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Sample records for 4n nanometric oxides

  1. Development of graphene-nanometre-sized cerium oxide-incorporated aluminium and its electrochemical evaluation

    NASA Astrophysics Data System (ADS)

    Ashraf, P. Muhamed; Thomas, Saly N.; Edwin, Leela

    2016-02-01

    Graphene-nanometre-sized cerium oxide-incorporated aluminium was prepared and its electrochemical and surface morphological characteristics were studied. The atomic force micrographs and scanning electron micrographs evaluation highlighted that the graphene and nanometre-sized cerium oxide in aluminium had decreased the surface roughness and improved the surface morphological characteristics. The graphene: nanometre-sized cerium oxide (ratios 1:2 or 2:1) with lesser amounts of particle in the matrix showed excellent corrosion resistance in the marine environment as evidenced by linear polarization, electrochemical impedance and weight loss studies. Introduction of graphene in the aluminium matrix showed a barrier separation between the outermost layer and inner layer, increased roughness and increased corrosion. The material is found to be a potential candidate for use in marine environment.

  2. Observation of Nanometric Silicon Oxide Bifilms in a Water-Atomized Hypereutectic Cast Iron Powder

    NASA Astrophysics Data System (ADS)

    Boisvert, Mathieu; Christopherson, Denis; L'Espérance, Gilles

    2016-10-01

    This study investigated the reasons for the irregular structure of primary graphite nodules that were formed in a hypereutectic cast iron powder during water atomization. The graphite nodules contain a significant amount of micron-sized pores and multiple nanometric voids that formed from silicon oxide bifilms. The bifilms theory is often used to explain the mechanisms responsible for the presence of pores in castings. However, even if many results presented in the literature tend to corroborate the existence of bifilms, to this date, only indirect evidences of their existence were presented. The observations presented in this paper are the first to show the double-sided nature of these defects. These observations support the bifilms theory and give an explanation for the presence of porosities in castings. The bifilms were used as substrate for graphite growth during solidification. The irregular structure of the graphite nodules is a consequence of the rather random structure of the bifilms that were introduced in the melt as a result of turbulences on the surface of the melt during pouring. The confirmation of the existence of bifilms can contribute to the understanding of the mechanical properties of various metallic parts.

  3. Observation of Nanometric Silicon Oxide Bifilms in a Water-Atomized Hypereutectic Cast Iron Powder

    NASA Astrophysics Data System (ADS)

    Boisvert, Mathieu; Christopherson, Denis; L'Espérance, Gilles

    2016-06-01

    This study investigated the reasons for the irregular structure of primary graphite nodules that were formed in a hypereutectic cast iron powder during water atomization. The graphite nodules contain a significant amount of micron-sized pores and multiple nanometric voids that formed from silicon oxide bifilms. The bifilms theory is often used to explain the mechanisms responsible for the presence of pores in castings. However, even if many results presented in the literature tend to corroborate the existence of bifilms, to this date, only indirect evidences of their existence were presented. The observations presented in this paper are the first to show the double-sided nature of these defects. These observations support the bifilms theory and give an explanation for the presence of porosities in castings. The bifilms were used as substrate for graphite growth during solidification. The irregular structure of the graphite nodules is a consequence of the rather random structure of the bifilms that were introduced in the melt as a result of turbulences on the surface of the melt during pouring. The confirmation of the existence of bifilms can contribute to the understanding of the mechanical properties of various metallic parts.

  4. Oxygen stoichiometry control of nanometric oxide compounds: The case of titanium ferrites

    SciTech Connect

    Millot, N.

    2011-10-15

    Three techniques have been coupled with an original device, based on H{sub 2}/H{sub 2}O equilibrium, controlling oxygen partial pressure: XRD, TGA and DC conductivity in order to characterize very reactive compounds such as nanometric powders. From XRD, both the structure and the oxygen stoichiometry (thanks to their lattice parameter) were investigated in situ. From TGA, it was the oxygen stoichiometry (thanks to mass gain or loss) which was determined. From DC conductivity, it was both the structure and the oxygen stoichiometry (thanks to the activation energy) which were obtained. The advantages were to determine very rapidly and with a small amount of powder the equilibrium conditions (T, pO{sub 2}) necessary to obtain the desired phase and stoichiometry. These methods have been evaluated for nanometric titanium ferrites. Two phenomena have been observed during the reducing process: the precipitation of a rhombohedral phase and a significant grain growth linked together. - Graphical abstract: XRD patterns of Fe{sub 3(1-{delta})}O{sub 4} nanometric powders obtained in situ during a reducing treatment. The stoichiometric compound was obtained by a thermal annealing at 460 deg. C under pO{sub 2}=3x10{sup -26} Pa ({Phi}{sub DRX}=100 nm). In inset, data of the experimental lattice parameter compared to the theoretical one. {alpha} represents the rhomboedrical phase which precipitates during this thermal treatment, then disappeared. Highlights: > The control of the deviation from oxygen stoichiometry is rarely consider in literature. > At the nanometric scale, it is necessary to develop synthesis routes under appropriate atmosphere. > These synthesis must be coupled with in situ characterization tools. > It opens the door to fast and precise studies concerning the evolution of nanometric materials.

  5. Magnetotactic bacteria form magnetite from a phosphate-rich ferric hydroxide via nanometric ferric (oxyhydr)oxide intermediates

    PubMed Central

    Baumgartner, Jens; Morin, Guillaume; Menguy, Nicolas; Perez Gonzalez, Teresa; Widdrat, Marc; Cosmidis, Julie; Faivre, Damien

    2013-01-01

    The iron oxide mineral magnetite (Fe3O4) is produced by various organisms to exploit magnetic and mechanical properties. Magnetotactic bacteria have become one of the best model organisms for studying magnetite biomineralization, as their genomes are sequenced and tools are available for their genetic manipulation. However, the chemical route by which magnetite is formed intracellularly within the so-called magnetosomes has remained a matter of debate. Here we used X-ray absorption spectroscopy at cryogenic temperatures and transmission electron microscopic imaging techniques to chemically characterize and spatially resolve the mechanism of biomineralization in those microorganisms. We show that magnetite forms through phase transformation from a highly disordered phosphate-rich ferric hydroxide phase, consistent with prokaryotic ferritins, via transient nanometric ferric (oxyhydr)oxide intermediates within the magnetosome organelle. This pathway remarkably resembles recent results on synthetic magnetite formation and bears a high similarity to suggested mineralization mechanisms in higher organisms. PMID:23980143

  6. Magnetotactic bacteria form magnetite from a phosphate-rich ferric hydroxide via nanometric ferric (oxyhydr)oxide intermediates.

    PubMed

    Baumgartner, Jens; Morin, Guillaume; Menguy, Nicolas; Perez Gonzalez, Teresa; Widdrat, Marc; Cosmidis, Julie; Faivre, Damien

    2013-09-10

    The iron oxide mineral magnetite (Fe3O4) is produced by various organisms to exploit magnetic and mechanical properties. Magnetotactic bacteria have become one of the best model organisms for studying magnetite biomineralization, as their genomes are sequenced and tools are available for their genetic manipulation. However, the chemical route by which magnetite is formed intracellularly within the so-called magnetosomes has remained a matter of debate. Here we used X-ray absorption spectroscopy at cryogenic temperatures and transmission electron microscopic imaging techniques to chemically characterize and spatially resolve the mechanism of biomineralization in those microorganisms. We show that magnetite forms through phase transformation from a highly disordered phosphate-rich ferric hydroxide phase, consistent with prokaryotic ferritins, via transient nanometric ferric (oxyhydr)oxide intermediates within the magnetosome organelle. This pathway remarkably resembles recent results on synthetic magnetite formation and bears a high similarity to suggested mineralization mechanisms in higher organisms.

  7. Magnetotactic bacteria form magnetite from a phosphate-rich ferric hydroxide via nanometric ferric (oxyhydr)oxide intermediates.

    PubMed

    Baumgartner, Jens; Morin, Guillaume; Menguy, Nicolas; Perez Gonzalez, Teresa; Widdrat, Marc; Cosmidis, Julie; Faivre, Damien

    2013-09-10

    The iron oxide mineral magnetite (Fe3O4) is produced by various organisms to exploit magnetic and mechanical properties. Magnetotactic bacteria have become one of the best model organisms for studying magnetite biomineralization, as their genomes are sequenced and tools are available for their genetic manipulation. However, the chemical route by which magnetite is formed intracellularly within the so-called magnetosomes has remained a matter of debate. Here we used X-ray absorption spectroscopy at cryogenic temperatures and transmission electron microscopic imaging techniques to chemically characterize and spatially resolve the mechanism of biomineralization in those microorganisms. We show that magnetite forms through phase transformation from a highly disordered phosphate-rich ferric hydroxide phase, consistent with prokaryotic ferritins, via transient nanometric ferric (oxyhydr)oxide intermediates within the magnetosome organelle. This pathway remarkably resembles recent results on synthetic magnetite formation and bears a high similarity to suggested mineralization mechanisms in higher organisms. PMID:23980143

  8. 4-N,N-Dimethylaminopyridine promoted selective oxidation of methyl aromatics with molecular oxygen.

    PubMed

    Zhang, Zhan; Gao, Jin; Wang, Feng; Xu, Jie

    2012-03-30

    4-N,N-Dimethylaminopyridine (DMAP) as catalyst in combination with benzyl bromide was developed for the selective oxidation of methyl aromatics. DMAP exhibited higher catalytic activity than other pyridine analogues, such as 4-carboxypyridine, 4-cyanopyridine and pyridine. The sp3 hybrid carbon-hydrogen (C-H) bonds of different methyl aromatics were successfully oxygenated with molecular oxygen. The real catalyst is due to the formation of a pyridine onium salt from the bromide and DMAP. The onium salt was well characterized by NMR and the reaction mechanism was discussed.

  9. Biodistribution study of nanometric hybrid gadolinium oxide particles as a multimodal SPECT/MR/optical imaging and theragnostic agent.

    PubMed

    Kryza, David; Taleb, Jacqueline; Janier, Marc; Marmuse, Laurence; Miladi, Imen; Bonazza, Pauline; Louis, Cédric; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier; Billotey, Claire

    2011-06-15

    Nanometric hybrid gadolinium oxide particles (Gado-6Si-NP) for diagnostic and therapeutic applications (mean diameter 3-4 nm) were obtained by encapsulating Gd(2)O(3) cores within a polysiloxane shell, which carries organic fluorophore (Cy 5) and is derivatized by a hydrophilic carboxylic layer. As residency time in the living body and methods of waste elimination are crucial to defining a good nanoparticle candidate and moving forward with steps for validation, this study was aimed at evaluating the biodistribution of these multimodal Gado-6Si-NP in rodents. Gado-6Si-NP were imaged following intravenous injection in control Wistar rats and mice using MRI (7 T), optical fluorescent imaging, and SPECT. A clear correlation was observed among MRI, optical imaging, and SPECT regarding the renal elimination. Quantitative biodistribution using gamma-counting of each sampled organ confirmed that these nanoparticles circulated freely in the blood pool and were rapidly cleared by renal excretion without accumulation in liver and RES uptake. These results demonstrate that Gado-6Si-NP display optimal biodistribution properties, enabling them to be developed as multimodal agents for in vivo imaging and theragnostics, especially in oncological applications.

  10. Bacterial nanometric amorphous Fe-based oxide: a potential lithium-ion battery anode material.

    PubMed

    Hashimoto, Hideki; Kobayashi, Genki; Sakuma, Ryo; Fujii, Tatsuo; Hayashi, Naoaki; Suzuki, Tomoko; Kanno, Ryoji; Takano, Mikio; Takada, Jun

    2014-04-23

    Amorphous Fe(3+)-based oxide nanoparticles produced by Leptothrix ochracea, aquatic bacteria living worldwide, show a potential as an Fe(3+)/Fe(0) conversion anode material for lithium-ion batteries. The presence of minor components, Si and P, in the original nanoparticles leads to a specific electrode architecture with Fe-based electrochemical centers embedded in a Si, P-based amorphous matrix.

  11. AQ4N: an alkylaminoanthraquinone N-oxide showing bioreductive potential and positive interaction with radiation in vivo.

    PubMed Central

    McKeown, S. R.; Hejmadi, M. V.; McIntyre, I. A.; McAleer, J. J.; Patterson, L. H.

    1995-01-01

    AQ4N (1,4-bis([2-(dimethylamino-N-oxide)ethyl]amino)5,8-dihydroxy- anthracene-9,10-dione) is a novel alkylaminoanthraquinone N-oxide which, on reduction, forms a stable DNA affinic cytotoxic compound AQ4. The in vivo anti-tumour efficacy of AQ4N was investigated in B6D2F1 mice bearing the T50/80 mammary carcinoma. The effect of the drug was evaluated in combination with hypobaric hypoxia and with radiation (single and multiple fractions). Systemic toxicity was assessed by weight loss post treatment. This was low for AQ4N and was less than that obtained with the bioreductive drugs, RSU 1069 (1-[3-aziridinyl-2-hydroxypropyl]-2-nitroimidazole) and SR 4233 (Tirapazamine, 3-amino-1,2,4-benzotriazine-1,4-dioxide). The anti-tumour effect of AQ4N was potentiated in vivo by combination with hypobaric hypoxia with a dose enhancement ratio of 5.1. This is consistent with the proposal that AQ4N was reduced in vivo to AQ4, resulting in enhanced anti-tumour toxicity. When AQ4N (200 mg kg-1) was combined with single dose radiation (12 Gy) the drug was shown to have an additive interaction with radiation. This was obtained even if the drug was administered from 4 days before to 6 h after radiation treatment. Equivalent anti-tumour activity was also shown when both AQ4N (200 mg kg-1) and radiation (5 x 3 Gy) were administered in fractionated schedules. In conclusion, AQ4N shows significant potential as a bioreductive drug for combination with fractionated radiotherapy. PMID:7599069

  12. Chemical synthesis, characterisation, and biocompatibility of nanometre scale porous anodic aluminium oxide membranes for use as a cell culture substrate for the vero cell line: a preliminary study.

    PubMed

    Poinern, Gérrard Eddy Jai; Le, Xuan Thi; O'Dea, Mark; Becker, Thomas; Fawcett, Derek

    2014-01-01

    In this preliminary study we investigate for the first time the biomedical potential of using porous anodic aluminium oxide (AAO) membranes as a cell substrate for culturing the Cercopithecus aethiops (African green monkey) Kidney (Vero) epithelial cell line. One advantage of using the inorganic AAO membrane is the presence of nanometre scale pore channels that allow the exchange of molecules and nutrients across the membrane. The size of the pore channels can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The cellular interaction and response of the Vero cell line with an in-house synthesised AAO membrane, a commercially available membrane, and a glass control were assessed by investigating cell adhesion, morphology, and proliferation over a 72 h period. The number of viable cells proliferating over the respective membrane surfaces revealed that the locally produced in-house AAO membrane had cells numbers similar to the glass control. The study revealed evidence of focal adhesion sites over the surface of the nanoporous membranes and the penetration of cellular extensions into the pore structure as well. The outcome of the study has revealed that nanometre scale porous AAO membranes have the potential to become practical cell culture scaffold substrates with the capability to enhance adhesion and proliferation of Vero cells. PMID:24579077

  13. Interfaces: nanometric dielectrics

    NASA Astrophysics Data System (ADS)

    Lewis, T. J.

