHS traps large, soft and stable air pockets in the surface interstices. The inherent roughness of the SNP-SHS together with the trapped air pockets are responsible for the superior hydrophobic properties of SNP-SHS such as high equilibrium contact angle (> 140 degrees) of water sessile drops on these surfaces and low hydrodynamic friction as observed in force measurements. We also observed that added surfactants adsorbed at the surface of air pockets magnified hydrodynamic interactions involving the SNP-SHS. The dynamic forces between the same silica sphere and a laterally smooth mica surface showed that the fitted Navier slip lengths using the Reynolds lubrication model were an order of magnitude larger than the length scale of the sphere surface roughness. The surface roughness and the lateral heterogeneity of the SNP-SHS hindered attempts to characterize the dynamic response using the Reynolds lubrication model even when augmented with a Navier slip boundary.

  16. PVP stabilized Pt nano particles catalyzed de-oxygenation of phenoxazine group by hydrazine in physiological buffer media: surfactant competes with reactants for the same surface sites.

    PubMed

    Das, Ranendu Sekhar; Singh, Bula; Banerjee, Rupendranath; Mukhopadhyay, Subrata

    2013-03-21

    PVP capped platinum nano particles (PNP) of 5 nm diameter were prepared and characterized as homogeneous and of spherical nature. At physiological pH range (6.0-8.0), these PNP catalyze the deoxygenation of phenoxazine group containing resazurin (1) by hydrazine. The observed rate constants (k(o)), increase linearly with [PNP] at constant [1] and [Hydrazine]; but first increase and then after reaching a maximum it decrease with increase in [1] as well as in [Hydrazine]. The k(o) values increase linearly with 1/[H(+)] indicating N(2)H(4) as the reducing species that generates from the PNP assisted deprotonation of N(2)H(5)(+). The kinetic observations suggest Langmuir-Hinshelwood type surface reaction mechanism where both 1 and hydrazine are adsorbed on nano particles surface and compete for the same sites. Interestingly, the surfactant molecules, polyvinylpyrrolidone (PVP), though do not take part into reduction reaction but having same type of functional groups as reactants, competes with them for the same surface sites. Adsorption on PNP with same type of functional group is further supported by the FTIR spectra of Pt-PVP and Pt-1. Thus on increasing [PVP], k(o) decreases linearly and only when [PVP] is held constant, the plot of k(o) vs. [PNP] passes through the origin indicating the insignificance of uncatalyzed reaction. The plot of ln k(o) vs. [1] or [Hydrazine] shows two different linear zones with different exponent values with respect to [1] and [Hydrazine]. This indicates that along with the complex heterogeneous surface adsorption processes, the mutual interactions between the reactants are also changing with the relative concentrations of reactants or, in general, with the molar ratio ([Hydrazine]/[1]).

  17. The Measurement of Surface Rheological and Surface Adhesive Properties of a PDMS Rubber using Micro- and Nano-Particle Embedment

    NASA Astrophysics Data System (ADS)

    Hutcheson, Stephen; McKenna, Gregory

    2009-03-01

    In previous work, we used particle embedment data to determine the rheological response of the surfaces of a polystyrene film, a phase separated copolymer and a commercially available polydimethylsiloxane (PDMS) rubber through the application of a viscoelastic contact mechanics model. The goal of the current research is to build off this analysis and use micro- and nano-sphere embedment experiments to probe the surface rheological behavior of PDMS in the rubbery state. The work includes measurements made with different particle diameters and chemistries. An atomic force microscope (AFM) is used to measure the embedment depth as nanoparticles are pulled into the surface by the thermodynamic work of adhesion. Present results show that silica probes of different sizes (500 nm and 300 nm) give different results for the surface adhesion properties and the surface rheological properties determined from the particle embedment data and at scales much larger than the nanometer size scale where one might expect such deviations. Possible water entrapment and effects of particle surface composition on the results will be discussed.

  18. Advancing Sustainable Catalysis with Magnetite Surface Modification and Synthetic Applications

    EPA Science Inventory

    This article surveys the recent developments in the synthesis, surface modification, and synthetic applications of magnetitenanoparticles. The emergence of iron(II,III) oxide (triiron tetraoxide or magnetite; Fe3O4, or FeO•Fe2O3) nanoparticles as a sustainable support in heteroge...

  19. Surface reactions kinetics between nanocrystalline magnetite and uranyl.

    PubMed

    Missana, Tiziana; Maffiotte, César; García-Gutiérrez, Miguel

    2003-05-01

    Magnetite is the most important end member of iron corrosion products under reducing environment, which is the condition expected in a deep geological high level radioactive waste disposal. Nanocrystalline magnetite was synthesized in the laboratory and its physicochemical properties were analyzed in detail. The kinetics of the adsorption of U(VI) and the kinetics of the actinide reduction to a lower oxidation state, in presence of the oxide, were studied by means of batch sorption techniques and X-ray photoelectron spectroscopy (XPS) analysis. The results showed that the uranium sorption and reduction processes on the magnetite surface have very fast kinetics (hours), the reduction process being triggered by sorption. XPS measurements showed that the speciation of uranium at the surface does not show significant changes with time (from 1 day to 3 months), as well as the quantity of uranium detected at the surface. The surface speciation depended on the initial pH of the contact solution. Considering that the Eh of equilibrium between magnetite and the solution, under our experimental conditions, is slightly positive (50-100 mV), the uranium reduction would also be thermodynamically possible within the liquid phase. However, the kinetics of reduction in the liquid occur at a much slower rate which, in turn, has to depend on the attainment of the magnetite/solution equilibrium. The decrease of uranium in solution, observed after the uranyl adsorption stage, and particularly at acidic pH, is most probably due to the precipitation of U(IV) formed in the solution.

  20. Oxygen vacancy induced surface stabilization: (110) terminated magnetite

    NASA Astrophysics Data System (ADS)

    Walls, B.; Lübben, O.; Palotás, K.; Fleischer, K.; Walshe, K.; Shvets, I. V.

    2016-10-01

    Scanning tunneling microscopy (STM) measurements of the (110) surface of magnetite showed the coexistence of two reconstructions: the known (1 ×3 ) row reconstruction and a surprising atomic structure of high complexity which occupies a small fraction of the surface. Oxygen vacancies on the Fe3O4 (110) B-terminated surface have previously been determined to be the most energetically favorable surface termination of those considered [Li et al., Surf. Sci. 601, 876 (2007), 10.1016/j.susc.2006.10.037]. However, this study only investigated oxygen vacancies which were threefold coordinated. Here, first principles calculations indicate that twofold coordinated oxygen represents the most energetically stable oxygen vacancy on the B-terminated (110) surface of magnetite. STM simulations reveal that the structure that occupies a small fraction of the surface corresponds to this energetically favorable B-terminated Fe3O4 (110) surface. The oxygen vacancies form an ordered array: Along the [1 ¯10 ] direction, every second twofold coordinated oxygen atom is vacant, and vacancies are separated by 6 Å. In adjacent twofold coordinated oxygen rows, the vacancies are shifted in the [1 ¯10 ] direction by 3 Å. Density functional theory calculations of the spin density distributions indicate that surface and subsurface octahedrally coordinated iron atoms are charge ordered. The charge ordering and existence of oxygen vacancies act to reduce the surface charge. However, other polarity compensation mechanisms may be at play to stabilize the surface.

  1. Gold nano-particles fixed on glass

    NASA Astrophysics Data System (ADS)

    Worsch, Christian; Wisniewski, Wolfgang; Kracker, Michael; Rüssel, Christian

    2012-09-01

    A simple process for producing wear resistant gold nano-particle coatings on transparent substrates is proposed. Soda-lime-silica glasses were sputtered with gold and subsequently coated with SiO2 using a combustion chemical vapor deposition technique. Some samples were first coated with silica, sputtered with gold and then coated with a second layer of silica. The samples were annealed for 20 min at either 550 or 600 °C. This resulted in the formation of round, well separated gold nano-particles with sizes from 15 to 200 nm. The color of the coated glass was equivalent to that of gold-ruby glasses. Silica/gold/silica coatings annealed at 600 °C for 20 min were strongly adherent and scratch resistant. X-ray diffraction and electron backscatter diffraction (EBSD) were used to describe the crystal orientations of the embedded particles. The gold particles are preferably oriented with their (1 1 1) planes perpendicular to the surface.

  2. A molecular dynamics investigation of surface reconstruction on magnetite (001)

    NASA Astrophysics Data System (ADS)

    Rustad, J. R.; Wasserman, E.; Felmy, A. R.

    1999-07-01

    Molecular dynamics calculations using analytical potential functions with polarizable oxygen ions have been used to identify a novel mode of reconstruction on the half-occupied tetrahedral layer termination of the magnetite (Fe 3O 4) (001) surface. In the proposed reconstruction, the twofold coordinated iron ion in the top monolayer rotates downward to occupy a vacant half-octahedral site in the plane of the second-layer iron ions. At the same time, half of the tetrahedral iron ions in the third iron layer are pushed upward to occupy an adjacent octahedral vacancy at the level of the second-layer iron ions. The other half of the third-layer iron ions remain roughly in their original positions. The proposed reconstruction is consistent with recent low-energy electron diffraction and X-ray photoelectron spectroscopy results. It also provides a compelling interpretation for the arrangement of atoms suggested by high-resolution scanning-tunneling microscopy studies.

  3. Oleic acid coated magnetic nano-particles: Synthesis and characterizations

    SciTech Connect

    Panda, Biswajit Goyal, P. S.

    2015-06-24

    Magnetic nano particles of Fe{sub 3}O{sub 4} coated with oleic acid were synthesized using wet chemical route, which involved co-precipitation of Fe{sup 2+} and Fe{sup 3+} ions. The nano particles were characterized using XRD, TEM, FTIR, TGA and VSM. X-ray diffraction studies showed that nano particles consist of single phase Fe{sub 3}O{sub 4} having inverse spinel structure. The particle size obtained from width of Bragg peak is about 12.6 nm. TEM analysis showed that sizes of nano particles are in range of 6 to 17 nm with a dominant population at 12 - 14 nm. FTIR and TGA analysis showed that -COOH group of oleic acid is bound to the surface of Fe{sub 3}O{sub 4} particles and one has to heat the sample to 278° C to remove the attached molecule from the surface. Further it was seen that Fe{sub 3}O{sub 4} particles exhibit super paramagnetism with a magnetization of about 53 emu/ gm.

  4. Effect of micro/nano-particles in cavitation erosion.

    PubMed

    Li, Y J; Chen, H S; Chen, D R; Wang, J D

    2009-02-01

    The tests in de-ionized water with micro/nano CeO2 particles are carried out to study the effect of the micro/nano particles in inception of cavitation erosion. The existence of micro/nano particles is found to be the requisite factor and the degree of cavitation erosion is related to the sizes of the particles. Particles in the micro/nano scale may act as the transporters of micro bubbles to keep or get close to the solid surface together and the pressure fluctuation induced by the surface roughness causes the collapse of bubbles and erosion of the surface. Discrete phase models are employed to simulation the moving tracks of the particles. The sizes of the particles affect their capabilities of keeping and getting close to the surface. The effect of the particles of a certain size in cavitation erosion is determined by the combinational action of the two.

  5. Nickel nano-particle modified nitrogen-doped amorphous hydrogenated diamond-like carbon film for glucose sensing

    SciTech Connect

    Zeng, Aiping; Jin, Chunyan; Cho, Sang-Jin; Seo, Hyun Ook; Kim, Young Dok; Lim, Dong Chan; Kim, Doo Hwan; Hong, Byungyou; Boo, Jin-Hyo

    2012-10-15

    Electrochemical method has been employed in this work to modify nitrogen-doped hydrogen amorphous diamond-like carbon (N-DLC) film to fabricate nickel nano-particle-modified N-DLC electrodes. The electrochemical behavior of the nickel nano-particle-modified N-DLC electrodes has been characterized at the presence of glucose in electrolyte. Meanwhile, the N-DLC film structure and the morphology of metal nano-particles on the N-DLC surface have been investigated using micro-Raman spectroscopy and atomic force microscopy. The nickel nano-particle-modified N-DLC electrode exhibits a high catalytic activity and low background current. This result shows that the nickel nano-particle deposition on N-DLC surface could be a promising method to fabricate novel electrode materials for glucose sensing.

  6. Nano-Particles in Cosmic Plasma Environments

    SciTech Connect

    Mann, Ingrid

    2008-09-07

    Astronomical observations and in-situ measurements point to the existence of cosmic nano-particles, but in most cases their material composition and structure are not known. Nano-dust interacts differently than larger dust with the cosmic radiation and plasma environment. Its dynamics and behavior upon collision is not well studied.

  7. Synthesis and characterization of struvite nano particles

    NASA Astrophysics Data System (ADS)

    Rathod, K. R.; Jogiya, B. V.; Chauhan, C. K.; Joshi, M. J.

    2015-06-01

    Struvite, Ammonium Magnesium Phosphate Hexahydrate [(AMPH) - (NH4)MgPO4.6(H2O)], is one of the fascinating inorganic phosphate minerals. Struvite is one of the components of the urinary stones. Struvite occurs as crystallites in urine and grows as a type of kidney stone. In this study, struvite nano particles were synthesized by wet chemical technique. The aqueous solutions containing dissolved Mg(CH3COO)2.4H2O and (NH4)H2PO4 mixed at the Mg/P molar ratio of 1.00. The synthesized struvite nano particles were characterized by XRD, FT-IR, Thermal Analysis and TEM. From XRD, crystal structure of the nano particle was found to be orthorhombic and crystalline size was found to be within 11 to 26 nm. The FT-IR spectrum for the struvite nano particles confirmed the presence of a water molecule and metal-oxygen stretching vibration, O-H stretching and bending, N-H bending and stretching, P-O bending and stretching vibrations. The Thermal Analysis was carried out from room temperature to 900°C. From TEM analysis, particle size was 23 to 30 nm. All the results were compared with bulk struvite.

  8. Dynamics of magnetic nano-particle assembly

    NASA Astrophysics Data System (ADS)

    Kondratyev, V. N.

    2010-11-01

    Ferromagnetically coupled nano-particle assembly is analyzed accounting for inter- and intra- particle electronic structures within the randomly jumping interacting moments model including quantum fluctuations due to the discrete levels and disorder. At the magnetic jump anomalies caused by quantization the magnetic state equation and phase diagram are found to indicate an existence of spinodal regions and critical points. Arrays of magnetized nano-particles with multiple magnetic response anomalies are predicted to display some specific features. In a case of weak coupling such arrays exhibit the well-separated instability regions surrounding the anomaly positions. With increasing coupling we observe further structure modification, plausibly, of bifurcation type. At strong coupling the dynamical instability region become wide while the stable regime arises as a narrow islands at small disorders. It is shown that exploring correlations of magnetic noise amplitudes represents convenient analytical tool for quantitative definition, description and study of supermagnetism, as well as self-organized criticality.

  9. Adsorption of alkenyl succinic anhydride from solutions in carbon tetrachloride on a fine magnetite surface

    NASA Astrophysics Data System (ADS)

    Balmasova, O. V.; Ramazanova, A. G.; Korolev, V. V.

    2016-06-01

    The adsorption of alkenyl succinic anhydride from a solution in carbon tetrachloride on a fine magnetite surface at a temperature of 298.15 K is studied using fine magnetite, which forms the basis of magnetic fluids, as the adsorbent. An adsorption isotherm is recorded and interpreted in terms of the theory of the volume filling of micropores (TVFM). Adsorption process parameters are calculated on the basis of the isotherm. It is shown that at low equilibrium concentrations, the experimental adsorption isotherm is linear in the TVFM equation coordinates.

  10. Cell surface receptor interactions of C 27-steroid hormone ecdysterone immobilized on nanodispersed magnetite

    NASA Astrophysics Data System (ADS)

    Mykhaylyk, O. M.; Kotzuruba, A. V.; Buchanevich, O. M.; Gula, N. M.; Bakai, E. A.

    1999-04-01

    Concurrent binding of ecdysterone immobilized on the nanodispersed magnetite with intact rat cells in the presence of free ecdysterone was investigated. The results imply the existence of high affinity ecdysterone-specific binding sites on the surface of liver and spleen macrophages, thymus and spleen lymphocytes, erythrocytes and hepatocytes. Membrane effects may be involved in the signal transduction mechanisms activated by ecdysterone.

  11. Evaluation of minimum quantity lubrication grinding with nano-particles and recent related patents.

    PubMed

    Li, Changhe; Wang, Sheng; Zhang, Qiang; Jia, Dongzhou

    2013-06-01

    In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a supply system for the grinding fluid in nano-particle jet MQL, which produced MQL lubricant by adding solid nano-particles in degradable grinding fluid. The MQL supply device turns the lubricant to the pulse drops with fixed pressure, unchanged pulse frequency and the same drop diameter. The drops will be produced and injected in the grinding zone in the form of jet flow under high pressure gas and air seal. As people become increasingly demanding on our environment, minimum quantity lubrication has been widely used in the grinding and processing. Yet, it presents the defect of insufficient cooling performance, which confines its development. To improve the heat transfer efficiency of MQL, nano-particles of a certain mass fraction can be added in the minimum quantity of lubricant oil, which concomitantly will improve the lubrication effects in the processing. In this study, the grinding experiment corroborated the effect of nano-particles in surface grinding. In addition, compared with other forms of lubrication, the results presented that the grinding force, the friction coefficient and specific grinding energy of MQL grinding have been significantly weakened, while G ratio greatly rose. These are attributed to the friction oil-film with excellent anti-friction and anti-wear performance, which is generated nano-particles at the wheel/workpiece interface. In this research, the cooling performance of nano-particle jet MQL was analyzed. Based on tests and experiments, the surface temperature was assayed from different methods, including flood lubricating oil, dry grinding, MQL grinding and nano-particle jet MQL grinding. Because of the outstanding heat transfer

  12. Antibacterial characteristics of heated scallop-shell nano-particles.

    PubMed

    Watanabe, Takashi; Fujimoto, Riku; Sawai, Jun; Kikuchi, Mikio; Yahata, Shinya; Satoh, Susumu

    2014-01-01

    Heated scallop-shell (HSS) nano-particles, prepared using a wet grinding mill, and microparticles were examined for their antibacterial activity against vegetative bacterial cells and spores. The median diameters of the nano-particles and micro-particles were approximately 20 nm and 30 µm, respectively. The antibacterial activity of HSS against Escherichia coli increased with an increase in concentration, regardless of particle size; however, the antibacterial activity of the nano-particles was much higher than that of micro-particles. The sporicidal activity of the nano-particles was also much higher than that of micro-particles, with HSS nano-particles able to kill Bacillus subtilis spores. A reduction of more than three orders of magnitude for B. subtilis spores was confirmed following a 30 min treatment at 5 mg/ml and 60℃, showing that the combination of HSS nano-particle treatment with mild heating was particularly effective for controlling bacterial spores.

  13. Thermoelectric properties of SrTiO3 nano-particles dispersed indium selenide bulk composites

    NASA Astrophysics Data System (ADS)

    Lee, Min Ho; Rhyee, Jong-Soo; Vaseem, Mohammad; Hahn, Yoon-Bong; Park, Su-Dong; Jin Kim, Hee; Kim, Sung-Jin; Lee, Hyeung Jin; Kim, Chilsung

    2013-06-01

    We investigated the thermoelectric properties of the InSe, InSe/In4Se3 composite, and SrTiO3 (STO) nano-particles dispersed InSe/In4Se3 bulk composites. The electrical conductivity of the InSe/In4Se3 composite with self-assembled phase separation is significantly increased compared with those of InSe and In4Se3-δ implying the enhancement of surface conductivity between grain boundaries. The thermal conductivity of InSe/In4Se3 composite is decreased compared to those of InSe. When the STO nano-particle dispersion was employed in the InSe/In4Se3 composite, a coherent interface was observed between nano-particle precipitates and the InSe bulk matrix with a reduction of the thermal conductivity.

  14. PLA micro- and nano-particles.

    PubMed

    Lee, Byung Kook; Yun, Yeonhee; Park, Kinam

    2016-12-15

    Poly(d,l-lactic acid) (PLA) has been widely used for various biomedical applications for its biodegradable, biocompatible, and nontoxic properties. Various methods, such as emulsion, salting out, and precipitation, have been used to make better PLA micro- and nano-particle formulations. They are widely used as controlled drug delivery systems of therapeutic molecules, including proteins, genes, vaccines, and anticancer drugs. Even though PLA-based particles have challenges to overcome, such as low drug loading capacity, low encapsulation efficiency, and terminal sterilization, continuous innovations in particulate formulations will lead to development of clinically useful formulations.

  15. Impact of surface coated magnetite used in magnetic drug delivery system on immune response

    NASA Astrophysics Data System (ADS)

    Oaku, Yoshihiro; Tamada, Junya; Mishima, Fumihito; Akiyama, Yoko; Osako, Mariana Kiomy; Koriyama, Hiroshi; Nakagami, Hironori; Nishijima, Shigehiro

    2015-05-01

    Magnetic drug delivery system (MDDS) is a technique to effectively accumulate drugs, which are combined with ferromagnetic particles, into the affected area using magnetic force control. This study intends to apply MDDS for immunotherapy by enhancing immune responses by a surface treatment of a ferromagnetic particle. The objective of this study is to give the adjuvant effect to a ferromagnetic particle by the surface treatment with alum, which is known as one of the common adjuvants that activates inflammasome pathway. First, magnetite was prepared as a ferromagnetic particle and coated with alum. Alum-coated magnetite increased the expression of caspase-1, which is an activated indicator of inflammasome, in the culture of human monocyte cell (THP-1 cell). To evaluate the potential of the surface coated particles, the particles were subcutaneously injected to mice with a peptide vaccine. As a result, the antibody titer was increased by the surface coated particles as assessed by ELISA. Although a magnetic force has not yet applied in this study, the administration experiment to mice using magnetic force control is our next step. In conclusion, we modified the immune response to magnetite by coating the surface with alum. This can lead to a clinical application for vaccine therapy in future.

  16. Galvanostatic interruption of lithium insertion into magnetite: Evidence of surface layer formation

    DOE PAGES

    Nicholas W. Brady; Takeuchi, Esther S.; Knehr, K. W.; ...

    2016-04-24

    Magnetite is a known lithium intercalation material, and the loss of active, nanocrystalline magnetite can be inferred from the open-circuit potential relaxation. Specifically, for current interruption after relatively small amounts of lithium insertion, the potential first increases and then decreases, and the decrease is hypothesized to be due to a formation of a surface layer, which increases the solid-state lithium concentration in the remaining active material. Comparisons of simulation to experiment suggest that the reactions with the electrolyte result in the formation of a thin layer of electrochemically inactive material, which is best described by a nucleation and growth mechanism.more » Simulations are consistent with experimental results observed for 6, 8 and 32-nm crystals. As a result, simulations capture the experimental differences in lithiation behavior between the first and second cycles.« less

  17. Galvanostatic interruption of lithium insertion into magnetite: Evidence of surface layer formation

    SciTech Connect

    Nicholas W. Brady; Takeuchi, Esther S.; Knehr, K. W.; Cama, Christina A.; Lininger, Christianna N.; Lin, Zhou; Marschilok, Amy C.; Takeuchi, Kenneth J.; West, Alan C.

    2016-04-24

    Magnetite is a known lithium intercalation material, and the loss of active, nanocrystalline magnetite can be inferred from the open-circuit potential relaxation. Specifically, for current interruption after relatively small amounts of lithium insertion, the potential first increases and then decreases, and the decrease is hypothesized to be due to a formation of a surface layer, which increases the solid-state lithium concentration in the remaining active material. Comparisons of simulation to experiment suggest that the reactions with the electrolyte result in the formation of a thin layer of electrochemically inactive material, which is best described by a nucleation and growth mechanism. Simulations are consistent with experimental results observed for 6, 8 and 32-nm crystals. As a result, simulations capture the experimental differences in lithiation behavior between the first and second cycles.

  18. Galvanostatic interruption of lithium insertion into magnetite: Evidence of surface layer formation

    NASA Astrophysics Data System (ADS)

    Brady, Nicholas W.; Knehr, K. W.; Cama, Christina A.; Lininger, Christianna N.; Lin, Zhou; Marschilok, Amy C.; Takeuchi, Kenneth J.; Takeuchi, Esther S.; West, Alan C.

    2016-07-01

    Magnetite is a known lithium intercalation material, and the loss of active, nanocrystalline magnetite can be inferred from the open-circuit potential relaxation. Specifically, for current interruption after relatively small amounts of lithium insertion, the potential first increases and then decreases, and the decrease is hypothesized to be due to a formation of a surface layer, which increases the solid-state lithium concentration in the remaining active material. Comparisons of simulation to experiment suggest that the reactions with the electrolyte result in the formation of a thin layer of electrochemically inactive material, which is best described by a nucleation and growth mechanism. Simulations are consistent with experimental results observed for 6, 8 and 32-nm crystals. Furthermore, simulations capture the experimental differences in lithiation behavior between the first and second cycles.

  19. Genotoxicity and inflammatory investigation in mice treated with magnetite nanoparticles surface coated with polyaspartic acid

    NASA Astrophysics Data System (ADS)

    Sadeghiani, N.; Barbosa, L. S.; Silva, L. P.; Azevedo, R. B.; Morais, P. C.; Lacava, Z. G. M.

    2005-03-01

    In this study, some biological tests were carried out with a magnetic fluid (MF) sample based on magnetite nanoparticles (MNPs) surface coated with polyaspartic acid (PAMF). The tests were performed from 1 to 30 days after injection of 50 μL of PAMF in Swiss mice. The PAMF biocompatibility/toxicity was evaluated through cytometry, micronuclei assay, and morphology of several organs. All observed results were time and dose dependent. The data indicate that MNPs surface-treated with polyaspartic acid may be considered as a potential precursor of anticancer drugs.

  20. A micromagnetic investigation of magnetite grains in the form of Platonic polyhedra with surface roughness

    NASA Astrophysics Data System (ADS)

    Williams, W.; Muxworthy, A. R.; Evans, M. E.

    2011-10-01

    Micromagnetic calculations have been carried out for spherical magnetite particles with surface roughness consisting of patterns of conical bumps based on regular (Platonic) convex polyhedra. The purpose was to examine the effect of surface irregularities while avoiding overall shape anisotropy, which generally plays a dominant role in determining hysteresis properties. We considered three morphologies based on the tetrahedron (4 apices), the icosahedron (12 apices), and the dodecahedron (20 apices). Grains of three sizes were considered: 30 nm (single-domain, SD), 90 nm (on the single-domain/pseudo-single-domain boundary, SD/PSD), and 120 nm (stable pseudo-single-domain, PSD). We find that the morphologies investigated have very little effect on the hysteresis parameters of SD and marginal SD/PSD grains. However, in the PSD grains, coercivity increases significantly as bump amplitude increases from 0.1 to 0.9. This lends support to the long-standing notion that surface protuberances on larger grains are a possible source of paleomagnetically significant stable remanence, although the very high coercivities (on the order of 100 mT) observed in some rocks cannot be achieved. Classical Stoner-Wohlfarth shape anisotropy remains the only explanation for such ultra-stable remanence in magnetite-bearing rocks. This is confirmed by a specific example of a model "skeletal" grain consisting of three orthogonal parallelepipeds.

  1. Mechanisms for nano particle removal in brush scrubber cleaning

    NASA Astrophysics Data System (ADS)

    Huang, Yating; Guo, Dan; Lu, Xinchun; Luo, Jianbin

    2011-01-01

    A model describing the nano particle (<100 nm) removal behavior in brush scrubber cleaning is presented based on experiment results and theoretical analysis. The forces on the particles in different situations are analyzed and discussed. The adhesion forces of the van der Waals force, the electrostatic force, the brush load and the static friction between the particle and the wafer are calculated. The contact elastic force, hydrodynamic drag force and friction between the brush and the particle are considered as removal forces and are evaluated. The porous structure and roughness surface of brush material are considered in the hydrodynamic model to describe the brush deformation and the flow field in the cleaning process. The porous structure will result in decrease of hydrodynamic drag force. There are four situations of the particles relative to the brush roughness asperities for which the forces on the particle are different. When the particle is in contact with a brush asperity or on the wafer surface and in a semi-infinite fluid flow field, the particle may be removed by hydrodynamic force and elastic force in the presence of surfactant. When the particle is embedded in the brush asperity, the remove will realized when the friction caused by adhesion between the brush and the particle overcome the adhesion force between particle and wafer surface. The removed particles will be in the flow field or adhered on the brush surface and may redeposit on the wafer surface.

  2. Engineered nano particles: Nature, behavior, and effect on the environment.

    PubMed

    Goswami, Linee; Kim, Ki-Hyun; Deep, Akash; Das, Pallabi; Bhattacharya, Satya Sundar; Kumar, Sandeep; Adelodun, Adedeji A

    2017-03-13

    Increased application of engineered nano particles (ENPs) in production of various appliances and consumer items is increasing their presence in the natural environment. Although a wide variety of nano particles (NPs) are ubiquitously dispersed in ecosystems, risk assessment guidelines to describe their ageing, direct exposure, and long-term accumulation characteristics are poorly developed. In this review, we describe what is known about the life cycle of ENPs and their impact on natural systems and examine if there is a cohesive relationship between their transformation processes and bio-accessibility in various food chains. Different environmental stressors influence the fate of these particles in the environment. Composition of solid media, pore size, solution chemistry, mineral composition, presence of natural organic matter, and fluid velocity are some environmental stressors that influence the transformation, transport, and mobility of nano particles. Transformed nano particles can reduce cell viability, growth and morphology, enhance oxidative stress, and damage DNA in living organisms.

  3. Synthesis and characterization of monosodium urate (MSU) nano particles

    NASA Astrophysics Data System (ADS)

    Tank, Nirali S.; Rathod, K. R.; Parekh, B. B.; Parikh, K. D.; Joshi, M. J.

    2016-05-01

    In Gout the deposition of crystals of Monosodium Urate (MSU) in various connective tissues and joints occurs, which is very painful with immflamation. The deposition likely to begin with nano particles form and expected to grow in to micro-paricles and hence it is important to synthesize and characrterize MSU nano-particles. The MSU nano particles were synthesized by wet chemical method using NaOH and uric acid (C5H4N4O3) and then characterized by powder XRD, TEM, FT-IR and thermal analysis. From the powder XRD the triclinic structure was found and 40 nm average particle size was estimated by using Scherrer's formula. From TEM the particle size was found to be in the range of 20 to 60 nm. The FT-IR spectrum for the MSU nano particles confirmed the presence of O-H stretching, N-H stretching, N-H rocking, C = O, C = C Enol or Keto and C = N vibrations. The thermal analysis was carried out from room temperature to 900°C. With comparison to the bulk MSU the thermal stability of MSU nano particles was slightly higher and 1.5 water molecules were found to be associated with MSU nano particles. Present results are compared with the bulk MSU.

  4. U(VI) Sorption and Reduction Kinetics on the Magnetite (111) Surface

    SciTech Connect

    Singer, David M.; Chatman, Shawn M.; Ilton, Eugene S.; Rosso, Kevin M.; Banfield, Jillian F.; Waychunas, Glenn A.

    2012-04-03

    Sorption of contaminants onto mineral surfaces is an important process that can restrict their transport in the environment. In the current study, uranium (U) uptake on magnetite (111) was measured as a function of time and solution composition (pH, [CO3]T, [Ca]) under continuous batch-flow conditions. We observed, in real-time and in situ, adsorption and reduction of U(VI) and subsequent growth of UO2 nanoprecipitates using atomic force microscopy (AFM) and newly developed batch-flow U LIII-edge grazing-incidence X-ray absorption spectroscopy near-edge structure (GI-XANES) spectroscopy. U(VI) reduction occurred with and without CO3 present, and coincided with nucleation and growth of UO2 particles. When Ca and CO3 were both present no U(VI) reduction occurred and the U surface loading was lower. In situ batch-flow AFM data indicated that UO2 particles achieved a maximum height of 4–5 nm after about 8 h of exposure, however, aggregates continued to grow laterally after 8 h reaching up to about 300 nm in diameter. The combination of techniques indicated that U uptake is divided into three-stages; (1) initial adsorption of U(VI), (2) reduction of U(VI) to UO2 nanoprecipitates at surface-specific sites after 2–3 h of exposure, and (3) completion of U(VI) reduction after ~6–8 h. U(VI) reduction also corresponded to detectable increases in Fe released to solution and surface topography changes. Redox reactions are proposed that explicitly couple the reduction of U(VI) to enhanced release of Fe(II) from magnetite. Although counterintuitive, the proposed reaction stoichiometry was shown to be largely consistent with the experimental results. In addition to providing molecular-scale details about U sorption on magnetite, this work also presents novel advances for collecting surface sensitive molecular-scale information in real-time under batch-flow conditions.

  5. Carbon tetrachloride transformation on the surface of nanoscale biogenic magnetite particles.

    PubMed

    McCormick, Michael L; Adriaens, Peter

    2004-02-15

    Iron-reducing conditions in subsurface environments promote dechlorination reactions via both biotic and abiotic pathways, the latter often mediated via biologically activated minerals formed by dissimilatory iron-reducing bacteria (DIRB). Here we report the major products and pathways associated with the abiotic transformation of carbon tetrachloride (CT) by nanoscale biogenic magnetite/maghemite particles produced by the DIRB Geobacter metallireducens. Product formation and free radical/carbene trapping studies indicate that CT transformation occurs via three parallel pathways. The first pathway (hydrogenolysis) results in the formation of chloroform (45-50%) via a trichloromethyl free radical (*CCl3) and possibly a trichloromethyl carbanion (**CCl3-). The second and third pathways involve a dichlorocarbene intermediate (**CCl2), which either hydrolyzes to form CO (approximately 38%) (carbene hydrolysis), or undergoes further reduction to yield methane (8-10%) (carbene reduction). The mechanism of methane formation from **CCl2 is not known, but is speculated to involve a sequence of surface coordinated carbenoid and free radical complexes. The large fraction of relatively benign products formed by the carbene-mediated pathways suggests that magnetite/maghemite particles may have a beneficial application in the remediation of CT contaminated environments.

  6. Investigation on the antibacterial micro-porous titanium with silver nano-particles.

    PubMed

    Dong, Wei; Zhu, Yingchun; Zhang, Jingxian; Lu, Liqiang; Zhao, Chengjian; Qin, Lifeng; Li, Yingbin

    2013-10-01

    Micro-porous titanium is coated with silver nanoparticles by using a simple chemical reduction method that exhibits excellent antibacterial ability. Scanning electron microscopy (SEM) shows that the silver nanoparticles with average sizes of about 100 nm are formed homogeneously on the micro-porous titanium surface. After the micro-porous Ti coated with silver nano particles is treated by heating, the average size of the silver nano particles is slightly increased, but the nano particles are more uniformly dispersed on the surface of the micro-porous titanium. X-ray diffraction (XRD) indicates that those nanoparticles are metallic silver produced on the micro-porous titanium surface. The samples of micro-porous titanium coated with silver nanoparticles inhibit the growth of Escherichia coli. Our results show that the electrical double layer of the samples play an important role in the antibiosis and this study opens a new window for antibacterial mechanism which may be suitable for the other antibacterial metallic materials.

  7. Development of functional nano-particle layer for highly efficient OLED

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Hyun; Kim, Min-Hoi; Choi, Haechul; Choi, Yoonseuk

    2015-12-01

    Organic light emitting diodes (OLEDs) are now widely commercialized in market due to many advantages such as possibility of making thin or flexible devices. Nevertheless there are still several things to obtain the high quality flexible OLEDs, one of the most important issues is the light extraction of the device. It is known that OLEDs have the typical light loss such as the waveguide loss, plasmon absorption loss and internal total reflection. In this paper, we demonstrate the one-step processed light scattering films with aluminum oxide nano-particles and polystyrene matrix composite to achieve highly efficient OLEDs. Optical characteristics and surface roughness of light scattering film was optimized by changing the mixing concentration of Al2O3 nano-particles and investigated with the atomic force microscopy and hazemeter, respectively.

  8. Determination of anionic surface active agents using silica coated magnetite nanoparticles modified with cationic surfactant aggregates.

    PubMed

    Pena-Pereira, Francisco; Duarte, Regina M B O; Trindade, Tito; Duarte, Armando C

    2013-07-19

    The development of a novel methodology for extraction and preconcentration of the most commonly used anionic surface active agents (SAAs), linear alkylbenzene sulfonates (LAS), is presented herein. The present method, based on the use of silica-magnetite nanoparticles modified with cationic surfactant aggregates, was developed for determination of C10-C13 LAS homologues. The proposed methodology allowed quantitative recoveries of C10-C13 LAS homologues by using a reduced amount of magnetic nanoparticles. Limits of detection were in the range 0.8-1.9μgL(-1) for C10-C13 LAS homologues, while the repeatability, expressed as relative standard deviation (RSD), ranged from 2.0 to 3.9% (N=6). Finally, the proposed method was successfully applied to the analysis of a variety of natural water samples.

  9. Thermal performance of heat pipe with suspended nano-particles

    NASA Astrophysics Data System (ADS)

    Shukla, K. N.; Solomon, A. Brusly; Pillai, B. C.; Ruba Singh, B. Jacob; Saravana Kumar, S.

    2012-11-01

    Nanofluids are employed as the working medium for a conventional cylindrical heat pipe. A cylindrical copper heat pipe of 19.5 mm outer diameter and 400 mm length was fabricated and tested with two different working fluids. The working fluids used in this study are DI-water and Nano-particles suspension (mixture of copper nano particle and DI-water). The overall heat transfer coefficient of the heat pipe was calculated based on the lumped thermal resistance network and compared with the heat transfer coefficient of base fluid filled heat pipe. There is a quantitative improvement in the heat transfer coefficient using nano-particles suspension as the working medium. A heat transfer correlation was also developed based on multiple regression least square method and the results were compared with that obtained by the experiment.

  10. Effect of BaTiO3 nano-particles on breakdown performance of propylene carbonate.

    PubMed

    Hou, Yanpan; Zhang, Zicheng; Zhang, Jiande; Liu, Zhuofeng; Song, Zuyin

    2015-05-01

    As an alternative to water, propylene carbonate (PC) has a good application prospect in the compact pulsed power sources for its breakdown strength higher than that of water, resistivity bigger than 10(9) Ω m, and low freezing temperature (-49 °C). In this paper, the investigation into dielectric breakdown of PC and PC-based nano-fluids (NFs) subjected to high amplitude electric field is presented with microsecond pulses applied to a 1 mm gap full of PC or NFs between spherical electrodes. One kind of NF is composed of PC mixed with 0.5-1.4 vol. % BaTiO3 (BT) nano-particles of mean diameter ≈100 nm and another is mixed with 0.3-0.8 vol. % BT nano-particles of mean diameter ≈30 nm. The experimental results demonstrate the rise of permittivity and improvement of the breakdown strength of NFs compared with PC. Moreover, it is found that there exists an optimum fraction for these NFs corresponding to tremendous surface area in nano-composites with finite mesoscopic thickness. In concrete, the dielectric breakdown voltage of NFs is 33% higher than that of PC as the volume concentration of nano-particles with a 100 nm diameter is 0.9% and the breakdown voltage of NFs is 40% higher as the volume concentration of nano-particles with a 30 nm diameter is 0.6%. These phenomena are considered as the dielectric breakdown voltage of PC-based NFs is increased because the interfaces between nano-fillers and PC matrices provide myriad trap sites for charge carriers, which play a dominant role in the breakdown performance of NFs.

  11. Field emission enhancement of Au-Si nano-particle-decorated silicon nanowires

    PubMed Central

    2011-01-01

    Au-Si nano-particle-decorated silicon nanowire arrays have been fabricated by Au film deposition on silicon nanowire array substrates and then post-thermal annealing under hydrogen atmosphere. Field emission measurements illustrated that the turn-on fields of the non-annealed Au-coated SiNWs were 6.02 to 7.51 V/μm, higher than that of the as-grown silicon nanowires, which is about 5.01 V/μm. Meanwhile, after being annealed above 650°C, Au-Si nano-particles were synthesized on the top surface of the silicon nanowire arrays and the one-dimensional Au-Si nano-particle-decorated SiNWs had a much lower turn-on field, 1.95 V/μm. The results demonstrated that annealed composite silicon nanowire array-based electron field emitters may have great advantages over many other emitters. PMID:21711684

  12. Modeling and simulations of the removal of formaldehyde using silver nano-particles attached to granular activated carbon.

    PubMed

    Shin, SeungKyu; Song, JiHyeon

    2011-10-30

    A combined reaction, consisting of granular activated carbon (GAC) adsorption and catalytic oxidation, has been proposed to improve the removal efficiencies of formaldehyde, one of the major indoor air pollutants. In this study, silver nano-particles attached onto the surface of GAC (Ag-GAC) using the sputtering method were evaluated for the simultaneous catalytic oxidation and adsorption of formaldehyde. The evolution of CO(2) from the silver nano-particles indicated that formaldehyde was catalytically oxidized to its final product, with the oxidation kinetics expressed as pseudo-first order. In addition, a packed column test showed that the mass of formaldehyde removed by the Ag-GAC was 2.4 times higher than that by the virgin GAC at a gas retention time of 0.5s. However, a BET analysis showed that the available surface area and micro-pore volume of the Ag-GAC were substantially decreased due to the deposition of the silver nano-particles. To simulate the performance of the Ag-GAC, the homogeneous surface diffusion model (HSDM), developed for the prediction of the GAC column adsorption, was modified to incorporate the catalytic oxidation taking place on the Ag-GAC surface. The modified HSDM demonstrated that numerical simulations were consistent with the experimental data collected from the Ag-GAC column tests. The model predictions implied that the silver nano-particles deposited on the GAC reduced the adsorptive capacity due to decreasing the available surface for the diffusion of formaldehyde into the GAC, but the overall mass of formaldehyde removed by the Ag-GAC was increased due to catalytic oxidation as a function of the ratio of the surface coverage by the nano-particles.

  13. NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS

    SciTech Connect

    Seetala V. Naidu; Upali Siriwardane; Akundi N. Murty

    2004-02-23

    The preparation of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe nano-particle metal loaded mesoporous 1 mm spherical granular {gamma}-Al{sub 2}O{sub 3} catalysts, by combined sol-gel/oil-drop methods followed by calcination and hydrogenation steps, is accomplished. Parameters for calcination process were optimized using DTA. The properties of metal loaded {gamma}-Al{sub 2}O{sub 3} granules were compared for the preparations starting with two precursors: aluminum tri-sec-butoxide (ALTSB) and aluminum tri-iso-propoxide (ALTIP). Three sol-gel/oil-drop catalyst preparation methods; (1) Metal nitrate solutions co-entrapped-sol-gel (2) nano-particle metal oxide co-entrapped-sol-gel, and (3) Metal impregnation on preformed alumina granules, were used. Structure and composition of metal-loaded-granules were investigated using XRD, SEM, EDX, and surface area measurements (BET method). The nano-particle nature of catalysts was confirmed using SEM and X-ray diffraction. The reduction efficiency of hydrogenation of catalysts was examined by magnetic studies using a vibrating sample magnetometer (VSM). Catalysts could be effectively calcined at 450 C and the surface area values obtained were between 200-350 m{sup 2}/g, indicating the mesoporous nature of catalyst support. Parameters affecting the metal loading process were also studied, and the optimum conditions were identified and reported for reproducible synthesis of the metal loaded {gamma}-alumina granular particles. The catalyst activities of Fe, Co, and Co/Fe on alumina for the conversion of CO/H{sub 2} and CO{sub 2}/H{sub 2} mixtures were investigated using Gas chromatography (GC) with N{sub 2} as a standard carrier gas. Both, slurry-phase-batch and gas-phase-continuous-flow, reactors were used. Magnetization studies on reduced, CO/H{sub 2} post-reaction catalyst in both gas and slurry phase were performed using vibrating sample magnetometer (VSM). Magnetic studies of post-reaction Co and Fe nano-catalysts showed that the

  14. NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS

    SciTech Connect

    Setala V. Naidu

    2003-01-01

    We have produced Co, Cu, and Fe nano-particles by Laser-induced solution deposition (LISD) as evidenced by TEM investigations. Sizes of the nano-particles created are in the order of 5 nm. The LISD system could generate nano-particles in quantities only in the order of a milligram. This may be mainly due to the limited photo induced reactions taking place on the surface of the solutions. We have designed experiments to use drop flow technique with LISD for nano-particle deposition on microreactors. Preliminary work has been done on Co and Fe thin film deposited microreactors. We are also investigating the catalytic properties of nano-particles of FeO and CoO prepared by ball milling and dispersed into sol-gel prepared alumina granules. We have continued our investigation of catalytic reactions of Cu, Co, Fe, Cu/Co, Cu/Fe and Co/Fe on alumina support. The metal oxides were first reduced with hydrogen and used for the conversion of CO/H{sub 2}. The surface area of the catalysts has been determined by nitrogen disorption. They are in the range of 200-300 m{sup 2}/g. Cu, Co, Fe, Co/Fe, Cu/Co and Cu/Fe showed increasing order of catalytic activity for CO/H{sub 2} conversion. We are also studying catalytic conversion rates for CO{sub 2}/H{sub 2} and CO/CO{sub 2}/H{sub 2} mixtures using these catalysts. Our investigations of Co and Fe thin film deposited microreactors showed higher CO/H{sub 2} conversion for Fe compared to Co. We have used vibrating sample magnetometer (VSM) to study the magnetic characteristics of as prepared, reduced, post-reaction catalysts. Comparative study of the ferromagnetic component of these samples gives the reduction efficiency and the changes in metal centers during catalytic reactions. Magnetic studies of post-reaction Co and Fe micro-reactors show that more carbide formation occurs for iron compared to cobalt.

  15. Lead coprecipitation with iron oxyhydroxide nano-particles

    NASA Astrophysics Data System (ADS)

    Lu, Peng; Nuhfer, Noel T.; Kelly, Shelly; Li, Qin; Konishi, Hiromi; Elswick, Erika; Zhu, Chen

    2011-08-01

    Pb 2+ and Fe 3+ coprecipitation was studied with sorption edge measurements, desorption experiments, sorbent aging, High Resolution Transmission and Analytical Electron Microscopy (HR TEM-AEM), and geochemical modeling. Companion adsorption experiments were also conducted for comparison. The macroscopic chemical and near atomic scale HRTEM data supplemented our molecule scale analysis with EXAFS ( Kelly et al., 2008). Coprecipitation of Pb 2+ with ferric oxyhydroxides occurred at ˜pH 4 and is more efficient than adsorption in removing Pb 2+ from aqueous solutions at similar sorbate/sorbent ratios and pH. X-ray Diffraction (XRD) shows peaks of lepidocrocite and two additional broad peaks similar to fine particles of 2-line ferrihydrite (2LFh). HRTEM of the Pb-Fe coprecipitates shows a mixture of 2-6 nm diameter spheres and 8-20 by 200-300 nm needles, both uniformly distributed with Pb 2+. Geochemical modeling shows that surface complexation models fit the experimental data of low Pb:Fe ratios when a high site density is used. Desorption experiments show that more Pb 2+ was released from loaded sorbents collected from adsorption experiments than from Pb to Fe coprecipitates at dilute EDTA concentrations. Desorbed Pb 2+ versus dissolved Fe 3+ data show a linear relationship for coprecipitation (CPT) desorption experiments but a parabolic relationship for adsorption (ADS) experiments. Based on these results, we hypothesize that Pb 2+ was first adsorbed onto the nanometer-sized, metastable, iron oxyhydroxide polymers of 2LFh with domain size of 2-3 nm. As these nano-particles assembled into larger particles, some Pb 2+ was trapped in the iron oxyhydroxide structure and re-arranged to form solid solutions. Therefore, the CPT contact method produced more efficient removal of Pb 2+ than the adsorption contact method, and Pb 2+ bound in CPT solids represent a more stable sequestration of Pb 2+ in the environment than Pb 2+ adsorbed on iron oxyhydroxide surfaces.

  16. Surface modification of magnetite nanoparticle with azobenzene-containing water dispersible polymer

    NASA Astrophysics Data System (ADS)

    Theamdee, Pawinee; Traiphol, Rakchart; Rutnakornpituk, Boonjira; Wichai, Uthai; Rutnakornpituk, Metha

    2011-10-01

    We here report the synthesis of magnetite nanoparticle (MNP) grafted with poly (ethylene glycol) methyl ether methacrylate (PEGMA)-azobenzene acrylate (ABA) statistical copolymer via atom transfer radical polymerization (ATRP) for drug entrapment and photocontrolled release. MNP was synthesized via thermal decomposition of iron (III) acetylacetonate in benzyl alcohol and surface functionalized to obtain ATRP initiating sites. Molar compositions of the copolymer on MNP surface were systematically varied (100:0, 90:10, 70:30, and 50:50 of PEGMA:ABA, respectively) to obtain water dispersible particles with various amounts of azobenzene. The presence of polymeric shell on MNP core was evidenced by transmission electron microscopy (TEM). Drug loading and entrapment efficiencies as well as drug release behavior of the copolymer-MNP complexes were investigated. It was found that when percent of ABA in the copolymers was increased, entrapment and loading efficiencies of prednisolone model drug were enhanced. Releasing rate and percent of the released prednisolone of the complex exposed in UV light were slightly enhanced as compared to the system without UV irradiation. This copolymer-MNP complex with photocontrollable drug release and magnetic field-directed properties is warranted for further studies for potential uses as a novel drug delivery vehicle.

  17. Surface-modified magnetite nanoparticles act as aneugen-like spindle poison.

    PubMed

    Buliaková, Barbora; Mesárošová, Monika; Bábelová, Andrea; Šelc, Michal; Némethová, Veronika; Šebová, Lívia; Rázga, Filip; Ursínyová, Monika; Chalupa, Ivan; Gábelová, Alena

    2017-01-01

    Iron oxide nanoparticles are one of the most promising types of nanoparticles for biomedical applications, primarily in the context of nanomedicine-based diagnostics and therapy; hence, great attention should be paid to their bio-safety. Here, we investigate the ability of surface-modified magnetite nanoparticles (MNPs) to produce chromosome damage in human alveolar A549 cells. Compared to control cells, all the applied MNPs increased the level of micronuclei moderately but did not cause structural chromosomal aberrations in exposed cells. A rise in endoreplication, polyploid and multinuclear cells along with disruption of tubulin filaments, downregulation of Aurora protein kinases and p53 protein activation indicated the capacity of these MNPs to impair the chromosomal passenger complex and/or centrosome maturation. We suppose that surface-modified MNPs may act as aneugen-like spindle poisons via interference with tubulin polymerization. Further studies on experimental animals revealing mechanisms of therapeutic-aimed MNPs are required to confirm their suitability as potential anti-cancer drugs.

  18. Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(caprolactone)/chitosan blends.

    PubMed

    Ghorbani, Fereshte Mohammad; Kaffashi, Babak; Shokrollahi, Parvin; Akhlaghi, Shahin; Hedenqvist, Mikael S

    2016-02-01

    The effect of hydroxyapatite nano-particles (nHA) on morphology, and rheological and thermal properties of PCL/chitosan blends was investigated. The tendency of nHA to reside in the submicron-dispersed chitosan phase is determined using SEM and AFM images. The presence of electrostatic interaction between amide sites of chitosan and ionic groups on the nHA surface was proved by FTIR. It is shown that the chitosan phase is thermodynamically more favorable for the nano-particles to reside than the PCL phase. Lack of implementation of Cox-Merz theory for this system shows that the polymer-nano-particle network is destructed by the flow. Results from dynamic rheological measurements and Zener fractional model show that the presence of nHA increases the shear moduli and relaxation time of the PCL/chitosan blends. DSC measurements showed that nHA nano-particles are responsible for the increase in melting and crystallization characteristics of the PCL/chitosan blends. Based on thermogravimetric analysis, the PCL/chitosan/nHA nano-composites exhibited a greater thermal stability compared to the nHA-free blends.

  19. Geometrical effects on the electron residence time in semiconductor nano-particles

    SciTech Connect

    Koochi, Hakimeh; Ebrahimi, Fatemeh

    2014-09-07

    We have used random walk (RW) numerical simulations to investigate the influence of the geometry on the statistics of the electron residence time τ{sub r} in a trap-limited diffusion process through semiconductor nano-particles. This is an important parameter in coarse-grained modeling of charge carrier transport in nano-structured semiconductor films. The traps have been distributed randomly on the surface (r{sup 2} model) or through the whole particle (r{sup 3} model) with a specified density. The trap energies have been taken from an exponential distribution and the traps release time is assumed to be a stochastic variable. We have carried out (RW) simulations to study the effect of coordination number, the spatial arrangement of the neighbors and the size of nano-particles on the statistics of τ{sub r}. It has been observed that by increasing the coordination number n, the average value of electron residence time, τ{sup ¯}{sub r} rapidly decreases to an asymptotic value. For a fixed coordination number n, the electron's mean residence time does not depend on the neighbors' spatial arrangement. In other words, τ{sup ¯}{sub r} is a porosity-dependence, local parameter which generally varies remarkably from site to site, unless we are dealing with highly ordered structures. We have also examined the effect of nano-particle size d on the statistical behavior of τ{sup ¯}{sub r}. Our simulations indicate that for volume distribution of traps, τ{sup ¯}{sub r} scales as d{sup 2}. For a surface distribution of traps τ{sup ¯}{sub r} increases almost linearly with d. This leads to the prediction of a linear dependence of the diffusion coefficient D on the particle size d in ordered structures or random structures above the critical concentration which is in accordance with experimental observations.

  20. Identification of magnetite in lunar regolith breccia 60016: Evidence for oxidized conditions at the lunar surface

    NASA Astrophysics Data System (ADS)

    Joy, Katherine H.; Visscher, Channon; Zolensky, Michael E.; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Kring, David A.

    2015-07-01

    Lunar regolith breccias are temporal archives of magmatic and impact bombardment processes on the Moon. Apollo 16 sample 60016 is an "ancient" feldspathic regolith breccia that was converted from a soil to a rock at ~3.8 Ga. The breccia contains a small (70 × 50 μm) rock fragment composed dominantly of an Fe-oxide phase with disseminated domains of troilite. Fragments of plagioclase (An95-97), pyroxene (En74-75, Fs21-22,Wo3-4), and olivine (Fo66-67) are distributed in and adjacent to the Fe-oxide. The silicate minerals have lunar compositions that are similar to anorthosites. Mineral chemistry, synchrotron X-ray absorption near edge spectroscopy (XANES) and X-ray diffraction (XRD) studies demonstrate that the oxide phase is magnetite with an estimated Fe3+/ΣFe ratio of ~0.45. The presence of magnetite in 60016 indicates that oxygen fugacity during formation was equilibrated at, or above, the Fe-magnetite or wüstite-magnetite oxygen buffer. This discovery provides direct evidence for oxidized conditions on the Moon. Thermodynamic modeling shows that magnetite could have been formed from oxidization-driven mineral replacement of Fe-metal or desulphurisation from Fe-sulfides (troilite) at low temperatures (<570 °C) in equilibrium with H2O steam/liquid or CO2 gas. Oxidizing conditions may have arisen from vapor transport during degassing of a magmatic source region, or from a hybrid endogenic-exogenic process when gases were released during an impacting asteroid or comet impact.

  1. Fractures as Carriers for Colloid and Nano-Particles

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Cohen, M.; Tang, X.; Zvikelsky, O.; Meron, H.

    2013-12-01

    One of the major questions in studies in which transport of colloids and nano particles (NPs) is being explored is whether or not they will be mobile on large scales and in large conduits such as fractures and cracks. While many studies explore the migration on a small scale and mostly in ideal porous media, less is known about this topic on larger scales and in fractured rocks or cracked soils. Fractures are likely to be favorable carriers for colloids and NPs due to their large aperture, enabling relatively high flow velocity and smaller tortuosity of the flow path. Transport of various colloids including microspheres, clay particles and viruses, as well as colloid-facilitated transport of lead and cesium was explored in a naturally discrete fractured chalk cores. Preliminary work exploring the transport of NZVIs and TiO2 NPs is being carried out through these cores as well. Our results indicate very high recovery of large microspheres (0.2 and 1 micron) and lower recovery of the small spheres (0.02 micron). It was observed that clay particles, with similar surface properties and sizes to that of the microspheres, show significantly lower recoveries (50 vs over 90%), probably due to the high density of clay particles in respect to the microspheres (2.65 vs. 1.05 g/cm3). High recovery of bacteriophages was also observed, but they exhibit some differences in respect to microspheres with similar properties. In all cases, including the 0.02 micron colloids exhibiting lower recovery rates, arrival times were earlier than that of the bromide that was used as a reference. It was found that colloid-facilitated transport played a major role in the migration of lead and cesium through the fracture. In practice, lead was found to be mobile only in a colloidal form. The on-going work on NP transport through fractures is still in a preliminary phase. Nevertheless, TiO2 recovery was found to be very low. In conclusion, it was observed that in many cases fractures are favorable

  2. Adsorption of Heavy Metals in Industrial Wastewater by Magnetic Nano-particles

    NASA Astrophysics Data System (ADS)

    Tu, Y.; You, C.

    2010-12-01

    Industrial wastewater containing heavy metals is of great concern because of their toxic impact to living species and environments. Removal of metal ions from industrial effluent using nano-particles is an area of extensive research. This study collected wastewaters and effluents from 11 industrial companies in tanning, electronic plating, printed circuit board manufacturing, semi-conductor, and metal surface treatment industry and studied in detailed the major and trace element compositions to develop potential fingerprinting technique for pollutant source identification. The results showed that electronic plating and metal surface treatment industry produce high Fe, Mn, Cr, Zn, Ni and Mo wastewater. The tanning industry and the printed circuit board manufacturing industry released wastewater with high Fe and Cr, Cu and Ni, respectively. For semi-conductor industry, significant dissolved In was detected in wastewater. The absorption experiments to remove heavy metals in waters were conducted using Fe3O4 nano-particles. Under optimal conditions, more than 99 % dissolved metals were removed in a few minutes.

  3. Z-scan study of nonlinear absorption of gold nano-particles prepared by ion implantation in various types of silicate glasses

    NASA Astrophysics Data System (ADS)

    Husinsky, W.; Ajami, A.; Nekvindova, P.; Svecova, B.; Pesicka, J.; Janecek, M.

    2012-05-01

    Metal nano-clusters composite glasses synthesized by ion implantation have been shown as promising nonlinear photonic material. In this paper, we report on the nonlinear absorption measurements of gold nano-particles implanted in four structurally different types of silicate glasses. All targets containing gold nano-particles in a layer 500 nm under the surface of the glass have been prepared by ion implantation with subsequent annealing. The targets were characterized by UV-VIS absorption spectroscopy, transmission electron microscopy (TEM) and by the Z-scan technique. The resulting nano-particles differed in size, range of particle size and shape as well as depth distribution characteristic for glasses with different chemical compositions. With the Z-scan technique, it can be shown that the nano-particles produced in silicate glasses exhibit substantial two-photon absorption (TPA). The TPA coefficient differed depending on size, shape, and depth distribution of the metal nano-clusters and the structure and composition of the glass substrates. The highest TPA coefficient (16.25 cm/GW) was found for the glass BK7 in which the largest non-spherical nano-particles have been observed in the thinnest layer.

  4. Aqueous Phase Glycerol Reforming by PtMo Bimetallic Nano-Particle Catalyst: Product Selectivity and Structural Characterization

    SciTech Connect

    Stach E. A.; Dietrich, P.J.; Lobo-Lapidus, R.J.; Wu, T.; Sumer, A.; Akatay, M.C.; Fingland, B.R.; Guo, N.; Dumesic, J.A.; Marshall, C.L.; Jellinek, J.; Delgass, W.N.; Ribeiro, F.H.; Miller, J.T.

    2012-03-01

    A carbon supported PtMo aqueous phase reforming catalyst for producing hydrogen from glycerol was characterized by analysis of the reaction products and pathway, TEM, XPS and XAS spectroscopy. Operando X-ray absorption spectroscopy (XAS) indicates the catalyst consists of bimetallic nano-particles with a Pt rich core and a Mo rich surface. XAS of adsorbed CO indicates that approximately 25% of the surface atoms are Pt. X-ray photoelectron spectroscopy indicates that there is unreduced and partially reduced Mo oxide (MoO{sub 3} and MoO{sub 2}), and Pt-rich PtMo bimetallic nano-particles. The average size measured by transmission electron microscopy of the fresh PtMo nano-particles is about 2 nm, which increases in size to 5 nm after 30 days of glycerol reforming at 31 bar and 503 K. The catalyst structure differs from the most energetically stable structure predicted by density functional theory (DFT) calculations for metallic Pt and Mo atoms. However, DFT indicates that for nano-particles composed of metallic Pt and Mo oxide, the Mo oxide is at the particle surface. Subsequent reduction would lead to the experimentally observed structure. The aqueous phase reforming reaction products and intermediates are consistent with both C-C and C-OH bond cleavage to generate H{sub 2}/CO{sub 2} or the side product CH{sub 4}. While the H{sub 2} selectivity at low conversion is about 75%, cleavage of C-OH bonds leads to liquid products with saturated carbon atoms. At high conversions (to gas), these will produced additional CH{sub 4} reducing the H{sub 2} yield and selectivity.

  5. Silver nano particle formation on Ar plasma - treated cinnamyl alcohol

    SciTech Connect

    Dahle, S.; Marschewski, M.; Wegewitz, L.; Maus-Friedrichs, W.; Vioel, W.

    2012-02-01

    Metastable induced electron spectroscopy, ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy are employed to study the adsorption of silver on cinnamyl alcohol films prepared on Au(111) substrates by thermal evaporation. Additionally, the impact of an Ar atmosphere dielectric barrier discharge plasma applied to the cinnamyl alcohol film preliminary to the Ag adsorption is investigated. In both cases silver nano particles with an average diameter of 9 nm are formed. These particles do not interact chemically with the underlying cinnamyl alcohol film. We do not find any influence of the preliminary Ar plasma-treatment on the adsorption behavior at all.

  6. Rapid laser sintering of metal nano-particles inks

    NASA Astrophysics Data System (ADS)

    Ermak, Oleg; Zenou, Michael; Bernstein Toker, Gil; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-01

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

  7. An Investigation on Effects of TiO2 Nano-Particles Incorporated in Electroless NiP Coatings' Properties

    NASA Astrophysics Data System (ADS)

    Allahkaram, S. R.; Salmi, S.; Tohidlou, E.

    Electroless composite coatings have been vastly used in various industries during last decades due to their good properties, such as corrosion and wear resistance, hardness and uniform thickness. In this paper, co-deposition of TiO2 nano-particles with Nickel-Phosphorus electroless coatings on API-5L-X65 steel substrates was investigated. Surface morphology and composition of coatings were studied via SEM and EDX, respectively. XRD analyses showed that these coatings had amorphous structure with TiO2 crystalline particles. TiO2 nano-particles increased microhardness of coatings. Corrosion resistance of these coatings was tested using linear polarization in 0.5M sulfuric acid electrolyte. Results showed that NiP-TiO2 electroless composite coatings increased corrosion resistance of substrates.

  8. Size dependent fluorescence tuning of naturally occurring betacyanin with silver nano particles

    NASA Astrophysics Data System (ADS)

    Sarkar, Arindam; Thankappan, Aparna; Nampoori, V. P. N.

    2014-10-01

    Light absorption and scattering of metal nano partilces occur in very narrow range of wavelengths. This is also dependent on the geometry and shape of metal nano particles. It is also known that scattering is related to (volume)2 and absorption is related to the volume of the spherical metal nano particles. In our work we show that using this principle metal nano particles enable fluorescence tuning of dyes. In our experiment we show such tuning in naturally occurring betacyanin extracted from red beetroot. We also show that such tuning is dependent on the size variation of the silver nano particles.

  9. Formation and transformation of magnetite (Fe[sub 3]O[sub 4]) on steel surfaces under continuous and cyclic water fog testing

    SciTech Connect

    Nasrazadani, S. ); Raman, A. )

    1993-04-01

    Formation and transformation of magnetite on two selected low-alloy structural steels were studied using cyclic and continuous water fog tests. It is shown that continuous wetting of steel surfaces results in the formation of magnetite as the main constituent of rust formed. However, in wet/dry fog cycles with drying periods of more than 2 min in every 30-min cycle, a defective spinel phase similar to [gamma]-Fe[sub 2]O[sub 3] forms. Continuous wetting and fast rusting appear to be the main criteria for the stability of magnetite. Both the magnetite and the defective spinel phase [gamma]-Fe[sub 2]O[sub 3] transform to [gamma]-FeOOH first and to [alpha]-FeOOH ultimately under repeated drying conditions, mostly controlled by electrochemical oxidation process. Magnetite formed on steel surface in crevices in the open atmosphere is held stable by the lack of electrochemical oxidation conditions or activation energy for spontaneous oxidation in air.

  10. NanoParticle Ontology for Cancer Nanotechnology Research

    PubMed Central

    Thomas, Dennis G.; Pappu, Rohit V.; Baker, Nathan A.

    2010-01-01

    Data generated from cancer nanotechnology research are so diverse and large in volume that it is difficult to share and efficiently use them without informatics tools. In particular, ontologies that provide a unifying knowledge framework for annotating the data are required to facilitate the semantic integration, knowledge-based searching, unambiguous interpretation, mining and inferencing of the data using informatics methods. In this paper, we discuss the design and development of NanoParticle Ontology (NPO), which is developed within the framework of the Basic Formal Ontology (BFO), and implemented in the Ontology Web Language (OWL) using well-defined ontology design principles. The NPO was developed to represent knowledge underlying the preparation, chemical composition, and characterization of nanomaterials involved in cancer research. Public releases of the NPO are available through BioPortal website, maintained by the National Center for Biomedical Ontology. Mechanisms for editorial and governance processes are being developed for the maintenance, review, and growth of the NPO. PMID:20211274

  11. Enhancement of iron content in spinach plants stimulated by magnetic nano particles

    NASA Astrophysics Data System (ADS)

    Yulianto, Agus; Astuti, Budi; Amalia, Saptaria Rosa

    2016-04-01

    In our previous study, the iron content in spinach plants could be detected by magnetic susceptibility values. In the present work, magnetic nano particles were found from the iron sand. The magnetic nano particles are synthesis by using co-precipitation process and sol-gel technique. The stimulation of magnetic nano particles in the plant has been done by the provision of magnetic nano particles in growing media. After certain time, plant samples was characterized using susceptibility-meter MS2B and atomic absorption spectroscopy to measure the magnetic susceptibility and the amount of iron content that absorbed of the plant, respectively. The iron content in the spinach plants was increased when the magnetic nano particles was injected in the growing media.

  12. Simple Model for Gold Nano Particles Concentration Dependence of Resonance Energy Transfer Intensity

    NASA Astrophysics Data System (ADS)

    Hoa, N. M.; Ha, C. V.; Nga, D. T.; Lan, N. T.; Nhung, T. H.; Viet, N. A.

    2016-06-01

    Gold nano particles (GNPs) concentration dependence of the energy transfer occurs between the fluorophores and GNPs is investigated. In the case of theses pairs, GNPs can enhance or quench the fluorescence of fluorophores depending upon the relative magnitudes of two energy transfer mechanisms: i) the plasmonic field enhancement at the fluorophores emission frequencies (plasmon coupled fluorescence enhancement) and ii) the localized plasmon coupled Forster energy transfer from fluorescent particles to gold particles, which quenches the fluorescence. The competition of these mechanisms is depending on the spectral overlap of fluorophores and GNPs, their relative concentration, excitation wavelength. Simple two branches surface plasmon polariton model for GNPs concentration dependence of the energy transfer is proposed. The experimental data and theoretical results confirm our findings.

  13. Rotating Flow of Magnetite-Water Nanofluid over a Stretching Surface Inspired by Non-Linear Thermal Radiation

    PubMed Central

    Mustafa, M.; Mushtaq, A.; Hayat, T.; Alsaedi, A.

    2016-01-01

    Present study explores the MHD three-dimensional rotating flow and heat transfer of ferrofluid induced by a radiative surface. The base fluid is considered as water with magnetite-Fe3O4 nanoparticles. Novel concept of non-linear radiative heat flux is considered which produces a non-linear energy equation in temperature field. Conventional transformations are employed to obtain the self-similar form of the governing differential system. The arising system involves an interesting temperature ratio parameter which is an indicator of small/large temperature differences in the flow. Numerical simulations with high precision are determined by well-known shooting approach. Both uniform stretching and rotation have significant impact on the solutions. The variation in velocity components with the nanoparticle volume fraction is non-monotonic. Local Nusselt number in Fe3O4–water ferrofluid is larger in comparison to the pure fluid even at low particle concentration. PMID:26894690

  14. Rotating Flow of Magnetite-Water Nanofluid over a Stretching Surface Inspired by Non-Linear Thermal Radiation.

    PubMed

    Mustafa, M; Mushtaq, A; Hayat, T; Alsaedi, A

    2016-01-01

    Present study explores the MHD three-dimensional rotating flow and heat transfer of ferrofluid induced by a radiative surface. The base fluid is considered as water with magnetite-Fe3O4 nanoparticles. Novel concept of non-linear radiative heat flux is considered which produces a non-linear energy equation in temperature field. Conventional transformations are employed to obtain the self-similar form of the governing differential system. The arising system involves an interesting temperature ratio parameter which is an indicator of small/large temperature differences in the flow. Numerical simulations with high precision are determined by well-known shooting approach. Both uniform stretching and rotation have significant impact on the solutions. The variation in velocity components with the nanoparticle volume fraction is non-monotonic. Local Nusselt number in Fe3O4-water ferrofluid is larger in comparison to the pure fluid even at low particle concentration.

  15. Fe adsorption on hematite (α-Fe{sub 2}O{sub 3}) (0001) and magnetite (Fe{sub 3}O{sub 4}) (111) surfaces

    SciTech Connect

    Pabisiak, Tomasz; Kiejna, Adam

    2014-10-07

    The structure and electronic properties of different terminations of hematite (0001) and magnetite (111) surfaces upon submonolayer Fe adsorption were studied using the spin-polarized density functional theory (DFT) including the Hubbard correction term U (DFT+U). On both oxides the Fe atoms were adsorbed on the most stable iron and oxygen terminated surfaces. The results show that Fe atoms bind strongly both to hematite and magnetite surfaces, however, the binding is distinctly stronger at the oxygen than at the iron terminated surfaces. For both oxides and surface terminations the binding energy of the Fe decreases with increasing coverage, which indicates substantial repulsive interactions between Fe adatoms. On the hematite surface, the most stable sites for Fe adsorption are bulk continuation sites which result in formation of the Fe-rich terminations. On the magnetite surface, the bulk continuation site is favored only for Fe adsorption on the oxygen terminated surface while on the iron terminated one Fe adsorbs in a position closer to the surface iron layer. Submonolayer coverages of Fe modify substantially the surface electronic structure of the oxides and, depending on the termination, can change its character from half-metallic to insulating one, and vice versa.