    2005-01-01

    The incorporation of nanometric size particles in a matrix to form dielectric composites shows promise of materials (nanodielectrics) with new and improved properties. It is argued that the properties of the interfaces between the particles and the matrix, which will themselves be of nanometric dimensions, will have an increasingly dominant role in determining dielectric performance as the particle size decreases. The forces that determine the electrical and dielectric properties of interfaces are considered, with emphasis on the way in which they might influence composite behaviour. A number of examples are given in which interfaces at the nanometric level exercise both passive and active control over dielectric, optical and conductive properties. Electromechanical properties are also considered, and it is shown that interfaces have important electrostrictive and piezoelectric characteristics. It is demonstrated that the process of poling, namely subjecting macroscopic composite materials to electrical stress and raised temperatures to create piezoelectric materials, can be explained in terms of optimizing the collective response of the nanometric interfaces involved. If the electrical and electromechanical features are coupled to the long-established electrochemical properties, interfaces represent highly versatile active elements with considerable potential in nanotechnology.

  14. Adsorption of 4-n-Nonylphenol and Bisphenol-A on Magnetic Reduced Graphene Oxides: A Combined Experimental and Theoretical Studies.

    PubMed

    Jin, Zhongxiu; Wang, Xiangxue; Sun, Yubing; Ai, Yuejie; Wang, Xiangke

    2015-08-01

    Adsorption of 4-n-nonylphenol (4-n-NP) and bisphenol A (BPA) on magnetic reduced graphene oxides (rGOs) as a function of contact time, pH, ionic strength and humic acid were investigated by batch techniques. Adsorption of 4-n-NP and BPA were independent of pH at 3.0- 8.0, whereas the slightly decreased adsorption was observed at pH 8.0-11.0. Adsorption kinetics and isotherms of 4-n-NP and BPA on magnetic rGOs can be satisfactorily fitted by pseudo-second-order kinetic and Freundlich model, respectively. The maximum adsorption capacities of magnetic rGOs at pH 6.5 and 293 K were 63.96 and 48.74 mg/g for 4-n-NP and BPA, respectively, which were significantly higher than that of activated carbon. Based on theoretical calculations, the higher adsorption energy of rGOs + 4-n-NP was mainly due to π-π stacking and flexible long alkyl chain of 4-n-NP, whereas adsorption of BPA on rGOs was energetically favored by a lying-down configuration due to π-π stacking and dispersion forces, which was further demonstrated by FTIR analysis. These findings indicate that magnetic rGOs is a promising adsorbent for the efficient elimination of 4-n-NP/BPA from aqueous solutions due to its excellent adsorption performance and simple magnetic separation, which are of great significance for the remediation of endocrine-disrupting chemicals in environmental cleanup. PMID:26161689

  15. Lower Saccharide Nanometric Materials and Methods

    SciTech Connect

    Schilling, Christopher H.; Tomasik, Piotr; Sikora, Marek

    2004-07-13

    A ceramic composition having at least one nanometric ceramic powder, at least one lower saccharide, and water. The composition is useful in many industrial applications, including preparation of stronger and substantially defect free green and sintered ceramic bodies.

  16. Ultrasonic cavitation for obtainment of nanometric sized particles

    NASA Astrophysics Data System (ADS)

    Santos, A.; Guzmán, R.; Espinosa, J.; Estrada, J.

    2016-02-01

    This project aims to determine the possibility of obtaining nanometric size particles of aluminium oxide (Al2O3) and titanium dioxide (TiO2) from commercial micron-sized powders, through the physical principle of ultrasonic cavitation, in order to be used as supply material in coatings made through a process of thermal spray by flame. The tests are performed on a Hielscher UIP 1000hd Ultrasonics equipment, in a 20 micron wave amplitude and in times of 6, 8, 12, 18 and 24 hours. The determination of the particle size is done through image processing using ImageJ software, obtained by the technique of scanning electron microscopy (SEM); while the elemental composition of the processed samples is analyzed through the technique of energy dispersing spectroscopy (EDS). The results show that Al2O3 and TiO2 have a reduction behaviour of the particles size after being subjected to ultrasonic cavitation, however is only reached the nanometric size in the TiO2 samples.

  17. Nanometric crystal defects in transmission electron microscopy.

    PubMed

    Schäublin, Robin

    2006-05-01

    Transmission electron microscopy (TEM) is revisited in order to define methods for the identification of nanometric defects. Nanometric crystal defects play an important role as they influence, generally in a detrimental way, physical properties. For instance, radiation-induced damage in metals strongly degrades mechanical properties, rendering the material stronger but brittle. The difficulty in using TEM to identify the nature and size of such defects resides in their small size. TEM image simulations are deployed to explore limits and possible ways to improve on spatial resolution and contrast. The contrast of dislocation loops, cavities, and a stacking fault tetrahedra (SFT) are simulated in weak beam, interfering reflections (HRTEM), and scanned condensed electron probe (STEM) mode. Results indicate that STEM is a possible way to image small defects. In addition, a new objective aperture is proposed to improve resolution in diffraction contrast. It is investigated by simulations of the weak beam imaging of SFT and successfully applied in experimental observations.

  18. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    SciTech Connect

    Li, Chuanping

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  19. Elastic vibrations of spheroidal nanometric particles

    NASA Astrophysics Data System (ADS)

    Hernández-Rosas, Juan; Picquart, Michel; Haro-Poniatowski, Emmanuel; Kanehisa, Makoto; Jouanne, Michel; François Morhange, Jean

    2003-11-01

    Particles of nanometric size show low-frequency vibrational modes that can be observed by Raman spectroscopy. These modes involve the collective motion of large numbers of atoms and it is possible to calculate their frequency using elasticity theory. In this work a simple model for oblate-shaped nanoparticles is developed and compared with experimental results obtained in bismuth nanoparticles. It is found that the agreement between theory and experiment is improved in comparison to the spherical model usually employed. However for the smallest particles the elastic model is no longer valid and lattice discreteness has to be considered.

  20. Fabrication of solid-state nanopores with single-nanometre precision.

    PubMed

    Storm, A J; Chen, J H; Ling, X S; Zandbergen, H W; Dekker, C

    2003-08-01

    Single nanometre-sized pores (nanopores) embedded in an insulating membrane are an exciting new class of nanosensors for rapid electrical detection and characterization of biomolecules. Notable examples include alpha-hemolysin protein nanopores in lipid membranes and solid-state nanopores in Si3N4. Here we report a new technique for fabricating silicon oxide nanopores with single-nanometre precision and direct visual feedback, using state-of-the-art silicon technology and transmission electron microscopy. First, a pore of 20 nm is opened in a silicon membrane by using electron-beam lithography and anisotropic etching. After thermal oxidation, the pore can be reduced to a single-nanometre when it is exposed to a high-energy electron beam. This fluidizes the silicon oxide leading to a shrinking of the small hole due to surface tension. When the electron beam is switched off, the material quenches and retains its shape. This technique dramatically increases the level of control in the fabrication of a wide range of nanodevices.

  1. The biological response to nanometre-sized polymer particles.

    PubMed

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L; Ingham, Eileen; Fisher, John; Tipper, Joanne L

    2015-09-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1-1.0μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20nm, 60nm, 200nm and 1.0μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100μm(3) particles per cell after 12 and 24h. The micrometre-size UHMWPE wear particles (0.1-1.0μm) and 60nm, 200nm and 1.0μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. PMID:26004221

  2. The biological response to nanometre-sized polymer particles

    PubMed Central

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L.; Ingham, Eileen; Fisher, John; Tipper, Joanne L.

    2015-01-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1–1.0 μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20 nm, 60 nm, 200 nm and 1.0 μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20 nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100 μm3 particles per cell after 12 and 24 h. The micrometre-size UHMWPE wear particles (0.1–1.0 μm) and 60 nm, 200 nm and 1.0 μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50 nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. PMID:26004221

  3. Deep-subwavelength Nanometric Image Reconstruction using Fourier Domain Optical Normalization

    PubMed Central

    Qin, Jing; Silver, Richard M.; Barnes, Bryan M.; Zhou, Hui; Dixson, Ronald G.; Henn, Mark-Alexander

    2016-01-01

    Quantitative optical measurements of deep sub-wavelength, three-dimensional, nanometric structures with sensitivity to sub-nanometer details address an ubiquitous measurement challenge. A Fourier domain normalization approach is used in the Fourier optical imaging code to simulate the full three-dimensional scattered light field of nominally 15 nm sized structures, accurately replicating the light field as a function of the focus position. Using the full three-dimensional light field, nanometer scale details such as a 2 nm thin conformal oxide and nanometer topography are rigorously fitted for features less than 1/30th of the wavelength in size. The densely packed structures are positioned nearly an order of magnitude closer than the conventional Rayleigh resolution limit and can be measured with sub-nanometer parametric uncertainties. This approach enables a practical measurement sensitivity to size variations of only a few atoms in size using a high throughput optical configuration with broad application in measuring nanometric structures and nanoelectronic devices. PMID:26925297

  4. Design and fabrication of transmission quarter phase retarder at wavelength 1064 nm, using optical nanometric thin films

    NASA Astrophysics Data System (ADS)

    Moradi, Zahra; Jahanshah, Fariborz; Fallah, Hamid Reza; Haji Mahmoodzade, Morteza; Sahraee, Masoume; Zabolian, Hosein

    2016-08-01

    We designed and fabricated the transmission quarter-wave plate phase retarder at 1064 nm using optical nanometric thin films of silicon oxide and titanium oxide. Final design consists of 32 layers. Transmissions of polarizations are equal and ≥99 % and their phase difference is 90°. System consists of two 16 layers systems that coated with the same condition on BK7 glass substrates then attached together with optical glue. Electron beam evaporation method was used for depositing materials. Photo spectrometer was used for measuring transmission spectrum of system. Transmission of polarizations was ≥95 % and equal. A polarimeter was used for testing systems. Polarization of beam was circular.

  5. Study on nanometric cutting of germanium by molecular dynamics simulation

    PubMed Central

    2013-01-01

    Three-dimensional molecular dynamics simulations are conducted to study the nanometric cutting of germanium. The phenomena of extrusion, ploughing, and stagnation region are observed from the material flow. The uncut thickness which is defined as the depth from bottom of the tool to the stagnation region is in proportion to the undeformed chip thickness on the scale of our simulation and is almost independent of the machined crystal plane. The cutting resistance on (111) face is greater than that on (010) face due to anisotropy of germanium. During nanometric cutting, both phase transformation from diamond cubic structure to β-Sn phase and direct amorphization of germanium occur. The machined surface presents amorphous structure. PMID:23289482

  6. Molecular dynamics simulations of nanometric cutting mechanisms of amorphous alloy

    NASA Astrophysics Data System (ADS)

    Zhu, Peng-Zhe; Qiu, Chen; Fang, Feng-Zhou; Yuan, Dan-Dan; Shen, Xue-Cen

    2014-10-01

    Molecular dynamics simulations are employed to study the nanometric cutting process of Cu50Zr50 amorphous alloy. The effects of cutting depth, cutting speed and tool edge radius on the cutting force, workpiece pile-up and temperature of the cutting region are studied to investigate the mechanisms of the material removal and surface formation in the nanometric cutting process. It is found that the material removal of amorphous alloy workpiece is mainly based on extrusion at the nanoscale instead of shearing at the macroscale. The plastic deformation of amorphous alloy is mainly due to the formation of shear transformation zones during the nanometric cutting process. The results also suggest that bigger cutting depth and cutting speed will lead to larger tangential force and normal force. However, the tool edge radius has a negligible effect on the tangential force although the normal force increases with the increase of tool edge radius. The workpiece pile-up increases with an increase of the cutting depth, but decreases with an increase of the edge radius of the tool. The workpiece pile-up is not significantly affected by the cutting speed. It is also found that larger cutting depth and cutting speed will result in higher temperature in the cutting region of workpiece and the average Newtonian layer temperature of the tool. Tool edge radius has no significant effect on the temperature distribution of the workpiece and the average Newtonian layer temperature of the tool.

  7. Technical Note: Nanometric organic photovoltaic thin film detectors for dose monitoring in diagnostic x-ray imaging

    SciTech Connect

    Elshahat, Bassem; Gill, Hardeep Singh; Kumar, Jayant; Filipyev, Ilya; Zygmanski, Piotr; Shrestha, Suman; Karellas, Andrew; Hesser, Jürgen; Sajo, Erno

    2015-07-15

    Purpose: To fabricate organic photovoltaic (OPV) cells with nanometric active layers sensitive to ionizing radiation and measure their dosimetric characteristics in clinical x-ray beams in the diagnostic tube potential range of 60–150 kVp. Methods: Experiments were designed to optimize the detector’s x-ray response and find the best parameter combination by changing the active layer thickness and the area of the electrode. The OPV cell consisted of poly (3-hexylthiophene-2,5-diyl): [6,6]-phenyl C{sub 61} butyric acid methyl ester photoactive donor and acceptor semiconducting organic materials sandwiched between an aluminum electrode as an anode and an indium tin oxide electrode as a cathode. The authors measured the radiation-induced electric current at zero bias voltage in all fabricated OPV cells. Results: The net OPV current as a function of beam potential (kVp) was proportional to kVp{sup −0.5} when normalized to x-ray tube output, which varies with kVp. Of the tested configurations, the best combination of parameters was 270 nm active layer thicknesses with 0.7 cm{sup 2} electrode area, which provided the highest signal per electrode area. For this cell, the measured current ranged from approximately 0.7 to 2.4 nA/cm{sup 2} for 60–150 kVp, corresponding to about 0.09 nA–0.06 nA/mGy air kerma, respectively. When compared to commercial amorphous silicon thin film photovoltaic cells irradiated under the same conditions, this represents 2.5 times greater sensitivity. An additional 40% signal enhancement was observed when a 1 mm layer of plastic scintillator was attached to the cells’ beam-facing side. Conclusions: Since both OPVs can be produced as flexible devices and they do not require external bias voltage, they open the possibility for use as thin film in vivo detectors for dose monitoring in diagnostic x-ray imaging.

  8. Failure of semiclassical models to describe resistivity of nanometric, polycrystalline tungsten films

    SciTech Connect

    Choi, Dooho; Liu, Xuan; Schelling, Patrick K.; Coffey, Kevin R.; Barmak, Katayun

    2014-03-14

    The impact of electron scattering at surfaces and grain boundaries in nanometric polycrystalline tungsten (W) films was studied. A series of polycrystalline W films ranging in thickness from 10 to 310 nm and lateral grain size from 74 to 133 nm were prepared on thermally oxidized Si. The Fuchs-Sondheimer surface-scattering model and Mayadas-Shatzkes grain-boundary scattering model were employed for quantitative analyses. Predictions from the theoretical models were found to deviate systematically from the experimental data. Possible reasons for the failure of the theoretical models to describe the experimental data are explored. Finally, a discussion of the crucial features lacking from existing models is presented, along with possible avenues for improving the models to result in better agreement with experimental data.

  9. Nanometric molecular separation measurements by single molecule photobleaching.

    PubMed

    Webb, Stephen E D; Hirsch, Michael; Needham, Sarah R; Coles, Benjamin C; Scherer, Kathrin M; Roberts, Selene K; Zanetti-Domingues, Laura C; Tynan, Christopher J; Martin-Fernandez, Marisa L; Rolfe, Daniel J

    2015-10-15

    Although considerable progress has been made in imaging distances in cells below the diffraction limit using FRET and super-resolution microscopy, methods for determining the separation of macromolecules in the 10-50 nm range have been elusive. We have developed fluorophore localisation imaging with photobleaching (FLImP), based on the quantised bleaching of individual protein-bound dye molecules, to quantitate the molecular separations in oligomers and nanoscale clusters. We demonstrate the benefits of using our method in studying the nanometric organisation of the epidermal growth factor receptor in cells.

  10. Sub-100-nanometre resolution in total internal reflection fluorescence microscopy.

    PubMed

    Beck, M; Aschwanden, M; Stemmer, A

    2008-10-01

    Combining total internal reflection fluorescence microscopy with structured illumination allows optical wide-field imaging with sub-100-nanometre resolution. We present a novel objective-launch set-up for standing wave illumination that takes advantage of a tunable transmission diffraction grating and transparent phase shifters actuated by electro-active polymers to control the excitation pattern in three dimensions. Image acquisition is completed in less than 1 s. To reconstruct the extended image spectrum, we apply a new apodization function that results in a lateral resolution of 89 nm for green emission wavelength.

  11. [Mechanism of NH(4+)-N removal in drinking water biofilter].

    PubMed

    Liu, Bing; Fan, Hui; Yu, Guo-Zhong; Yu, Xin; Zhao, Cheng-Mei; Li, Qing-Fei; Zhang, Shu-Ting; Wei, Bo

    2012-07-01

    In order to explore the mechanism of NH(4+)-N removal in drinking water biofilter, water quality parameters, such as NH(4+)-N, NO(2-)-N, NO(3-)-N, total phosphorus, permanganate index, nitrogen gas, temperature and dissolved oxygen etc, were determined in the inflow and outflow of biofilter. Samples of granular activated carbon (GAC) at different height (0, 10, 20, 40, 60 cm) of the biofiter media were collected and analyzed for the bacterial community with molecular biology techniques. The bacterial diversity in the activated carbon biofilm sample was studied based on the phylogenetic analysis of sequences. The results showed that there were three stages according to the NH(4+)-N concentration in the influent. The "nitrogen loss" phenomenon (total inorganic nitrogen in the effluent was less than that in the influent) occurred at the first, second and third stages and the amount of nitrogen loss were 0.94, 0.32 and 0.15 mg x L(-1), respectively. The amount of nitrogen loss had a good positive correlation with the NH(4+)-N concentration in the influent, but not a linear relationship with the concentration of the permanganate index in the influent. The average concentrations of N2 increased gradually with the height of media in the biofilter, with values of 14.04 and 14.67 mg x L(-1) in the influent and the effluent, respectively. Based on the sequencing results, the ammonia-oxidizing bacteria (AOB) in the activated carbon biofilm were classified into three common genera: Nitrosococcus, Nitrosomonas and Nitrosospira. When the NH(4+)-N concentration in the influent was relatively high, the "nitrogen loss" phenomenon in biofilter was caused by the AOB.

  12. Nanometric Gouge in High-Speed Shearing Experiments: Superplasticity?

    NASA Astrophysics Data System (ADS)

    Green, H. W.; Lockner, D. A.; Bozhilov, K. N.; Maddon, A.; Beeler, N. M.; Reches, Z.

    2010-12-01

    High-speed shearing experiments on solid rock samples typically generate a gouge with sub-micron grain size that appears to control the frictional resistance at velocities approaching 1 m/s (Reches & Lockner, Nature, in press). We conducted experiments on Kasota dolomite samples and observed profound weakening (friction drops from ~0.8 to ~ 0.2) under earthquake conditions (up to slip-velocity ~ 0.95 m/s and normal stress 28.4 MPa). During these runs the experimental fault had T ≥ 800°C and developed a shining, dark surface. We report here analysis of such a surface with scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM analysis shows a slickensided gouge made up of particles all ≤ 50nm with a large fraction ≤ 20nm. The spacing of the slickenside striations is less than 1 µm. Over large areas of the slickensided surface the nanometric gouge has been replaced by an undeformed, interlocking crystalline pavement of 100-300 nm grain size. Qualitative chemical analysis of this pavement surface by energy-dispersive X-ray spectroscopy reveals only a weak carbon peak, suggesting that the dolomite has been decarbonated. The development of a “pavement” of grain size ~200 nm in our experiments is remarkably similar to the observations of Han et al. (JGR, 2010, Fig. 14(d)). However, their experiments either did not develop such a nanometric gouge or it was completely replaced by the coarser pavement. These present observations of nanometric gouge that recrystallizes during the short time interval of elevated temperature following termination of deformation are reminiscent of the nanometric “gouge” produced in very high-pressure experiments (1-14 GPa) that have failed by transformation-induced faulting during the olivine-spinel transformation (Green and Burnley, Nature, 1989; Green et al., Nature, 1990). In the high-pressure experiments, the gouge consists of a nanocrystalline aggregate of the spinel phase that flowed at very high strain

  13. Nanometric Finishing on Biomedical Implants by Abrasive Flow Finishing

    NASA Astrophysics Data System (ADS)

    Subramanian, Kavithaa Thirumalai; Balashanmugam, Natchimuthu; Shashi Kumar, Panaghra Veeraiah

    2016-01-01

    Abrasive flow finishing (AFF) is a non-conventional finishing technique that offers better accuracy, efficiency, consistency, economy in finishing of complex/difficult to machine materials/components and provides the possibility of effective automation as aspired by the manufacturing sector. The present study describes the finishing of a hip joint made of ASTM grade Co-Cr alloy by Abrasive Flow Machining (AFM) process. The major input parameters of the AFF process were optimized for achieving nanometric finishing of the component. The roughness average (Ra) values were recorded during experimentation using surface roughness tester and the results are discussed in detail. The surface finished hip joints were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and residual stress analysis using X-Ray Diffraction (XRD). The discussion lays emphasis on the significance, efficacy and versatile nature of the AFF process in finishing of bio-medical implants.

  14. Surface conductivity measurements in nanometric to micrometric foam films.

    PubMed

    Bonhomme, Oriane; Mounier, Anne; Simon, Gilles; Biance, Anne-Laure

    2015-05-20

    Foam films (a liquid lamella in air covered by surfactants) are tools of choice for nanofluidic characterization as they are intrinsically nanometric. Their size is indeed fixed by a balance between external pressure and particular molecular interactions in the vicinity of interfaces. To probe the exact nature of these interfaces, different characterizations can be performed. Among them, conductivity in confined systems is a direct probe of the electrostatic environment in the vicinity of the surface. Therefore, we designed a dedicated experiment to measure this conductivity in a cylindrical bubble coupled to interferometry for film thickness characterization. We then show that this conductivity depends on the surfactant nature. These conductivity measurements have been performed in an extremely confined system, the so called Newton black foam films. Unexpectedly in this case, a conductivity close to surface conductivity is recovered.

  15. Nanometric resolution magnetic resonance imaging methods for mapping functional activity in neuronal networks

    PubMed Central

    Boretti, Albert; Castelletto, Stefania

    2016-01-01

    This contribution highlights and compares some recent achievements in the use of k-space and real space imaging (scanning probe and wide-filed microscope techniques), when applied to a luminescent color center in diamond, known as nitrogen vacancy (NV) center. These techniques combined with the optically detected magnetic resonance of NV, provide a unique platform to achieve nanometric magnetic resonance imaging (MRI) resolution of nearby nuclear spins (known as nanoMRI), and nanometric NV real space localization. • Atomic size optically detectable spin probe. • High magnetic field sensitivity and nanometric resolution. • Non-invasive mapping of functional activity in neuronal networks. PMID:27144128

  16. Nanometric resolution magnetic resonance imaging methods for mapping functional activity in neuronal networks.

    PubMed

    Boretti, Albert; Castelletto, Stefania

    2016-01-01

    This contribution highlights and compares some recent achievements in the use of k-space and real space imaging (scanning probe and wide-filed microscope techniques), when applied to a luminescent color center in diamond, known as nitrogen vacancy (NV) center. These techniques combined with the optically detected magnetic resonance of NV, provide a unique platform to achieve nanometric magnetic resonance imaging (MRI) resolution of nearby nuclear spins (known as nanoMRI), and nanometric NV real space localization. •Atomic size optically detectable spin probe.•High magnetic field sensitivity and nanometric resolution.•Non-invasive mapping of functional activity in neuronal networks. PMID:27144128

  17. Nanometric resolution magnetic resonance imaging methods for mapping functional activity in neuronal networks.

    PubMed

    Boretti, Albert; Castelletto, Stefania

    2016-01-01

    This contribution highlights and compares some recent achievements in the use of k-space and real space imaging (scanning probe and wide-filed microscope techniques), when applied to a luminescent color center in diamond, known as nitrogen vacancy (NV) center. These techniques combined with the optically detected magnetic resonance of NV, provide a unique platform to achieve nanometric magnetic resonance imaging (MRI) resolution of nearby nuclear spins (known as nanoMRI), and nanometric NV real space localization. •Atomic size optically detectable spin probe.•High magnetic field sensitivity and nanometric resolution.•Non-invasive mapping of functional activity in neuronal networks.

  18. Atomic/molecular depth profiling of nanometric-metallized polymer thin films by secondary ion mass spectrometry.

    PubMed

    Téllez, Helena; Vadillo, José Miguel; Laserna, José Javier

    2010-02-01

    The capability of secondary ion mass spectrometry (SIMS) to perform atomic and molecular in-depth analysis in complex nanometric-metallized thin polymer films used to manufacture capacitors is demonstrated through three different case studies related to failure analysis. The excellent repeatability and sensitivity of the technique allow us to study the degradation process of the nanometric-metallized layer in the capacitor films and the accurate location of the metal-polymer interface. The analysis of the sample is challenging due to the extreme difference in conductivity between layers, and the reduced thickness of the metallization grown on top of a rough polymeric base. However, SIMS has provided reliable and reproducible results with relative standard deviation (RSD) values better than 1.5% in the metallic layer thickness estimation. The detailed information of atomic and molecular ion in-depth distributions provided by SIMS depth profiling has allowed the identification of different factors (demetallization, generation of interstitial oxide regions, and diffusion processes or modification in the metallization thickness) that can be directly related to the origin of the lack of performance of the mounted devices.

  19. Engineering nanometre-scale coherence in soft matter

    NASA Astrophysics Data System (ADS)

    Liu, Chaoren; Xiang, Limin; Zhang, Yuqi; Zhang, Peng; Beratan, David N.; Li, Yueqi; Tao, Nongjian

    2016-10-01

    Electronic delocalization in redox-active polymers may be disrupted by the heterogeneity of the environment that surrounds each monomer. When the differences in monomer redox-potential induced by the environment are small (as compared with the monomer-monomer electronic interactions), delocalization persists. Here we show that guanine (G) runs in double-stranded DNA support delocalization over 4-5 guanine bases. The weak interaction between delocalized G blocks on opposite DNA strands is known to support partially coherent long-range charge transport. The molecular-resolution model developed here finds that the coherence among these G blocks follows an even-odd orbital-symmetry rule and predicts that weakening the interaction between G blocks exaggerates the resistance oscillations. These findings indicate how sequence can be exploited to change the balance between coherent and incoherent transport. The predictions are tested and confirmed using break-junction experiments. Thus, tailored orbital symmetry and structural fluctuations may be used to produce coherent transport with a length scale of multiple nanometres in soft-matter assemblies, a length scale comparable to that of small proteins.

  20. Engineering nanometre-scale coherence in soft matter.

    PubMed

    Liu, Chaoren; Xiang, Limin; Zhang, Yuqi; Zhang, Peng; Beratan, David N; Li, Yueqi; Tao, Nongjian

    2016-10-01

    Electronic delocalization in redox-active polymers may be disrupted by the heterogeneity of the environment that surrounds each monomer. When the differences in monomer redox-potential induced by the environment are small (as compared with the monomer-monomer electronic interactions), delocalization persists. Here we show that guanine (G) runs in double-stranded DNA support delocalization over 4-5 guanine bases. The weak interaction between delocalized G blocks on opposite DNA strands is known to support partially coherent long-range charge transport. The molecular-resolution model developed here finds that the coherence among these G blocks follows an even-odd orbital-symmetry rule and predicts that weakening the interaction between G blocks exaggerates the resistance oscillations. These findings indicate how sequence can be exploited to change the balance between coherent and incoherent transport. The predictions are tested and confirmed using break-junction experiments. Thus, tailored orbital symmetry and structural fluctuations may be used to produce coherent transport with a length scale of multiple nanometres in soft-matter assemblies, a length scale comparable to that of small proteins. PMID:27657870

  1. Synthesis of bicyclo[4.n.1]alkanones.

    PubMed

    Montalt, Joaquin; Linker, Frédéric; Ratel, Frédéric; Miesch, Michel

    2004-10-01

    Cyclic beta-keto ester monoanions react with 1,4-dihalobutenes to give C-alkylated products which subsequently undergo a stereoselective SN2' O-alkylation reaction to yield functionalized enol ethers. When the starting material was ethyl cyclopentanone carboxylate, the C-alkylated product, treated with a base, directly afforded the functionalized bicyclo[4.2.1]nonanone. The enol ethers were submitted to a flash vacuum thermolysis (FVT) reaction to readily afford functionalized bicyclo[4.n.1]alkanones (n = 3, 4). This reaction sequence was applied to the synthesis of a functionalized tricyclo[7.4.1.0(1,5)]tetradecanone, which represents an analogue to the tricyclic core of ingenol. PMID:15387595

  2. Raman spectroscopy as probe of nanometre-scale strain variations in graphene

    PubMed Central

    Neumann, C.; Reichardt, S.; Venezuela, P.; Drögeler, M.; Banszerus, L.; Schmitz, M.; Watanabe, K.; Taniguchi, T.; Mauri, F.; Beschoten, B.; Rotkin, S. V.; Stampfer, C.