  16. The energetics and kinetics of uranyl reduction on pyrite, hematite, and magnetite surfaces: A powder microelectrode study

    NASA Astrophysics Data System (ADS)

    Renock, Devon; Mueller, Megan; Yuan, Ke; Ewing, Rodney C.; Becker, Udo

    2013-10-01

    There are many studies describing the influence of parameters such as pH, pCO2, and complexing ligands on the sorption of the aqueous uranyl species onto mineral surfaces. However, few of these studies describe the reduction reaction mechanisms and the factors that influence the rate of reduction, despite the fact that the oxidation state of uranium is the most important factor controlling the mobility of uranium. In this study, the energetics and kinetics of the U(VI) reduction half-reaction on pyrite, hematite, and magnetite were investigated by electrochemical methods using a powder microelectrode (PME) as the working electrode. Anodic and cathodic peaks corresponding to the 1 e- redox couple, U(VI)/U(V), were identified in cyclic voltammograms of pyrite, hematite, and magnetite at pH 4.5. A second oxidation peak, corresponding to the oxidation of U(IV), was identified and provides evidence for the formation of reduced uranium phase(s) on the mineral surfaces. In addition, uranium-containing precipitates were identified on pyrite surfaces after polarization in a PME. This study identifies the disproportionation of U(V) species on the surface as a possible rate-limiting step in the two-step U(VI) reduction mechanism: (1) charge transfer to form U(V) followed by, (2) a disproportionation reaction that forms U(IV) and U(VI). The Tafel slope (i.e., the derivative of the electrode potential with respect to log [current]) was used to evaluate electrochemical mechanisms. High Tafel slopes (>220 mV/(log unit of current) on all minerals evaluated) suggest that uranyl reduction is mediated by insulating (hydr)oxide layers that are present on the semiconducting mineral surfaces. The onset potential for uranyl reduction was determined for pyrite (>+0.1 V vs. Ag/AgCl), and hematite and magnetite (between-0.02 and-0.1 V vs. Ag/AgCl). The onset potential values establish a baseline kinetic parameter that can be used to evaluate how solution conditions (e.g., dissolved

  17. Near-Field CARS with Micro- and Nano-Particle

    NASA Astrophysics Data System (ADS)

    Ooi, C. H. Raymond

    2010-08-01

    Spatial dependence of coherent anti-Stokes Raman scattering (CARS) intensity and spectra for a spherical particle are studied for different sizes, ranging from micrometers to nanometers. Effects of near field on the spectra are analyzed, showing potential application as nano-sensor in microscopy and imaging. The results can be extended to an array of nanospheres. The CARS process has been developed into a versatile real-time detection technique in spectroscopy and microscopy [1]. In particularly, backscattered ultra-violet CARS implemented on LIDAR system [2] is promising for remote detection of molecular species present in hazardous biological aerosols with microscale dimension. In practice, the aerosols could be in any dimension. Thus, we need to know study a modified the setup of the CARS technique for reliable detection of chemicals in micro- and nano-particles using near-field effects. We have developed a nonlinear semiclassical microscopic theory to describe the CARS spectra for a particle composed of a collection of arbitrarily complex molecules [3] as well as simple few levels quantum systems [2]. The theory provides useful results on the CARS spectra for any observation angle and for any form of laser pulses [3]. Here, we focus on the spectra in the near field. We wish to study how the spectra vary with the near field distance with focused laser pulses. We also analyze to what extend the dimension of the particle and the focusing laser affect the lensing effect which could enhance the backscattered light.

  18. Preparation of tourmaline nano-particles through a hydrothermal process and its infrared emission properties.

    PubMed

    Xue, Gang; Han, Chao; Liang, Jinsheng; Wang, Saifei; Zhao, Chaoyue

    2014-05-01

    Tourmaline nano-particles were successfully prepared via a hydrothermal process using HCl as an additive. The reaction temperature (T) and the concentration of HCI (C(HCl)) had effects on the size and morphology of the tourmaline nano-particles. The optimum reaction condition was that: T = 180 degrees C and C(HCl) = 0.1 mol/l. The obtained nano-particles were spherical with the diameter of 48 nm. The far-infrared emissivity of the product was 0.923. The formation mechnism of the tourmaline nano-particles might come from the corrosion of grain boundary between the tourmaline crystals in acidic hydrothermal conditions and then the asymmetric contraction of the crystals.

  19. Ultrasound-assisted Micro-emulsion Synthesis of a Highly Active Nano-particle Catalyst

    DTIC Science & Technology

    2010-03-01

    Ultrasound-assisted Micro -emulsion Synthesis of a Highly Active Nano -particle Catalyst by Rongzhong Jiang and Charles Rong ARL-TR-5114...ARL-TR-5114 March 2010 Ultrasound-assisted Micro -emulsion Synthesis of a Highly Active Nano -particle Catalyst Rongzhong Jiang and...TYPE DRI 3. DATES COVERED (From - To) 2009 to 2010 4. TITLE AND SUBTITLE Ultrasound-assisted Micro -emulsion Synthesis of a Highly Active Nano

  20. Preparation of silver nano-particles immobilized onto chitin nano-crystals and their application to cellulose paper for imparting antimicrobial activity.

    PubMed

    Li, Zhihan; Zhang, Ming; Cheng, Dong; Yang, Rendang

    2016-10-20

    Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5-12nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus.

  1. Comparative study of three magnetic nano-particles (FeSO4, FeSO4/SiO2, FeSO4/SiO2/TiO2) in plasmid DNA extraction.

    PubMed

    Rahnama, H; Sattarzadeh, A; Kazemi, F; Ahmadi, N; Sanjarian, F; Zand, Z

    2016-11-15

    Recent updates on Magnetic Nano-Particles (MNPs) based separation of nucleic acids have received more attention due to their easy manipulation, simplicity, ease of automation and cost-effectiveness. It has been indicated that DNA molecules absorb on solid surfaces via hydrogen-bonding, and hydrophobic and electrostatic interactions. These properties highly depend on the surface condition of the solid support. Therefore, surface modification of MNPs may enhance their functionality and specification. In the present study, we functionalized Fe3O4 nano-particle surface utilizing SiO2 and TiO2 layer as Fe3O4/SiO2 and Fe3O4/SiO2/TiO2 and then compare their functionality in the adsorption of plasmid DNA molecules with the naked Fe3O4 nano-particles. The result obtained showed that the purity and amount of DNA extracted by Fe3O4 coated by SiO2 or SiO2/TiO2 were higher than the naked Fe3O4 nano-particles. Furthermore, we obtained pH 8 and 1.5 M NaCl as an optimal condition for desorption of DNA from MNPs. The result further showed that, 0.2 mg nano-particle and 10 min at 55 °C are the optimal conditions for DNA desorption from nano-particles. In conclusion, we recommended Fe3O4/SiO2/TiO2 as a new MNP for separation of DNA molecules from biological sources.

  2. Tuning surface coatings of optimized magnetite nanoparticle tracers for in vivo Magnetic Particle Imaging.

    PubMed

    Khandhar, Amit P; Ferguson, R Matthew; Arami, Hamed; Kemp, Scott J; Krishnan, Kannan M

    2015-02-01

    Surface coatings are important components of Magnetic Particle Imaging (MPI) tracers - they preserve their key properties responsible for optimum tracer performance in physiological environments. In vivo, surface coatings form a physical barrier between the hydrophobic SPION cores and the physiological environment, and their design dictates the blood half-life and biodistribution of MPI tracers. Here we show the effect of tuning poly(ethylene glycol) (PEG)-based surface coatings on both in vitro and in vivo (mouse model) MPI performance of SPIONs. Our results showed that varying PEG molecular weight had a profound impact on colloidal stability, characterized using Dynamic Light Scattering (DLS), and the m'(H) response of SPIONs, measured in a 25 kHz/20 mTμ0(-1)max Magnetic Particle Spectrometer (MPS). Increasing PEG molecular weight from 5 kDa to 20 kDa preserved colloidal stability and m'(H) response of ~25 nm SPIONs - the optimum core diameter for MPI - in serum-rich cell culture medium for up to 24 hours. Furthermore, we compared the in vivo circulation time of SPIONs as a function of hydrodynamic diameter and showed that clustered SPIONs can adversely affect blood half-life; critically, SPIONs with clusters had 5 times shorter blood half-life than individually coated SPIONs. We anticipate that the development of MPI SPION tracers with long blood half-lives have potential not only in vascular imaging applications, but also enable opportunities in molecular targeting and imaging - a critical step towards early cancer detection using the new MPI modality.

  3. Effects of anti-CD44 monoclonal antibody IM7 carried with chitosan polylactic acid-coated nano-particles on the treatment of ovarian cancer.

    PubMed

    Yang, Yizhuo; Zhao, Xinghui; Li, Xiuli; Yan, Zhifeng; Liu, Zhongyu; Li, Yali

    2017-01-01

    Failure in early diagnosis and ineffective treatment are the major causes of ovarian cancer mortality. Hyaluronan and its receptor, cluster of differentiation (CD)44, have been considered to be valid targets for treating cancer. The anti-CD44 monoclonal antibody IM7 is effective in treating ovarian cancer; however, its toxicity should not be ignored. The present study has developed a new drug carrier system composed of chitosan nano-particles coated with polylactic acid (PLA) to improve the treatment efficacy and reduce toxicity. An ionic crosslinking method and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide were used to prepare the IM7 antibody, which was loaded with chitosan nano-particles. The surfaces of the nano-particles were coated with PLA to generate PLA-chitosan-IM7. Subsequently, transmission electron microscopy (TEM) was used to observe the size and zeta potential of the nano-particles. In addition, a spectrophotometer was used to calculate the loading rate and release rate of the nano-particles in acidic and neutral environments. MTT assay was used to evaluate the anti-proliferative effect of PLA-chitosan-IM7 on the human ovarian cancer cell line HO-8910PM. In addition, an in vivo imaging system was used to further investigate the effect of PLA-chitosan-IM7 on the treatment of mice with ovarian cancer. A total of 35 days subsequent to PLA-chitosan-IM7 treatment, all animals were sacrificed by CO2, and the tumors were removed and weighted. The PLA-chitosan-IM7 nano-particles were successfully prepared, since TEM revealed that their size was 300-400 nm and their zeta potential was +25 mV. According to the spectrophotometry results, the loading rate was 52%, and PLA-chitosan-IM7 exhibited good resistance to acids. MTT assay demonstrated that PLA-chitosan-IM7 could suppress the proliferation of HO-8910PM cells in vitro. The in vivo imaging system revealed that PLA-chitosan-IM7 was effective in controlling the development

  4. Effects of anti-CD44 monoclonal antibody IM7 carried with chitosan polylactic acid-coated nano-particles on the treatment of ovarian cancer

    PubMed Central

    Yang, Yizhuo; Zhao, Xinghui; Li, Xiuli; Yan, Zhifeng; Liu, Zhongyu; Li, Yali

    2017-01-01

    Failure in early diagnosis and ineffective treatment are the major causes of ovarian cancer mortality. Hyaluronan and its receptor, cluster of differentiation (CD)44, have been considered to be valid targets for treating cancer. The anti-CD44 monoclonal antibody IM7 is effective in treating ovarian cancer; however, its toxicity should not be ignored. The present study has developed a new drug carrier system composed of chitosan nano-particles coated with polylactic acid (PLA) to improve the treatment efficacy and reduce toxicity. An ionic crosslinking method and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide were used to prepare the IM7 antibody, which was loaded with chitosan nano-particles. The surfaces of the nano-particles were coated with PLA to generate PLA-chitosan-IM7. Subsequently, transmission electron microscopy (TEM) was used to observe the size and zeta potential of the nano-particles. In addition, a spectrophotometer was used to calculate the loading rate and release rate of the nano-particles in acidic and neutral environments. MTT assay was used to evaluate the anti-proliferative effect of PLA-chitosan-IM7 on the human ovarian cancer cell line HO-8910PM. In addition, an in vivo imaging system was used to further investigate the effect of PLA-chitosan-IM7 on the treatment of mice with ovarian cancer. A total of 35 days subsequent to PLA-chitosan-IM7 treatment, all animals were sacrificed by CO2, and the tumors were removed and weighted. The PLA-chitosan-IM7 nano-particles were successfully prepared, since TEM revealed that their size was 300–400 nm and their zeta potential was +25 mV. According to the spectrophotometry results, the loading rate was 52%, and PLA-chitosan-IM7 exhibited good resistance to acids. MTT assay demonstrated that PLA-chitosan-IM7 could suppress the proliferation of HO-8910PM cells in vitro. The in vivo imaging system revealed that PLA-chitosan-IM7 was effective in controlling the

  5. Electron Temperature and Density Variation Due To Temporal Evolution of Nano Particle Growth in RF Silane Plasma

    SciTech Connect

    Chai, K. B.; Seon, C. R.; Choe, W.; Park, S.; Chung, C. W.

    2008-09-07

    Nano particles, generated in various processing plasmas, have been extensively studied for applications in the fabrication of microelectronics devices. However, studies to find the relation between the particle parameters (particle size and density) and the plasma parameters (electron temperature and density) have been limited because of the availability of the appropriate diagnostic method. The utilization of Langmuir probes are limited in many cases due to the probe tip contamination and the presence of abundant negative ions and particles. In this work, measurements of electron temperature and ion density were performed in rf silane plasmas using a floating probe, which allows an accurate measurement even under harsh plasma environments. The size and density of nano particles were measured by the laser light scattering and the laser extinction method at various gas pressures. It was found that the temporal evolution of the particle growth played a significant role in changing the plasma parameters due to the electron and ion fluxes to the particles. The relation between the plasma parameters and the particle parameters was described by a power balance equation including the power loss to the particle surface.

  6. Coupling Fe0 nano particles with living and dead Azolla filicoloides to improve removal of methylene blue from aqueous solution

    NASA Astrophysics Data System (ADS)

    Rakhshaee, Roohan

    2015-11-01

    Fe0 nano particles (FNPs) were connected to the cell wall of the dead and living Azolla filicoloides as an aquatic fern, individually. FNPs mean size was decreased due to the stabilization, especially using the living one. It was compared the results of X-ray photoelectron spectroscopy (XPS), saturation magnetization (Ms), zeta potential (ZP) and thermal analysis (DSC and TGA) of the dead and living Azolla connected to FNPs, and also the findings of potentiometric titration (PT) of the cell wall's pectin of the dead and living Azolla. It was confirmed (by XRD and XPS) that Fe0 nano particles when were connected to the living Azolla did not produce Fe3O4 due to oxidation unlike the bare FNPs and the connected form to the dead Azolla, by reason of the more stabilization (more surface protection) of nano iron particles after connecting to the living Azolla. To adsorb methylene blue by these agents at the optimum pre-treatment pH 10 and adsorption pH 8, the parameters of equilibrium sorption, rate constant of second-order sorption and activation energy were obtained as: living Azolla-FNPs > dead Azolla-FNPs > FNPs > dead Azolla, while, their thermodynamic parameters (ΔG°, ΔH° and ΔS°) had the reverse arrangement. It was also studied the various factors rule such as photoperiod and the presence of heavy metals on the living Azolla growth coupled with FNPs and its MB removal ability.

  7. Direct Write Processing of Multi-micron Thickness Copper Nano-particle Paste on Flexible Substrates with 532 nm Laser Wavelength

    NASA Astrophysics Data System (ADS)

    Lopez-Espiricueta, Dunia; Fearon, Eamonn; Edwardson, Stuart; Dearden, Geoffrey

    The Laser Assisted Direct Write (LA-DW) method has been implemented in the development of different markets and material processing, recently also used for creating Printed Circuit Boards (PCB) or electrical circuitry. The process consists in the deposition of metallic nano-particle (NP) inks, which are afterwards cured or sintered by laser irradiation, thus creating conductive pathways; advantages are speed, accuracy and the protection of the heat affected zone (HAZ). This research will study the behaviour of the heat dissipation relatively within the Nano-particle Copper paste after being irradiated with 1064 nm and 532 nm wavelengths, research will be developed on different widths and depths deposited onto flat surfaces such as flexible PET. Comparisons to be made between resistivity results obtained from different wavelengths.

  8. Magnetite nano-islands on silicon-carbide with graphene

    DOE PAGES

    Anderson, Nathaniel A.; Zhang, Qiang; Hupalo, Myron; ...

    2017-01-05

    X-ray magnetic circular dichroism (XMCD) measurements of iron nano-islands grown on graphene and covered with a Au film for passivation reveal that the oxidation through defects in the Au film spontaneously leads to the formation of magnetite nano-particles (i.e, Fe3O4). The Fe nano-islands (20 and 75 monolayers; MLs) are grown on epitaxial graphene formed by thermally annealing 6HSiC( 0001) and subsequently covered, in the growth chamber, with nominal 20 layers of Au. Our X-ray absorption spectroscopy and XMCD measurements at applied magnetic fields show that the thin film (20 ML) is totally converted to magnetite whereas the thicker lm (75more » ML) exhibits properties of magnetite but also those of pure metallic iron. Temperature dependence of the XMCD signal (of both samples) shows a clear transition at TV ≈ 120 K consistent with the Verwey transition of bulk magnetite. These results have implications on the synthesis of magnetite nano-crystals and also on their regular arrangements on functional substrates such as graphene.« less

  9. Cylindrical dielectric barrier discharge plasma catalytic effect on chemical methods of silver nano-particle production

    NASA Astrophysics Data System (ADS)

    Bahrami, Zahra; Khani, Mohammad Reza; Shokri, Babak

    2016-11-01

    In this study, cylindrical dielectric barrier discharge plasma was used to study the catalytic effect on chemical methods of silver nano-particles for the first time. In this method, the processing time is short and the temperature of reaction is low. Also, the reactor is very simple, inexpensive, and accessible. In this work, pure AgNO3 as the precursor agent and poly vinyl pyrrolidone as the macromolecular surfactant were dissolved in ethanol as the solvent. UV-Vis and XRD were used to identify the colloidal and powder nano-particles, respectively. Optical emission spectroscopy was also used to identify the active species in plasma. Effects of gas flow rate, voltage, volume of solution, and processing time were also studied. Moreover, TEM and SEM images presented the mean diameter of nano-particle size around 10 to 20 nm. The results have been very promising.

  10. Indentation analysis of nano-particle using nano-contact mechanics models during nano-manipulation based on atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Daeinabi, Khadijeh; Korayem, Moharam Habibnejad

    2011-03-01

    Atomic force microscopy is applied to measure intermolecular forces and mechanical properties of materials, nano-particle manipulation, surface scanning and imaging with atomic accuracy in the nano-world. During nano-manipulation process, contact forces cause indentation in contact area between nano-particle and tip/substrate which is considerable at nano-scale and affects the nano-manipulation process. Several nano-contact mechanics models such as Hertz, Derjaguin-Muller-Toporov (DMT), Johnson-Kendall-Roberts-Sperling (JKRS), Burnham-Colton-Pollock (BCP), Maugis-Dugdale (MD), Carpick-Ogletree-Salmeron (COS), Pietrement-Troyon (PT), and Sun et al. have been applied as the continuum mechanics approaches at nano-scale. In this article, indentation depth and contact radius between tip and substrate with nano-particle for both spherical and conical tip shape during nano-manipulation process are analyzed and compared by applying theoretical, semiempirical, and empirical nano-contact mechanics models. The effects of adhesion force, as the main contrast point in different nano-contact mechanics models, on nano-manipulation analysis is investigated for different contact radius, and the critical point is discussed for mentioned models.

  11. Photocatalytic removal of doxycycline from aqueous solution using ZnO nano-particles: a comparison between UV-C and visible light.

    PubMed

    Pourmoslemi, Shabnam; Mohammadi, Ali; Kobarfard, Farzad; Amini, Mohsen

    2016-10-01

    Zinc oxide nano-particles were synthesized, characterized and used for photocatalytic degradation of doxycycline using UV-C and visible light. Effects of several operational factors including initial pH of antibiotic solution, initial antibiotic concentration and ZnO nano-particles loading amount were investigated. Comparing photocatalytic degradation and mineralization of doxycycline under UV-C and visible light showed successful application of the method under both light sources. However, reaction rate was higher under UV-C irradiation, which degraded doxycycline almost completely in 5 hours, and 68% mineralization was achieved. Synthesized ZnO nano-particles were successfully applied for photocatalytic degradation of doxycycline in a pharmaceutical wastewater sample. The process was fitted to the pseudo first order kinetic model with rate constants in the range of 6-22(×10(-3)) mg L(-1) min(-1) with respect to initial concentration of doxycycline under UV-C irradiation. The Langmuir-Hinshelwood model was also employed for describing the photocatalytic reaction with surface reaction kinetic constant kc and equilibrium adsorption constant KLH values calculated as 0.12 mg L(-1) min(-1) and 2.2 L mg(-1), respectively. Degradation of doxycycline was followed by UV-visible spectroscopy and a validated stability indicating high-performance liquid chromatography method that was developed using stressed samples of doxycycline and could selectively determine doxycycline in the presence of its degradation products. Mass spectrometry was used for determining final degradation products.

  12. Chemi-resistive response of rutile titania nano-particles towards isopropanol and formaldehyde: a correlation with the volatility and chemical reactivity of vapors

    NASA Astrophysics Data System (ADS)

    Das, P.; Mondal, B.; Mukherjee, K.

    2017-01-01

    The performance of phase pure rutile titania nano-particles for gas/vapor sensing is not well explored in open literature, mostly because of their moderate chemical activity. However, the high thermal stability of rutile titania could be beneficial towards making a stable chemi-resistive sensor, operable generally at higher temperature. Herein, we have investigated the chemi-resistive response characteristics of rutile phase titania nano-particles for the detection of isopropanol and formaldehyde vapors. Titania nano-particles are synthesized through a hydrothermal route and characterized in terms of their phase formation behavior and micro-structural features. The sensing characteristics of the particles are measured by varying the operating temperature (275 °C–350 °C) of the sensor and concentrations (20–200 ppm) of the vapors, using a static flow gas sensing measurement set-up. The rutile titania particles are found more responsive towards isopropanol than formaldehyde. An attempt is made here to correlate the sensing performance of titania sensors with the volatility and chemical reactivity of studied vapors. The higher response of the sensor towards isopropanol is predicted, due to its comparatively lower volatility and more suitable chemical structure for oxidation on the sensor surface.

  13. Magnetic behaviour of nano-particles of Fe2.9Zn0.1O4

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Kumar, Sudhish; Krishnamurthy, Anjali; Srivastava, Bipin K.; Aswal, V. K.

    2003-09-01

    DC magnetization measurements are reported in the temperature range 20-300 K on a poly-disperse nano-particle sample of the spinel ferrite Fe_{2.9}Zn_{0.1}O_4 with a log-normal size distribution of median diameter 43.6 Å and standard deviation 0.58. Outside a core of ordered spins, moments in surface layer are disordered. Results also show some similarities with conventional spin glasses. Blocking temperature exhibits a near linear variation with two-third power of the applied magnetic field and magnetization M evolves nearly linearly with logarithm of time t. Magnetic anisotropy has been estimated by analysing the M-log t curve. Anisotropy values show a large increase over that of bulk particle samples. Major contribution to this enhancement comes from the disordered surface spins.

  14. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Horchani, R.

    2016-02-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

  15. Asymmetric transport of light in linearly arrayed metallic nano-particles

    NASA Astrophysics Data System (ADS)

    Aroua, W.; Horchani, R.; AbdelMalek, F.; Haxha, S.; Kamli, Ali A.

    2016-09-01

    A strong asymmetric light transport in a linear chain of spherical and equidistantly spaced silver metal nano-particles (MNPs) located near a substrate is reported. The contrast ratio of the proposed structure is above 0.95. We have studied the propagation of light in the array with respect to the metal and the size of the last nano-particle of the chain and the nature of the substrate. It is shown also that the presence of a copper or gold substrate enhance the guiding properties of the array. This structure opens the possibility to design various optical devices such as broadband antennae and optical diodes.

  16. Synthesis and characterization of pure Cu and CuO nano particles by solution combustion synthesis

    NASA Astrophysics Data System (ADS)

    Patil, Sarika P.; Patil, Shital P.; Puri, V. R.; Jadhav, L. D.

    2013-06-01

    The Cu and CuO nano particles were prepared by using solution combustion technique with copper nitrate as an oxidizer and citric acid as the fuel. The solution combustion synthesis (SCS) method provides the advanced ceramics, nano-composites and catalyst materials and also produces homogeneous, crystalline and un-agglomerated multi-component oxides. The pure CuO nano particles were prepared for rich oxidant to fuel ratio. As prepared powder were further calcined at 600 °C for 2 hrs. The powder was characterized by different techniques such as XRD, TG-DTA, and SEM etc.

  17. Improved light extraction with nano-particles offering directional radiation diagrams

    SciTech Connect

    Jouanin, A.; Hugonin, J. P.; Besbes, M.; Lalanne, P.

    2014-01-13

    We propose a unique approach for light extraction, using engineered nano-particles to efficiently decouple the light guided in transverse-magnetic guided modes into free-space radiation modes that leak out normally to the thin-film stacks. The underlying mechanism takes advantage of a small electric field variation at the nano-particle scale and induces a “polarization conversion,” which renders the induced dipole moment perpendicular to the polarization of the incident light. Our analysis is supported by 2D fully vectorial computational results. Potential applications for light emitting or photovoltaic devices are outlined.

  18. Yb-doped yttria-alumino-silicate nano-particles based optical fibers: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Paul, M. C.; Pal, M.; Kir'yanov, A. V.; Das, S.; Bhadra, S. K.; Barmenkov, Yu. O.; Martinez-Gamez, A. A.; Lucio-Martínez, J. L.

    2012-04-01

    An efficient method to fabricate transparent glass ceramic fibers containing in-situ grown Yb 3+ doped oxide nano-particles based on yttria-alumino-silicate glass is presented. These large-mode area Yb 3+ doped fibers having a core diameter around 25.0 μm were drawn by a proper control over the involved process parameters; by this, the size of nano-particles was maintained within 5-10 nm. The main spectroscopic and laser properties of the fabricated fibers along with the nano-structuration results are reported. These results reveal that the developed method offers new scopes for the contemporary Yb 3+ fiber based devices.

  19. Magnetite and its production

    SciTech Connect

    Koebbe, E.R.

    1993-12-31

    The supply of high quality magnetite for the cleaning of coal using dense medium cyclones and vessels is of concern to all coal preparation operations. This paper describes the production of high purity magnetite (Fe{sub 3}O{sub 4}) from a domestic underground mining operation in Missouri, Pea Ridge Iron Ore Company. Emphasis will be placed on the mining and processing of the magnetite ore into the various magnetite products required by coal preparation plants.

  20. Magnetite seeded precipitation of phosphate.

    PubMed

    Karapinar, Nuray; Hoffmann, Erhard; Hahn, Hermann H

    2004-07-01

    Seeded precipitation of Ca phosphate on magnetite mineral (Fe3O4) surfaces was investigated using a Jar Test system in supersaturated solutions at 20 degrees C and ionic strength 0.01 mol l(-1) with relative super saturation, 12.0-20.0 for HAP. pH of the solution, initial phosphorus concentration and molar Ca/P ratio were investigated as the main parameters, which effect the seeded precipitation of Ca phosphate. Results showed that there is no pronounced effect of magnetite seed, neither positive nor negative on the amount of calcium phosphate precipitation. pH was found to be the main parameter that determines the phosphate precipitated onto the seed surface. Increasing of the pH of precipitation reaction was resulted in the decrease in percentage amount of phosphate precipitated onto seed surfaces to total precipitation (magnetite seeded precipitation efficiency). It was concluded that the pH dependence of magnetite-seeded precipitation should be considered in the light of its effect on the supersaturated conditions of solution. Saturation index (SI) of solution with respect to the precipitate phase was considered the driving force for the precipitation. A simulation programme PHREEQC (Version 2) was employed to calculate the Saturation-index with respect to hydroxyapatite (HAP) of the chemically defined precipitation system. It was found a good relationship between SI of solution with respect to HAP and the magnetite seeded precipitation efficiency, a second order polynomial function. Results showed that more favorable solution conditions for precipitation (higher SI values of solution) causes homogenous nucleation whereas heterogeneous nucleation led to a higher magnetite seeded precipitation efficiency.

  1. Development of Molecularly Imprinted Olanzapine Nano-particles: In Vitro Characterization and In Vivo Evaluation.

    PubMed

    Jafary Omid, Nersi; Morovati, Hoda; Amini, Mohsen; Dehpour, Ahmad-Reza; Partoazar, Alireza; Rafiee-Tehrani, Morteza; Dorkoosh, Farid

    2016-12-01

    Molecularly imprinted nano-particles (MINPs) selective for olanzapine were prepared using methacrylic acid (MA) as monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, and 2,2-azobis (2-isobutyronitrile) (AIBN) as the initiator in 36 different ratios. The reaction runs with considerable fine powder formation were selected for further binding and selectivity studies. The MINP with the best selectivity (MINP-32) was chosen for further structural characterization by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), adsorption-desorption isotherm for specific surface area, volume and average pore diameter determination. All characterization methods confirmed the successful formation of MINP. The optimum conditions for maximum template loading on the MINP-32 were found by experimental design using response surface methodology (RSM) and choosing absorbent amount, pH, and time as the main factors. MINPs with maximum template loading also indicated significant selectivity between template and its analog (clozapine). The release profile demonstrated a maximum release of about 95% after 288 h for MINP-32 in comparison with about 94% after 120 h for non-MINP-32. The same slow release of drug from MINP-32 was also observed during animal study of the plasma level of template, 20-28 μg/ml versus 5-10 μg/ml. The MINP-32 of this study represents a desirable ability to keep the memory of the template with significant selectivity and good capability to control the release of template in vitro and in vivo and hence could be a promising drug delivery system.

  2. Core-shell magnetite-silica dithiocarbamate-derivatised particles achieve the Water Framework Directive quality criteria for mercury in surface waters.

    PubMed

    Lopes, C B; Figueira, P; Tavares, D S; Lin, Z; Daniel-da-Silva, A L; Duarte, A C; Rocha, J; Trindade, T; Pereira, E

    2013-09-01

    The sorption capacity of nanoporous titanosilicate Engelhard titanosilicate number 4 (ETS-4) and silica-coated magnetite particles derivatised with dithiocarbamate groups towards Hg(II) was evaluated and compared in spiked ultra-pure and spiked surface-river water, for different batch factors. In the former, and using a batch factor of 100 m(3)/kg and an initial Hg(II) concentrations matching the maximum allowed concentration in an effluent discharge, both materials achieve Hg(II) uptake efficiencies in excess of 99 % and a residual metal concentration lower than the guideline value for drinking water quality. For the surface-river water and the same initial concentration, the Hg(II) uptake efficiency of magnetite particles is outstanding, achieving the quality criteria established by the Water Framework Directive (concerning Hg concentration in surface waters) using a batch factor of 50 m(3)/kg, while the efficiency of ETS-4 is significantly inferior. The dissimilar sorbents' Hg(II) removal efficiency is attributed to different uptake mechanisms. This study also highlights the importance of assessing the effective capacity of the sorbents under realistic conditions in order to achieve trustable results.

  3. Interfacial Properties and Iron Binding to Bacterial Proteins That Promote the Growth of Magnetite Nanocrystals: X-ray Reflectivity and Surface Spectroscopy Studies

    SciTech Connect

    Wang, Wenjie; Bu, Wei; Wang, Lijun; Palo, Pierre E.; Mallapragada, Surya; Nilsen-Hamilton, Marit; Vaknin, David

    2012-04-30

    Surface sensitive X-ray scattering and spectroscopic studies have been conducted to determine structural properties of Mms6, the protein in Magnetospirillum magneticum AMB-1 that is implicated as promoter of magnetite nanocrystals growth. Surface pressure versus molecular area isotherms indicate Mms6 forms stable monolayers at the aqueous/vapor interface that are strongly affected by ionic conditions of the subphase. Analysis of X-ray reflectivity from the monolayers shows that the protein conformation at the interface depends on surface pressure and on the presence of ions in the solutions, in particular of iron ions and its complexes. X-ray fluorescence at grazing angles of incidence from the same monolayers allows quantitative determination of surface bound ions to the protein showing that ferric iron binds to Mms6 at higher densities compared to other ions such as Fe{sup 2+} or La{sup 3+} under similar buffer conditions.

  4. Near-field optical mapping of single gold nano particles using photo-induced polymer movement of azo-polymers

    NASA Astrophysics Data System (ADS)

    Ishitobi, Hidekazu; Kobayashi, Taka-aki; Ono, Atsushi; Inouye, Yasushi

    2017-03-01

    In this study, polymer movement was induced in azo-polymer films by optical near-fields generated in the vicinity of single gold nano particles (GNPs) to visualize near-field distribution with a spatial resolution beyond the diffraction limit of light. A linearly polarized (Ex) laser beam was irradiated into GNPs to excite local surface plasmon resonance that enhanced the near-field around the GNPs. The findings indicated that different GNP diameters (that is, 50 nm and 80 nm) resulted in different deformation patterns on the films. The results were compared with theoretical calculations of near-field distributions, and the observations revealed that the deformation patterns were dependent on the ratio between Ex and Ey wherein each possessed a different field distribution.

  5. The resistance to chloride penetration of concrete containing nano-particles for pavement

    NASA Astrophysics Data System (ADS)

    Zhang, Mao-hua; Li, Hui

    2006-03-01

    The resistance to chloride penetration of concrete containing nano-particles (TiO II and SiO II) for pavement is experimentally investigated and compared with that of plain concrete, the concrete containing polypropylene (PP) fibers and the concrete containing both nano-particles and PP fibers. The test results indicate that the addition of nano-particles (TiO II and SiO II) improves the resistance to chloride penetration of concrete. The effectiveness of nano-TiO II in improving the resistance to chloride penetration reduces with increasing content of nano-TiO II, and the similar results can be found for the concrete containing nano-SiO II. The resistance to chloride penetration of concrete containing nano-TiO II is better than that containing the same amount of nano-SiO II. However, the resistance to chloride penetration of concrete containing PP fibers is decreased. The larger the content of PP fibers is, the lower the resistance to chloride penetration of concrete is. For the concrete containing both nano-particles and PP fibers, the resistance to chloride penetration is also reduced and even lower than the concrete only containing the same amount of PP fibers. The relationship between the chloride diffusion coefficient and compressive strength of concrete approaches hyperbola basically, which shows that the resistance to chloride penetration of concrete enhances with increasing compressive strength and proves that compressive strength is an important factor influencing the resistance to chloride penetration of concrete.

  6. In Vitro Cytotoxicity Assessment of an Orthodontic Composite Containing Titanium-dioxide Nano-particles.

    PubMed

    Heravi, Farzin; Ramezani, Mohammad; Poosti, Maryam; Hosseini, Mohsen; Shajiei, Arezoo; Ahrari, Farzaneh

    2013-01-01

    Background and aims. Incorporation of nano-particles to orthodontic bonding systems has been considered to prevent enamel demineralization around appliances. This study investigated cytotoxicity of Transbond XT adhesive containing 1 wt% titanium dioxide (TiO2) nano-particles. Materials and methods. Ten composite disks were prepared from each of the conventional and TiO2-containg composites and aged for 1, 3, 5, 7 and 14 days in Dulbecco's Modified Eagle's Medium (DMEM). The extracts were obtained and exposed to culture media of human gingival fibroblasts (HGF) and mouse L929 fibroblasts. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results. Both adhesives were moderately toxic for HGF cells on the first day of the experiment, but the TiO2-containing adhesive produced significantly lower toxicity than the pure adhesive (P<0.05). No significant differences were found in cell viability percentages between the two groups on the other days (P>0.05). There was a significant reduction in cell toxicity with increasing pre-incubation time (P<0.001). L929 cells showed similar toxicity trends, but lower sensitivity to detect cytotoxicity of dental composites. Conclusion. The orthodontic adhesive containing TiO2 nano-particles indicated comparable or even lower toxicity than its nano-particle-free counterpart, indicating that incorporation of 1 wt% TiO2 nano-particles to the composite structure does not result in additional health hazards compared to that occurring with the pure adhesive.

  7. Biological Experiments in Microgravity Conditions Using Magnetic Micro- and Nano-Particles

    NASA Astrophysics Data System (ADS)

    Nechitailo, Galina S.; Kuznetsov, Anatoli; Kuznetsov, Oleg

    2016-07-01

    even for weak magnetic objects, and can have significant effects on multiple processes in living cells/organisms. It was reported, that such high gradient magnetic fields can affect cell differentiation and cell proliferation processes in ground-based experiments. To prevent oxidation of ultradisperse ferromagnetic particles in aqueous media, it is beneficial to coat their surface with carbon. Suitable protected metallic micro- and nano-particles can be produced by a variety of techniques (CVD, plasmachemistry, joint grinding, etc.). Ferro-carbon particles produced by plasmachemical technique have high sorption capacities for various organic and inorganic compounds (as well as for various cell metabolites), can be formed in rather stable aqueous suspensions, and be controlled (e.g., sedimented) by a magnetic field. This makes these particles a very interesting research tool. In our opinion, biological experiments with ferro-carbon nano-structured particles in microgravity will generate important scientific data and will allow creating new methods of negating the adverse effects of microgravity on living systems.

  8. Secondary nuclear targeting of mesoporous silica nano-particles for cancer-specific drug delivery based on charge inversion

    PubMed Central

    Wang, Xiyong; Fan, Xiaobo; Wu, Guoqiu

    2016-01-01

    A novel multifunctional nano-drug delivery system based on reversal of peptide charge was successfully developed for anticancer drug delivery and imaging. Mesoporous silica nano-particles (MSN) ~50 nm in diameter were chosen as the drug reservoirs, and their surfaces were modified with HIV-1 transactivator peptide-fluorescein isothiocyanate (TAT-FITC) and YSA-BHQ1. The short TAT peptide labeled with FITC was used to facilitate intranuclear delivery, while the YSA peptide tagged with the BHQ1 quencher group was used to specifically bind to the tumor EphA2 membrane receptor. Citraconic anhydride (Cit) was used to invert the charge of the TAT peptide in neutral or weak alkaline conditions so that the positively charged YSA peptide could combine with the TAT peptide through electrostatic attraction. The FITC fluorescence was quenched by the spatial approach of BHQ1 after the two peptides bound to each other. However, the Cit-amino bond was unstable in the acidic atmosphere, so the positive charge of the TAT peptide was restored and the positively charged YSA moiety was repelled. The FITC fluorescence was recovered after the YSA-BHQ1 moiety was removed, and the TAT peptide led the nano-particles into the nucleolus. This nano-drug delivery system was stable at physiological pH, rapidly released the drug in acidic buffer, and was easily taken up by MCF-7 cells. Compared with free doxorubicin hydrochloride at an equal concentration, this modified MSN loaded with doxorubicin molecules had an equivalent inhibitory effect on MCF-7 cells. This nano-drug delivery system is thus a promising method for simultaneous cancer diagnosis and therapy. PMID:27661121

  9. Synthesis and Oxidation of Silver Nano-particles

    DTIC Science & Technology

    2011-01-01

    plating process [16]. Firstly, the substrate with the NWs was immersed into the diluted stannous chloride solution, and then extra Sn2 + ions were removed...by de-ionized water rinsing and keeping the surface wet. Hence Sn2 + ions were absorbed on the surface of the ZnO NWs via electrostatic interaction...process, the surface Sn2 + ions were oxidized to Sn4+, while the Ag+ ions were reduced to neutral Ag and deposited on the ZnO nanowire surface

  10. From Neutral Clusters to Nano-particles: Recent Progress in Laboratory and Field Measurements

    NASA Astrophysics Data System (ADS)

    Zhao, J.; Kuang, C.; Titcombe, M.; Rathbone, J.; Eisele, F.; McMurry, P.

    2008-12-01

    Nano-particles produced by nucleation are believed to contribute significantly to the formation of aerosol particles and cloud condensation nuclei (CCN) and hence affect the cloud formation and the atmospheric radiation budget. Nano-particles have also been found to have more adverse human health effect than larger particles. Molecular clusters bridge the gap between molecules and macroscopic nano-particles in the atmosphere. Information on the composition and concentrations of molecular clusters will help to elucidate the nucleation process and reduce the uncertainty of the nucleation rates used in global climate models. We have recently developed a novel chemical ionization mass spectrometer, the cluster chemical ionization mass spectrometer (the Cluster-CIMS), which is capable of measuring the pre-nucleation clusters in the laboratory and in the atmosphere. Together with the recently-implemented particle instruments, we measured the size distribution of the nano particles (~ 1-3 nm) simultaneously with the cluster-CIMS. Here we present the results from recent laboratory studies and field measurements at two distinct sites (Boulder and Manitou Forest). We show an experimental approach to distinguish neutral clusters from the secondary ion clusters under the current configuration of the cluster-CIMS. For the laboratory measurements, we added additional in-situ generated sulfuric acid (~108-109 molecule cm-3) and ammonia (0.1-10ppb) to the ambient air to simulate the cluster formation during the winter time when the ambient sulfuric acid concentration is low and obtained the sulfuric acid/ammonia cluster (up to 7-mers) distribution. For ambient measurements in Boulder, where we occasionally sampled in plumes from power plants, we observed high correlations of sulfur dioxide, sulfuric acid and its dimer with 1.2-1.8 nm nano-particles. We also observed that nano-particle concentrations were well correlated with certain meteorological parameters (e.g. UV radiation, RH

  11. Transmission Electron Microscopy of Magnetite Plaquettes in Orgueil

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Han, J.; Zolensky, M.

    2016-01-01

    Magnetite sometimes takes the form of a plaquette - barrel-shaped stack of magnetite disks - in carbonaceous chondrites (CC) that show evidence of aqueous alteration. The asymmetric nature of the plaquettes caused Pizzarello and Groy to propose magnetite plaquettes as a naturally asymmetric mineral that can indroduce symmetry-breaking in organic molecules. Our previous synchrotron X-ray computed microtomography (SXRCT) and electron backscatter diffraction (EBSD) analyses of the magnetite plaquettes in fifteen CCs indicate that magnetite plaquettes are composed of nearly parallel discs, and the crystallographic orientations of the discs change around a rotational axis normal to the discs surfaces. In order to further investigate the nanostructures of magnetite plaquettes, we made two focused ion beam (FIB) sections of nine magnetite plaquettes from a thin section of CI Orgueil for transmission electron microscope (TEM) analysis. The X-ray spectrum imaging shows that the magnetite discs are purely iron oxide Fe3O4 (42.9 at% Fe and 57.1 at% O), which suggest that the plaquettes are of aqueous origin as it is difficult to form pure magnetite as a nebular condensate. The selected area electron diffraction (SAED) patterns acquired across the plaquettes show that the magnetite discs are single crystals. SEM and EBSD analyses suggest that the planar surfaces of the magnetite discs belong to the {100} planes of the cubic inverse spinel structure, which are supported by our TEM observations. Kerridge et al. suggested that the epitaxial relationship between magnetite plaquette and carbonate determines the magnetite face. However, according to our TEM observation, the association of magnetite with porous networks of phyllosilicate indicates that the epitaxial relationship with carbonate is not essential to the formation of magnetite plaquettes. It was difficult to determine the preferred rotational orientation of the plaquettes due to the symmetry of the cubic structure

  12. Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis

    NASA Astrophysics Data System (ADS)

    Habibi, Neda

    2015-02-01

    The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33 nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the Nsbnd CH3 functional group about 2850 cm-1 is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field.

  13. ELECTROSTATIC CHARGE ON NANO-PARTICLES ACTIVATES CNS MACROPHAGES (MICROGLIA).

    EPA Science Inventory

    Nanometer size particles carry free radical activity on their surface and can produce oxidative stress (OS)-mediated damage upon impact to target cells. The initiating event of phage cell activation (i.e., the oxidative burst) is unknown, although many proximal events have been i...

  14. Micromagnetic simulation of vortex-antivortex magnetization in permalloy nano particle

    NASA Astrophysics Data System (ADS)

    Purnama, B.; Muhammady, S.; Suharyana

    2017-02-01

    A process of vortex-antivortex magnetization reversal in a Permalloy nano particle with uniform polarity of magnetization has been investigated numerically. Micromagnetic simulation is performed using the Landau–Lifshitz–Gilbert equation. A short field pulse is applied in a film plane anti parallel to magnetization direction. Sequences of simulation of reversals mechanism are evaluated for thickness of nano particle. As the results in the case of thickness of 20 nm thin layer, magnetization reversal realizes through a creation-annihilation of Neel-Bloch wall pair. Contrarily, reversal mechanism via a creation-annihilation process of vortex-antivortex pair occurs for thickness of 60 nm thin layer. By analyzing barrier energy of the sample, we find that a maximum barrier energy reaches a threshold value (e.g., ∼ 2.6×106 erg/cm3 for Permalloy in this simulation).

  15. Peristaltic flow of a micropolar fluid with nano particles in small intestine

    NASA Astrophysics Data System (ADS)

    Akbar, Noreen Sher; Nadeem, S.

    2013-12-01

    The present article analyzed the peristaltic flow of a nanofluid in a uniform tube for micropolar fluid. The governing equations for proposed model are developed in cylindrical coordinates system. The flow is discussed in a wave frame of reference moving with velocity of the wave c. Under the assumptions of longwave length the reduced coupled nonlinear differential equations of momentum, energy, and concentrations are solved by Homotopy perturbation method is used to get the solutions for velocity, temperature, nano particle, microrotation component. The solutions consists Brownian motion number N b, thermophoresis number N t, local temperature Grashof number B r and local nano particle Grashof number G r . The effects of various parameters involved in the problem are investigated for pressure rise, pressure gradient, temperature and concentration profile. Five different waves are taken into account for analysis. Streamlines have been plotted at the end of the article.

  16. Effects on Fuel Consumption and Diesel Engine Deposits from Nano-Particle Oil Additive

    DTIC Science & Technology

    2010-07-01

    Products HTBCT High Temperature Benchtop Corrosion Test HwFET Highway Fuel Economy Test IF Inorganic Fullerene JP-8 A kerosene based jet fuel lbs...engine crankcase lubricants at the request of TARDEC. This additive contains inorganic fullerene -like (IF) nano- particles of WS2 which were claimed...volume and hardness change are shown in Table 4 with MIL-PRF-46167D specified limits. Table 4: Seal Compatibility Test Results Material Property

  17. Neuroprotective effect of curcumin-loaded lactoferrin nano particles against rotenone induced neurotoxicity.

    PubMed

    Bollimpelli, V Satish; Kumar, Prashant; Kumari, Sonali; Kondapi, Anand K

    2016-05-01

    Curcumin is known to have neuroprotective role and possess antioxidant, anti-inflammatory activities. Rotenone, a flavonoid induced neurotoxicity in dopaminergic cells is being widely studied in Parkinson's Disease (PD) research. In the present study, curcumin loaded lactoferrin nano particles prepared by sol-oil chemistry were used to protect dopaminergic cell line SK-N-SH against rotenone induced neurotoxicity. These curcumin loaded nano particles were of 43-60 nm diameter size and around 100 nm hydrodynamic size as assessed by transmission electron microscopy, atomic force microscopy and dynamic light scattering analysis respectively. The encapsulation efficiency was 61.3% ± 2.4%. Cellular uptake of curcumin through these nano particles was confirmed by confocal imaging and spectrofluorimetric analysis. The curcumin loaded lactoferrin nanoparticles showed greater intracellular drug uptake, sustained retention and greater neuroprotection than soluble counterpart. Neuroprotective activity was characterized through viability assays and by estimating ROS levels. Furthermore rotenone induced PD like features were characterized by decrease in tyrosine hydroxylase expression and increase in α-synuclein expression. Taken together curcumin loaded lactoferrin nanoparticles could be a promising drug delivery strategy against neurotoxicity in dopaminergic neurons.

  18. Advances and patents about grinding equipments with nano-particle jet minimum quantity lubrication.

    PubMed

    Jia, Dongzhou; Li, Changhe; Wang, Sheng; Zhang, Qiang; Hou, Yali

    2014-01-01

    In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques that can significantly improve both environmentally conscious and energy saving and costeffective sustainable grinding fluid alternatives. Among them, one patent is about a controllable nano-fluids jet MQL grinding system based on electrostatic atomization. Using the principle of electrostatics, it can achieve the control of droplet transfer by charging the sprayed droplets. This system can improve the uniformity of the droplet spectrum, liquid deposition efficiency and effective utilization of liquid. It can also effectively control the movement patterns of the droplets, thereby reducing the pollution of the environment and providing better health protection for workers. Although researchers accomplished profound and systematic studies on MQL, especially on nano-particles jet MQL. It can solve the shortage of MQL in cooling performance, greatly improve the working environment, save energy and reduce costs to achieve a low-carbon manufacturing. The unique lubricating performance and tribological property of solid nano-particles form nano-particle shearing films at the grinding wheel/workpiece interface, which can enhance the lubricating performance of MQL grinding. Existing studies on MQL grinding equipments, however, cannot meet the needs of the technological development. Therefore, our research provided a general introduction of the latest patients and research progress of nanoparticles jet MQL grinding equipments presented by the research team from Qingdao Technological University.

  19. Effect of Silver Nano-particles on Tensile Strength of Acrylic Resins

    PubMed Central

    Ghaffari, Tahereh; Hamedi-rad, Fahimeh

    2015-01-01

    Background and aims. Polymethyl methacrylate (PMMA) is widely used for the fabrication of removable prostheses. Silver nano-particles (AgNps) have been added to PMMA because of their antimicrobial properties, but their effect on the mechanical properties of PMMA is unknown. The aim of this study was to investigate the effects of AgNps on the tensile strength of PMMA. Materials and methods. For this study, 12 specimens were prepared and divided into two groups. Group 1 included PMMA without AgNps and group 2 included PMMA mixed with 5 wt% of AgNps. Tensile strength of the specimens was measured by Zwick Z100 apparatus. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. This study showed that the mean tensile strength of PMMA in group 2 was significantly lower than that in group 1. Therefore, the tensile strength decreased significantly after incorporation of silver nano-particles. Conclusion. Within the limitations of this study, tensile strength of acrylic resin specimens was influenced by silver nano-particles. PMID:25973153

  20. Evaluation of thermo responsive magnetic nano-particles for high- Tc SQUID bio application

    NASA Astrophysics Data System (ADS)

    Tanaka, S.; Toriyabe, C.; Torii, Y.; Hatsukade, Y.; Eki, T.; Katsura, S.; Ohnishi, N.; Wan, J.; Yang, S.; Zhang, Y.

    2007-10-01

    Immunoassay or detection of biological molecules using a high sensitive SQUID and magnetic nano-particles as labeling has been recently proposed. In this method, mostly a few particles are labeled on an antibody or biological molecules. If it is possible to give much more magnetic particles to the antibody, sensitivity must notably increase. We propose the use of thermo responsive magnetic nano-particles, which can agglutinate and disperse by themselves associated with temperature. As a preliminary experiment, we investigated the properties of thermo responsive nano-particles made of Fe3O4. By detailed study on the particles using an analyzer for a distribution of particle's outer dimension in aqueous liquid, it was found that the dimension increased with temperature above 25°, and became 400 nm at 30.5°. Magnetic measurements of the particles at different conditions using high-Tc SQUID have been done. The results suggested that the particles must be dried by heat before magnetic measurement to enhance the signal from the particles.

  1. Improved transmission method for measuring the optical extinction coefficient of micro/nano particle suspensions.

    PubMed

    Li, X C; Zhao, J M; Wang, C C; Liu, L H

    2016-10-10

    Extinction coefficients are fundamental for analyzing radiative transport in micro/nano particle suspensions. In the traditional transmission method for measuring the extinction coefficient of particles in a cuvette, a reference system is used to compensate for the influence of the cuvette and base fluid. However, the multiple reflections and refractions between the air-glass and liquid-glass interfaces cannot be sufficiently eliminated by using the reference system, and the induced measurement error increases significantly with increasing difference in refractive index between the two neighboring media at these interfaces. In this paper, an improved transmission method is proposed to measure the extinction coefficient of micro/nano particles. The extinction coefficient of the particles is determined based on an optical model, taking into account the multiple reflection and refraction at the glass-liquid interfaces. An experimental validation was conducted for suspensions with various mean particle sizes. By considering the higher-order transmission terms, the improved transmission method generally achieved high-accuracy improvement over the traditional transmission method for extinction coefficient measurement, especially for the case with a small optical thickness of particle suspensions. This work provides an alternative and more accurate way for measuring the extinction characteristics of micro/nano particle suspensions.

  2. Synthesis and Characterization of Cholesterol Nano Particles by Using w/o Microemulsion Technique

    NASA Astrophysics Data System (ADS)

    Vyas, Poorvesh M.; Vasant, Sonal R.; Hajiyani, Rakesh R.; Joshi, Mihir J.

    2010-10-01

    Cholesterol is one of the most abundant and well known steroids in the animal kingdom. Cholesterol rich micro-emulsions and nano-emulsions are useful for the treatment of breast cancer and gynecologic cancers. The nano particles of cholesterol and other pharmaceutically important materials have been reported. In the present investigation, the nano particles of cholesterol were synthesized by direct precipitation technique using triton X-100/water/n-butanol micro-emulsion. The average particle size of cholesterol nano particles was estimated by applying Scherrer's formula to the powder X-ray diffraction pattern, which was found to be 22 nm. The nanoparticles of cholesterol were observed by using TEM and the particle size was found within the range from 15 nm-31 nm. The distribution of particle size was studied through DLS. The nanoparticles of cholesterol were characterized by using FT-IR spectroscopy and the force constant was also calculated for O-H, C-H and C-O bonds. The thermal response of nanoparticles of cholesterol was studied by TGA, which showed that the nanoparticles were stable up to 200 °C and then decomposed. Kinetic and thermodynamic parameters of decomposition process were also calculated by applying Coats and Redfern formula to thermo-gram.

  3. Immobilized molybdenum-thiosemicarbazide Schiff base complex on the surface of magnetite nanoparticles as a new nanocatalyst for the epoxidation of olefins

    NASA Astrophysics Data System (ADS)

    Mohammadikish, M.; Masteri-Farahani, M.; Mahdavi, S.

    2014-03-01

    In this work, a new magnetically recoverable nanocatalyst was developed by immobilization of thiosemicarbazide ligand on the surface of silica coated magnetite nanoparticles (SCMNPs) through Schiff base condensation and followed complexation with MoO2(acac)2. Characterization of the prepared nanocatalyst was performed with different physicochemical methods such as Fourier transform infrared (FT-IR) and atomic absorption spectroscopies, X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The prepared catalyst catalyzed the epoxidation of olefins and allyl alcohols with tert-butyl hydroperoxide (TBHP) and cumene hydroperoxide (CHP) quantitatively with excellent selectivity toward the corresponding epoxides under mild reaction conditions.

  4. Effects of Natural Organic Matter on Stability, Transport and Deposition of Engineered Nano-particles in Porous Media

    EPA Science Inventory

    The interaction of nano-particles and organic substances, like natural organic matter, could have significant influence on the fate, transport and bioavailability of toxic substances. Natural organic matter (NOM) is a mixture of chemically complex polyelectrolytes with varying m...

  5. One step facile synthesis of ferromagnetic magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Suppiah, Durga Devi; Abd Hamid, Sharifah Bee

    2016-09-01

    The ferromagnetic properties of magnetite (Fe3O4) were influenced by the nanoparticle size, hence importance were given to the synthesis method. This paper clearly shows that magnetite nanoparticles were successfully synthesized by employing one step controlled precipitation method using a single salt (Iron(II) sulfate) iron precursor. The acquired titration curve from this method provides vital information on the possible reaction mechanism leading to the magnetite (Fe3O4) nanoparticles formation. Goethite (α-FeOOH) was obtained at pH 4, while the continuous addition of hydroxyl ions (OH-) forms iron hydroxides (Fe(OH)2). This subsequently reacts with the goethite, producing magnetite (Fe3O4) at pH 10. Spectroscopy studies validate the magnetite phase existence while structural and morphology analysis illustrates cubic shaped magnetite with an average size of 35 nm was obtained. The synthesized magnetite might be superparamagnetic though lower saturation magnetization (67.5 emu/g) measured at room temperature as compared to bulk magnetite. However the nanoparticles surface anisotropy leads to higher remanence (12 emu/g) and coercivity (117.7 G) making the synthesized magnetite an excellent candidate to be utilized in recording devices. The understanding of the magnetite synthesis mechanism can not only be used to achieve even smaller magnetite nanoparticles but also to prepare different types of iron oxides hydroxides using different iron precursor source.

  6. Characterization of multiphoton emission from aggregated gold nano particles

    NASA Astrophysics Data System (ADS)

    Eguchi, Akira; Lu, Phat; Kim, Youngsik; Milster, Tom D.

    2016-09-01

    Although gold nanoparticles (GNPs) are promising probes for biological imaging because of their attracting optical properties and bio-friendly nature, properties of the multi-photon (MP) emission from GNP aggregates produced by a short-wave infrared (SWIR) laser have not been examined. In this paper, characterization of MP emission from aggregated 50 nm GNPs excited by a femtosecond (fs) laser at 1560 nm is discussed with respect to aggregate structures. The key technique in this work is single particle spectroscopy. A pattern matching technique is applied to correlate MP emission and SEM images, which includes an optimization processes to maximize cross correlation coefficients between a binary microscope image and a binary SEM image with respect to xy displacement, image rotation angle, and image magnification. Once optimization is completed, emission spots are matched to the SEM image, which clarifies GNP ordering and emission properties of each aggregate. Correlation results showed that GNP aggregates have stronger MP emission than single GNPs. By combining the pattern matching technique with spectroscopy, MP emission spectrum is characterized for each GNP aggregate. A broad spectrum in the visible region and near infrared (NIR) region is obtained from GNP dimers, unlike previously reported surface plasmon enhanced emission spectrum.

  7. Magnetite pollution nanoparticles in the human brain

    NASA Astrophysics Data System (ADS)

    Maher, Barbara A.; Ahmed, Imad A. M.; Karloukovski, Vassil; MacLaren, Donald A.; Foulds, Penelope G.; Allsop, David; Mann, David M. A.; Torres-Jardón, Ricardo; Calderon-Garciduenas, Lilian

    2016-09-01

    Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683-7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <˜200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health.

  8. Magnetite pollution nanoparticles in the human brain

    PubMed Central

    Maher, Barbara A.; Karloukovski, Vassil; MacLaren, Donald A.; Foulds, Penelope G.; Allsop, David; Mann, David M. A.; Torres-Jardón, Ricardo; Calderon-Garciduenas, Lilian

    2016-01-01

    Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683–7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <∼200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health. PMID:27601646

  9. Magnetite pollution nanoparticles in the human brain.

    PubMed

    Maher, Barbara A; Ahmed, Imad A M; Karloukovski, Vassil; MacLaren, Donald A; Foulds, Penelope G; Allsop, David; Mann, David M A; Torres-Jardón, Ricardo; Calderon-Garciduenas, Lilian

    2016-09-27

    Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683-7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <∼200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health.

  10. Using graphene nano-particle embedded in photonic crystal fiber for evanescent wave mode-locking of fiber laser.

    PubMed

    Lin, Yung-Hsiang; Yang, Chun-Yu; Liou, Jia-Hong; Yu, Chin-Ping; Lin, Gong-Ru

    2013-07-15

    A photonic crystal fiber (PCF) with high-quality graphene nano-particles uniformly dispersed in the hole cladding are demonstrated to passively mode-lock the erbium-doped fiber laser (EDFL) by evanescent-wave interaction. The few-layer graphene nano-particles are obtained by a stabilized electrochemical exfoliation at a threshold bias. These slowly and softly exfoliated graphene nano-particle exhibits an intense 2D band and an almost disappeared D band in the Raman scattering spectrum. The saturable phenomena of the extinction coefficient β in the cladding provides a loss modulation for the intracavity photon intensity by the evanescent-wave interaction. The evanescent-wave mode-locking scheme effectively enlarges the interaction length of saturable absorption with graphene nano-particle to provide an increasing transmittance ΔT of 5% and modulation depth of 13%. By comparing the core-wave and evanescent-wave mode-locking under the same linear transmittance, the transmittance of the graphene nano-particles on the end-face of SMF only enlarges from 0.54 to 0.578 with ΔT = 3.8% and the modulation depth of 10.8%. The evanescent wave interaction is found to be better than the traditional approach which confines the graphene nano-particles at the interface of two SMF patchcords. When enlarging the intra-cavity gain by simultaneously increasing the pumping current of 980-nm and 1480-nm pumping laser diodes (LDs) to 900 mA, the passively mode-locked EDFL shortens its pulsewidth to 650 fs and broadens its spectral linewidth to 3.92 nm. An extremely low carrier amplitude jitter (CAJ) of 1.2-1.6% is observed to confirm the stable EDFL pulse-train with the cladding graphene nano-particle based evanescent-wave mode-locking.

  11. Experimental Deformation of Magnetite

    NASA Astrophysics Data System (ADS)

    Till, J. L.; Rybacki, E.; Morales, L. F. G.

    2015-12-01

    Magnetite is an important iron ore mineral and the most prominent Fe-oxide phase in the Earth's crust. The systematic occurrence of magnetite in zones of intense deformation in oceanic core complexes suggests that it may play a role in strain localization in some silicate rocks. We performed a series of high-temperature deformation experiments on synthetic magnetite aggregates and natural single crystals to characterize the rheological behavior of magnetite. As starting material, we used fine-grained magnetite powder that was hot isostatically pressed at 1100°C for several hours, resulting in polycrystalline material with a mean grain size of around 40 μm and containing 3-5% porosity. Samples were deformed to 15-20% axial strain under constant load (approximating constant stress) conditions in a Paterson-type gas apparatus for triaxial deformation at temperatures between 900 and 1100°C and 300 MPa confining pressure. The aggregates exhibit typical power-law creep behavior. At high stresses, samples deformed by dislocation creep exhibit stress exponents close to 3, revealing a transition to near-Newtonian creep with stress exponents around 1.3 at lower stresses. Natural magnetite single crystals deformed at 1 atm pressure and temperatures between 950°C and 1150 °C also exhibit stress exponents close to 3, but with lower flow stresses and a lower apparent activation energy than the aggregates. Such behavior may result from the different oxygen fugacity buffers used. Crystallographic-preferred orientations in all polycrystalline samples are very weak and corroborate numerical models of CPO development, suggesting that texture development in magnetite may be inherently slow compared with lower symmetry phases. Comparison of our results with experimental deformation data for various silicate minerals suggests that magnetite should be weaker than most silicates during ductile creep in dry igneous rocks.

  12. Forced vibration of two coupled carbon nanotubes conveying lagged moving nano-particles

    NASA Astrophysics Data System (ADS)

    Lü, Lei; Hu, YuJin; Wang, XueLin

    2015-04-01

    The transverse deflections of the nano-tubes are important issues in engineering applications. However, the researches on the deflection suppression are still insufficient. This paper focused on the investigation of the transverse vibration of double carbon-nano-tubes (DCNTs) which were coupled through elastic medium. Both tubes were conveying moving nano-particles and their ends were simply supported. The system equations were discretized by applying Galerkin expansion method, and numerical solutions were obtained. Several system parameters were studied to investigate the dynamics of the tubes. The results indicated that, because of the lag, the maximum transverse deflections of both coupled tubes can be reduced.

  13. Thermal treatment of magnetite nanoparticles

    PubMed Central

    Wykowska, Urszula; Satula, Dariusz; Nordblad, Per

    2015-01-01

    Summary This paper presents the results of a thermal treatment process for magnetite nanoparticles in the temperature range of 50–500 °C. The tested magnetite nanoparticles were synthesized using three different methods that resulted in nanoparticles with different surface characteristics and crystallinity, which in turn, was reflected in their thermal durability. The particles were obtained by coprecipitation from Fe chlorides and decomposition of an Fe(acac)3 complex with and without a core–shell structure. Three types of ferrite nanoparticles were produced and their thermal stability properties were compared. In this study, two sets of unmodified magnetite nanoparticles were used where crystallinity was as determinant of the series. For the third type of particles, a Ag shell was added. By comparing the coated and uncoated particles, the influence of the metallic layer on the thermal stability of the nanoparticles was tested. Before and after heat treatment, the nanoparticles were examined using transmission electron microscopy, IR spectroscopy, differential scanning calorimetry, X-ray diffraction and Mössbauer spectroscopy. Based on the obtained results, it was observed that the fabrication methods determine, to some extent, the sensitivity of the nanoparticles to external factors. PMID:26199842

  14. Printed UHF RFID antennas with high efficiencies using nano-particle silver ink.

    PubMed

    Lee, Yongshik; Kim, Chung Hwan; Shin, Dong-Youn; Kim, Young Gook

    2011-07-01

    One of the most popular targets of conductive ink technology is to print RFID tag antennas. However, the printed RFID antennas, manufactured by conductive silver ink which is generally based on microsized silver particles, have lower conductivity and consequently lower radiation efficiency than those by conventional copper etching method. This work demonstrates nano-particle conductive silver ink that is capable of printing UHF RFID antennas with improved radiation efficiency. Compared with commercial micro-particle silver ink, the solid content of metal is much higher in the proposed nanoparticle silver ink, leading to better electrical properties. Two types of dipole antennas are printed with the proposed nano-particle as well as with commercial micro-particle inks. Also, the same antennas are fabricated by copper etching. With these conductive inks, a straight and a meandered dipole antennas are fabricated and their radiation efficiencies are measured with the Wheeler cap method. Experimental results show that the radiation efficiencies of the antennas based on nanoparticle silver ink are superior to those printed with the micro-particle silver ink, and are comparable to those of popular copper antennas.

  15. A remark on nano-particle stability of cement C-S-H gel

    NASA Astrophysics Data System (ADS)

    Ficker, Tomáš; Len, Adél; Martišek, Dalibor

    2011-04-01

    Hydrated pastes of ordinary Portland cement prepared with different water-to-cement ratios were investigated by using the small-angle neutron scattering technique in the region of Q ∈ (0.0045, 0.11) Å-1. Samples of cement pastes were subjected to non-standard hydration conditions using a mix with D2O, low RH, and water-to-cement ratios spread over a very wide interval (0.4; 1.4). The investigation was focused on testing the structural stability of nano-metric particles in the cement C-S-H gel. Owing to the high structural stability of these nano-particles, their average diameter might be used as a microscopic parameter characterizing the nano-metric structure of C-S-H gels. The average diameter of the nano-particles of the studied ordinary Portland cement CEMI 42.5 R-SC was found to be close to the value of 4.2 nm and independent of the water-to-cement ratios.

  16. Effect of temperature gradient on zinc oxide nano particles synthesized at low reaction temperatures

    NASA Astrophysics Data System (ADS)

    Koutu, Vaibhav; Shastri, Lokesh; Malik, M. M.

    2017-03-01

    Zinc oxide samples were synthesized at different reaction temperatures (70 °C–110 °C) by surfactant-free co-precipitation method using temperature gradient. Formation of hexagonal wurtzite structure of the ZnO samples is confirmed from x-ray diffraction (XRD) studies. This study further suggests reduction in crystallite size from 33 nm to 24 nm with increase in reaction temperature which is reconfirmed by field emission scanning electron microscopy (FE-SEM). Optical spectroscopy studies of these samples show significant peak shift towards higher energy with maximum photoluminescence (PL) emissions between 390 nm to 575 nm region of the visible spectrum. This evident inverse relationship between optical properties of ZnO nano particles and reaction temperature may be attributed to the temperature gradient causing rapid nucleation during the synthesis process. With these notable properties this study suggests that, ZnO nano particles may be useful for making Nano electronic devices, Sensors, Nano medicines, GATE Dielectrics, Photovoltaic devices etc.

  17. Size Control of ZnO Nano-particles Formed via Thermal-Decomposition Route

    NASA Astrophysics Data System (ADS)

    Zhang, L. Z.; Yi, M. G.; Xiang, L.; Wang, B. Y.

    2010-11-01

    ZnO nano-particles with a particle size of 30-60 nm were fabricated by thermal decomposition of the basic zinc carbonate (2ZnCO3ṡ3Zn(OH)2ṡH2O) precursor at 400-600° C for 1.0-2.0 h, using ZnSO4 and Na2CO3 as the reactants. The particle size of ZnO was connected with the sintering temperature and procedure. The increase of temperature from 300° C to 600° C led to the increase of the crystallinity and the particle size of ZnO. Compared with the one-step sintering, the multi-step sintering favored the formation of dispersive ZnO nano-particles with smaller sizes. The presence of minor amount of sodium dodecyl sulfate (SDS, C12H25NaO4S) inhibited the growth and the agglomeration of the ZnO particles, reducing the primary particle size from 60-100 nm to 30-60 nm.

  18. Enhanced selectivity and capacity of clinoptilolite for Cd2+ removal from aqueous solutions by incorporation of magnetite nanoparticles and surface modification with cysteine.

    PubMed

    Sharifi, Masumeh; Baghdadi, Majid

    2016-01-01

    In this study, magnetic zeolite (MZ) nanocomposite modified with cysteine was developed in order to enhance selectivity and capacity of clinoptilolite for cadmium ion. The prepared MZ nanocomposite is containing clinoptilolite and magnetite nanoparticles with weight ratio of 3:1. The synthesized nanocomposite was characterized by transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. Surface modification was confirmed by Fourier transform infrared spectrometer. Experiments were carried out to find the optimum conditions for modification of clinoptilolite and to investigate the effective parameters (pH, adsorbent dosage, contact time, and temperature) on the adsorption of Cd(2+) ion by modified clinoptilolite. The results showed enhanced selectivity of modified MZ in the presence of other naturally occurring cations (Na(+), K(+), Ca(2+) and Mg(2+)) and ammonium. Kinetic and equilibrium data were well fitted by a pseudo second-order and Langmuir model, respectively, with high correlation coefficients. The maximum adsorption capacities of the modified and non-modified clinoptilolite were found to be 20.0 mg/g and 5.2 mg/g, respectively. Thermodynamic parameters revealed that the adsorption process is spontaneous and endothermic under studied conditions.

  19. Synthesis and characterization of magnetite/silver/antibiotic nanocomposites for targeted antimicrobial therapy.

    PubMed

    Ivashchenko, Olena; Lewandowski, Mikołaj; Peplińska, Barbara; Jarek, Marcin; Nowaczyk, Grzegorz; Wiesner, Maciej; Załęski, Karol; Babutina, Tetyana; Warowicka, Alicja; Jurga, Stefan

    2015-10-01

    The article is devoted to preparation and characterization of magnetite/silver/antibiotic nanocomposites for targeted antimicrobial therapy. Magnetite nanopowder was produced by thermochemical technique; silver was deposited on the magnetite nanoparticles in the form of silver clusters. Magnetite/silver nanocomposite was investigated by XRD, SEM, TEM, AFM, XPS, EDX techniques. Adsorptivity of magnetite/silver nanocomposite towards seven antibiotics from five different groups was investigated. It was shown that rifampicin, doxycycline, ceftriaxone, cefotaxime and doxycycline may be attached by physical adsorption to magnetite/silver nanocomposite. Electrostatic surfaces of antibiotics were modeled and possible mechanism of antibiotic attachment is considered in this article. Raman spectra of magnetite, magnetite/silver and magnetite/silver/antibiotic were collected. It was found that it is difficult to detect the bands related to antibiotics in the magnetite/silver/antibiotic nanocomposite spectra due to their overlap by the broad carbon bands of magnetite nanopowder. Magnetic measurements revealed that magnetic saturation of the magnetite/silver/antibiotic nanocomposites decreased on 6-19 % in comparison with initial magnetite nanopowder. Pilot study of antimicrobial properties of the magnetite/silver/antibiotic nanocomposites were performed towards Bacillus pumilus.