    2015-01-01

    Confocal Raman spectroscopy has emerged as a major, versatile workhorse for the non-invasive characterization of graphene. Although it is successfully used to determine the number of layers, the quality of edges, and the effects of strain, doping and disorder, the nature of the experimentally observed broadening of the most prominent Raman 2D line has remained unclear. Here we show that the observed 2D line width contains valuable information on strain variations in graphene on length scales far below the laser spot size, that is, on the nanometre-scale. This finding is highly relevant as it has been shown recently that such nanometre-scaled strain variations limit the carrier mobility in high-quality graphene devices. Consequently, the 2D line width is a good and easily accessible quantity for classifying the crystalline quality, nanometre-scale flatness as well as local electronic properties of graphene, all important for future scientific and industrial applications. PMID:26416349

  3. TOPICAL REVIEW Organic photovoltaics: principles and techniques for nanometre scale characterization

    NASA Astrophysics Data System (ADS)

    Nicholson, Patrick G.; Castro, Fernando A.

    2010-12-01

    The photoconversion efficiency of state-of-the-art organic solar cells has experienced a remarkable increase in the last few years, with reported certified efficiency values of up to 8.3%. This increase has been due to an improved understanding of the underlying physics, synthetic discovery and the realization of the pivotal role that morphological optimization plays. Advances in nanometre scale characterization have underpinned all three factors. Here we give an overview of the current understanding of the fundamental processes in organic photovoltaic devices, on optimization considerations and on recent developments in nanometre scale measuring techniques. Finally, recommendations for future developments from the perspective of characterization techniques are set forth.

  4. Molecular dynamic simulation for nanometric cutting of single-crystal face-centered cubic metals.

    PubMed

    Huang, Yanhua; Zong, Wenjun

    2014-01-01

    In this work, molecular dynamics simulations are performed to investigate the influence of material properties on the nanometric cutting of single crystal copper and aluminum with a diamond cutting tool. The atomic interactions in the two metallic materials are modeled by two sets of embedded atom method (EAM) potential parameters. Simulation results show that although the plastic deformation of the two materials is achieved by dislocation activities, the deformation behavior and related physical phenomena, such as the machining forces, machined surface quality, and chip morphology, are significantly different for different materials. Furthermore, the influence of material properties on the nanometric cutting has a strong dependence on the operating temperature. PMID:25426007

  5. Molecular dynamic simulation for nanometric cutting of single-crystal face-centered cubic metals

    PubMed Central

    2014-01-01

    In this work, molecular dynamics simulations are performed to investigate the influence of material properties on the nanometric cutting of single crystal copper and aluminum with a diamond cutting tool. The atomic interactions in the two metallic materials are modeled by two sets of embedded atom method (EAM) potential parameters. Simulation results show that although the plastic deformation of the two materials is achieved by dislocation activities, the deformation behavior and related physical phenomena, such as the machining forces, machined surface quality, and chip morphology, are significantly different for different materials. Furthermore, the influence of material properties on the nanometric cutting has a strong dependence on the operating temperature. PMID:25426007

  6. Molecular dynamic simulation for nanometric cutting of single-crystal face-centered cubic metals.

    PubMed

    Huang, Yanhua; Zong, Wenjun

    2014-01-01

    In this work, molecular dynamics simulations are performed to investigate the influence of material properties on the nanometric cutting of single crystal copper and aluminum with a diamond cutting tool. The atomic interactions in the two metallic materials are modeled by two sets of embedded atom method (EAM) potential parameters. Simulation results show that although the plastic deformation of the two materials is achieved by dislocation activities, the deformation behavior and related physical phenomena, such as the machining forces, machined surface quality, and chip morphology, are significantly different for different materials. Furthermore, the influence of material properties on the nanometric cutting has a strong dependence on the operating temperature.

  7. Theoretical study of the thermally induced structural fluctuations in sub-nanometre size gold clusters

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, José Manuel; Martín Montejano-Carrizales, Juan; Aguilera-Granja, Faustino; Posada-Amarillas, Álvaro

    2015-07-01

    A reactive potential model and the classical molecular dynamics method (RMD) have been used to study the structure and energetics of sub-nanometre size gold clusters through well-known structural models reported in the literature for AuN, with N = 19, 20 and 21 atoms. After several simulated-annealing simulations for temperatures up to 1500 K, the AuN clusters clearly evolve to well-defined structures at room temperature. For the studied gold clusters, the low-lying structures are single- and double-icosahedra with mobile atoms on the surface, in agreement with experimental results on sub-nanometre size gold clusters exhibiting shape oscillations at room temperature and also with those involved in the design of molecules based on gold superatoms [J.-I. Nishigaki, K. Koyasu, T. Tsukuda, Chem. Rec. 14, 897 (2014)]. The evolution of the structural stability of the AuN clusters under exceptional thermal conditions is analysed by comparing the size and temperature variations of the centrosymmetry parameter and the potential energy. A key understanding of the various possible structural changes undergone by these tiny particles is thus developed. The usefulness of the RMD to study nanometre or sub-nanometre size gold clusters is shown.

  8. Genetic characterization of avian influenza subtype H4N6 and H4N9 from live bird market, Thailand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A one year active surveillance program for influenza A viruses among avian species in a live-bird market (LBM) in Bangkok, Thailand was conducted in 2009. Out of 970 samples collected, influenza A virus subtypes H4N6 (n=2) and H4N9 (n=1), were isolated from healthy Muscovy ducks. All three viruses w...

  9. Modeling of the refractive index and composition of luminescent nanometric chlorinated-silicon nitride films with embedded Si-quantum dots

    NASA Astrophysics Data System (ADS)

    Rodríguez-Gómez, A.; Escobar-Alarcón, L.; Serna, R.; Cabello, F.; Haro-Poniatowski, E.; García-Valenzuela, A.; Alonso, J. C.

    2016-10-01

    The refractive index of nanometric (<100 nm) chlorinated-silicon nitride films with embedded silicon quantum dots, prepared by remote plasma enhanced chemical vapor deposition was investigated by spectroscopic ellipsometry. The complex refractive indexes and thicknesses of the films were obtained from the ellipsometric measurements using the Cauchy model. The chemical composition of the bulk of the films, including the hydrogen, chlorine, and oxygen content, was measured by elastic forward analysis (EFA) and X-ray photoelectron spectroscopy (XPS). The EFA and XPS results indicate that the films are composed of nearly stoichiometric silicon nitride (Si3N4) with different amounts of hydrogen, chlorine, and oxygen, and that their top surface is oxidized. Based on the composition results the refractive index of the films was fitted using the effective medium approximation considering the system: Si substrate + Si3N4 + Si + voids + top ultrathin oxidized surface layer.

  10. Interdiffusion in nanometric Fe/Ni multilayer films

    SciTech Connect

    Liu, JX; Barmak, K

    2015-03-01

    Fe (3.1 nm)/Ni (3.3 nm)](20) multilayer films were prepared by DC magnetron sputtering onto oxidized Si(100) substrates. The Fe and Ni layers were shown to both be face-centered cubic by x-ray diffraction. Interdiffusion of the Fe and Ni layers in the temperature range of 300-430 degrees C was studied by x-ray reflectivity. From the decay of the integral intensity of the superlattice peak, the activation energy and the pre-exponential term for the effective interdiffusion coefficient were determined as to 1.06 +/- 0.07 eV and 5 x 10(-10) cm(2)/s, respectively. The relevance of the measured interdiffusion coefficient to the laboratory timescale synthesis of L1(0) ordered FeNi as a rare-earth free permanent magnet is discussed. (C) 2015 American Vacuum Society.

  11. What holds paper together: nanometre scale exploration of bonding between paper fibres.

    PubMed

    Schmied, Franz J; Teichert, Christian; Kappel, Lisbeth; Hirn, Ulrich; Bauer, Wolfgang; Schennach, Robert

    2013-01-01

    Paper, a man-made material that has been used for hundreds of years, is a network of natural cellulosic fibres. To a large extent, it is the strength of bonding between these individual fibres that controls the strength of paper. Using atomic force microscopy, we explore here the mechanical properties of individual fibre-fibre bonds on the nanometre scale. A single fibre-fibre bond is loaded with a calibrated cantilever statically and dynamically until the bond breaks. Besides the calculation of the total energy input, time dependent processes such as creep and relaxation are studied. Through the nanometre scale investigation of the formerly bonded area, we show that fibrils or fibril bundles play a crucial role in fibre-fibre bonding because they act as bridging elements. With this knowledge, new fabrication routes can be deduced to increase the strength of an ancient product that is in fact an overlooked high-tech material.

  12. What holds paper together: Nanometre scale exploration of bonding between paper fibres

    PubMed Central

    Schmied, Franz J.; Teichert, Christian; Kappel, Lisbeth; Hirn, Ulrich; Bauer, Wolfgang; Schennach, Robert

    2013-01-01

    Paper, a man-made material that has been used for hundreds of years, is a network of natural cellulosic fibres. To a large extent, it is the strength of bonding between these individual fibres that controls the strength of paper. Using atomic force microscopy, we explore here the mechanical properties of individual fibre-fibre bonds on the nanometre scale. A single fibre-fibre bond is loaded with a calibrated cantilever statically and dynamically until the bond breaks. Besides the calculation of the total energy input, time dependent processes such as creep and relaxation are studied. Through the nanometre scale investigation of the formerly bonded area, we show that fibrils or fibril bundles play a crucial role in fibre-fibre bonding because they act as bridging elements. With this knowledge, new fabrication routes can be deduced to increase the strength of an ancient product that is in fact an overlooked high-tech material. PMID:23969946

  13. Transition from near-field thermal radiation to phonon heat conduction at sub-nanometre gaps.

    PubMed

    Chiloyan, Vazrik; Garg, Jivtesh; Esfarjani, Keivan; Chen, Gang

    2015-01-01

    When the separation of two surfaces approaches sub-nanometre scale, the boundary between the two most fundamental heat transfer modes, heat conduction by phonons and radiation by photons, is blurred. Here we develop an atomistic framework based on microscopic Maxwell's equations and lattice dynamics to describe the convergence of these heat transfer modes and the transition from one to the other. For gaps >1 nm, the predicted conductance values are in excellent agreement with the continuum theory of fluctuating electrodynamics. However, for sub-nanometre gaps we find the conductance is enhanced up to four times compared with the continuum approach, while avoiding its prediction of divergent conductance at contact. Furthermore, low-frequency acoustic phonons tunnel through the vacuum gap by coupling to evanescent electric fields, providing additional channels for energy transfer and leading to the observed enhancement. When the two surfaces are in or near contact, acoustic phonons become dominant heat carriers. PMID:25849305

  14. Interdiffusion in nanometric Fe/Ni multilayer films

    SciTech Connect

    Liu, Jiaxing Barmak, Katayun

    2015-03-15

    [Fe (3.1 nm)/Ni (3.3 nm)]{sub 20} multilayer films were prepared by DC magnetron sputtering onto oxidized Si(100) substrates. The Fe and Ni layers were shown to both be face-centered cubic by x-ray diffraction. Interdiffusion of the Fe and Ni layers in the temperature range of 300–430 °C was studied by x-ray reflectivity. From the decay of the integral intensity of the superlattice peak, the activation energy and the pre-exponential term for the effective interdiffusion coefficient were determined as to 1.06 ± 0.07 eV and 5 × 10{sup −10} cm{sup 2}/s, respectively. The relevance of the measured interdiffusion coefficient to the laboratory timescale synthesis of L1{sub 0} ordered FeNi as a rare-earth free permanent magnet is discussed.

  15. Spin waves damping in nanometre-scale magnetic materials (Review Article)

    NASA Astrophysics Data System (ADS)

    Krivoruchko, V. N.

    2015-09-01

    Spin dynamics in magnetic nanostructured materials is a topic of great current interest. To describe spin motions in such magnetic systems, the phenomenological Landau-Lifshitz (LL), or the LL-Gilbert (LLG), equation is widely used. Damping term is one of the dominant features of magnetization dynamics and plays an essential role in these equations of motion. The form of this term is simple; however, an important question arises whether it provides a proper description of the magnetization coupling to the thermal bath and the related magnetic fluctuations in the real nanometre-scale magnetic materials. It is now generally accepted that for nanostructured systems the damping term in the LL (LLG) equation fails to account for the systematics of the magnetization relaxation, even at the linear response level. In ultrathin films and nanostructured magnets particular relaxation mechanisms arise, extrinsic and intrinsic, which are relevant at nanometre-length scales, yet are not so efficient in bulk materials. These mechanisms of relaxation are crucial for understanding the magnetization dynamics that results in a linewidth dependence on the nanomagnet's size. We give an overview of recent efforts regarding the description of spin waves damping in nanostructured magnetic materials. Three types of systems are reviewed: ultrathin and exchange-based films, magnetic nanometre-scale samples and patterned magnetic structures. The former is an example of a rare case where consideration can be done analytically on microscopic footing. The latter two are typical samples when analytical approaches hardly have to be developed and numerical calculations are more fruitful. Progress in simulations of magnetization dynamics in nanometre-scale magnets gives hopes that a phenomenological approach can provide us with a realistic description of spin motions in expanding diverse of magnetic nanostructures.

  16. Fabrication and characterization of nanometric SiOx/SiOy multilayer structures obtained by LPCVD

    SciTech Connect

    Román-López, S.; Aceves-Mijares, M.; Pedraza-Chávez, J.; Carrillo-López, J.

    2014-05-15

    This work presents the fabrication of nanometric multilayer structures and their characterization by Atomic Force Microscopy, Photoluminescence and Fourier Transform Infra Red spectroscopy. The structures were deposited by Low Pressure Chemical Vapor Deposition (LPCVD). Three types of multilayer structure were fabricated. After the deposition some samples were annealed in N{sub 2} ambient for three hours. It was found that the structures keep the characteristics of each layer.

  17. Visible-Light-Induced Activity Control of Peroxidase Bound to Fe-Doped Titanate Nanosheets with Nanometric Lateral Dimensions.

    PubMed

    Kamada, Kai; Ito, Daiki; Soh, Nobuaki

    2015-10-21

    Catalytic performance of horseradish peroxidase (HRP) electrostatically adsorbed on nanometric and semiconducting Fe-doped titanate (FT) nanosheets was successfully manipulated by visible light illumination. A colloidal solution of FT with a narrow band gap corresponding to a visible light region was fabricated through a hydrolysis reaction of metals sources. HRP could be easily bound to the FT at pH = 4 through an electrostatic interaction between them, and the formed HRP-FT was utilized for the visible-light-driven enzymatic reaction. Under exposure to visible light with enough energy for band gap excitation of the FT, catalytic activity of HRP-FT was dramatically enhanced as compared with free (unbound) HRP and was simply adjusted by light intensity. In addition, wavelength dependence of an enzymatic reaction rate was analogous to an optical absorption spectrum of the FT. These results substantiated an expected reaction mechanism in which the photoenzymatic reaction was initiated by band gap excitation of FT followed by transferring holes generated in the valence band of irradiated FT to HRP. The excited HRP oxidized substrates (amplex ultrared: AUR) accompanied by two-electron reduction to regenerate the resting state. In addition, the catalytic activity was clearly switched by turning on and off the light source.

  18. Formation of nanometric HT-LiCoO(2) by a precipitation and aging process in an alcoholic solution.

    PubMed

    Larcher, Dominique; Delobel, Bruno; Dantras-Laffont, Lydia; Simon, Evelyne; Blach, Jean-François; Baudrin, Emmanuel

    2010-12-01

    In this paper, we detailed the formation/evolution of precipitates in alcoholic media containing Co(II+) and Li(+) species, together with the evolution of the composition and structure/texture of the resulting solid phases during the aging process at controlled constant temperature. While the end product is found to be well-crystallized HT-LiCoO(2), its formation is shown to result from a two-step process enlisting the initial fast precipitation of β-HCoO(2) and then its slow dissolution followed by recrystallization of the lithium-containing material. These results were obtained through combined X-ray diffraction, Raman and IR spectroscopy, elemental and oxidation-state analysis, and high-resolution transmission electron microscopy/selected-area electron diffraction observations. Depending on the cationic concentration, the size of the precipitated material can be controlled within the nanometric range. The electrochemical performances of these aged materials are slightly improved compared to those of the directly precipitated ones that we previously reported. The main limitation of these materials remains the presence of surface protons.

  19. Lithium Storage Properties of a Bioinspired 2-Line Ferrihydrite: A Silicon-Doped, Nanometric, and Amorphous Iron Oxyhydroxide.

    PubMed

    Hashimoto, Hideki; Nishiyama, Yuta; Ukita, Masahiro; Sakuma, Ryo; Nakanishi, Makoto; Fujii, Tatsuo; Takada, Jun

    2015-08-01

    Inspired by a nanometric iron-based oxide material of bacterial origin, silicon (Si)-doped iron oxyhydroxide nanoparticles or 2-line ferrihydrites (2Fhs) were prepared and their lithium (Li) storage properties were investigated. The structures of the Si-doped 2Fhs strongly depended on the Si molar ratio [x = Si/(Fe + Si)] whose long-range atomic ordering gradually vanished as the Si molar ratio increased, with a structural change from nanocrystalline to amorphous at x = 0.30. The most striking properties were observed for the sample with x = 0.30. Over the voltage range of 1.5-4.0 V at a current rate of 500 mA/g, this material exhibited a relatively high reversible capacity of ∼100 mAh/g, which was four times greater than that of the Si-free 2Fh and indicated a good rate capability and cyclability. The large capacity and good rate and cycle performances are presumably because of the amorphous structure and the strong and stabilizing covalent Si-O bonds, respectively. The minor amount of Si(4+) in the structure of the iron oxyhydroxides is considered to improve the electrochemical properties. Use of more appropriate doping elements and fabrication of more appropriate nanostructures could drastically improve the Li storage properties of the developed bioinspired material.

  20. Influence of size-corrected bound-electron contribution on nanometric silver dielectric function. Sizing through optical extinction spectroscopy

    NASA Astrophysics Data System (ADS)

    Santillán, J. M. J.; Videla, F. A.; Fernández van Raap, M. B.; Muraca, D.; Scaffardi, L. B.; Schinca, D. C.

    2013-10-01

    The study of metal nanoparticles (NPs) is of great interest due to their ability to enhance optical fields on the nanometric scale, which makes them interesting for various applications in several fields of science and technology. In particular, their optical properties depend on the dielectric function of the metal, its size, shape and surrounding environment. This work analyses the contributions of free and bound electrons to the complex dielectric function of spherical silver NPs and their influence on the optical extinction spectra. The contribution of free electrons is usually corrected for particle size under 10 nm, introducing a modification of the damping constant to account for the extra collisions with the particle's boundary. For the contribution of bound electrons, we considered the interband transitions from the d-band to the conduction band including the size dependence of the electronic density states for radii below 2 nm. Bearing in mind these specific modifications, it was possible to determine optical and band energy parameters by fitting the bulk complex dielectric function. The results obtained from the optimum fit are: Kbulk = 2 × 1024 (coefficient for bound-electron contribution), Eg = 1.91 eV (gap energy), EF = 4.12 eV (Fermi energy), and γb = 1.5 × 1014 Hz (damping constant for bound electrons). Based on this size-dependent dielectric function, extinction spectra of silver particles in the nanometric-subnanometric radius range can be calculated using Mie's theory, and its size behaviour analysed. These studies are applied to fit experimental extinction spectrum of very small spherical particles fabricated by fs laser ablation of a solid target in water. From the fitting, the structure and size distribution of core radius and shell thickness of the colloidal suspension could be determined. The spectroscopic results suggest that the colloidal suspension is composed by two types of structures: bare core and core-shell. The former is composed

  1. Osteogenic lineage restriction by osteoprogenitors cultured on nanometric grooved surfaces: the role of focal adhesion maturation.

    PubMed

    Cassidy, John W; Roberts, Jemma N; Smith, Carol-Anne; Robertson, Mary; White, Kate; Biggs, Manus J; Oreffo, Richard O C; Dalby, Matthew J

    2014-02-01

    The differentiation of progenitor cells is dependent on more than biochemical signalling. Topographical cues in natural bone extracellular matrix guide cellular differentiation through the formation of focal adhesions, contact guidance, cytoskeletal rearrangement and ultimately gene expression. Osteoarthritis and a number of bone disorders present as growing challenges for our society. Hence, there is a need for next generation implantable devices to substitute for, or guide, bone repair in vivo. Cellular responses to nanometric topographical cues need to be better understood in vitro in order to ensure the effective and efficient integration and performance of these orthopedic devices. In this study, the FDA-approved plastic polycaprolactone was embossed with nanometric grooves and the response of primary and immortalized osteoprogenitor cells observed. Nanometric groove dimensions were 240 nm or 540 nm deep and 12.5 μm wide. Cells cultured on test surfaces followed contact guidance along the length of groove edges, elongated along their major axis and showed nuclear distortion; they formed more focal complexes and lower proportions of mature adhesions relative to planar controls. Down-regulation of the osteoblast marker genes RUNX2 and BMPR2 in primary and immortalized cells was observed on grooved substrates. Down-regulation appeared to directly correlate with focal adhesion maturation, indicating the involvement of ERK 1/2 negative feedback pathways following integrin-mediated FAK activation. PMID:24252447

  2. Structural changes of polysulfone membrane use for hemodialysis in the consecutive regime: nanometric analysis by AFM

    NASA Astrophysics Data System (ADS)

    Batina, Nikola; Acosta García, Ma. Cristina; Avalos Pérez, Angélica; Alberto Ramírez, Mario; Franco, Martha; Pérez Gravas, Héctor; Cadena Méndez, Miguel

    2013-08-01

    Nowadays, the hemodialytic treatment of patients with either acute or chronic renal failure has been improved by promoting biocompatibility in the use of new materials and improve membrane surface characteristics. Low and high flux polysulfone membranes (PM) used in dialysis and ultra filtration have been studied in order to understand the geometry and surface chemistry of the pores at inner (nanometric) and outer (micrometric) membrane parts. The surface changes of polysulfone cartridge membrane (PM) during different number of consecutive reuse trials: after 1st, 10th and 23th times of use. The morphology of the hollow fibers surfaces was studied by means of the atomic force microscopy (AFM) imaging and the surface roughness analysis. The roughness of both inner and outer part of PM surface increases with numbers of reuse trails. Thus, small and medium size pores were wiped out when the number of uses changed from zero to 23 on the outer surface. The pore density decreases. The inner part of membrane shows some nanometric size deformation in forms of new openings and raptures. The AFM analysis show differences in the PM morphology at the nanometric level, not previously revealed, which could be important in the evaluation of the PM.

  3. Nanometre-scale evidence for interfacial dissolution-reprecipitation control of silicate glass corrosion.

    PubMed

    Hellmann, Roland; Cotte, Stéphane; Cadel, Emmanuel; Malladi, Sairam; Karlsson, Lisa S; Lozano-Perez, Sergio; Cabié, Martiane; Seyeux, Antoine

    2015-03-01

    Silicate glasses are durable solids, and yet they are chemically unstable in contact with aqueous fluids-this has important implications for numerous industrial applications related to the corrosion resistance of glasses, or the biogeochemical weathering of volcanic glasses in seawater. The aqueous dissolution of synthetic and natural glasses results in the formation of a hydrated, cation-depleted near-surface alteration zone and, depending on alteration conditions, secondary crystalline phases on the surface. The long-standing accepted model of glass corrosion is based on diffusion-coupled hydration and selective cation release, producing a surface-altered zone. However, using a combination of advanced atomic-resolution analytical techniques, our data for the first time reveal that the structural and chemical interface between the pristine glass and altered zone is always extremely sharp, with gradients in the nanometre to sub-nanometre range. These findings support a new corrosion mechanism, interfacial dissolution-reprecipitation. Moreover, they also highlight the importance of using analytical methods with very high spatial and mass resolution for deciphering the nanometre-scale processes controlling corrosion. Our findings provide evidence that interfacial dissolution-reprecipitation may be a universal reaction mechanism that controls both silicate glass corrosion and mineral weathering.

  4. Energy dependent track structure parametrisations for protons and carbon ions based on nanometric simulations

    NASA Astrophysics Data System (ADS)

    Alexander, Frauke; Villagrasa, Carmen; Rabus, Hans; Wilkens, Jan J.

    2015-09-01

    The BioQuaRT project within the European Metrology Research Programme aims at correlating ion track structure characteristics with the biological effects of radiation and develops measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigate methods to translate track-structure quantities derived on a nanometre scale to macroscopic dimensions. Input data sets were generated by simulations of ion tracks of protons and carbon ions in liquid water using the Geant 4 Monte Carlo toolkit with the Geant4-DNA processes. Based on the energy transfer points - recorded with nanometre resolution - we investigated parametrisations of overall properties of ion track structure. Three different track structure parametrisations have been developed using the distances to the 10 next neighbouring ionisations, the radial energy distribution and ionisation cluster size distributions. These parametrisations of nanometric track structure build a basis for deriving biologically relevant mean values which are essential in the clinical situation where each voxel is exposed to a mixed radiation field. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene Surdutovich.

  5. Geometry-induced electrostatic trapping of nanometric objects in a fluid.

    PubMed

    Krishnan, Madhavi; Mojarad, Nassiredin; Kukura, Philipp; Sandoghdar, Vahid

    2010-10-01

    The ability to trap an object-whether a single atom or a macroscopic entity-affects fields as diverse as quantum optics, soft condensed-matter physics, biophysics and clinical medicine. Many sophisticated methodologies have been developed to counter the randomizing effect of Brownian motion in solution, but stable trapping of nanometre-sized objects remains challenging. Optical tweezers are widely used traps, but require sufficiently polarizable objects and thus are unable to manipulate small macromolecules. Confinement of single molecules has been achieved using electrokinetic feedback guided by tracking of a fluorescent label, but photophysical constraints limit the trap stiffness and lifetime. Here we show that a fluidic slit with appropriately tailored topography has a spatially modulated electrostatic potential that can trap and levitate charged objects in solution for up to several hours. We illustrate this principle with gold particles, polymer beads and lipid vesicles with diameters of tens of nanometres, which are all trapped without external intervention and independently of their mass and dielectric function. The stiffness and stability of our electrostatic trap is easily tuned by adjusting the system geometry and the ionic strength of the solution, and it lends itself to integration with other manipulation mechanisms. We anticipate that these features will allow its use for contact-free confinement of single proteins and macromolecules, and the sorting and fractionation of nanometre-sized objects or their assembly into high-density arrays.

  6. Nanometric Graphene Oxide Framework Membranes with Enhanced Heavy Metal Removal via Nanofiltration.

    PubMed

    Zhang, Yu; Zhang, Sui; Chung, Tai-Shung

    2015-08-18

    A novel dual-modification strategy, including (1) the cross-linking and construction of a GO framework by ethylenediamine (EDA) and (2) the amine-enrichment modification by hyperbranched polyethylenimine (HPEI), has been proposed to design stable and highly charged GO framework membranes with the GO selective layer thickness of 70 nm for effective heave metal removal via nanofiltration (NF). Results from sonication experiments and positron annihilation spectroscopy confirmed that EDA cross-linking not only enhanced structural stability but also enlarged the nanochannels among the laminated GO nanosheets for higher water permeability. HPEI 60K was found to be the most effective post-treatment agent that resulted in GO framework membranes with a higher surface charge and lower transport resistance. The newly developed membrane exhibited a high pure water permeability of 5.01 L m(-2) h(-1) bar(-1) and comparably high rejections toward Mg(2+), Pb(2+), Ni(2+), Cd(2+), and Zn(2+). These results have demonstrated the great potential of GO framework materials in wastewater treatment and may provide insights for the design and fabrication of the next generation two-dimensional (2D)-based NF membranes. PMID:26197200

  7. Potential for 4-n-nonylphenol biodegradation in stream sediments

    USGS Publications Warehouse

    Bradley, P.M.; Barber, L.B.; Kolpin, D.W.; McMahon, P.B.; Chapelle, F.H.

    2008-01-01

    The potential for in situ biodegradation of 4-nonylphenol (4-NP) was investigated in three hydrologically distinct streams impacted by wastewater treatment plants (WWTPs) in the United States. Microcosms were prepared with sediments from each site and amended with [U-ring-14C]4-n-nonylphenol (4-n-NP) as a model test substrate. Microcosms prepared with sediment collected upstream of the WWTP outfalls and incubated under oxic conditions showed rapid and complete mineralization of [U-ring-14C]4- n-NP to 14CO2 in all three systems. In contrast, no mineralization of [U-ring-14C]4-n-NP was observed in these sediments under anoxic (methanogenic) conditions. The initial linear rate of [U-ring-14C]4-n-NP mineralization in sediments from upstream and downstream of the respective WWTP outfalls was inversely correlated with the biochemical oxygen demand (BOD) of the streambed sediments. These results suggest that the net supply of dissolved oxygen to streambed sediments is a key determinant of the rate and extent of 4-NP biodegradation in stream systems. In the stream systems considered by the present study, dissolved oxygen concentrations in the overlying water column (8–10 mg/L) and in the bed sediment pore water (1–3 mg/L at a depth of 10 cm below the sediment–water interface) were consistent with active in situ 4-NP biodegradation. These results suggest WWTP procedures that maximize the delivery of dissolved oxygen while minimizing the release of BOD to stream receptors favor efficient biodegradation of 4-NP contaminants in wastewater-impacted stream environments.