  20. Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles.

    PubMed

    Tóth, Ildikó Y; Szekeres, Márta; Turcu, Rodica; Sáringer, Szilárd; Illés, Erzsébet; Nesztor, Dániel; Tombácz, Etelka

    2014-12-30

    Magnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments, and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-vis (UV-visible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection), and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering, and FTIR-ATR results revealed that, prior to polymerization, the GA monomers became oxidized to poly(carboxylic acid)s due to ring opening while Fe(3+) ions reduced to Fe(2+). Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property, and biomedical applicability of the particles will be published.

  1. Support vector machine to predict diesel engine performance and emission parameters fueled with nano-particles additive to diesel fuel

    NASA Astrophysics Data System (ADS)

    Ghanbari, M.; Najafi, G.; Ghobadian, B.; Mamat, R.; Noor, M. M.; Moosavian, A.

    2015-12-01

    This paper studies the use of adaptive Support Vector Machine (SVM) to predict the performance parameters and exhaust emissions of a diesel engine operating on nanodiesel blended fuels. In order to predict the engine parameters, the whole experimental data were randomly divided into training and testing data. For SVM modelling, different values for radial basis function (RBF) kernel width and penalty parameters (C) were considered and the optimum values were then found. The results demonstrate that SVM is capable of predicting the diesel engine performance and emissions. In the experimental step, Carbon nano tubes (CNT) (40, 80 and 120 ppm) and nano silver particles (40, 80 and 120 ppm) with nanostructure were prepared and added as additive to the diesel fuel. Six cylinders, four-stroke diesel engine was fuelled with these new blended fuels and operated at different engine speeds. Experimental test results indicated the fact that adding nano particles to diesel fuel, increased diesel engine power and torque output. For nano-diesel it was found that the brake specific fuel consumption (bsfc) was decreased compared to the net diesel fuel. The results proved that with increase of nano particles concentrations (from 40 ppm to 120 ppm) in diesel fuel, CO2 emission increased. CO emission in diesel fuel with nano-particles was lower significantly compared to pure diesel fuel. UHC emission with silver nano-diesel blended fuel decreased while with fuels that contains CNT nano particles increased. The trend of NOx emission was inverse compared to the UHC emission. With adding nano particles to the blended fuels, NOx increased compared to the net diesel fuel. The tests revealed that silver & CNT nano particles can be used as additive in diesel fuel to improve complete combustion of the fuel and reduce the exhaust emissions significantly.

  2. Observation the Distribution of Titanium Dioxide Nano-particles in an Experimental Tumor Tissue by a Raman Microscope

    NASA Astrophysics Data System (ADS)

    Bibin, Andriana B.; Kume, Kyo; Tsutumi, Kotaro; Fukunaga, Yukihiro; Ito, Shinnji; Imamura, Yoshiaki; Miyoshi, Norio

    2011-12-01

    One of the most important technologies of the 21st century is nanotechnology. Many researchers will have been focusing to employ nanotechnology for medical purpose. Our team was interested in focusing to the application of titanium dioxide (TiO2), as nano-particles, for medical purpose especially drug delivery for the cancer and tumor. The administrations of TiO2 nano-particle via the oral administration of the interface layer particles into the mouse transplanted squamous-cell-carcinoma (SCC) have already conducted. Histology study and Raman spectroscope data were applied to the serial section of frozen tumor tissue in order to observe the distribution of TiO2 nano-particle within the SCC tissue. We used near infrared laser Raman microscopy system, the wavelength is 785 nm. Hematoxyline & eosin stained image and the Raman microscopy system were also used for analyzing the photodynamic therapy (PDT) with 5-ALA and TiO2-particle-sol [TiO2]-ALA-treated tumor samples. As the result, we demonstrated the distribution of TiO2, where TiO2 particles were detected to be distributed in the blood vessel at the bleeding in the SCC tumor tissue. PDT with TiO2 nano-particles that is presented in the SCC-transplanted mouse tumor model can cause the enhancement of photodynamic reaction by nano-particles. Therefore, the combinations of PDT with TiO2 nano-particles may have a possibility to be introduced to the human body in near future for diagnose and PDT treatment of the tumor.

  3. Enhancing Asphalt Binder's Rheological Behavior and Aging Susceptibility Using Nano-Particles

    NASA Astrophysics Data System (ADS)

    Walters, Renaldo C.

    The life expectancy of Asphalt Binder (AB) has been negatively impacted by the harsh bombardment of UV rays. UV rays cause asphalt to oxidize faster which results in deterioration of asphalt rheological characteristics that can lead to pavement distresses. This study investigates the impact that nano-particles and bio modification have on the aging susceptibility of asphalt binder. As such, the following hypothesis was investigated: Introduction of nano particles to asphalt binder will reduce asphalt oxidation aging by increasing the inter layer spacing of the nano particles. Two nano scale materials were used for this study, nano-clay and bio-char as well as one micro scale material, silica fume. Nano-clay (Cloisite 30B) is a naturally occurring inorganic mineral. Bio-char is the waste product from bio-binder production. Bio-binder is produced from swine manure using a thermochemical conversion process. This process is then followed by a filtration procedure where the bio-char is produced. Chemical and physical properties of bio-char showed a significant presence of carbon which could in turn reduce the rate of asphalt oxidation. Silica Fume is an ultra-fine powder collected as a by-product of silicon and ferrosilicon alloy production and consists of spherical particles. In this study several mixtures are designed and evaluated using RV testing (Rotational Viscometer), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Nano-clay is blended at 2% and 4% by weight of dry mass, with and without bio-binder (5% by weight of dry mass). Bio-char is grinded to nano scale and added to the virgin asphalt binder (PG 64-22) at 2%, 5% and 10% by weight of dry mass. Silica Fume is added to virgin asphalt binder (PG 64-22) at 2%, 4% and 8% by weight of dry mass. The optimum percent of nano scale material that is added to virgin asphalt binder is expected to reduce aging susceptibility of asphalt binder, extending its service life.

  4. Stabilization and encapsulation of magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Kawni, Issmat Al; Garcia, Ricardo; Youssef, Sami; Abboud, Maher; Podlecki, Jean; Habchi, Roland

    2016-12-01

    The goal is to stabilize magnetite nanoparticles (NPs) in order to prepare them for encapsulation and to obtain a core-shell structure. Magnetite NPs were obtained by a co-precipitation method and then treated with different stabilizing agents in order to get a full dispersion in an aqueous medium. The dispersed particles were then coated with silica using a TEOS solution. The samples were characterized by Raman spectroscopy, TEM, EDX analysis, and FTIR measurements. The particles are the basis of a core-shell structure where a potential polymer or drug could be anchored on the surface.

  5. Development of CMC hydrogels loaded with silver nano-particles for medical applications.

    PubMed

    Hebeish, Ali; Hashem, M; El-Hady, M M Abd; Sharaf, S

    2013-01-30

    Innovative CMC-based hydrogels with great potentials for usage in medical area were principally synthesized as per two strategies .The first involved reaction of epichlorohydrin in alkaline medium containing silver nitrate to yield silver nano-particles (AgNPs)-loaded CMC hydrogel. While CMC acted as stabilizing for AgNPs, trisodium citrate was added to the reaction medium to assist CMC in establishing reduction of Ag(+) to AgNPs. The second strategy entailed preparation of CMC hydrogel which assists the in situ preparation of AgNPs under the same conditions. In both strategies, factors affecting the characterization of AgNPs-loaded CMC hydrogels were studied. Analysis and characterization of the so obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, EDX, UV-vis spectrophotometer and TEM. Antimicrobial activity of the hydrogels was examined and mechanisms involved in their synthesis were reported.

  6. Enhanced copper micro/nano-particle mixed paste sintered at low temperature for 3D interconnects

    NASA Astrophysics Data System (ADS)

    Dai, Y. Y.; Ng, M. Z.; Anantha, P.; Lin, Y. D.; Li, Z. G.; Gan, C. L.; Tan, C. S.

    2016-06-01

    An enhanced copper paste, formulated by copper micro- and nano-particles mixture, is reported to prevent paste cracking and obtain an improved packing density. The particle mixture of two different sizes enables reduction in porosity of the micro-paste and resolves the cracking issue in the nano-paste. In-situ temperature and resistance measurements indicate that the mixed paste has a lower densification temperature. Electrical study also shows a ˜12× lower sheet resistance of 0.27 Ω/sq. In addition, scanning electron microscope image analysis confirms a ˜50% lower porosity, which is consistent with the thermal and electrical results. The 3:1 (micro:nano, wt. %) mixed paste is found to have the strongest synergistic effect. This phenomenon is discussed further. Consequently, the mixed paste is a promising material for potential low temperature 3D interconnects fabrication.

  7. Molecular dynamics study of force acting on a model nano particle immersed in fluid with temperature gradient: Effect of interaction potential

    NASA Astrophysics Data System (ADS)

    Tsuji, Tetsuro; Iseki, Hirotaka; Hanasaki, Itsuo; Kawano, Satoyuki

    2016-11-01

    Thermophoresis of a nano particle in a fluid is investigated using molecular dynamics simulation. In order to elucidate effective factors on the characteristics of thermophoresis, simple models for both the fluid and the nano particle are considered, namely, the surrounding fluid consists of Lennard-Jones (LJ) particles and the model nano particle is a cluster consisting of several tens of LJ particles. Interaction between the fluid particle and the model nano particle is described by the LJ interaction potential or repulsive interaction potential with the Lorentz-Berthelot mixing rule. As a preliminary result, the effect of mass on thermophoretic force acting on the model nano particle is investigated for both interaction potentials.

  8. Modifying Si-based consolidants through the addition of colloidal nano-particles

    NASA Astrophysics Data System (ADS)

    Ksinopoulou, E.; Bakolas, A.; Moropoulou, A.

    2016-04-01

    The modification of silicon-based stone consolidants has been the subject of many scientific studies aiming to overcome the commonly reported drawbacks of these materials, such as the tendency to shrink and crack during drying. The addition of nano-particle dispersions into silica matrix has been found to enhance their effectiveness in several ways. Objective of the current research was to study the preparation of particle-modified consolidants (PMC), consisting of an ethyl silicate matrix (TEOS) loaded with colloidal silica (SiO2) nano-particles and oxide titania (TiO2) particles. The effect of the polyacrylic acid on the dispersion stability was also investigated, by varying its concentration into PMC samples. The prepared materials were allowed to dry in two different relative humidity environments and then evaluated based on their stability in the sol phase, the aggregation sizes, determined through dynamic light scattering, the % solids content and their morphological characteristics, observed via scanning electron microscopy (SEM-EDAX). Mercury intrusion porosimetry was also applied to investigate the microstructural characteristics and differences between the prepared consolidants. Significant role in the final form of the material is played by both the initial molar ratios in the mixtures, as well as the conditions where the drying and aging takes place. Based on the results, the three-component PMCs appear to be promising in stone consolidation, as they show a reduction in cracking and shrinkage during drying and a more porous network, compared with the siliceous material, or the two-component TEOS-SiO2 formulation.

  9. Development of a gold nano-particle-based fluorescent molecular beacon for detection of cystic fibrosis associated mutation.

    PubMed

    Beni, Valerio; Hayes, Karen; Lerga, Teresa Mairal; O'Sullivan, Ciara K

    2010-10-15

    Cystic fibrosis is one of the most common genetically inherited diseases in Northern Europe, consisting of an inherited defect of chloride transport in the epithelium. Of the several mutations related to CF, the ΔF508 mutation occurs in ca. 70% of the cases. In this work the use of a gold nano-particle supported fluorescence molecular beacon was investigated as an optical sensing platform for the detection of the ΔF508 cystic fibrosis associated mutation. Different parameters such as molecular beacon design, Au nano-particle size, molecular beacon-nano-particle conjugation protocol, molecular beacon loading as well as experimental conditions were evaluated. A 31-base long molecular beacon, containing a 15-base recognition sequence specific for the mutant target, was linked via a thiol modified poly thymine linker (10 bases long) to a 13 nm gold nano-particle and was exposed to mutant and wild type targets, and a clear differentiation was achieved at target concentrations as low as 1 nM.

  10. Near-infrared absorbing polymer nano-particle as a sensitive contrast agent for photo-acoustic imaging.

    PubMed

    Aoki, Hiroyuki; Nojiri, Mayumi; Mukai, Rieko; Ito, Shinzaburo

    2015-01-07

    Polymer nano-particles (PNPs) with a near-infrared (NIR) light absorption were prepared by the nano-emulsion method to develop contrast agents for photo-acoustic (PA) imaging. The PNP containing silicon naphthalocyanine showed a high absorption coefficient up to 10(10) M(-1) cm(-1). This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grüneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10(-13) M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging.

  11. Cellular uptake of beta-carotene from protein stabilized solid lipid nano-particles prepared by homogenization-evaporation method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using a homogenization-evaporation method, beta-carotene (BC) loaded nano-particles were prepared with different ratios of food-grade sodium caseinate (SC), whey protein isolate (WPI), or soy protein isolate (SPI) to BC and evaluated for their physiochemical stability, in vitro cytotoxicity, and cel...

  12. Synthesis and spectroscopic investigations of iron oxide nano-particles for biomedical applications in the treatment of cancer cells

    NASA Astrophysics Data System (ADS)

    Atta, Aly H.; El-ghamry, Mosad A.; Hamzaoui, Adel; Refat, Moamen S.

    2015-04-01

    Recently, upon the great importance of synthesized nano-particles especially ferric oxides on medicinal applications, these nano-particles have been prepared here using friendly and low cost biological precursors moieties via a thermal decomposition method. The Fe2O3 nano-particles preparation method is based on thermal degradation of ferric complexes of hippuric acid, itaconic acid, or tyrosine amino acid at 600 °C. The used precursors were characterized by several characterization techniques such as microanalysis, conductance, infrared spectra, electronic spectra, and thermogravimetric (TG/DTG). The calcinations stages were identified from the thermogravimetric analyses of ferric complexes. The narrow size distribution in nano-scale range for the Fe2O3 crystals have been studied using X-ray powder diffraction (XRD), scanning electron microscope (SEM), X-ray energy dispersive spectrometer (EDX) and transmission electron microscopy (TEM) analyzer. XRD data indicate that a single phase Fe2O3 nano-particles are obtained with particle size ranging from 20 to 60 nm. The cytotoxic activity of the Fe2O3 nanoparticles was tested against the breast carcinoma cells (MCF-7 cell line). The results of inhibitory concentration fifty (IC50) were existed within the 3.10-3.81 μg limit.

  13. Fe atom exchange between aqueous Fe2+ and magnetite.

    PubMed

    Gorski, Christopher A; Handler, Robert M; Beard, Brian L; Pasakarnis, Timothy; Johnson, Clark M; Scherer, Michelle M

    2012-11-20

    The reaction between magnetite and aqueous Fe(2+) has been extensively studied due to its role in contaminant reduction, trace-metal sequestration, and microbial respiration. Previous work has demonstrated that the reaction of Fe(2+) with magnetite (Fe(3)O(4)) results in the structural incorporation of Fe(2+) and an increase in the bulk Fe(2+) content of magnetite. It is unclear, however, whether significant Fe atom exchange occurs between magnetite and aqueous Fe(2+), as has been observed for other Fe oxides. Here, we measured the extent of Fe atom exchange between aqueous Fe(2+) and magnetite by reacting isotopically "normal" magnetite with (57)Fe-enriched aqueous Fe(2+). The extent of Fe atom exchange between magnetite and aqueous Fe(2+) was significant (54-71%), and went well beyond the amount of Fe atoms found at the near surface. Mössbauer spectroscopy of magnetite reacted with (56)Fe(2+) indicate that no preferential exchange of octahedral or tetrahedral sites occurred. Exchange experiments conducted with Co-ferrite (Co(2+)Fe(2)(3+)O(4)) showed little impact of Co substitution on the rate or extent of atom exchange. Bulk electron conduction, as previously invoked to explain Fe atom exchange in goethite, is a possible mechanism, but if it is occurring, conduction does not appear to be the rate-limiting step. The lack of significant impact of Co substitution on the kinetics of Fe atom exchange, and the relatively high diffusion coefficients reported for magnetite suggest that for magnetite, unlike goethite, Fe atom diffusion is a plausible mechanism to explain the rapid rates of Fe atom exchange in magnetite.

  14. Formation of nickel-doped magnetite hollow nanospheres with high specific surface area and superior removal capability for organic molecules

    NASA Astrophysics Data System (ADS)

    Li, Zhenhu; Ma, Yurong; Qi, Limin

    2016-12-01

    A strategy for the formation of magnetic Ni x Fe3-x O4 hollow nanospheres with very high specific surface areas was designed through a facile solvothermal method in mixed solvents of ethylene glycol and water in this work. The Ni/Fe ratios and the crystal phases of the Ni x Fe3-x O4 hollow nanocrystals can be readily tuned by changing the molar ratios of Ni to Fe in the precursors. An inside-out Ostwald ripening mechanism was proposed for the formation of uniform Ni x Fe3-x O4 hollow nanospheres. Moreover, the obtained Ni x Fe3-x O4 hollow nanospheres exhibited excellent adsorption capacity towards organic molecules such as Congo red in water. The maximum adsorption capacities of Ni x Fe3-x O4 hollow nanospheres for Congo red increase dramatically from 263 to 500 mg g-1 with the increase of the Ni contents (x) in Ni x Fe3-x O4 hollow nanospheres from 0.2 to 0.85. The synthesized Ni x Fe3-x O4 nanoparticles can be potentially applied for waste water treatment.

  15. Gd-DTPA Adsorption on Chitosan/Magnetite Nanocomposites

    NASA Astrophysics Data System (ADS)

    Pylypchuk, Ie. V.; Kołodyńska, D.; Kozioł, M.; Gorbyk, P. P.

    2016-03-01

    The synthesis of the chitosan/magnetite nanocomposites is presented. Composites were prepared by co-precipitation of iron(II) and iron(III) salts by aqueous ammonia in the 0.1 % chitosan solution. It was shown that magnetite synthesis in the chitosan medium does not affect the magnetite crystal structure. The thermal analysis data showed 4.6 % of mass concentration of chitosan in the hybrid chitosan/magnetite composite. In the concentration range of initial Gd-DTPA solution up to 0.4 mmol/L, addition of chitosan to magnetite increases the adsorption capacity and affinity to Gd-DTPA complex. The Langmuir and Freundlich adsorption models were applied to describe adsorption processes. Nanocomposites were characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and specific surface area determination (ASAP) methods.

  16. Influence of silver content on rifampicin adsorptivity for magnetite/Ag/rifampicin nanoparticles

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Olena; Coy, Emerson; Peplinska, Barbara; Jarek, Marcin; Lewandowski, Mikołaj; Załęski, Karol; Warowicka, Alicja; Wozniak, Anna; Babutina, Tatiana; Jurga-Stopa, Justyna; Dolinsek, Janez; Jurga, Stefan

    2017-02-01

    Magnetite nanoparticles (NPs) decorated with silver (magnetite/Ag) are intensively investigated due to their application in the biomedical field. We demonstrate that the increase of silver content on the surface of nanoparticles improves the adsorptivity of antibiotic rifampicin as well as antibacterial properties. The use of ginger extract allowed to improve the silver nucleation on the magnetite surface that resulted in an increase of silver content. Physicochemical and functional characterization of magnetite/Ag NPs was performed. Our results show that 5%-10% of silver content in magnetite/Ag NPs is already sufficient for antimicrobial properties against Streptococcus salivarius and Staphylococcus aureus. The rifampicin molecules on the magnetite/Ag NPs surface made the spectrum of antimicrobial activity wider. Cytotoxicity evaluation of the magnetite/Ag/rifampicin NPs showed no harmful action towards normal human fibroblasts, whereas the effect on human embryonic kidney cell viability was time and dose dependent.

  17. Multiple ordering in magnetite.

    NASA Technical Reports Server (NTRS)

    Cullen, J. R.; Callen, E. R.

    1973-01-01

    Results of a self-consistent band calculation of the ground-state energy and charge orderings based on a tight-binding scheme in magnetite are presented. They show that below a critical (about 2.2) value of the ratio of interatomic Coulomb energy to bandwidth the lowest energy state has no order. Between this critical value and 2.5, the preferred state is multiply ordered.

  18. Role of plant growth promoting rhizobacteria and Ag-nano particle in the bioremediation of heavy metals and maize growth under municipal wastewater irrigation.

    PubMed

    Khan, Naeem; Bano, Asghari

    2016-01-01

    The investigation evaluated the role of plant growth promoting rhizobacteria (PGPR) and Ag-nano particle on the growth and metabolism of maize irrigated with municipal wastewater (MW). Three PGPR isolated from MW were identified on the basis of 16S-rRNA gene sequence analyses as Pseudomonas sp., Pseudomonas fluorescence, and Bacillus cereus. The municipal waste water was used to irrigate the maize seeds inoculated with 3 isolated PGPR. The isolated PGPR had catalase and oxidase enzymes, solubilize insoluble bound phosphate and exhibit antifungal and antibacterial activities. The colony forming unit (cfu) of the PGPR was inhibited by Ag-nano particle, but was stimulated by the municipal wastewater. The Ag-nano particles augmented the PGPR induced increase in root area and root length. The root-shoot ratio was also changed with the Ag-nano particles. The plants irrigated with municipal wastewater had higher activities of peroxidase and catalase which were further augmented by Ag-nano particle. The Ag- nano particle application modulated level of ABA (34%), IAA (55%), and GA (82%), increased proline production (70%) and encountered oxidative stress and augmented the bioremediation potential of PGPR for Pb, Cd, and Ni. Municipal wastewater needs to be treated with PGPR and Ag nano particle prior to be used for irrigation. This aims for the better growth of the plant and enhanced bioremediation of toxic heavy metals.

  19. Chemical characterization, nano-particle mineralogy and particle size distribution of basalt dust wastes.

    PubMed

    Dalmora, Adilson C; Ramos, Claudete G; Oliveira, Marcos L S; Teixeira, Elba C; Kautzmann, Rubens M; Taffarel, Silvio R; de Brum, Irineu A S; Silva, Luis F O

    2016-01-01

    Understanding the geochemistry of basalt alteration is central to the study of agriculture systems. Various nano-minerals play an important role in the mobilization of contaminants and their subsequent uptake by plants. We present a new analytical experimental approach in combination with an integrated analytical protocol designed to study basalt alteration processes. Recently, throughout the world, ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been of great concern for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the Nova Prata mining district in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/Energy Dispersive Spectroscopy (EDS)/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM/EDS), and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3, and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition, we have identified a number of trace metals such as Cd, Cu, Cr, and Zn, that are preferentially concentrated into the finer, inhalable, dust fraction and, thus, could present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in

  20. Direct solvent induced microphase separation, ordering and nano-particles infusion of block copolymer thin films

    NASA Astrophysics Data System (ADS)

    Modi, Arvind; Sharma, Ashutosh; Karim, Alamgir

    2013-03-01

    Kinetics of block copolymer (BCP) microphase separation by thermal annealing is often a challenge to low-cost and faster fabrication of devices because of the slow ordering. Towards the objective of rapid processing and accessing desired nanostructures, we are developing methods that enable a high degree of mobility of BCP phases while maintaining phase separation conditions via control of effective interaction parameter between the blocks in BCP thin films. We study the self-assembly of PS-P2VP thin films in various solvent mixtures. While non-solvent prevents dissolution of film into the bulk solution, the good solvent penetrates the film and makes polymer chains mobile. As a result of controlled swelling and mobility of BCP blocks, solvent annealing of pre-cast BCP thin films in liquid mixture of good solvent and non-solvent is a promising method for rapid patterning of nanostructures. Interestingly, we demonstrate simultaneous BCP microphase separation and infusion of gold nano-particles into selective phase offering a wide range of application from plasmonics to nanoelectronics. University of Akron Research Foundation (UARF)

  1. Properties of micro-nano particle size admixtures of alumina at different sintering condition

    NASA Astrophysics Data System (ADS)

    Sifat, Rahin; Akter, Manira; Rashid, A. K. M. Bazlur

    2016-07-01

    Among various ceramic materials, alumina is mostly used material for its hardness and strength. There is a difference between the properties of alumina due to their different particle size. Also different holding time in the sintering temperature has effect on the sintering of alumina of different particle size. In this study, micro alumina and nano alumina were mixed in different ratios and sintered at different sintering condition to compare their mechanical properties that varied due to their different particle size distribution. In this work, conventional solid state sintering route was followed to prepare final samples. Six different particle size ratio of alumina (micro:nano= 100:0, 95:5, 90:10, 10:90, 5:95, 0:100) with a doping of 0.1% MgO were used. The sintering temperature was 1500° C but sintering condition was different. After comparing the mechanical properties, it has been observed that relatively improved properties can be obtained by increasing nano particle percentages in the micro alumina than the reverse mixture.

  2. Theory of molecule metal nano-particle interaction: Quantum description of plasmonic lasing

    SciTech Connect

    Zhang, Yuan May, Volkhard

    2015-06-14

    The recent quantum description of a few molecules interacting with plasmon excitations of a spherical metal nano-particle (MNP) as presented in the work of Zhang and May [Phys. Rev. B 89, 245441 (2014)] is extended to systems with up to 100 molecules. We demonstrate the possibility of multiple plasmon excitation and describe their conversion into far-field photons. The calculation of the steady-state photon emission spectrum results in an emission line-narrowing with an increasing number of molecules coupled to the MNP. This is considered as an essential criterion for the action of the molecule-MNP system as a nano-laser. To have exact results for systems with up to 20 molecules, we proceed as recently described by Richter et al. [Phys. Rev. B 91, 035306 (2015)] and study a highly symmetric system. It assumes an equatorial and regular position of identical molecules in such a way that their coupling is dominated by that to a single MNP dipole-plasmon excitation. Changing from the exact computation of the system’s complete density matrix to an approximate theory based on the reduced plasmon density matrix, systems with more than 100 molecules can be described. Finally, nonlinear rate equations are proposed which reproduce the mean number of excited plasmons in their dependence of the number of molecules and of the used pump rate. The second order intensity correlation function of emitted photons is related to the respective plasmon correlation function which approaches unity when the system starts lasing.

  3. Recent patents on amylose-flavor inclusion complex nano particles preparation and their application.

    PubMed

    Feng, Tao; Zhuang, Hai N; Xiao, Zuo B; Tian, Huai X

    2011-09-01

    Lipophilic and hydrophilic compounds that are solubilized in the form of nano-sized particles, or "nanoparticles", can be used in pharmacology, in the production of food additives, cosmetics, and agriculture, as well as in pet foods and veterinary products, amongst other uses. This review focuses on nanoparticles and methods for the production of soluble nanoparticles and, in particular, inclusion complexes of water-insoluble lipophilic and water-soluble hydrophilic organic materials, especially flavor compounds. The host molecule is namely V-amylose or modified starch molecule, which could form a cavity to fix or secure guest molecules. Thus, the V-amylose molecular properties and the molecular inclusion complex formation mechanism is firstly introduced, then amylose-other ingredients inclusion complex preparation and application are listed, finally amylose-flavor molecular inclusion complex preparations and its application have been overviewed. Through this review, it is concluded that amylose-small chemical molecule inclusion complexes, especially amylose-flavor inclusion complexes have a marvelous application prospect and have great significance to develop the nano-product application field. This paper reviews the recent patents on amylose-flavour inclusion complex nano particles preparation and their application.

  4. Enhanced dielectric breakdown performances of propylene carbonate modified by nano-particles under microsecond pulses

    NASA Astrophysics Data System (ADS)

    Hou, Yanpan; Zhang, Jiande; Zhang, Zicheng

    2016-06-01

    Propylene carbonate shows appealing prospects as an energy storage medium in the compact pulsed power sources because of its large permittivity, high dielectric strength, and broad operating temperature range. In this paper, TiO2 nano-particles coated with γ-aminopropyltriethoxylsilane coupling agent are homogeneously dispersed into propylene carbonate and these nano-fluids (NFs) exhibit substantially larger breakdown voltages than those of pure propylene carbonate. It is proposed that interfaces between nano-fillers and propylene carbonate matrix may provide myriad trap sites for charge carriers. The charge carriers can be easily captured at the interfaces between NFs and the electrode, resulting in an increased barrier height and suppressed charge carriers injection, and in the bulk of NFs, the charge carriers' mean free path can be greatly shortened by the scattering effect. As a result, in order for charge carriers acquiring enough energy to generate a region of low density (the bubble) and initiate breakdown in NFs, much higher applied field is needed.

  5. Eulerian flow modeling of suspensions containing interacting nano-particles: application to colloidal film drying.

    NASA Astrophysics Data System (ADS)

    Gergianakis, I.; Meireles, M.; Bacchin, P.; Hallez, Y.

    2015-11-01

    Nano-particles in suspension often experience strong non-hydrodynamic interactions (NHIs) such as electrostatic repulsions. In this work, we present and justify a flow modeling strategy adapted to such systems. Earlier works on colloidal transport in simple flows, were based on the solution of a transport equation for the colloidal volume fraction with a known fluid velocity field and a volume-fraction-dependent diffusion coefficient accounting for mass fluxes due to NHIs. Extension of this modelling to complex flows requires the coupled resolution of a momentum transport equation for the suspension velocity field. We use the framework of the Suspension Balance Model to show that in the Pe << 1 regime relevant here, the average suspension velocity field is independent of NHIs between nanoparticles , while the average fluid phase and solid phase velocity fields both always depend of the NHIs. Lastly, we apply this modelling strategy to the problem of the drying of a colloidal suspension in a micro-evaporator [Merlin et al., 2012, Soft Matter]. The influence of the effective Peclet number on the 1D/2D character of the flow is evaluated and the possible colloidal film patterning due to defaults of substrate topography is commented.

  6. Recovery of Neodymium from Aqueous Solution Using Magnetic Nano-particles

    NASA Astrophysics Data System (ADS)

    Tu, Y. J.; You, C. F.; Lo, S. C.

    2015-12-01

    This study investigates the recovery of spiked Nd from seawater media by magnetic nano-particles Fe3O4. A rapid increase of Nd recovery from 0.06 to 23.6 mg g-1 was observed when the solution pH adjusted from 2.01 to 8.18 at 298 K. A maxima Nd adsorption capacity was estimated to be 25.02 mg g-1 at 308 K and 8.18 pH. A negative change in standard free energy (ΔGo = -5.87, -6.69, -7.68 kJ mol-1 at 288, 298, and 308 K, respectively) suggests that Nd adsorption is spontaneous. The positive ΔHo value (2.42 kJ mol-1) supports its endothermic nature of the adsorption and agrees with the observed enhanced Nd adsorption at high temperatures. Besides, the positive ΔSo (10.84 J mol-1 K-1) displays that the randomness increase at the solid-solution interface during Nd adsorption. More importantly, we observed that the Nd adsorption only decreased slightly while the NaCl ionic strength increased from 0.001 to 1.0 N, implying the involvement of inner-sphere mechanism. These data indicated that the adsorbent of ferrite has a great potential in selective and fast recovery of spiked Nd from seawater matrix.

  7. Fate and effect of tire rubber ash nano-particles (RANPs) in cucumber.

    PubMed

    Moghaddasi, Sahar; Hossein Khoshgoftarmanesh, Amir; Karimzadeh, Fatholah; Chaney, Rufus

    2015-05-01

    There are growing interests on effects of nano-materials on living organisms including higher plants. No report is available on positive and negative effects of rubber ash nano-particles (RANPs) on edible plants. Recently, we reported the possibility of using waste tire rubber and rubber ash as zinc (Zn) fertilizer for plants. In this nutrient solution culture study, for the first time, root uptake and the effects of RANPs on growth and Zn, cadmium (Cd), and lead (Pb) concentration in cucumber was investigated. Various Zn levels (0, 1, 5, 25, 125mgL(-1)) were applied in the form of RANPs or ZnSO4. The root RANPs uptake was visualized by light (LA), scanning electron (SEM), and transmission electron microcopies (TEM). At all Zn levels, cucumber plants supplied with RANPs produced higher shoot and root biomass compared with those supplied with ZnSO4. In addition, the RANPs resulted in higher accumulation of Zn in cucumber tissues in comparison with ZnSO4; although phytotoxicity of Zn from ZnSO4 was greater than that from RANPs. Clear evidence of the RANPs penetration into the root cells was obtained by using SEM and TEM. Filaments of RANPs were also observed at the end of roots by LM and TEM. Further research is needed to clarify the fate of the RANPs in plant cells and their possible risks for food chain.

  8. Theory of molecule metal nano-particle interaction: Quantum description of plasmonic lasing.

    PubMed

    Zhang, Yuan; May, Volkhard

    2015-06-14

    The recent quantum description of a few molecules interacting with plasmon excitations of a spherical metal nano-particle (MNP) as presented in the work of Zhang and May [Phys. Rev. B 89, 245441 (2014)] is extended to systems with up to 100 molecules. We demonstrate the possibility of multiple plasmon excitation and describe their conversion into far-field photons. The calculation of the steady-state photon emission spectrum results in an emission line-narrowing with an increasing number of molecules coupled to the MNP. This is considered as an essential criterion for the action of the molecule-MNP system as a nano-laser. To have exact results for systems with up to 20 molecules, we proceed as recently described by Richter et al. [Phys. Rev. B 91, 035306 (2015)] and study a highly symmetric system. It assumes an equatorial and regular position of identical molecules in such a way that their coupling is dominated by that to a single MNP dipole-plasmon excitation. Changing from the exact computation of the system's complete density matrix to an approximate theory based on the reduced plasmon density matrix, systems with more than 100 molecules can be described. Finally, nonlinear rate equations are proposed which reproduce the mean number of excited plasmons in their dependence of the number of molecules and of the used pump rate. The second order intensity correlation function of emitted photons is related to the respective plasmon correlation function which approaches unity when the system starts lasing.

  9. Biopolymer nano-particles and natural nano-carriers for nano-encapsulation of phenolic compounds.

    PubMed

    Faridi Esfanjani, Afshin; Jafari, Seid Mahdi

    2016-10-01

    Phenolic compounds are major micronutrients in our diet,(1) and evidence for their role in the prevention of degenerative diseases such as cancer, inflammation and neurodegenerative diseases is emerging. The easily destruction against environment stresses and low bioavailability of phenolics are main limitations of their application. Therefore, nano-encapsulated phenolics as a fine delivery system can solve their restrictions. Polymeric nanoparticles and natural nano-carriers are one of the most effective and industrial techniques which can be used for protection and delivery of phenolics. In this review, preparation, application and characterization of polymeric based nano-capsules and natural nano-carriers for phenolics have been considered and discussed including polymeric nanoparticles, polymeric complex nanoparticles, cyclodextrins, nano-caseins, nanocrystals, electrospun nano-fibers, electro-sprayed nano-particles, and nano-spray dried particles. Our main goal was to cover the relevant recent studies in the past few years. Although a number of different types of polymeric and natural based nano-scale delivery systems have been developed, there are relatively poor quantitative understanding of their in vivo absorption, permeation and release. Also, performing toxicity experiments, residual solvent analysis and studying their biological fate during digestion, absorption, and excretion of polymeric nanoparticle and natural nano-carriers containing phenolics should be considered in future researches. In addition, future investigations could focus on application of phenolic nano-scale delivery systems in pharmaceuticals and functional foods.

  10. Investigation on Tc tuned nano particles of magnetic oxides for hyperthermia applications.

    PubMed

    Giri, Jyotsnendu; Ray, Amlan; Dasgupta, S; Datta, D; Bahadur, D

    2003-01-01

    Superparamagnetic as well as fine ferrimagnetic particles such as Fe3O4, have been extensively used in magnetic field induced localized hyperthermia for the treatment of cancer. The magnetic materials with Curie temperature (Tc) between 42 and 50 degrees C, with sufficient biocompatibility are the best candidates for effective treatment such that during therapy it acts as in vivo temperature control switch and thus over heating could be avoided. Ultrafine particles of substituted ferrite Co(1-a)Zn(a)Fe2O4 and substituted yttrium-iron garnet Y3Fe(5-x)Al(x)O12 have been prepared through microwave refluxing and citrate-gel route respectively. Single-phase compounds were obtained with particle size below 100 nm. In order to make these magnetic nano particles biocompatible, we have attempted to coat these above said composition by alumina. The coating of alumina was done by hydrolysis method. The coating of hydrous aluminium oxide has been done over the magnetic particles by aging the preformed solid particles in the solution of aluminium sulfate and formamide at elevated temperatures. In vitro study is carried out to verify the innocuousness of coated materials towards cells. In vitro biocompatibility study has been carried out by cell culture method for a period of three days using human WBC cell lines. Study of cell counts and SEM images indicates the cells viability/growth. The in vitro experiments show that the coated materials are biocompatible.

  11. The effect of acid–base clustering and ions on the growth of atmospheric nano-particles

    SciTech Connect

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, Joao; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Maatta, Oona; Laaksonen, Ari; Lawler, Michael J.; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K.; Onnela, Antti; Petaja, Tuukka; Praplan, Arnaud; Rissanen, Matti P.; Ruuskanen, Taina; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N.; Trostl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamaki, Hanna; Vrtala, Aron E.; Wagner, Paul E.; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M.; Virtanen, Annele; Donahue, Neil M.; Carslaw, Kenneth S.; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R.; Kulmala, Markku

    2016-05-20

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. Furthermore, we bring these observations into a coherent framework and discuss their significance in the atmosphere.

  12. The effect of acid-base clustering and ions on the growth of atmospheric nano-particles

    NASA Astrophysics Data System (ADS)

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J.; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K.; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P.; Ruuskanen, Taina; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N.; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E.; Wagner, Paul E.; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M.; Virtanen, Annele; Donahue, Neil M.; Carslaw, Kenneth S.; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R.; Kulmala, Markku

    2016-05-01

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.

  13. Dose limited reliability of quantitative annular dark field scanning transmission electron microscopy for nano-particle atom-counting.

    PubMed

    De Backer, A; Martinez, G T; MacArthur, K E; Jones, L; Béché, A; Nellist, P D; Van Aert, S

    2015-04-01

    Quantitative annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique to characterise nano-particles on an atomic scale. Because of their limited size and beam sensitivity, the atomic structure of such particles may become extremely challenging to determine. Therefore keeping the incoming electron dose to a minimum is important. However, this may reduce the reliability of quantitative ADF STEM which will here be demonstrated for nano-particle atom-counting. Based on experimental ADF STEM images of a real industrial catalyst, we discuss the limits for counting the number of atoms in a projected atomic column with single atom sensitivity. We diagnose these limits by combining a thorough statistical method and detailed image simulations.

  14. Refinement of Magnetite Nanoparticles by Coating with Organic Stabilizers

    PubMed Central

    Cîrcu, Monica; Nan, Alexandrina; Borodi, Gheorghe; Liebscher, Jürgen; Turcu, Rodica

    2016-01-01

    Magnetite nanoparticles are of great importance in nanotechnology and nanomedicine and have found manifold applications. Here, the effect of coating of magnetite nanoparticles with organic stabilizers, such as O-phosphoryl ethanolamine, glycerol phosphate, phospho-l-ascorbic acid, phospho-d,l-serine, glycolic acid, lactic acid, d,l-malic acid, and d,l-mandelic acid was studied. Remarkably, this procedure led to an improvement of saturation magnetization in three cases rather than to an unfavorable decrease as usually observed. Detailed X-ray powder diffraction investigations revealed that changes in the average crystallite occurred in the coating process. Surprisingly, changes of the average crystallite sizes in either direction were further observed, when the exposure time to the stabilizer was increased. These results imply a new mechanism for the well-known coating of magnetite nanoparticles with stabilizers. Instead of the hitherto accepted simple anchoring of the stabilizers to the magnetite nanoparticle surfaces, a more complex recrystallization mechanism is likely, wherein partial re-dispersion of magnetite moieties from the nanoparticles and re-deposition are involved. The results can help producers and users of magnetite nanoparticles to obtain optimal results in the production of core shell magnetite nanoparticles. PMID:28335356

  15. Synthesis of Ferrite Nickel Nano-particles and Its Role as a p-Dopant in the Improvement of Hole Injection of an Organic Light-Emitting Diode

    NASA Astrophysics Data System (ADS)

    Noori, Maryam; Jafari, Mohammad Reza; Hosseini, Sayed Mohsen; Shahedi, Zahra

    2017-02-01

    We fabricated an organometallic complex based on zinc ions using zinc complex as a fluorescent in organic light-emitting diodes (OLEDs). Also, the nano-particles of ferrite nickel were produced in a simple aqueous system prepared by mixing Ni (NO3)2, Fe (NO3)3 and deionized water solutions. The synthesized zinc bis (8-hydroxyquinoline) (Znq2) complex and NiFe2O4 nano-particles were characterized by using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FT-IR) as well as photoluminescence spectroscopy analysis. Their energy level was also determined by some cyclic voltammetry (CV) measurements. The maximum green photoluminescence was observed at 565 nm. The nano-particles of ferrite nickel were utilized in preparation of OLEDs by blending of the magnetic nano-particles with PEDOT:PSS and Zn-complex solutions. The electrical and optical performance of prepared OLEDs with/without doped nano-particle was studied. The samples were configured into two structures: (1) Indium Tin Oxide (ITO)/ poly(3,4-ethylenedi-oxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Znq2/(2-4-biphenylyl)-5-phenyl-oxadiazole (PBD)/aluminum (Al) and (2) ITO/PEDOT:PSS:NiFe2O4(NPs)/Znq2/PBD/Al. Obtained results showed that the current density and electroluminescence efficiency were increased and the turn-on voltage decreased (about 3 V) by using nano-particles into a PEDOT:PSS layer (Hole transport layer). Also, the electroluminescence efficiency was decreased by incorporating magnetic nano-particles into a Zn-complex layer (emissive layer). It was found that utilizing NiFe2O4 nano-particles caused an increase of hole-injection layer conductivity effectively and a decrease of the turn-on voltage.

  16. Crystallography of magnetite plaquettes and their significance as asymmetric catalysts for the synthesis of chiral organics in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Chan, Q. H. S.; Zolensky, M. E.

    2015-10-01

    We have previously observed the magnetite plaquettes in carbonaceous chondrites using scanning electron microscope (SEM) imaging, examined the crystal orientation of the polished surfaces of magnetite plaquettes in CI Orgueil using electron backscattered diffraction (EBSD) analysis, and concluded that these magnetite plaquettes are likely naturally asymmetric materials [1]. In this study, we expanded our EBSD observation to other magnetite plaquettes in Orgueil, and further examined the internal structure of these remarkable crystals with the use of X-ray computed microtomography.

  17. Crystallography of Magnetite Plaquettes and their Significance as Asymmetric Catalysts for the Synthesis of Chiral Organics in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.

    2015-01-01

    We have previously observed the magnetite plaquettes in carbonaceous chondrites using scanning electron microscope (SEM) imaging, examined the crystal orientation of the polished surfaces of magnetite plaquettes in CI Orgueil using electron backscattered diffraction (EBSD) analysis, and concluded that these magnetite plaquettes are likely naturally asymmetric materials. In this study, we expanded our EBSD observation to other magnetite plaquettes in Orgueil, and further examined the internal structure of these remarkable crystals with the use of X-ray computed microtomography.

  18. Nondestructive optical testing of 3D disperse systems with micro- and nano-particles

    NASA Astrophysics Data System (ADS)

    Bezrukova, Alexandra G.

    2005-04-01

    Nondestructive testing and analysis of three-dimensional (3D) disperse systems (DS) with micro- and nano-particles of different nature by complex of optical compatible methods can provide further progress in on-line control of water and air. The simultaneous analysis of 3D-DS by refractometry, absorbency, fluorescence and by different types of light scattering can help to elaborate the sensing elements for specific impurity control. In our research we have investigated by complex of optical methods different 3D-DS such as: proteins, nucleoproteids, lipoproteids, liposomes, viruses, virosomes, lipid emulsions, blood substitutes, latexes, liquid crystals, biological cells with various form and size (including bacterial cells), metallic powders, clays, kimberlites, zeolites, oils, crude oils, etc., and mixtures -- proteins with nucleic acids, liposomes and viruses, liquid crystals with surfactants, mixtures of clay with bacterial cells, samples of natural and water-supply waters, etc. This experience suggests that the set of optical parameters of so called second class is unique for each 3D-DS. In another words each DS can be characterized by n-dimensional vector in n-dimensional space of optical parameters. Mixtures can be considered as polycomponent and polymodal 3D-DS (such as natural water and air). Due to the fusion of various optical data it is possible to indicate by information statistical theory the inverse physical problem on the presence of impurities in mixtures (viruses, bacteria, oil, metallic particles, etc.), and in this case polymodality of particle size distribution is not an obstacle. Bank of optical data for 3D-DS is the base for analysis by information-statistical method.

  19. A CFD study of the deep bed filtration mechanism for submicron/nano-particle suspension.

    PubMed

    Tung, K L; Chang, Y L; Lai, J Y; Chang, C H; Chuang, C J

    2004-01-01

    The mechanism of the deep bed filtration for submicron and nano particles suspension was conducted by means of a force analysis on the suspended particles flow path through order-packed granular filter beds. The flow fields through the filter beds were calculated by using the commercial available CFD software--Fluent. Various types of granular packing structures, such as the simple cubic packing, body-centered packing and face-centered packing structures were chosen for analysis. The motion of suspended particle of 2.967, 0.816, 0.460 and 0.050 microm in diameter, respectively, were tracked by considering the following forces including a net gravitational force, hydraulic drag force, lift force, Brownian force, van der Waals force and a double layer force. The effects of the granular bed packing structure, the porosity of these beds and the suspended particle diameter on the capture efficiency of a granular filter bed were examined. The force analysis depicts that the inertial effect and van der Waals force increased the capture probability of particles on the granular filter bed while the lift force and the Brownian force decreased the particle deposition. Simulated results show that among the chosen packing structures, the face-center packed granular bed gives the greatest pressure drop and capture efficiency of particles due to the lower packing porosity. The simple cubic packed filter bed showed the lowest pressure drop and capture efficiency of particles due to the greatest packing porosity among the chosen packing structures. It is mainly due to the simple cubic packing structure in which there exists the free vertical downward flowing path and thus exhibits a higher packing porosity. The comparisons of the simulated capture efficiency with experimental results depicted that the body-centre packed granular bed showed the best approximation of capture efficiency compared to that of the randomly packed granular bed.

  20. Hot Extruded Polycrystalline Mg2Si with Embedded XS2 Nano-particles (X: Mo, W)

    NASA Astrophysics Data System (ADS)

    Bercegol, A.; Christophe, V.; Keshavarz, M. K.; Vasilevskiy, D.; Turenne, S.; Masut, R. A.

    2016-08-01

    Due to their abundant, inexpensive and non-toxic constituent elements, magnesium silicide and related alloys are attractive for large-scale thermoelectric (TE) applications in the 500-800 K temperature range, in particular for energy conversion. In this work, we propose a hot extrusion method favorable for large-scale production, where the starting materials (Mg2Si and XS2, X: W, Mo) are milled together in a sealed vial. The MoS2 nano-particles (0.5-2 at.%) act as solid lubricant during the extrusion process, thus facilitating material densification, as confirmed by density measurements based on Archimedes' method. Scanning electron microscopy images of bulk extruded specimens show a wide distribution of grain size, covering the range from 0.1 μm to 10 μm, and energy dispersive spectroscopy shows oxygen preferentially distributed at the grain boundaries. X-ray diffraction analysis shows that the major phase is the expected cubic structure of Mg2Si. The TE properties of these extruded alloys have been measured by the Harman method between 300 K and 700 K. Resistivity values at 700 K vary between 370 μΩ m and 530 μΩ m. The ZT value reaches a maximum of 0.26 for a sample with 2 at.% MoS2. Heat conductivity is reduced for extruded samples containing MoS2, which most likely behave as scattering centers for phonons. The reason why the WS2 particles do not bring any enhancement, for either densification or heat transfer reduction, might be linked to their tendency to agglomerate. These results open the way for further investigation to optimize the processing parameters for this family of TE alloys.

  1. Protection of cisplatin-induced spermatotoxicity, DNA damage and chromatin abnormality by selenium nano-particles.

    PubMed

    Rezvanfar, Mohammad Amin; Rezvanfar, Mohammad Ali; Shahverdi, Ahmad Reza; Ahmadi, Abbas; Baeeri, Maryam; Mohammadirad, Azadeh; Abdollahi, Mohammad

    2013-02-01

    Cisplatin (CIS), an anticancer alkylating agent, induces DNA adducts and effectively cross links the DNA strands and so affects spermatozoa as a male reproductive toxicant. The present study investigated the cellular/biochemical mechanisms underlying possible protective effect of selenium nano-particles (Nano-Se) as an established strong antioxidant with more bioavailability and less toxicity, on reproductive toxicity of CIS by assessment of sperm characteristics, sperm DNA integrity, chromatin quality and spermatogenic disorders. To determine the role of oxidative stress (OS) in the pathogenesis of CIS gonadotoxicity, the level of lipid peroxidation (LPO), antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) and peroxynitrite (ONOO) as a marker of nitrosative stress (NS) and testosterone (T) concentration as a biomarker of testicular function were measured in the blood and testes. Thirty-two male Wistar rats were equally divided into four groups. A single IP dose of CIS (7 mg/kg) and protective dose of Nano-Se (2 mg/kg/day) were administered alone or in combination. The CIS-exposed rats showed a significant increase in testicular and serum LPO and ONOO level, along with a significant decrease in enzymatic antioxidants levels, diminished serum T concentration and abnormal histologic findings with impaired sperm quality associated with increased DNA damage and decreased chromatin quality. Coadministration of Nano-Se significantly improved the serum T, sperm quality, and spermatogenesis and reduced CIS-induced free radical toxic stress and spermatic DNA damage. In conclusion, the current study demonstrated that Nano-Se may be useful to prevent CIS-induced gonadotoxicity through its antioxidant potential.

  2. Synthesis, structural, dielectric and magnetic properties of polyol assisted copper ferrite nano particles

    NASA Astrophysics Data System (ADS)

    Pavithradevi, S.; Suriyanarayanan, N.; Boobalan, T.

    2017-03-01

    Nanocrystalline copper ferrite CuFe2O4 is synthesized by co-precipitation method in ethylene glycol as chelating agent, using sodium Hydroxide as precipitator at pH 8. The as synthesized CuFe2O4 is annealed at temperatures of 350 °C, 700 °C, and 1050 °C for 2 h respectively. The thermal analysis of the synthesized sample is done by TG technique. It is shown that at 260 °C ethylene glycol has evaporated completely and after 715 °C, spinel ferrite is formed with a cubic structure. The calculated lattice parameters are in agreement with the reported values. FTIR spectra of CuFe2O4 nano particles are as synthesized and annealed at 1050 °C and recorded between 400 cm-1 and 4000 cm-1. It shows that when the temperature increases ethylene glycol gradually evaporates. Finally, nano crystalline single phase spinel ferrite is obtained. X-ray diffraction (XRD) and electron diffraction (EDS) studies show that the sample is indexed as the face centered cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the particles are flaky and spherical with the crystallite size in the range of 25-34 nm. From the dielectric studies, the dielectric constant decreases as the frequency increases. Low value of dielectric loss at higher frequencies suggests that the material is suitable for high frequency applications. AC conductivity increases with frequency. The magnetic properties of the samples are measured using a vibrating sample magnetometer (VSM) at room temperature, which shows that the sample exhibited a typical super paramagnetic behavior at low temperature. The saturation magnetization, remanant magnetism, and coercivity increases with applied field.

  3. Protection of cisplatin-induced spermatotoxicity, DNA damage and chromatin abnormality by selenium nano-particles

    SciTech Connect

    Rezvanfar, Mohammad Amin; Rezvanfar, Mohammad Ali; Shahverdi, Ahmad Reza; Ahmadi, Abbas; Baeeri, Maryam; Mohammadirad, Azadeh; Abdollahi, Mohammad

    2013-02-01

    Cisplatin (CIS), an anticancer alkylating agent, induces DNA adducts and effectively cross links the DNA strands and so affects spermatozoa as a male reproductive toxicant. The present study investigated the cellular/biochemical mechanisms underlying possible protective effect of selenium nano-particles (Nano-Se) as an established strong antioxidant with more bioavailability and less toxicity, on reproductive toxicity of CIS by assessment of sperm characteristics, sperm DNA integrity, chromatin quality and spermatogenic disorders. To determine the role of oxidative stress (OS) in the pathogenesis of CIS gonadotoxicity, the level of lipid peroxidation (LPO), antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) and peroxynitrite (ONOO) as a marker of nitrosative stress (NS) and testosterone (T) concentration as a biomarker of testicular function were measured in the blood and testes. Thirty-two male Wistar rats were equally divided into four groups. A single IP dose of CIS (7 mg/kg) and protective dose of Nano-Se (2 mg/kg/day) were administered alone or in combination. The CIS-exposed rats showed a significant increase in testicular and serum LPO and ONOO level, along with a significant decrease in enzymatic antioxidants levels, diminished serum T concentration and abnormal histologic findings with impaired sperm quality associated with increased DNA damage and decreased chromatin quality. Coadministration of Nano-Se significantly improved the serum T, sperm quality, and spermatogenesis and reduced CIS-induced free radical toxic stress and spermatic DNA damage. In conclusion, the current study demonstrated that Nano-Se may be useful to prevent CIS-induced gonadotoxicity through its antioxidant potential. Highlights: ► Cisplatin (CIS) affects spermatozoa as a male reproductive toxicant. ► Effect of Nano-Se on CIS-induced spermatotoxicity was investigated. ► CIS-exposure induces oxidative sperm DNA damage

  4. Modeling Magnetite Reflectance Spectra Using Hapke Theory and Existing Optical Constants

    NASA Technical Reports Server (NTRS)

    Roush, T. L.; Blewett, D. T.; Cahill, J. T. S.

    2016-01-01

    Magnetite is an accessory mineral found in terrestrial environments, some meteorites, and the lunar surface. The reflectance of magnetite powers is relatively low [1], and this property makes it an analog for other dark Fe- or Ti-bearing components, particularly ilmenite on the lunar surface. The real and imaginary indices of refraction (optical constants) for magnetite are available in the literature [2-3], and online [4]. Here we use these values to calculate the reflectance of particulates and compare these model spectra to reflectance measurements of magnetite available on-line [5].

  5. [Interaction of fibrinogen with magnetite nanoparticles].

    PubMed

    Bychkova, A V; Sorokina, O N; Kovarskiĭ, A L; Shapiro, A B; Leonova, V B; Rozenfel'd, M A

    2010-01-01

    The interaction between fibrinogen and magnetite nanoparticles in solution has been studied by the methods of spin labeling, ferromagnetic resonance, dynamic and Rayleigh light scattering. It was shown that protein molecules adsorb on the surface of nanoparticles to form multilayer protein covers. The number of molecules adsorbed on one nanoparticle amounts to approximately 65 and the thickness of the adsorption layer amounts to approximately 27 nm. Separate nanoparticles with fibrinogen covers (clusters) form aggregates due to interactions of the end D-domains of fibrinogen. Under the influence of direct magnetic field, nanoparticles with adsorbed proteins form linear aggregates parallel to force lines. It was shown that the rate of protein coagulation during the formation of fibrin gel under the action of thrombin on fibrinogen decreases approximately 2 times in the presence of magnetite nanoparticles, and the magnitude of the average fiber mass-length ratio grows.

  6. Preparation and photoluminescence properties of MMoO4 (M = Cu, Ni, Zn) nano-particles synthesized via electrolysis

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Yin, Jiajia; Min, Fanqi; Jia, Lili; Zhang, Daoming; Zhang, Quansheng; Xie, Jingying

    2017-01-01

    Metal molybdate (MMoO4, M = Cu, Ni, Zn) nano-particles were successfully synthesized by electrochemical method in a cation exchange membrane electrolytic cell with Na2MoO4 solution as anolyte, diluted hydrochloric acid (HCl) as catholyte, metal (Cu, Ni, Zn) as anode and stainless steel as cathode. The composition, morphology, structure, microstructure and photoluminescence property of the synthesized MMoO4 were investigated and characterized. The results show that the photoluminescence spectra of electrolytic synthesized MMoO4 have fine structures, which is markedly different from the existing research.

  7. Electrochemistry and dissolution kinetics of magnetite and ilmenite

    USGS Publications Warehouse

    White, A.F.; Peterson, M.L.; Hochella, M.F.

    1994-01-01

    Natural samples of magnetite and ilmenite were experimentally weathered in pH 1-7 anoxic solutions at temperatures of 2-65 ??C. Reaction of magnetite is described as [Fe2+Fe23+]O4(magnetite) + 2H+ ??? ??[Fe23+]O3(maghemite) + Fe2+ + H2O. Dynamic polarization experiments using magnetite electrodes confirmed that this reaction is controlled by two electrochemical half cells, 3[Fe2+Fe23+]O4(magnetite) ??? 4??[Fe23+]O3(maghemite) + Fe2+ + 2e- and [Fe2+Fe23+]O4(magnetite) + 8 H+ + 2e- ??? 3Fe2+ + 4H2O, which result in solid state Fe3+ reduction, formation of an oxidized layer and release of Fe(II) to solution. XPS data revealed that iron is present in the ferric state in the surfaces of reacted magnetite and ilmenite and that the Ti Fe ratio increased with reaction pH for ilmenite. Short-term (<36 h) release rates of Fe(II) were linear with time. Between pH 1 and 7, rates varied between 0.3 and 13 ?? 10-14 mol ?? cm-2 ?? s-1 for magnetite and 0.05 and 12.3 ?? 10-14 mol ?? cm-2 ?? s-1 for ilmenite. These rates are two orders of magnitude slower than electrochemical rates determined by Tafel and polarization resistance measurements. Discrepancies are due to both differences in geometric and BET surface area estimates and in the oxidation state of the mineral surface. In long-term closed-system experiments (<120 days), Fe(II) release slowed with time due to the passivation of the surfaces by increasing thicknesses of oxide surface layers. A shrinking core model, coupling surface reaction and diffusion transport, predicted that at neutral pH, the mean residence time for sand-size grains of magnetite and ilmenite will exceed 107 years. This agrees with long-term stability of these oxides in the geologic record. ?? 1994.

  8. Using a biomimetic membrane surface experiment to investigate the activity of the magnetite biomineralisation protein Mms6† †Electronic supplementary information (ESI) available: Including Mms6 protein and peptide sequences, additional QCM-D and SEM data and protein modelling. See DOI: 10.1039/c5ra16469a Click here for additional data file.

    PubMed Central

    Bird, Scott M.; Rawlings, Andrea E.; Galloway, Johanna M.

    2016-01-01

    Magnetotactic bacteria are able to synthesise precise nanoparticles of the iron oxide magnetite within their cells. These particles are formed in dedicated organelles termed magnetosomes. These lipid membrane compartments use a range of biomineralisation proteins to nucleate and regulate the magnetite crystallisation process. A key component is the membrane protein Mms6, which binds to iron ions and helps to control the formation of the inorganic core. We have previously used Mms6 on gold surfaces patterned with a self-assembled monolayer to successfully produce arrays of magnetic nanoparticles. Here we use this surface system as a mimic of the interior face of the magnetosome membrane to study differences between intact Mms6 and the acid-rich C-terminal peptide subregion of the Mms6 protein. When immobilised on surfaces, the peptide is unable to reproduce the particle size or homogeneity control exhibited by the full Mms6 protein in our experimental setup. Moreover, the peptide is unable to support anchoring of a dense array of nanoparticles to the surface. This system also allows us to deconvolute particle binding from particle nucleation, and shows that Mms6 particle binding is less efficient when supplied with preformed magnetite nanoparticles when compared to particles precipitated from solution in the presence of the surface immobilised Mms6. This suggests that Mms6 binds to iron ions rather than to magnetite surfaces in our system, and is perhaps a nucleating agent rather than a controller of magnetite crystal growth. The comparison between the peptide and the protein under identical experimental conditions indicates that the full length sequence is required to support the full function of Mms6 on surfaces. PMID:27019707

  9. Tuning of platinum nano-particles by Au usage in their binary alloy for direct ethanol fuel cell: Controlled synthesis, electrode kinetics and mechanistic interpretation

    NASA Astrophysics Data System (ADS)

    Dutta, Abhijit; Mondal, Achintya; Datta, Jayati

    2015-06-01

    Understanding of the electrode-kinetics and mechanism of ethanol oxidation reaction (EOR) is of considerable interest for optimizing electro-catalysis in direct ethanol fuel cell (DEFC). This work attempts to design Pt based electro-catalyst on carbon support, tuned with gold nano-particles (NPs), for their use in DEFC operating in alkaline medium. The platinum-gold alloyed NPs are synthesized at desired compositions and size (2-10 nm) by controlled borohydride reduction method and successfully characterized by XRD, TEM, EDS and XPS techniques. The kinetic parameters along with the activation energies for the EOR are evaluated over the temperature range 20-80 °C and the oxidation reaction products estimated through ion chromatographic analysis. Compared to single Pt/C catalyst, the over potential of EOR is reduced by ca. 500 mV, at the onset during the reaction, for PtAu/C alloy with only 23% Pt content demonstrating the ability of Au and/or its surface oxides providing oxygen species at much lower potentials compared to Pt. Furthermore, a considerable increase in the peak power density (>191%) is observed in an in-house fabricated direct ethanol anion exchange membrane fuel cell, DE(AEM)FC using the best performing Au covered Pt electrode (23% Pt) compared to the monometallic Pt catalyst.

  10. Core-Shell Soy Protein-Soy Polysaccharide Complex (Nano)particles as Carriers for Improved Stability and Sustained Release of Curcumin.

    PubMed

    Chen, Fei-Ping; Ou, Shi-Yi; Tang, Chuan-He

    2016-06-22

    Using soy protein isolate (SPI) and soy-soluble polysaccharides (SSPS) as polymer matrixes, this study reported a novel process to fabricate unique core-shell complex (nano)particles to perform as carriers for curcumin (a typical poorly soluble bioactive). In the process, curcumin-SPI nanocomplexes were first formed at pH 7.0 and then coated by SSPS. At this pH, the core-shell complex was formed in a way the SPI nanoparticles might be incorporated into the interior of SSPS molecules without distinctly affecting the size and morphology of particles. The core-shell structure was distinctly changed by adjusting pH from 7.0 to 4.0. At pH 4.0, SSPS was strongly bound to the surface of highly aggregated SPI nanoparticles, and as a consequence, much larger complexes were formed. The bioaccessibility of curcumin in the SPI-curcumin complexes was unaffected by the SSPS coating. However, the core-shell complex formation greatly improved the thermal stability and controlled release properties of encapsulated curcumin. The improvement was much better at pH 4.0 than that at pH 7.0. All of the freeze-dried core-shell complex preparations exhibited good redispersion behavior. The findings provide a simple approach to fabricate food-grade delivery systems for improved water dispersion, heat stability, and even controlled release of poorly soluble bioactives.

  11. High fluorescence emission silver nano particles coated with poly (styrene-g-soybean oil) graft copolymers: Antibacterial activity and polymerization kinetics.

    PubMed

    Hazer, Baki; Kalaycı, Özlem A

    2017-05-01

    Autoxidation of poly unsaturated fatty acids makes negative effect on foods. In this work, this negative effect was turned to a great advantage using autoxidized soybean oil as a macroperoxide nanocomposite initiator containing silver nano particles in free radical polymerization of vinyl monomers. The synthesis of soybean oil macro peroxide was carried out by exposing soybean oil to air oxygen with the presence of silver nanoparticles (Ag NPs) at room temperature. Autoxidized soybean oil macroperoxide containing silver nanoparticles (Agsbox) successfully initiated the free radical polymerization of styrene in order to obtain Polystyrene (PS)-g-soybean oil graft copolymer containing Ag NPs. Both autoxidized soybean oil and PS-g-sbox with Ag NPs showed a surface plasmon resonance and high fluorescence emission. Overall rate constant (K) of styrene polymerization initiated by autoxidized soybean oil macroperoxide with Ag NPs was found to be K=1.95.10(-4)Lmol(-1)s(-1) at 95°C. Antibacterial efficiency was observed in the PS-g-soybean oil graft copolymer film samples containing Ag NPs. (1)H NMR and GPC techniques were used for the structural analysis of the fractionated polymeric oils.

  12. Study of structure and magnetic properties of Ni-Zn ferrite nano-particles synthesized via co-precipitation and reverse micro-emulsion technique

    NASA Astrophysics Data System (ADS)

    Abdullah Dar, M.; Shah, Jyoti; Siddiqui, W. A.; Kotnala, R. K.

    2014-08-01

    Nano-crystalline Ni-Zn ferrites were synthesized by chemical co-precipitation and reverse micro-emulsion technique with an average crystallite size of 11 and 6 nm, respectively. The reverse micro-emulsion method has been found to be more appropriate for nano-ferrite synthesis as the produced particles are monodisperse and highly crystalline. Zero-field cooled and field cooled magnetization study under different magnetic fields and magnetic hysteresis loops at different temperatures have been performed. The non-saturated M-H loops, absence of hysteresis, and coercivity at room temperature are indicative of the presence of super paramagnetic and single-domain nano-particles for both the materials. In sample `a', the blocking temperature ( T B) has been observed to decrease from 255 to 120 K on increasing the magnetic field from 50 to 1,000 Oe, which can be attributed to the reduction of magneto crystalline anisotropy constant. The M S and coercivity were found to be higher for sample `a' as compared with sample `b' since surface effects are neglected on increasing the crystallite size.

  13. Fourier transform infrared and Raman spectroscopy studies on magnetite/Ag/antibiotic nanocomposites

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Olena; Jurga-Stopa, Justyna; Coy, Emerson; Peplinska, Barbara; Pietralik, Zuzanna; Jurga, Stefan

    2016-02-01

    This article presents a study on the detection of antibiotics in magnetite/Ag/antibiotic nanocomposites using Fourier transform infrared (FTIR) and Raman spectroscopy. Antibiotics with different spectra of antimicrobial activities, including rifampicin, doxycycline, cefotaxime, and ceftriaxone, were studied. Mechanical mixtures of antibiotics and magnetite/Ag nanocomposites, as well as antibiotics and magnetite nanopowder, were investigated in order to identify the origin of FTIR bands. FTIR spectroscopy was found to be an appropriate technique for this task. The spectra of the magnetite/Ag/antibiotic nanocomposites exhibited very weak (for doxycycline, cefotaxime, and ceftriaxone) or even no (for rifampicin) antibiotic bands. This FTIR "invisibility" of antibiotics is ascribed to their adsorbed state. FTIR and Raman measurements show altered Csbnd O, Cdbnd O, and Csbnd S bonds, indicating adsorption of the antibiotic molecules on the magnetite/Ag nanocomposite structure. In addition, a potential mechanism through which antibiotic molecules interact with magnetite/Ag nanoparticle surfaces is proposed.

  14. The effect of acid–base clustering and ions on the growth of atmospheric nano-particles

    PubMed Central

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J.; Dunne, Eimear M.; Flagan, Richard C.; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J.; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K.; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P.; Ruuskanen, Taina; Santos, Filipe D.; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N.; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E.; Wagner, Paul E.; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M.; Virtanen, Annele; Donahue, Neil M.; Carslaw, Kenneth S.; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R.; Kulmala, Markku

    2016-01-01

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere. PMID:27197574

  15. The effect of acid–base clustering and ions on the growth of atmospheric nano-particles

    DOE PAGES

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; ...

    2016-05-20

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted formore » in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. Furthermore, we bring these observations into a coherent framework and discuss their significance in the atmosphere.« less

  16. Study on the Particle Size Distribution Nano-Particles of Mining Minerals on Whiteness of Triaxial Body

    NASA Astrophysics Data System (ADS)

    Mathur, Ravi; Soni, Aditi

    White wares produced worldwide represent the foundation of much of the ceramic industry; Porcelain bodies fabricated from triaxial mixtures of clay, quartz and feldspar with different size and amounts of nano particles were investigated. Although the purity of raw materials has a strong effect on the colour of the fired bodies, the particle size of raw materials also effect the whiteness The raw material mining minerals china Clay, Feldspar, quarts were prepared of various sized nano particles contains 10.60 -20.22%, 56.84- 70.80 % and 34.87-50.76 % of 100nm respectively. The fired bodies of raw mining minerals and triaxial bodies were subjected to colour measurement. The differences in whiteness were compared and discussed. The studies so far carried out is upto 400 mesh size while the present study has included up to 100nm particle size. A statistical correlation between whiteness of feldspar and triaxial body was also carried out. The correlation between china clay and triaxial body are 0.53, 0.57 and 0.66 for china clay similarly correlation for feldspar is 0.49, 0.73 and 0.83 for triaxial body it are 0.97, 0.84 and 0.75 for A1, A2 and A3 samples. Correlation between china clay and feldspar with triaxial body are 0.79 and 0.92 respectively.

  17. Optical and thermoelectric properties of nano-particles based Bi2(Te1-xSex)3 thin films

    NASA Astrophysics Data System (ADS)

    Adam, A. M.; Lilov, E.; Petkov, P.

    2017-01-01

    Nano-particles of Bi2Te3 and Bi2(Te1-xSex)3 films were deposited using vacuum thermal evaporation technique from previously prepared bulk alloys synthesized by melting method. Optical and thermoelectric properties were studied in the temperature range of 300-473K. The formation of none- and Se-doped Bi2Te3 nano-particles was verified by EDX and XRD analysis. TEM, SEM and AFM analysis showed the prepared films are polycrystalline in nature. The measurements of electrical conductivity and Seebeck coefficient, alongside with thermal conductivity calculations, resulted in the highest values of thermoelectric power at high temperature to be reported. The maximum value of power factor was calculated at 62.82917 μWK-2cm-1 for (Bi2Se0.3Te1.7) sample at 463 K. On the addition of Se to Bi2Te3 film, a significant decrease of the electronic thermal conductivity (Kel) from 2.181 × 10-2 to 0.598 × 10-2 (μW/cm.K) could be achieved. Figure of merit (ZT) calculations showed a maximum value of 0.85 at room temperature, for Bi2Te3. Besides the increase of ZT value for all samples at higher temperature, surprisingly, a value of 2.75 for (Bi2Se1.2Te1.8) was obtained. We believe our results could open avenues for new applications.