  8. Sub-nanometrically resolved chemical mappings of quantum-cascade laser active regions

    NASA Astrophysics Data System (ADS)

    Pantzas, Konstantinos; Beaudoin, Grégoire; Patriarche, Gilles; Largeau, Ludovic; Mauguin, Olivia; Pegolotti, Giulia; Vasanelli, Angela; Calvar, Ariane; Amanti, Maria; Sirtori, Carlo; Sagnes, Isabelle

    2016-05-01

    A procedure that produces sub-nanometrically resolved chemical mappings of MOCVD-grown InGaAs/InAlAs/InP quantum cascade lasers is presented. The chemical mappings reveal that, although the structure is lattice-matched to InP, the InAlAs barriers do not attain the nominal aluminum content—48%—and are, in fact, InGaAlAs quaternaries. This information is used to adjust the aluminum precursor flow and fine-tune the composition of the barriers, resulting in a significant improvement of the fabricated lasers.

  9. Processing, Application and Characterization of (Ultra)fine and Nanometric Materials in Energetic Compositions

    NASA Astrophysics Data System (ADS)

    van der Heijden, A. E. D. M.; Bouma, R. H. B.; Carton, E. P.; Martinez Pacheco, M.; Meuken, B.; Webb, R.; Zevenbergen, J. F.

    2006-07-01

    The energetic materials research at TNO Defence, Security and Safety, The Netherlands is focusing at the development and characterization of explosives (insensitive munitions), gun/rocket propellants and pyrotechnic compositions and their ingredients. The application of reactive, (ultra)fine and nanometric materials in these compositions has gained increased interest over the past few years. Current research topics focus on the processing, application and characterization of (1) (ultra)fine energetic crystals and composite nano-clusters in plastic bonded explosives, (2) metastable intermolecular composites (MICs) and (3) self-propagating high-temperature synthesis (SHS). In this paper these topics will be highlighted in more detail.

  10. Processing, application and characterization of ultrafine and nanometric materials in energetic compositions

    NASA Astrophysics Data System (ADS)

    van der Heijden, Antoine

    2005-07-01

    The energetic materials research at TNO Defence, Security and Safety, The Netherlands is focusing at the development and characterization of explosives (insensitive munitions), gun/rocket propellants and pyrotechnic compositions and their ingredients. The application of reactive, ultrafine and nanometric materials in these compositions has gained increased interest over the past few years. Current research topics focus on the processing, application and characterization of (1) ultrafine energetic crystals and composite nano-clusters in plastic bonded explosives, (2) metastable intermolecular composites (MICs) and (3) self-propagating high-temperature synthesis (SHS). In this paper several of these topics will be highlighted in more detail.

  11. Laser pyrolysis fabrication of ferromagnetic gamma'-Fe4N and FeC nanoparticles

    NASA Technical Reports Server (NTRS)

    Grimes, C. A.; Qian, D.; Dickey, E. C.; Allen, J. L.; Eklund, P. C.

    2000-01-01

    Using the laser pyrolysis method, single phase gamma'-Fe4N nanoparticles were prepared by a two step method involving preparation of nanoscale iron oxide and a subsequent gas-solid nitridation reaction. Single phase Fe3C and Fe7C3 could be prepared by laser pyrolysis from Fe(CO)5 and 3C2H4 directly. Characterization techniques such as XRD, TEM and vibrating sample magnetometer were used to measure phase structure, particle size and magnetic properties of these nanoscale nitride and carbide particles. c2000 American Journal of Physics.

  12. Engineering a Biocompatible Scaffold with Either Micrometre or Nanometre Scale Surface Topography for Promoting Protein Adsorption and Cellular Response

    PubMed Central

    Le, Xuan; Poinern, Gérrard Eddy Jai; Ali, Nurshahidah; Berry, Cassandra M.; Fawcett, Derek

    2013-01-01

    Surface topographical features on biomaterials, both at the submicrometre and nanometre scales, are known to influence the physicochemical interactions between biological processes involving proteins and cells. The nanometre-structured surface features tend to resemble the extracellular matrix, the natural environment in which cells live, communicate, and work together. It is believed that by engineering a well-defined nanometre scale surface topography, it should be possible to induce appropriate surface signals that can be used to manipulate cell function in a similar manner to the extracellular matrix. Therefore, there is a need to investigate, understand, and ultimately have the ability to produce tailor-made nanometre scale surface topographies with suitable surface chemistry to promote favourable biological interactions similar to those of the extracellular matrix. Recent advances in nanoscience and nanotechnology have produced many new nanomaterials and numerous manufacturing techniques that have the potential to significantly improve several fields such as biological sensing, cell culture technology, surgical implants, and medical devices. For these fields to progress, there is a definite need to develop a detailed understanding of the interaction between biological systems and fabricated surface structures at both the micrometre and nanometre scales. PMID:23533416

  13. Degradation of 4-n-nonylphenol under nitrate reducing conditions

    PubMed Central

    Viñas, Marc; Grotenhuis, Tim; Rijnaarts, Huub H. M.; Langenhoff, Alette A. M.

    2010-01-01

    Nonylphenol (NP) is an endocrine disruptor present as a pollutant in river sediment. Biodegradation of NP can reduce its toxicological risk. As sediments are mainly anaerobic, degradation of linear (4-n-NP) and branched nonylphenol (tNP) was studied under methanogenic, sulphate reducing and denitrifying conditions in NP polluted river sediment. Anaerobic bioconversion was observed only for linear NP under denitrifying conditions. The microbial population involved herein was further studied by enrichment and molecular characterization. The largest change in diversity was observed between the enrichments of the third and fourth generation, and further enrichment did not affect the diversity. This implies that different microorganisms are involved in the degradation of 4-n-NP in the sediment. The major degrading bacteria were most closely related to denitrifying hexadecane degraders and linear alkyl benzene sulphonate (LAS) degraders. The molecular structures of alkanes and LAS are similar to the linear chain of 4-n-NP, this might indicate that the biodegradation of linear NP under denitrifying conditions starts at the nonyl chain. Initiation of anaerobic NP degradation was further tested using phenol as a structure analogue. Phenol was chosen instead of an aliphatic analogue, because phenol is the common structure present in all NP isomers while the structure of the aliphatic chain differs per isomer. Phenol was degraded in all cases, but did not affect the linear NP degradation under denitrifying conditions and did not initiate the degradation of tNP and linear NP under the other tested conditions. PMID:20640878

  14. Phase transformation and nanometric flow cause extreme weakening during fault slip

    NASA Astrophysics Data System (ADS)

    Green, H. W., II; Shi, F.; Bozhilov, K.; Xia, G.; Reches, Z.

    2015-06-01

    Earthquake instability requires fault weakening during slip. The mechanism of this weakening is central to understanding earthquake sliding and, in many cases, has been attributed to fluids. It is also unclear why major faults such as the San Andreas Fault do not exhibit significant thermal anomalies due to shear heating during sliding and whether or not fault rocks that have been melted--pseudotachylytes--are rare. High-speed friction experiments on a wide variety of rock types have shown that they all exhibit extreme weakening and that the sliding surface is nanometric and contains phases not present at the start. Here we use electron microscopy to examine these two key observations in high-speed friction experiments and compare them with high-pressure faulting experiments. We show that phase transformations occur in both cases and that they are associated with profound weakening. However, fluid is not necessary for such weakening; the nanometric fault filling is inherently weak at seismic sliding rates and it flows by grain boundary sliding. These observations suggest that pseudotachylytes are rare in nature because shear-heating-induced endothermic reactions in fault zones prevent temperature rise to melting. Microstructures preserved in the Punchbowl Fault, an ancestral branch of the San Andreas Fault, suggest similar processes during natural faulting and offer an explanation for the lack of a thermal aureole around major faults.

  15. Supercritical CO2 generation of nanometric structure from Ocimum basilicum mucilage prepared for pharmaceutical applications.

    PubMed

    Akbari, Iman; Ghoreishi, Seyyed M; Habibi, Neda

    2015-04-01

    Plant-derived polymers are widely used in the pharmaceutical industry due to their emollient, lack of toxicity, and irritating nature and low cost. In this work, basil seed mucilage was dried using supercritical carbon dioxide phase inversion technique to form a nanometric structure. The obtained polymeric structures were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) method, and Fourier transform infrared spectroscopy (FTIR) and compared with the oven-derived sample group. It was demonstrated that the product morphology could be controlled by altering the composition of methanol which functioned as the co-solvent in the nonsolvent stream. The most homogeneous product (60-nm mean pore size diameter, 78 m(2)/g BET surface area with no agglomeration) was obtained with 2.5% methanol. The FTIR data showed that the presence of hydroxyl and carboxyl groups suggested the bioadhesive property of basil seed mucilage was good and many active pharmaceutical compounds might be loaded to the resultant nanometric structure to enhance drug release. Furthermore, the FTIR analyses indicated that the nature of the final product did not change during the supercritical drying procedure.

  16. Local weighting of nanometric track structure properties in macroscopic voxel geometries for particle beam treatment planning

    NASA Astrophysics Data System (ADS)

    Alexander, F.; Villagrasa, C.; Rabus, H.; Wilkens, J. J.

    2015-12-01

    The research project BioQuaRT within the European Metrology Research Programme aimed at correlating ion track structure characteristics with the biological effects of radiation and developed measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigated methods to translate track-structure quantities derived on a nanometre scale to macroscopic dimensions. Here we make use of parameterizations that link the energy of the projectile to the ionization pattern of the track using nanodosimetric ionization cluster size distributions. They were defined with data generated by simulations of ion tracks in liquid water using the Geant4 Monte Carlo toolkit with the Geant4-DNA processes. For the clinical situation with a mixed radiation field, where particles of various energies hit a cell from several directions, we have to find macroscopic relevant mean values. They can be determined by appropriate local weighting functions for the identified parameterization. We show that a stopping power weighted mean value of the mentioned track structure properties can describe the overall track structure in a cell exposed to a mixed radiation field. The parameterization, together with the presented stopping power weighting approach, show how nanometric track structure properties could be integrated into treatment planning systems without the need to perform time consuming simulations on the nanometer level for each individual patient.

  17. Silica hybrid particles with nanometre polymer shells and their influence on the toughening of polypropylene.

    PubMed

    Zheng, Jing-Zhi; Zhou, Xing-Ping; Xie, Xiao-Lin; Mai, Yiu-Wing

    2010-10-01

    Colloidal silica particles were synthesized by the sol-gel process and then modified with 3-methacryloxypropyltrimethoxysilane (γ-MPS) to induce vinyl groups on the surface of the silica particles. By means of in situ emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA), a series of core-shell silica hybrid particles with nanometre poly(MMA-co-BA) shells were fabricated, which were subsequently compounded with isotactic polypropylene (PP) in the molten state. Upon increasing the feed silica : monomer ratio from 1 : 1 to 4 : 1, the poly(MMA-co-BA) shell thickness on the silica core decreased from 50 nm to 10 nm. Owing to the existence of the nanometre poly(MMA-co-BA) shells, the silica hybrid particles were monodispersed in the PP matrix, causing homogeneous debonding at the PP/silica interface, followed by plastic void expansion and matrix shear yielding during impact fracture. These deformation mechanisms greatly toughened the PP-silica composites. A critical shell thickness of poly(MMA-co-BA) was needed to achieve optimal mechanical properties. That is, when the polymer shell thickness was 15 nm, compared to pure PP, the impact toughness of the PP-silica composite was more than doubled with little degradation of tensile strength. PMID:20730152

  18. Breakup of Thin Liquid Filaments on Partially Wetting Substrates: from Micrometric to Nanometric Scales

    NASA Astrophysics Data System (ADS)

    Diez, Javier A.; González, Alejandro G.

    2016-04-01

    We present theoretical and experimental results regarding the instability of a thin liquid film in the form a long filament sitted on a solid substrate. We consider this problem in two different scenarios, namely, at submillimetric and nanometric scales, and we study their free surface instability. In the first scale, we take into account the effects due to surface tension and gravity, while in the smaller scale, we add intermolecular interaction and neglect gravity. The flows are modeled within the long wave approximation, which leads to a nonlinear fourth-order differential equation for the fluid thickness. This model equation also includes the partial wetting condition between the liquid and the solid. In the theoretical models, we analyze the linear stability of the equilibrium configurations. The linear stability analyses lead to eigenvalue problems that are solved using pseudo spectral methods in the submillimetric case, and finite differences in the nanoscale. Whenever possible, the theoretical results are compared with experiments performed on a submillimetric scale (silicon oils on glass), as well as on nanometric scale (nickel films melted by laser irradiation on SiO2 substrates).

  19. Sensing nanometric displacement of a micro-/nano-fiber induced by optical forces by use of white light interferometry

    NASA Astrophysics Data System (ADS)

    Qiu, Weiqia; Huang, Hankai; Yu, Jianhui; Dong, Huazhuo; Chen, Zhe; Lu, Huihui

    2015-07-01

    Sensing the nanometric displacement of a micro-/nano-fiber induced by optical forces is a key technology to study optical forces and optical momentum. When the gap between a micro-/nano-fiber and glass substrate becomes down to micrometer scale or less, a white light interference was observed. The gap changes when optical force arising from the propagating pump light along the micro-/nano-fiber causes a transversal nanometric displacement of a micro-/nanofiber, resulting in movement of the interferometric fringes. Therefore this movement of the interferometric fringes can be used to sense the nanometric displacement of the micro-/nano-fiber induced by optical forces. Experimental results show that the resolutions of this method can reach 7.27nm/pixel for tilted angle 0.8o between the micro-/nano-fiber and substrate. It is concluded that the white light interferometry method is suitable for measuring the weak optical force.

  20. Nanowires of Fe/multi-walled carbon nanotubes and nanometric thin films of Fe/MgO

    SciTech Connect

    Newman, Alexander; Khatiwada, Suman; Neupane, Suman; Seifu, Dereje

    2015-04-14

    We observed that nanowires of Fe grown in the lumens of multi-walled carbon nanotubes required four times higher magnetic field strength to reach saturation compared to planar nanometric thin films of Fe on MgO(100). Nanowires of Fe and nanometric thin films of Fe both exhibited two fold magnetic symmetries. Structural and magnetic properties of 1-dimensional nanowires and 2-dimensional nanometric films were studied by several magnetometery techniques. The θ-2θ x-ray diffraction measurements showed that a (200) peak of Fe appeared on thin film samples deposited at higher substrate temperatures. In these samples prepared at higher temperatures, lower coercive field and highly pronounced two-fold magnetic symmetry were observed. Our results show that maximum magnetocrystalline anisotropy occurred for sample deposited at 100 °C and it decreased at higher deposition temperatures.