  18. The effect of acid-base clustering and ions on the growth of atmospheric nano-particles.

    PubMed

    Lehtipalo, Katrianne; Rondo, Linda; Kontkanen, Jenni; Schobesberger, Siegfried; Jokinen, Tuija; Sarnela, Nina; Kürten, Andreas; Ehrhart, Sebastian; Franchin, Alessandro; Nieminen, Tuomo; Riccobono, Francesco; Sipilä, Mikko; Yli-Juuti, Taina; Duplissy, Jonathan; Adamov, Alexey; Ahlm, Lars; Almeida, João; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Downard, Andrew J; Dunne, Eimear M; Flagan, Richard C; Guida, Roberto; Hakala, Jani; Hansel, Armin; Jud, Werner; Kangasluoma, Juha; Kerminen, Veli-Matti; Keskinen, Helmi; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Kupiainen-Määttä, Oona; Laaksonen, Ari; Lawler, Michael J; Leiminger, Markus; Mathot, Serge; Olenius, Tinja; Ortega, Ismael K; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud; Rissanen, Matti P; Ruuskanen, Taina; Santos, Filipe D; Schallhart, Simon; Schnitzhofer, Ralf; Simon, Mario; Smith, James N; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Tomé, António; Vaattovaara, Petri; Vehkamäki, Hanna; Vrtala, Aron E; Wagner, Paul E; Williamson, Christina; Wimmer, Daniela; Winkler, Paul M; Virtanen, Annele; Donahue, Neil M; Carslaw, Kenneth S; Baltensperger, Urs; Riipinen, Ilona; Curtius, Joachim; Worsnop, Douglas R; Kulmala, Markku

    2016-05-20

    The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.

  19. Kinetic modeling of the formation and growth of inorganic nano-particles during pulverized coal char combustion in O2/N2 and O2/CO2 atmospheres

    DOE PAGES

    Shaddix, Christopher R.; Niu, Yanqing; Hui, Shi'en; ...

    2016-08-01

    In this formation of nano-particles during coal char combustion, the vaporization of inorganic components in char and the subsequent homogeneous particle nucleation, heterogeneous condensation, coagulation, and coalescence play decisive roles. Furthermore, conventional measurements cannot provide detailed information on the dynamics of nano-particle formation and evolution, In this study, a sophisticated intrinsic char kinetics model that considers ash effects (including ash film formation, ash dilution, and ash vaporization acting in tandem), both oxidation and gasification by CO2 and H2O, homogeneous particle nucleation, heterogeneous vapor condensation, coagulation, and and coalescence mechanisms is developed and used to compare the temporal evolution of themore » number and size of nano-particles during coal char particle combustion as a function of char particle size, ash content, and oxygen content in O2/N2 and O2/CO2 atmospheres .« less

  20. Microwave anneal effect on magnetic properties of Ni 0.6Zn 0.4Fe 2O 4 nano-particles prepared by conventional hydrothermal method

    NASA Astrophysics Data System (ADS)

    Wang, Zhongzhu; Xie, Yanyu; Wang, Peihong; Ma, Yongqing; Jin, Shaowei; Liu, Xiansong

    2011-12-01

    Ni0.6Zn0.4Fe2O4 ferrite nano-particles with a crystallite size of about 20 nm were prepared by the conventional hydrothermal method, followed by annealing in a microwave oven for 7.5-15 min. The microstructure and magnetic properties of the samples were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The microwave annealing process has slight effect on the morphology and size of Ni0.6Zn0.4Fe2O4 ferrite nano-particles. However it reduces the lattice parameter and enhances the densification of the particles, and then greatly increases the saturation magnetization (50-56 emu/g) and coercive force of the samples as compared to the non-annealing condition. The microwave annealing process is an effective way to rapidly synthesize high performance ferrite nano-particle.

  1. Adaptive neuro-fuzzy inference system (ANFIS) to predict CI engine parameters fueled with nano-particles additive to diesel fuel

    NASA Astrophysics Data System (ADS)

    Ghanbari, M.; Najafi, G.; Ghobadian, B.; Mamat, R.; Noor, M. M.; Moosavian, A.

    2015-12-01

    This paper studies the use of adaptive neuro-fuzzy inference system (ANFIS) to predict the performance parameters and exhaust emissions of a diesel engine operating on nanodiesel blended fuels. In order to predict the engine parameters, the whole experimental data were randomly divided into training and testing data. For ANFIS modelling, Gaussian curve membership function (gaussmf) and 200 training epochs (iteration) were found to be optimum choices for training process. The results demonstrate that ANFIS is capable of predicting the diesel engine performance and emissions. In the experimental step, Carbon nano tubes (CNT) (40, 80 and 120 ppm) and nano silver particles (40, 80 and 120 ppm) with nanostructure were prepared and added as additive to the diesel fuel. Six cylinders, four-stroke diesel engine was fuelled with these new blended fuels and operated at different engine speeds. Experimental test results indicated the fact that adding nano particles to diesel fuel, increased diesel engine power and torque output. For nano-diesel it was found that the brake specific fuel consumption (bsfc) was decreased compared to the net diesel fuel. The results proved that with increase of nano particles concentrations (from 40 ppm to 120 ppm) in diesel fuel, CO2 emission increased. CO emission in diesel fuel with nano-particles was lower significantly compared to pure diesel fuel. UHC emission with silver nano-diesel blended fuel decreased while with fuels that contains CNT nano particles increased. The trend of NOx emission was inverse compared to the UHC emission. With adding nano particles to the blended fuels, NOx increased compared to the net diesel fuel. The tests revealed that silver & CNT nano particles can be used as additive in diesel fuel to improve combustion of the fuel and reduce the exhaust emissions significantly.

  2. Observations of magnetite dissolution in poorly drained soils

    USGS Publications Warehouse

    Grimley, D.A.; Arruda, N.K.

    2007-01-01

    Dissolution of strongly magnetic minerals is a common and relatively rapid phenomenon in poorly drained soils of the central United States, resulting in low magnetic susceptibility (MS). Low Eh reducing conditions are primarily responsible for magnetic mineral dissolution; a process likely mediated by iron-reducing bacteria in the presence of soil organic matter. Based on transects across drainage sequences from nine sites, natural magnetic minerals (>5 ??m) extracted from surface soil consist of 54% ?? 18% magnetite, 21% ?? 11% titanomagnetite, and 17% ?? 14% ilmenite. Magnetite and titanomagnetite dissolution, assessed by scanning electron microscopy on a 0-to-3 scale, inversely correlates with surface soil MS (r = 0.53), a proxy for soil drainage at studied transects. Altered magnetite typically displays etch pits 5 ??m) include 26% ?? 18% anthropogenic fly ash that also exhibits greater dissolution in low MS soils (r = 0.38), indicating detectable alteration can occur within 150 years in low Eh soils. Laboratory induced reduction of magnetite, titanomagnetite, and magnetic fly ash, with a citrate-bicarbonate- dithionite solution, resulted in dissolution textures similar to those of in situ soil particles. Although experiments indicate that reductive dissolution of magnetite can occur abiotically under extreme conditions, bacteria likely play an important role in the natural environment. ?? 2007 Lippincott Williams & Wilkins, Inc.

  3. Magnetic and ultrasonic investigations on magnetite nanofluids.

    PubMed

    Nabeel Rashin, M; Hemalatha, J

    2012-12-01

    Magnetite nanofluids of various concentrations have been prepared through co-precipitation method. The structural and magnetic properties of the magnetic nanofluids have been analyzed which respectively revealed their face centered cubic crystal structure and super paramagnetic behavior. Ultrasonic investigations have been made for the nanofluids at different temperatures and magnetic fields. Open- and close-packed water structure is considered to explain the temperature effects. The inter particle interactions of surface modified nanomagnetite particle and the cluster formation are realized through the variations in ultrasonic parameters.

  4. Natural Magnetite: an efficient catalyst for the degradation of organic contaminant

    PubMed Central

    HE, Hongping; ZHONG, Yuanhong; LIANG, Xiaoliang; TAN, Wei; ZHU, Jianxi; Yan WANG, Christina

    2015-01-01

    Iron (hydr)oxides are ubiquitous earth materials that have high adsorption capacities for toxic elements and degradation ability towards organic contaminants. Many studies have investigated the reactivity of synthetic magnetite, while little is known about natural magnetite. Here, we first report the reactivity of natural magnetites with a variety of elemental impurities for catalyzing the decomposition of H2O2 to produce hydroxyl free radicals (•OH) and the consequent degradation of p-nitrophenol (p-NP). We observed that these natural magnetites show higher catalytic performance than that of the synthetic pure magnetite. The catalytic ability of natural magnetite with high phase purity depends on the surface site density while that for the magnetites with exsolutions relies on the mineralogical nature of the exsolved phases. The pleonaste exsolution can promote the generation of •OH and the consequent degradation of p-NP; the ilmenite exsolution has little effect on the decomposition of H2O2, but can increase the adsorption of p-NP on magnetite. Our results imply that natural magnetite is an efficient catalyst for the degradation of organic contaminants in nature. PMID:25958854

  5. Natural Magnetite: an efficient catalyst for the degradation of organic contaminant

    NASA Astrophysics Data System (ADS)

    He, Hongping; Zhong, Yuanhong; Liang, Xiaoliang; Tan, Wei; Zhu, Jianxi; Yan Wang, Christina

    2015-05-01

    Iron (hydr)oxides are ubiquitous earth materials that have high adsorption capacities for toxic elements and degradation ability towards organic contaminants. Many studies have investigated the reactivity of synthetic magnetite, while little is known about natural magnetite. Here, we first report the reactivity of natural magnetites with a variety of elemental impurities for catalyzing the decomposition of H2O2 to produce hydroxyl free radicals (•OH) and the consequent degradation of p-nitrophenol (p-NP). We observed that these natural magnetites show higher catalytic performance than that of the synthetic pure magnetite. The catalytic ability of natural magnetite with high phase purity depends on the surface site density while that for the magnetites with exsolutions relies on the mineralogical nature of the exsolved phases. The pleonaste exsolution can promote the generation of •OH and the consequent degradation of p-NP; the ilmenite exsolution has little effect on the decomposition of H2O2, but can increase the adsorption of p-NP on magnetite. Our results imply that natural magnetite is an efficient catalyst for the degradation of organic contaminants in nature.

  6. Origins of Magnetite Nanocrystals in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Clemett, Simon J.; Mckay, David S.; Gibson, Everett K.; Wentworth, Susan J.

    2009-01-01

    The Martian meteorite ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks. These carbonate disks are believed to have precipitated 3.9 Ga ago at beginning of the Noachian epoch on Mars during which both the oldest extant Martian surfaces were formed, and perhaps the earliest global oceans. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these magnetites are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of mag- netite and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. For example, the magnetites might have already been present in the aqueous fluids from which the carbonates were believed to have been deposited. We have sought to resolve between these hypotheses through the detailed characterized of the compo- sitional and structural relationships of the carbonate disks and associated magnetites with the orthopyroxene matrix in which they are embedded. Extensive use of focused ion beam milling techniques has been utilized for sample preparation. We then compared our observations with those from experimental thermal decomposition studies of sideritic carbonates under a range of plausible geological heating scenarios. We conclude that the vast majority of the nanocrystal magnetites present in the car- bonate disks could not have formed by any of the currently proposed thermal decomposition scenarios. Instead, we find there is considerable evidence in support of an alternative allochthonous origin for the magnetite unrelated to any shock or thermal processing of the carbonates.

  7. Magnetic microbes: Bacterial magnetite biomineralization

    SciTech Connect

    Prozorov, Tanya

    2015-09-14

    Magnetotactic bacteria are a diverse group of prokaryotes with the ability to orient and migrate along the magnetic field lines in search for a preferred oxygen concentration in chemically stratified water columns and sediments. These microorganisms produce magnetosomes, the intracellular nanometer-sized magnetic crystals surrounded by a phospholipid bilayer membrane, typically organized in chains. Magnetosomes have nearly perfect crystal structures with narrow size distribution and species-specific morphologies, leading to well-defined magnetic properties. As a result, the magnetite biomineralization in these organisms is of fundamental interest to diverse disciplines, from biotechnology to astrobiology. As a result, this article highlights recent advances in the understanding of the bacterial magnetite biomineralization.

  8. Magnetic microbes: Bacterial magnetite biomineralization.

    PubMed

    Prozorov, Tanya

    2015-10-01

    Magnetotactic bacteria are a diverse group of prokaryotes with the ability to orient and migrate along the magnetic field lines in search for a preferred oxygen concentration in chemically stratified water columns and sediments. These microorganisms produce magnetosomes, the intracellular nanometer-sized magnetic crystals surrounded by a phospholipid bilayer membrane, typically organized in chains. Magnetosomes have nearly perfect crystal structures with narrow size distribution and species-specific morphologies, leading to well-defined magnetic properties. As a result, the magnetite biomineralization in these organisms is of fundamental interest to diverse disciplines, from biotechnology to astrobiology. This article highlights recent advances in the understanding of the bacterial magnetite biomineralization.

  9. Magnetofluidization of fine magnetite powder.

    PubMed

    Valverde, J M; Espin, M J; Quintanilla, M A S; Castellanos, A

    2009-03-01

    The behavior of a fluidized bed of fine magnetite particles as affected by a cross-flow magnetic field is investigated. A distinct feature of this naturally cohesive powder, as compared to noncohesive magnetic grains usually employed in magnetofluidized beds, is that the fluidized bed displays a range of stable fluidization even in the absence of an external magnetic field. Upon application of the magnetic field, the interval of stable fluidization is extended to higher gas velocities and bed expansion is enhanced. We have measured the tensile strength as affected by application of the external magnetic field according to two different operation modes. In the H off-on operation mode, the bed is driven to bubbling in the absence of external magnetic field. Once the gas velocity is decreased below the bubbling onset and the bed has returned to stable fluidization due to natural cohesive forces, the field is applied. In the H on-on mode, the field is maintained during the whole process of bubbling and return to stable fluidization. It is found that the tensile strength of the naturally stabilized bed is not essentially changed by application of the field ( H off-on) since the magnetic field cannot alter the bed structure once the particles are jammed in the stable fluidization state. Magnetic forces within the bulk of the jammed bed are partially canceled as a result of the anisotropic nature of the dipole-dipole interaction between the particles, which gives rise to just a small increment of the tensile strength. On the other hand, when the field is held on during bubbling and transition to stable fluidization ( H on-on mode), the tensile strength is appreciably increased. This suggests the formation of particle chains when the particles are not constrained due to the dipole-dipole attractive interaction which affects the mechanical strength of the stably fluidized bed. Experimental data are analyzed in the light of theoretical models on magnetic surface stresses.

  10. Synthesis and characterization of magnetite/PLGA/chitosan nanoparticles

    NASA Astrophysics Data System (ADS)

    Ibarra, Jaime; Melendres, Julio; Almada, Mario; Burboa, María G.; Taboada, Pablo; Juárez, Josué; Valdez, Miguel A.

    2015-09-01

    In this work, we report the synthesis and characterization of a new hybrid nanoparticles system performed by magnetite nanoparticles, loaded in a PLGA matrix, and stabilized by different concentrations of chitosan. Magnetite nanoparticles were hydrophobized with oleic acid and entrapped in a PLGA matrix by the emulsion solvent evaporation method, after that, magnetite/PLGA/chitosan nanoparticles were obtained by adding dropwise magnetite/PLGA nanoparticles in chitosan solutions. Magnetite/PLGA nanoparticles produced with different molar ratios did not show significant differences in size and the 3:1 molar ratio showed best spherical shapes as well as uniform particle size. Isothermal titration calorimetry studies demonstrated that the first stage of PLGA-chitosan interaction is mostly regulated by electrostatic forces. Based on a single set of identical sites model, we obtained for the average number of binding sites a value of 3.4, which can be considered as the number of chitosan chains per nanoparticle. This value was confirmed by using a model based on the DLVO theory and fitting zeta potential measurements of magnetite/PLGA/chitosan nanoparticles. From the adjusted parameters, we found that an average number of chitosan molecules of 3.6 per nanoparticle are attached onto the surface of the PLGA matrix. Finally, we evaluated the effect of surface charge of nanoparticles on a membrane model of endothelial cells performed by a mixture of three phospholipids at the air-water interface. Different isotherms and adsorption curves show that cationic surface of charged nanoparticles strongly interact with the phospholipids mixture and these results can be the basis of future experiments to understand the nanoparticles- cell membrane interaction.

  11. Optically sensitive devices based on Pt nano particles fabricated by atomic layer deposition and embedded in a dielectric stack

    NASA Astrophysics Data System (ADS)

    Mikhelashvili, V.; Padmanabhan, R.; Meyler, B.; Yofis, S.; Atiya, G.; Cohen-Hyams, Z.; Weindling, S.; Ankonina, G.; Salzman, J.; Kaplan, W. D.; Eisenstein, G.

    2015-10-01

    We report a series of metal insulator semiconductor devices with embedded Pt nano particles (NPs) fabricated using a low temperature atomic layer deposition process. Optically sensitive nonvolatile memory cells as well as optical sensors: (i) varactors, whose capacitance-voltage characteristics, nonlinearity, and peak capacitance are strongly dependent on illumination intensity; (ii) highly linear photo detectors whose responsivity is enhanced due to the Pt NPs. Both single devices and back to back pairs of diodes were used. The different configurations enable a variety of functionalities with many potential applications in biomedical sensing, environmental surveying, simple imagers for consumer electronics and military uses. The simplicity and planar configuration of the proposed devices makes them suitable for standard CMOS fabrication technology.

  12. Optically sensitive devices based on Pt nano particles fabricated by atomic layer deposition and embedded in a dielectric stack

    SciTech Connect

    Mikhelashvili, V.; Padmanabhan, R.; Eisenstein, G.; Meyler, B.; Yofis, S.; Weindling, S.; Salzman, J.; Atiya, G.; Cohen-Hyams, Z.; Kaplan, W. D.; Ankonina, G.

    2015-10-07

    We report a series of metal insulator semiconductor devices with embedded Pt nano particles (NPs) fabricated using a low temperature atomic layer deposition process. Optically sensitive nonvolatile memory cells as well as optical sensors: (i) varactors, whose capacitance-voltage characteristics, nonlinearity, and peak capacitance are strongly dependent on illumination intensity; (ii) highly linear photo detectors whose responsivity is enhanced due to the Pt NPs. Both single devices and back to back pairs of diodes were used. The different configurations enable a variety of functionalities with many potential applications in biomedical sensing, environmental surveying, simple imagers for consumer electronics and military uses. The simplicity and planar configuration of the proposed devices makes them suitable for standard CMOS fabrication technology.

  13. In-situ synthesis of Au nano particles of co-existing morphologies in liquid crystalline matrix

    SciTech Connect

    Dan, Kaustabh Datta, Alokmay

    2015-06-24

    The present study describes the in-situ synthesis of Au nano particles (Au-NP) in the room temperature nematic liquid crystalline (LC) substance MBBA (N-4 methoxybenzylidene 4 butylaniline) without any external reducing or stabilizing agents. UV-Visible absorption and fluorescence spectroscopy clearly show formation of Au-NP within the LC matrix through the plasmon resonance peak for the NPs and EDAX measurements confirm this formation. Transmission electron Microscopy shows co-existence of spherical and prismatic NPs. FTIR spectroscopy shows a considerable shift in the C=N stretch band pointing to the location of the growth centre of the NPs. Polarization microscopy data indicates a definite phase ordering and texture transformation from Nematic to highly ordered smectic mesophase.

  14. Structural, electrical and magnetic characteristics of nickel substituted cobalt ferrite nano particles, synthesized by self combustion method

    NASA Astrophysics Data System (ADS)

    Sontu, Uday Bhasker; Yelasani, Vijayakumar; Musugu, Venkata Ramana Reddy

    2015-01-01

    Nickel-substituted cobalt ferrite nano-particles are synthesized using a self-combustion method. Aqueous metal nitrates and citric acid form the precursors. No external oxidizing agents are used to change the pH of the precursors; this resulted in a more environment friendly synthesis. Structural, magnetic and electrical characteristics of the nano ferrites are verified using X-ray diffractometer (XRD), VSM and impedance analyzer respectively. Phase formation, particle size, lattice parameter, X-ray density, saturation magnetization, coercivity, dielectric constant and electrical activation energy as function of nickel substitution in cobalt ferrite are studied. It is shown here that the magnetic and electrical properties can be tuned by varying the nickel concentration.

  15. Using Silver Nano-Particle Ink in Electrode Fabrication of High Frequency Copolymer Ultrasonic Transducers: Modeling and Experimental Investigation

    PubMed Central

    Decharat, Adit; Wagle, Sanat; Jacobsen, Svein; Melandsø, Frank

    2015-01-01

    High frequency polymer-based ultrasonic transducers are produced with electrodes thicknesses typical for printed electrodes obtained from silver (Ag) nano-particle inks. An analytical three-port network is used to study the acoustic effects imposed by a thick electrode in a typical layered transducer configuration. Results from the network model are compared to experimental findings for the implemented transducer configuration, to obtain a better understanding of acoustical effects caused by the additional printed mass loading. The proposed investigation might be supportive of identification of suitable electrode-depositing methods. It is also believed to be useful as a feasibility study for printed Ag-based electrodes in high frequency transducers, which may reduce both the cost and production complexity of these devices. PMID:25903552

  16. Photodegradation of luminescence in organic-ligand-capped Eu{sup 3+}:LaF{sub 3} nano-particles

    SciTech Connect

    King, Gavin G. G.; Taylor, Luke R.; Longdell, Jevon J.; Clarke, David J.; Quilty, J. W.

    2014-01-28

    The luminescence from europium doped lanthanum trifluoride (Eu{sup 3+}:LaF{sub 3}) nano-crystals can be greatly enhanced by capping with β-diketonate organic ligands. Here, we report on photo-stability measurements for the case of nano-crystals capped with thenoyltrifluroacetone (TTA) and compared with those capped with an inactive ligand, oleic acid. With exposure to UV pump light, we observed significant decrease in fluorescence and change in emission spectrum of the TTA-capped nano-particles whilst the fluorescence lifetime remained approximately constant. After a dose of order 70 kJ cm{sup −2}, the luminescence level was similar to that of oleic acid capped nano-crystals. We discuss possible mechanisms.

  17. SERS and DFT study of silver nano particle induced dark isomerisation in 1H-2(Phenylazo) imidazole

    NASA Astrophysics Data System (ADS)

    Hossain, Washim; Ghosh, M.; Sinha, C.; Debnath, Dilip K.; Sarkar, Uttam K.

    2013-10-01

    Raman spectra and SERS of 1H-2(Phenylazo) imidazole (PaiH) adsorbed on silver nano particles are reported. Monomolecular layer is formed at a concentration of 5 × 10-6 M. A trans-to-cis isomerisation of PaiH is suggested by the cis-signature peak at 570 cm-1. In absorption spectra a single π-π∗ band at 358 nm is observed at higher concentrations whereas the π-π∗ and the n-π∗ bands appear at 370 nm and 456 nm, respectively, at a concentration of 5 × 10-6 M. This is in support of the hypothesis of trans-to-cis-isomerisation with lowering of concentration. DFT calculations are shown.

  18. Development of fine-celled bio-fiber composite foams using physical blowing agents and nano-particles

    NASA Astrophysics Data System (ADS)

    Guo, Gangjian

    As one of eco-friendly bio-fibers, wood-fiber has been incorporated in plastics to make wood-fiber/plastic composites (WPC) with an increased stiffness, durability and lowered cost. However, these improvements are usually accompanied by loss in the ductility and impact strength of the composites. These shortcomings can be significantly improved by incorporating a fine-cell foam structure in the composites. This thesis presents the development of the foaming technology for the manufacture of fine-cell WPC foams with environmentally benign physical blowing agents (PBAs), and focuses on the elucidation of the fundamental foaming mechanisms and the related issues involved. One critical issue comes from the volatiles evolved from the wood-fiber during high temperature processing. The volatiles, as a blowing agent, can contribute to the foaming process. However, they lead to gross deterioration of the cell structure of WPC foams. The presence of volatiles makes foaming of WPC "a poorly understood black art". With the use of PBAs, a strategy of lowering processing temperature becomes feasible, to suppress the generation of volatiles. A series of PBA-based experiments were designed using a statistical design of experiments (DOE) technique, and were performed to establish the relationship of processing and material variables with the structure of WPC foams. Fundamental foaming behaviors for two different PBAs and two different polymer systems were identified. WPC foams with a fine-cell morphology and a desired density were successfully obtained at the optimized conditions. Another limitation for the wider application of WPC is their flammability. Innovative use of a small amount of nano-clay in WPC significantly improved the flame-retarding property of WPC, and the key issue was to achieve a high degree of exfoliation of nano-particles in the polymer matrix, to achieve a desired flammability reduction. The synergistic effects of nano-particles in foaming of WPC were

  19. Optical micro resonance based sensor schemes for detection and identification of nano particles and biological agents in situ

    NASA Astrophysics Data System (ADS)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schweiger, Gustav; Ostendorf, Andreas

    2010-05-01

    A novel emerging technique for the label-free analysis of nano particles including biomolecules using optical micro cavity resonance is being developed. Various schemes based on a mechanically fixed microspheres as well as microspheres melted by laser on the tip of a standard single mode fiber have been investigated to make further development for microbial application. Water solutions of ethanol, HCl, glucose, vitamin C and biotin have been used to test refractive index changes by monitoring the magnitude of the whispering gallery modes spectral shift. Particular efforts were made for effective fixing of the micro spheres in the water flow, an optimal geometry for micro resonance observation and material of microsphere the most appropriate for microbial application. Optical resonance in free micro spheres from PMMA fixed in micro channels produced by photolithography has been observed under the laser power of less then 1 microwatt. Resonance shifts of C reactive protein water solutions as well as albumin solutions in pure water and with HCl modelling blood have been investigated. Introducing controlled amount of glass gel nano particles into sensor microsphere surrounding were accompanied by both correlative resonance shift (400 nm in diameter) and total reconstruct of resonance spectra (57 nm in diameter). Developed schemes have been demonstrated to be a promising technology platform for sensitive, lab-on-chip type sensor of diagnostic tools for different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells as well as in different experimental contexts e.g. proteomics, genomics, drug discovery, and membrane studies.

  20. Effect of UV radiations to control particle size of Mn-Zn spinel ferrite nano-particles

    NASA Astrophysics Data System (ADS)

    Ameen Ramiza, F.; Ajmal, S. K.; Khan, M. B.; Nasim, A.; Jamil, Y.; Kashif, K.; Amira, S.

    2016-08-01

    MnxZn1-xFe2O4 (0.0 < x < 1.0) ferrite nano particles were synthesized for concentration varying from 0.27 to 0.87 to obtain chemically homogenous powder for obtaining fine particle size by co precipitation technique. Keeping in view the interest of scientists for particle size, the present work focus on the impact of UV radiation to control the particle size of prepared fine magnetic particles. The particles were digested for ninety minutes at a temperature of 90oC. The samples were divided into four equal quantities and were subjected to different doses of UV radiation. The chemically produced samples of Mn-Zn ferrite nano particles were analyzed by XRD which confirmed cubic spinel structure of the material. The average crystallite size (t), lattice parameter (a) and other structural parameters of UV-irradiated MnxZni-xFe2O4 spinel ferrite were calculated from XRD data. The spinel peak of the irradiated sample when compared with the control sample, shifted from 35.38 to 35.15. In few samples, additional peaks supporting the ferrite structure were also observed. The variation in the particle sizes observed for various doses of UV irradiation were in the range of 17.6 to 6.2 nm, whereas the particle size of the control was 8.82nm. The experiment was repeated for different concentrations, at the same digestion temperature and time revealed the similar results indicating that UV radiations can have a remarkable effect to control the phase and size of nano size fine magnetic ferrite particles. The present work successfully document the impact of UV to control the particle size.

  1. High saturation magnetization of γ-Fe2O3 nano-particles by a facile one-step synthesis approach

    PubMed Central

    Cao, Derang; Li, Hao; Pan, Lining; Li, Jianan; Wang, Xicheng; Jing, Panpan; Cheng, Xiaohong; Wang, Wenjie; Wang, Jianbo; Liu, Qingfang

    2016-01-01

    We have demonstrated the synthesis of γ-Fe2O3 nano-particles through a facile and novel calcination process in the air. There is no pH regulation, gas atmosphere, additive, centrifugation or other complicated procedures during the preparing process. A detailed formation process of the nano-particles is proposed, and DMF as a polar solvent may slower the reaction process of calcination. The structures, morphologies, and magnetic properties of γ-Fe2O3 nano-particles were investigated systematically, and the pure γ-Fe2O3 nano-particles obtained at 200 °C display uniform morphology good magnetic property. The saturation magnetization of obtained pure γ-Fe2O3 is about 74 emu/g, which is comparable with bulk material (76 emu/g) and larger than other results. In addition, the photocatalytic activity for degradation of methylene blue is also studied, which shows proper photocatalytic activity. PMID:27581732

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

    PubMed Central

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

    2015-01-01

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

  3. Effects of Al2O3 Nano-Particles on Corrosion Performance of Plasma Electrolytic Oxidation Coatings Formed on 6061 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Vakili-Azghandi, Mojtaba; Fattah-alhosseini, Arash; Keshavarz, Mohsen K.

    2016-12-01

    Corrosion resistance improvement of plasma electrolyte oxidation coatings on 6061 aluminum alloy in silicate electrolyte containing Al2O3 nano-particles was studied, with particular emphasis on the microstructure, coating growth, and corrosion behavior in 3.5 wt.% NaCl solution. The microstructure of coatings, their thickness, and phase composition were characterized using scanning electron microscopy and x-ray diffraction. All characterization data showed that the maximum coating thickness and lowest amount of porosity were obtained in a low concentration of KOH, a high concentration of Na2SiO3, and moderate concentration of Al2O3 nano-particles in the electrolyte. This combination describes the optimum plasma electrolytic oxidation electrolyte, which has the best conductivity and oxidizing state, as well as the highest incorporation of electrolyte components in the coating growth process. On the other hand, incorporation and co-deposition of Al2O3 nano-particles were more pronounced than SiO3 2- ions in some level of molar concentration, which is due to the higher impact of electron discharge force on the adsorption of Al2O3 nano-particles. The electrochemical results showed that the best protective behavior was obtained in the sample having a coat with the lowest porosity and highest thickness.

  4. Biogenic Magnetite and EMF Effects

    NASA Astrophysics Data System (ADS)

    Kirschvink, Joseph L.

    1996-03-01

    Magnetite biomineralization is a genetically-controlled biochemical process through which organisms make perfect ferrimagnetic crystals, usually of single magnetic domain size. This process is an ancient one, having evolved about 2 billion years ago in the magnetotactic bacteria, and presumably was incorporated in the genome of higher organisms, including humans. During this time, DNA replication, protein synthesis, and many other biochemical processes have functioned in the presence of strong static fields of up to 400 mT adjacent to these magnetosomes without any obvious deleterious effects. Recent behavioral experiments using short but strong magnetic pulses in honeybees and birds demonstrates that ferromagnetic materials are involved in the sensory transduction of geomagnetic field information to the nervous system, and both behavioral and direct electrophysiological experiments indicate sensitivity thresholds to DC magnetic fields down to a few nT. However, far more biogenic magnetite is present in animal tissues than is needed for magnetoreception, and the biological function of this extra material is unknown. The presence of ferromagnetic materials in biological systems could provide physical transduction mechanisms for ELF magnetic fields, as well for microwave radiation in the .5 to 10 GHz band where magnetite has its peak ferromagnetic resonance. Elucidation of the cellular ultrastructure and biological function(s) of magnetite might help resolve the question of whether anthropogenic EMFs can cause deleterious biological effects. This work has been supported by grants from the NIH and EPRI.

  5. Micro-CT molecular imaging of tumor angiogenesis using a magnetite nano-cluster probe.

    PubMed

    Liu, Ping; Li, Jing; Zhang, Chunfu; Xu, Lisa X

    2013-06-01

    Due to its high resolution, micro-CT is desirable for molecular imaging of tumor angiogenesis. However, the sensitivity of micro-CT to contrast agents is relatively low. Therefore, the purpose of this study is to develop high micro-CT sensitive molecular imaging probes for direct visualization and dynamic monitoring of tumor angiogenesis. To this end, Arg-Gly-Asp (RGD) peptides conjugated magnetite nano clusters (RGD-MNCs) were developed by assembling individual magnetite nano particles into clusters with amphiphilic (maleimide) methoxypoly(ethylene glycol)-b-poly(lactic acid) ((Mal)mPEG-PLA) copolymer and subsequently encoding RGD peptides onto the clusters for specific targeting alpha(v)beta3 integrin. The hydrodynamic size of RGD-MNCs was about 85 nm. To test its specificity, alpha(v)beta3 positive cells (H1299) were incubated with magnetite nano clusters (MNCs), RGD-MNCs or RGD-MNCs competition with free RGD peptides. Prussian Blue staining and inductively coupled plasma optical emission spectrometer (ICP-OES) measurements indicated that the cell uptake of RGD-MNCs was significantly more than that of MNCs, which could be inhibited by free RGD peptides. For detection of tumor angiogenesis, mice bearing H1299 tumors were injected intravenously with RGD-MNCs at the dose of 400 micro mol Fe/kg. Tumor angiogenic hot spots as well as individual angiogenic vessels could be clearly manifested by micro-CT imaging 12 h post injection, which was dynamically monitored with the extension of probe circulation time. Subsequent histological studies of tumor tissues verified that RGD-MNCs registered tumor angiogenic vessels. Our study demonstrated that RGD-MNC probes fabricated in this study could be used to effectively target alpha(v)beta3 integrin. Using high resolution micro-CT in combination with the probes, tumor angiogenesis could be studied dynamically.

  6. Preparing a magnetically responsive single-wall carbon nanohorn colloid by anchoring magnetite nanoparticles.

    PubMed

    Utsumi, Shigenori; Urita, Koki; Kanoh, Hirofumi; Yudasaka, Masako; Suenaga, Kazutomo; Iijima, Sumio; Kaneko, Katsumi

    2006-04-13

    A single-wall carbon nanohorn (SWNH) colloid was made to be magnetically responsive by anchoring magnetite nanoparticles prepared by the homogeneous mixing of FeCl(2)-FeCl(3) and NaOH solutions. Transmission electron microscopy observation showed the high dispersion of magnetite particles of 2-9 nm on the surface of the SWNH colloid, coinciding with the broad X-ray diffraction peaks of the magnetites. The magnetization measurements showed that the magnetite nanoparticles-anchored SWNH (mag-SWNH) colloid has the hybrid property of ferrimagnetism and superparamagnetism. It was demonstrated that mag-SWNH colloid dispersed in water by sonication responded to an external magnetic field, gathering toward a magnet. N(2) adsorption experiments showed the high nanoporosity of mag-SWNHs and that magnetite nanoparticles were preferably anchored at "nanowindow" sites and the entrance sites of interstitial pores. This magnetically responsive SWNH colloid should contribute to the field of drug delivery.

  7. Renewable hybrid nanocatalyst from magnetite and cellulose for treatment of textile effluents.

    PubMed

    Arantes, Ana Carolina Cunha; Almeida, Crislaine das Graças; Dauzacker, Ligiane Carolina Leite; Bianchi, Maria Lucia; Wood, Delilah F; Williams, Tina G; Orts, William J; Tonoli, Gustavo Henrique Denzin

    2017-05-01

    A hybrid catalyst was prepared using cellulose nanofibrils and magnetite to degrade organic compounds. Cellulose nanofibrils were isolated by mechanical defibrillation producing a suspension used as a matrix for magnetite particles. The solution of nanofibrils and magnetite was dried and milled resulting in a catalyst with a 1:1 ratio of cellulose and magnetite that was chemically and physically characterized using light, scanning electron and transmission electron microscopies, specific surface area analysis, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, catalytic potential and degradation kinetics. Results showed good dispersion of the active phase, magnetite, in the mat of cellulosic nanofibrils. Leaching and re-use tests showed that catalytic activity was not lost over several cycles. The hybrid material produced was tested for degradation of methylene blue dye in Fenton-like reactions resulting in a potential catalyst for use in degradation of organic compounds.

  8. Magnetic microbes: Bacterial magnetite biomineralization

    DOE PAGES

    Prozorov, Tanya

    2015-09-14

    Magnetotactic bacteria are a diverse group of prokaryotes with the ability to orient and migrate along the magnetic field lines in search for a preferred oxygen concentration in chemically stratified water columns and sediments. These microorganisms produce magnetosomes, the intracellular nanometer-sized magnetic crystals surrounded by a phospholipid bilayer membrane, typically organized in chains. Magnetosomes have nearly perfect crystal structures with narrow size distribution and species-specific morphologies, leading to well-defined magnetic properties. As a result, the magnetite biomineralization in these organisms is of fundamental interest to diverse disciplines, from biotechnology to astrobiology. As a result, this article highlights recent advances inmore » the understanding of the bacterial magnetite biomineralization.« less

  9. Dissolution and reduction of magnetite by bacteria

    NASA Technical Reports Server (NTRS)

    Kostka, J. E.; Nealson, K. H.

    1995-01-01

    Magnetite (Fe3O4) is an iron oxide of mixed oxidation state [Fe(II), Fe(III)] that contributes largely to geomagnetism and plays a significant role in diagenesis in marine and freshwater sediments. Magnetic data are the primary evidence for ocean floor spreading and accurate interpretation of the sedimentary magnetic record depends on an understanding of the conditions under which magnetite is stable. Though chemical reduction of magnetite by dissolved sulfide is well known, biological reduction has not been considered likely based upon thermodynamic considerations. This study shows that marine and freshwater strains of the bacterium Shewanella putrefaciens are capable of the rapid dissolution and reduction of magnetite, converting millimolar amounts to soluble Fe(II)in a few days at room temperature. Conditions under which magnetite reduction is optimal (pH 5-6, 22-37 degrees C) are consistent with an enzymatic process and not with simple chemical reduction. Magnetite reduction requires viable cells and cell contact, and it appears to be coupled to electron transport and growth. In a minimal medium with formate or lactate as the electron donor, more than 10 times the amount of magnetite was reduced over no carbon controls. These data suggest that magnetite reduction is coupled to carbon metabolism in S. putrefaciens. Bacterial reduction rates of magnetite are of the same order of magnitude as those estimated for reduction by sulfide. If such remobilization of magnetite occurs in nature, it could have a major impact on sediment magnetism and diagenesis.

  10. Dissolution and reduction of magnetite by bacteria.

    PubMed

    Kostka, J E; Nealson, K H

    1995-10-01

    Magnetite (Fe3O4) is an iron oxide of mixed oxidation state [Fe(II), Fe(III)] that contributes largely to geomagnetism and plays a significant role in diagenesis in marine and freshwater sediments. Magnetic data are the primary evidence for ocean floor spreading and accurate interpretation of the sedimentary magnetic record depends on an understanding of the conditions under which magnetite is stable. Though chemical reduction of magnetite by dissolved sulfide is well known, biological reduction has not been considered likely based upon thermodynamic considerations. This study shows that marine and freshwater strains of the bacterium Shewanella putrefaciens are capable of the rapid dissolution and reduction of magnetite, converting millimolar amounts to soluble Fe(II)in a few days at room temperature. Conditions under which magnetite reduction is optimal (pH 5-6, 22-37 degrees C) are consistent with an enzymatic process and not with simple chemical reduction. Magnetite reduction requires viable cells and cell contact, and it appears to be coupled to electron transport and growth. In a minimal medium with formate or lactate as the electron donor, more than 10 times the amount of magnetite was reduced over no carbon controls. These data suggest that magnetite reduction is coupled to carbon metabolism in S. putrefaciens. Bacterial reduction rates of magnetite are of the same order of magnitude as those estimated for reduction by sulfide. If such remobilization of magnetite occurs in nature, it could have a major impact on sediment magnetism and diagenesis.

  11. Fluid-induced martitization of magnetite in BIFs from the Dharwar Craton, India.

    NASA Astrophysics Data System (ADS)

    Wagner, Christiane; Orberger, Beate; Tudryn, Alina; Wirth, Richard; Morgan, Rachael

    2013-04-01

    the formation of maghemite at the interface between magnetite and hematite with the migration of excess Fe3+ through the magnetite crystal lattice to the surface. Martitization is thus due to hydrothermal events associated with grain boundary migration during dynamic recrystallization.

  12. Microwave heating characteristics of magnetite ore

    NASA Astrophysics Data System (ADS)

    Rajavaram, Ramaraghavulu; Lee, Jaehong; Oh, Joon Seok; Kim, Han Gyeol; Lee, Joonho

    2016-11-01

    The heating characteristics of magnetite ore under microwave irradiation were investigated as a function of incident microwave power, particle size, and magnetite ore mass. The results showed that the heating rate of magnetite ore is highly dependent on microwave power and magnetite ore mass. The maximum heating rate was obtained at a microwave irradiation power of 1.70 kW with a mass of 25 g and particle size between 53-75 µm. The volumetric heating rate of magnetite ore was investigated by measuring the temperature at different depths during microwave irradiation. Microwave irradiation resulted in modification of the microstructure of the magnetite ore, but new phases such as FeO or Fe2O3 were not formed. In addition, the crystal size decreased from 115 nm to 63 nm after microwave irradiation up to 1573 K.

  13. Removal of azo dye from water by magnetite adsorption-Fenton oxidation.

    PubMed

    Rongcheng, Wu; Jiuhui, Qu

    2004-01-01

    The aim of this study is to highlight the possibility of using powder magnetite adsorption-Fenton oxidation as a method for removal of azo dye acid red B (ARB) from water. The adsorption properties of magnetite powder towards ARB were studied. The oxidation of adsorbed ARB and regeneration of magnetite adsorbent at the same time by Fenton reagent (hydrogen peroxide [H2O2] + iron (II) [Fe2+]) in another treatment unit with a smaller volume was also investigated. The efficiency of Fenton oxidation of ARB was compared for the reaction carried out in solution and on magnetite. The magnetic separation method was used to recover magnetite after adsorption or regeneration. The results indicated that the adsorption rate was fast. The capacity was strongly dependent on pH and inorganic anions, and pH 3.8 was optimal for the adsorption of ARB. The adsorption can be described well using the Langmuir model. The oxidation was more efficient for ARB adsorbed on magnetite than in solution. The adsorption capacity of magnetite increased significantly after regeneration, which was the result of an increase in surface area of the adsorbent and change of elemental ratio (oxygen:iron [O:Fe]) on the surface. The maximum adsorption capacity for ARB was 32.4 mg/g adsorbent.

  14. Characterization Of Environmentally Relevant Chemical And Physical Properties Of Silver Nano-Particles

    EPA Science Inventory

    Understanding and predicting the fate and transport of nano-materials in the environment requires a detailed characterization of the chemical and physical properties that control fate and transport. In the current study, we have evaluated the surface charge, aggregation potentia...

  15. Accurate optical simulation of nano-particle based internal scattering layers for light outcoupling from organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Egel, Amos; Gomard, Guillaume; Kettlitz, Siegfried W.; Lemmer, Uli

    2017-02-01

    We present a numerical strategy for the accurate simulation of light extraction from organic light emitting diodes (OLEDs) comprising an internal nano-particle based scattering layer. On the one hand, the light emission and propagation through the OLED thin film system (including the scattering layer) is treated by means of rigorous wave optics calculations using the T-matrix formalism. On the other hand, the propagation through the substrate is modeled in a ray optics approach. The results from the wave optics calculations enter in terms of the initial substrate radiation pattern and the bidirectional reflectivity distribution of the OLED stack with scattering layer. In order to correct for the truncation error due to a finite number of particles in the simulations, we extrapolate the results to infinitely extended scattering layers. As an application example, we estimate the optimal particle filling fraction for an internal scattering layer in a realistic OLED geometry. The presented treatment is designed to emerge from electromagnetic theory with as few additional assumptions as possible. It could thus serve as a baseline to validate faster but approximate simulation approaches.

  16. Application of the PAMONO-Sensor for Quantification of Microvesicles and Determination of Nano-Particle Size Distribution

    PubMed Central

    Shpacovitch, Victoria; Sidorenko, Irina; Lenssen, Jan Eric; Temchura, Vladimir; Weichert, Frank; Müller, Heinrich; Überla, Klaus; Zybin, Alexander; Schramm, Alexander; Hergenröder, Roland

    2017-01-01

    The PAMONO-sensor (plasmon assisted microscopy of nano-objects) demonstrated an ability to detect and quantify individual viruses and virus-like particles. However, another group of biological vesicles—microvesicles (100–1000 nm)—also attracts growing interest as biomarkers of different pathologies and needs development of novel techniques for characterization. This work shows the applicability of a PAMONO-sensor for selective detection of microvesicles in aquatic samples. The sensor permits comparison of relative concentrations of microvesicles between samples. We also study a possibility of repeated use of a sensor chip after elution of the microvesicle capturing layer. Moreover, we improve the detection features of the PAMONO-sensor. The detection process utilizes novel machine learning techniques on the sensor image data to estimate particle size distributions of nano-particles in polydisperse samples. Altogether, our findings expand analytical features and the application field of the PAMONO-sensor. They can also serve for a maturation of diagnostic tools based on the PAMONO-sensor platform. PMID:28134825

  17. Dispensing of high concentration Ag nano-particles ink for ultra-low resistivity paper-based writing electronics.

    PubMed

    Wang, Fuliang; Mao, Peng; He, Hu

    2016-02-17

    Paper-based writing electronics has received a lot of interest recently due to its potential applications in flexible electronics. To obtain ultra-low resistivity paper-based writing electronics, we developed a kind of ink with high concentration of Ag Nano-particles (up to 80 wt%), as well as a related dispensing writing system consisting an air compressor machine and a dispenser. Additionally, we also demonstrated the writability and practical application of our proposed ink and writing system. Based on the study on the effect of sintering time and pressure, we found the optimal sintering time and pressure to obtain high quality Ag NPs wires. The electrical conductivity of nano-silver paper-based electronics has been tested using the calculated resistivity. After hot-pressure sintering at 120 °C, 25 MPa pressure for 20 minutes, the resistivity of silver NPs conductive tracks was 3.92 × 10(-8) (Ωm), only 2.45 times of bulk silver. The mechanical flexibility of nano-silver paper-based electronics also has been tested. After 1000 bending cycles, the resistivity slightly increased from the initial 4.01 × 10(-8) to 5.08 × 10(-8) (Ωm). With this proposed ink preparation and writing system, a kind of paper-based writing electronics with ultra-low resistivity and good mechanical flexibility was achieved.

  18. The role of silver nano-particles and silver thiosulfate on the longevity of cut carnation (Dianthus caryophyllus) flowers.

    PubMed

    Hashemabadi, Davood

    2014-07-01

    The purpose of this study was to evaluate the efficacy of silver nano-particles (SNP) and silver thiosulfate (STS) in extending the vase life of cut carnation (Dianthus caryophyllus L. cv. 'Tempo') flowers. Pulse treatments of SNP @ 0, 5, 10 and 15 mg l(-1) and STS @ 0, 0.1, 0.2 and 0.3 mM were administered to carnation flowers for 24 hr. The longest vase life (16.1 days) was observed in flowers treated with 15 mg l(-1) of SNP + 0.2 mM STS. The least chlorophyll was destroyed in flowers treated with 15 mg I(-1) of SNP + 0.3 mM STS. Our findings showed that the 15 mg l(-1) SNP treatment inhibited bacterial growth in the preservative solution. The control flowers bloomed faster than the treated flowers. The maximum peroxidase activity and the minimum lipid peroxidation were obtained in cut flowers that were treated with 15 mg l(-1) of SNP and 0.3 mM STS. Overall, results of the study revealed that SNP and STS treatment extended the longevity of cut carnation 'Tempo' flowers by reducing oxidative stress, improving anti-oxidant system, reducing bacterial populations and delaying flowering.

  19. Application of the PAMONO-Sensor for Quantification of Microvesicles and Determination of Nano-Particle Size Distribution.

    PubMed

    Shpacovitch, Victoria; Sidorenko, Irina; Lenssen, Jan Eric; Temchura, Vladimir; Weichert, Frank; Müller, Heinrich; Überla, Klaus; Zybin, Alexander; Schramm, Alexander; Hergenröder, Roland

    2017-01-27

    The PAMONO-sensor (plasmon assisted microscopy of nano-objects) demonstrated an ability to detect and quantify individual viruses and virus-like particles. However, another group of biological vesicles-microvesicles (100-1000 nm)-also attracts growing interest as biomarkers of different pathologies and needs development of novel techniques for characterization. This work shows the applicability of a PAMONO-sensor for selective detection of microvesicles in aquatic samples. The sensor permits comparison of relative concentrations of microvesicles between samples. We also study a possibility of repeated use of a sensor chip after elution of the microvesicle capturing layer. Moreover, we improve the detection features of the PAMONO-sensor. The detection process utilizes novel machine learning techniques on the sensor image data to estimate particle size distributions of nano-particles in polydisperse samples. Altogether, our findings expand analytical features and the application field of the PAMONO-sensor. They can also serve for a maturation of diagnostic tools based on the PAMONO-sensor platform.

  20. Decoration of cesium iodide nano particles on patterned carbon nanotube emitter arrays to improve their field emission

    NASA Astrophysics Data System (ADS)

    Shahi, Monika; Gautam, S.; Shah, P. V.; Rawat, J. S.; Chaudhury, P. K.; Harsh; Tandon, R. P.

    2013-03-01

    Arrays of aligned carbon nanotube (CNT) bundles were synthesized on the pre-patterned silicon substrate using thermal chemical vapor deposition. Silicon substrate was patterned with square arrays of 10 × 10 μm iron catalyst using photolithography, iron sputtering, and a lift-off process. After field emission (FE) measurement in diode configuration, CNT emitter arrays (CEAs) were decorated with cesium iodide (CsI) nano particles (NPs) using thermal evaporation with substrate heating at 300 °C. FE of pristine CEAs and CsI NPs decorated CEAs were carried out under same vacuum condition and constant inter-electrode separation. Pristine CEAs and CsI NPs decorated CEAs were characterized using scanning electron microscope, transmission electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Raman characterization. From FE comparison plots, it was observed that CsI NPs decoration on the CEAs had significantly lowered the turn-on electric field from 3.00 to 2.13 V/μm. A remarkable improvement of more than 50 % in the current density, from 11.02 to 17.33 mA/cm2, was also observed at a constant applied electric field of 5 V/μm.

  1. Studying Physical Properties at the Nano-Scale: Thin Films, Nano-Particles and Molecules

    NASA Astrophysics Data System (ADS)

    Eisenstein, Alon

    Nanomaterials have been shown to be useful for many applications. The characterization of nanomaterials is a crucial step in understanding how to control their performance to tailor their properties for desired applications. In this thesis, several nanomaterials were studied using various methods, in an effort to characterize their properties. In the first chapter, the initial growth steps of nanometer thick polyelectrolyte film, grown layer-by-layer, were studied using Kelvin Probe Force Microscopy. The initially small domains grew with each added layer. Surface potential contrast enabled the visualization of these domains far beyond the point where no topographical variation was visible. In the second and third chapters, the potential of using collapsed-polymer nanoparticles as a carrier platform for active chemicals was studied using dye molecules as probes. Two methods were implemented, spectroscopy and isothermal titration calorimetry. Following the measurements, a binding model was proposed, which also provided thermodynamic quantification of the binding process. In the fourth chapter, an atomic force microscope probe holder was custom designed and built to enable characterization of the probes using scanning electron microscopy in an effort to facilitate specific identification of composite collapsed-polymer nanoparticles using tip-enhanced Raman Spectroscopy. In the fifth chapter, an ultra high vacuum gas dosing attachment was custom designed and built to enable a study of self-assembly of organic molecules on silicon surface. Pulse dosing was found to affect the self-assembled pattern on the surface. In the final chapter, the surface halogenation of copper surfaces was studied using a scanning tunneling microscope. The reaction was induced by an electron pulse. The scattered halogens, dissociated from the initial molecule, provided information regarding the reaction dynamics of the process.

  2. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination

    PubMed Central

    Dai, Bin; Wang, Qinqin; Yu, Feng; Zhu, Mingyuan

    2015-01-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au3+ reduction to metallic Au0 is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction time. The results indicated that metallic Au0 exhibits considerable catalytic activity and that Au nano-particle aggregation may be another reason for the AuCl3/AC catalytic activity in acetylene hydrochlorination. PMID:25994222

  3. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination

    NASA Astrophysics Data System (ADS)

    Dai, Bin; Wang, Qinqin; Yu, Feng; Zhu, Mingyuan

    2015-05-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au3+ reduction to metallic Au0 is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction time. The results indicated that metallic Au0 exhibits considerable catalytic activity and that Au nano-particle aggregation may be another reason for the AuCl3/AC catalytic activity in acetylene hydrochlorination.

  4. Benefaction studies on the Hasan Celebi magnetite deposit, Turkey

    USGS Publications Warehouse

    Pressler, Jean W.; Akar, Ali

    1972-01-01

    Bench-scale and semicontinuous tests were performed on surface, trench, and diamond drill core samples from the Hasan Celebi low-grade magnetite deposit to determine the optimum benefication procedures utilizing wet magnetic separation techniques. Composite core samples typically contain about 27 percent recoverable magnetite and require crushing and grinding through 1 mm in size to insure satisfactory separation of the gangue from the magnetite. Regrinding and cleaning the magnetite concentrate to 80 percent minus 150-mesh is necessary to obtain an optimum of 66 percent iron. Semicontinuous pilot-plant testing with the wet magnetic drum using the recycled middling technique indicates that as much as 83 percent of the acid-soluble iron can be recovered into a concentrate containing 66 percent iron, with minimum deleterious elements. This represents 27 weight percent of the original ore. Further tests will continue when the Maden Tetkik ve Arama Enstitusu (MTA) receives 24 tons of bulk sample from an exploratory drift and cross-cut now being driven through a section of the major reserve area.

  5. Novel Nano-particle, Temperature-Independent Damping System: Basic Science and Applications

    DTIC Science & Technology

    2009-12-31

    the mechanical components of the dampers are filled with selected particles. The advantages of particle damping over the conventional damping...temperature ranges. 2. The particle size is much smaller than the scale of the container surface roughness, therefore the particles will fill the...For thrust damping or radial damping, the mechanical components of the dampers are filled with properly selected nanoparticles. -U- Vertical

  6. Uranium reduction on magnetite: Probing for pentavalent uranium using electrochemical methods

    NASA Astrophysics Data System (ADS)

    Yuan, Ke; Renock, Devon; Ewing, Rodney C.; Becker, Udo

    2015-05-01

    Pentavalent uranium is generally treated as an unstable intermediate when uranyl, U(VI)O22+, is reduced to U4+. However, mineral surfaces have been shown to stabilize pentavalent uranium, thus hindering further reduction (Ilton et al., 2005, 2010). The subject of this study is to identify the kinetic pathways that lead to U(V)O2+ being a metastable species. Electrochemical methods provide an in situ approach for the investigation of the intermediate reaction of U(V)O2+ on the surfaces of magnetite. Redox reactions of uranyl ions on particulate (∼3 μm) and bulk magnetite surfaces were investigated using cyclic voltammetry and potential step chronoamperometry using cavity microelectrodes and bulk (planar) mineral electrodes. The estimated redox potentials are consistent with the standard redox potential of UO22+/UO2+, indicating UO22+ is first reduced to UO2+ on the surfaces of both powder and bulk magnetite. The one-electron reduction of UO22+ to UO2+ was further confirmed by directly measuring the number of electrons transferred during the reduction process on the bulk magnetite electrode. Based on the charge conservation analysis and the positive correlation between the pH and the peak current for the UO2+ transformation to UO22+, the peak corresponding to the oxidation of U4+ to UO22+ was assigned in the voltammograms of particulate magnetite. The presence of U4+ indicates that the disproportionation of UO2+ (2U(V) ↔ U(IV) + U(VI)) is occurring on the surface of particulate magnetite within the timeframe of the experiment. The lack of a peak for U4+ in voltammograms for bulk magnetite suggests that the rate of the UO2+ disproportionation reaction is slower on bulk magnetite than that on particulate magnetite. The catalytic property of particulate magnetite surfaces on the disproportionation reaction is explained by its ability to adsorb and desorb protons, which could facilitate the proton-coupled disproportionation reaction of UO2+. This increased catalytic

  7. Synthesis of single phase. alpha. -Fe, Fe sub 3 C and Fe sub 7 C sub 3 nano-particles by CO sub 2 laser pyrolysis technique

    SciTech Connect

    Eklund, P.C.; Bi, X.X.

    1992-01-01

    Iron-containing catalysts have been known to be useful in assisting the Fischer-Tropsch (FT) reaction for synthesizing hydrocarbons. However, it has been well recognized that iron catalyst are not stable during the reaction but converted into iron carbides. It is thus important to understand the role of the iron carbides in the catalytic reaction of the FT-synthesis. It has been found difficult to produce iron carbide nano-particles as a single phase, because iron carbide phases are only metastable under 1 atm pressure. Iron carbide bulk particles prepared so far are often contaminated with metallic iron, iron oxides and free carbon. In this study, we investigate the synthesis of iron carbide nano-particles using CO{sub 2} laser pyrolysis technique. We show that this technique is successful in synthesizing {alpha}-Fe, Fe{sub 3}C and Fe{sub 7}C{sub 3} nano-particles in their single phase with sizes in the range of 5--20nm. In particular, we have produced for the first time the Fe{sub 7}C{sub 3} which has been known to exist but unable to be produced as a single phase. Furthermore, it is interesting that Fe{sub 5}C{sub 2} which has carbon and iron ratio between Fe{sub 3}C and Fe{sub 7}C{sub 3}, is not seen in any run of our synthesis.

  8. Analysis and Application of Silicon Nano-Particles Produced via Continuous Flow Non-Thermal Plasmas

    NASA Astrophysics Data System (ADS)

    Lopez, Thomas David

    Continuous flow non-thermal plasma reactors are being investigated for their ability to efficiently produce high quality nanoparticles. While many nanomaterials can be produced via continuous flow non-thermal plasma reactors, silicon is of particular interest, due to its abundance and relevance in many energy related fields. Significant gaps still exist in the understanding of the kinetics responsible for particle growth, structural evolution, and surface termination of continuous flow non-thermal plasma reactor produced particles. Particle interaction with plasma radicals results in the heating of the particles, which in turn affects the kinetics of particle growth, structural evolution, and surface termination during synthesis and processing. We have investigated the details of plasma-nanoparticle interaction by using in-flight and in-situ characterization techniques. For the first time, we have measured the temperature of a free-standing particle immersed in a non-equilibrium processing plasma. In parallel, we have utilized continuous flow non-thermal plasma reactor-produced nanoparticles to create bulk nanostructured materials. The ability to tune size, structure, and surface termination of the continuous flow non-thermal plasma reactor produced nanoparticles allows for significant control of the precursor powders used in the densification processes. Hot pressing processes allow for the production of samples with bulk-like densities while limiting grain growth, allowing for the creation of nanostructured bulk systems. Nanostructured bulk silicon represents an ideal system to study the role of nano-structuring on transport of charge carriers and phonons in bulk materials. Initial results show that small particle and narrow particle size distributions allows for the creation of bulk nanostructured silicon with high ZT values. This system has shown to be relevant for direct conversion of heat into electrical power, but is also a model for the optimization of

  9. Dependence of microbial magnetite formation on humic substance and ferrihydrite concentrations

    NASA Astrophysics Data System (ADS)

    Piepenbrock, Annette; Dippon, Urs; Porsch, Katharina; Appel, Erwin; Kappler, Andreas

    2011-11-01

    Iron mineral (trans)formation during microbial Fe(III) reduction is of environmental relevance as it can influence the fate of pollutants such as toxic metal ions or hydrocarbons. Magnetite is an important biomineralization product of microbial iron reduction and influences soil magnetic properties that are used for paleoclimate reconstruction and were suggested to assist in the localization of organic and inorganic pollutants. However, it is not well understood how different concentrations of Fe(III) minerals and humic substances (HS) affect magnetite formation during microbial Fe(III) reduction. We therefore used wet-chemical extractions, magnetic susceptibility measurements and X-ray diffraction analyses to determine systematically how (i) different initial ferrihydrite (FH) concentrations and (ii) different concentrations of HS (i.e. the presence of either only adsorbed HS or adsorbed and dissolved HS) affect magnetite formation during FH reduction by Shewanella oneidensis MR-1. In our experiments magnetite formation did not occur at FH concentrations lower than 5 mM, even though rapid iron reduction took place. At higher FH concentrations a minimum fraction of Fe(II) of 25-30% of the total iron present was necessary to initiate magnetite formation. The Fe(II) fraction at which magnetite formation started decreased with increasing FH concentration, which might be due to aggregation of the FH particles reducing the FH surface area at higher FH concentrations. HS concentrations of 215-393 mg HS/g FH slowed down (at partial FH surface coverage with sorbed HS) or even completely inhibited (at complete FH surface coverage with sorbed HS) magnetite formation due to blocking of surface sites by adsorbed HS. These results indicate the requirement of Fe(II) adsorption to, and subsequent interaction with, the FH surface for the transformation of FH into magnetite. Additionally, we found that the microbially formed magnetite was further reduced by strain MR-1 leading to

  10. Montmorillonite-supported magnetite nanoparticles for the removal of hexavalent chromium [Cr(VI)] from aqueous solutions.

    PubMed

    Yuan, Peng; Fan, Mingde; Yang, Dan; He, Hongping; Liu, Dong; Yuan, Aihua; Zhu, JianXi; Chen, TianHu

    2009-07-30

    Montmorillonite-supported magnetite nanoparticles were prepared by co-precipitation and hydrosol method. The obtained materials were characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the magnetite nanoparticles without and with montmorillonite support are around 25 and 15 nm, respectively. The montmorillonite-supported magnetite nanoparticles exist on the surface or inside the interparticle pores of clays, with better dispersing and less coaggregation than the ones without montmorillonite support. Batch tests were carried out to investigate the removal mechanism of hexavalent chromium [Cr(VI)] by these synthesized magnetite nanoparticles. The Cr(VI) uptake was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed the Pseudo-second-order model. The adsorption data of unsupported and clay-supported magnetite nanoparticles fit well with the Langmuir and Freundlich isotherm equations. The montmorillonite-supported magnetite nanoparticles showed a much better adsorption capacity per unit mass of magnetite (15.3mg/g) than unsupported magnetite (10.6 mg/g), and were more thermally stable than their unsupported counterparts. These fundamental results demonstrate that the montmorillonite-supported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.

  11. Magnetism of Al-substituted magnetite reduced from Al-hematite

    NASA Astrophysics Data System (ADS)

    Jiang, Zhaoxia; Liu, Qingsong; Zhao, Xiang; Roberts, Andrew P.; Heslop, David; Barrón, Vidal; Torrent, José

    2016-06-01

    Aluminum-substituted magnetite (Al-magnetite) reduced from Al-substituted hematite or goethite (Al-hematite or Al-goethite) is an environmentally important constituent of magnetically enhanced soils. In order to characterize the magnetic properties of Al-magnetite, two series of Al-magnetite samples were synthesized through reduction of Al-hematite by a mixed gas (80% CO2 and 20% CO) at 395°C for 72 h in a quartz tube furnace. Al-magnetite samples inherited the morphology of their parent Al-hematite samples, but only those transformed from Al-hematite synthesized at low temperature possessed surficial micropores, which originated from the release of structural water during heating. Surface micropores could thus serve as a practical fingerprint of fire or other high-temperature mineralogical alteration processes in natural environments, e.g., shear friction in seismic zones. In addition, Al substitution greatly affects the magnetic properties of Al-magnetite. For example, coercivity (Bc) increases with increasing Al content and then decreases slightly, while the saturation magnetization (Ms), Curie temperature (Tc), and Verwey transition temperature (Tv) all decrease with increasing Al content due to crystal defect formation and dilution of magnetic ions caused by Al incorporation. Moreover, different trends in the correlation between Tc and Bc can be used to discriminate titanomagnetite from Al-magnetite, which is likely to be important in environmental and paleomagnetic studies, particularly in soil.

  12. Antimicrobial Properties of Lysosomal Enzymes Immobilized on NH₂Functionalized Silica-Encapsulated Magnetite Nanoparticles.

    PubMed

    Bang, Seung Hyuck; Sekhon, Simranjeet Singh; Cho, Sung-Jin; Kim, So Jeong; Le, Thai-Hoang; Kim, Pil; Ahn, Ji-Young; Kim, Yang-Hoon; Min, Jiho

    2016-01-01

    The immobilization efficiency, antimicrobial activity and recovery of lysosomal enzymes on NH2 functionalized magnetite nanoparticles have been studied under various conditions. The immobi- lization efficiency depends upon the ratio of the amount of enzyme and magnetite and it shows an increase with magnetite concentration which is due to the presence of amine group at the magnetite surface that leads to a strong attraction. The optimized reaction time to immobilize the lysosomal enzymes on magnetite was determined by using a rolling method. The immobilization efficiency increases with reaction time and reached a plateau after 5 minutes and then remained constant for 10 minutes. However, after 30 minutes the immobilization efficiency decreased to 85%, which is due to the weaker electrostatic interactions between magnetite and detached lysosomal enzymes. The recovery and stability of immobilized lysosomal enzymes has also been studied. The antimicrobial activity was almost 100% but it decreased upon reuse and no activity was observed after its reuse for seven times. The storage stability of lysosomal enzymes as an antimicrobial agent was about 88%, which decreased to 53% after one day and all activity of immobilized lysosomal enzymes was maintained after five days. Thus, the lysosomal enzymes immobilized on magnetite nanoparticles could potentially be used as antimicrobial agents to remove bacteria.

  13. Application of gold nano-particles for silicon solar cells efficiency increase

    NASA Astrophysics Data System (ADS)

    Axelevitch, A.; Gorenstein, B.; Golan, G.

    2014-10-01

    The main problems preventing wide spreading of solar cells as alternative energy sources are their high cost and low efficiency. Efficiency of solar cells based on semiconductor materials is limited due to high electrical and optical losses and due to recombination processes. Non-continuous, thin island gold films deposited on a dielectric or semiconductor surface introduce a unique behavior. In response to light exposure in certain range, the metal islands present a resonant absorption of light accompanied with a collective behavior of free electrons in these islands. In this paper we present one possible way to increase the efficiency of solar cells by using nano-dimensional gold islands imbedded in semiconductor junctions.

  14. The use of visible light and metal oxide nano particles for pathogen inactivation

    NASA Astrophysics Data System (ADS)

    Lubart, R.; Lipovski, A.; Gedanken, A.

    2012-09-01

    Since the effectiveness of antibiotic treatment is decreasing due to the development of resistant strains, alternative approaches for destroying microorganisms are needed. In this review we summarize new technologies that might be effective for pathogen inactivation. In the past we found that intense blue light could be used for bacterial eradication. The phototoxic effect correlated with the amount of reactive oxygen species (ROS) generated by the bacteria due to illumination. Recently it has been shown that the effect of light can be enhanced by introducing metal oxide nanoparticles (nps) to the bacteria prior to irradiation. This led us to suggest combining nanoparticles with visible light irradiation for pathogen eradication. We have shown that combination of illumination with the nanoparticles (ZnO or TiO2) resulted in a marked increase in the reduction of bacterial viability to a mean reduction of 80-90% for both nanoaprticles. As a matter of fact metal oxide nps alone can be used for bacteria destruction. The advantage of our approach is the use of lower concentrations of nps, combined with reduced light intensity that is less toxic to the host tissue. To further avoid the toxicity of metal oxides nps on healthy tissue it is possible to coat their surfaces with various substrates including ceramics and polymers. Recently Zinc oxide nanoparticles have been synthesized and deposited on the surface of cotton fabrics using ultrasound irradiation. Thus in the future we will try to treat infected wounds with transparent bandages coated with ZnO that will be applied to the wounds prior to irradiation.

  15. Preparation of magnetite aqueous dispersion for magnetic fluid hyperthermia

    NASA Astrophysics Data System (ADS)

    Kikuchi, Teppei; Kasuya, Ryo; Endo, Shota; Nakamura, Akira; Takai, Toshiyuki; Metzler-Nolte, Nils; Tohji, Kazuyuki; Balachandran, Jeyadevan

    2011-05-01

    An aqueous magnetic suspension was prepared by dispersing amphiphilic co-polymer-coated monodispersed magnetite nanoparticles synthesized through thermal decomposition of iron acetylacetonate (Fe(acac) 3) in a mixture of oleic acid and oleylamine. The average diameter of narrow-size-distributed magnetite nanoparticles varied between 5 and 12 nm depending on the experimental parameters such as reaction temperature, metal salt concentration and oleic acid/oleylamine ratio. Though the as-synthesized particles were coated with oleate and were dispersible in organic solvent, their surfaces were modified using amphiphilic co-polymers composed of poly(maleic anhydride-alt-1-octadecene) and polyethylene glycol-methyl ether and made dispersible in water. Infrared spectra of the sample indicated the existence of -COOH groups on the surface for further conjugation with biomolecules for targeted cancer therapy.

  16. Nano-particle enhanced impedimetric biosensor for detedtion of foodborne pathogens

    NASA Astrophysics Data System (ADS)

    Kim, G.; Om, A. S.; Mun, J. H.

    2007-03-01

    Recent outbreaks of foodborne illness have been increased the need for rapid and sensitive methods for detection of these pathogens. Conventional methods for pathogens detection and identification involve prolonged multiple enrichment steps. Even though some immunological rapid assays are available, these assays still need enrichment steps result in delayed detection. Biosensors have shown great potential for rapid detection of foodborne pathogens. They are capable of direct monitoring the antigen-antibody reactions in real time. Among the biosensors, impedimetric biosensors have been widely adapted as an analysis tool for the study of various biological binding reactions because of their high sensitivity and reagentless operation. In this study a nanoparticle-enhanced impedimetric biosensor for Salmonella enteritidis detection was developed which detected impedance changes caused by the attachment of the cells to the anti-Salmonella antibodies immobilized on interdigitated gold electrodes. Successive immobilization of neutravidin followed by anti-Salmonella antibodies was performed to the sensing area to create a biological detection surface. To enhance the impedance responses generated by antigen-antibody reactions, anti-Salmonella antibody conjugated nanoparticles were introduced on the sensing area. Using a portable impedance analyzer, the impedance across the interdigital electrodes was measured after the series of antigen-antibody bindings. Bacteria cells present in solution attached to capture antibodies and became tethered to the sensor surface. Attached bacteria cells changed the dielectric constant of the media between the electrodes thereby causing a change in measured impedance. Optimum input frequency was determined by analyzing frequency characteristics of the biosensor over ranges of applied frequencies from 10 Hz to 400 Hz. At 100 Hz of input frequency, the biosensor was most sensitive to the changes of the bacteria concentration and this frequency

  17. The use of nano-particles to produce iridescent metallic effects on ancient ceramic objects.

    PubMed

    Fermo, P; Padeletti, G

    2012-11-01

    Nano-sized materials have been often used in the past to realize objects with particular characteristics. One of the most outstanding examples is represented by luster pottery, showing shining surfaces with particular optical properties. Luster was one of the most sophisticated technique for the decoration of majolicas. It consists of a thin metallic film containing silver, copper and other substances, like iron oxide and cinnabar, applied in a reducing atmosphere on a previously glazed ceramic. In such a way, beautiful iridescent reflections of different colours (in particular gold and ruby-red) are obtained. This technique, at first developed in Iraq, was introduced in Italy from Spain. In Italy the potters of the two centres of Gubbio and Deruta, in central Italy, became so expert that nowadays modern artisans are not able to reproduce the wonderful effects obtained during Renaissance. A complete characterization by means of numerous techniques has been carried out on a great number of shards and precious work of arts conserved in many important museums. This allowed to draw some correlations between the preparation technique and the obtained nano-structure.

  18. Enhanced x-ray emission from nano-particle doped bacteria.

    PubMed

    Krishnamurthy, M; Kundu, M; Bane, Kartik; Lad, Amit D; Singh, Prashant Kumar; Chatterjee, Gourab; Ravindra Kumar, G; Ray, Krishanu

    2015-07-13

    Recently, it has been greatly appreciated that intense light matter interaction is modified due to the nano- and microstructures in the target by--surface plasmons, laser energy localization scattering etc. Extreme laser intensities produce dense plasmas and collective mechanisms generate energetic electrons, ions and hard x-rays. Recently, it is postulated that the anharmonic electron motion, driven by ultrashort, high-intensity laser pulses, provides a universal mechanism for the laser absorption. Here, we provide the first demonstration of anharmonic-resonance-aided high laser-absorption in a biological system. At intensities of ∼ 10¹⁶⁻¹⁸ W/cm², 40 fs pulses excite a plasma formed with E. coli bacteria. The density-inhomogeneities due to the micro- and nanostructures in the bacterial target increase anharmonic resonance (AHR) heating and result in a 10⁴-fold enhancement in the hard x-ray yield compared to plain solid targets. These observations lead to novel high-energy x-ray sources that have implications to lithography, imaging and medical applications.

  19. Micro/nano-particle decorated metal wire for cutting soft matter

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Feng, Liang-liang; Wu, Fan; Zhang, Run-run; Wu, Cheng-wei

    2016-09-01

    To cut soft materials such as biological tissues with minimal damage and reduced positional error is highly desired in medical surgery and biomechanics. After years of natural selection and evolution, mosquitoes have acquired the ability to insert their proboscises into human skin with astonishingly tiny forces. This can be associated with the unique structure of their proboscises, with micro/nano sawteeth, and the distinctive insertion manner: high frequency reciprocating saw cutting. Inspired by these, this communication describes the successful implantation of metal oxide particles onto molybdenum wire surfaces through a sol-calcination process, to form a biomimetic sawblade with a high density of micro/nano saw teeth, where the acidification is essential in terms of generating active anchoring sites on the wire. When used as a sawblade in conjunction with reciprocating action to cut the viscoelastic gel, both the cut-in force and cut-in displacement could be decreased substantially. The cutting speed and frequency of reciprocating action are important operating parameters influencing cut-in force.

  20. Photoluminescence from silicon nano-particles synthesized by laser-induced decomposition of silane

    NASA Astrophysics Data System (ADS)

    Botti, S.; Coppola, R.; Gourbilleau, F.; Rizk, R.

    2000-09-01

    This work deals with photoluminescence study of silicon nanoparticles produced by CO2-laser-induced decomposition of SiH4 mixed to helium in a controlled atmosphere reactor. By adjusting the pressure of both reactor and precursor gas and its dilution rate in helium, we were able to control, to a certain extent, the silicon growth rate and hence the particle diameter. This latter was determined by both small angle neutron scattering techniques and high resolution transmission electron microscopy observations. Particles with mean diameter ranging between 3 and 10 nm were submitted to photoluminescence and infrared absorption spectroscopy measurements. The photoluminescence spectra revealed two main peaks at about 1.7 and 2.1 eV. The peak position of the former was insensitive to the change of particle size, while its intensity increased after oxidation. The latter showed, however, a slight size dependence but had undergone a drastic decrease after oxidation. These features enabled us to ascribe the red peak (1.7 eV) to some radiative surface defect, while the yellow peak (2.1 eV) appeared consistent with an emission from an oxygen-related defect such as the nonbridging oxygen hole center.

  1. Filtration of nano-particles by a gas-solid fluidized bed.

    PubMed

    Liu, Kuang-Yu; Wey, Ming-Yen

    2007-08-17

    The filtration of 80 nm SiO2 and Al(2)O(3) particles in a gas stream using fluidized beds was studied. Silica sand and activated carbon (A.C.) were adopted as bed materials to filtrate 80 nm SiO2 and Al(2)O(3) particles. The collected particles were elutriated from the fluidized bed, so the filtration was a dynamic process and the variations of the removal efficiency with time were studied. Experimental results showed that the filtrations of 80 nm SiO2 and Al(2)O(3) particles with a bed material of silica sand were not dynamic processes but the filtration by A.C. was. The removal efficiencies for SiO2 and Al(2)O(3) particles using silica sand as bed material were held steady and found to be equal, between 86 and 93%. A.C. is considered to be more efficient than silica sand because it has a high specific surface area. However, the experimental data yield conflicting results. The removal efficiency of Al(2)O(3) particles fell from 92% initially to 80% at the end of test-a little lower than that obtained by filtration using silica sand. A higher voidage of A.C. than silica sand weakens the removal of nanoparticles since the diffusion mechanism dominates. The removal efficiency of SiO2 by A.C. decayed from 83 to 40% with time passed. The huge differences between the filtration efficiency of SiO2 and that of Al(2)O(3) particles by A.C. was associated with the extensive segregation of SiO2 and A.C. particles, which caused more SiO2 particles to move to the top of the bed, where they were elutriated. The weak inter-particle force for SiO2 decreased the removal efficiency also.

  2. Effective removal of Ni(II) from aqueous solutions by modification of nano particles of clinoptilolite with dimethylglyoxime.

    PubMed

    Nezamzadeh-Ejhieh, Alireza; Kabiri-Samani, Mehdi

    2013-09-15

    In this work an Iranian natural clinoptilolite tuff was pre-treated and changed to the micro (MCP) and nano (NCP) particles by mechanical method. Modification of micro and nano particles and also their Ni-exchanged forms were done by dimethylglyoxime (DMG). The raw and modified samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG and energy dispersive analysis X-ray spectroscopy (EDAX). Removal of Ni(II) by modified and unmodified samples was investigated in batch procedure. It was found that NCP-DMG has higher capacity for removal of Ni(II). The effects of analytical parameters such as pH, dose of DMG, concentration of nickel solution, contact time and selectivity were studied and the optimal operation parameters were found as follows: pHPZC: 7.6, CNi(II): 0.01 M, contact time: 360 min and DMG dosage: 5mM. The results of selectivity experiments showed that the modified zeolite has a good selectivity for nickel in the presence of different multivalent cations. Langmuir and Freundlich isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni(II) ions could be best modelled by Langmuir equation, that indicate the monolayer sorption of Ni(II). Comparison of two kinetic models indicates that the adsorption kinetic can be well described by the pseudo-second-order rate equation that indicates that the rate limiting step for the process involves chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneously process. The negative ΔS indicates that the adsorption of nickel cations from solution occurs with lower amount ion replacement, thus chemisorptions due to complex formation are dominant process in nickel removal.

  3. Dispensing of high concentration Ag nano-particles ink for ultra-low resistivity paper-based writing electronics

    PubMed Central

    Wang, Fuliang; Mao, Peng; He, Hu

    2016-01-01

    Paper-based writing electronics has received a lot of interest recently due to its potential applications in flexible electronics. To obtain ultra-low resistivity paper-based writing electronics, we developed a kind of ink with high concentration of Ag Nano-particles (up to 80 wt%), as well as a related dispensing writing system consisting an air compressor machine and a dispenser. Additionally, we also demonstrated the writability and practical application of our proposed ink and writing system. Based on the study on the effect of sintering time and pressure, we found the optimal sintering time and pressure to obtain high quality Ag NPs wires. The electrical conductivity of nano-silver paper-based electronics has been tested using the calculated resistivity. After hot-pressure sintering at 120 °C, 25 MPa pressure for 20 minutes, the resistivity of silver NPs conductive tracks was 3.92 × 10−8 (Ωm), only 2.45 times of bulk silver. The mechanical flexibility of nano-silver paper-based electronics also has been tested. After 1000 bending cycles, the resistivity slightly increased from the initial 4.01 × 10−8 to 5.08 × 10−8 (Ωm). With this proposed ink preparation and writing system, a kind of paper-based writing electronics with ultra-low resistivity and good mechanical flexibility was achieved. PMID:26883558

  4. Electrical conductivity modification using silver nano particles of Jatropha Multifida L. and Pterocarpus Indicus w. extracts films

    NASA Astrophysics Data System (ADS)

    Diantoro, Markus; Hidayati, Nisfi Nahari Sani; Latifah, Rodatul; Fuad, Abdulloh; Nasikhudin, Sujito, Hidayat, Arif

    2016-03-01

    Natural polymers can be extracted from leaf or stem of plants. Pterocarpus Indicus W. (PIW) and Jatropha Multifida L. (JIL) plants are good candidate as natural polymer sources. PIW and JIW polymers contain chemical compound so-called flavonoids which has C6-C3-C6 carbons conjugated configuration. The renewable type of polymer as well as their abundancy of flavonoid provide us to explore their physical properties. A number of research have been reported related to broad synthesis method and mechanical properties. So far there is no specific report of electrical conductivity associated to PIW and JIL natural polymers. In order to obtain electrical conductivity and its crystallinity of the extracted polymer films, it was induced on them a various fraction of silver nano particles. The film has been prepared by means of spin coating method on nickel substrate. It was revealed that FTIR spectra confirm the existing of rutine flavonoid. The crystallinity of the samples increase from 0.66%, to 4.11% associated to the respective various of silver fractions of 0.1 M to 0.5 M. SEM images show that there are some grains of silver in the film. The nature of electric conductivity increases a long with the addition of silver. The electrical conductivity increase significantly from 3.22 S/cm, to 542.85 S/cm. On the other hand, PIW films also shows similar trends that increase of Ag induce the increase its crystallinity as well as its electrical conductivity at semiconducting level. This result opens a prospective research and application of the green renewable polymer as optoelectronic materials.

  5. MO-FG-204-06: A New Algorithm for Gold Nano-Particle Concentration Identification in Dual Energy CT

    SciTech Connect

    Chen, L; Shen, C; Ng, M; Zeng, T; Lou, Y; Jia, X

    2015-06-15

    Purpose: Gold nano-particle (GNP) has recently attracted a lot of attentions due to its potential as an imaging contrast agent and radiotherapy sensitiser. Imaging the GNP at its low contraction is a challenging problem. We propose a new algorithm to improve the identification of GNP based on dual energy CT (DECT). Methods: We consider three base materials: water, bone, and gold. Determining three density images from two images in DECT is an under-determined problem. We propose to solve this problem by exploring image domain sparsity via an optimization approach. The objective function contains four terms. A data-fidelity term ensures the fidelity between the identified material densities and the DECT images, while the other three terms enforces the sparsity in the gradient domain of the three images corresponding to the density of the base materials by using total variation (TV) regularization. A primal-dual algorithm is applied to solve the proposed optimization problem. We have performed simulation studies to test this model. Results: Our digital phantom in the tests contains water, bone regions and gold inserts of different sizes and densities. The gold inserts contain mixed material consisting of water with 1g/cm3 and gold at a certain density. At a low gold density of 0.0008 g/cm3, the insert is hardly visible in DECT images, especially for those with small sizes. Our algorithm is able to decompose the DECT into three density images. Those gold inserts at a low density can be clearly visualized in the density image. Conclusion: We have developed a new algorithm to decompose DECT images into three different material density images, in particular, to retrieve density of gold. Numerical studies showed promising results.

  6. High stable suspension of magnetite nanoparticles in ethanol by using sono-synthesized nanomagnetite in polyol medium

    SciTech Connect

    Bastami, Tahereh Rohani; Entezari, Mohammad H.

    2013-09-01

    Graphical abstract: - Highlights: • The sonochemical synthesis of magnetite nanoparticles was carried out in EG without any surfactant. • The nanoparticles with sizes ∼24 nm were composed of small building blocks with sizes ∼2 nm. • The hydrophilic magnetite nanoparticles were stable in ethanol even after 8 months. • Ultrasonic intensity showed a crucial role on the obtained high stable magnetite nanoparticles in ethanol. - Abstract: The sonochemical synthesis of magnetite nanoparticles was carried out at relatively low temperature (80 °C) in ethylene glycol (EG) as a polyol solvent. The particle size was determined by transmission electron microscopy (TEM). The magnetite nanoparticles with an average size of 24 nm were composed of small building blocks with an average size of 2–3 nm and the particles exhibited nearly spherical shape. The surface characterization was investigated by using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The stability of magnetite nanoparticles was studied in ethanol as a polar solvent. The nanoparticles showed an enhanced stability in ethanol which is due to the hydrophilic surface of the particles. The colloidal stability of magnetite nanoparticles in ethanol was monitored by UV–visible spectrophotometer. According to the results, the nanoparticles synthesized in 30 min of sonication with intensity of 35 W/cm{sup 2} (50%) led to a maximum stability in ethanol as a polar solvent with respect to the other applied intensities. The obtained magnetite nanoparticles were stable for more than12 months.

  7. Experimental stress remagnetization of magnetite

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham J.

    1996-09-01

    Pseudo-single-domain (PSD) and multidomain (MD) magnetite grains remagnetize in weak magnetic field (30 μT) during experimental triaxial deformation. The magnetite is supported in a calcite-cement matrix. Minor remagnetization occurs with hydrostatic stress of 100 MPa. Significant remagnetization requires hydrostatic pressure of 150 MPa with differential stress of ≥5 MPa superposed on the sample. Intergranular differential stresses must be much higher due to amplification at grain asperities. Stress remagnetization does not need chemical or thermal energy. New components of magnetic remanence are added parallel to the remagnetizing field. However, this only happens in grains or parts of grains with coercivities of remanence < 15 and > 60 mT. Grains with coercivities of 20-55 mT remember the primary magnetization and are not stress magnetized. These coercivity limits do not depend on the differential stress or strain rate of the experiment. The spatial distribution of vector components of remanence was isolated by AF demagnetization. After deforming a magnetized sample, the components of remanence spread along a partial great circle between the initial remanence and the direction of the remagnetizing field. The directions of the original magnetization and the remagnetizing field are the only factors controlling the course of the remagnetization path. Triaxial deformation shortened these samples by < 17%. Thus, grain rotation fails to explain the changes in directions of magnetism. The remagnetization is attributed to the low field during stress deflection of domain walls that were possibly locked in place by deformation features. If the experimental results are transferable to nature, it is possible that a pulse of excess crustal stress > 25 MPa could partially remagnetize low-dislocation-density magnetite. The experiments show that the directions of the remagnetizing field and the primary magnetization are the only variables that affect the demagnetization

  8. Magnetic and Structural Properties of Magnetite in Radular Teeth of Chiton Acanthochiton Rubrolinestus

    NASA Astrophysics Data System (ADS)

    Han, Y. N.; Liu, C. L.; Yao, L. D.; Wang, Y.; Han, X. F.

    2008-03-01

    The major radular lateral teeth of Polyplacophora Chiton comprise a magnetite biomineral cap.We have investigated the structure and magnetic properties of the biomineralized magnetite crystallites in mature teeth of Chiton Acanthochiton Rubrolinestus. From the measurement of magnetic properties of tooth particles using SQUID magnetometry we find that the saturation magnetization and the Verwey transition temperature (Tv) are 78.4 emu/g and 105 K, respectively. An in situ examination of the structure of magnetite-bearing region within individual tooth using the high resolution TEM, together with electron diffraction (ED) pattern and energy-dispersive X-ray (EDX) analyses indicates magnetite microcrystal form electron-dense polycrystalline sheets with typical length 800 nm and width 150 nm or so. These polycrystalline sheets are arranged regularly along the longitude direction of the tooth cutting surface. Furthermore, the microcrystallites in polycrystalline sheet take on the generally good crystallinity.

  9. Mechanical properties of natural chitosan/hydroxyapatite/magnetite nanocomposites for tissue engineering applications.

    PubMed

    Heidari, Fatemeh; Razavi, Mehdi; E Bahrololoom, Mohammad; Bazargan-Lari, Reza; Vashaee, Daryoosh; Kotturi, Hari; Tayebi, Lobat

    2016-08-01

    Chitosan (CS), hydroxyapatite (HA), and magnetite (Fe3O4) have been broadly employed for bone treatment applications. Having a hybrid biomaterial composed of the aforementioned constituents not only accumulates the useful characteristics of each component, but also provides outstanding composite properties. In the present research, mechanical properties of pure CS, CS/HA, CS/HA/magnetite, and CS/magnetite were evaluated by the measurements of bending strength, elastic modulus, compressive strength and hardness values. Moreover, the morphology of the bending fracture surfaces were characterized using a scanning electron microscope (SEM) and an image analyzer. Studies were also conducted to examine the biological response of the human Mesenchymal Stem Cells (hMSCs) on different composites. We conclude that, although all of these composites possess in-vitro biocompatibility, adding hydroxyapatite and magnetite to the chitosan matrix can noticeably enhance the mechanical properties of the pure chitosan.

  10. Controllable in situ synthesis of magnetite coated silica-core water-dispersible hybrid nanomaterials.

    PubMed

    Qu, Haiou; Tong, Sheng; Song, Kejing; Ma, Hui; Bao, Gang; Pincus, Seth; Zhou, Weilie; O'Connor, Charles

    2013-08-20

    Magnetite nanoparticle coated silica (Fe3O4@SiO2) hybrid nanomaterials hold an important position in the fields of cell imaging and drug delivery. Here we report a large scale synthetic procedure that allows attachment of magnetite nanoparticles onto a silica surface in situ. Many different silica nanomaterials such as Stöber silica nanospheres, mesoporous silica nanoparticles, and hollow silica nanotubes have been coated with a high density layer of water-dispersible magnetite nanoparticles. The size and attachment efficiency of the magnetite nanoparticle can be well tuned by adjusting the precursor concentration and reflux time. The functionalization of Fe3O4@SiO2 nanoparticles with dye molecules and biocompatible polymers impart optical imaging modality and good colloidal stability in either buffer solution or serum. The functionalized materials also exhibited strong potential as negative contrast agents in T2 weighted magnetic resonance imaging.

  11. Use of different rapid mixing devices for controlling the properties of magnetite nanoparticles produced by precipitation

    NASA Astrophysics Data System (ADS)

    Wei, Li; Hervé, Muhr; Edouard, Plasari

    2012-03-01

    Magnetite nanoparticles were precipitated by the classic Massart's method in a 2.5 L stirred tank reactor where the injection of reagent solutions was effectuated by different micro-mixers (T-tube and Hartridge-Roughton rapid mixing devices). The specific surface area, the average particle size and the particle size distribution were highly influenced by changing operating parameters. Laser Diffraction, BET adsorption, Energy-Dispersive X-ray Spectroscopy (EDX), Raman spectroscopy and Transmission Electron Microscopy (TEM) were used for characterizing magnetite nanoparticles. Especially, Hartridge-Roughton micromixer appears to be the most efficient mixing device for producing magnetite nanoparticles. The average particle size of magnetite nanoparticles prepared by Hartridge-Roughton rapid mixing device was less than 10 nm and the EDX and Raman spectroscopy shows that the particle purity is quite high.

  12. Evidence for exclusively inorganic formation of magnetite in Martian meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Brearley, A. J.; Lauer, H. V., Jr.; Treiman, A. H.; Zolensky, M. E.; Schwandt, C. S.; Lofgren, G. E.

    2004-01-01

    globules in Martian meteorite ALH84001 is replicated by an inorganic process; and (2) the most common crystal morphology for biogenic (MV-1) magnetite is distinctly different from that in both ALH84001 and our inorganic laboratory products. Therefore, [111]-elongated magnetite crystals in ALH84001 do not constitute, as previously claimed, a robust biosignature and, in fact, an exclusively inorganic origin for the magnetite is fully consistent with our results. Furthermore, the inorganic synthesis method, i.e., the thermal decomposition of hydrothermally precipitated Fe-rich carbonate, is a process analogue for formation of the magnetite on Mars. Namely, precipitation of carbonate globules from carbonate-rich hydrothermal solutions followed at some later time by a thermal pulse, perhaps in association with meteoritic impact or volcanic processes on the Martian surface.

  13. Magnetite and magnetite/silver core/shell nanoparticles with diluted magnet-like behavior

    SciTech Connect

    Garza-Navarro, Marco; Gonzalez, Virgilio; Ortiz, Ubaldo; De la Rosa, Elder

    2010-01-15

    In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems. - Graphical abstract: Biopolymer chitosan was used as stabilization media to synthesize both magnetite and magnetite/silver core/shell nanoparticles. Results of HRTEM and NBD patterns confirm core/shell morphology of the obtained nanoparticles. It was found that the composites show diluted magnet-like behavior.

  14. Effects of pH and anions on the sorption of selenium ions onto magnetite.

    PubMed

    Kim, Seung Soo; Min, Je Ho; Lee, Jae Kwang; Baik, Min Hoon; Choi, Jong-Won; Shin, Hyung Seon

    2012-02-01

    This study analyzes the influence of carbonate and silicate, which are generally abundant in granitic groundwater, on the sorption of selenium ions onto magnetite in order to understand the behaviors of selenium in a radioactive waste repository. Selenite was sorbed onto magnetite very well below pH 10, but silicate and carbonate hindered the sorption of selenite onto magnetite. On the other hand, little selenate was sorbed onto magnetite in neutral and weak alkaline solutions of 0.02 M NaNO(3) or NaClO(4), matching the ionic strength in a granitic groundwater, even though silicate or carbonate was not contained in the solutions. The surface complexation constants between selenite and magnetite were obtained by using a geochemical program, FITEQL 4.0, from the experimental data, and the formation of an inner-sphere surface complex such as =FeOSeO(2)(-) was suggested for the sorption of selenite onto magnetite from the diffuse double layer model calculation.

  15. Acceleration of microwave-assisted enzymatic digestion reactions by magnetite beads.

    PubMed

    Chen, Wei-Yu; Chen, Yu-Chie

    2007-03-15

    In this study, we demonstrated that microwave-assisted enzymatic digestion could be greatly accelerated by multifunctional magnetite beads. The acceleration of microwave-assisted enzymatic digestion by the presence of the magnetite beads was attributable to several features of the beads. Their capacity to absorb microwave radiation leads to rapid heating of the beads. Furthermore, their negatively charged functionalities cause adsorption of proteins with opposite charges onto their surfaces by electrostatic interactions, leading to a concentration on the surfaces of the beads of proteins present in trace amounts in the solution. The adsorbed proteins are denatured and hence rendered vulnerable to enzymatic digestion and are digested on the beads. For microwave heating, 30 s was sufficient for carrying out the tryptic digestion of cytochrome c, in the presence of magnetite beads, while 1 min was adequate for tryptic digestion of myoglobin. The digestion products were characterized by MALDI-MS. This rapid enzymatic digestion allowed the entire time for identification of proteins to be greatly reduced. Furthermore, specific proteins present in trace quantities were enriched from the sample on the magnetite beads and could be rapidly isolated from the sample by employing an external magnetic field. These multiple roles of magnetite beads, as the absorber for microwave irradiation, the concentrating probe, and the agent for unfolding proteins, contributed to their capability of accelerating microwave-assisted enzymatic digestion. We also demonstrated that trypsin immobilized magnetite beads were suitable for use in microwave-assisted enzymatic digestion.

  16. Magnetite nanoparticles-chitosan composite containing carbon paste electrode for glucose biosensor application.

    PubMed

    Kavitha, A L; Prabu, H Gurumallesh; Babu, S Ananda; Suja, S K

    2013-01-01

    This work was aimed to develop reusable magnetite chitosan composite containing carbon paste electrode for biosensor application. Glucose oxidase (GOx) enzyme was used to prepare GOx-magnetite-chitosan nanocomposite containing carbon paste electrode for sensitive detection of glucose. The immobilized enzyme retained its bioactivity, exhibited a surface confined reversible electron transfer reaction, and had good stability. The surface parameters like surface coverage (tau), Diffusion coefficient (D0), and rate constant (kS) were studied. The carbon paste modified electrode virtually eliminated the interference during the detection of glucose. The excellent performance of the biosensor is attributed to large surface-to-volume ratio, high conductivity and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes electron transfer between redox enzymes and the surface of electrode. The shelf life of the developed electrode system is about 12 weeks under refrigerated conditions. We report for the first time in the fabrication of carbon paste bioelectrode containing magnetite-chitosan-GOx.

  17. Fe{sup II} induced mineralogical transformations of ferric oxyhydroxides into magnetite of variable stoichiometry and morphology

    SciTech Connect

    Usman, M.; Abdelmoula, M.; Hanna, K.; and others

    2012-10-15

    The Moessbauer spectroscopy was used to monitor the mineralogical transformations of ferrihydrite (F), lepidocrocite (L) and goethite (G) into magnetite as a function of aging time. Ferric oxyhydroxides were reacted with soluble Fe{sup II} and OH{sup -} in stoichiometric amounts to form magnetite at an initial pH of {approx}9.7. Observed transformation extent into magnetite followed the order: F>L>G with almost 30% of untransformed G after 1 month. The departure from stoichiometry, {delta}, of magnetite (Fe{sub 3-{delta}}O{sub 4}) generated from F ({delta}{approx}0.04) and L ({delta}{approx}0.05) was relatively low as compared to that in magnetite from G ({delta}{approx}0.08). The analysis by transmission electron microscopy and BET revealed that generated magnetite was also different in terms of morphology, particle size and surface area depending on the nature of initial ferric oxyhydroxide. This method of preparation is a possible way to form nano-sized magnetite. - Graphical abstract: Moessbauer spectrum of the early stage of magnetite formation formed from the interaction of adsorbed Fe{sup II} species with goethite. Highlights: Black-Right-Pointing-Pointer Ferric oxides were reacted with hydroxylated Fe{sup II} to form magnetite. Black-Right-Pointing-Pointer Magnetite formation was quantified as a function of aging time. Black-Right-Pointing-Pointer Complete transformation of ferrihydrite and lepidocrocite was achieved. Black-Right-Pointing-Pointer Almost 70% of initial goethite was transformed. Black-Right-Pointing-Pointer Resulting magnetites have differences in stoichiometry and morphological properties.

  18. Investigation of heteroepitaxial growth of magnetite thin films.

    SciTech Connect

    Sterbinsky, G. E.; Cheng, J.; Chiu, P. T.; Wessels, B. W.; Keavney, D. J.; X-Ray Science Division; Northwestern Univ.

    2007-07-01

    Epitaxial magnetite (Fe{sub 3}O{sub 4}) thin films were deposited by molecular beam epitaxy using molecular oxygen as the oxidant. Films deposited on (001) SrTiO{sub 3}, (001) MgO, and (001) BaTiO{sub 3} surfaces are epitaxial with the film (001) parallel to the substrate (001) and the film <100> parallel to the substrate <100>. X-ray magnetic circular dichroism was used to determine the relative Fe{sup 2+}/Fe{sup 3+} stoichiometry of the magnetite films, which was nearly independent of oxygen partial pressure over the range studied. All films show no in-plane magnetic anisotropy. Coercive fields ranged from 0.019 to 0.039 T and depended on film roughness.

  19. Preparation of magnetite-fullerene nanocomposite with enzyme immobilization.

    PubMed

    Kalska-Szostko, B; Rogowska, M

    2012-09-01

    This study presents modification of magnetite nanoparticles and fullerene for biocompatibility. It show also specific fabrication of magnetite-carbon nanocomposite with immobilized biomolecule. The composites were created by joining individual components step-by-step manner (fullerene to magnetite and glucose oxidase or glucose oxidase to magnetite and fullerene). The resulting nanocomposites were characterized by infrared spectroscopy (IR) and transmission electron microscopy (TEM).

  20. Effect of silver nano-particles on soil microbial growth, activity and community diversity in a sandy loam soil.

    PubMed

    Samarajeewa, A D; Velicogna, J R; Princz, J I; Subasinghe, R M; Scroggins, R P; Beaudette, L A

    2017-01-01

    Silver nano-particles (AgNPs) are widely used in a range of consumer products as a result of their antimicrobial properties. Given the broad spectrum of uses, AgNPs have the potential for being released to the environment. As a result, environmental risks associated with AgNPs need to be assessed to aid in the development of regulatory guidelines. Research was performed to assess the effects of AgNPs on soil microbial activity and diversity in a sandy loam soil with an emphasis on using a battery of microbial tests involving multiple endpoints. The test soil was spiked with PVP coated (0.3%) AgNPs at the following concentrations of 49, 124, 287, 723 and 1815 mg Ag kg(-1) dry soil. Test controls included an un-amended soil; soil amended with PVP equivalent to the highest PVP concentration of the coated AgNP; and soil amended with humic acid, as 1.8% humic acid was used as a suspension agent for the AgNPs. The impact on soil microbial community was assessed using an array of tests including heterotrophic plate counting, microbial respiration, organic matter decomposition, soil enzyme activity, biological nitrification, community level physiological profiling (CLPP), Ion Torrent™ DNA sequencing and denaturing gradient gel electrophoresis (DGGE). An impact on microbial growth, activity and community diversity was evident from 49 to 1815 mg kg(-1) with the median inhibitory concentrations (IC50) as low as 20-31 mg kg(-1) depending on the test. AgNP showed a notable impact on microbial functional and genomic diversity. Emergence of a silver tolerant bacterium was observed at AgNP concentrations of 49-287 mg kg(-1) after 14-28 days of incubation, but not detectable at 723 and 1815 mg kg(-1). The bacterium was identified as Rhodanobacter sp. The study highlighted the effectiveness of using multiple microbial endpoints for inclusion to the environmental risk assessment of nanomaterials.

  1. Ultraviolet to near infrared response of optically sensitive nonvolatile memories based on platinum nano-particles and high-k dielectrics on a silicon on insulator substrate

    NASA Astrophysics Data System (ADS)

    Mikhelashvili, V.; Meyler, B.; Shneider, Y.; Yofis, S.; Salzman, J.; Atiya, G.; Cohen-Hyams, T.; Ankonina, G.; Kaplan, W. D.; Lisiansky, M.; Roizin, Y.; Eisenstein, G.

    2013-02-01

    An optically triggered nonvolatile memory based on platinum nano-particles embedded within a SiO2 and HfO2 dielectric stack on a silicon on insulator (SOI) substrate is presented. The memory cell exhibits a very wide spectral response, from 220 nm to 950 nm; much wider than common photo-detectors fabricated on SOI. It offers several functionalities including a low programming voltage and wide hysteresis of the capacitance-voltage characteristics, an illumination and voltage sweep amplitude dependent hysteresis of the current-voltage characteristics, and plasmonic enhanced, efficient broad-band photo detection.

  2. A reductive dissolution study of magnetite

    SciTech Connect

    Hui-Jun Won; Jung-Soon Park; Chong-Hun Jung; Sang-Yoon Park; Wang-Kyu Choi; Jei-Kwon Moon

    2013-07-01

    Magnetite dissolution tests using a hydrazine base solution were performed at a temperature range of 90 to 150 deg. C. The dissolution rate of magnetite increased with [N{sub 2}H{sub 4}], time, and temperature. The optimum solution pH in the experimental range was 3. The addition of copper ion to the hydrazine base solution greatly increased the magnetite dissolution rate. This was explained by the complex formation between N{sub 2}H{sub 4} and Cu ions, and the reducing power of the hydrazine-Cu complex to the ferric ions of magnetite. The reductive decontamination solution can be applied below 100 deg. C by the addition of copper ions. The chemical decontamination of a Type 304 stainless steel specimen using a hydrazine base reductive decontamination solution was also performed. The contact dose rate was greatly decreased by the repetitive application of NP and the hydrazine base solution. (authors)

  3. Quantum dot capped magnetite nanorings as high performance nanoprobe for multiphoton fluorescence and magnetic resonance imaging.

    PubMed

    Fan, Hai-Ming; Olivo, Malini; Shuter, Borys; Yi, Jia-Bao; Bhuvaneswari, Ramaswamy; Tan, Hui-Ru; Xing, Gui-Chuan; Ng, Cheng-Teng; Liu, Lei; Lucky, Sasidharan S; Bay, Boon-Huat; Ding, Jun

    2010-10-27

    In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications.

  4. Magnetic and structural properties of magnetite in radular teeth of chiton Acanthochiton rubrolinestus.

    PubMed

    Han, Yunan; Liu, Chuanlin; Zhou, Dong; Li, Fashen; Wang, Yong; Han, Xiufeng

    2011-04-01

    The teeth of the Polyplacophora Chiton Acanthochiton Rubrolinestus contain biomineralized magnetite crystallites whose biological functions in relation to structure and magnetic properties are not well understood. Here, using superconducting quantum interference device (SQUID) magnetometry, we find that the saturation magnetization (σ(s)) and the Verwey transition temperature (T(v)) of tooth particles are 78.4 emu/g and 105 K, respectively. These values are below those of the stoichiometric magnetite. An in situ examination of the structure of the magnetite-bearing region within an individual tooth using high-resolution transmission electron microscopy indicates magnetite microcrystals form electron dense polycrystalline sheets with typical lengths of about 800 nm and widths of about 150 nm. These polycrystalline sheets are arranged regularly along the longitudinal direction of the tooth cutting surface. In addition, the crystallites in polycrystalline sheets take on generally good crystallinity. The magnetic microstructures of in situ magnetic force microscopy demonstrate that the [111] easy direction of magnetite microcrystals are aligned along the length of the tooth, whereas the [111] direction is parallel to the thickness of the tooth. Both Mössbauer spectra and magnetization versus temperature measurements under field cooled and zero-field cooled conditions do not detect superparamagnetic magnetite crystallites in the mature major lateral tooth particles of this chiton.

  5. Lanthanide sorbent based on magnetite nanoparticles functionalized with organophosphorus extractants

    PubMed Central

    Basualto, Carlos; Gaete, José; Molina, Lorena; Valenzuela, Fernando; Yañez, Claudia; Marco, Jose F

    2015-01-01

    In this work, an adsorbent was prepared based on the attachment of organophosphorus acid extractants, namely, D2EHPA, CYANEX 272, and CYANEX 301, to the surface of superparamagnetic magnetite (Fe3O4) nanoparticles. The synthesized nanoparticles were coated with oleic acid, first by a chemisorption mechanism and later by the respective extractant via physical adsorption. The obtained core–shell functionalized magnetite nanoparticle composites were characterized by dynamic light scattering, scanning electron microscopy, transmission electron microscopy, thermogravimetry, infrared absorption and vibrating sample magnetometry. All the prepared nanoparticles exhibited a high saturation magnetization capacity that varied between 72 and 46 emu g−1 and decreased as the magnetite nanoparticle was coated with oleic acid and functionalized. The scope of this study also included adsorption tests for lanthanum, cerium, praseodymium, and neodymium and the corresponding analysis of their results. Sorption tests indicated that the functionalized nanoparticles were able to extract the four studied lanthanide metal ions, although the best extraction performance was observed when the sorbent was functionalized with CYANEX 272, which resulted in a loading capacity of approximately 12–14 mgLa/gMNP. The magnetization of the synthesized nanoparticles was verified during the separation of the lanthanide-loaded sorbent from the raffinate by using a conventional magnet. PMID:27877811

  6. Characterization of Magnetite Scale Formed in Naphthenic Acid Corrosion

    NASA Astrophysics Data System (ADS)

    Jin, Peng; Robbins, Winston; Bota, Gheorghe; Nesic, Srdjan

    2017-02-01

    Naphthenic acid corrosion (NAC) is one of the major concerns for corrosion engineers in refineries. Traditionally, the iron sulfide (FeS) scale, formed when sulfur compounds in crudes corrode the metal, is expected to be protective and limit the NAC. Nevertheless, no relationship has been found between protectiveness and the characteristics of FeS scale. In this study, lab scale tests with model sulfur compounds and naphthenic acids replicated corrosive processes of refineries with real crude fractions behavior. The morphology and chemical composition of scales were analyzed with scanning electron microscopy and transmission electron microscopy. These high-resolution microscopy techniques revealed the presence of an iron oxide (Fe3O4 or magnetite) scale and discrete particulates on metal surfaces under FeS scales, especially on a low chrome steel. The presence of the iron oxide was correlated with the naphthenic acid activity during the experiments. It is postulated that the formation of the magnetite scale resulted from the decomposition of iron naphthenates at high temperatures. It is further postulated that a nano-particulate form of magnetite may be providing corrosion resistance.

  7. Characterization of Magnetite Scale Formed in Naphthenic Acid Corrosion

    NASA Astrophysics Data System (ADS)

    Jin, Peng; Robbins, Winston; Bota, Gheorghe; Nesic, Srdjan

    2016-10-01

    Naphthenic acid corrosion (NAC) is one of the major concerns for corrosion engineers in refineries. Traditionally, the iron sulfide (FeS) scale, formed when sulfur compounds in crudes corrode the metal, is expected to be protective and limit the NAC. Nevertheless, no relationship has been found between protectiveness and the characteristics of FeS scale. In this study, lab scale tests with model sulfur compounds and naphthenic acids replicated corrosive processes of refineries with real crude fractions behavior. The morphology and chemical composition of scales were analyzed with scanning electron microscopy and transmission electron microscopy. These high-resolution microscopy techniques revealed the presence of an iron oxide (Fe3O4 or magnetite) scale and discrete particulates on metal surfaces under FeS scales, especially on a low chrome steel. The presence of the iron oxide was correlated with the naphthenic acid activity during the experiments. It is postulated that the formation of the magnetite scale resulted from the decomposition of iron naphthenates at high temperatures. It is further postulated that a nano-particulate form of magnetite may be providing corrosion resistance.

  8. Fluctuation induced conductivity studies in YBa2Cu3Oy compound embedded by superconducting nano-particles Y-deficient YBa2Cu3Oy: effect of silver inclusion

    NASA Astrophysics Data System (ADS)

    Hannachi, E.; Slimani, Y.; Ben Salem, M. K.; Hamrita, A.; Al-Otaibi, A. L.; Almessiere, M. A.; Ben Salem, M.; Ben Azzouz, F.

    2016-09-01

    The effect of superconducting Y-deficient YBa2Cu3Oy nano-particles prepared by the planetary ball milling technique and silver inclusion on electrical fluctuation conductivity of polycrystalline YBa2Cu3Oy has been reported. Samples, synthesized by the conventional solid-state reaction technique, have been investigated using X-ray diffraction, scanning electron microscope and electrical resistivity. Scanning electron microscope analyses show that nano-particles of Y-deficient YBa2Cu3Oy are embedded in the superconducting matrix. The density of these nano-particles strongly depends on milling parameters. The fluctuation conductivity has been analyzed as a function of reduced temperature using the Aslamazov-Larkin model. Three different fluctuation regions namely critical, mean-field and short-wave are observed. The zero-temperature coherence length, the effective layer thickness of the two-dimensional system, critical magnetic fields and critical current density are estimated. Superconducting parameters are affected by Y-deficient YBa2Cu3Oy nano-particles. It has been found that attainment of an optimum concentration and well-dispersed of nano-sized inclusions by ball milling process improves the physical properties. On the other hand, the sample with Y-deficient YBa2Cu3Oy nano-particles and Ag exhibits better superconducting properties in comparison with free added one.

  9. Comparison of flux motion in type-II superconductors including pinning centers with the shapes of nano-rods and nano-particles by using 3D-TDGL simulation

    NASA Astrophysics Data System (ADS)

    Ito, Shintaro; Ichino, Yusuke; Yoshida, Yutaka

    2015-11-01

    Time-dependent Ginzburg-Landau (TDGL) equations are very useful method for simulation of the motion of flux quanta in type-II superconductors. We constructed the 3D-TDGL simulator and succeeded to simulate the motion of flux quanta in 3-dimension. We carried out the 3D-TDGL simulation to compare two superconductors which included only pinning centers with the shape of nano-rods and only nano-particle-like pinning centers in the viewpoint of the flux motion. As a result, a motion of "single-kink" caused the whole motion of a flux quantum in the superconductor including only the nano-rods. On the other hand, in the superconductor including the nano-particles, the flux quanta were pinned by the nano-particles in the various magnetic field applied angles. As the result, no "single-kink" occurred in the superconductor including the nano-particles. Therefore, the nano-particle-like pinning centers are effective shape to trap flux quanta for various magnetic field applied angles.

  10. Effect of concentration of sodium silicate solution in the synthesis of silica-coated magnetite nanoparticles by ultrasonication

    NASA Astrophysics Data System (ADS)

    Fajaroh, Fauziatul; Sumari, Nazriati

    2016-02-01

    An ex-situ silica coating of magnetite nanoparticles synthesized electrochemically had been successfully carried out by ultrasonication. An aqueous solution of sodium silicate had been used as silica source.The Si-O-Si, Si-O and Fe-O-Si bonds on the surface of the silica-coated magnetite had been successfully identified using FTIR. Reduction in particle size due to the influence of ultrasound was studied using SEM. Enhancement in the specific surface area of the particles due to the silica coating and reduction in particle size was learned through BET analysis. The Characters of the resulting silica-coated magnetite were influenced by the concentration of sodium silicate solution. The greater the concentration of sodium silicate solution, the smaller the particle crystallinity and the larger the particles surface area was produced. The resulting silica-coated magnetite has a surface area of 38.171 to 67.993 m2/g, otherwise the non-coated particles only has a surface area of 27.894 m2/g. This silica-coated magnetite nanoparticles has more potent as an adsorbent than that of the bare magnetite. Besides that, the presence of silanol groups on its surface makes an opportunity for further functionalization needed for some applications.

  11. Submicron magnetite grains and carbon compounds in Martian meteorite ALH84001: inorganic, abiotic formation by shock and thermal metamorphism.

    PubMed

    Treiman, Allan H

    2003-01-01

    Purported biogenic features of the ALH84001 Martian meteorite (the carbonate globules, their submicron magnetite grains, and organic matter) have reasonable inorganic origins, and a comprehensive hypothesis is offered here. The carbonate globules were deposited from hydrothermal water, without biological mediation. Thereafter, ALH84001 was affected by an impact shock event, which raised its temperature nearly instantaneously to 500-700K, and induced iron-rich carbonate in the globules to decompose to magnetite and other minerals. The rapidity of the temperature increase caused magnetite grains to nucleate in abundance; hence individual crystals were very small. Nucleation and growth of magnetite crystals were fastest along edges and faces of the precursor carbonate grains, forcing the magnetite grains to be platy or elongated, including the "truncated hexa-octahedra" shape. ALH84001 had formed at some depth within Mars where the lithostatic pressure was significantly above that of Mars' surface. Also, because the rock was at depth, the impact heat dissipated slowly. During this interval, magnetite crystals approached chemical equilibria with surrounding minerals and gas. Their composition, nearly pure Fe(3)O(4), reflects those of equilibria; elements that substitute into magnetite are either absent from iron-rich carbonate (e.g., Ti, Al, Cr), or partitioned into other minerals during magnetite formation (Mg, Mn). Many microstructural imperfections in the magnetite grains would have annealed out as the rock cooled. In this post-shock thermal regime, carbon-bearing gas from the decomposition of iron carbonates reacted with water in the rock (or from its surroundings) to produce organic matter via Fischer-Tropschlike reactions. Formation of such organic compounds like polycyclic aromatic hydrocarbons would have been catalyzed by the magnetite (formation of graphite, the thermochemically stable phase, would be kinetically hindered).

  12. Modeling the Break-up of Nano-particle Clusters in Aluminum- and Magnesium-Based Metal Matrix Nano-composites

    NASA Astrophysics Data System (ADS)

    Manoylov, Anton; Bojarevics, Valdis; Pericleous, Koulis

    2015-07-01

    Aluminum- and magnesium-based metal matrix nano-composites with ceramic nano-reinforcements promise low weight with high durability and superior strength, desirable properties in aerospace, automobile, and other applications. However, nano-particle agglomerations lead to adverse effects on final properties: large-size clusters no longer act as dislocation anchors, but instead become defects; the resulting particle distribution will be uneven, leading to inconsistent properties. To prevent agglomeration and to break-up clusters, ultrasonic processing is used via an immersed sonotrode, or alternatively via electromagnetic vibration. A study of the interaction forces holding the nano-particles together shows that the choice of adhesion model significantly affects estimates of break-up force and that simple Stokes drag due to stirring is insufficient to break-up the clusters. The complex interaction of flow and co-joint particles under a high frequency external field (ultrasonic, electromagnetic) is addressed in detail using a discrete-element method code to demonstrate the effect of these fields on de-agglomeration.

  13. Development of a silica monolith modified with Fe3O4 nano-particles in centrifugal spin column format for the extraction of phosphorylated compounds.

    PubMed

    Alwy, Ali; Clarke, Sarah P; Brougham, Dermot F; Twamley, Brendan; Paull, Brett; White, Blánaid; Connolly, Damian

    2015-01-01

    In this study, citrate-stabilised iron oxide nano-particles (∼16 nm) have been immobilised on commercial silica monolithic centrifugal spin columns (MonoSpin) for the extraction of phosphorylated compounds. Two alternative strategies were adopted involving either direct electrostatic attachment to an aminated MonoSpin (single-layer method) in the first instance, or the use of a layer-by-layer method with poly(diallyldimethylammonium) chloride. Field-emission scanning electron spectroscopy and energy-dispersive X-ray spectroscopy was used for confirming notably higher coverage of nano-particles using the layer-by-layer method (2.49 ± 0.53 wt%) compared with the single-layer method (0.43 ± 0.30 wt%). The modified monolith was used for the selective separation/extraction of adenosine monophosphate, adenosine diphosphate and adenosine triphosphate with elution using a phosphate buffer. A reversed-phase liquid chromatographic assay was used for confirming that adenosine, as a non-phosphorylated control was not retained on the modified MonoSpin devices, whereas recovery of 80% for adenosine monophosphate, 86% for adenosine diphosphate and 82% for adenosine triphosphate was achieved.

  14. Effects of common groundwater ions on chromate removal by magnetite: Importance of chromate adsorption

    SciTech Connect

    Meena, Amanda H.; Arai, Yuji

    2016-04-29

    Reductive precipitation of hexavalent chromium (Cr(VI)) with magnetite is a well-known Cr(VI) remediation method to improve water quality. The rapid (< a few hr) reduction of soluble Cr(VI) to insoluble Cr(III) species by Fe(II) in magnetite has been the primary focus of the Cr(VI) removal process in the past. However, the contribution of simultaneous Cr(VI) adsorption processes in aged magnetite has been largely ignored, leaving uncertainties in evaluating the application of in situ Cr remediation technologies for aqueous systems. In this study, effects of common groundwater ions (i.e., nitrate and sulfate) on Cr(VI) sorption to magnetite were investigated using batch geochemical experiments in conjunction with X-ray absorption spectroscopy. As a result, in both nitrate and sulfate electrolytes, batch sorption experiments showed that Cr(VI) sorption decreases with increasing pH from 4 to 8. In this pH range, Cr(VI) sorption decreased with increasing ionic strength of sulfate from 0.01 to 0.1 M whereas nitrate concentrations did not alter the Cr(VI) sorption behavior. This indicates the background electrolyte specific Cr(VI) sorption process in magnetite. Under the same ionic strength, Cr(VI) removal in sulfate containing solutions was greater than that in nitrate solutions. This is because the oxidation of Fe(II) by nitrate is more thermodynamically favorable than by sulfate, leaving less reduction capacity of magnetite to reduce Cr(VI) in the nitrate media. X-ray absorption spectroscopy analysis supports the macroscopic evidence that more than 75 % of total Cr on the magnetite surfaces was adsorbed Cr(VI) species after 48 h. In conclusion, this experimental geochemical study showed that the adsorption process of Cr(VI) anions was as important as the reductive precipitation of Cr(III) in describing the removal of Cr(VI) by magnetite, and these interfacial adsorption processes could be impacted by common groundwater ions like sulfate and nitrate. The results of

  15. Effects of common groundwater ions on chromate removal by magnetite: Importance of chromate adsorption

    DOE PAGES

    Meena, Amanda H.; Arai, Yuji

    2016-04-29

    Reductive precipitation of hexavalent chromium (Cr(VI)) with magnetite is a well-known Cr(VI) remediation method to improve water quality. The rapid (< a few hr) reduction of soluble Cr(VI) to insoluble Cr(III) species by Fe(II) in magnetite has been the primary focus of the Cr(VI) removal process in the past. However, the contribution of simultaneous Cr(VI) adsorption processes in aged magnetite has been largely ignored, leaving uncertainties in evaluating the application of in situ Cr remediation technologies for aqueous systems. In this study, effects of common groundwater ions (i.e., nitrate and sulfate) on Cr(VI) sorption to magnetite were investigated using batchmore » geochemical experiments in conjunction with X-ray absorption spectroscopy. As a result, in both nitrate and sulfate electrolytes, batch sorption experiments showed that Cr(VI) sorption decreases with increasing pH from 4 to 8. In this pH range, Cr(VI) sorption decreased with increasing ionic strength of sulfate from 0.01 to 0.1 M whereas nitrate concentrations did not alter the Cr(VI) sorption behavior. This indicates the background electrolyte specific Cr(VI) sorption process in magnetite. Under the same ionic strength, Cr(VI) removal in sulfate containing solutions was greater than that in nitrate solutions. This is because the oxidation of Fe(II) by nitrate is more thermodynamically favorable than by sulfate, leaving less reduction capacity of magnetite to reduce Cr(VI) in the nitrate media. X-ray absorption spectroscopy analysis supports the macroscopic evidence that more than 75 % of total Cr on the magnetite surfaces was adsorbed Cr(VI) species after 48 h. In conclusion, this experimental geochemical study showed that the adsorption process of Cr(VI) anions was as important as the reductive precipitation of Cr(III) in describing the removal of Cr(VI) by magnetite, and these interfacial adsorption processes could be impacted by common groundwater ions like sulfate and nitrate. The

  16. The chemistry of hydrothermal magnetite: a review

    USGS Publications Warehouse

    Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John

    2014-01-01

    Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of hydrothermal magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, hydrothermal magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in hydrothermal magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of hydrothermal and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United

  17. Three-Dimensional Morphological Analysis of ALH84001 Magnetite Using Electron Tomography

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, Kathie L.; Clemett, Simon J.; Shimmin, Joel; Morphew, Mary; McIntosh, J. Richard; Bazylinski, Dennis A.; Kirschvink, Joseph L.; Wentworth, Susan J.; McKay, David S.; Vali, Hojatollah

    2003-01-01

    We report here the crystal morphologies of MV-1 and ALH84001 magnetites as calculated by back-projection using electron tomography. In the present study, we used a 300 keV TEM with a field emission gun (Tecnai F-30 from FEI Inc.), equipped with a 2048 x 2048 pixel CCD camera from Gatan Inc. to image magnetite crystals over tilt ranges of approx. +/- 72 deg in 2 deg tilt intervals. The images were aligned for back-projection, either manually, or through the use of fiducial 5 nm Au spheres affixed to the specimen prior to microscopy. Three-dimensional (3-D) reconstructions were computed using weighted back-projection of the tilted views. The tomograms were viewed and analyzed as a series of slices 1.0 nm thick, taken parallel to the specimen-supporting grid, using the IMOD software package. The shape of each magnetite crystal was determined by defining the external contour of a given magnetite in each slice and assembling a stack of these contours in 3-D. To aid in visualization, the stacked contour array was reduced to an optimal mesh by Delaunay triangulation. The surface normal to each of the triangles in the mesh was calculated and the triangle faces colored according to the orientation of that surface normal relative to the principal crystallographic axis of magnetite. Green surfaces correspond to {111} orientations, blue surfaces to {100} orientations, and red surfaces to {110} orientations. Triangles whose surface normal did not correspond to one of the principal axes were colored gray. Within the experimental and numerical uncertainties of the deconvolution, the tomographic reconstruction of both MV-1 and ALH84001 magnetites are equivalent and correspond to a truncated hexa-octahedral morphology.

  18. Kinetic modeling of the formation and growth of inorganic nano-particles during pulverized coal char combustion in O2/N2 and O2/CO2 atmospheres

    SciTech Connect

    Shaddix, Christopher R.; Niu, Yanqing; Hui, Shi'en; Wang, Shuai

    2016-08-01

    In this formation of nano-particles during coal char combustion, the vaporization of inorganic components in char and the subsequent homogeneous particle nucleation, heterogeneous condensation, coagulation, and coalescence play decisive roles. Furthermore, conventional measurements cannot provide detailed information on the dynamics of nano-particle formation and evolution, In this study, a sophisticated intrinsic char kinetics model that considers ash effects (including ash film formation, ash dilution, and ash vaporization acting in tandem), both oxidation and gasification by CO2 and H2O, homogeneous particle nucleation, heterogeneous vapor condensation, coagulation, and and coalescence mechanisms is developed and used to compare the temporal evolution of the number and size of nano-particles during coal char particle combustion as a function of char particle size, ash content, and oxygen content in O2/N2 and O2/CO2 atmospheres .

  19. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens

    NASA Astrophysics Data System (ADS)

    Byrne, J. M.; Telling, N. D.; Coker, V. S.; Pattrick, R. A. D.; van der Laan, G.; Arenholz, E.; Tuna, F.; Lloyd, J. R.

    2011-11-01

    The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.

  20. Core Amino Acid Residues in the Morphology-Regulating Protein, Mms6, for Intracellular Magnetite Biomineralization

    PubMed Central

    Yamagishi, Ayana; Narumiya, Kaori; Tanaka, Masayoshi; Matsunaga, Tadashi; Arakaki, Atsushi

    2016-01-01

    Living organisms produce finely tuned biomineral architectures with the aid of biomineral-associated proteins. The functional amino acid residues in these proteins have been previously identified using in vitro and in silico experimentation in different biomineralization systems. However, the investigation in living organisms is limited owing to the difficulty in establishing appropriate genetic techniques. Mms6 protein, isolated from the surface of magnetite crystals synthesized in magnetotactic bacteria, was shown to play a key role in the regulation of crystal morphology. In this study, we have demonstrated a defect in the specific region or substituted acidic amino acid residues in the Mms6 protein for observing their effect on magnetite biomineralization in vivo. Analysis of the gene deletion mutants and transformants of Magnetospirillum magneticum AMB-1 expressing partially truncated Mms6 protein revealed that deletions in the N-terminal or C-terminal regions disrupted proper protein localization to the magnetite surface, resulting in a change in the crystal morphology. Moreover, single amino acid substitutions at Asp123, Glu124, or Glu125 in the C-terminal region of Mms6 clearly indicated that these amino acid residues had a direct impact on magnetite crystal morphology. Thus, these consecutive acidic amino acid residues were found to be core residues regulating magnetite crystal morphology. PMID:27759096

  1. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens

    SciTech Connect

    Byrne, J. M.; Telling, N. D.; Coker, V. S.; Pattrick, R. A. D.; Laan, G. van der; Arenholz, E.; Tuna, F.; Lloyd, J. R.

    2011-08-02

    The bioproduction of nano-scale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens, by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles has been investigated by X-ray magnetic circular dichroism and indicates the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimised biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently in the less harmful trivalent form.

  2. Sticking polydisperse hydrophobic magnetite nanoparticles to lipid membranes.

    PubMed

    Paulus, Michael; Degen, Patrick; Brenner, Thorsten; Tiemeyer, Sebastian; Struth, Bernd; Tolan, Metin; Rehage, Heinz

    2010-10-19

    The formation of a layer of hydrophobic magnetite (Fe(3)O(4)) nanoparticles stabilized by lauric acid is analyzed by in situ X-ray reflectivity measurements. The data analysis shows that the nanoparticles partially disperse their hydrophobic coating. Consequently, a Langmuir layer was formed by lauric acid molecules that can be compressed into an untilted condensed phase. A majority of the nanoparticles are attached to the Langmuir film integrating lauric acid residue on their surface into the Langmuir film. Hence, the particles at the liquid-gas interface can be identified as so-called Janus beads, which are amphiphilic solids having two sides with different functionality.

  3. Superexchange coupling on oleylsarcosine-coated magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Bakuzis, A. F.; Pereira, A. R.; Santos, J. G.; Morais, P. C.

    2006-04-01

    Room temperature ferromagnetic resonance was used to investigate particle-particle interaction in magnetic fluid samples containing magnetite nanoparticles surface coated with dimercaptosuccinic acid (DMSA) or oleylsarcosine (OLEL). The DMSA sample showed a decrease of the magnetic resonance field (MRF) increasing the nanoparticle concentration (phi), whereas the OLEL sample showed the opposite behavior. The DMSA MRF concentration dependence was explained using a dipolar interaction model beyond the point dipole approximation. In addition, the magnetic resonance spectra of the OLEL sample showed an optical mode suggesting an antiferromagnetic superexchange coupling between magnetic nanoparticles forming dimers.

  4. Synthesis of environmentally friendly highly dispersed magnetite nanoparticles based on rosin cationic surfactants as thin film coatings of steel.

    PubMed

    Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; Al-Hussain, Sami A

    2014-04-22

    This work presents a new method to prepare monodisperse magnetite nanoparticles capping with new cationic surfactants based on rosin. Core/shell type magnetite nanoparticles were synthesized using bis-N-(3-levopimaric maleic acid adduct-2-hydroxy) propyl-triethyl ammonium chloride (LPMQA) as capping agent. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the nanoparticles chemical structure. Transmittance electron microscopies (TEM) and X-ray powder diffraction (XRD) were used to examine the morphology of the modified magnetite nanoparticles. The magnetite dispersed aqueous acid solution was evaluated as an effective anticorrosion behavior of a hydrophobic surface on steel. The inhibition effect of magnetite nanoparticles on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Results obtained from both potentiodynamic polarisation and EIS measurements reveal that the magnetite nanoparticle is an effective inhibitor for the corrosion of steel in 1.0 M HCl solution. Polarization data show that magnetite nanoparticles behave as a mixed type inhibitor. The inhibition efficiencies obtained from potentiodynamic polarization and EIS methods are in good agreement.

  5. Synthesis of Environmentally Friendly Highly Dispersed Magnetite Nanoparticles Based on Rosin Cationic Surfactants as Thin Film Coatings of Steel

    PubMed Central

    Atta, Ayman M.; El-Mahdy, Gamal A.; Al-Lohedan, Hamad A.; Al-Hussain, Sami A.

    2014-01-01

    This work presents a new method to prepare monodisperse magnetite nanoparticles capping with new cationic surfactants based on rosin. Core/shell type magnetite nanoparticles were synthesized using bis-N-(3-levopimaric maleic acid adduct-2-hydroxy) propyl-triethyl ammonium chloride (LPMQA) as capping agent. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the nanoparticles chemical structure. Transmittance electron microscopies (TEM) and X-ray powder diffraction (XRD) were used to examine the morphology of the modified magnetite nanoparticles. The magnetite dispersed aqueous acid solution was evaluated as an effective anticorrosion behavior of a hydrophobic surface on steel. The inhibition effect of magnetite nanoparticles on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Results obtained from both potentiodynamic polarisation and EIS measurements reveal that the magnetite nanoparticle is an effective inhibitor for the corrosion of steel in 1.0 M HCl solution. Polarization data show that magnetite nanoparticles behave as a mixed type inhibitor. The inhibition efficiencies obtained from potentiodynamic polarization and EIS methods are in good agreement. PMID:24758936

  6. Trichloroethylene degradation by persulphate with magnetite as a heterogeneous activator in aqueous solution.

    PubMed

    Ruan, Xiaoxin; Gu, Xiaogang; Lu, Shuguang; Qiu, Zhaofu; Sui, Qian

    2015-01-01

    Iron oxide-magnetite (Fe3O4) as a heterogeneous activator to activate persulphate anions (S2O8(2-)) for trichloroethylene (TCE) degradation was investigated in this study. The experimental results showed that TCE could be completely oxidized within 5 h by using 5 g L(-1) magnetite and 63 mM S2O8(2-), indicating the effectiveness of the process for TCE removal. Various factors of the process, including. (S2O8(2-) and magnetite dosages, and initial solution pH, were evaluated, and TCE degradation fitted well to the pseudo-first-order kinetic model. The calculated kinetic rate constant was increased with increasing S2O8(2-) and magnetite dosages, but it was independent of solution pH. In addition, the changes of magnetite morphology examined by scanning electron microscopy and X-ray powder diffraction, respectively, confirmed the slight corrosion with α-Fe2O3 coated on the magnetite surface. The probe compounds tests clearly identified the generation of the reactive oxygen species in the system. While the free radical quenching studies further demonstrated that •SO4- and •OH were the major radicals responsible for TCE degradation, whereas •O2- contributed less in the system, and therefore the roles of reactive oxygen species on TCE degradation mechanisms were proposed accordingly. To our best knowledge, this is the first time the performance and mechanism of magnetite-activated persulphate oxidation for TCE degradation are reported. The findings of this study provided a new insight into the heterogeneous catalysis mechanism and showed a great potential for the practical application of this technique in in situ TCE-contaminated groundwater remediation.

  7. High Efficiency DNA Extraction by Graphite Oxide/Cellulose/Magnetite Composites Under Na+ Free System

    NASA Astrophysics Data System (ADS)

    Akceoglu, Garbis Atam; Li, Oi Lun; Saito, Nagahiro

    2016-04-01

    DNA extraction is the key step at various research areas like biotechnology, diagnostic development, paternity determination, and forensic science . Solid support extraction is the most common method for DNA purification. In this method, Na+ ions have often been applied as binding buffers in order to obtain high extraction efficiency and high quality of DNA; however, the presence of Na+ ions might be interfering with the downstream DNA applications. In this study, we proposed graphite oxide (GO)/magnetite composite/cellulose as an innovative material for Na+-free DNA extraction. The total wt.% of GO was fixed at 4.15% in the GO/cellulose/magnetite composite . The concentration of magnetite within the composites were controlled at 0-3.98 wt.%. The extraction yield of DNA increased with increasing weight percentage of magnetite. The highest yield was achieved at 3.98 wt.% magnetite, where the extraction efficiency was reported to be 338.5 ng/µl. The absorbance ratios between 260 nm and 280 nm (A260/A280) of the DNA elution volume was demonstrated as 1.81, indicating the extracted DNA consisted of high purity. The mechanism of adsorption of DNA was provided by (1) π-π interaction between the aromatic ring in GO and nucleobases of DNA molecule, and (2) surface charge interaction between the positive charge magnetite and anions such as phosphates within the DNA molecules. The results proved that the GO/cellulose/magnetite composite provides a Na+-free method for selective DNA extraction with high extraction efficiency of pure DNA.

  8. Oxidation of pyrite in coal to magnetite

    USGS Publications Warehouse

    Thorpe, A.N.; Senftle, F.E.; Alexander, C.C.; Dulong, F.T.

    1984-01-01

    When bituminous coal is heated in an inert atmosphere (He) containing small amounts of oxygen at 393-455 ??C, pyrite (FeS2) in coal is partially converted to magnetite (Fe304). The maximum amount of Fe304 formed during the time of heating corresponds to 5-20% of the total pyrite present, depending on the coal sample. The magnetite forms as an outer crust on the pyrite grains. The fact that the magnetic properties of the pyrite grains are substantially increased by the magnetite crust suggests that pyrite can be separated from coal by use of a low magnetic field. In a laboratory test, 75% removal is obtained by means of a 500 Oe magnet on three samples, and 60% on a fourth sample. ?? 1984.

  9. Scaffold of Asymmetric Organic Compounds - Magnetite Plaquettes

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.; Martinez, J.

    2015-01-01

    Life on Earth shows preference towards the set of organics with particular spatial configurations, this 'selectivity' is a crucial criterion for life. With only rare exceptions, life prefers the left- (L-) form over the right- (D-) form of amino acids, resulting in an L-enantiomeric excess (L-ee). Recent studies have shown Lee for alpha-methyl amino acids in some chondrites. Since these amino acids have limited terrestrial occurrence, the origin of their stereoselectivity is nonbiological, and it seems appropriate to conclude that chiral asymmetry, the molecular characteristic that is common to all terrestrial life form, has an abiotic origin. A possible abiotic mechanism that can produce chiral asymmetry in meteoritic amino acids is their formation with the presence of asymmetric catalysts, as mineral crystallization can produce spatially asymmetric structures. Magnetite is shown to be an effective catalyst for the formation of amino acids that are commonly found in chondrites. Magnetite 'plaquettes' (or 'platelets'), first described by Jedwab, show an interesting morphology of barrel-shaped stacks of magnetite disks with an apparent dislocation-induced spiral growth that seem to be connected at the center. A recent study by Singh et al. has shown that magnetites can self-assemble into helical superstructures. Such molecular asymmetry could be inherited by adsorbed organic molecules. In order to understand the distribution of 'spiral' magnetites in different meteorite classes, as well as to investigate their apparent spiral configurations and possible correlation to molecular asymmetry, we observed polished sections of carbonaceous chondrites (CC) using scanning electron microscope (SEM) imaging. The sections were also studied by electron backscattered diffraction (EBSD) in order to reconstruct the crystal orientation along the stack of magnetite disks.

  10. Rock magnetism linked to human brain magnetite

    NASA Astrophysics Data System (ADS)

    Kirschvink, Joseph L.

    Magnetite has a long and distinguished career as one of the most important minerals in geophysics, as it is responsible for most of the remanent magnetization in marine sediments and the oceanic crust. It may come as a surprise to discover that it also ranks as the third or fourth most diverse mineral product formed biochemically by living organisms, and forms naturally in a variety of human tissues [Kirschvink et al., 1992].Magnetite was discovered in teeth of the Polyplacophora mollusks over 30 years ago, in magnetotactic bacteria nearly 20 years ago, in honey bees and homing pigeons nearly 15 years ago, but only recently in human tissue.

  11. Immobilization of Peroxidase onto Magnetite Modified Polyaniline

    PubMed Central

    Barbosa, Eduardo Fernandes; Molina, Fernando Javier; Lopes, Flavio Marques; García-Ruíz, Pedro Antonio; Caramori, Samantha Salomão; Fernandes, Kátia Flávia

    2012-01-01

    The present study describes the immobilization of horseradish peroxidase (HRP) on magnetite-modified polyaniline (PANImG) activated with glutaraldehyde. After the optimization of the methodology, the immobilization of HRP on PANImG produced the same yield (25%) obtained for PANIG with an efficiency of 100% (active protein). The optimum pH for immobilization was displaced by the effect of the partition of protons produced in the microenvironment by the magnetite. The tests of repeated use have shown that PANImG-HRP can be used for 13 cycles with maintenance of 50% of the initial activity. PMID:22489198

  12. Structural and optical characterization of NaGdF4: Ho3+/Yb3+ UC nano-particles for lateral finger mark detections

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Tiwari, S. P.; Krishna, K. M.; Kumar, K.

    2016-05-01

    Ho3+/Yb3+ co-doped NaGdF4 up-conversion (UC) nano-particles were synthesized by thermal decomposition method. X-ray diffraction and FE-SEM image analysis were done to confirm the structure, morphology and determination of particle size. The UC emission spectra for as prepared as well as 100°C, 200°C, 300°C, 400°C, 800°C, 1000°C and 1200°C heated for 3h samples were recorded and there emission intensities were compared at a constant pump power of excitations 98.1 W/cm2. The effect of emission intensity on decay time was also studied through focused and unfocused excitations. The synthesized material was successfully utilized in lateral finger mark detections on the glass substrate through powder dusting method.

  13. Evaluation of cytotoxic, genotoxic and inflammatory responses of micro- and nano-particles of granite on human lung fibroblast cell IMR-90.

    PubMed

    Ahmad, Iqbal; Khan, Mohd Imran; Patil, Govil; Chauhan, L K S

    2012-02-05

    Occupational exposure of granite workers is well known to cause lung impairment and silicosis. Toxicological profiles of different size particles of granite dust, however, are not yet understood. Present evaluation of micro- and nano-particles of granite dust as on human lung fibroblast cells IMR-90, revealed that their toxic effects were dose-dependent, and nanoparticles in general were more toxic. In this study we first demonstrated that nanoparticles caused oxidative stress, inflammatory response and genotoxicity, as seen by nearly 2 fold induction of ROS and LPO, mRNA levels of TNF-α and IL-1β, and induction in micronuclei formation. All these were significantly higher when compared with the effect of micro particles. Thus, the study suggests that separate health safety standards would be required for granite particles of different sizes.

  14. How surface functional groups influence fracturation in nanofluids droplets dry-outs

    NASA Astrophysics Data System (ADS)

    Brutin, David; Carle, Florian

    2012-11-01

    We report an experimental investigation of the drying of a deposited droplets of nanofluids with different surface functional groups. For identical nano-particles diameter, material and concentration, identical drying conditions, the substrate and the functional groups at the nano-particles surface are changed. Both flow motion, adhesion, gelation and fracturation occur during the evaporation of this complex matter leading to different final typical patterns. The differences in between the patterns are explained based on the surface chemical potential. Crack shapes and wavelengths are globally proportional to the electrical charges carried at the nano- particles surface which is a new parameter to implement in existing predicting models. Presently only the colloid concentration and softness and the deposit thickness are used (Allain and Limat, 1995). The authors gratefully acknowledge the help and the fruitful discussions raised with J.B. Lang.

  15. Aqueous dispersions of magnetite nanoparticles complexed with copolyether dispersants: experiments and theory.

    PubMed

    Zhang, Qian; Thompson, M Shane; Carmichael-Baranauskas, Anita Y; Caba, Beth L; Zalich, Michael A; Lin, Yin-Nian; Mefford, O Thompson; Davis, Richey M; Riffle, Judy S

    2007-06-19

    Magnetite (Fe3O4) nanoparticles have been synthesized and complexed with carboxylate-functional block copolymers, and then aqueous dispersions of the complexes were investigated as functions of their chemical and morphological structures. The block copolymer dispersants had either poly(ethylene oxide), poly(ethylene oxide-co-propylene oxide), or poly(ethylene oxide-b-propylene oxide) outer blocks, and all of them had a polyurethane center block that contained pendent carboxylate groups. The complexes were formed through interactions of the carboxylates with the surfaces of the magnetite nanoparticles. The magnetite cores of the magnetite-copolymer complexes were near 10 nm in diameter, and the particles were superparamagnetic. Complexes with mass ratios of polymer to magnetite varying from 50:50 to 85:15 were studied. One of our objectives is to design complexes that form stable dispersions of discrete particles in water, yet that can be actuated (moved together) upon exposure to a uniform magnetic field. DLVO calculations that accounted for magnetic attractive interparticle forces, as well as van der Waals, steric, and electrostatic forces are presented. Compositions were identified wherein a shallow, attractive interparticle potential minimum appears once the magnetic term is applied. This suggests that it may be possible to tune the structures of superparamagnetic nanoparticle shells to allow discrete dispersions without a field, yet weak flocculation could be induced upon exposure to a field.