  1. Nanowires of Fe/multi-walled carbon nanotubes and nanometric thin films of Fe/MgO

    NASA Astrophysics Data System (ADS)

    Newman, Alexander; Khatiwada, Suman; Neupane, Suman; Seifu, Dereje

    2015-04-01

    We observed that nanowires of Fe grown in the lumens of multi-walled carbon nanotubes required four times higher magnetic field strength to reach saturation compared to planar nanometric thin films of Fe on MgO(100). Nanowires of Fe and nanometric thin films of Fe both exhibited two fold magnetic symmetries. Structural and magnetic properties of 1-dimensional nanowires and 2-dimensional nanometric films were studied by several magnetometery techniques. The θ-2θ x-ray diffraction measurements showed that a (200) peak of Fe appeared on thin film samples deposited at higher substrate temperatures. In these samples prepared at higher temperatures, lower coercive field and highly pronounced two-fold magnetic symmetry were observed. Our results show that maximum magnetocrystalline anisotropy occurred for sample deposited at 100 °C and it decreased at higher deposition temperatures.

  2. Laser generation of elliptical nanometre and sub-nanometre bump arrays on NiP/Al data storage disks and their effect on stiction performance.

    PubMed

    Pena, A A; Wang, Z B; Zhang, J; Wu, N E; Li, L

    2011-09-01

    Elliptical nano-bumps on nickel-phosphorus coated aluminium (NiP/Al) hard disks were fabricated by a laser texturing system (maximum power 8 W, maximum frequency 300 kHz). By carefully selecting the level of laser power attenuation and defocus offset distance, bump height can be controlled below 6 nm and down to the sub-nanometre scale. This type of laser-induced texture (elliptical shape) on a disk surface is expected to provide better control of the stiction force along with the smallest separation distance between the head slider and the disk. Quantitative modelling based on the classical Hertzian theory for elliptic contacts has been carried out with the purpose of predicting the stiction behaviour of the presented elliptical shaped sub-10 nm bumps. It has been found that an elliptical shape not only reduces the overall stiction performance of the laser texturing zone (LZT) compared to the conventional circular shape but also extends the occurrence of the 'stiction wall' towards the sub-10 nm regime for ultra-low-glide applications. PMID:21836329

  3. Innovative Powder Processing of Oxide Dispersion Strengthened ODS Ferritic Stainless Steels

    SciTech Connect

    Rieken, Joel; Anderson, Iver; Kramer, Matthew

    2011-04-01

    An innovative gas atomization reaction synthesis technique was employed as a viable method to dramatically lower the processing cost for precursor oxide dispersion forming ferritic stainless steel powders (i.e., Fe-Cr-(Hf,Ti)-Y). During this rapid solidification process the atomized powders were enveloped by a nano-metric Cr-enriched metastable oxide film. Elevated temperature heat treatment was used to dissociate this metastable oxide phase through oxygen exchange reactions with Y-(Hf,Ti) enriched intermetallic compound precipitates. These solid state reactions resulted in the formation of highly stable nano-metric mixed oxide dispersoids (i.e., Y-Ti-O or Y-Hf-O) throughout the alloy microstructure. Subsequent high temperature (1200 C) heat treatments were used to elucidate the thermal stability of each nano-metric oxide dispersoid phase. Transmission electron microscopy coupled with X-ray diffraction was used to evaluate phase evolution within the alloy microstructure.

  4. Probing variations of the Rashba spin-orbit coupling at the nanometre scale

    NASA Astrophysics Data System (ADS)

    Bindel, Jan Raphael; Pezzotta, Mike; Ulrich, Jascha; Liebmann, Marcus; Sherman, Eugene Ya.; Morgenstern, Markus

    2016-10-01

    As the Rashba effect is an electrically tunable spin-orbit interaction, it could form the basis for a multitude of applications, such as spin filters, spin transistors and quantum computing using Majorana states in nanowires. Moreover, this interaction can determine the spin dephasing and antilocalization phenomena in two dimensions. However, the real space pattern of the Rashba parameter, which critically influences spin transistors using the spin-helix state and the otherwise forbidden electron backscattering in topologically protected channels, is difficult to probe. Here, we map this pattern down to nanometre length scales by measuring the spin splitting of the lowest Landau level using scanning tunnelling spectroscopy. We reveal strong fluctuations correlated with the local electrostatic potential for an InSb inversion layer with a large Rashba coefficient (~1 eV Å). This type of Rashba field mapping enables a more comprehensive understanding of its fluctuations, which might be decisive towards robust semiconductor-based spintronic devices.

  5. Nano-metric Dust Particles as a Hardly Detectable Component of the Interplanetary Dust Cloud

    NASA Astrophysics Data System (ADS)

    Simonia, I.; Nabiyev, Sh.

    2015-09-01

    The present work introduces the hypothesis of existence of a hardly detectable component of the interplanetary dust cloud and demonstrates that such a component is a dust formation consisting of the dust particles of nano-metric dimensions. This work describes the main physical properties of such a kind of nano-dust, and its possible chemical and mineralogical peculiarities proposes new explanations related to reddening of the dynamically cold transneptunian objects on account of scattering their light by nano-dust of the hardly detectable component of the interplanetary dust cloud. We propose the relation for the coefficient of absorption by the nano-dust and provide results of the statistical analysis of the TNO color index-orbital inclinations. We also present a critical assessment of the proposed hypothesis.

  6. Thin films of Prussian blue: sequential assembly, patterning and electron transport properties at the nanometric scale.

    PubMed

    Cobo, Saioa; Molnár, Gábor; Carcenac, Franck; Szilágyi, Petra A; Salmon, Lionel; Vieu, Christophe; Bousseksou, Azzedine

    2010-08-01

    We present a new approach for patterning thin films of Prussian blue at the micro- and nano-metric scales. In a first step, a resist was deposited on a gold surface and patterns were generated by photolithography or electron beam lithography. The Prussian blue with idealized formula of KFe(III)[Fe(II)(CN)6] was deposited through the sequential exposure of the patterned surface to a series of solutions containing alternately absorbable Fe3+ cations and [Fe(CN)6]4- anions. These building blocks are gradually associated into dense and continuous films and patterned structures of Prussian blue can be obtained finally by lift-off. This approach was also used to deposit Prussian blue thin films on interdigitated nanoelectrodes and the current-voltage characteristics of this device were investigated.

  7. Molecular dynamics simulation investigation on the plastic flow behaviour of silicon during nanometric cutting

    NASA Astrophysics Data System (ADS)

    Zare Chavoshi, Saeed; Goel, Saurav; Luo, Xichun

    2016-01-01

    Molecular dynamics (MD) simulation was carried out to acquire an in-depth understanding of the flow behaviour of single crystal silicon during nanometric cutting on three principal crystallographic planes and at different cutting temperatures. The key findings were that (i) the substrate material underneath the cutting tool was observed for the first time to experience a rotational flow akin to fluids at all the tested temperatures up to 1200 K. (ii) The degree of flow in terms of vorticity was found higher on the (1 1 1) crystal plane signifying better machinability on this orientation in accord with the current pool of knowledge (iii) an increase in the machining temperature reduces the spring-back effect and thereby the elastic recovery and (iv) the cutting orientation and the cutting temperature showed significant dependence on the location of the stagnation region in the cutting zone of the substrate.

  8. Spin pumping and Gilbert damping in atomically flat nanometric thick YIG|NM system

    NASA Astrophysics Data System (ADS)

    Alyahyaei, H. M.; Tang, Chi; Yang, Bowen; Shi, Jing

    2014-03-01

    Epitaxial nanometric thick ytrrium iron garnet (YIG) films grown on (111) and (110) gadolliun gallium garnet (GGG) substrates via PLD exhibit an atomically flat surface. This extremely flat surface with a roughness ~ 0.1 Å offers a more controlled study of the physical mechanism behind the newly observed damping in YIG|NM bilayer systems. Our bilayer systems consist of a 30 nm thick YIG film, either (111) or (110), and a non-magnetic layer, either beta-phase Ta or Pd, with thickness ranging from 0 to 20 nm. We have performed ferromagnetic resonance (FMR) experiments and observed systematic thickness dependence of the FMR linewidth. As the thickness of NM increases, the FMR linewidth increases rapidly and then slowly approaches saturation. The effect of the YIG surface on the Gilbert damping due to the magnetic proximity effect and on spin pumping in such bilayer systems will be discussed. The research is supported by NSF/EECS.

  9. Single Phosphorus Ion Implantation into Prefabricated Nanometre Cells of Silicon Devices for Quantum Bit Fabrication

    NASA Astrophysics Data System (ADS)

    Yang, Changyi; Jamieson, David N.; Pakes, Chris; Prawer, Steven; Dzurak, Andrew; Stanley, Fay; Spizziri, Paul; Macks, Linda; Gauja, Eric; Clark, Robert G.

    2003-06-01

    In the near future, devices that employ single atoms to store or manipulate information will be constructed. For example, a solid-state quantum computer has been proposed that encodes information in the nuclear spin of shallow arrays of single 31P atoms (quantum bits or qubits) in a matrix of pure silicon. Construction of these devices presents formidable challenges. One strategy is to use single ion implantation, with the energy range of 10 to 20 keV, to load the qubits into prefabricated cells of the device with a period of a few tens of nanometres. We have developed a method of single ion implantation that employs detector electrodes adjacent to the prefabricated qubit cells that can detect on-line single keV ion strikes appropriate for the fabrication of shallow arrays. Our method of the sub-20 keV single ion detection utilizes a pure silicon substrate with a very high resistivity, a thin (5 nm) SiO2 surface layer, biased electrodes applied to the surface and sensitive electronics that can detect the charge transient from single keV ion strikes. We show that our detectors have a near 100% efficiency for keV ions, extremely thin dead layer thickness (˜5 nm) and a wide sensitive region extending laterally from the electrodes (greater than 15 μm) where the nanometre cells can be constructed. We compare the method with the other methods, such as those of measuring the secondary electrons or phonons induced by single ion impacts.

  10. Three-month performance evaluation of the Nanometrics, Inc., Libra Satellite Seismograph System in the northern California Seismic Network

    USGS Publications Warehouse

    Oppenheimer, David H.

    2000-01-01

    In 1999 the Northern California Seismic Network (NCSN) purchased a Libra satellite seismograph system from Nanometrics, Inc to assess whether this technology was a cost-effective and robust replacement for their analog microwave system. The system was purchased subject to it meeting the requirements, criteria and tests described in Appendix A. In early 2000, Nanometrics began delivery of various components of the system, such as the hub and remote satellite dish and mounting hardware, and the NCSN installed and assembled most equipment in advance of the arrival of Nanometrics engineers to facilitate the configuration of the system. The hub was installed in its permanent location, but for logistical reasons the "remote" satellite hardware was initially configured at the NCSN for testing. During the first week of April Nanometrics engineers came to Menlo Park to configure the system and train NCSN staff. The two dishes were aligned with the satellite, and the system was fully operational in 2 days with little problem. Nanometrics engineers spent the remaining 3 days providing hands-on training to NCSN staff in hardware/software operation, configuration, and maintenance. During the second week of April 2000, NCSN staff moved the entire remote system of digitizers, dish assembly, and mounting hardware to Mammoth Lakes, California. The system was reinstalled at the Mammoth Lakes water treatment plant and communications successfully reestablished with the hub via the satellite on 14 April 2000. The system has been in continuous operation since then. This report reviews the performance of the Libra system for the three-month period 20 April 2000 through 20 July 2000. The purpose of the report is to assess whether the system passed the acceptance tests described in Appendix A. We examine all data gaps reported by NCSN "gap list" software and discuss their cause.

  11. Efficient hypoxic activation of the anticancer agent AQ4N by CYP2S1 and CYP2W1.

    PubMed

    Nishida, Clinton R; Lee, Melody; de Montellano, Paul R Ortiz

    2010-09-01

    AQ4N [1,4-bis{[2-(dimethylamino-N-oxide)ethyl]amino}-5,8-dihydroxyanthracene-9,10-dione], a prodrug with two dimethylamino N-oxide groups, is converted to the topoisomerase II inhibitor AQ4 [1,4-bis{[2-(dimethylamino)ethyl]amino}-5,8-dihydroxy-anthracene-9,10-dione] by reduction of the N-oxides to dimethylamino substituents. Earlier studies showed that several drug-metabolizing cytochrome P450 (P450) enzymes can catalyze this reductive reaction under hypoxic conditions comparable with those in solid tumors. CYP2S1 and CYP2W1, two extrahepatic P450 enzymes identified from the human genome whose functions are unknown, are expressed in hypoxic tumor cells at much higher levels than in normal tissue. Here, we demonstrate that CYP2S1, contrary to a published report (Mol Pharmacol 76:1031-1043, 2009), is efficiently reduced by NADPH-P450 reductase. Most importantly, both CYP2S1 and CYP2W1 are better catalysts for the reductive activation of AQ4N to AQ4 than all previously examined P450 enzymes. The overexpression of CYP2S1 and CYP2W1 in tumor tissues, together with their high catalytic activities for AQ4N activation, suggests that they may be exploited for the localized activation of anticancer prodrugs.

  12. Computational chemical studies on thermochemistry and ring strains in cyclic [n]metaphenyleneacetylenes, butadiyne-bridged [4n]metacyclophynes, and butadiyne-bridged [4n]paracyclophynes.

    PubMed

    Ali, Mohamad Akbar; Krishnan, Mangala Sunder

    2010-09-01

    The thermochemical properties and ring strains in cyclic [n]metaphenyleneacetylenes ([n]CMPAs), butadiyne-bridged [4(n)]metacyclophynes (B-B[4(n)]MCs), and butadiyne-bridged [4(n)]paracyclophynes (B-B[4(n)]PCs) were studied using a homodesmotic reaction scheme coupled with density functional theory (B3LYP/6-31G*, mPW1PW91/6-31G*, and M06-2X/6-31+G**//B3LYP/6-31G*). Strain energies of [n]CMPAs and B-B[4(n)]MCs decrease first from very high values for small rings to become zero when n becomes 6, then increase with n, and finally decrease as n becomes larger than 8. In the case of B-B[4(n)]PCs, strain energies decrease with increasing n. Heats of formation of [n]CMPAs, B-B[4(n)]MCs, and B-B[4(n)]PCs increase steadily with increasing numbers of phenylacetylene and 1-(buta-1,3-diynyl)benzene to reach a near-constant value per unit monomer as n increases. The geometries and (vibrational and nuclear magnetic resonance) spectroscopic properties of [n]CMPAs, B-B[4(n)]MCs, and B-B[4(n)]PCs were also studied. Geometrical parameters, Raman frequencies, and (1)H NMR chemical shifts of [3]CMPA and [4]CMPA are found to be in good agreement with compounds for which there are experimentally available values at the B3LYP/6-31G* level of theory. In addition, electronic structure calculations were carried out for [n]CMPAs, B-B[4(n)]MCs, and B-B[4(n)]PCs. Ring diameters were also calculated for B-B[4(n)]PCs. PMID:20695635

  13. SU-E-CAMPUS-I-01: Nanometric Organic Photovoltaic Thin Film X-Ray Detectors for Clinical KVp Beams

    SciTech Connect

    Elshahat, Bassem; Gill, Hardeep; Kumar, Jayant; Sajo, Erno; Filipyev, Ilya; Zygmanski, Piotr; Shrestha, Suman; Hesser, Jurgen; Karellas, Andrew

    2014-06-15

    Purpose: To fabricate and test nanometric organic photovoltaic (OPV) cells made of various active-layer/electrode thicknesses and sizes; to determine the optimal material combinations and geometries suitable for dose measurements in clinical kilovoltage x-ray beams. Methods: The OPV consisted of P3HT:PCBM photoactive materials sandwiched between aluminum and Indium Tin Oxide (ITO) electrodes. Direct conversion of xrays in the active layer composed of donor and acceptor semiconducting organic materials generated signal in photovoltaic mode (without external voltage bias). OPV cells were fabricated with different active layer thicknesses (150, 270, 370 nm) and electrode areas (0.4, 0.7, 0.9, 1.4, 2.6 cm{sup 2}). A series of experiments were preformed in the energy range of 60–150 kVp. The net current per unit area (nA/cm{sup 2}) was measured using 200 mAs time-integrated beam current. Results: The net OPV current as function of beam energy (kVp) was proportional to ∼E{sup 0,4} {sup 5} when adjusted for beam output. The best combination of parameters for these cells was 270 nm active layer thicknesses for 0.7 cm{sup 2} electrode area. The measured current ranged from 0.69 to 2.43 nA/cm{sup 2} as a function of x-ray energy between 60 and 150 kVp, corresponding to 0.09 – 0.06 nA/cm{sup 2}/mGy, respectively, when adjusted for the beam output. Conclusion: The experiments indicate that OPV detectors possessing 270 nm active layer and 0.7 cm{sup 2} Al electrode areas have sensitivity by a factor of 2.5 greater than commercial aSi thin film PV. Because OPV can be made flexible and they do not require highvoltage bias supply, they open the possibility for using as in-vivo detectors in radiation safety in x-ray imaging beams.