  16. Crystal growth of bullet-shaped magnetite in magnetotactic bacteria of the Nitrospirae phylum

    PubMed Central

    Li, Jinhua; Menguy, Nicolas; Gatel, Christophe; Boureau, Victor; Snoeck, Etienne; Patriarche, Gilles; Leroy, Eric; Pan, Yongxin

    2015-01-01

    Magnetotactic bacteria (MTB) are known to produce single-domain magnetite or greigite crystals within intracellular membrane organelles and to navigate along the Earth's magnetic field lines. MTB have been suggested as being one of the most ancient biomineralizing metabolisms on the Earth and they represent a fundamental model of intracellular biomineralization. Moreover, the determination of their specific crystallographic signature (e.g. structure and morphology) is essential for palaeoenvironmental and ancient-life studies. Yet, the mechanisms of MTB biomineralization remain poorly understood, although this process has been extensively studied in several cultured MTB strains in the Proteobacteria phylum. Here, we show a comprehensive transmission electron microscopy (TEM) study of magnetic and structural properties down to atomic scales on bullet-shaped magnetites produced by the uncultured strain MYR-1 belonging to the Nitrospirae phylum, a deeply branching phylogenetic MTB group. We observed a multiple-step crystal growth of MYR-1 magnetite: initial isotropic growth forming cubo-octahedral particles (less than approx. 40 nm), subsequent anisotropic growth and a systematic final elongation along [001] direction. During the crystal growth, one major {111} face is well developed and preserved at the larger basal end of the crystal. The basal {111} face appears to be terminated by a tetrahedral–octahedral-mixed iron surface, suggesting dimensional advantages for binding protein(s), which may template the crystallization of magnetite. This study offers new insights for understanding magnetite biomineralization within the Nitrospirae phylum. PMID:25566884

  17. Crystal growth of bullet-shaped magnetite in magnetotactic bacteria of the Nitrospirae phylum.

    PubMed

    Li, Jinhua; Menguy, Nicolas; Gatel, Christophe; Boureau, Victor; Snoeck, Etienne; Patriarche, Gilles; Leroy, Eric; Pan, Yongxin

    2015-02-06

    Magnetotactic bacteria (MTB) are known to produce single-domain magnetite or greigite crystals within intracellular membrane organelles and to navigate along the Earth's magnetic field lines. MTB have been suggested as being one of the most ancient biomineralizing metabolisms on the Earth and they represent a fundamental model of intracellular biomineralization. Moreover, the determination of their specific crystallographic signature (e.g. structure and morphology) is essential for palaeoenvironmental and ancient-life studies. Yet, the mechanisms of MTB biomineralization remain poorly understood, although this process has been extensively studied in several cultured MTB strains in the Proteobacteria phylum. Here, we show a comprehensive transmission electron microscopy (TEM) study of magnetic and structural properties down to atomic scales on bullet-shaped magnetites produced by the uncultured strain MYR-1 belonging to the Nitrospirae phylum, a deeply branching phylogenetic MTB group. We observed a multiple-step crystal growth of MYR-1 magnetite: initial isotropic growth forming cubo-octahedral particles (less than approx. 40 nm), subsequent anisotropic growth and a systematic final elongation along [001] direction. During the crystal growth, one major {111} face is well developed and preserved at the larger basal end of the crystal. The basal {111} face appears to be terminated by a tetrahedral-octahedral-mixed iron surface, suggesting dimensional advantages for binding protein(s), which may template the crystallization of magnetite. This study offers new insights for understanding magnetite biomineralization within the Nitrospirae phylum.

  18. Extensive FE-SEM/EDS, HR-TEM/EDS and ToF-SIMS studies of micron- to nano-particles in anthracite fly ash.

    PubMed

    Ribeiro, Joana; DaBoit, Kátia; Flores, Deolinda; Kronbauer, Marcio A; Silva, Luis F O

    2013-05-01

    The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100 nm size range by worldwide coal power plants represents serious environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples. Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1 nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis.

  19. Preparation of hollow magnetite microspheres and their applications as drugs carriers

    PubMed Central

    2012-01-01

    Hollow magnetite microspheres have been synthesized by a simple process through a template-free hydrothermal approach. Hollow microspheres were surface modified by coating with a silica nanolayer. Pristine and modified hollow microparticles were characterized by field-emission electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, FT-IR and Raman spectroscopy, and VSM magnetometry. The potential application of the modified hollow magnetite microspheres as a drug carrier was evaluated by using Rhodamine B and methotrexate as model drugs. The loading and release kinetics of both molecules showed a clear pH and temperature dependent profile. Graphical abstract Hollow magnetite microspheres have been synthesized. Load-release experiments with Rhodamine-B as a model drug and with Methotrexate (chemotherapy drug used in treating certain types of cancer) demonstrated the potential applications of these nanostructures in biomedical applications. PMID:22490731

  20. Sustained release of doxorubicin from zeolite magnetite nanocomposites prepared by mechanical activation

    NASA Astrophysics Data System (ADS)

    Arruebo, Manuel; Fernández-Pacheco, Rodrigo; Irusta, Silvia; Arbiol, Jordi; Ibarra, M. Ricardo; Santamaría, Jesús

    2006-08-01

    Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g-1 and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure, (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications.

  1. Vortex magnetic structure in framboidal magnetite reveals existence of water droplets in an ancient asteroid

    NASA Astrophysics Data System (ADS)

    Kimura, Yuki; Sato, Takeshi; Nakamura, Norihiro; Nozawa, Jun; Nakamura, Tomoki; Tsukamoto, Katsuo; Yamamoto, Kazuo

    2013-10-01

    The majority of water has vanished from modern meteorites, yet there remain signatures of water on ancient asteroids. How and when water disappeared from the asteroids is important, because the final fluid-concentrated chemical species played critical roles in the early evolution of organics and in the final minerals in meteorites. Here we show evidence of vestigial traces of water based on a nanometre-scale palaeomagnetic method, applying electron holography to the framboids in the Tagish Lake meteorite. The framboids are colloidal crystals composed of three-dimensionally ordered magnetite nanoparticles and therefore are only able to form against the repulsive force induced by the surface charge of the magnetite as a water droplet parches in microgravity. We demonstrate that the magnetites have a flux closure vortex structure, a unique magnetic configuration in nature that permits the formation of colloidal crystals just before exhaustion of water from a local system within a hydrous asteroid.

  2. Synthesis of functionalized magnetite nanoparticles to use as liver targeting MRI contrast agent

    NASA Astrophysics Data System (ADS)

    Yazdani, Farshad; Fattahi, Bahare; Azizi, Najmodin

    2016-05-01

    The aim of this research was the preparation of functionalized magnetite nanoparticles to use as a liver targeting contrast agent in magnetic resonance imaging (MRI). For this purpose, Fe3O4 nanoparticles were synthesized via the co-precipitation method. The synthesized nanoparticles were coated with silica via the Stober method and finally the coated nanoparticles were functionalized with mebrofenin. Formation of crystalline magnetite particles was confirmed by X-ray diffraction (XRD) analysis. The Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray analyzer (EDX) of the final product showed that silica had been effectively bonded onto the surface of the magnetite nanoparticles and the coated nanoparticles functionalized with mebrofenin. The magnetic resonance imaging of the functional nanoparticles showed that the Fe3O4-SiO2-mebrofenin composite is an effective MRI contrast agent for liver targeting.

  3. Magnetite in Black Sea Turtles (Chelonia agassizi)

    NASA Astrophysics Data System (ADS)

    Fuentes, A.; Urrutia-Fucugauchi, J.; Garduño, V.; Sanchez, J.; Rizzi, A.

    2004-12-01

    Previous studies have reported experimental evidence for magnetoreception in marine turtles. In order to increase our knowledge about magnetoreception and biogenic mineralization, we have isolated magnetite particles from the brain of specimens of black sea turtles Chelonia agassizi. Our samples come from natural deceased organisms collected the reserve area of Colola Maruata in southern Mexico. The occurrence of magnetite particles in brain tissue of black sea turtles offers the opportunity for further studies to investigate possible function of ferrimagnetic material, its mineralogical composition, grain size, texture and its location and structural arrangement within the host tissue. After sample preparation and microscopic examination, we localized and identified the ultrafine unidimensional particles of magnetite by scanning electron microscope (SEM). Particles present grain sizes between 10.0 to 40.0Mm. Our study provides, for the first time, evidence for biogenic formation of this material in the black sea turtles. The ultrafine particles are apparently superparamagnetic. Preliminary results from rock magnetic measurements are also reported and correlated to the SEM observations. The black turtle story on the Michoacan coast is an example of formerly abundant resource which was utilized as a subsistence level by Nahuatl indigenous group for centuries, but which is collapsing because of intensive illegal commercial exploitation. The most important nesting and breeding grounds for the black sea turtle on any mainland shore are the eastern Pacific coastal areas of Maruata and Colola, in Michoacan. These beaches are characterized by important amounts of magnetic mineral (magnetites and titanomagnetites) mixed in their sediments.

  4. Magnetite Nanoparticles Prepared By Spark Erosion

    NASA Astrophysics Data System (ADS)

    Maiorov, M.; Blums, E.; Kronkalns, G.; Krumina, A.; Lubane, M.

    2016-08-01

    In the present research, we study a possibility of using the electric spark erosion method as an alternative to the method of chemical co-precipitation for preparation of magnetic nanoparticles. Initiation of high frequency electric discharge between coarse iron particles under a layer of distilled water allows obtaining pure magnetite nanoparticles.

  5. The metal-insulator transition in magnetite.

    NASA Technical Reports Server (NTRS)

    Cullen, J. R.; Callen, E.

    1972-01-01

    We describe an electronic model for the low temperature transition in magnetite, in which the average number of electrons on a site is non-integral. The solution of the one-dimensional problem is reviewed, and the connection of the model with the Verwey ordering is discussed. Some of the implication of the three dimensional problem are discussed.

  6. Charge ordering and ferroelectricity in magnetite

    NASA Astrophysics Data System (ADS)

    Khomskii, Daniel

    2007-03-01

    Magnetite Fe3O4 is one of the most fascinating material in solid state physics. Besides being the first magnetic material known to the mankind, it is also the first example of an insulator-metal transition in transition metal oxides -- the famous Verwey transition [1]. One usually connects this transition with the charge ordering of Fe^2+ and Fe^3+. However the detailed pattern of CO in Fe3O4 is still a matter of debate. Another aspect, which is not so widely known and which did not yet receive sufficient attention, is that below TV, besides being completely spin polarised, magnetite apparently is also ferroelectric (FE) [2]. Thus it seems that magnetite, besides being the first magnetic material and the first transition metal oxide with an insulator-metal transition, is also the first multiferroic material. Using the idea of a coexistence of site-centred and bond-centred charge ordering [3], I suggest a novel type of ordering in magnetite which explains the observed FE in Fe3O4 and which agrees with the structural data. [1] Verwey E.J.W., Nature 144, 327 (1939) [2] Rado G.T. and Ferrari J.M., Phys.Rev.B 12, 5166 (1975); Kato K. and Iida S., J.Phys.Soc.Japan 50, 2844 (1981) [3] Efremov D.V., van den Brink J. and Khomskii D.I., Nature Mater. 3, 853 (2004)

  7. Magnetite biomineralization and ancient life on Mars.

    PubMed

    Frankel, R B; Buseck, P R

    2000-04-01

    Certain chemical and mineral features of the Martian meteorite ALH84001 were reported in 1996 to be probable evidence of ancient life on Mars. In spite of new observations and interpretations, the question of ancient life on Mars remains unresolved. Putative biogenic, nanometer magnetite has now become a leading focus in the debate.

  8. Bisphosphonate release profiles from magnetite microspheres.

    PubMed

    Miyazaki, Toshiki; Inoue, Tatsuya; Shirosaki, Yuki; Kawashita, Masakazu; Matsubara, Takao; Matsumine, Akihiko

    2014-10-01

    Hyperthermia has been suggested as a novel, minimally invasive cancer treatment method. After implantation of magnetic nano- or microparticles around a tumour through blood vessels, irradiation with alternating magnetic fields facilitates the efficient in situ hyperthermia even for deep-seated tumours. On the basis of this idea, if the microspheres are capable of delivering drugs, they could be promising multifunctional biomaterials effective for chemotherapy as well as hyperthermia. In the present study, magnetite microspheres were prepared by aggregation of the iron oxide colloid in water-in-oil (W/O) emulsion. The release behaviour of alendronate, a typical bisphosphonate, from the microspheres was examined in vitro as a model of the bone tumour prevention and treatment system. The alendronate was successfully incorporated onto the porous magnetite microspheres in vacuum conditions. The drug-loaded microspheres maintained their original spherical shapes even after shaking in ultrapure water for 3 days, suggesting that they have sufficient mechanical integrity for clinical use. It was attributed to high aggregation capability of the magnetite nanoparticles through van der Waals and weak magnetic attractions. The microspheres showed slow release of the alendronate in vitro, resulting from tight covalent or ionic interaction between the magnetite and the alendronate. The release rate was diffusion-controlled type and well controlled by the alendronate concentration in drug incorporation to the microspheres.

  9. Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles

    PubMed Central

    Byrne, James M.; van der Laan, Gerrit; Figueroa, Adriana I.; Qafoku, Odeta; Wang, Chongmin; Pearce, Carolyn I.; Jackson, Michael; Feinberg, Joshua; Rosso, Kevin M.; Kappler, Andreas

    2016-01-01

    The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100–200 nm). By integrating surface-sensitive and bulk-sensitive measurement techniques we observed a particle surface that was enriched in Fe(II) with respect to a more oxidized core. This enables microbial Fe(II) oxidation to occur relatively easily at the surface of the mineral suggesting that the electron transfer is dependent upon particle size. However, microbial Fe(III) reduction proceeds via conduction of electrons into the particle interior, i.e. it can be considered as more of a bulk electron transfer process that is independent of particle size. The finding has potential implications on the ability of magnetite to be used for long range electron transport in soils and sediments. PMID:27492680

  10. Size dependent microbial oxidation and reduction of magnetite nano- and micro-particles

    NASA Astrophysics Data System (ADS)

    Byrne, James M.; van der Laan, Gerrit; Figueroa, Adriana I.; Qafoku, Odeta; Wang, Chongmin; Pearce, Carolyn I.; Jackson, Michael; Feinberg, Joshua; Rosso, Kevin M.; Kappler, Andreas

    2016-08-01

    The ability for magnetite to act as a recyclable electron donor and acceptor for Fe-metabolizing bacteria has recently been shown. However, it remains poorly understood whether microbe-mineral interfacial electron transfer processes are limited by the redox capacity of the magnetite surface or that of whole particles. Here we examine this issue for the phototrophic Fe(II)-oxidizing bacteria Rhodopseudomonas palustris TIE-1 and the Fe(III)-reducing bacteria Geobacter sulfurreducens, comparing magnetite nanoparticles (d ≈ 12 nm) against microparticles (d ≈ 100–200 nm). By integrating surface-sensitive and bulk-sensitive measurement techniques we observed a particle surface that was enriched in Fe(II) with respect to a more oxidized core. This enables microbial Fe(II) oxidation to occur relatively easily at the surface of the mineral suggesting that the electron transfer is dependent upon particle size. However, microbial Fe(III) reduction proceeds via conduction of electrons into the particle interior, i.e. it can be considered as more of a bulk electron transfer process that is independent of particle size. The finding has potential implications on the ability of magnetite to be used for long range electron transport in soils and sediments.

  11. Magnetically recyclable magnetite-palladium (Nanocat-Fe-Pd) nanocatalyst for the Buchwald-Hartwig reaction

    EPA Science Inventory

    The immobilization of Pd on magnetite surface afforded (Nanocat-Fe-Pd) using inexpensive precursors and its catalytic role in the Buchwald-Hartwig reaction for arylation of amines and amides was investigated; C-N bond formation was achieved in moderate to excellent yields and the...

  12. First-order metal-insulator transition and infrared identification of shape-controlled magnetite nanocrystals

    NASA Astrophysics Data System (ADS)

    Zheng, Lei; Su, Wei; Qi, Zeming; Xu, Yang; Zhou, Min; Xie, Yi

    2011-12-01

    The first-order metal-insulator transition (MIT) in magnetite has been known for a long time but is still controversial in its nature. In this study, well-defined magnetite nanocrystals (NCs) with controllable size, shape and terminated surface are first employed to elucidate this important issue, and new discoveries such as a highly suppressed phase transition temperature are identified by monitoring the variable-temperature electric resistance and infrared spectroscopy. Significantly, by carefully comparing the infrared vibrational bands of the as-prepared magnetite NCs with octahedral and cubic shapes, respectively, we found that these two forms of magnetite NCs exhibited different transmittance changes and frequency shifts of the infrared characteristics, presumably due to the differences in the lattice distortions on the corresponding {001} and {111} terminal surfaces. This result produced evidence in support of the charge ordering of Fe atoms along the low dimensionality at octahedral B sites undergoing the MIT. Taken together, infrared identification was proposed to be an available characterization strategy for MIT, which can reflect more information on the elusive lattice distortion of crystallographic structure or exposed surfaces.

  13. Adsorption-desorption mechanism of phosphate by immobilized nano-sized magnetite layer: interface and bulk interactions.

    PubMed

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

    2011-11-15

    Phosphate adsorption mechanism by a homogenous porous layer of nano-sized magnetite particles immobilized onto granular activated carbon (nFe-GAC) was studied for both interface and bulk structures. X-ray Photoelectron Spectroscopy (XPS) analysis revealed phosphate bonding to the nFe-GAC predominantly through bidentate surface complexes. It was established that phosphate was adsorbed to the magnetite surface mainly via ligand exchange mechanism. Initially, phosphate was adsorbed by the active sites on the magnetite surface, after which it diffused into the interior of the nano-magnetite layer, as indicated by intraparticle diffusion model. This diffusion process continues regardless of interface interactions, revealing some of the outer magnetite binding sites for further phosphate uptake. Desorption, using NaOH solution, was found to be predominantly a surface reaction, at which hydroxyl ions replace the adsorbed phosphate ions only at the surface outer biding sites. Five successive fix-bed adsorption/regeneration cycles were successfully applied, without significant reduction in the nFe-GAC adsorption capacity and at high regeneration efficiency.

  14. Moessbauer Characterization of Magnetite/Polyaniline Magnetic Nanocomposite

    SciTech Connect

    Rodriguez, Anselmo F. R.; Faria, Fernando S. E. D. V.; Lopez, Jorge L.; Mesquita, Antonio G. G.; Coaquira, Jose A. H.; Oliveira, Aderbal C.; Morais, Paulo C.; Azevedo, Ricardo B.; Araujo, Ana C. V. de; Alves, Severino Jr.; Azevedo, Walter M. de

    2010-12-02

    Aniline surface coated Fe{sub 3}O{sub 4} nanoparticles have been successfully synthesized by UV irradiation varying the time and the acid media (HCl, HNO{sub 3}, or H{sub 2}SO{sub 4}). The synthesized material represents a promising platform for application in nerve regeneration. XRD patterns are consistent with the crystalline structure of magnetite. Nevertheless, for UV irradiation times longer than 2 h, extra XRD lines reveal the presence of goethite. The mean crystallite size of uncoated particles is estimated to be 25.4 nm, meanwhile that size is reduced to 19.9 nm for the UV irradiated sample in HCl medium for 4 h. Moessbauer spectra of uncoated nanoparticles reveal the occurrence of thermal relaxation at room temperature, while the 77 K-Moessbauer spectrum suggests the occurrence of electron localization effects similar to that expected in bulk magnetite. The Mossbauer spectra of UV irradiated sample in HCl medium during 4 h, confirms the presence of the goethite phase. For this sample, the thermal relaxation is more evident, since the room temperature spectrum shows larger spectral area for the nonmagnetic component due to the smaller crystallite size. Meanwhile, the 77 K-Moessbauer spectrum suggests the absence of the electron localization effect above 77 K.

  15. Magnetic Core-Shell Morphology of Structurally Uniform Magnetite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Krycka, Kathryn

    2011-03-01

    Magnetic nanoscale structures are intriguing, in part, because of the exotic properties that emerge compared with bulk. The reduction of magnetic moment per atom in magnetite with decreasing nanoparticle size, for example, has been hypothesized to originate from surface disordering to anisotropy-induced radial canting, which are difficult to distinguish using conventional magnetometry. Small-angle neutron scattering (SANS) is ideal for probing structure, both chemical and magnetic, from nm to microns across an ensemble of particles. Adding polarization analysis (PASANS) of the neutron spin orientation before and after interaction with the scattering particles allows the magnetic structure to be separated into its vector components. Application of this novel technique to 9 nm magnetite nanoparticles closed-packed into face-centered crystallites with order of a micron revealed that at nominal saturation the missing magnetic moments unexpectedly interacted to form well-ordered shells 1.0 to 1.5 nm thick canted perpendicular to their ferrimagnetic cores between 160 to 320 K. These shells additionally displayed intra-particle ``cross-talk'', selecting a common orientation over clusters of tens of nanoparticles. However, the shells disappeared when the external field was removed and interparticle magnetic interactions were negligible (300 K), confirming their magnetic origin. This work has been carried out in collaboration with Ryan Booth, Julie Borchers, Wangchun Chen, Liv Dedon, Thomas Gentile, Charles Hogg, Yumi Ijiri, Mark Laver, Sara Majetich, James Rhyne, and Shannon Watson.

  16. Preparation and application of crosslinked poly(sodium acrylate)--coated magnetite nanoparticles as corrosion inhibitors for carbon steel alloy.

    PubMed

    Atta, Ayman M; El-Mahdy, Gamal A; Al-Lohedan, Hamad A; El-Saeed, Ashraf M

    2015-01-14

    This work presents a new method to prepare poly(sodium acrylate) magnetite composite nanoparticles. Core/shell type magnetite nanocomposites were synthesized using sodium acrylate as monomer and N,N-methylenebisacrylamide (MBA) as crosslinker. Microemulsion polymerization was used for constructing core/shell structures with magnetite nanoparticles as core and poly(sodium acrylate) as shell. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the nanocomposite chemical structure. Transmittance electron microscopy (TEM) was used to examine the morphology of the modified poly(sodium acrylate) magnetite composite nanoparticles. These particle will be evaluated for effective anticorrosion behavior as a hydrophobic surface on stainless steel. The composite nanoparticles has been designed by dispersing nanocomposites which act as a corrosion inhibitor. The inhibition effect of AA-Na/magnetite composites on steel corrosion in 1 M HCl solution was investigated using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Polarization measurements indicated that the studied inhibitor acts as mixed type corrosion inhibitor. EIS spectra exhibit one capacitive loop. The different techniques confirmed that the inhibition efficiency reaches 99% at 50 ppm concentration. This study has led to a better understanding of active anticorrosive magnetite nanoparticles with embedded nanocomposites and the factors influencing their anticorrosion performance.

  17. Multiple morphologies of gold-magnetite heterostructure nanoparticles are effectively functionalized with protein for cell targeting.

    PubMed

    Krystofiak, Evan S; Mattson, Eric C; Voyles, Paul M; Hirschmugl, Carol J; Albrecht, Ralph M; Gajdardziska-Josifovska, Marija; Oliver, Julie A

    2013-08-01

    Nanoparticles composed of a magnetic iron oxide core surrounded by a metal shell have utility in a broad range of biomedical applications. However, the presence of surface energy differences between the two components makes wetting of oxide with metal unfavorable, precluding a "core-shell" structure of an oxide core completely surrounded by a thin metal shell. Three-dimensional island growth followed by island coalescence into thick shells is favored over the two-dimensional layer-by-layer growth of a thin, continuous metal coating of a true core-shell. Aqueous synthesis of gold-coated magnetite nanoparticles with analysis by infrared, energy-dispersive X-ray, and electron energy loss spectroscopies; high-resolution transmission electron microscopy; selected area electron diffraction; and high-angle annular dark-field scanning transmission electron microscopy showed two distinct morphologies that are inconsistent with an idealized core-shell. The majority were isolated ~16-22-nm-diameter nanoparticles consisting of ~7-nm-diameter magnetite and a thick deposition of gold, most often discontinuous, with some potentially "sandwiched" morphologies. A minority were aggregates of agglomerated magnetite decorated with gold but displaying significant bare magnetite. Both populations were successfully conjugated to fibrinogen and targeted to surface-activated platelets, demonstrating that iron oxide-gold nanoparticles produced by aqueous synthesis do not require an ideal core-shell structure for biological activity in cell labeling and targeting applications.

  18. Initial Test Determination of Cosmogenic Nuclides in Magnetite

    NASA Astrophysics Data System (ADS)

    Matsumura, H.; Caffee, M. W.; Nagao, K.; Nishiizumi, K.

    2014-12-01

    Long-lived radionuclides, such as 10Be, 26Al, and 36Cl, are produced by cosmic rays in surficial materials on Earth, and used for determinations of cosmic-ray exposure ages and erosion rates. Quartz and limestone are routinely used as the target minerals for these geomorphological studies. Magnetite also contains target elements that produce abundant cosmogenic nuclides when exposed to the cosmic rays. Magnetite has several notable merits that enable the measurement of cosmogenic nuclides: (1) the target elements for production of cosmogenic nuclides in magnetite comprise the dominant mineral form of magnetite, Fe3O4; (2) magnetite can be easily isolated, using a magnet, after rock milling; (3) multiple cosmogenic nuclides are produced by exposure of magnetite to cosmic-ray secondaries; and (4) cosmogenic nuclides produced in the rock containing the magnetite, but not within the magnetite itself, can be separated using nitric acid and sodium hydroxide leaches. As part of this initial study, magnetite was separated from a basaltic sample collected from the Atacama Desert in Chili (2,995 m). Then Be, Al, Cl, Ca, and Mn were separated from ~2 g of the purified magnetite. We measured cosmogenic 10Be, 26Al, and 36Cl concentrations in the magnetite by accelerator mass spectrometry at PRIME Lab, Purdue University. Cosmogenic 3He and 21Ne concentrations of aliquot of the magnetite were measured by mass spectrometry at the University of Tokyo. We also measured the nuclide concentrations from magnetite collected from a mine at Ishpeming, Michigan as a blank. The 10Be and 36Cl concentrations as well as 3He concentration produce concordant cosmic ray exposure ages of ~0.4 Myr for the Atacama basalt. However, observed high 26Al and 21Ne concentrations attribute to those nuclides incorporation from silicate impurity.

  19. Molecular simulation of the magnetite-water interface

    NASA Astrophysics Data System (ADS)

    Rustad, James R.; Felmy, Andrew R.; Bylaska, Eric J.

    2003-03-01

    This paper reports molecular dynamics simulations of the magnetite (001)-water interface, both in pure water and in the presence of a 2.3 molal solution of NaClO 4. The simulations are carried out using a potential model designed to allow the protonation states of the surface functional groups to evolve dynamically through the molecular dynamics trajectory. The primary structural quantities investigated are the populations of the surface functional groups, the distribution of electrolyte in the solution, and the surface hydrogen bonding relationships. The surface protonation states are dominated by extensive hydrolysis of interfacial water molecules, giving rise to a dipolar surface dominated by FeOH2+-OH 2-OH - arrangements. Triply coordinated, more deeply buried, surface sites are inert, probably due to the relative lack of solvent in their vicinity. The electrolyte distribution is oscillatory, arranging preferentially in layers defined by the solvating water molecules. The presence of electrolyte has a negligible effect on the protonation states of the surface functional groups. Steady-state behavior is obtained for the protonation states of the surface functional groups and hydrogen-bonding network. Although the overall structure of the electrolyte distribution is fairly well established, the electrolyte distribution has not fully equilibrated, as evidenced by the asymmetry in the distribution from the top to the bottom of the slab.

  20. Experimental Shock Decomposition of Siderite to Magnetite

    NASA Technical Reports Server (NTRS)

    Bell, M. S.; Golden, D. C.; Zolensky, M. E.

    2005-01-01

    The debate about fossil life on Mars includes the origin of magnetites of specific sizes and habits in the siderite-rich portions of the carbonate spheres in ALH 84001 [1,2]. Specifically [2] were able to demonstrate that inorganic synthesis of these compositionally zoned spheres from aqueous solutions of variable ion-concentrations is possible. They further demonstrated the formation of magnetite from siderite upon heating at 550 C under a Mars-like CO2-rich atmosphere according to 3FeCO3 = Fe3O4 + 2CO2 + CO [3] and they postulated that the carbonates in ALH 84001 were heated to these temperatures by some shock event. The average shock pressure for ALH 84001, substantially based on the refractive index of diaplectic feldspar glasses [3,4,5] is some 35-40 GPa and associated temperatures are some 300-400 C [4]. However, some of the feldspar is melted [5], requiring local deviations from this average as high as 45-50 GPa. Indeed, [5] observes the carbonates in ALH 84001 to be melted locally, requiring pressures in excess of 60 GPa and temperatures > 600 C. Combining these shock studies with the above inorganic synthesis of zoned carbonates it seems possible to produce the ALH 84001 magnetites by the shock-induced decomposition of siderite.

  1. An XPS study for mechanisms of arsenate adsorption onto a magnetite-doped activated carbon fiber.

    PubMed

    Zhang, Shujuan; Li, Xiao-yan; Chen, J Paul

    2010-03-01

    The surface and bulk structures of a newly developed carbon-based iron-containing adsorbent for As(V) adsorption were investigated by using X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). XRD patterns of the adsorbents indicated that the modified activated carbon fiber (MACF) was a simple mixture of the raw activated carbon fiber (RACF) and magnetite. After modification, a porous film was formed on the surface of the MACF with nano-sized magnetite on it. The As(V) uptake on the MACF was highly pH dependent and was facilitated in acidic solutions. XPS studies demonstrated that the surface oxygen-containing functional groups were involved in the adsorption and that magnetite played a key role in As(V) uptake. The dominance of HAsO(4)(2-) in surface complexes and the pH effect on As(V) uptake demonstrated that the monoprotonated bidentate complexes were dominant on the surface of the MACF. No reduction of As(V) was observed on the surface of the ACFs.

  2. Modification of carbon paste electrode with Fe(III)-clinoptilolite nano-particles for simultaneous voltammetric determination of acetaminophen and ascorbic acid.

    PubMed

    Sharifian, Samira; Nezamzadeh-Ejhieh, Alireza

    2016-01-01

    A novel carbon paste electrode (CPE) modified with Fe(III)-exchanged clinoptilolite nano-particles (Fe(III)-NClino/CPE) was constructed and used for simultaneous voltammetric (CV, SqW and chronoamperometry) determination of ascorbic acid and acetaminophen. Raw and modified zeolites were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The square wave peak current was linearly increased in the concentration ranges of 1.0 × 10(-9)-1.0 × 10(-2) mol L(-1) for ascorbic acid and 1.0 × 10(-10-)1.0 × 10(-2) mol L(-1) for acetaminophen with detection limits of 1.8 × 10(-9) mol L(-1) and 9.9 × 10(-10) mol L(-1), respectively. The detection limits of 2.4 × 10(-10) mol L(-1) and 2.5 × 10(-11) mol L(-1) were also obtained for AA and AC in chronoamperometric measurements, respectively. The diffusion coefficients of 7.5 × 10(-5) cm(2) s(-1) and 2.4 × 10(-5) cm(2) s(-1) were respectively calculated for the oxidation of AC and AA by chronoamperometry. The proposed electrode exhibited high sensitivity and good stability, and would be valuable for the clinical assay of ascorbic acid and acetaminophen.

  3. Physics-Based Simulation and Experiment on Blast Protection of Infill Walls and Sandwich Composites Using New Generation of Nano Particle Reinforced Materials

    NASA Astrophysics Data System (ADS)

    Irshidat, Mohammad

    A critical issue for the development of nanotechnology is our ability to understand, model, and simulate the behavior of small structures and to make the connection between nano structure properties and their macroscopic functions. Material modeling and simulation helps to understand the process, to set the objectives that could guide laboratory efforts, and to control material structures, properties, and processes at physical implementation. These capabilities are vital to engineering design at the component and systems level. In this research, experimental-computational-analytical program was employed to investigate the performance of the new generation of polymeric nano-composite materials, like nano-particle reinforced elastomeric materials (NPREM), for the protection of masonry structures against blast loads. New design tools for using these kinds of materials to protect Infill Walls (e.g. masonry walls) against blast loading were established. These tools were also extended to cover other type of panels like sandwich composites. This investigation revealed that polymeric nano composite materials are strain rate sensitive and have large amount of voids distributed randomly inside the materials. Results from blast experiments showed increase in ultimate flexural resistance achieved by both unreinforced and nano reinforced polyurea retrofit systems applied to infill masonry walls. It was also observed that a thin elastomeric coating on the interior face of the walls could be effective at minimizing the fragmentation resulting from blast. More conclusions are provided with recommended future research.

  4. Polymer brushes containing thermosensitive and functional groups grafted onto magnetic nano-particles for interaction and extraction of famotidine in biological samples.

    PubMed

    Ahmad Panahi, Homayon; Nasrollahi, Sara

    2014-12-10

    This study introduces a new method for grafting poly[N-isopropylacrylamide-co-allyl glycidyl/iminodiacetic] onto iron oxide nano-particles modified using 3-mercaptopropyltrimethoxysilane. The grafted nano-polymer was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, transmission electron microscopy and scanning electron microscopy. The parameters of pH, contact time and temperature of the grafted nano-polymer were investigated. The determination and extraction of famotidine in human biological fluids was evaluated for high accessibility to active sites on the grafted sorbent. The equilibrium adsorption data were analyzed using the Langmuir and Freundlich models. The sorption capacity of the nano-sorbent was 116 mg g(-1) at an optimum pH of 7. About 73% of famotidine was released into simulated gastric fluid by 1 h and 70% was released into simulated intestinal fluids by 30 h at 37 °C. These results show that this new magnetic grafted nano-polymer is suitable for enteric drug delivery.

  5. Invited paper: Sintering mechanism of vapor self-assembled multilayer (VSAM) coated Cu nano particles for application in Cu nano ink

    NASA Astrophysics Data System (ADS)

    Haque, Md. Mominul; Park, Shinyoung; Her, Jaehak; Park, Joong-Hak; Lee, Caroline Sunyong

    2011-09-01

    Oxidation preventive Cu nano ink was prepared using a vapor self-assembed multi-layer coating method (VSAMs). These particles were prepared using 100 nm Cu nano particles coated with 1-octanethiol under ultrahigh vacuum condition with octanol used as a solvent. Octanol-based non-oxidized 10% (wt.) nano ink was well-dispersed without any surfactant. The conductive ink had good dispersion and remains stable for more than 6 weeks. It also has a low viscosity rating of 8.3 cPs. In addition, 5 μL of copper nano ink was dropped into a 1 cm × 1 cm glass substrate to form a copper pattern. The copper pattern was then sintered at 350°C in a tube furnace in a H2 gas atmosphere. The resistivity of the film using the fabricated ink was determined to be 5.8 × 10-6 Ωcm. The results show that the non-oxidized oxidation-preventive copper nano ink is suitable for ink-jet printing.

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

    PubMed

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

    2016-01-01

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

  7. Sacrificial Reducing Agent Free Photo-Generation of Platinum Nano Particle over Carbon/TiO2 for Highly Efficient Oxygen Reduction Reaction

    NASA Astrophysics Data System (ADS)

    Badam, Rajashekar; Vedarajan, Raman; Okaya, Kazuki; Matsutani, Koichi; Matsumi, Noriyoshi

    2016-11-01

    Electrocatalytic materials for oxygen reduction reaction, currently dominated by platinum/carbon catalyst is marred by drawbacks such as use of copious amount of Pt and use of “non-green” sacrificial reducing agent (SRA) during its synthesis. A single stroke remedy for these two problems has been achieved through an in-situ aqueous photoreduction void of even trace amounts of SRA with an enhanced activity. Reduction of PtCl62‑ salt to Pt nano particles on carbon substrate was achieved solely using solar spectrum as the source of energy and TiO2 as photocatalyst. Here, we demonstrate that this new procedure of photoreduction, decorates Pt over different types of conducting allotropes with the distribution and the particle size primarily depending on the conductivity of the allotrope. The Pt/C/TiO2 composite unveiled an ORR activity on par to the most efficient Pt based electrocatalyst prepared through the conventional sacrificial reducing agent aided preparation methods.

  8. Electrochemical performance of La2O3/Li2O/TiO2 nano-particle coated cathode material LiFePO4.

    PubMed

    Wang, Hong; Yang, Chi; Liu, Shu-Xin

    2014-09-01

    Cathode material, LiFePO4 was modified by coating with a thin layer of La2O3/Li2O/TiO2 nano-particles for improving its performance for lithium ion batteries. The morphology and structure of the modified cathode material were characterized by powder X-ray diffraction, scanning electron microcopy and AES. The performance of the battery with the modified cathode material, including cycling stability, C-rate discharge was examined. The results show that the battery composed of the coated cathode materials can discharge at a large current density and show stable cycling performance in the range from 2.5 to 4.0 V. The rate of Li ion diffusion increases in the battery with the La2O3/Li2O/TiO2-coated LiFePO4 as a cathode and the coating layer may acts as a faster ion conductor (La(2/3-x)Li(3x)TiO3).

  9. Sacrificial Reducing Agent Free Photo-Generation of Platinum Nano Particle over Carbon/TiO2 for Highly Efficient Oxygen Reduction Reaction

    PubMed Central

    Badam, Rajashekar; Vedarajan, Raman; Okaya, Kazuki; Matsutani, Koichi; Matsumi, Noriyoshi

    2016-01-01

    Electrocatalytic materials for oxygen reduction reaction, currently dominated by platinum/carbon catalyst is marred by drawbacks such as use of copious amount of Pt and use of “non-green” sacrificial reducing agent (SRA) during its synthesis. A single stroke remedy for these two problems has been achieved through an in-situ aqueous photoreduction void of even trace amounts of SRA with an enhanced activity. Reduction of PtCl62− salt to Pt nano particles on carbon substrate was achieved solely using solar spectrum as the source of energy and TiO2 as photocatalyst. Here, we demonstrate that this new procedure of photoreduction, decorates Pt over different types of conducting allotropes with the distribution and the particle size primarily depending on the conductivity of the allotrope. The Pt/C/TiO2 composite unveiled an ORR activity on par to the most efficient Pt based electrocatalyst prepared through the conventional sacrificial reducing agent aided preparation methods. PMID:27845439

  10. Gold nano-particles (AuNPs) carrying anti-EBV-miR-BART7-3p inhibit growth of EBV-positive nasopharyngeal carcinoma

    PubMed Central

    Wang, Jianguo; Lyu, Xiaoming; Chen, Yuxiang; Liu, Jinkun; Cai, Hongbing; Wang, Ying; Li, Xin

    2015-01-01

    Epstein-Barr virus (EBV) infection is a major etiological factor for nasopharyngeal carcinoma (NPC). Several EBV-encoded BART miRNAs have been associated with viral latency, immune escape, cell survival, cell proliferation and apoptosis. Here, we report that EBV-miR-BART7-3p, an EBV-encoded BART miRNA highly expressed in NPC, was correlated with cell-cycle progression in vitro and increased tumor formation in vivo. This viral miRNA stimulated the PTEN/PI3K/Akt pathway and induced c-Myc and c-Jun. Knockdown of PTEN mimicked EBV-miR-BART7-3p-induced tumorigenic phenotype. Based on these results, we conducted a therapeutic experiment by using gold nano-particles (AuNPs) carrying anti-EBV-miR-BART7-3p. Silencing of EBV-miR-BART7-3p reduced tumor growth in animal model. We conclude that EBV-miR-BART7-3p favors carcinogenesis, representing a potential target for miRNA-based therapy. PMID:25691053

  11. Fabrication of dye-sensitized solar cell (DSSC) using different particle sizes of TiO2 deposited via nano-particle deposition system (NPDS).

    PubMed

    Kim, Yang-Hee; Kim, Kwang-Su; Lee, Jin-Woong; Kim, Min-Saeng; Choi, Jung-Oh; Ahn, Sung-Hoon; Lee, Caroline Sunyong

    2012-04-01

    TiO2 layers were fabricated using a nano-particle deposition system (NPDS) on transparent conductive oxide (TCO) glass for dye sensitized solar cells (DSSCs). Conventionally, TiO2 paste for working electrodes has been fabricated using paste type methods. The fabricated paste composed of a mixture of nano-sized TiO2 powders, binders and solutions is then painted on TCO glass. After drying, the TiO2 layer on TCO glass is sintered to make a path for electron transfer. TiO2 layers formed by this paste type method require numerous steps, which can be time consuming. In this study, TiO2 powders were sprayed directly on TCO glass using NPDS in order to simplify the fabrication steps. To improve porosity and produce scattering layers, commercial nanocrystalline TiO, powders with different sizes were alternately deposited. Moreover, powders with different sizes were mixed and deposited on the TCO glass. The results indicate that the DSSCs with a TiO2 layer composed of different particle sizes had better cell performance than the cells assembled with single-sized TiO2 particles. Therefore, this study shows that a dry TiO2 coating process is possible for DSSC fabrication to improve its cell efficiencies, and this method can easily be applied on flexible substrates since NPDS is a room-temperature deposition process.

  12. Detection and differentiation of Salmonella serotypes using Surface Enhanced Raman Scattering (SERS) technique.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surface Enhanced Raman Scattering (SERS) can detect pathogens rapidly and accurately. The metal surface for the SERS spectroscopy was a silver nano-particle encapsulated biopolymer polyvinyl alcohol nano-colloid deposited on a stainless steel plate. Salmonella Typhimurium and Salmonella Enteritidis...

  13. Short-Range Correlations in Magnetite above the Verwey Temperature

    NASA Astrophysics Data System (ADS)

    Bosak, Alexey; Chernyshov, Dmitry; Hoesch, Moritz; Piekarz, Przemysław; Le Tacon, Mathieu; Krisch, Michael; Kozłowski, Andrzej; Oleś, Andrzej M.; Parlinski, Krzysztof

    2014-01-01

    Magnetite, Fe3O4, is the first magnetic material discovered and utilized by mankind in Ancient Greece, yet it still attracts attention due to its puzzling properties. This is largely due to the quest for a full and coherent understanding of the Verwey transition that occurs at TV=124 K and is associated with a drop of electric conductivity and a complex structural phase transition. A recent detailed analysis of the structure, based on single crystal diffraction, suggests that the electron localization pattern contains linear three-Fe-site units, the so-called trimerons. Here, we show that whatever the electron localization pattern is, it partially survives up to room temperature as short-range correlations in the high-temperature cubic phase, easily discernible by diffuse scattering. Additionally, ab initio electronic structure calculations reveal that characteristic features in these diffuse scattering patterns can be correlated with the Fermi surface topology.

  14. Extended release of vitamins from magnetite loaded polyanionic polymeric beads.

    PubMed

    Sonmez, Maria; Verisan, Cristina; Voicu, Georgeta; Ficai, Denisa; Ficai, Anton; Oprea, Alexandra Elena; Vlad, Mihaela; Andronescu, Ecaterina

    2016-08-30

    Here we explore a novel approach of increasing the release duration of folic and ascorbic acid from magnetite entrapped into calcium-alginate beads. Synthesis and characterization of magnetite-vitamins complexes are reported. The magnetite-vitamins complexes were characterized by FT-IR, XRD, SEM, BET and DTA-TG. Also calcium-alginate magnetic beads were prepared by dripping a mixture of sodium alginate with magnetite-vitamins complexes into calcium chloride solution. Extended release profile of the two experimental models was evaluated and quantified by UV-vis.

  15. Evaluation of the sediment remediation potential of magnetite impregnated activated carbons and biochars

    NASA Astrophysics Data System (ADS)

    Werner, David; Han, Zhantao; Karapanagioti, Hrissi

    2014-05-01

    We evaluated the sediment remediation potential of magnetic composite materials synthesized by precipitating magnetite minerals onto activated carbons and biochars. Magnetite impregnation did not reduce the phenanthrene sorption capacity of the activated carbon or biochar component of the composite materials. The phenanthrene sorption capacity of the composite materials correlated with the surface areas of the pristine carbonaceous sorbents. XRD data and mass magnetic susceptibility data indicate that the mineral component of the composites is indeed nearly 100% magnetite. Addition of magnetic activated carbon to River Tyne sediment slurries reduced polycyclic aromatic hydrocarbon availability by more than 90%. After 3 months of mixing, 77% of the added magnetic activated carbon could be recovered with a magnetic rod. Continued monitoring showed that polycyclic aromatic hydrocarbon availability remained low following the magnetic recovery of most of the added sorbent mass. XRD analysis confirmed the presence of magnetite in the recovered sorbent material, with some other mineral phases such as calcite and quartz also being identifiable. Magnetic activated carbon has potential as a recoverable sorbent amendment for the treatment of sediment polluted with hydrophobic organic compounds. Further work will include an evaluation of the long-term magnetic sorbent effectiveness and stability in unmixed sediments under aerobic and anaerobic conditions and regeneration and re-use options for the recovered sorbent materials.

  16. Sorptive uptake of selenium with magnetite and its supported materials onto activated carbon.

    PubMed

    Kwon, Jae H; Wilson, Lee D; Sammynaiken, R

    2015-11-01

    Kinetic and equilibrium uptake studies of selenite in aqueous solution with synthetic magnetite (Mag-P), commercial magnetite (Mag-C), goethite, activated carbon (AC), and a composite material containing 19% magnetite supported on activated carbon (CM-19) were investigated. Kinetic uptake studies used a one-pot setup at pH 5.26 at variable temperature. Sampling of unbound selenite in-situ was achieved with analytical detection by atomic absorbance. The sorptive uptake at equilibrium and kinetic conditions are listed in descending order: goethite>Mag-P>Mag-C>CM-19. Kinetic uptake parameters reveal that Mag-P showed apparent negative values for the activation energy (E(a)) and the enthalpy of activation (ΔH(‡)), in agreement with a multi-step process for the kinetic uptake of selenite. By contrast, Mag-C, CM-19, and goethite showed positive values for E(a) and ΔH(‡). The uptake properties of the various sorbent materials with selenite are in accordance with the formation of inner- and out-sphere complexes. Leaching of iron from the composite material (CM-19) was attenuated due to the stabilizing effect of the magnetite within the pore sites and the surface of AC. Supported iron oxide nanomaterial composites represent a unique sorbent material with tunable uptake properties toward inorganic selenite in aqueous solution.

  17. In situ formation of magnetite reactive barriers in soil for waste stabilization

    DOEpatents

    Moore, Robert C.

    2003-01-01

    Reactive barriers containing magnetite and methods for making magnetite reactive barriers in situ in soil for sequestering soil contaminants including actinides and heavy metals, organic materials, iodine and technetium are disclosed. According to one embodiment, a two-step reagent introduction into soil takes place. In the first step, free oxygen is removed from the soil by separately injecting into the soil aqueous solutions of iron (II) salt, for example FeCl.sub.2, and base, for example NaOH or NH.sub.3 in about a 1:1 volume ratio. Then, in the second step, similar reagents are injected a second time (however, according to about a 1:2 volume ratio, iron to salt) to form magnetite. The magnetite formation is facilitated, in part, due to slow intrusion of oxygen into the soil from the surface. The invention techniques are suited to injection of reagents into soil in proximity to a contamination plume or source allowing in situ formation of the reactive barrier at the location of waste or hazardous material. Mixing of reagents to form. precipitate is mediated and enhanced through movement of reagents in soil as a result of phenomena including capillary action, movement of groundwater, soil washing and reagent injection pressure.

  18. Detection sensitivity of MRI using ultra-small super paramagnetic iron oxide nano-particles (USPIO) in biological tissues.

    PubMed

    Oghabian, M A; Guiti, M; Haddad, P; Gharehaghaji, N; Saber, R; Alam, N R; Malekpour, M; Rafie, B

    2006-01-01

    Today, by injecting iron oxide based nanoparticles (USPIO) as MRI contrast agents, it is possible to study lymphatic system and some specific tumors and their metastasis. The type of surface coating, and coating characteristics of the nanoparticles are important factors for the biological properties of nanoparticles and their destination target. On the other hand, these properties contribute to different signal intensities. This may confine application of all types of USPIO based contrast agents in routine daily experiments. In this study, the ability of detecting these particles having various sizes and coating properties was evaluated for MRI applications. Signal intensity changes after administration of these particles into tissues have been studied and their detection sensitivity was evaluated using a liver phantom and animal model (rat). IO based nanoparticles of various sizes (8-30 nm) functionalized and coated with various surface polymers such as dextran and starch, amine and hydroxide groups, and bear IO particles were used to investigate the signal changes. The optimized pulse sequences for proper demonstration of lymph nodes using these contrast agents were found (T2* FSPGR protocol with fat suppressions). A detection sensitivity of 98% was achieved in most experiments during applying a proper MR protocol. However, the type of surface coating, and coating characteristics such as thickness were shown to be essential factors for MRI signal intensity in both T1 and T2 protocols.

  19. Synthesis of single phase {alpha}-Fe, Fe{sub 3}C and Fe{sub 7}C{sub 3} nano-particles by CO{sub 2} laser pyrolysis technique. Quarterly progress report, January--March, 1992

    SciTech Connect

    Eklund, P.C.; Bi, X.X.

    1992-07-01

    Iron-containing catalysts have been known to be useful in assisting the Fischer-Tropsch (FT) reaction for synthesizing hydrocarbons. However, it has been well recognized that iron catalyst are not stable during the reaction but converted into iron carbides. It is thus important to understand the role of the iron carbides in the catalytic reaction of the FT-synthesis. It has been found difficult to produce iron carbide nano-particles as a single phase, because iron carbide phases are only metastable under 1 atm pressure. Iron carbide bulk particles prepared so far are often contaminated with metallic iron, iron oxides and free carbon. In this study, we investigate the synthesis of iron carbide nano-particles using CO{sub 2} laser pyrolysis technique. We show that this technique is successful in synthesizing {alpha}-Fe, Fe{sub 3}C and Fe{sub 7}C{sub 3} nano-particles in their single phase with sizes in the range of 5--20nm. In particular, we have produced for the first time the Fe{sub 7}C{sub 3} which has been known to exist but unable to be produced as a single phase. Furthermore, it is interesting that Fe{sub 5}C{sub 2} which has carbon and iron ratio between Fe{sub 3}C and Fe{sub 7}C{sub 3}, is not seen in any run of our synthesis.

  20. Enhancement of light harvesting efficiency of silicon solar cell utilizing arrays of poly(methyl methacrylate-co-acrylic acid) nano-spheres and nano-spheres with embedded silver nano-particles

    NASA Astrophysics Data System (ADS)

    Lee, Chee-Leong; Goh, Wee-Sheng; Chee, Swee-Yong; Yik, Lai-Kuan

    2017-02-01

    An array of uniformly distributed monolayer of poly(methyl methacrylate-co-acrylic acid) nano-spheres were deposited onto an amorphous silicon photovoltaic cell utilizing dip coating technique. The electrical characteristics of the coated photovoltaic cell reveal that the nano-spheres with an average diameter size of 101 nm exhibits excellent light harvesting characteristics if compared to the nano-spheres of other sizes. The power conversion efficiency from such integration of the nano-structures (i.e. 3.14% per PV cell) indicates that at least 1.6 times of improvement (or relative enhancement of 57%) can be achieved comparatively to the uncoated photovoltaic cell (i.e. 2% per PV cell). Further increment of the power conversion efficiency of the solar cell has been attained with the incorporation of the silver nano-particles into the nano-spheres of similar average size. With the inclusion of the silver nano-particles into such nano-spheres, the power conversion efficiency of the solar cell has attained 5.57% per PV cell, which is about 2.8 times (or relative enhancement of 179%) if compared to the uncoated samples. Hence, this novel and controllable technique of fabricating omnidirectional light-harvesting nano-spheres with embedded silver nano-particles will indubitably be beneficial to various types of optoelectronic devices.

  1. Biofouling inhibition and enhancing performance of microbial fuel cell using silver nano-particles as fungicide and cathode catalyst.

    PubMed

    Noori, Md T; Jain, Sumat C; Ghangrekar, M M; Mukherjee, C K

    2016-11-01

    Morphological analysis of biofouling developed on cathode surface in an air-cathode microbial fuel cell (MFC) was performed. For sustaining power production and enhancing Coulombic efficiency (CE) of MFC, studies were conducted to inhibit cathode biofouling using different loadings of silver nanoparticles (Ag-NPs) with 5% and 10% Ag in carbon black powder. In MFC without using Ag-NPs in cathode (MFC-C), cathode biofouling increased the charge transfer resistance (Rct) from 1710Ω.cm(2) to 2409Ω.cm(2), and reduced CE by 32%; whereas in MFC with 10% Ag in cathode Rct increased by only 5%. Power density of 7.9±0.5W/m(3) in MFC using 5% Ag and 9.8±0.3W/m(3) in MFC using 10% Ag in cathode was 4.6 and 5.7-folds higher than MFC-C. These results suggest that the Ag-NPs effectively inhibit the fungal biofouling on cathode surface of MFCs and enhanced the power recovery and CE by improving cathode kinetics.

  2. Performance of iron nano particles and bimetallic Ni/Fe nanoparticles in removal of amoxicillin trihydrate from synthetic wastewater.

    PubMed

    Yazdanbakhsh, Ahmad Reza; Daraei, Hasti; Rafiee, Mohamad; Kamali, Hosein

    2016-01-01

    In the present study, the degradation of amoxicillin trihydrate (AMT), using synthesized nanoscale zero-valent iron (nZVI) and bimetallic Fe and Ni nanoparticles stabilized with chitosan (Cs-Fe/Ni), in water was investigated. A central composite design combined with response surface methodology and optimization was utilized for maximizing the AMT reduction by the nanoparticles-water system. The importance of the various variables and their interactions were analyzed using analysis of variance and t-test. The effects of independent parameters were tested and the results showed that the initial concentration of AMT, pH, and nanoparticles dosage were all significant factors. Field-emission scanning electron microscopy images indicated that chitosan acts as a stabilizer preventing the agglomeration of nanoparticles. Also, chitosan and Ni increased the specific surface area of Cs-Fe/Ni. X-ray diffraction confirmed the existence of Fe(0) in fresh samples and the presence of Fe(II) and Fe(III) after the reaction with AMT. This study demonstrates that the nZVI technology could be a promising approach for antibiotic wastewater treatment.

  3. Characterization of bismuth selenide (Bi2Se3) thin films obtained by evaporating the hydrothermally synthesised nano-particles

    NASA Astrophysics Data System (ADS)

    Indirajith, R.; Rajalakshmi, M.; Gopalakrishnan, R.; Ramamurthi, K.

    2016-03-01

    Bismuth selenide (Bi2Se3) was synthesized by hydrothermal method at 200 °C and confirmed by powder X-ray diffraction (XRD) studies. The synthesized material was utilized to deposit bismuth selenide thin films at various substrate temperatures (Room Temperature-RT, 150 °C, 250 °C, 350 °C and 450 °C) by electron beam evaporation technique. XRD study confirmed the polycrystalline nature of the deposited Bi2Se3films. Optical transmittance spectra showed that the deposited (at RT) films acquire relatively high average transmittance of 60%in near infrared region (1500-2500 nm). An indirect allowed optical band gap calculated from the absorption edge for the deposited films is ranging from 0.62 to 0.8 eV. Scanning electron and atomic force microscopy analyses reveal the formation of nano-scale sized particles on the surface and that the nature of surface microstructures is influenced by the substrate temperature. Hall measurements showed improved electrical properties, for the films deposited at 350 °C which possess 2.8 times the mobility and 0.9 times the resistivity of the films deposited at RT.

  4. The effect of micro/nano particle size on the thermal, tribological properties and the performances of coated composite tools

    NASA Astrophysics Data System (ADS)

    Nakkiew, Wasawat

    In metal cutting, selecting an appropriate cutting tool is a critical factor for obtaining a good surface integrity on the machined surface and achieving high efficiency of the process. Tribological and thermal properties such as coefficient of friction and thermal conductivity of the cutting tool are important in determining mechanical and thermal fields which contribute to both the surface integrity of the machined part and the efficiency of the process. In the case of coated composite tools, size of dispersed particulates is considered as an important factor in determining both tribological and thermal properties of the cutting tool. However, very few studies provide fundamental understanding of the relationships between the particulate size and other properties in composite tools. The main objective of this research is to develop a new scientific methodology of determining and analyzing important fundamental variables for high performance cutting tool design and optimization. The first part of this research investigates the effect of dispersed particulate sizes on thermal conductivity of coated composite tools. Then, a statistical model is used for determining a relationship of coefficient of friction as a function of thermal conductivity and surface roughness and hardness of the workpiece. Then, a fully coupled thermalstress finite element model of orthogonal cutting is constructed for doing sensitivity analysis of the effects of thermal conductivity and coefficient of friction on mechanical and thermal fields. Results show stress and temperature distributions as affected by different values of thermal conductivities and coefficients of frictions. The results also show residual stress at different depths on the machined surface, generated from cutting tools with different thermal conductivities and coefficients of frictions. Since tool life is a criterion for evaluating a cutting tool's performance, a statistical model is developed for determining the

  5. Viscosity studies of water based magnetite nanofluids

    NASA Astrophysics Data System (ADS)

    Anu, K.; Hemalatha, J.

    2016-05-01

    Magnetite nanofluids of various concentrations have been synthesized through co-precipitation method. The structural and topographical studies made with the X-Ray Diffractometer and Atomic Force Microscope are presented in this paper. The density and viscosity studies for the ferrofluids of various concentrations have been made at room temperature. The experimental viscosities are compared with theoretical values obtained from Einstein, Batchelor and Wang models. An attempt to modify the Rosensweig model is made and the modified Rosensweig equation is reported. In addition, new empirical correlation is also proposed for predicting viscosity of ferrofluid at various concentrations.

  6. Design, Characterization and Application of Biocompatible Micro- and Nano-Particles for Dynamic X-ray Visual Imaging

    NASA Astrophysics Data System (ADS)

    Ahn, Sungsook; Jung, Sung Yong; Lee, Sang Joon

    2010-03-01

    For a dynamic X-ray visual imaging, contrast agents in particle forms are developed in micro- and nano-scales. First, water- soluble contrast agents are encapsulated into biocompatible polymeric microparticles. The fabricated polymeric microparticles are controlled in terms of the size, degree of crosslinking and encapsulation efficiency of the X-ray contrast agent. Second, gold is designed into functionalized nanoparticles. Properly controlled aggregates or encapsulated into human red blood cell (RBC), the surface modified gold nanoparticles are used as excellent X-ray contrast agent. The behaviors of the particles in the solution state are described by hydrodynamic size (DH) and zeta-potential (?-potential). The microscopic structures of the gold nanoparticle aggregates are determined by scanning electron microscopy (SEM) and zone-plate X-ray microscopy. The designed particulate biocompatible tracers are successfully used as excellent X-ray imaging tracers which enable the dynamic study in various biological fluid flows.

  7. Comparing gold nano-particle enhanced radiotherapy with protons, megavoltage photons and kilovoltage photons: a Monte Carlo simulation.

    PubMed

    Lin, Yuting; McMahon, Stephen J; Scarpelli, Matthew; Paganetti, Harald; Schuemann, Jan

    2014-12-21

    Gold nanoparticles (GNPs) have shown potential to be used as a radiosensitizer for radiation therapy. Despite extensive research activity to study GNP radiosensitization using photon beams, only a few studies have been carried out using proton beams. In this work Monte Carlo simulations were used to assess the dose enhancement of GNPs for proton therapy. The enhancement effect was compared between a clinical proton spectrum, a clinical 6 MV photon spectrum, and a kilovoltage photon source similar to those used in many radiobiology lab settings. We showed that the mechanism by which GNPs can lead to dose enhancements in radiation therapy differs when comparing photon and proton radiation. The GNP dose enhancement using protons can be up to 14 and is independent of proton energy, while the dose enhancement is highly dependent on the photon energy used. For the same amount of energy absorbed in the GNP, interactions with protons, kVp photons and MV photons produce similar doses within several nanometers of the GNP surface, and differences are below 15% for the first 10 nm. However, secondary electrons produced by kilovoltage photons have the longest range in water as compared to protons and MV photons, e.g. they cause a dose enhancement 20 times higher than the one caused by protons 10 μm away from the GNP surface. We conclude that GNPs have the potential to enhance radiation therapy depending on the type of radiation source. Proton therapy can be enhanced significantly only if the GNPs are in close proximity to the biological target.

  8. Comparing gold nano-particle enhanced radiotherapy with protons, megavoltage photons and kilovoltage photons: a Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Lin, Yuting; McMahon, Stephen J.; Scarpelli, Matthew; Paganetti, Harald; Schuemann, Jan

    2014-12-01

    Gold nanoparticles (GNPs) have shown potential to be used as a radiosensitizer for radiation therapy. Despite extensive research activity to study GNP radiosensitization using photon beams, only a few studies have been carried out using proton beams. In this work Monte Carlo simulations were used to assess the dose enhancement of GNPs for proton therapy. The enhancement effect was compared between a clinical proton spectrum, a clinical 6 MV photon spectrum, and a kilovoltage photon source similar to those used in many radiobiology lab settings. We showed that the mechanism by which GNPs can lead to dose enhancements in radiation therapy differs when comparing photon and proton radiation. The GNP dose enhancement using protons can be up to 14 and is independent of proton energy, while the dose enhancement is highly dependent on the photon energy used. For the same amount of energy absorbed in the GNP, interactions with protons, kVp photons and MV photons produce similar doses within several nanometers of the GNP surface, and differences are below 15% for the first 10 nm. However, secondary electrons produced by kilovoltage photons have the longest range in water as compared to protons and MV photons, e.g. they cause a dose enhancement 20 times higher than the one caused by protons 10 μm away from the GNP surface. We conclude that GNPs have the potential to enhance radiation therapy depending on the type of radiation source. Proton therapy can be enhanced significantly only if the GNPs are in close proximity to the biological target.

  9. The contribution of vanadium and titanium on improving methylene blue decolorization through heterogeneous UV-Fenton reaction catalyzed by their co-doped magnetite.

    PubMed

    Liang, Xiaoliang; Zhong, Yuanhong; Zhu, Sanyuan; Ma, Lingya; Yuan, Peng; Zhu, Jianxi; He, Hongping; Jiang, Zheng

    2012-01-15

    This study investigated the methylene blue (MB) decolorization through heterogeneous UV-Fenton reaction catalyzed by V-Ti co-doped magnetites, with emphasis on comparing the contribution of V and Ti cations on improving the adsorption and catalytic activity of magnetite. In the well crystallized spinel structure, both Ti(4+) and V(3+) occupied the octahedral sites. Ti(4+) showed a more obvious effect on increasing specific surface area and superficial hydroxyl amount than V(3+) did, resulting in a significant improvement of the adsorption ability of magnetite to MB. The UV introduction greatly accelerated MB degradation. And magnetite with more Ti and less V displayed better catalytic activity in MB degradation through heterogeneous UV-Fenton reaction. The transformation of degradation products and individual contribution from vanadium and titanium on improving adsorption and catalytic activity of magnetite were also investigated. These new insights are of high importance for well understanding the interface interaction between contaminants and metal doped magnetites, and the environmental application of natural and synthetic magnetites.

  10. A first test of the hypothesis of biogenic magnetite-based heterogeneous ice-crystal nucleation in cryopreservation.

    PubMed

    Kobayashi, Atsuko; Golash, Harry N; Kirschvink, Joseph L

    2016-06-01

    An outstanding biophysical puzzle is focused on the apparent ability of weak, extremely low-frequency oscillating magnetic fields to enhance cryopreservation of many biological tissues. A recent theory holds that these weak magnetic fields could be inhibiting ice-crystal nucleation on the nanocrystals of biological magnetite (Fe3O4, an inverse cubic spinel) that are present in many plant and animal tissues by causing them to oscillate. In this theory, magnetically-induced mechanical oscillations disrupt the ability of water molecules to nucleate on the surface of the magnetite nanocrystals. However, the ability of the magnetite crystal lattice to serve as a template for heterogeneous ice crystal nucleation is as yet unknown, particularly for particles in the 10-100 nm size range. Here we report that the addition of trace-amounts of finely-dispersed magnetite into ultrapure water samples reduces strongly the incidence of supercooling, as measured in experiments conducted using a controlled freezing apparatus with multiple thermocouples. SQUID magnetometry was used to quantify nanogram levels of magnetite in the water samples. We also report a relationship between the volume change of ice, and the degree of supercooling, that may indicate lower degassing during the crystallization of supercooled water. In addition to supporting the role of ice-crystal nucleation by biogenic magnetite in many tissues, magnetite nanocrystals could provide inexpensive, non-toxic, and non-pathogenic ice nucleating agents needed in a variety of industrial processes, as well as influencing the dynamics of ice crystal nucleation in many natural environments.

  11. Magnetic Dinner Salads: The Role of Biogenic Magnetite in Cryopreservation for Common Food Plants

    NASA Astrophysics Data System (ADS)

    Chaffee, T. M.; Kirschvink, J. L.; Kobayashi, A. K.

    2015-12-01

    Biogenically-precipitated magnetite has been found in organisms ranging from Bacteria, single-celled protists, and many of the animal phyla, where its major function is navigation and magnetoreception. To date there is but a single report of biogenic magnetite in plants (essentially, magnetoferritin), and that is in common grass (Festuca species, from Gajdardziska-Josifovska et. al. doi:10.1127/0935-1221/2001/0013/0863). Recent developments in cryopreservation suggest that ~ 1 mT, ~ 10 Hz oscillating magnetic fields can drastically reduce ice nucleation during freezing, promote supercooling, and minimize cellular damage in living tissues (e.g., Kaku et al., doi: 10.1016/j.cryobiol.2012.02.001). Kobayashi & Kirschvink (2014, doi:10.1016/j.cryobiol.2013.12.002) suggest that biogenic magnetite crystals could be the nucleating site for damaging ice crystals, and that they would be driven magneto-mechanically to rotate in those oscillating fields which could inhibit the ice crystal nucleation process. This prompted our investigation into the magnetite content of ordinary fruit and vegetable food products, as knowledge of the natural levels of biogenic magnetite in the human food supply could guide the selection of which foods might work for this type of cryopreservation. Our study involved a range of common foods including avocados, bananas, garlic, and apples. Samples were prepared in a clean lab environment kept free of contaminant particles, and subjected to a variety of standard rock-magnetic tests including IRM and ARM acquisition, and the corresponding Af demagnetization, on a standard 2G™ SRM. Results are consistent with moderately interacting single-domain magnetite (see figure), with moderate inter-particle interaction effects. Typical magnetite concentrations in these samples are in the range of .1 to 1 ng/g for room temperature samples, increasing to the range of 1-10 ng/g when measured frozen (to inhibit thermal rotation of small particles and clumps). If

  12. Infra Red Dye and Endostar Loaded Poly Lactic Acid Nano Particles as a Novel Theranostic Nanomedicine for Breast Cancer.

    PubMed

    Zhang, Qian; Du, Yang; Jing, Lijia; Liang, Xiaolong; Li, Yaqian; Li, Xiaofeng; Dai, Zhifei; Tian, Jie

    2016-03-01

    Endostar, a novel recombinant human endostatin, has been proven to inhibit tumor angiogenesis and is utilized as an anticancer drug. While free drugs can display limited efficacy, nanoscaled anticancer drugs have been fabricated and proven to possess superior therapeutic effects. Poly(lactic acid) (PLA) is a FDA-approved biomaterial displaying excellent biocompatibility and low toxicity. In this study, Endostar-loaded PLA nanoparticles (EPNPs) were first prepared, and a near-infrared (NIR) dye, IRDye 800CW, was conjugated to the surface for detecting nanoparticle biodistribution through fluorescence molecular imaging (FMI) using an orthotopic breast tumor mouse model. The antitumor efficacy of EPNPs was examined using bioluminescence imaging (BLI) and immunohistology. To further improve the antitumor effects, we combined EPNPs with zoledronic acid monohydrate (ZA), which is known to decrease the tumor-associated macrophages (TAM) and inhibit tumor progression. We found that EPNPs decreased human umbilical vein endothelial cell (HUVEC) viability by inhibiting tumor growth gene expression more significantly than free Endostar in vitro. In vivo, EPNPs displayed better tumor growth inhibitory effects compared with free Endostar, and the combination of EPNPs with ZA exhibited more significant antitumor effects. As confirmed by CD31 and CD11b immunohistochemistry, the combination of EPNPs and ZA showed synergistic effects in reducing tumor angiogenesis and TAM accumulation in tumor regions. Taken together, this study presents a novel and effective form of nanoscaled Endostar for the treatment of breast cancer that displays synergistic antitumor effects in combination with ZA.

  13. Behavior of a nano-particle and a polymer molecule in a nano-scale four-roll mill

    NASA Astrophysics Data System (ADS)

    Vo, Minh; Papavassiliou, Dimitrios

    2016-11-01

    The four-roll mill device could be used to create a mixed flow from purely extensional stresses to completely rotational through the proper selection of speed and direction of each of the four cylindrical rollers. Considerable research has been done with this device for macroscale rheological studies.. In our study, the dissipative particle dynamics (DPD) method was employed to investigate the behavior of a nano-sphere and a polymer molecule in different conditions within a four-roll mill device. Hydrophilic properties of each roll were generated by adjusting interaction parameters and using bounce back boundary condition at the solid surface. All simulations were run up to 4x106 time steps at room temperature using the open source LAMMPS package. After the flow in the system reached equilibrium, a nano-sphere and then a polymer chain were released at the center of the simulation box. Their trajectories were recorded at different shear rate conditions. The propagation of nanosphere in different rotational flow will be discussed. Additionally, the deformation of polymer chains will be compared to that in a simple shear flow.

  14. Direct and dry micro-patterning of nano-particles by electrospray deposition through a micro-stencil mask

    NASA Astrophysics Data System (ADS)

    Kim, J.-W.; Yamagata, Y.; Kim, B. J.; Higuchi, T.

    2009-02-01

    A new micro-pattern formation method for thin films of organic or bio-macromolecules is proposed. The method combines an electrospray deposition process with a micro-fabricated stencil mask made of a silicon nitride membrane. The highest resolution of 2 µm line and space is possible using 50 nm fluorescent latex beads. The deposited nano-structure consists of clusters of particles ranging from 100 to 200 nm, which indicates that nanometer resolution is potentially achievable. The surface roughness of the deposit is about 3.6 nm on average, and thickness uniformity is about 10 nm with 76 nm film thickness over 72 µm. Size uniformity of the 5 µm dots reaches 5.2% in the coefficient of variation (CV) value. These results indicate that the resolution and uniformity of the proposed method are high. In addition, the charged particles on the micro stencil mask of electrical insulation are proved to induce a focusing effect, which suggests that the size of the deposited pattern can be smaller than the mask aperture size.

  15. Green Synthesis of Silver Nano-particles by Macrococcus bovicus and Its Immobilization onto Montmorillonite Clay for Antimicrobial Functionality.

    PubMed

    Abdel-Aziz, Mohamed S; Abou-El-Sherbini, Khaled S; Hamzawy, Esmat M A; Amr, Mohey H A; El-Dafrawy, Shady

    2015-08-01

    Macrococcus bovicus was locally isolated from soil and used in the green synthesis of nano-scaling silver (NSAg). It was immobilized on a sodic-montmorillonite clay (MMT1) and cetyltrimethylammonium bromide-modified montmorillonite (MMT2) which was also calcined at 300 °C (MMT3). The NSAg clays were characterized by X-ray fluorescence, Fourier transform infrared spectra, X-ray diffractometry, surface area measurement, UV-Vis spectrometry, scanning electron microscope, transmission electron microscope and thermogravimetric analysis. NSAg was confirmed to be included in the interparticular cavities of the clay sheets and its mechanical stability was evidenced. The antimicrobial activity of the NSAg-modified clays was investigated against Staphylococcus aureus, Escherichia coli and Candida albicans using the cup plate and the plate count techniques. The antimicrobial activity of the NSAg clays was confirmed and attributed to the caging of NSAg in MMT cavities. MMT3 was found to inhibit the microbial growth to as high as 65 % as observed from the plate count method. Graphical Abstract Scheme of the biosynthesis of nano-scaling Ag and its immobilization and antimicrobial application.

  16. Hyaluronan based porous nano-particles enriched with growth factors for the treatment of ulcers: a placebo-controlled study.

    PubMed

    Zavan, B; Vindigni, V; Vezzù, K; Zorzato, G; Luni, C; Abatangelo, G; Elvassore, N; Cortivo, R

    2009-01-01

    The present study describes the production of hyaluronan based porous microparticles by a semi-continuous gas anti-solvent (GAS) precipitation process to be used as a growth factor delivery system for in vivo treatment of ulcers. Operative process conditions, such as pressure, nozzle diameter and HYAFF11 solution concentrations, were adjusted to optimize particle production in terms of morphology and size. Scanning electron microscopy (SEM) and light scattering demonstrated that porous nano-structured particles with a size of 300 and 900 nm had a high specific surface suitable for absorption of growth factors from the aqueous environment within the polymeric matrix. Water acted as a plasticizer, enhancing growth factor absorption. Water contents within the HYAFF11 matrix were analyzed by differential scanning calorimetry (DSC). The absorption process was developed using fluorescence dyes and growth factors. Immunohistochemical analysis confirmed the high efficiency of absorption of growth factor and a mathematical model was generated to quantify and qualify the in vitro kinetics of growth factor release within the polymeric matrix. In vivo experiments were performed with the aim to optimize timed and focal release of PDGF to promote optimal tissue repair and regeneration of full-thickness wounds.

  17. The I-Xe Age of Orgueil Magnetite: New Results

    NASA Technical Reports Server (NTRS)

    Pravdivtseva, O. V.; Hohenberg, C. M.; Meshik, A. P.

    2003-01-01

    I-Xe ages of Murchison and Orgueil magnetites were reported to be the oldest [1] and interpreted as the condensation time of the solar nebula. More recent measurements, conducted on a highly magnetic separate from Orgueil (but not pure magnetite), gave much younger I-Xe ages [2]. We have since performed new studies on two pure separates of Orgueil magnetite, confirming the later closing time of the I-Xe system in this mineral phase. In the previous work of Lewis and Anders [1] special attention was paid to the purity of the analyzed material. It was shown, that the trapped Xe resided mostly in hydrated silicates and the radiogenic 129Xe in magnetite [3]. Therefore, Orgueil was finely ground and stirred with a saturated LiCl solution for 8 days at 60 C to remove the silicate-magnetite intergrowth. Although this procedure yields magnetic fractions that are at least 90% pure [1], it could potentially contaminate the magnetite with iodine and produce noncorrelated 128Xe and spurious I-Xe ages. To avoid this possibility, in our first work with Orgueil we deliberately omitted separation in LiCl solution. Instead, the meteorite was ground into a fine powder and the highly magnetic fraction was separated with a hand magnet and was confirmed to be largely magnetite [2]. The new work, reported here, was done in order to confirm our previous results and investigate the effects of the LiCl treatment on the I-Xe system in magnetite.

  18. Lymphatic mapping and sentinel node location with magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Jung, Chu W.; Rogers, James M.; Groman, Ernest V.

    1999-04-01

    Subcutaneously administered magnetite nanoparticles were used to locate sentinel lymph nodes in normal rats. Nanoparticles sequestered in brachial and axillary lymph nodes produced magnetic susceptibility artifacts in gradient recall echo magnetic resonance images. The artifact sizes enabled the determination of nanoparticle nodal uptake rates and lymphatic drainage patterns. These studies were confirmed by use of 59Fe labeled magnetite nanoparticles.

  19. Magnetic process for removing heavy metals from water employing magnetites

    DOEpatents

    Prenger, F. Coyne; Hill, Dallas D.; Padilla, Dennis D.; Wingo, Robert M.; Worl, Laura A.; Johnson, Michael D.

    2003-07-22

    A process for removing heavy metals from water is provided. The process includes the steps of introducing magnetite to a quantity of water containing heavy metal. The magnetite is mixed with the water such that at least a portion of, and preferably the majority of, the heavy metal in the water is bound to the magnetite. Once this occurs the magnetite and absorbed metal is removed from the water by application of a magnetic field. In most applications the process is achieved by flowing the water through a solid magnetized matrix, such as steel wool, such that the magnetite magnetically binds to the solid matrix. The magnetized matrix preferably has remnant magnetism, but may also be subject to an externally applied magnetic field. Once the magnetite and associated heavy metal is bound to the matrix, it can be removed and disposed of, such as by reverse water or air and water flow through the matrix. The magnetite may be formed in-situ by the addition of the necessary quantities of Fe(II) and Fe(III) ions, or pre-formed magnetite may be added, or a combination of seed and in-situ formation may be used. The invention also relates to an apparatus for performing the removal of heavy metals from water using the process outlined above.

  20. Magnetic process for removing heavy metals from water employing magnetites

    DOEpatents

    Prenger, F. Coyne; Hill, Dallas D.

    2006-12-26

    A process for removing heavy metals from water is provided. The process includes the steps of introducing magnetite to a quantity of water containing heavy metal. The magnetite is mixed with the water such that at least a portion of, and preferably the majority of, the heavy metal in the water is bound to the magnetite. Once this occurs the magnetite and absorbed metal is removed from the water by application of a magnetic field. In most applications the process is achieved by flowing the water through a solid magnetized matrix, such as steel wool, such that the magnetite magnetically binds to the solid matrix. The magnetized matrix preferably has remnant magnetism, but may also be subject to an externally applied magnetic field. Once the magnetite and associated heavy metal is bound to the matrix, it can be removed and disposed of, such as by reverse water or air and water flow through the matrix. The magnetite may be formed in-situ by the addition of the necessary quantities of Fe(II) and Fe(III) ions, or pre-formed magnetite may be added, or a combination of seed and in-situ formation may be used. The invention also relates to an apparatus for performing the removal of heavy metals from water using the process outlined above.

  1. Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

    NASA Astrophysics Data System (ADS)

    Beck, Mihály T.; Bertóti, Imre; Mohai, Miklós; Németh, Péter; Jakab, Emma; Szabó, László; Szépvölgyi, János

    2017-02-01

    In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN)2. XPS and TEM show that in heat treatment at 450 °C for 1 h in Ar, loss of nitrogen and carbon occurs and small, 5-30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60-200 nm size and well faceted Au particles develop together with a fibrous (CN)n polymer phase, and the Au crystallites are covered by a 3-5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4-20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar+ ion bombardment with 2500 eV energy, 5-30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications.

  2. Incorporation of photosenzitizer hypericin into synthetic lipid-based nano-particles for drug delivery and large unilamellar vesicles with different content of cholesterol

    NASA Astrophysics Data System (ADS)

    Joniova, Jaroslava; Blascakova, Ludmila; Jancura, Daniel; Nadova, Zuzana; Sureau, Franck; Miskovsky, Pavol

    2014-08-01

    Low-density lipoproteins (LDL) and high-density lipoproteins (HDL) are attractive natural occurring vehicles for drug delivery and targeting to cancer tissues. The capacity of both types of the lipoproteins to bind hydrophobic drugs and their functionality as drug carriers have been examined in several studies and it has been also shown that mixing of anticancer drugs with LDL or HDL before administration led to an increase of cytotoxic effects of the drugs in the comparison when the drugs were administered alone. However, a difficult isolation of the lipoproteins in large quantity from a biological organism as well as a variability of the composition and size of these molecules makes practical application of LDL and HDL as drug delivery systems quite complicated. Synthetic LDL and HDL and large unilamellar vesicles (LUV) are potentially suitable candidates to substitute the native lipoproteins for targeted and effective drug delivery. In this work, we have studied process of an association of potent photosensitizer hypericin (Hyp) with synthetic lipid-based nano-particles (sLNP) and large unilamellar vesicles (LUV) containing various amount of cholesterol. Cholesterol is one of the main components of both LDL and HDL particles and its presence in biological membranes is known to be a determining factor for membrane properties. It was found that the behavior of Hyp incorporation into sLNP particles with diameter ca ~ 90 nm is qualitatively very similar to that of Hyp incorporation into LDL (diameter ca. 22 nm) and these particles are able to enter U-87 MG cells by endocytosis. The presence of cholesterol in LUV influences the capacity of these vesicles to incorporate Hyp into their structure.

  3. A novel electrochemical biosensor based on the hemin-graphene nano-sheets and gold nano-particles hybrid film for the analysis of hydrogen peroxide.

    PubMed

    Song, Haiyan; Ni, Yongnian; Kokot, Serge

    2013-07-25

    Hydrogen peroxide is an important analyte in biochemical, industrial and environmental systems. Therefore, development of novel rapid and sensitive analytical methods is useful. In this work, a hemin-graphene nano-sheets (H-GNs)/gold nano-particles (AuNPs) electrochemical biosensor for the detection of hydrogen peroxide (H2O2) was researched and developed; it was constructed by consecutive, selective modification of the GCE electrode. Performance of the H-GNs/AuNPs/GCE was investigated by chronoamperometry, and AFM measurements suggested that the graphene flakes thickness was ~1.3 nm and that of H-GNs was ~1.8 nm, which ultimately indicated that each hemin layer was ~0.25 nm. This biosensor exhibited significantly better electrocatalytic activity for the reduction of hydrogen peroxide in comparison with the simpler AuNPs/GCE and H-GNs/GCE; it also displayed a linear response for the reduction of H2O2 in the range of 0.3 μM to 1.8 mM with a detection limit of 0.11μM (SN(-1)=3), high sensitivity of 2774.8 μA mM(-1) cm(-2), and a rapid response, which reached 95% of the steady state condition within 5s. In addition, the biosensor was unaffected by many interfering substances, and was stable over time. Thus, it was demonstrated that this biosensor was potentially suitable for H2O2 analysis in many types of sample.

  4. Nano-particle vaccination combined with TLR-7 and -9 ligands triggers memory and effector CD8⁺ T-cell responses in melanoma patients.

    PubMed

    Goldinger, Simone M; Dummer, Reinhard; Baumgaertner, Petra; Mihic-Probst, Daniela; Schwarz, Katrin; Hammann-Haenni, Anya; Willers, Joerg; Geldhof, Christine; Prior, John O; Kündig, Thomas M; Michielin, Olivier; Bachmann, Martin F; Speiser, Daniel E

    2012-11-01

    Optimal vaccine strategies must be identified for improving T-cell vaccination against infectious and malignant diseases. MelQbG10 is a virus-like nano-particle loaded with A-type CpG-oligonucleotides (CpG-ODN) and coupled to peptide(16-35) derived from Melan-A/MART-1. In this phase IIa clinical study, four groups of stage III-IV melanoma patients were vaccinated with MelQbG10, given (i) with IFA (Montanide) s.c.; (ii) with IFA s.c. and topical Imiquimod; (iii) i.d. with topical Imiquimod; or (iv) as intralymph node injection. In total, 16/21 (76%) patients generated ex vivo detectable Melan-A/MART-1-specific T-cell responses. T-cell frequencies were significantly higher when IFA was used as adjuvant, resulting in detectable T-cell responses in all (11/11) patients, with predominant generation of effector-memory-phenotype cells. In turn, Imiquimod induced higher proportions of central-memory-phenotype cells and increased percentages of CD127(+) (IL-7R) T cells. Direct injection of MelQbG10 into lymph nodes resulted in lower T-cell frequencies, associated with lower proportions of memory and effector-phenotype T cells. Swelling of vaccine site draining lymph nodes, and increased glucose uptake at PET/CT was observed in 13/15 (87%) of evaluable patients, reflecting vaccine triggered immune reactions in lymph nodes. We conclude that the simultaneous use of both Imiquimod and CpG-ODN induced combined memory and effector CD8(+) T-cell responses.

  5. Micromagnetism in (001) magnetite by spin-polarized low-energy electron microscopy.

    PubMed

    de la Figuera, Juan; Vergara, Lucía; N'diaye, Alpha T; Quesada, Adrian; Schmid, Andreas K

    2013-07-01

    Spin-polarized low-energy electron microscopy was used to image a magnetite crystal with (001) surface orientation. Sets of spin-dependent images of magnetic domain patterns observed in this surface were used to map the direction of the magnetization vector with high spatial and angular resolution. We find that domains are magnetized along the surface <110> directions, and domain wall structures include 90° and 180° walls. A type of unusually curved domain walls are interpreted as Néel-capped surface terminations of 180° Bloch walls.

  6. Zinc and Arsenic Immobilization and Magnetite Formation Upon Maghemite Reduction by Shewanella putrefaciens ATCC 8071

    NASA Astrophysics Data System (ADS)

    Cismasu, C.; Ona-Nguema, G.; Bonnin, D.; Menguy, N.; Brown, G. E.

    2007-12-01

    Dissimilatory reduction of ferric iron oxides is recognized as an important component of the iron biogeochemical cycle, causing the dissolution of iron oxide minerals and the possible formation of Fe(II)-bearing minerals such as magnetite, green rusts, siderite, etc. These mineralogical transformations affect the mobility of surface- associated toxic metal(loid)s, which may be released into solution, adsorbed, or incorporated into newly formed minerals. Maghemite (γ-Fe2O3) is an iron oxide mineral that is found in certain tropical soils and as isolated deposits in more temperate regions. In these settings, maghemite may play an important role in the biogeochemical cycling of iron and of surface-associated trace metal(loids). However, the reduction of maghemite by iron-respiring bacteria, the impact of reductive dissolution on the release of associated contaminants, and the nature of biogenic Fe(II)-containing reaction products are not well documented. In the present study, we incubated samples of pure maghemite and As(V)- and Zn-adsorbed maghemite with an iron reducing bacterium, Shewanella putrefaciens strain ATCC 8071, in a batch system under anoxic conditions. As a result of Fe(III) bioreduction, all mineral suspensions turned from brown to black during the first hour of incubation, indicating the onset of magnetite formation. The presence of this mineral was confirmed by transmission Mössbauer spectroscopy at room temperature, which showed the formation of an almost stoichiometric magnetite. High-resolution transmission electron microscopy images indicate that the parent maghemite and the biogenic magnetite particles are octahedral in shape and of similar size (5 to 20 nm). The presence of 50 mg/L adsorbed Zn(II) did not affect the initial rate of iron reduction with respect to the Zn-free maghemite sample (0.62 mM Fe(II)/h and 0.66 mM Fe(II)/h, respectively). However, adsorption of 50 and 100 mg/L As(V) on maghemite decreased the initial iron reduction rate

  7. Effects of acido-basic support properties on the catalytic hydrogenation of acetylene on gold nano-particles

    NASA Astrophysics Data System (ADS)

    Manda, Abdullah Ahmed

    Metallic gold nanoparticles supported on gamma-Al2O 3 and magnesia-alumina mixed oxide, with different magnesia content have been prepared by sol-gel method and characterized by different techniques (inductive coupled plasma-mass spectroscopy (ICP-MS), XRD, BET surface area analysis, transmission electron microscopy (TEM), CO2 and NH 3 temperature programmed desorption (TPD), H2 temperature programmed reduction (TPR) and FTIR of adsorbed CO2). Such systems were found to produce catalysts with controllable acidity, varying from catalyst possessing large density of acidic and low density of basic sites, others with acidic and basic sites of equal strength and density, and others with large basic and low acid sites densities, respectively. The catalytic assessment of the generated acidity was carried out using 2-propanol decomposition as a test reaction. The results obtained indicate that the presence of magnesia and reduced gold nanopartilces has imparted the catalysts, 1%Au/4%Mg-Al 2O3 and 1%Au/8%Mg-Al2O3, with significant base-catalytic properties. Acetylene hydrogenation and formation of coke deposits were investigated on a gold catalyst supported on gamma-Al2O3 and gold supported on alumina-magnisia mixed oxide with different gold content; 1%Au/gamma-Al 2O3, 1%Au/15%Mg-Al2O3, 2%Au/15%Mg-Al 2O3 and 4%Au/15%Mg-Al2O3. The effect of the H2/C2H2 ratio was studied over a range of values. The catalytic activity and selectivity towards ethylene and other products were investigated at different reaction temperatures. Acetylene hydrogenation was investigated in the presence and absence of ethylene in stream. It is investigated that the adsorption of the triple bond is preferred over the double bond and during selective catalytic (SCR) of C2H2 the two hydrocarbons do not compete for the same adsorption sites. The deactivation of catalysts was studied by temperature programmed oxidation (TPO). Higher content of coke over 1%Au/Al2O3 catalyst was investigated in contrast to

  8. Modifying magnetic properties of ultra-thin magnetite films by growth on Fe pre-covered MgO(001)

    SciTech Connect

    Schemme, T. Krampf, A.; Kuepper, K.; Wollschläger, J.; Bertram, F.; Kuschel, T.

    2015-09-21

    Iron oxide films were reactively grown on iron buffer films, which were deposited before on MgO(001) substrates to analyze the influence of the initial iron buffer layers on the magnetic properties of the magnetite films. X-ray photoelectron spectroscopy and low energy electron diffraction showed that magnetite films of high crystalline quality in the surface near region were formed by this two-step deposition procedure. The underlying iron film, however, was completely oxidized as proved by x-ray reflectometry and diffraction. The structural bulk quality of the iron oxide film is poor compared to magnetite films directly grown on MgO(001). Although the iron film was completely oxidized, we found drastically modified magnetic properties for these films using the magnetooptic Kerr effect. The magnetite films had strongly increased coercive fields, and their magnetic in-plane anisotropy is in-plane rotated by 45∘ compared to magnetite films formed directly by one step reactive growth on MgO(001)

  9. Redox cycling of Fe(II) and Fe(III) in magnetite by Fe-metabolizing bacteria

    SciTech Connect

    Byrne, James; Klueglein, Nicole; Pearce, Carolyn I.; Rosso, Kevin M.; Appel, Erwin; Kappler, Andreas

    2015-03-26

    Despite the regular occurrence of both magnetite and iron-metabolizing bacteria in the same environments, it is currently unknown whether the iron(II) and iron(III) in magnetite can be cycled between different bacteria and whether or how magnetic properties are affected by this metabolic activity. We show through magnetic and spectroscopic measurements that the phototrophic Fe(II)-oxidizer Rhodopseudomonas palustris TIE-1 can oxidize solid-phase magnetite nanoparticles using light energy, leading to a decrease in the measured magnetic susceptibility (MS). This process likely occurs at the surface and is reversible in the dark by the Fe(III)-reducer Geobacter sulfurreducens resulting in an increase in MS. These results show that iron ions bound in highly crystalline mineral magnetite are bioavailable as electron stores and electron sinks under varying environmental conditions, making magnetite a potential “biogeobattery” during day/night cycles. These findings are relevant for environmental studies and reinforce the impact of microbial redox processes on the global iron cycle.

  10. Simultaneously discrete biomineralization of magnetite and tellurium nanocrystals in magnetotactic bacteria.

    PubMed

    Tanaka, Masayoshi; Arakaki, Atsushi; Staniland, Sarah S; Matsunaga, Tadashi

    2010-08-01

    Magnetotactic bacteria synthesize intracellular magnetosomes comprising membrane-enveloped magnetite crystals within the cell which can be manipulated by a magnetic field. Here, we report the first example of tellurium uptake and crystallization within a magnetotactic bacterial strain, Magnetospirillum magneticum AMB-1. These bacteria independently crystallize tellurium and magnetite within the cell. This is also highly significant as tellurite (TeO(3)(2-)), an oxyanion of tellurium, is harmful to both prokaryotes and eukaryotes. Additionally, due to its increasing use in high-technology products, tellurium is very precious and commercially desirable. The use of microorganisms to recover such molecules from polluted water has been considered as a promising bioremediation technique. However, cell recovery is a bottleneck in the development of this approach. Recently, using the magnetic property of magnetotactic bacteria and a cell surface modification technology, the magnetic recovery of Cd(2+) adsorbed onto the cell surface was reported. Crystallization within the cell enables approximately 70 times more bioaccumulation of the pollutant per cell than cell surface adsorption, while utilizing successful recovery with a magnetic field. This fascinating dual crystallization of magnetite and tellurium by magnetotactic bacteria presents an ideal system for both bioremediation and magnetic recovery of tellurite.

  11. Novel carboxylated PEG-coating on magnetite nanoparticles designed for biomedical applications

    NASA Astrophysics Data System (ADS)

    Illés, Erzsébet; Tombácz, Etelka; Szekeres, Márta; Tóth, Ildikó Y.; Szabó, Ákos; Iván, Béla

    2015-04-01

    Fabrication of PEG coating on magnetite nanoparticles (MNPs) is one of the most favoured ways to ensure biocompatibility. Surface modification of magnetite by an own-prepared comb-like PEG-copolymer (PEGA-AA) was compared with two commercially available ones (carboxy-PEG (PEG-C) and phosphate-PEG (PEG-P)). ATR FT-IR data revealed that all polymers form complexes on the surface of MNPs. Electrophoresis and dynamic light scattering (DLS) experiments showed that both the type and quantity of the polymers' anchoring groups influence the aggregation of coated nanomagnets. PEG-C shell does not provide excess negative charges, so magnetite particles became aggregated. However PEG-P and PEGA-AA gradually modify the surface: neutralizing the originally positively charged MNPs below loading 0.5 mmol/g, while above it a polyanionic layer forms on nanomagnets dispersing them in salty media at pH ~6.5. The PEGA-AA comb-like copolymer is more efficient for MNPs PEGylation due to the uniform distribution of carboxylates and PEG chains along the carbon skeleton.

  12. Water treatment using activated carbon supporting silver and magnetite.

    PubMed

    Valušová, Eva; Vandžurová, Anna; Pristaš, Peter; Antalík, Marián; Javorský, Peter

    2012-01-01

    Recent efforts in water purification have led to the development of novel materials whose unique properties can offer effective biocidal capabilities with greater ease of use and at lower cost. In this study, we introduce a novel procedure for the preparation of activated carbon (charcoal) composite in which magnetite and silver are incorporated (MCAG); we also describe the use of this material for the disinfection of surface water. The formation process of magnetic MCAG composite was studied using ultraviolet-visible spectroscopy. The results demonstrated the high sorption efficiency of AgNO₃ to magnetic activated carbon. The antimicrobial capabilities of the prepared MCAG were examined and the results clearly demonstrate their inhibitory effect on total river water bacteria and on Pseudomonas koreensis and Bacillus mycoides cultures isolated from river water. The bacterial counts in river water samples were reduced by five orders of magnitude following 30 min of treatment using 1 g l⁻¹ of MCAG at room temperature. The removal of all bacteria from the surface water samples implies that the MCAG material would be a suitable disinfectant for such waters. In combination with its magnetic character, MCAG would be an excellent candidate for the simple ambulatory disinfection of surface water.

  13. Environmental implications and applications of engineered nanoscale magnetite and its hybrid nanocomposites: A review of recent literature

    EPA Science Inventory

    This review focus on environmental implications and applications of engineered magnetite (Fe3O4) nanoparticles (MNPs) as a single phase or a component of a hybrid nanocomposite that take advantages of their superparamagnetism and high surface area. MNPs are synthesized via co-pre...

  14. Did the massive magnetite "lava flows" of El Laco (Chile) form by magmatic or hydrothermal processes? New constraints from magnetite composition by LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Dare, Sarah A. S.; Barnes, Sarah-Jane; Beaudoin, Georges

    2015-06-01

    The El Laco magnetite deposits consist of more than 98 % magnetite but show field textures remarkably similar to mafic lava flows. Therefore, it has long been suggested that they represent a rare example of an effusive Fe oxide liquid. Field and petrographic evidence, however, suggest that the magnetite deposits represent replacement of andesite flows and that the textures are pseudomorphs. We determined the trace element content of magnetite by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) from various settings at El Laco and compared them with magnetite from both igneous and hydrothermal environments. This new technique allows us to place constraints on the conditions under which magnetite in these supposed magnetite "lava flows" formed. The trace element content of magnetite from the massive magnetite samples is different to any known magmatic magnetite, including primary magnetite phenocrysts from the unaltered andesite host rocks at El Laco. Instead, the El Laco magnetite is most similar in composition to hydrothermal magnetite from high-temperature environments (>500 °C), such as iron oxide-copper-gold (IOCG) and porphyry-Cu deposits. The magnetite trace elements from massive magnetite are characterised by (1) depletion in elements considered relatively immobile in hydrothermal fluids (e.g. Ti, Al, Cr, Zr, Hf and Sc); (2) enrichment in elements that are highly incompatible with magmatic magnetite (rare earth elements (REE), Si, Ca, Na and P) and normally present in very low abundance in magmatic magnetite; (3) high Ni/Cr ratios which are typical of magnetite from hydrothermal environments; and (4) oscillatory zoning of Si, Ca, Mg, REE and most high field strength elements, and zoning truncations indicating dissolution, similar to that formed in hydrothermal Fe skarn deposits. In addition, secondary magnetite in altered, brecciated host rock, forming disseminations and veins, has the same composition as magnetite from the massive

  15. Controlled cobalt doping in biogenic magnetite nanoparticles

    PubMed Central

    Byrne, J. M.; Coker, V. S.; Moise, S.; Wincott, P. L.; Vaughan, D. J.; Tuna, F.; Arenholz, E.; van der Laan, G.; Pattrick, R. A. D.; Lloyd, J. R.; Telling, N. D.

    2013-01-01

    Cobalt-doped magnetite (CoxFe3 −xO4) nanoparticles have been produced through the microbial reduction of cobalt–iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mössbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites. PMID:23594814

  16. Refractory Behaviors of Magnetite-Kaolin Bricks

    NASA Astrophysics Data System (ADS)

    Adeosun, S. O.; Akpan, E. I.; Gbenebor, O. P.; Taiwo, O. O.; Eke, I. J.

    2016-11-01

    In this work, the suitability of using kaolin-magnetite-plastic clay to produce refractory bricks has been experimentally explored. Thirty bricks of different compositions were produced and fired at 1200°C. The density, shrinkage moisture content, loss on ignition, porosity and permeability of the bricks were examined. Results show that the bricks remained stable during firing and thus possess good insulating characteristics. The highest (2.23 g/cm3) and lowest (2.00 g/cm3) bulk densities obtained in this study are higher than the highest bulk density reported for Al dross-filled refractories (1.23 g/cm3). The bricks also possessed very low effective moisture content (10-23%) and very high compression modulus (16-100 MPa) desirable in insulating refractory bricks with high resistance to abrasion.

  17. LA-ICP-MS of magnetite: Methods and reference materials

    USGS Publications Warehouse

    Nadoll, P.; Koenig, A.E.

    2011-01-01

    Magnetite (Fe3O4) is a common accessory mineral in many geologic settings. Its variable geochemistry makes it a powerful petrogenetic indicator. Electron microprobe (EMPA) analyses are commonly used to examine major and minor element contents in magnetite. Laser ablation ICP-MS (LA-ICP-MS) is applicable to trace element analyses of magnetite but has not been widely employed to examine compositional variations. We tested the applicability of the NIST SRM 610, the USGS GSE-1G, and the NIST SRM 2782 reference materials (RMs) as external standards and developed a reliable method for LA-ICP-MS analysis of magnetite. LA-ICP-MS analyses were carried out on well characterized magnetite samples with a 193 nm, Excimer, ArF LA system. Although matrix-matched RMs are sometimes important for calibration and normalization of LA-ICP-MS data, we demonstrate that glass RMs can produce accurate results for LA-ICP-MS analyses of magnetite. Cross-comparison between the NIST SRM 610 and USGS GSE-1G indicates good agreement for magnetite minor and trace element data calibrated with either of these RMs. Many elements show a sufficiently good match between the LA-ICP-MS and the EMPA data; for example, Ti and V show a close to linear relationship with correlation coefficients, R2 of 0.79 and 0.85 respectively. ?? 2011 The Royal Society of Chemistry.

  18. Bats use magnetite to detect the earth's magnetic field.

    PubMed

    Holland, Richard A; Kirschvink, Joseph L; Doak, Thomas G; Wikelski, Martin

    2008-02-27

    While the role of magnetic cues for compass orientation has been confirmed in numerous animals, the mechanism of detection is still debated. Two hypotheses have been proposed, one based on a light dependent mechanism, apparently used by birds and another based on a "compass organelle" containing the iron oxide particles magnetite (Fe(3)O(4)). Bats have recently been shown to use magnetic cues for compass orientation but the method by which they detect the Earth's magnetic field remains unknown. Here we use the classic "Kalmijn-Blakemore" pulse re-magnetization experiment, whereby the polarity of cellular magnetite is reversed. The results demonstrate that the big brown bat Eptesicus fuscus uses single domain magnetite to detect the Earths magnetic field and the response indicates a polarity based receptor. Polarity detection is a prerequisite for the use of magnetite as a compass and suggests that big brown bats use magnetite to detect the magnetic field as a compass. Our results indicate the possibility that sensory cells in bats contain freely rotating magnetite particles, which appears not to be the case in birds. It is crucial that the ultrastructure of the magnetite containing magnetoreceptors is described for our understanding of magnetoreception in animals.

  19. A comparison between acoustic properties and heat effects in biogenic (magnetosomes) and abiotic magnetite nanoparticle suspensions

    NASA Astrophysics Data System (ADS)

    Józefczak, A.; Leszczyński, B.; Skumiel, A.; Hornowski, T.

    2016-06-01

    Magnetic nanoparticles show unique properties and find many applications because of the possibility to control their properties using magnetic field. Magnetic nanoparticles are usually synthesized chemically and modification of the particle surface is necessary. Another source of magnetic nanoparticles are various magnetotactic bacteria. These biogenic nanoparticles (magnetosomes) represent an attractive alternative to chemically synthesized iron oxide particles because of their unique characteristics and a high potential for biotechnological and biomedical applications. This work presents a comparison between acoustic properties of biogenic and abiotic magnetite nanoparticle suspensions. Experimental studies have shown the influence of a biological membrane on the ultrasound properties of magnetosomes suspension. Finally the heat effect in synthetic and biogenic magnetite nanoparticles is also discussed. The experimental study shows that magnetosomes present good heating efficiency.

  20. Chains of magnetite crystals in the meteorite ALH84001: evidence of biological origin.

    PubMed

    Friedmann, E I; Wierzchos, J; Ascaso, C; Winklhofer, M

    2001-02-27

    The presence of magnetite crystal chains, considered missing evidence for the biological origin of magnetite in ALH84001 [Thomas-Keprta, K. L., Bazylinski, D. A., Kirschvink, J. L., Clemett, S. J., McKay, D. S., Wentworth, S. J., Vali, H., Gibson, E. K., Jr., & Romanek, C. S. (2000) Geochim. Cosmochim. Acta 64, 4049-4081], is demonstrated by high-power stereo backscattered scanning electron microscopy. Five characteristics of such chains (uniform crystal size and shape within chains, gaps between crystals, orientation of elongated crystals along the chain axis, flexibility of chains, and a halo that is a possible remnant of a membrane around chains), observed or inferred to be present in magnetotactic bacteria but incompatible with a nonbiological origin, are shown to be present. Although it is unlikely that magnetotactic bacteria were ever alive in ALH84001, decomposed remains of such organisms could have been deposited in cracks in the rock while it was still on the surface on Mars.

  1. 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.

  2. Synthesis and characterization of Gd-doped magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhang, Honghu; Malik, Vikash; Mallapragada, Surya; Akinc, Mufit

    2017-02-01

    Synthesis of magnetite nanoparticles has attracted increasing interest due to their importance in biomedical and technological applications. Tunable magnetic properties of magnetite nanoparticles to meet specific requirements will greatly expand the spectrum of applications. Tremendous efforts have been devoted to studying and controlling the size, shape and magnetic properties of magnetite nanoparticles. Here we investigate gadolinium (Gd) doping to influence the growth process as well as magnetic properties of magnetite nanocrystals via a simple co-precipitation method under mild conditions in aqueous media. Gd doping was found to affect the growth process leading to synthesis of controllable particle sizes under the conditions tested (0-10 at% Gd3+). Typically, undoped and 5 at% Gd-doped magnetite nanoparticles were found to have crystal sizes of about 18 and 44 nm, respectively, supported by X-ray diffraction and transmission electron microscopy. Our results showed that Gd-doped nanoparticles retained the magnetite crystal structure, with Gd3+ randomly incorporated in the crystal lattice, probably in the octahedral sites. The composition of 5 at% Gd-doped magnetite was Fe(3-x)GdxO4 (x=0.085±0.002), as determined by inductively coupled plasma mass spectrometry. 5 at% Gd-doped nanoparticles exhibited ferrimagnetic properties with small coercivity ( 65 Oe) and slightly decreased magnetization at 260 K in contrast to the undoped, superparamagnetic magnetite nanoparticles. Templation by the bacterial biomineralization protein Mms6 did not appear to affect the growth of the Gd-doped magnetite particles synthesized by this method.

  3. Synthesis of thoria nano-particles at low temperature through base electrogeneration on steel 316L surface: Effect of current density

    NASA Astrophysics Data System (ADS)

    Yousefi, Taher; Torab-Mostaedi, Meisam; Mobtaker, Hossein Ghasemi; Keshtkar, Ali Reza

    2016-10-01

    The strategy developed in this study, offers significant advantages (simplicity and cleanness of method and also a product purity and new morphology of the product) over the conventional routes for the synthesis of ThO2 nanostructure. The effect of current density on morphology was studied. The synthesized powder was characterized by means of Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM, Phillips EM 2085) Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared (FT-IR) spectroscopy. The results show that the current density has a great effect on the morphology of the samples. The average size of the particles decreases as the applied current density increases and the average size of the samples decreases from 50 to 15 nm when the current density increases from 2 to 5 mA cm-2.

  4. Optimization of band gap in Ni-substituted magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Rana, Geeta; Johri, Umesh C.

    2013-06-01

    The excellent biocompatibility and magnetic properties of magnetite nanoparticles have encouraged a tremendous amount of research in the last decade. Lots of work has been reported on their magnetic and electric properties but little work is done to study the optical properties (band gap). In the present work Ni is substituted with varying concentration in magnetite nanoparticles. XRD patterns confirm their spinel phase and particle size is estimated using TEM. The UV-visible reflectance and Kubelka-Munk function plot gives the optical band gap of NixFe1-xFe2O4 which is found to be decreasing with respect to the pure magnetite samples.

  5. Search for magnetite in lunar rocks and fines.

    PubMed

    Jedwab, J; Herbosch, A; Wollast, R; Naessens, G; Van Geen-Peers, N

    1970-01-30

    Magnetite crystals larger than 2 micrometers are absent from rocks and fines. Smaller opaque spheres in the fines can tentatively be identified as magnetite. Their concentration is not higher than 1 x 10(-6) particle per particle smaller than 1 millimeter. In the fines from the sampling site, the contribution of material similar to type 1 carbonaceous meteorites is insignificant, either because it never existed, or because it was evaporated or comminuted by impact or was diluted by indigenous material. Other magnetite habits typical of carbonaceous meteorites or possibly of cosmic dust or comets were also sought without success-such as rods, platelets, framboids, spherulites, and idiomorphic crystals.

  6. Synthesis and Characterization of Magnetite/Zinc Oxide and Magnetite/Zinc Manganese Sulfide Core-Shell Heterostructured Nanoparticles

    NASA Astrophysics Data System (ADS)

    Beltran Huarac, Juan Carlos

    Currently, core-shell heterostructured nanosystems are emerging as next-generation materials due to their potential multifunctionalities in contrast with the more limited single-component counterparts. Systematic investigation of core-shell nanostructures of ZnO and bare-and-doped-Mn2+ ZnS nanocrystals on the surface of magnetite nanoparticles (Fe3O 4) was performed. The magnetite cores were prepared via the co-precipitation method and were next treated with an appropriate surfactant. The Fe3 O4/(S) (S=ZnO and ZnMnS) core-shell nanoparticles were obtained by an aqueous solution method at room temperature. The structural tests were carried out using an x-ray diffractometer (XRD) which showed the development of crystalline phases of cubic Fe3O4, hexagonal ZnO wurtzite and cubic ZnS. These patterns also established the matching between bare and doped-Mn2+ ZnS diffraction peaks. Broadness of the diffraction peaks evidenced the formation of nanosize phases. The transmission electron microscopy (TEM) confirmed the deposition of a semiconductor shell on the surface of superparamagnetic Fe3O4 nanoparticles. The UV-Vis spectra showed the presence of a strong absorption peak and photoluminescence (PL) spectra displayed the emission peak due to excitonic recombination and a very weak defect-related emission peak suggesting the rearrangement of electronic configuration in the core-shell structures when ZnO is surrounding the core. These spectra also displayed the strong emission peak attributed to paramagnetic ion Mn2+ when acted as dopant in the host ZnS structure. The study of the magnetic properties was carried out using a vibrating sample magnetometer (VSM) which evidenced considerable drop in the saturation magnetization of the Fe3O4/ZnO nanoparticles in comparison to individual Fe3O4 ones. For the Fe3O4/ZnMnS system a slight ferromagnetic behavior at room temperature was observed. The chemical composition of these nanomaterials was performed by x-ray photoelectron

  7. Magnetite as Possible Template for the Synthesis of Chiral Organics in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.

    2014-01-01

    The main goal of the Japanese Aerospace Ex-ploration Agency (JAXA) Hayabusa-2 mission is to visit and return to Earth samples of a C-type asteroid (162173) 1999 JU3 in order to understand the origin and nature of organic materials in the Solar System. Life on Earth shows preference towards the set of organics with particular spatial arrangements, this 'selectivity' is a crucial criterion for life. With only rare exceptions, life 'determines' to use the left- (L-) form over the right- (D-) form of amino acids, resulting in a L-enantiomeric excess (ee). Recent studies have shown that L-ee is found within the alpha-methyl amino acids in meteorites [1, 2], which are amino acids with rare terrestrial occurrence, and thus point towards a plausible abiotic origin for ee. One of the proposed origins of chiral asymmetry of amino acids in meteorites is their formation with the presence of asymmetric catalysts [3]. The catalytic mineral grains acted as a surface at which nebular gases (CO, H2 and NH3) were allowed to condense and react through Fisher Tropsch type (FTT) syntheses to form the organics observed in meteorites [4]. Magnetite is shown to be an effective catalyst of the synthesis of amino acids that are commonly found in meteorites [5]. It has also taken the form as spiral magnetites (a.k.a. 'plaquettes'), which were found in various carbonaceous chondrites (CCs), including C2s Tagish Lake and Esseibi, CI Orgueil, and CR chondrites [e.g., 6, 7, 8]. In addition, L-ee for amino acids are common in the aqueously altered CCs, as opposed to the unaltered CCs [1]. It seems possible that the synthesis of amino acids with chiral preferences is correlated to the alteration process experienced by the asteroid parent body, and related to the configuration of spiral magnetite catalysts. Since C-type asteroids are considered to be enriched in organic matter, and the spectral data of 1999 JU3 indicates a certain de-gree of aqueous alteration [9], the Hayabusa-2 mission serves as

  8. Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Knipping, Jaayke L.; Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Barra, Fernando; Deditius, Artur P.; Wälle, Markus; Heinrich, Christoph A.; Holtz, François; Munizaga, Rodrigo

    2015-12-01

    Iron oxide-apatite (IOA) deposits are an important source of iron and other elements (e.g., REE, P, U, Ag and Co) vital to modern society. However, their formation, including the namesake Kiruna-type IOA deposit (Sweden), remains controversial. Working hypotheses include a purely magmatic origin involving separation of an Fe-, P-rich, volatile-rich oxide melt from a Si-rich silicate melt, and precipitation of magnetite from an aqueous ore fluid, which is either of magmatic-hydrothermal or non-magmatic surface or metamorphic origin. In this study, we focus on the geochemistry of magnetite from the Cretaceous Kiruna-type Los Colorados IOA deposit (∼350 Mt Fe) located in the northern Chilean Iron Belt. Los Colorados has experienced minimal hydrothermal alteration that commonly obscures primary features in IOA deposits. Laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) transects and electron probe micro-analyzer (EPMA) wavelength-dispersive X-ray (WDX) spectrometry mapping demonstrate distinct chemical zoning in magnetite grains, wherein cores are enriched in Ti, Al, Mn and Mg. The concentrations of these trace elements in magnetite cores are consistent with igneous magnetite crystallized from a silicate melt, whereas magnetite rims show a pronounced depletion in these elements, consistent with magnetite grown from an Fe-rich magmatic-hydrothermal aqueous fluid. Further, magnetite grains contain polycrystalline inclusions that re-homogenize at magmatic temperatures (>850 °C). Smaller inclusions (<5 μm) contain halite crystals indicating a saline environment during magnetite growth. The combination of these observations are consistent with a formation model for IOA deposits in northern Chile that involves crystallization of magnetite microlites from a silicate melt, nucleation of aqueous fluid bubbles on magnetite surfaces, and formation and ascent of buoyant fluid bubble-magnetite aggregates. Decompression of the fluid-magnetite aggregate

  9. Magnetite Plaquettes Provide an Extraterrestrial Source of Asymmetric Components

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.; Martinez, J. E.

    2015-01-01

    Molecular selectivity is a crucial criterion for life. A possible abiotic mechanism that can produce chiral asymmetry in meteoritic amino acids is their formation with the presence of asymmetric catalysts. Magnetite (Fe3O4), a common mineral in some carbonaceous chondrites (CCs), has been shown to be an effective catalyst for the formation of amino acids that are commonly found in these meteorites. Magnetite sometimes takes the form of plaquettes that consist of barrel-shaped stacks of magnetite disks that resemble a spiral. However, a widely accepted description of the internal morphology of this particular magnetite form is still lacking, which is necessary in order to confirm or disprove the spiral configuration.

  10. Starch-modified magnetite nanoparticles for impregnation into cartilage

    NASA Astrophysics Data System (ADS)

    Soshnikova, Yulia M.; Roman, Svetlana G.; Chebotareva, Natalia A.; Baum, Olga I.; Obrezkova, Mariya V.; Gillis, Richard B.; Harding, Stephen E.; Sobol, Emil N.; Lunin, Valeriy V.

    2013-11-01

    The paper presents preparation and characterization of starch-modified Fe3O4 nanoparticles (NPs) in aqueous dispersion after impregnation into healthy and damaged types of cartilage. We show that starch-modified dispersion has a narrower size distribution than a non-stabilized one. The average hydrodynamic radius of magnetite NPs in a dispersion used for impregnation into cartilage is (48 ± 1) nm with the width of the distribution from 5 to 200 nm. We investigate stability of aqueous magnetite NPs dispersions during storage and with increase in temperature (up to 70 °C). We find that polydisperse magnetite NPs can penetrate into cartilage and the size and concentration of impregnated particles depend on the organization of the tissue structure. The results confirm the possibility of application of magnetite NPs in diagnostics and laser treatment of degenerative cartilage deceases.

  11. Synthesis of magnetite nanoparticles in the presence of aminoacids

    NASA Astrophysics Data System (ADS)

    Marinescu, Gabriela; Patron, Luminita; Culita, Daniela C.; Neagoe, Cristian; Lepadatu, Costinel I.; Balint, Ioan; Bessais, Lotfi; Cizmas, Corneliu Bazil

    2006-12-01

    A new synthesis route to prepare magnetite nanoparticles in only one step is described. The precipitation of magnetite is performed in the presence of aminoacid solution. The experimental protocol is original and the nanomagnetites are characterized by XRD, FTIR, TEM and SQUID magnetometry. A theoretical study of the consistent experimental results was performed using QSPR (Quantitative Structure Property Relationsheep). According with these studies the synthesized nanoparticles seem to be organized into a core-shell system, where the inner-core is formed from unit cells of magnetite. A way to control the self-assembly and the physical properties of the synthesized nanoparticles consists in their correlation with descriptors representing the aminoacid chemical structures. Using quantum chemical as well as the other simplest original descriptors it was found a relationship between the used aminoacids and the magnetization, nanoparticles diameter, magnetite core diameter and the (Fe3O4)8 cells in each nanoparticle core.

  12. Electrophoretic mobility of magnetite particles in high temperature water

    SciTech Connect

    Vidojkovic, Sonja; Rodriguez-Santiago, V; Fedkin, Mark V.; Wesolowski, David J; Lvov, Serguei N.

    2011-01-01

    Magnetite(Fe3O4) isoneofthemostcommonoxidesformingdepositsandparticulatephasesin industrialhightemperaturewatercircuits.Itscolloidalcharacteristicsplayaprincipalroleinthe mechanismofdepositformationandcanbeusedascontrollingfactorstopreventorminimizedeposit formationanddamageofindustrialpipelinesduetounder-depositcorrosion.Inthisstudy,ahigh temperatureparticleelectrophoresistechniquewasemployedtomeasurethezetapotentialatthe magnetite/waterinterface the parameterthatcontrolscolloidalstabilityofparticles,theiraggrega- tion, anddeposition.Themeasurementsweremadeattemperaturesupto200 1C overawiderangeofpH. The isoelectricpointsofmagnetite,atwhichthedepositionofparticlesisincreased,weredeterminedatpH 6.35, 6.00,5.25,and5.05fortemperatures25,100,150,and200 1C, respectively.Theobserved temperaturedependenceofzetapotentialandtheisoelectricpHpointofmagnetitecanhelptoexplain the extentofinteractionsbetweenthecolloidalparticlesandthesteelwallsurfacesunderhydro- thermalconditions,andindicatemethodsforcontrollingandmitigatingoxidedepositioninhigh temperaturewatercycles.

  13. Amino-functionalized silica magnetite nanoparticles for the simultaneous removal of pollutants from aqueous solution

    NASA Astrophysics Data System (ADS)

    Hozhabr Araghi, Samira; Entezari, Mohammad H.

    2015-04-01

    Amino-functionalized silica magnetite nanoparticles (A-S-MNPs) have been prepared through coating of sono-synthesized magnetite nanoparticles (MNPs) in a basic medium by SiO2. Then, the resultant silica magnetite nanoparticles (S-MNPs) were modified with 3-aminpropyltriethoxysilane (APTES). The modification was carried out by the organic solvent method in dry hexane to graft amine groups on the surface. The adsorption behavior of this novel magnetic sorbent was studied for the simultaneous removal of two organic pollutants containing the sulfonate group, e.g., Reactive Black 5 (RB5) and sodium dodecylbenzenesulfonate (SDBS) in aqueous solutions. The results show that a pseudo-second-order model fits well the experimental data and the rate constant of adsorption for SDBS is higher than for RB5. The adsorption capacity was obtained by the Langmuir isotherm. The qmax was 83.33 and 62.5 mg/g for RB5 and SDBS at pH 2 and 298 K, respectively. Furthermore, the loaded A-S-MNPs can be recovered easily from aqueous solution by magnetic separation and regenerated by simply washing with 0.1 M NaOH solution. Therefore, the synthesized novel magnetic sorbent can be used as an effective and recyclable adsorbent for the simultaneous removal of dye and surfactant from aqueous solutions.

  14. Enhanced stability of polyacrylate-coated magnetite nanoparticles in biorelevant media.

    PubMed

    Hajdú, Angéla; Szekeres, Márta; Tóth, Ildikó Y; Bauer, Rita A; Mihály, Judith; Zupkó, István; Tombácz, Etelka

    2012-06-01

    Magnetite nanoparticles (MNPs) were prepared by alkaline hydrolysis of Fe(II) and Fe(III) chlorides. Adsorption of polyacrylic acid (PAA) on MNPs was measured at pH=6.5±0.3 and I=0.01 M (NaCl) to find the optimal PAA amount for MNP stabilization under physiological conditions. We detected an H-bond formation between magnetite surface groups and PAA by ATR-FTIR measurements, but bonds of metal ion-carboxylate complexes, generally cited in literature, were not identified at the given pH and ionic strength. The dependence of the electrokinetic potential and the aggregation state on the amount of added PAA at various pHs was measured by electrophoretic mobility and dynamic light-scattering methods. The electrokinetic potential of the naked MNPs was low at near physiological pH, but PAA adsorption overcharged the particles. Highly negatively charged, well-stabilized carboxylated MNPs formed via adsorption of PAA in an amount of approximately ten times of that necessary to compensate the original positive charge of the magnetite. Coagulation kinetics experiments revealed gradual enhancement of salt tolerance at physiological pH from ~0.001 M at no added PAA up to ~0.5 M at 1.12 mmol/g PAA. The PAA-coated MNPs exert no substantial effect on the proliferation of malignant (HeLa) or non-cancerous fibroblast cells (MRC-5) as determined by means of MTT assays.

  15. Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging.

    PubMed

    Kale, Anup; Kale, Sonia; Yadav, Prasad; Gholap, Haribhau; Pasricha, Renu; Jog, J P; Lefez, Benoit; Hannoyer, Béatrice; Shastry, Padma; Ogale, Satishchandra

    2011-06-03

    A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

  16. Magnetite/CdTe magnetic-fluorescent composite nanosystem for magnetic separation and bio-imaging

    NASA Astrophysics Data System (ADS)

    Kale, Anup; Kale, Sonia; Yadav, Prasad; Gholap, Haribhau; Pasricha, Renu; Jog, J. P.; Lefez, Benoit; Hannoyer, Béatrice; Shastry, Padma; Ogale, Satishchandra

    2011-06-01

    A new synthesis protocol is described to obtain a CdTe decorated magnetite bifunctional nanosystem via dodecylamine (DDA) as cross linker. High resolution transmission electron microscopy (HRTEM), energy-dispersive x-ray spectroscopy (EDAX), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and fluorescence microscopy are used to characterize the constitution, size, composition and physical properties of these superparamagnetic-fluorescent nanoparticles. These CdTe decorated magnetite nanoparticles were then functionalized with anti-epidermal growth factor receptor (EGFR) antibody to specifically target cells expressing this receptor. The EGFR is a transmembrane glycoprotein and is expressed on tumor cells from different tissue origins including human leukemic cell line Molt-4 cells. The magnetite-CdTe composite nanosystem is shown to perform excellently for specific selection, magnetic separation and fluorescent detection of EGFR positive Molt-4 cells from a mixed population. Flow cytometry and confocal laser scanning microscopy results show that this composite nanosystem has great potential in antibody functionalized magnetic separation and imaging of cells using cell surface receptor antibody.

  17. Controls on Soluble Pu Concentrations in PuO2/Magnetite Suspensions

    SciTech Connect

    Felmy, Andrew R.; Moore, Dean A.; Pearce, Carolyn I.; Conradson, Steven D.; Qafoku, Odeta; Buck, Edgar C.; Rosso, Kevin M.; Ilton, Eugene S.

    2012-11-06

    Time-dependent reduction of PuO2(am) was studied over a range of pH values in the presence of aqueous Fe(II) and magnetite (Fe3O4) nanoparticles. At early time frames (up to 56 days) very little aqueous Pu was mobilized from PuO2(am), even though measured pH and redox potentials, coupled to equilibrium thermodynamic modeling indicated the potential for significant reduction of PuO2(am) to relatively soluble Pu(III). Introduction of Eu(III) or Nd(III) to the suspensions as competitive cations to displace possible sorbed Pu(III) resulted in the release of significant concentrations of aqueous Pu. However, the similarity of aqueous Pu concentrations that resulted from the introduction of Eu(III)/Nd(III) to suspensions with and without magnetite indicated that the Pu was displaced from the PuO2(am), not from magnetite. The fact that soluble forms of Pu can be displaced from the surface of PuO2(am) represents a potential, but previously unidentified, source of Pu to aqueous solution or subsurface groundwaters.

  18. The Origin of Magnetite Crystals in ALH84001 Carbonate Disks

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; Clemett, S. J.; Wentworth, S. J.; McKay, D. S.; Gibson, E. K., Jr.

    2012-01-01

    Martian meteorite ALH84001 preserves evidence of interaction with aqueous fluids while on Mars in the form of microscopic carbonate disks believed to have formed approx 3.9 Ga ago at beginning of the Noachian epoch. Intimately associated within and throughout these carbonate disks are nanocrystal magnetites (Fe3O4) with unusual chemical and physical properties, whose origins have become the source of considerable debate. One group of hypotheses argues that these magnetites are the product of partial thermal decomposition of the host carbonate. Alternatively, the origins of magnetite and carbonate may be unrelated; that is, from the perspective of the carbonate the magnetite is allochthonous. We have sought to resolve between these hypotheses through the detailed characterized of the compositional and structural relationships between the carbonate disks, their associated magnetites and the orthopyroxene matrix in which they are embedded. Comparison of these results with experimental thermal decomposition studies of sideritic carbonates conducted under a range of heating scenarios suggests that the magnetite nanocrystals in the ALH84001 carbonate disks are not the products of thermal decomposition.

  19. EPR evidence for maghemitization of magnetite in a tropical soil

    NASA Astrophysics Data System (ADS)

    Fischer, H.; Luster, J.; Gehring, A. U.

    2007-06-01

    Electron paramagnetic spectroscopy (EPR) was used in combination with standard rock magnetic methods to study magnetic minerals in a tropical soil. The susceptibility and hysteresis measurements showed magnetite grains with a Curie temperature near 850 K as the dominant magnetic remanence carriers in the soil. A minor Ti content in the magnetite was found by energy dispersive X-ray analysis. In order to get insight into the weathering status of the magnetite, different chemical treatments, including oxalate and citrate-bicarbonate-dithionite (CBD) extraction, were applied to the soil samples. The hysteretic properties exhibited no significant differences between the untreated and the CBD or oxalate treated samples. By contrast, the comparison of the EPR spectra revealed a significant broadening of the linewidth (δB) and a shift of the g-values (geff) to lower fields after the CBD treatment. Furthermore, the spectral parameters geff and δB exhibited an angular dependence. At low temperature, the CBD treated samples showed a jump in δB between 120 and 100 K, the temperature range characteristic for the Verwey transition in magnetite. The changes in the spectral properties after the CBD treatment, which dissolves ferric oxides, were attributed to the removal of maghemite formed by the oxidation of magnetite, that is, during the maghemitization of the magnetite grains.

  20. Magnetite Nucleation in Mantle Xenoliths During Quasi-Adiabatic Ascent

    NASA Astrophysics Data System (ADS)

    Walsh, K. B., Jr.; Filiberto, J.; Friedman, S. A.; Knafelc, J.; Conder, J. A.; Ferre, E. C.; Khakhalova, E.; Feinberg, J. M.; Neal, C. R.; Ionov, D. A.; Hernandez, F. M.

    2014-12-01

    Can magnetite be a stable phase in the lithospheric mantle? Equilibrium-based thermodynamic calculations and petrologic models predict that it should not be stable. Studies of mantle xenoliths during the 1980s concluded that even though there were rare exceptions, mantle rocks do not host sufficient concentrations of ferromagnetic minerals and are too hot to allow any magnetic remanence. Thus, conventional wisdom dictates that the Moho constitutes a fundamental magnetic boundary. Yet, growing evidence from a more complete global mantle xenolith survey indicates the presence of ferromagnetic minerals in mantle materials. Examination of mantle xenoliths devoid of serpentinization and meteoric alteration show the presence of ferromagnetic minerals within primary silicate mineral phases, including olivine, pyroxene, and spinel. Nucleation of these magnetic minerals could occur at three different stages: in-situ in the mantle, upon ascent, and at the surface. This study reports the results of laboratory-based quasi-adiabatic decompression experiments that aim to simulate the ascent of mantle xenoliths through the lithosphere and test if magnetite growth is promoted during the process. The starting material for these experiments is San Carlos olivine, which holds a magnetic remanence of less than ~10-10 A/m2-1kg2 (the detection limit of the vibrating sample magnetometer). This low starting remanence will allow us to identify whether new magnetic minerals are formed during the decompression experiments using either vibrating sample magnetometry or SQUID-based rock magnetometers. All olivine grains in these experiments were hand-picked under a light microscope in an effort to avoid the inclusion of grains with spurious magnetic minerals. Olivine powders from these carefully selected grains will be used to represent average mantle olivine compositions (Fo90-Fo92). Experiments will start at 1 GPa and be decompressed to 0.3 GPa over 60 hrs at constant temperature (1200° C

  1. Effect of dissolved organic matter on the stability of magnetite nanoparticles under different pH and ionic strength conditions.

    PubMed

    Hu, Jun-Dong; Zevi, Yuniati; Kou, Xiao-Ming; Xiao, John; Wang, Xue-Jun; Jin, Yan

    2010-07-15

    Upon release of engineered nanoparticles (NPs) into the subsurface environment, their fate and transport and hence their potential environmental and public health impacts will largely depend on how stable these NPs are as suspended particles in the natural environment. In this study, we systematically examine the effect of humic acid (HA) on surface charge status and aggregation potential of magnetite (Fe(3)O(4)) NPs, selected as a model for metal oxide NPs, over a wide range of solution pH and ionic strength. Through zeta potential (ZP) measurements, we found that HA can adsorb to magnetite particles hence modifying their surface charge status. At low loadings, the presence of HA can induce a shift in the point zero of charge of due to partial neutralization of the positive charges on magnetite NPs. At high loadings, however, HA is capable of completely cover magnetite particles giving rise to a suspension ZP profile similar to its own (observed in presence of 20 mg L(-)(1) HA). These impacts on surface charge correspond well with the observed aggregation behaviors in the absence and presence of HA. From the dynamic light scattering (DLS) measurements, fast aggregation, which is independent of solution chemistry, took place when the pH is close to the point zero charge (PZC) and the ionic strength is above the critical coagulation concentration (CCC). At high ionic strength, a small dose (2 mg L(-)(1)) of HA stabilized the NPs' suspension significantly. This stabilization effect is substantially enhanced with increasing HA concentration. The calculated DLVO (Derjaguin-Landau-Verwey-Overbeek) interaction energy profiles, using experimentally determined values of Hamaker constant, adequately support the experimental observations. The DLVO analysis further reveals the possible presence of secondary energy minima and the possibility of deaggregation of magnetite agglomerates. The complexation of HA-NPs and the HA effects on NPs aggregations were confirmed by atomic

  2. Magnetite impregnation effects on the sorbent properties of activated carbons and biochars.

    PubMed

    Han, Zhantao; Sani, Badruddeen; Mrozik, Wojciech; Obst, Martin; Beckingham, Barbara; Karapanagioti, Hrissi K; Werner, David

    2015-03-01

    This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m(2)/g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m(2)/g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons.

  3. Atomic layer deposition of superparamagnetic and ferrimagnetic magnetite thin films

    SciTech Connect

    Zhang, Yijun; Liu, Ming E-mail: wren@mail.xjtu.edu.cn Ren, Wei E-mail: wren@mail.xjtu.edu.cn; Zhang, Yuepeng; Chen, Xing; Ye, Zuo-Guang E-mail: wren@mail.xjtu.edu.cn

    2015-05-07

    One of the key challenges in realizing superparamagnetism in magnetic thin films lies in finding a low-energy growth way to create sufficiently small grains and magnetic domains which allow the magnetization to randomly and rapidly reverse. In this work, well-defined superparamagnetic and ferrimagnetic Fe{sub 3}O{sub 4} thin films are successfully prepared using atomic layer deposition technique by finely controlling the growth condition and post-annealing process. As-grown Fe{sub 3}O{sub 4} thin films exhibit a conformal surface and poly-crystalline nature with an average grain size of 7 nm, resulting in a superparamagnetic behavior with a blocking temperature of 210 K. After post-annealing in H{sub 2}/Ar at 400 °C, the as-grown α−Fe{sub 2}O{sub 3} sample is reduced to Fe{sub 3}O{sub 4} phase, exhibiting a ferrimagnetic ordering and distinct magnetic shape anisotropy. Atomic layer deposition of magnetite thin films with well-controlled morphology and magnetic properties provides great opportunities for integrating with other order parameters to realize magnetic nano-devices with potential applications in spintronics, electronics, and bio-applications.

  4. Comparative evaluation of the three different surface treatments - conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study.

    PubMed

    Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S

    2015-04-01

    The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial.

  5. Comparative evaluation of the three different surface treatments – conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study

    PubMed Central

    Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S.

    2015-01-01

    The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial. PMID:26015762

  6. XAS signatures of Am(III) adsorbed onto magnetite and maghemite

    NASA Astrophysics Data System (ADS)

    Finck, N.; Radulescu, L.; Schild, D.; Rothmeier, M.; Huber, F.; Lützenkirchen, J.; Rabung, T.; Heberling, F.; Schlegel, M. L.; Dideriksen, K.; Nedel, S.; Geckeis, H.

    2016-05-01

    Trivalent americium was adsorbed on magnetite and maghemite under similar chemical conditions and the local environment probed by EXAFS spectroscopy. In both samples, partially hydrated Am(III) binds the surface but slightly different surface complexes were identified. On Fe3O4, Am(III) forms monomeric tridentate surface complexes similar to that reported for Pu(III) at the (111) surface. In contrast, the lower number of detected Fe atoms may suggest that Am(III) forms monomeric bidentate surface complexes on γ-Fe2O3. Alternatively, the lower Fe coordination number can also be due to the presence of vacancies in maghemite. XPS data imply very similar binding environments for Am at both Fe oxide surfaces.

  7. Electrochemical and spectroscopic evidence on the one-electron reduction of U(VI) to U(V) on magnetite

    SciTech Connect

    Yuan, Ke; Ilton, Eugene S.; Antonio, Mark R.; Li, Zhongrui; Cook, Peter J.; Becker, Udo

    2015-05-19

    Reduction of U(VI) to U(IV) on mineral surfaces has been considered as a one-step two electron process. However, stabilized U(V), with no evidence of U(IV), found in recent studies indicates U(VI) can undergo a one electron reduction to U(V) without further progression to U(IV). We investigated the mechanisms of uranium reduction by reducing U(VI) electrochemically on a magnetite electrode at pH 3.4 . The one electron reduction of U(VI) was first confirmed using the cyclic voltammetry method. Formation of nano-size uranium precipitates on the surface of magnetite at reducing potentials and dissolution of the solids at oxidizing potentials were observed by in situ electrochemical AFM. XPS analysis of the magnetite electrodes polarized in uranium solutions at voltages from 0.1 ~ 0.9 V (vs. Ag/AgCl) showed the presence of only U(V) and U(VI). The highest amount of U(V) relative to U(VI) was prepared at 0.7 V, where the longest average U–Oaxial distance of 2.05 ± 0.01 Å was evident in the same sample revealed by EXAFS analysis. The results demonstrate that the electrochemical reduction of U(VI) on magnetite only yields U(V), even at a potential of 0.9 V, which favors the one-electron reduction mechanism. U(V) did not disproportionate but stabilized on magnetite through precipitation of mixed-valence state U(VI)/U(V) solids.

  8. One-step continuous synthesis of functionalized magnetite nanoflowers

    NASA Astrophysics Data System (ADS)

    Thomas, G.; Demoisson, F.; Chassagnon, R.; Popova, E.; Millot, N.

    2016-04-01

    For the first time, functionalized magnetite nanoparticles (Fe3O4 NPs) that form aggregates with a nanoflower morphology were synthesized using a rapid (11 s) one-step continuous hydrothermal process, which was recently modified, and their application as a T 2 magnetic resonance imaging (MRI) contrast agent was evaluated. The nanoparticles functionalized with 3,4-dihydroxy-L-phenylalanine (LDOPA) or 3,4-dihydroxyhydrocinnamic acid (DHCA) consisted of small crystallites of approximately 15 nm of diameter that assembled to form flower-shaped aggregate structures. The Fe3O4-LDOPA nanoflowers exhibited a high transverse relaxivity, r 2 of 418 ± 10 l mmolFe -1 s-1 at 3 T owing to magnetic dipolar interactions, which is twice as that of the commercial Feridex®/Endorem®. The prepared nanostructures were compared with bare Fe3O4 NPs and citrated Fe3O4 NPs. DHCA, LDOPA, and citric acid (CA) were found to have an anti-oxidizing effect and to influence the crystallite size and the lattice parameter of the NPs. DHCA and LDOPA increased the crystallite size, whereas CA decreased it. Surface modification increased the colloidal stability of NPs as compared to bare NPs. Nanoflower suspensions of Fe3O4-LDOPA NPs were found to be stable in the phosphate-buffered saline, saline medium, and minimal essential medium and formed aggregates of sizes smaller than 120 nm. All samples were found to be superparamagnetic in nature and the highest saturation magnetization was obtained for the Fe3O4-LDOPA samples. These NPs can bind to polymers such as PEG, and to fluorescent and chelating agents owing to the presence of free -NH2 or -COOH groups on the surface of NPs, allowing their use in dual imaging applications.

  9. Iron isotopic fractionation factor between magnetite and hydrous silicic melt

    NASA Astrophysics Data System (ADS)

    Huang, F.; Lundstrom, C. C.

    2006-12-01

    A "thermal migration" experiment was conducted in the piston cylinder to investigate the changes in composition of a wet andesitic bulk composition in a temperature gradient at 0.5 GPa. A homogeneous andesite powder (AGV-1 containing 4 wt.% H2O was sealed in a AuPd double capsule with the hot end at 950°C and the bottom end 350°C for 66 days. The charge changes from 100% melt at the top to the progressively more crystalline with the sequential appearance of apatite, magnetite, amphibole, biotite, plagioclase, quartz, and K-feldspar. We microdrilled 5 samples along the temperature gradient and analyzed these for Fe isotope ratios by double spike MC-ICP-MS at UIUC. Results show that the 100% melt area is depleted in heavy Fe isotopes relative to all more crystalline portions of the experiment (4 samples) with the offset in {δ}^{56/54}FeIRMM of about 1.7‰. This does not appear to reflect Fe loss in the experiment as the Fe content and isotopes mass balance and no detectable Fe was found in the capsule after the experiment. Instead the offset is interpreted to reflect the combination of diffusive fractionation of Fe moving by diffusion and possible equilibrium fractionations between melt and magnetite that occurs throughout the crystalline portion of the experiment. However, both the isotopic fractionation factor between magnetite and melt and the effect of diffusion on Fe isotopes remains unknown. We are currently investigating Fe isotopic fractionation factor between magnetite and melt and effects of melt diffusion on Fe isotopes. To assess diffusion, we will microdrill and analyze melt-melt diffusion couples from Lundstrom(G-Cubed, 2003). To assess magnetite-melt fractionation, we have begun piston cylinder experiments at 0.5 GPa and 800°C using a starting material synthesized based on the melt composition within the thermal migration experiment. Initial experiments produce a layer of 100% melt on top of a 2-phase mush of magnetite-melt. This will allow

  10. Magnetic Separations with Magnetite: Theory, Operation, and Limitations

    SciTech Connect

    G. B. Cotten

    2000-08-01

    This dissertation documents the theory development and experimental plan followed to describe how a magnetite-based column under the influence of an external magnetic field functions as a magnetic separator. Theoretical simulations predict that weekly paramagnetic particles in the sub-micron range can be magnetically separated while diamagnetic particles as large as 2 microns in diameter may pass. Magnetite-based columns were evaluated as magnetically-controllable enhanced filtration devices. There was no evidence of enhanced filtration for diamagnetic particles by the magnetite-based bed. Magnetite-based magnetic separators have proven to be effective in specific laboratory experiments, indicating a potential feasibility for scale-up operations. Column media-filter type filtration effects indicate a magnetite-based column would not be suitable for treatment of a waste stream with a high diamagnetic solids content or high volume throughput requirements. Specific applications requiring removal of sub-micron para- or ferromagnetic particles under batch or Stokes flow conditions would be most applicable.

  11. Fabrication of chitosan-magnetite nanocomposite strip for chromium removal

    NASA Astrophysics Data System (ADS)

    Sureshkumar, Vaishnavi; Kiruba Daniel, S. C. G.; Ruckmani, K.; Sivakumar, M.

    2016-02-01

    Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan-magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15-30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan-magnetite nanocomposite strip from aqueous solution was evaluated using UV-visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan-magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.

  12. Functionalization of Magnetite Nanoparticles as Oil Spill Collector

    PubMed Central

    Atta, Ayman M.; Al-Lohedan, Hamad A.; Al-Hussain, Sami A.

    2015-01-01

    In the present study, a new magnetic powder based on magnetite can be used as a petroleum crude oil collector. Amidoximes based on rosin as a natural product can be prepared from a reaction between hydroxylamine and rosin/acrylonitrile adducts. The produced rosin amidoximes were used as capping agents for magnetite nanoparticles to prepare hydrophobic coated magnetic powders. A new class of monodisperse hydrophobic magnetite nanoparticles was prepared by a simple and inexpensive co-precipitation method. Iron ions and iodine were prepared by the reaction between ferric chloride and potassium iodide. The structure and morphology of magnetite capped with rosin amidoxime were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), zeta potential, thermogravimetric analysis (TGA) and dynamic light scattering (DLS). The magnetic properties were determined from vibrating sample magnetometer (VSM) analyses. These prepared magnetite nanoparticles were tested as bioactive nanosystems and their antimicrobial effects were investigated. The prepared nanomaterials were examined as a crude oil collector using magnetic fields. The results show promising data for the separation of the petroleum crude oil from aqueous solution in environmental pollution cleanup. PMID:25822876

  13. One-Step Synthesis of Highly Water-Soluble Magnetite ColloidalNanosrystals

    SciTech Connect

    Ge, J.P.; Hu, Y.X.; Biasini, M.; Dong, C.L.; Guo, J.-H.; Beyermann, W.P.; Yin, Y.

    2007-03-05

    A high-temperature solution-phase hydrolysis approach has been developed for the synthesis of colloidal magnetite nanocrystals with well-controlled size and size distribution, high crystallinity, and high water solubility. The synthesis was accomplished by the hydrolysis and reduction of iron(III) cations in diethylene glycol with a rapidly injected solution of sodium hydroxide at an elevated temperature. The high reaction temperature allows for control over size and size distribution and yields highly crystalline products. The superior water solubility is achieved by using a polyelectrolyte, that is, poly(acrylic acid) as the capping agent, the carboxylate groups of which partially bind to the nanocrystal surface and partially extend into the surrounding water. The direct synthesis of water-soluble nanocrystals eliminates the need for additional surface modification steps which are usually required for treating hydrophobic nanocrystals produced in nonpolar solvents through the widely recognized pyrolysis route. The abundant carboxylate groups on the nanocrystal surface allow further modifications, such as bioconjugation, as demonstrated by linking cysteamine to the particle surface. The monodisperse, highly water-soluble, superparamagnetic, and biocompatible magnetite nanocrystals should find immediate important biomedical applications.

  14. Hydrothermal Preparation of Apatite Composite with Magnetite or Anatase

    SciTech Connect

    Murakami, Setsuaki; Ishida, Emile H.; Ioku, Koji

    2006-05-15

    Microstructure designed porous hydroxyapatite (Ca10(PO4)6(OH)2) composites with magnetite (Fe3O4) particles or anatase (TiO2) dispersion were prepared by hydrothermal treatment. These composites had micro-pores of about 0.1-0.5 {mu}m in size. Magnetite / Hydroxyapatite composites should be suitable for medical treatment of cancer, especially in bones, because HA can bond to bones directly and magnetite can generate heat. They must be used for hyperthermia therapies of cancer in bones. Meanwhile, anatase / Hydroxyapatite composite should be suitable for environmental purification, because HA rod-shape particles expose the specific crystal face, which adsorbs organic contaminants and so on.

  15. Mesoporous silica magnetite nanocomposite synthesized by using a neutral surfactant

    NASA Astrophysics Data System (ADS)

    Souza, K. C.; Salazar-Alvarez, G.; Ardisson, J. D.; Macedo, W. A. A.; Sousa, E. M. B.

    2008-05-01

    Magnetite nanoparticles coated by mesoporous silica were synthesized by an alternative chemical route using a neutral surfactant and without the application of any functionalization method. The magnetite (Fe3O4) nanoparticles were prepared by precipitation from aqueous media, and then coated with mesoporous silica by using nonionic block copolymer surfactants as the structure-directing agents. The mesoporous SiO2-coated Fe3O4 samples were characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, N2 adsorption-desorption isotherms, transmission electron microscopy, 57Fe Mössbauer spectroscopy, and vibrating sample magnetometry. Our results revealed that the magnetite nanoparticles are completely coated by well-ordered mesoporous silica with free pores and stable (~8 nm thick) pore walls, and that the structural and magnetic properties of the Fe3O4 nanoparticles are preserved in the applied synthesis route.

  16. Nano-structured and functionalized surfaces for cytocompatibility improvement and bactericidal action.

    PubMed

    Slepicka, Petr; Kasalkova, Nikola Slepickova; Siegel, Jakub; Kolska, Zdenka; Bacakova, Lucie; Svorcik, Vaclav

    2015-11-01

    The field of material surface modification with the aim of biomaterial construction involves several approaches of treatments that allow the preparation of materials, which positively influence adhesion of cells and their proliferation and thus aid and improve tissue formation. Modified materials have a surface composition and morphology intended to interact with biological systems and cellular functions. Not only surface chemistry has an effect on material biological response, surface structures of different morphology can be constructed to guide a desirable biological outcome. Nano-patterned material surfaces have been tested with the aim of how surface geometry and physical properties on a micro- and nano-scale can affect cellular response and influence cell adhesion and proliferation. Biological functionality of solid state substrates was significantly improved by the irradiation of material with plasma discharge or laser treatment. Commonly used "artificial" polymers (e.g. polyethylene (PE), polystyrene (PS), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN)) and biopolymers (e.g. Poly-l-Lactic acid (PLLA), polymethylpentene (PMP)) were treated with aim of biocompatibility improvement. The treatment of polymer/biopolymer substrates leads to formation of ripple or wrinkle-like structures, supported also with heat treatment or other subsequent surface processing. Several types of chemically different substances (e.g. metal or carbon nano-particles, proteins) were grafted onto material surfaces or built into material structures by different processes. Surface physico-chemical properties (e.g. chemistry, charge, morphology, wettability, electrical conductivity, optical and mechanical properties) of treated surfaces were determined. The enhancement of adhesion and proliferation of cells on modified substrates was investigated in vitro. Bactericidal action of noble metal nano-particles (e.g. Au, Ag) on polymers was

  17. Arsenic chemistry with sulfide, pyrite, zero-valent iron, and magnetite

    NASA Astrophysics Data System (ADS)

    Sun, Fenglong

    The aim of this thesis is to study the immobilization reactions of arsenic in water. Since compounds containing iron or sulfide are common in most natural and engineered systems, the research focused on the redox reactions and adsorption of arsenic with sulfide, pyrite, zero-valent iron (ZVI), and magnetite which were studied through wet chemistry methods and spectroscopic techniques. The kinetic and thermodynamic information of the reactions of As(V) with S(-II), As(V)/As(III) with pyrite and surface-oxidized pyrite, As(V) with ZVI and acid-treated ZVI, As(III) with magnetite was used to identify mechanisms. The necessity to maintain strictly anoxic conditions was emphasized for the study of arsenic redox chemistry with sulfides and ZVI. The major findings of this research can be stated as follows. First, dissolved sulfide reduced As(V) to lower valences to form a yellow precipitate at acidic pH. The reaction involved the formation of thioarsenic intermediate species. Dissolved O2, granular activated carbon (GAC) and dissolved Fe(II) inhibited the removal of As(V) by sulfide. Elemental sulfur catalyzed the reduction of As(V) by sulfide, which implied the possible benefit of using sulfur-loaded GAC for arsenic removal. Possible reaction mechanisms were discussed. Second, As(III) adsorbed on pristine pyrite over a broader pH range than on surface-oxidized pyrite, while As(V) adsorbed over a narrower pH range with pristine pyrite. As(V) was completely reduced to As(III) on pristine pyrite at acidic pH but not at higher pH. The reduction was first-order with respect to As(V). As(V) was not reduced on surface-oxidized pyrite at pH = 4--11. The different behaviors of As(V) and As(III) on pristine and surface oxidized pyrite determines the toxicity and mobility of arsenic under oxic/anoxic environments. Third, commercial ZVI reduced As(V) to As(III) at low pH (<9) but not at higher pH. Acid-treated ZVI reduced As(V) to As(0), indicated by wet chemical analyses and by

  18. Simple and Rapid Synthesis of Magnetite/Hydroxyapatite Composites for Hyperthermia Treatments via a Mechanochemical Route

    PubMed Central

    Iwasaki, Tomohiro; Nakatsuka, Ryo; Murase, Kenya; Takata, Hiroshige; Nakamura, Hideya; Watano, Satoru

    2013-01-01

    This paper presents a simple method for the rapid synthesis of magnetite/hydroxyapatite composite particles. In this method, superparamagnetic magnetite nanoparticles are first synthesized by coprecipitation using ferrous chloride and ferric chloride. Immediately following the synthesis, carbonate-substituted (B-type) hydroxyapatite particles are mechanochemically synthesized by wet milling dicalcium phosphate dihydrate and calcium carbonate in a dispersed suspension of magnetite nanoparticles, during which the magnetite nanoparticles are incorporated into the hydroxyapatite matrix. We observed that the resultant magnetite/hydroxyapatite composites possessed a homogeneous dispersion of magnetite nanoparticles, characterized by an absence of large aggregates. When this material was subjected to an alternating magnetic field, the heat generated increased with increasing magnetite concentration. For a magnetite concentration of 30 mass%, a temperature increase greater than 20 K was achieved in less than 50 s. These results suggest that our composites exhibit good hyperthermia properties and are promising candidates for hyperthermia treatments. PMID:23629669

  19. Magnetite solubility and phase stability in alkaline media at elevated temperatures

    SciTech Connect

    Ziemniak, S.E.; Jones, M.E.; Combs, K.E.S.

    1994-05-01

    Magnetite, Fe{sub 3}O{sub 4}, is the dominant oxide constituent of the indigenous corrosion layers that form on iron base alloys in high purity, high temperature water. The apparent simultaneous stability of two distinct oxidation states of iron in this metal oxide is responsible for its unique solubility behavior. The present work was undertaken to extend the experimental and theoretical bases for estimating solubilities of an iron corrosion product (Fe{sub 3}O{sub 4}/Fe(OH){sub 2}) over a broader temperature range and in the presence of complexing, pH-controlling reagents. These results indicate that a surface layer of ferrous hydroxide controls magnetite solubility behavior at low temperatures in much the same manner as a surface layer of nickel(II) hydroxide was previously reported to control the low temperature solubility behavior of NiO. The importance of Fe(III) ion complexes implies not only that most previously-derived thermodynamic properties of the Fe(OH){sub 3}{sup {minus}} ion are incorrect, but that magnetite phase stability probably shifts to favor a sodium ferric hydroxyphosphate compound in alkaline sodium phosphate solutions at elevated temperatures. The test methodology involved pumping alkaline solutions of known composition through a bed of Fe{sub 3}O{sub 4} granules and analyzing the emerging solution for Fe. Two pH-controlling reagents were tested: sodium phosphate and ammonia. Equilibria for the following reactions were described in thermodynamic terms: (a) Fe(OH){sub 2}/Fe{sub 3}O{sub 4} dissolution and transformation, (b) Fe(II) and Fe(III) ion hydroxocomplex formation (hydrolysis), (c) Fe(II) ion amminocomplex formation, and (d) Fe(II) and Fe(III) ion phosphatocomplex formation. 36 refs.

  20. Dried calcium alginate/magnetite spheres: a new support for chromatographic separations and enzyme immobilization

    SciTech Connect

    Burns, M.A.; Kvesitadze, G.I.; Graves, D.J.

    1985-02-01

    Dried spheres made from an alginate solution containing magnetite particles have excellent potential as a support for enzyme immobilization and chromatographic applications. The beads were found to be much stronger than gels such as polyacrylamide and dextran, indicating that high flow rates and pressures could be used in column separations. The support withstood not only temperatures of up to 120/sup 0/C, but also most pH values and common solvents. While some solutions, such as phosphate buffers, dissolved the spheres, stabilization with Tyzor TE eliminated this problem. The physical properties of the beads include a glasslike density of 2.2 g/mL, excellent sphericity, low porosity, and a narrow size distribution. The magnetite present in the support allows the beads to be used for magnetic separations such as high gradient magnetic filtration. Their high degree of microroughness provides a large exposed surface area for enzyme and ligand binding. Mixed Actinomyces fradiae proteases and Aspergillus niger ..cap alpha..-amylase, two enzymes representative of classes which attack large substrates, were immobilized on the bead's surface with high activity and stability. A cyanuric dye which can be used in chromatographic applications (Cibacron Blue F3GA) was also readily coupled to the surface of this support with good yield.

  1. Structural, Magnetic and Microwave Absorption Characteristics of Ni0.5LixZn(0.5-x)Fe2O4 Nano-particles Prepared by Co-Precipitation Method

    NASA Astrophysics Data System (ADS)

    Rohadiana, D. N.; Jamal, Z. A. Z.; Jamaludin, S. B.; Bari, M. F.; Malek, M. F.; Meng, C. E.

    2011-12-01

    Synthesis of Ni0.5LixZn(0.5-x)Fe2O4 nano-particles were realized via co-precipitation method. X-ray diffractometer (XRD), vibrating sample magnetometer (VSM) and network analyzer measurements were performed on the samples to determine, respectively, the characteristics of the crystal structure, and the magnetic and microwave absorption properties of the samples. The XRD patterns showed that all the samples are of single phase spinel type ferrites without the presence of other phases. Patterns of decreasing lattice parameter and increasing crystallite size values were observed at increasing Li concentration. For the magnetic property, the saturation magnetization (Ms) was found to vary with increasing pattern at higher Li doping level. The microwave electromagnetic properties of the samples were studied at the frequency range of 8-15 GHz and the results showed the material has the potential to be an alternative microwave absorber. The results and mechanisms concerned are discussed.

  2. Formation of "Chemically Pure" Magnetite from Mg-Fe-Carbonates Implications for the Exclusively Inorganic Origin of Magnetite and Sulfides in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, Douglas W.; Lauer, H. V., Jr.; Morris, R. V.; Trieman, A. H.; McKay, G. A.

    2006-01-01

    Magnetite and sulfides in the black rims of carbonate globules in Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al. that they are biogenic in origin. However, exclusively inorganic (abiotic) processes are able to account for the occurrence of carbonate-sulfide-magnetite assemblages in the meteorite. We have previously precipitated chemically zoned and sulfide-bearing carbonate globules analogous to those in ALH84001 (at less than or equal to 150 C) from multiple fluxes of variable-composition Ca-Mg-Fe-CO2-S-H2O solutions. Brief heating of precipitated globules to approx. 470 C produced magnetite and pyrrhotite within the globules by thermal decomposition of siderite and pyrite, respectively. We have also shown that morphology of magnetite formed by inorganic thermal decomposition of Fe-rich carbonate is similar to the morphology of so-called biogenic magnetite in the carbonate globules of ALH84001. Magnetite crystals in the rims of carbonate globules in ALH84001 are chemically pure [Note: "Chemically pure" is defined here as magnetite with Mg at levels comparable or lower than Mg detected by [8] in ALH84001 magnetite]. A debate continues on whether or not chemically pure magnetite can form by the thermal decomposition of mixed Mg-Fe-carbonates that have formed under abiotic conditions. Thomas-Keprta et al. argue that it is not possible to form Mg-free magnetite from Mg-Fe-carbonate based on thermodynamic data. We previously suggested that chemically pure magnetite could form by the thermal decomposition of relatively pure siderite in the outer rims of the globules. Mg-Fe-carbonates may also thermally decompose under conditions conducive for formation of chemically pure magnetite. In this paper we show through laboratory experiments that chemically pure magnetite can form by an inorganic process from mixed Mg-Fe-carbonates.

  3. CoFe2O4 nano-particles functionalized with 8-hydroxyquinoline for dispersive solid-phase micro-extraction and direct fluorometric monitoring of aluminum in human serum and water samples.

    PubMed

    Abdolmohammad-Zadeh, Hossein; Rahimpour, Elaheh

    2015-06-30

    A simple dispersive solid-phase micro-extraction method based on CoFe2O4 nano-particles (NPs) functionalized with 8-hydroxyquinoline (8-HQ) with the aid of sodium dodecyl sulfate (SDS) was developed for separation of Al(III) ions from aqueous solutions. Al(III) ions are separated at pH 7 via complex formation with 8-HQ using the functionalized CoFe2O4 nano-particles sol solution as a dispersed solid-phase extractor. The separated analyte is directly quantified by a spectrofluorometric method at 370nm excitation and 506nm emission wavelengths. A comparison of the fluorescence of Al(III)-8-HQ complex in bulk solution and that of Al(III) ion interacted with 8-HQ/SDS/CoFe2O4 NPs revealed a nearly 5-fold improvement in intensity. The experimental factors influencing the separation and in situ monitoring of the analyte were optimized. Under these conditions, the calibration graph was linear in the range of 0.1-300ngmL(-1) with a correlation coefficient of 0.9986. The limit of detection and limit of quantification were 0.03ngmL(-1) and 0.10ngmL(-1), respectively. The inter-day and intra-day relative standard deviations for six replicate determinations of 150ngmL(-1) Al(III) ion were 2.8% and 1.7%, respectively. The method was successfully applied to direct determine Al(III) ion in various human serum and water samples.

  4. Nano silver and nano zinc-oxide in surface waters - exposure estimation for Europe at high spatial and temporal resolution.

    PubMed

    Dumont, Egon; Johnson, Andrew C; Keller, Virginie D J; Williams, Richard J

    2015-01-01

    Nano silver and nano zinc-oxide monthly concentrations in surface waters across Europe were modeled at ~6 x 9 km spatial resolution. Nano-particle loadings from households to rivers were simulated considering household connectivity to sewerage, sewage treatment efficiency, the spatial distribution of sewage treatment plants, and their associated populations. These loadings were used to model temporally varying nano-particle concentrations in rivers, lakes and wetlands by considering dilution, downstream transport, water evaporation, water abstraction, and nano-particle sedimentation. Temporal variability in concentrations caused by weather variation was simulated using monthly weather data for a representative 31-year period. Modeled concentrations represent current levels of nano-particle production.Two scenarios were modeled. In the most likely scenario, half the river stretches had long-term average concentrations exceeding 0.002 ng L(-1) nano silver and 1.5 ng L(-1) nano zinc oxide. In 10% of the river stretches, these concentrations exceeded 0.18 ng L(-1) and 150 ng L(-1), respectively. Predicted concentrations were usually highest in July.

  5. Iron site occupancies in magnetite-ulvospinel solid solution: A new approach using XMCD

    SciTech Connect

    Pearce, C. I.; Henderson, C. M. B.; Telling, N. D.; Pattrick, R. A.D.; Vaughan, D. J.; Charnock, J. M.; Arenholz, E.; Tuna, F.; Coker, V.S.; Laan, G. van der

    2009-06-22

    Ordering of Fe{sup 3+} and Fe{sup 2+} between octahedral (Oh) and tetrahedral (Td) sites in synthetic members of the magnetite (Fe{sub 3}O{sub 4}) - ulvoespinel (Fe{sub 2}TiO{sub 4}) solid-solution series was determined using Fe L{sub 2,3}-edge X-ray magnetic circular dichroism (XMCD) coupled with electron microprobe and chemical analysis, Ti L-edge spectroscopy, Fe K-edge EXAFS and XANES, Fe{sub 57} Moessbauer spectroscopy, and unit cell parameters. Microprobe analysis, cell edges and chemical FeO determinations showed that the bulk compositions of the samples were stoichiometric magnetite-ulvoespinel solid-solutions. Surface sensitive XMCD showed that the surfaces of these oxide minerals were more sensitive to redox conditions and some samples required re-equilibration with suitable solid-solid buffers. Detailed site-occupancy analysis of these samples gave XMCD-Fe{sup 2+}/Fe{sup 3+} ratios very close to stoichiometric values. L{sub 2,3}-edge spectroscopy showed that Ti{sup 4+} was restricted to Oh sites. XMCD results showed that significant Fe{sup 2+} only entered Td when the Ti content was > 0.40 apfu while Fe{sup 2+} in Oh increased from 1 a.p.f.u in magnetite to a maximum of {approx}1.4 apfu in USP45. As the Ti content increased from this point, the steady increase in Fe{sup 2+} in Td sites was clearly observable in the XMCD spectra, concurrent with a slow decrease in Fe{sup 2+} in Oh sites. Calculated magnetic moments showed a steady decrease from magnetite (4.06 {mu}{sub B}) to USP45 (1.5 {mu}{sub B}) and then a slower decrease towards the value for ulvoespinel (0 {mu}{sub B}). Two of the synthesized samples were also partially maghemitized by re-equilibrating with an oxidizing Ni-NiO buffer and XMCD showed that Fe{sup 2+} oxidation only occurred at Oh sites, with concomitant vacancy formation restricted to this site. This study shows the advantage of using XMCD as a direct measurement of Fe oxidation state in these complex magnetic spinels. These results

  6. Intracellular hyperthermia for cancer using magnetite cationic liposomes

    NASA Astrophysics Data System (ADS)

    Shinkai, Masashige; Yanase, Mitsugu; Suzuki, Masataka; Honda, Hiroyuki; Wakabayashi, Toshihiko; Yoshida, Jun; Kobayashi, Takeshi

    1999-04-01

    We have developed `magnetite cationic liposomes' (MCLs) as a new heating mediator for hyperthermia. The hyperthermic effect on solid glioma tissue grown subcutaneously in F344 rats was investigated. Complete tumor regression was observed in about 90% of the rats by three times of repeated heating. Furthermore, induction of antitumor immunity for T-9 rat glioma using MCLs was investigated.

  7. SEPARATION OF TECHNETIUM FROM AQUEOUS SOLUTIONS BY COPRECIPITATION WITH MAGNETITE

    DOEpatents

    Rimshaw, S.J.

    1961-10-24

    A method of separating technetium in the 4+ oxidation state from an aqueous basic solution containing products of uranium fission is described. The method consists of contacting the solution with finely divided magnetite and recovering a technetium-bearing precipitate. (AEC)

  8. Avian magnetite-based magnetoreception: a physiologist's perspective

    PubMed Central

    Cadiou, Hervé; McNaughton, Peter A.

    2010-01-01

    It is now well established that animals use the Earth's magnetic field to perform long-distance migration and other navigational tasks. However, the transduction mechanisms that allow the conversion of magnetic field variations into an electric signal by specialized sensory cells remain largely unknown. Among the species that have been shown to sense Earth-strength magnetic fields, birds have been a model of choice since behavioural tests show that their direction-finding abilities are strongly influenced by magnetic fields. Magnetite, a ferromagnetic mineral, has been found in a wide range of organisms, from bacteria to vertebrates. In birds, both superparamagnetic (SPM) and single-domain magnetite have been found to be associated with the trigeminal nerve. Electrophysiological recordings from cells in the trigeminal ganglion have shown an increase in action potential firing in response to magnetic field changes. More recently, histological evidence has demonstrated the presence of SPM magnetite in the subcutis of the pigeon's upper beak. The aims of the present review are to review the evidence for a magnetite-based mechanism in birds and to introduce physiological concepts in order to refine the proposed models. PMID:20106875

  9. Clay and Magnetite Formation at Yellowknife Bay, Mars

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2014-09-01

    Sheepbed mudstone contains a clay-magnetite assemblage formed by dissolution of approximately 70% amorphous phase, 20% olivine, 10% host rock mixture, by a pore fluid at moderate W/R ratio. The clay is similar to Lafayette's ferric saponite and gel.

  10. Enhancing of Fe removal in pyrophyllite using magnetite ore susceptor

    NASA Astrophysics Data System (ADS)

    Hack Lim, Dae; Myung, Eun Ji; Kim, Hyun Soo; Choul Choi, Nag; Cho, Kang Hee; Park, Cheon Young

    2016-04-01

    Pyrite and hematite are an impurity that reduces the grade of pyrophyllite in the final products. Because the impurity in pyrophyllite which was associated with hydrothermally altered rocks. Microwave has been extensively explored in various fields of materials processing. This technology exhibits unique characteristics including volumetric and selective heating, which eventually lead to many exceptional advantages over conventional processing methods including both energy and cost savings, improved product quality and faster processing. The aim of this study was to investigate the application possibility of microwave process for Fe removal in pyrophyllite. The pyrite and quartz of the pyrophyllite was determined by reflected light microscopy and XRD. The result of Fe removal experiment in pyrophyllite using microwave susceptor(magnetite ore included ilmenite and magnetite) showed to decrease of Fe content in pyrophyllite. The Fe removal of 93.62% and parameters were obtained under the following conditions by magnetite ore was 20.0 g, the pyrophyllite was 10.0 g, and the microwave heating time was 10.0 min. By means of microwave, Fe removal in pyrophyllite can be rapidly and efficiently pyrolyze. if some of the magnetite ore, which acts as a microwave susceptor, is mixed with the raw material. Acknowledgment : This subject is supported by Korea Ministry of Environment as "Advanced Technology Program for Environmental Industry"

  11. Synthesis of a stable magnetite (magnetic fluid) colloid solution

    NASA Astrophysics Data System (ADS)

    Evdokimov, S. I.; Evdokimov, V. S.

    2017-01-01

    The article is dedicated to the development and investigation of conditions for obtaining the aggregate stable colloid solutions of magnetite – magnetic fluids. The developed method differs from the known ones and involves new ways of producing and stabilizing magnetic nanoparticles with a narrow particle size distribution.

  12. Scale-up of the production of highly reactive biogenic magnetite nanoparticles using Geobacter sulfurreducens.

    PubMed

    Byrne, J M; Muhamadali, H; Coker, V S; Cooper, J; Lloyd, J R

    2015-06-06

    Although there are numerous examples of large-scale commercial microbial synthesis routes for organic bioproducts, few studies have addressed the obvious potential for microbial systems to produce inorganic functional biomaterials at scale. Here we address this by focusing on the production of nanoscale biomagnetite particles by the Fe(III)-reducing bacterium Geobacter sulfurreducens, which was scaled up successfully from laboratory- to pilot plant-scale production, while maintaining the surface reactivity and magnetic properties which make this material well suited to commercial exploitation. At the largest scale tested, the bacterium was grown in a 50 l bioreactor, harvested and then inoculated into a buffer solution containing Fe(III)-oxyhydroxide and an electron donor and mediator, which promoted the formation of magnetite in under 24 h. This procedure was capable of producing up to 120 g of biomagnetite. The particle size distribution was maintained between 10 and 15 nm during scale-up of this second step from 10 ml to 10 l, with conserved magnetic properties and surface reactivity; the latter demonstrated by the reduction of Cr(VI). The process presented provides an environmentally benign route to magnetite production and serves as an alternative to harsher synthetic techniques, with the clear potential to be used to produce kilogram to tonne quantities.

  13. Laser spectroscopy of finite size and covering effects in magnetite nanoparticles

    NASA Astrophysics Data System (ADS)

    Nikiforov, V. N.; Ignatenko, A. N.; Ivanov, A. V.; Irkhin, V. Yu

    2016-02-01

    Experiments on the impact of the size of magnetite clusters on various magnetic properties (magnetic moment, Curie temperature, blocking temperature etc) have been carried out. The methods of magnetic separation and centrifugation of water suspensions of biocompatible iron oxide nanoparticles (NPs) allow one to produce fractions with diameters of nanoparticles in the range of 4-22 nm. The size of the NPs is controlled by the methods of dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). For the first time the DLS method is applied in real time to control the size during the process of the separation of the NPs in aqueous suspensions. The changes of the size of NPs cause a shift in the Curie temperature and changes in the specific magnetic properties of the iron NPs. The experimental data is interpreted on the basis of Monte Carlo simulations for the classical Heisenberg model with different bulk and surface magnetic moments. It is demonstrated experimentally and by theoretical modeling that the magnetic properties of magnetite NPs are determined not only by their sizes, but also by their surface spin states, while both growing and falling dependences of the magnetic moment (per Fe3O4 formula unit) are possible, depending on the number of magnetic atoms in the nanoparticle. NPs that are both clean and covered with bioresorbable layer clusters have been investigated.

  14. Preparation and characterization of chondroitin-sulfate-A-coated magnetite nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Tóth, Ildikó Y.; Illés, Erzsébet; Szekeres, Márta; Tombácz, Etelka

    2015-04-01

    Polysaccharides are promising candidates for manufacturing biocompatible core-shell nanoparticles with potential in vivo use. Superparamagnetic magnetite nanoparticles (MNPs) have prospective application in both diagnosis and therapy, and so developing a novel polysaccharide shell on MNP core is of great challenge. MNPs were prepared by co-precipitation, then the surface of purified MNPs was coated with chondroitin-sulfate-A (CSA) to obtain core-shell structured magnetite nanoparticles (CSA@MNP). The effect of the added amount of CSA on the surface charging and the aggregation state of MNPs at various pHs and 10 mM NaCl was measured by electrophoresis and dynamic light scattering. The amphoteric behavior of MNPs was fundamentally modified by adsorption of CSA polyanions. A very low CSA-loading induces the aggregation of MNPs, while four times more stabilizes the dispersions over the whole pH-range studied. The coagulation kinetics experiments measured at pH=6.3±0.3 showed that salt tolerance of CSA@MNPs rises up to ~150 mM NaCl.

  15. P-recovery by secondary nucleation and growth of calcium phosphates on magnetite mineral.

    PubMed

    Karapinar, Nuray; Hoffmann, Erhard; Hahn, Hermann H

    2006-03-01

    Precipitation of calcium phosphates from supersaturated solutions seeded with magnetite powder (magnetite mineral, Fe3O4) has been studied in lab scale in the pH range 6.9-7.7. While the initial concentration of phosphorus was 1.29 mmol/l, the initial molar ratio of Ca/P was taken one to three times of the stoichiometric calcium to phosphorus ratio of hydroxyapatite. To bring out the secondary nucleation, the precipitation system was allowed to relax and pH of the solution was maintained at the initially preset value. The period before base was added for the first time during relaxation was defined as lagtime and sodium hydroxide added during the relaxation was evaluated as the degree of growth. The lagtime was found to be dependent on the solution pH, therefore on the initial amount of precipitation. Coverage of seed surface by heterogeneous nucleation is essential. Since all precipitation by secondary nucleation took place on the seed material, precipitation during relaxation was due to growth of the solid phase on the seed surfaces. It was found that there was a pH range in which growth rate was directly proportional to pH. However, at lower residual concentrations of phosphorus, despite relatively higher pH, the growth rate was decreased.

  16. Size Effects in Epitaxial Films of Magnetite

    DTIC Science & Technology

    2002-06-03

    achieve an autocompensated Fe30O4(001) surface that possesses the observed (ý 2X S() "Vý)R45° symmetry is to terminate it with a half tetra- 2 hedral Fe3...Transition Metal Oxides: Surface Chemistry and Catalysis, Elsevier, Amsterdam, 1989. •104 [3] P. Marcus, V. Maurice, in: K.E. Heusler (Ed.), Passivation of

  17. Abiotic reductive dechlorination of chlorinated ethylenes by iron-bearing soil minerals. 1. Pyrite and magnetite.

    PubMed

    Lee, Woojin; Batchelor, Bill

    2002-12-01

    Abiotic reductive dechlorination of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (cis-DCE), and vinyl chloride (VC)) by pyrite and magnetite was characterized in a batch reactor system. Dechlorination kinetics was adequately described by a modified Langmuir-Hinshelwood model that includes the effect of a decreasing reductive capacity of soil mineral. The kinetic rate constant for the reductive dechlorination of target organics at reactive sites of soil minerals was in the range of 0.185 (+/- 0.023) to 1.71 (+/- 0.06) day(-1). The calculated specific reductive capacity of soil minerals for target organics was in the range of 0.33 (+/- 0.02) to 2.26 (+/- 0.06) microM/g and sorption coefficient was in the range of 0.181 (+/- 0.006) to 0.7 (+/- 0.022) mM(-1). Surface area-normalized pseudo-first-order initial rate constants for target organics by pyrite were found to be 23.5 to 40.3 times greater than those by magnetite. Target organics were mainly transformed to acetylene and small amount of chlorinated intermediates, which suggests that beta-elimination was the main dechlorination pathway. The dechlorination of VC followed a hydrogenolysis pathway to produce ethylene and ethane. The addition of Fe(II) increased the dechlorination rate of cis-DCE and VC in magnetite suspension by nearly a factor of 10. The results obtained in this research provide basic knowledge to better predict the fate of chlorinated ethylenes and to understand the potential of abiotic processes in natural attenuation.

  18. Biophysics of Magnetic Orientation: Radical Pairs, Biogenic Magnetite, or both?

    NASA Astrophysics Data System (ADS)

    Kirschvink, Joe

    2011-03-01

    Two major biophysical mechanisms for magnetoreception in terrestrial animals, one based on biogenic magnetite and another on radical-pair biochemical reactions, have been the subject of experiment and debate for the past 30 years. The magnetite hypothesis has stood the test of time: biogenic magnetite is synthesized biochemically in Bacteria, Protists, and numerous Animal phyla, as well as in some plants. Chains of single-domain crystals have been detected by clean-lab based SQUID magnetometry in animal tissues in all major phyla, followed by high-resolution TEM in selected model organisms, as well as by electrophysiological studies demonstrating the role of the ophthalmic branch of the trigeminal nerve in the magnetoreceptive process. Pulse-remagnetization - configured to uniquely flip the polarity of single-domain ferromagnets - has dramatic effects on the behavior of many birds, honeybees, mole rats, turtles, and bats, to cite a growing list. Magnetite-containing cells in the vicinity of these neurons in fish are now the subject of intense study by our consortium. The existence of a specialized class of magnetite-containing magnetoreceptor cells in animal tissues is no longer controversial. In contrast, less success has been achieved in gaining experimental support across a range of taxa for the radical-pair hypothesis. Although this mechanism was proposed to explain an early observation that birds would not respond to complete inversion of the magnetic vector, many organisms (even some birds) do indeed respond to the field polarity. We also note that few, if any, of these critical experiments have been done using fully double-blind methods. This is joint work with: M. M. Walker (University of Auckland, New Zealand) and M. Winklhofer (LMU Munich, Germany).

  19. Low-temperature oxidation of magnetite - a humidity sensitive process?

    NASA Astrophysics Data System (ADS)

    Appel, Erwin; Fang, Xiaomin; Herb, Christian; Hu, Shouyun

    2015-04-01

    Extensive multi-parameter palaeoclimate records were obtained from two long-term lacustrine archives at the Tibetan Plateau: the Qaidam basin (2.69-0.08 Ma) and Heqing basin (0.90-0.03 Ma). At present the region of the Qaidam site has an arid climate (<100 mm mean annual precipitation) while the Heqing site is located in the sub-tropical region with monsoonal rainfall. Magnetic properties play a prominent role for palaeoclimate interpretation in both records. Several parameters show a 100 kyr eccentricity cyclicity; in the Qaidam record also the Mid-Pleistocene Transition is seen. Both magnetic records are controlled by different absolute and relative contributions of magnetite and its altered (maghemitized) phases as well as hematite. Weathering conditions likely cause a systematic variation of magnetic mineralogy due to low-temperature oxidation (LTO). Maghemitization is well recognized as an alteration process in submarine basalts but about its relevance for climate-induced weathering in continental environments little is known. Various factors i.e., humidity, temperature, seasonality, duration of specific weathering conditions, and bacterial activity could be responsible for maghemitization (LTO) and transformation to hematite (or goethite) when a critical degree of LTO is reached. These factors may lead to a complex interplay, but one has to note that water acts as an electrolyte for Fe(II) to Fe(III) oxidation at the crystal surface and due to maghemitization-induced lattice shrinking a larger internal particle surface area becomes exposed to oxidation. We suggest that humidity is the most crucial driver for the two studied archives - for the following reasons: (1) The overall parameter variations and catchment conditions are well in agreement with an LTO scenario. (2) In the Qaidam record we observe a direct relationship of a humidity sensitive pollen Ratio with magnetic susceptibility (reflecting the degree of alteration by LTO). (3) In the Heqing record

  20. Formation of tabular single-domain magnetite induced by Geobacter metallireducens GS-15

    PubMed Central

    Vali, Hojatollah; Weiss, Benjamin; Li, Yi-Liang; Sears, S. Kelly; Kim, Soon Sam; Kirschvink, Joseph L.; Zhang, Chuanlun L.

    2004-01-01

    Distinct morphological characteristics of magnetite formed intracellularly by magnetic bacteria (magnetosome) are invoked as compelling evidence for biological activity on Earth and possibly on Mars. Crystals of magnetite produced extracellularly by a variety of bacteria including Geobacter metallireducens GS-15, thermophilic bacteria, and psychrotolerant bacteria are, however, traditionally not thought to have nearly as distinct morphologies. The size and shape of extracellular magnetite depend on the culture conditions and type of bacteria. Under typical CO2-rich culture conditions, GS-15 is known to produce superparamagnetic magnetite (crystal diameters of approximately <30 nm). In the current study, we were able to produce a unique form of tabular, single-domain magnetite under nontraditional (low-CO2) culture conditions. This magnetite has a distinct crystal habit and magnetic properties. This magnetite could be used as a biosignature to recognize ancient biological activities in terrestrial and extraterrestrial environments and also may be a major carrier of the magnetization in natural sediments. PMID:15525704

  1. High-Temperature Magnetism as a Probe for Structural and Compositional Uniformity in Ligand-Capped Magnetite Nanoparticles

    PubMed Central

    2015-01-01

    To investigate magnetostructural relationships in colloidal magnetite (Fe3O4) nanoparticles (NPs) at high temperature (300–900 K), we measured the temperature dependence of magnetization (M) of oleate-capped magnetite NPs ca. 20 nm in size. Magnetometry revealed an unusual irreversible high-temperature dependence of M for these NPs, with dip and loop features observed during heating–cooling cycles. Detailed characterizations of as-synthesized and annealed Fe3O4 NPs as well as reference ligand-free Fe3O4 NPs indicate that both types of features in M(T) are related to thermal decomposition of the capping ligands. The ligand decomposition upon the initial heating induces a reduction of Fe3+ to Fe2+ and the associated dip in M, leading to more structurally and compositionally uniform magnetite NPs. Having lost the protective ligands, the NPs continually sinter during subsequent heating cycles, resulting in divergent M curves featuring loops. The increase in M with sintering proceeds not only through elimination of a magnetically dead layer on the particle surface, as a result of a decrease in specific surface area with increasing size, but also through an uncommonly invoked effect resulting from a significant change in Fe3+/Fe2+ ratio with heat treatment. The interpretation of irreversible features in M(T) indicates that reversible M(T) behavior, conversely, can be expected only for ligand-free, structurally and compositionally uniform magnetite NPs, suggesting a general applicability of high-temperature M(T) measurements as an analytical method for probing the structure and composition of magnetic nanomaterials. PMID:25506407

  2. Magnetite: What it reveals about the origin of the banded iron formations. [Abstract only

    NASA Technical Reports Server (NTRS)

    Schwartz, D. E.; Mancinelli, R. L.; White, M. R.

    1994-01-01

    Magnetite, Fe3O4 is produced abiotically and biotically. Abiotically, magnetite is a late magmatic mineral and forms as a consequence of the cooling of iron rich magma. Biotically, magnetite is produced by several organisms, including magnetotactic bacteria. Hematite, Fe2O3, is also produced abiotically and biotically. Abiotically, hematite rarely occurs as a primary mineral in igneous rocks, but is common as an alteration product, fumarole deposit, and in some metamorphosed Fe-rich rocks. Biotically, hematite is produced by several types of microorganisms. Biologically-produced magnetite and hematite are formed under the control of the host organism, and consequently, have characteristics not found in abiotically produced magnetite and hematite crystals. To determine if the magnetite and hematite in the Banded Iron Formation was biologically or abiotically produced, the characteristics of biologically-produced magnetite and hematite (concentrated from Aquaspirillum magnetotacticum) and abiotically-produced magnetite and hematite obtained from Wards Scientific Supply Company, were compared with characteristics of magnetite and hematite concentrated from the Gunflint Banded Iron Formation (Ontario, Canada) using thermal and crystallographic analytical techniques. Whole rock analysis of the Gunflint Banded Iron Formation by x-ray diffraction (XRD) and differential thermal analysis (DTA) revealed the presence of quartz, hematite, siderite and dolomite as the major minerals, and magnetite, greenalite, pyrite, pyrrhotite and apatite as the minor minerals. Analysis of a crude magnetic fraction of the Gunflint showed the minerals quartz, hematite, siderite, dolomite, and magnetite. Analysis of the crude magnetic fraction from Aquaspirillum magnetotacticum revealed organic compounds plus hematite and magnetite. The mineral identification and particle size distribution data obtained from the DTA along with XRD data indicate that the magnetite and hematite from the Gunflint

  3. From iron(III) precursor to magnetite and vice versa

    SciTech Connect

    Gotic, M.; Jurkin, T.; Music, S.

    2009-10-15

    The syntheses of nanosize magnetite particles by wet-chemical oxidation of Fe{sup 2+} have been extensively investigated. In the present investigation the nanosize magnetite particles were synthesised without using the Fe(II) precursor. This was achieved by {gamma}-irradiation of water-in-oil microemulsion containing only the Fe(III) precursor. The corresponding phase transformations were monitored. Microemulsions (pH {approx} 12.5) were {gamma}-irradiated at a relatively high dose rate of {approx}22 kGy/h. Upon 1 h of {gamma}-irradiation the XRD pattern of the precipitate showed goethite and unidentified low-intensity peaks. Upon 6 h of {gamma}-irradiation, reductive conditions were achieved and substoichiometric magnetite ({approx}Fe{sub 2.71}O{sub 4}) particles with insignificant amount of goethite particles found in the precipitate. Hydrated electrons (e{sub aq}{sup -}), organic radicals and hydrogen gas as radiolytic products were responsible for the reductive dissolution of iron oxide in the microemulsion and the reduction Fe{sup 3+} {yields} Fe{sup 2+}. Upon 18 h of {gamma}-irradiation the precipitate exhibited dual behaviour, it was a more oxidised product than the precipitate obtained after 6 h of {gamma}-irradiation, but it contained magnetite particles in a more reduced form ({approx}Fe{sub 2.93}O{sub 4}). It was presumed that the reduction and oxidation processes existed as concurrent competitive processes in the microemulsion. After 18 h of {gamma}-irradiation the pH of the medium shifted from the alkaline to the acidic range. The high dose rate of {approx}22 kGy/h was directly responsible for this shift to the acidic range. At a slightly acidic pH a further reduction of Fe{sup 3+} {yields} Fe{sup 2+} resulted in the formation of more stoichiometric magnetite particles, whereas the oxidation conditions in the acidic medium permitted the oxidation Fe{sup 2+} {yields} Fe{sup 3+}. The Fe{sup 3+} was much less soluble in the acidic medium and it hydrolysed

  4. Mineral chemistry of magnetite from magnetite-apatite mineralization and their host rocks: examples from Kiruna, Sweden, and El Laco, Chile

    NASA Astrophysics Data System (ADS)

    Broughm, Shannon G.; Hanchar, John M.; Tornos, Fernando; Westhues, Anne; Attersley, Samuel

    2017-03-01

    Interpretation of the mineralizing environment of magnetite-apatite deposits remains controversial with theories that include a hydrothermal or magmatic origin or a combination of those two processes. To address this controversy, we have analyzed the trace element content of magnetite from precisely known geographic locations and geologic environments from the Precambrian magnetite-apatite ore and host rocks in Kiruna, Sweden, and the Pliocene-Holocene El Laco volcano in the Atacama desert of Chile. Magnetite samples from Kiruna have low trace element concentrations with little chemical variation between the ore, host, and related intrusive rocks. Magnetite from andesite at El Laco, and dacite from the nearby Láscar volcano, has high trace element concentrations typical of magmatic magnetite. El Laco ore magnetite have low trace element concentrations and displays growth zoning in incompatible elements (Si, Ca, and Ce), compatible elements (Mg, Al, and Mn), large-ion lithophile element (Sr), and high field strength element (Y, Nb, and Th). The El Laco ore magnetite are similar in composition to magnetite that has been previously interpreted to have crystallized from hydrothermal fluids; however, there is a significant difference in the internal zoning patterns. At El Laco, each zoned element is either enriched or depleted in the same layers, suggesting the magnetite crystallized from a volatile-rich, iron-oxide melt. In general, the compositions of magnetite from these two deposits plot in very wide fields that are not restricted to the proposed fields in published discriminant diagrams. This suggests that the use of these diagrams and genetic models based on them should be used with caution.

  5. Nano silver and nano zinc-oxide in surface waters – Exposure estimation for Europe at high spatial and temporal resolution

    PubMed Central

    Dumont, Egon; Johnson, Andrew C.; Keller, Virginie D.J.; Williams, Richard J.

    2015-01-01

    Nano silver and nano zinc-oxide monthly concentrations in surface waters across Europe were modeled at ∼6 × 9 km spatial resolution. Nano-particle loadings from households to rivers were simulated considering household connectivity to sewerage, sewage treatment efficiency, the spatial distribution of sewage treatment plants, and their associated populations. These loadings were used to model temporally varying nano-particle concentrations in rivers, lakes and wetlands by considering dilution, downstream transport, water evaporation, water abstraction, and nano-particle sedimentation. Temporal variability in concentrations caused by weather variation was simulated using monthly weather data for a representative 31-year period. Modeled concentrations represent current levels of nano-particle production. Two scenarios were modeled. In the most likely scenario, half the river stretches had long-term average concentrations exceeding 0.002 ng L−1 nano silver and 1.5 ng L−1 nano zinc oxide. In 10% of the river stretches, these concentrations exceeded 0.18 ng L−1 and 150 ng L−1, respectively. Predicted concentrations were usually highest in July. PMID:25463731

  6. A density functional theory investigation of the electronic structure and spin moments of magnetite.

    PubMed

    Noh, Junghyun; Osman, Osman I; Aziz, Saadullah G; Winget, Paul; Brédas, Jean-Luc

    2014-08-01

    We present the results of density functional theory (DFT) calculations on magnetite, Fe3O4, which has been recently considered as electrode in the emerging field of organic spintronics. Given the nature of the potential applications, we evaluated the magnetite room-temperature cubic [Formula: see text] phase in terms of structural, electronic, and magnetic properties. We considered GGA (PBE), GGA + U (PBE + U), and range-separated hybrid (HSE06 and HSE(15%)) functionals. Calculations using HSE06 and HSE(15%) functionals underline the impact that inclusion of exact exchange has on the electronic structure. While the modulation of the band gap with exact exchange has been seen in numerous situations, the dramatic change in the valence band nature and states near the Fermi level has major implications for even a qualitative interpretation of the DFT results. We find that HSE06 leads to highly localized states below the Fermi level while HSE(15%) and PBE + U result in delocalized states around the Fermi level. The significant differences in local magnetic moments and atomic charges indicate that describing room-temperature bulk materials, surfaces and interfaces may require different functionals than their low-temperature counterparts.

  7. A density functional theory investigation of the electronic structure and spin moments of magnetite

    PubMed Central

    Noh, Junghyun; Osman, Osman I; Aziz, Saadullah G; Winget, Paul; Brédas, Jean-Luc

    2014-01-01

    We present the results of density functional theory (DFT) calculations on magnetite, Fe3O4, which has been recently considered as electrode in the emerging field of organic spintronics. Given the nature of the potential applications, we evaluated the magnetite room-temperature cubic phase in terms of structural, electronic, and magnetic properties. We considered GGA (PBE), GGA + U (PBE + U), and range-separated hybrid (HSE06 and HSE(15%)) functionals. Calculations using HSE06 and HSE(15%) functionals underline the impact that inclusion of exact exchange has on the electronic structure. While the modulation of the band gap with exact exchange has been seen in numerous situations, the dramatic change in the valence band nature and states near the Fermi level has major implications for even a qualitative interpretation of the DFT results. We find that HSE06 leads to highly localized states below the Fermi level while HSE(15%) and PBE + U result in delocalized states around the Fermi level. The significant differences in local magnetic moments and atomic charges indicate that describing room-temperature bulk materials, surfaces and interfaces may require different functionals than their low-temperature counterparts. PMID:27877697

  8. Self-organization of magnetite nanoparticles in providing Saccharomyces cerevisiae Yeasts with magnetic properties

    NASA Astrophysics Data System (ADS)

    Gorobets, S. V.; Yu, Gorobets O.; Demianenko, I. V.; Nikolaenko, R. N.

    2013-07-01

    The compared analyze of four methods of the magnetic nanoparticles clusters parameters estimation were developed and performed, such as, method, which takes into account two magneto-force scans of surface for calculation, geometry distance measurement between two centers of clusters in chains using the functions of NOVA-program, which is the standard computer equipment for scanning probe microscopy SOLVER PRO-M and the model, which takes into account the table meaning of magnetite magnetization and atomic-force microscopy. The magnetically-controllable biosorbent based on the culture of Saccharomyces cerevisiae was used as a model object for adequacy analyze of these models. As the result of the work we get the information about the depth of clusters penetration inside biomembrane, the typical sizes of clusters and the dispersion of magnetic clusters sizes. This analyze shows that all four methods can be used for single magnetic clusters, but for clusters, which lay in chains with small distance between their centers, the mode, which takes into account the table meaning of magnetite magnetization, cannot be used, because this model does not take into account the nearest neighbors contribution of interaction of magnetic fields dipole with magnetic probe.

  9. Size-dependent reactivity of magnetite nanoparticles: a field-laboratory comparison

    USGS Publications Warehouse

    Swindle, Andrew L.; Elwood Madden, Andrew S.; Cozzarelli, Isabelle M.; Benamara, Mourad

    2014-01-01

    Logistic challenges make direct comparisons between laboratory- and field-based investigations into the size-dependent reactivity of nanomaterials difficult. This investigation sought to compare the size-dependent reactivity of nanoparticles in a field setting to a laboratory analog using the specific example of magnetite dissolution. Synthetic magnetite nanoparticles of three size intervals, ∼6 nm, ∼44 nm, and ∼90 nm were emplaced in the subsurface of the USGS research site at the Norman Landfill for up to 30 days using custom-made subsurface nanoparticle holders. Laboratory analog dissolution experiments were conducted using synthetic groundwater. Reaction products were analyzed via TEM and SEM and compared to initial particle characterizations. Field results indicated that an organic coating developed on the particle surfaces largely inhibiting reactivity. Limited dissolution occurred, with the amount of dissolution decreasing as particle size decreased. Conversely, the laboratory analogs without organics revealed greater dissolution of the smaller particles. These results showed that the presence of dissolved organics led to a nearly complete reversal in the size-dependent reactivity trends displayed between the field and laboratory experiments indicating that size-dependent trends observed in laboratory investigations may not be relevant in organic-rich natural systems.

  10. Hybrid nanomaterials based on gum Arabic and magnetite for hyperthermia treatments.

    PubMed

    Horst, M Fernanda; Coral, Diego F; Fernández van Raap, Marcela B; Alvarez, Mariana; Lassalle, Verónica

    2017-05-01

    In this study, one-step co-precipitation method was conveniently adapted to obtain novel nanomaterials based on Gum Arabic and magnetite. Two synthesis procedures were evaluated: one employing the solid biopolymer in the co-precipitation media; a second using an aqueous solution of the polysaccharide. An exhaustive characterization of both formulations was performed using several specific techniques. The obtained data confirmed the successful incorporation of the gum Arabic on the magnetic core. Values of hydrodynamic diameters, measured by dynamic light scattering, in aqueous dispersions were about 70-80nm, while sizes lower than 20nm were registered by TEM microscopy. Surface charge of gum Arabic coated magnetic nanoparticles was significantly different from the corresponding to raw materials (magnetite and GA). This fact confirmed the formation of hybrid nanosystems with novel and specific properties. The potential utility of these materials was tested regarding to magnetic hyperthermia therapy under radiofrequency fields. Magnetocalorimetric measurements were performed in a wide range of field amplitude and frequency. Specific absorption rate of 218W/gFe was determined at field frequency of 260kHz and amplitude of 52kA/m. These results demonstrate their viability to be applied in tumor ablation treatments. Using the linear response theory and restricting field parameters to the accepted biomedical window, maximum useful value of 74w/gFe is predicted at 417kHz and 12kA/m.

  11. In vitro biocompatibility assessment of functionalized magnetite nanoparticles: biological and cytotoxicological effects.

    PubMed

    Mbeh, D A; França, R; Merhi, Y; Zhang, X F; Veres, T; Sacher, E; Yahia, L

    2012-06-01

    In the biomedical field, nanomaterials have the potential for use in the targeted delivery of drugs in the human body and in the diagnosis and therapy of certain diseases. In the category of targeted delivery, magnetite (Fe(3)O(4)) nanoparticles have received much attention. As with any similar new therapy, when such nanoparticles are functionalized with chemical groups designed to permit the specific attachment of drugs, cytotoxicological testing is necessary before moving to animal models. Here, we consider several variously functionalized magnetite nanoparticles, including those prepared with (1) a monolayer of oleic acid (Fe(3)O(4)@OA), which is subsequently converted to (2) a shell of amine-containing silane (Fe(3)O(4)@NH(2)), (3) a shell of silica (Fe(3)O(4)@SiO(2)), and (4) a shell of amine-containing silane over a shell of silica (Fe(3)O(4)@SiO(2)@NH(2)). These latter three functionalities were evaluated for biocompatibility, cellular morphology, mitochondrial function (MTT assay), lactate dehydrogenase membrane leakage (LDH assay), and proinflammatory potential through enzyme linked immunosorbent assay (ELISA) for interleukin 6 (IL-6). Controlled tests were performed over a period of 72 h, with results showing LDH leakage and abnormal Il-6 secretion at high concentrations (>50 μg/mL). The tests showed that, in addition to the surface characteristics of the nanoparticles, both the nutrient medium and the time of suspension before exposure to cells also contribute to nanoparticle cytotoxicity.

  12. Magnetite nanoparticles for functionalized textile dressing to prevent fungal biofilms development

    NASA Astrophysics Data System (ADS)

    Anghel, Ion; Grumezescu, Alexandru Mihai; Andronescu, Ecaterina; Anghel, Alina Georgiana; Ficai, Anton; Saviuc, Crina; Grumezescu, Valentina; Vasile, Bogdan Stefan; Chifiriuc, Mariana Carmen

    2012-09-01

    The purpose of this work was to investigate the potential of functionalized magnetite nanoparticles to improve the antibiofilm properties of textile dressing, tested in vitro against monospecific Candida albicans biofilms. Functionalized magnetite (Fe3O4/C18), with an average size not exceeding 20 nm, has been synthesized by precipitation of ferric and ferrous salts in aqueous solution of oleic acid (C18) and NaOH. Transmission electron microscopy, X-ray diffraction analysis, and differential thermal analysis coupled with thermo gravimetric analysis were used as characterization methods for the synthesized Fe3O4/C18. Scanning electron microscopy was used to study the architecture of the fungal biofilm developed on the functionalized textile dressing samples and culture-based methods for the quantitative assay of the biofilm-embedded yeast cells. The optimized textile dressing samples proved to be more resistant to C. albicans colonization, as compared to the uncoated ones; these functionalized surfaces-based approaches are very useful in the prevention of wound microbial contamination and subsequent biofilm development on viable tissues or implanted devices.

  13. Magnetite-platinum nanoparticles-modified glassy carbon electrode as electrochemical detector for nitrophenol isomers.

    PubMed

    Gerent, Giles G; Spinelli, Almir

    2017-05-15

    A glassy carbon electrode was modified with magnetite and platinum nanoparticles stabilized with 3-n-propyl-4-picoline silsesquioxane chloride. This chemically-modified electrode is proposed for the first time for the individual or simultaneous electrochemical detection of nitrophenol isomers. Nanoparticles act as catalysts and also increase the surface area. The polymer stabilizes the particles and provides the electrochemical separation of isomers. Under optimized conditions, the reduction peak currents, obtained by differential-pulse voltammetry, of 2-, 3-, and 4-nitrophenol increased linearly with increases in their concentration in the range of 0.1-1.5μmolL(-1). In individual analysis, the detection limits were 33.7nmolL(-1), 45.3nmolL(-1) and 48.2nmolL(-1), respectively. Also, simultaneous analysis was possible for 2-, and 4-nitrophenol. In this case, the separation of the peak potentials was 0.138V and the detection limits were 69.6nmolL(-1) and 58.0nmolL(-1), respectively. These analytical figures of merit evidence the outstanding performance of the modified electrode, which was also successfully applied to the individual determination of isomers in environmental and biological samples. The magnetite and platinum nanoparticles modified glassy carbon electrode was able to detect nitrophenol isomers at the ppm level in rain water and human urine samples.

  14. A simple approach to the synthesis of hollow microspheres with magnetite/silica hybrid walls.

    PubMed

    Liu, Jia; Deng, Yonghui; Liu, Chong; Sun, Zhenkun; Zhao, Dongyuan

    2009-05-01

    In this paper, we report a simple approach for templating synthesis of magnetic hollow composite microspheres with magnetite/silica walls. This approach is based on the co-sedimentation of polymer microspheres and magnetic colloids followed by impregnation with silica oligomer from tetraethyl orthosilicate and the further removal of the polymer microspheres by pyrolysis. The diameter of the hollow microspheres can be adjusted in range of 300 nm-2.0 microm by using polymer microspheres of different sizes and the wall thickness is tunable from 10-50 nm by controlling ratio of magnetite to the polymer microspheres. Magnetic characterizations show that the hollow microspheres have superparamagnetism with magnetization saturation of 10-30 emu/g. HRTEM and N(2) adsorption-desorption isotherms reveal that the hollow microspheres have numerous nanopores in the walls with a broad distribution in the range of 2 to 80 nm, which results in a high BET surface (67.6 m(2)/g) and pores volume (0.14 cm(3)/g).

  15. Anionic magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid for DNA base discrimination

    NASA Astrophysics Data System (ADS)

    Khadsai, Sudarat; Rutnakornpituk, Boonjira; Vilaivan, Tirayut; Nakkuntod, Maliwan; Rutnakornpituk, Metha

    2016-09-01

    Magnetite nanoparticles (MNPs) were surface modified with anionic poly( N-acryloyl glycine) (PNAG) and streptavidin for specific interaction with biotin-conjugated pyrrolidinyl peptide nucleic acid (PNA). Hydrodynamic size ( D h) of PNAG-grafted MNPs varied from 334 to 496 nm depending on the loading ratio of the MNP to NAG in the reaction. UV-visible and fluorescence spectrophotometries were used to confirm the successful immobilization of streptavidin and PNA on the MNPs. About 291 pmol of the PNA/mg MNP was immobilized on the particle surface. The PNA-functionalized MNPs were effectively used as solid supports to differentiate between fully complementary and non-complementary/single-base mismatch DNA using the PNA probe. These novel anionic MNPs can be efficiently applicable for use as a magnetically guidable support for DNA base discrimination.

  16. Microstructure and self-sharpening of the magnetite cap in chiton tooth.

    PubMed

    Wang, C; Li, Q Y; Wang, S N; Qu, S X; Wang, X X

    2014-04-01

    The magnetite cap of chiton tooth (Acanthochiton rubrolineatus) was studied with SEM. Three microstructurally distinct regions were recognized: Region I, close to the anterior surface of the cusp and composed of thick rod microstructure units; Region III, close to the posterior surface and composed of fine fibers; and Region II, sandwiched between Regions I and II and composed of thin sheets. The microstructure units in the three regions constitute a continuous and integrated architecture component. The hardness of Regions I and II was measured to be Hv270 and Hv490, respectively. Based on these microstructure observation and hardness data, the abrasive behavior and microstructural mechanism of self-sharpening of the chiton tooth were discussed in the paper. The self-sharpening was attributed to the combined effect of the hardness and the texture orientation of the microstructure units in Regions I and II.

  17. Geochemistry of magnetite from porphyry Cu and skarn deposits in the southwestern United States

    USGS Publications Warehouse

    Nadoll, Patrick; Mauk, Jeffrey L.; LeVeille, Richard A.; Koenig, Alan E.

    2015-01-01

    A combination of petrographic observations, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and statistical data exploration was used in this study to determine compositional variations in hydrothermal and igneous magnetite from five porphyry Cu–Mo and skarn deposits in the southwestern United States, and igneous magnetite from the unmineralized, granodioritic Inner Zone Batholith, Japan. The most important overall discriminators for the minor and trace element chemistry of magnetite from the investigated porphyry and skarn deposits are Mg, Al, Ti, V, Mn, Co, Zn, and Ga—of these the elements with the highest variance for (I) igneous magnetite are Mg, Al, Ti, V, Mn, Zn, for (II) hydrothermal porphyry magnetite are Mg, Ti, V, Mn, Co, Zn, and for (III) hydrothermal skarn magnetite are Mg, Ti, Mn, Zn, and Ga. Nickel could only be detected at levels above the limit of reporting (LOR) in two igneous magnetites. Equally, Cr could only be detected in one igneous occurrence. Copper, As, Mo, Ag, Au, and Pb have been reported in magnetite by other authors but could not be detected at levels greater than their respective LORs in our samples. Comparison with the chemical signature of igneous magnetite from the barren Inner Zone Batholith, Japan, suggests that V, Mn, Co, and Ga concentrations are relatively depleted in magnetite from the porphyry and skarn deposits. Higher formation conditions in combination with distinct differences between melt and hydrothermal fluid compositions are reflected in Al, Ti, V, and Ga concentrations that are, on average, higher in igneous magnetite than in hydrothermal magnetite (including porphyry and skarn magnetite). Low Ti and V concentrations in combination with high Mn concentrations are characteristic features of magnetite from skarn deposits. High Mg concentrations (<1,000 ppm) are characteristic for magnetite from magnesian skarn and likely reflect extensive fluid/rock interaction. In porphyry deposits

  18. Geochemistry of magnetite from porphyry Cu and skarn deposits in the southwestern United States

    NASA Astrophysics Data System (ADS)

    Nadoll, Patrick; Mauk, Jeffrey L.; Leveille, Richard A.; Koenig, Alan E.

    2015-04-01

    A combination of petrographic observations, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and statistical data exploration was used in this study to determine compositional variations in hydrothermal and igneous magnetite from five porphyry Cu-Mo and skarn deposits in the southwestern United States, and igneous magnetite from the unmineralized, granodioritic Inner Zone Batholith, Japan. The most important overall discriminators for the minor and trace element chemistry of magnetite from the investigated porphyry and skarn deposits are Mg, Al, Ti, V, Mn, Co, Zn, and Ga—of these the elements with the highest variance for (I) igneous magnetite are Mg, Al, Ti, V, Mn, Zn, for (II) hydrothermal porphyry magnetite are Mg, Ti, V, Mn, Co, Zn, and for (III) hydrothermal skarn magnetite are Mg, Ti, Mn, Zn, and Ga. Nickel could only be detected at levels above the limit of reporting (LOR) in two igneous magnetites. Equally, Cr could only be detected in one igneous occurrence. Copper, As, Mo, Ag, Au, and Pb have been reported in magnetite by other authors but could not be detected at levels greater than their respective LORs in our samples. Comparison with the chemical signature of igneous magnetite from the barren Inner Zone Batholith, Japan, suggests that V, Mn, Co, and Ga concentrations are relatively depleted in magnetite from the porphyry and skarn deposits. Higher formation conditions in combination with distinct differences between melt and hydrothermal fluid compositions are reflected in Al, Ti, V, and Ga concentrations that are, on average, higher in igneous magnetite than in hydrothermal magnetite (including porphyry and skarn magnetite). Low Ti and V concentrations in combination with high Mn concentrations are characteristic features of magnetite from skarn deposits. High Mg concentrations (<1,000 ppm) are characteristic for magnetite from magnesian skarn and likely reflect extensive fluid/rock interaction. In porphyry deposits

  19. Growing ZnO crystals on magnetite nanoparticles.

    PubMed

    Turgeman, Rachel; Tirosh, Shay; Gedanken, Aharon

    2004-04-02

    We report herein on the oriented growth of ZnO crystals on magnetite nanoparticles. The ZnO crystals were grown by hydrolyzing a supersaturated aqueous solution of zinc nitrate. The seeds for the growth were magnetite nanoparticles with a diameter of 5.7 nm and a narrow size distribution. Hollowed ZnO hexagons of 0.15 microm width and 0.5 microm length filled with Fe(3)O(4) particles were obtained. HR-TEM (high-resolution transmission electron microscopy) and selected-area EDS (energy-dispersive spectroscopy) show that the nanoparticles are homogenously spread in the ZnO tubes. Zeta potential measurements were employed to understand the relationship between the nanoparticles and the oriented growth of the ZnO crystals. The results show that the surfactants induced the directional growth of the ZnO crystals.

  20. Single crystalline superstructured stable single domain magnetite nanoparticles

    PubMed Central

    Reichel, Victoria; Kovács, András; Kumari, Monika; Bereczk-Tompa, Éva; Schneck, Emanuel; Diehle, Patrick; Pósfai, Mihály; Hirt, Ann M.; Duchamp, Martial; Dunin-Borkowski, Rafal E.; Faivre, Damien

    2017-01-01

    Magnetite nanoparticles exhibit magnetic properties that are size and organization dependent and, for applications that rely on their magnetic state, they usually have to be monodisperse. Forming such particles, however, has remained a challenge. Here, we synthesize 40 nm particles of magnetite in the presence of polyarginine and show that they are composed of 10 nm building blocks, yet diffract like single crystals. We use both bulk magnetic measurements and magnetic induction maps recorded from individual particles using off-axis electron holography to show that each 40 nm particle typically contains a single magnetic domain. The magnetic state is therefore determined primarily by the size of the superstructure and not by the sizes of the constituent sub-units. Our results fundamentally demonstrate the structure – property relationship in a magnetic mesoparticle. PMID:28358051

  1. Magnetite-doped polydimethylsiloxane (PDMS) for phosphopeptide enrichment.

    PubMed

    Sandison, Mairi E; Jensen, K Tveen; Gesellchen, F; Cooper, J M; Pitt, A R

    2014-10-07

    Reversible phosphorylation plays a key role in numerous biological processes. Mass spectrometry-based approaches are commonly used to analyze protein phosphorylation, but such analysis is challenging, largely due to the low phosphorylation stoichiometry. Hence, a number of phosphopeptide enrichment strategies have been developed, including metal oxide affinity chromatography (MOAC). Here, we describe a new material for performing MOAC that employs a magnetite-doped polydimethylsiloxane (PDMS), that is suitable for the creation of microwell array and microfluidic systems to enable low volume, high throughput analysis. Incubation time and sample loading were explored and optimized and demonstrate that the embedded magnetite is able to enrich phosphopeptides. This substrate-based approach is rapid, straightforward and suitable for simultaneously performing multiple, low volume enrichments.

  2. Electrostatic powder spraying process for the fabrication of stable superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Gu, Guotuan; Tian, Yuping; Li, Zhantie; Lu, Dongfang

    2011-03-01

    Nano-sized Al2O3 particles were modified by heptadecafluorodecyl trimethoxysilane and 2,3-epoxy propoxy propyl trimethoxysilicane to make it both hydrophobic and reactive. The reactive nano-particles were mixed with polyester resin containing curing agents and electrostatic sprayed on stainless steel substrates to obtain stable superhydrophobic coatings after curing. The water contact angle (WCA) on the hybrid coating is influenced by the content of Al2O3 particles in the coating. As the Al2O3 concentration in the coating was increased from 0% to 8%, WCA increased from 68° to 165°. Surface topography of the coatings was examined using scanning electron microscopy (SEM). Nano-particles covered on the coating surface formed continuous film with greatly enhanced roughness, which was found to be responsible for the superhydrophobicity. The method is simple and cost effective and can be used for preparing self-cleaning superhydrophobic coating on large areas.

  3. Characterization of magnetite in silico-aluminous fly ash by SEM, TEM, XRD, magnetic susceptibility, and Moessbauer spectroscopy

    SciTech Connect

    Gomes, S.; Francois, M.; Abdelmoula, M.; Refait, P.; Pellissier, C.; Evrard, O.

    1999-11-01

    Spinel magnetite contained in a silico-aluminous fly ash (originating from la Maxe's power plant, near Metz in the east of France) issued from bituminous coal combustion has been studied by scanning and transmission electron microscopy linked with energy dispersive spectroscopy. X-ray diffraction, susceptibility measurements, and Moessbauer spectroscopy. The results show that in this magnetite Mg is strongly substituted for Fe and the chemical formula is closer to MgFe{sub 2}O{sub 4} than Fe{sub 3}O{sub 4}. Magnetite also contains Mn, Ca, and Si elements, but at a lower proportion. The results are compatible with the chemical formula Fe{sub 2.08}Mg{sub 0.75}Mn{sub 0.11}Ca{sub 0.04}Si{sub 0.02}O{sub 4} and crystallochemical formula [Fe{sup 2{minus}}{sub 0.92}Ca{sup 2+}{sub 0.06}Si{sup 4+}{sub 0.02}]{sup tetra}[Fe{sup 3+}Fe{sup 2+}{sub 0.16}Mg{sup 2+}{sub 0.73}Mn{sup 2+}{sub 0.11}]{sup octa}O{sub 4}, showing the cation distribution on octahedral and tetrahedral sites of the spinel structure. The reason Mg element is not incorporated in soluble surface salt and in glass composition of the silico-aluminous fly ashes is now understood.

  4. Surfactant-free miniemulsion polymerization as a simple synthetic route to a successful encapsulation of magnetite nanoparticles.

    PubMed

    Ramos, Jose; Forcada, Jacqueline

    2011-06-07

    Due to the existing interest in new hybrid particles in the colloidal range based on both magnetic and polymeric materials for applications in biotechnological fields, this work is focused on the preparation of magnetic polymer nanoparticles (MPNPs) by a single-step miniemulsion process developed to achieve better control of the morphology of the magnetic nanocomposite particles. MPNPs are prepared by surfactant-free miniemulsion polymerization using styrene (St) as a monomer, hexadecane (HD) as a hydrophobe, and potassium persulfate (KPS) as an initiator in the presence of oleic acid (OA)-modified magnetite nanoparticles. The effect of the type of cross-linker used [divinylbenzene (DVB) and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP)] together with the effect of the amount of an aid stabilizer (dextran) on size, particle size distribution (PSD), and morphology of the hybrid nanoparticles synthesized is analyzed in detail. The mixture of different surface modifiers produces hybrid nanocolloids with various morphologies: from a typical core-shell composed by a magnetite core surrounded by a polymer shell to a homogeneously distributed morphology where the magnetite is uniformly distributed throughout the entire nanocomposite.

  5. Field Evidence for Magnetite Formation by a Methanogenic Microbial Community

    NASA Astrophysics Data System (ADS)

    Rossbach, S.; Beaver, C. L.; Williams, A.; Atekwana, E. A.; Slater, L. D.; Ntarlagiannis, D.; Lund, A.

    2015-12-01

    The aged, subsurface petroleum spill in Bemidji, Minnesota, has been surveyed with magnetic susceptibility (MS) measurements. High MS values were found in the free-product phase around the fluctuating water table. Although we had hypothesized that high MS values are related to the occurrence of the mineral magnetite resulting from the activity of iron-reducing bacteria, our microbial analysis pointed to the presence of a methanogenic microbial community at the locations and depths of the highest MS values. Here, we report on a more detailed microbial analysis based on high-throughput sequencing of the 16S rRNA gene of sediment samples from four consecutive years. In addition, we provide geochemical data (FeII/FeIII concentrations) to refine our conceptual model of methanogenic hydrocarbon degradation at aged petroleum spills and demonstrate that the microbial induced changes of sediment properties can be monitored with MS. The methanogenic microbial community at the Bemidji site consisted mainly of the syntrophic, hydrocarbon-degrading Smithella and the hydrogenotrophic, methane-generating Methanoregula. There is growing evidence in the literature that not only Bacteria, but also some methanogenic Archaea are able to reduce iron. In fact, a recent study reported that the methanogen Methanosarcina thermophila produced magnetite during the reduction of ferrihydrite in a laboratory experiment when hydrogen was present. Therefore, our finding of high MS values and the presence of magnetite in the methanogenic zone of an aged, subsurface petroleum spill could very well be the first field evidence for magnetite formation during methanogenic hydrocarbon degradation.

  6. Hematite Versus Magnetite as the Signature for Planetary Magnetic Anomalies?

    NASA Technical Reports Server (NTRS)

    Kletetshka, Gunther; Taylor, Patrick T.; Wasilewski, Peter J.

    1999-01-01

    Crustal magnetic anomalies are the result of adjacent geologic units having contrasting magnetization. This magnetization arises from induction and/or remanence. In a planetary context we now know that Mars has significant crustal magnetic anomalies due to remanent magnetization, while the Earth has some anomalies where remanence can be shown to be important. This picture, however, is less clear because of the nature and the magnitude of the geomagnetic field which is responsible for superimposed induced magnetization. Induced magnetization assumes a magnetite source, because of its much greater magnetic susceptibility when compared with other magnetic minerals. We investigated the TRM (thermoremanent magnetization) acquisition of hematite, in weak magnetic fields up to 1 mT, to determine if the remanent and induced magnetization of hematite could compete with magnetite. TRM acquisition curves of magnetite and hematite show that multi-domain hematite reaches TRM saturation (0.3 - 0.4 A sq m/kg) in fields as low as 100 microT. However, multi-domain magnetite reaches only a fe