  14. Specific features of structure and properties of solutions, melts and solid states of polymers in confined nanometric volumes

    NASA Astrophysics Data System (ADS)

    Volynskii, A. L.; Yarysheva, A. Yu; Rukhlya, E. G.; Yarysheva, L. M.; Bakeev, N. F.

    2014-11-01

    The data on the influence of spatial restrictions on the structure and properties of polymers are analyzed. It is demonstrated that dispersion of polymers into aggregates of nanometre size critically changes all their characteristics in consequence of conformational restructuring of the polymeric chains. The spatial restrictions affect both characteristics of phase transitions in polymers (the crystallization and melting points, heat of melting and the degree of crystallinity decrease) and the processes of orientation of crystallites in asymmetric volumes of nanometre size. It is shown that these effects are primarily related to the changes in relative contribution of the stages of nucleation and growth of crystallite to the overall process occurring in confined volumes. Comparative analysis of the effects of spatial restrictions on the processes of crystallization of polymers and low-molecular-mass compounds is carried out. The similarity in changes in thermodynamic characteristics for both series of compounds is revealed. The bibliography includes 211 references.

  15. Immunological properties of Andean starch films are independent of their nanometric roughness and stiffness.

    PubMed

    Torres, F G; Troncoso, O P; Gamucci, O; Corvaglia, S; Brunetti, V; Bardi, G

    2015-04-01

    Starch is a natural material extracted from roots, seeds, stems and tubers of different plants. It can be processed as a thermoplastic to produce a variety promising products for biomedical applications, including foams, sheets and films. In the present work, we investigated the immunological properties of microfilms prepared with starches extracted from six different types of Andean potatoes and their relationship with the different film-surface features. We confirmed the biocompatibility of all the films using THP-1 human monocytes, noticing only slight decrease in cell viability in two of the tested starches. We also analyzed pro-inflammatory cytokine release and immune cell surface receptor modulation on THP-1 plated onto the films. Our data show differences in the immunological profile of the same cells cultured onto the different starch films. Furthermore, we examined whether the dissimilar stiffness or the nanometric roughness of the films might influence the immune stimulation of the THP-1 monocytes. Our results demonstrate no correlation between cultured THP-1 immune activation and surface film characteristics. We conclude that different Andean native potato starch films have specific ability to interact with cell membranes of immune cells, conceivably due to the different spatial localization of amylose and amylopectin in the diverse starches.

  16. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis

    PubMed Central

    Córdoba, Ainara López; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R. Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V.; Korchev, Yuri

    2016-01-01

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

  17. A model for ultrasound absorption and dispersion in dilute suspensions of nanometric contrast agents.

    PubMed

    Coulouvrat, François; Thomas, Jean-Louis; Astafyeva, Ksenia; Taulier, Nicolas; Conoir, Jean-Marc; Urbach, Wladimir

    2012-12-01

    Ultrasound dispersion and absorption are examined in dilute suspensions of contrast agents of nanometric size, with a typical radius around 100 nm. These kinds of contrast agents are designed for targeted delivery of drugs for cancer treatment. Compared to standard contrast agents used for imaging, particles are of smaller size to pass through the endothelial barrier, their shell, made up of biocompatible polymer, is stiffer to undergo a longer lifetime, and they have a liquid core instead of a gaseous one. Ultrasound propagation in dilute suspension is modeled by combining two modes for particle oscillations. The first one is a dilatational mode assuming an incompressible shell with a rheological behavior of Kelvin-Voigt or Maxwell type. The second one is a translational mode induced by visco-inertial interaction with the ambient fluid. The relative importance of these two modes of interaction on both dispersion and absorption is quantified and analyzed for a model system and for two radii (75 and 150 nm) and the two rheological models. The influence of shell parameters (Young modulus, viscosity, and relative thickness) is finally discussed.

  18. Alignment hierarchies: engineering architecture from the nanometre to the micrometre scale

    PubMed Central

    Kureshi, Alvena; Cheema, Umber; Alekseeva, Tijna; Cambrey, Alison; Brown, Robert

    2010-01-01

    Natural tissues are built of metabolites, soluble proteins and solid extracellular matrix components (largely fibrils) together with cells. These are configured in highly organized hierarchies of structure across length scales from nanometre to millimetre, with alignments that are dominated by anisotropies in their fibrillar matrix. If we are to successfully engineer tissues, these hierarchies need to be mimicked with an understanding of the interaction between them. In particular, the movement of different elements of the tissue (e.g. molecules, cells and bulk fluids) is controlled by matrix structures at distinct scales. We present three novel systems to introduce alignment of collagen fibrils, cells and growth factor gradients within a three-dimensional collagen scaffold using fluid flow, embossing and layering of construct. Importantly, these can be seen as different parts of the same hierarchy of three-dimensional structure, as they are all formed into dense collagen gels. Fluid flow aligns collagen fibrils at the nanoscale, embossed topographical features provide alignment cues at the microscale and introducing layered configuration to three-dimensional collagen scaffolds provides microscale- and mesoscale-aligned pathways for protein factor delivery as well as barriers to confine protein diffusion to specific spatial directions. These seemingly separate methods can be employed to increase complexity of simple extracellular matrix scaffolds, providing insight into new approaches to directly fabricate complex physical and chemical cues at different hierarchical scales, similar to those in natural tissues. PMID:20926429

  19. Nanometre-scale probing of spin waves using single-electron spins

    PubMed Central

    van der Sar, Toeno; Casola, Francesco; Walsworth, Ronald; Yacoby, Amir

    2015-01-01

    Pushing the frontiers of condensed-matter magnetism requires the development of tools that provide real-space, few-nanometre-scale probing of correlated-electron magnetic excitations under ambient conditions. Here we present a practical approach to meet this challenge, using magnetometry based on single nitrogen-vacancy centres in diamond. We focus on spin-wave excitations in a ferromagnetic microdisc, and demonstrate local, quantitative and phase-sensitive detection of the spin-wave magnetic field at ∼50 nm from the disc. We map the magnetic-field dependence of spin-wave excitations by detecting the associated local reduction in the disc's longitudinal magnetization. In addition, we characterize the spin–noise spectrum by nitrogen-vacancy spin relaxometry, finding excellent agreement with a general analytical description of the stray fields produced by spin–spin correlations in a 2D magnetic system. These complementary measurement modalities pave the way towards imaging the local excitations of systems such as ferromagnets and antiferromagnets, skyrmions, atomically assembled quantum magnets, and spin ice. PMID:26249673

  20. Top-down fabrication of sub-nanometre semiconducting nanoribbons derived from molybdenum disulfide sheets.

    PubMed

    Liu, Xiaofei; Xu, Tao; Wu, Xing; Zhang, Zhuhua; Yu, Jin; Qiu, Hao; Hong, Jin-Hua; Jin, Chuan-Hong; Li, Ji-Xue; Wang, Xin-Ran; Sun, Li-Tao; Guo, Wanlin

    2013-01-01

    Developments in semiconductor technology are propelling the dimensions of devices down to 10 nm, but facing great challenges in manufacture at the sub-10 nm scale. Nanotechnology can fabricate nanoribbons from two-dimensional atomic crystals, such as graphene, with widths below the 10 nm threshold, but their geometries and properties have been hard to control at this scale. Here we find that robust ultrafine molybdenum-sulfide ribbons with a uniform width of 0.35 nm can be widely formed between holes created in a MoS2 sheet under electron irradiation. In situ high-resolution transmission electron microscope characterization, combined with first-principles calculations, identifies the sub-1 nm ribbon as a Mo5S4 crystal derived from MoS2, through a spontaneous phase transition. Further first-principles investigations show that the Mo5S4 ribbon has a band gap of 0.77 eV, a Young's modulus of 300GPa and can demonstrate 9% tensile strain before fracture. The results show a novel top-down route for controllable fabrication of functional building blocks for sub-nanometre electronics.

  1. X-ray reflectivity theory for determining the density profile of a liquid under nanometre confinement.

    PubMed

    Perret, Edith; Nygård, Kim; Satapathy, Dillip K; Balmer, Tobias E; Bunk, Oliver; Heuberger, Manfred; van der Veen, J Friso

    2010-07-01

    An X-ray reflectivity theory on the determination of the density profile of a molecular liquid under nanometre confinement is presented. The confinement geometry acts like an X-ray interferometer, which consists of two opposing atomically flat single-crystal mica membranes with an intervening thin liquid film of variable thickness. The X-rays reflected from the parallel crystal planes (of known structure) and the layered liquid in between them (of unknown structure) interfere with one another, making X-ray reflectivity highly sensitive to the liquid's density profile along the confinement direction. An expression for the reflected intensity as a function of momentum transfer is given. The total structure factor intensity for the liquid-filled confinement device is derived as a sum of contributions from the inner and outer crystal terminations. The method presented readily distinguishes the confined liquid from the liquid adsorbed on the outer mica surfaces. It is illustrated for the molecular liquid tetrakis(trimethyl)siloxysilane, confined by two mica surfaces at a distance of 8.6 nm.

  2. Auxetic tissue engineering scaffolds with nanometric features and resonances in the megahertz range

    NASA Astrophysics Data System (ADS)

    Díaz Lantada, Andrés; Muslija, Alban; Predestinación García-Ruíz, Josefa

    2015-05-01

    In this study we present an improved approach for the development of auxetics based on the use of deep reactive ion etching (DRIE) after a high-precision mask fabrication procedure. The whole process stands out for its precision (reaching nanometric detail), for the high aspect ratio (AR) attainable and for the possibility of promoting mass production. The quality of the proposed strategy is verified by the manufacture of an auxetic cantilever and bridged structures using two common planar auxetic geometries. The present process significantly increases the precision and AR of the micro-auxetics obtained when compared to state-of-the-art micromachining procedures and solves common challenges linked to structure adhesion to the substrate. The potential of the manufactured structures for the development of resonant structures is analyzed by means of finite-element-method- (FEM) based simulations, showing resonances in the megahertz range. A final application example, linked to monitoring cell culture processes upon auxetic scaffolds, is also proposed and analyzed by computational procedures. The initial cell culture results are also included and help to validate the scaffolds obtained and the materials used for future tissue engineering studies.

  3. Effect of Nanometric Lactobacillus plantarum in Kimchi on Dextran Sulfate Sodium-Induced Colitis in Mice.

    PubMed

    Lee, Hyun Ah; Bong, Yeon-Ju; Kim, Hyunung; Jeong, Ji-Kang; Kim, Hee-Young; Lee, Kwang-Won; Park, Kun-Young

    2015-10-01

    Nanometric Lactobacillus plantarum (nLp) is a processed form of Lab. plantarum derived from kimchi and is 0.5-1.0 μm in size. This study was undertaken to determine the effect of nLp and kimchi plus nLp (K-nLp) on a dextran sulfate sodium (DSS)-induced mouse model of colitis. Animals fed nLp or K-nLp had longer colons, but lower colon weights per unit length than DSS controls. In addition, nLp- or K-nLp-fed animals showed lower levels of proinflammatory cytokines and inflammatory genes in serum and in colon tissues, lower populations of total bacteria, but higher populations of lactic acid bacteria in feces, and lower activities of fecal β-glucosidase and β-glucuronidase. Furthermore, these suppressive activities of nLp on colitis were equivalent to or higher than those of naive Lab. plantarum. Consequently, nLp was found to exhibit anticolitic effects, and the addition of nLp to kimchi was found to enhance the protective activity of kimchi against DSS-induced colitis. These results suggest that nLp might be an effective substitute for live probiotics and be useful as a functional ingredient with the anticolitic activity by the probiotic and food processing industries.

  4. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis.

    PubMed

    Zhang, Yanjun; Clausmeyer, Jan; Babakinejad, Babak; López Córdoba, Ainara; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V; Korchev, Yuri

    2016-03-22

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements.

  5. Top-down fabrication of sub-nanometre semiconducting nanoribbons derived from molybdenum disulfide sheets.

    PubMed

    Liu, Xiaofei; Xu, Tao; Wu, Xing; Zhang, Zhuhua; Yu, Jin; Qiu, Hao; Hong, Jin-Hua; Jin, Chuan-Hong; Li, Ji-Xue; Wang, Xin-Ran; Sun, Li-Tao; Guo, Wanlin

    2013-01-01

    Developments in semiconductor technology are propelling the dimensions of devices down to 10 nm, but facing great challenges in manufacture at the sub-10 nm scale. Nanotechnology can fabricate nanoribbons from two-dimensional atomic crystals, such as graphene, with widths below the 10 nm threshold, but their geometries and properties have been hard to control at this scale. Here we find that robust ultrafine molybdenum-sulfide ribbons with a uniform width of 0.35 nm can be widely formed between holes created in a MoS2 sheet under electron irradiation. In situ high-resolution transmission electron microscope characterization, combined with first-principles calculations, identifies the sub-1 nm ribbon as a Mo5S4 crystal derived from MoS2, through a spontaneous phase transition. Further first-principles investigations show that the Mo5S4 ribbon has a band gap of 0.77 eV, a Young's modulus of 300GPa and can demonstrate 9% tensile strain before fracture. The results show a novel top-down route for controllable fabrication of functional building blocks for sub-nanometre electronics. PMID:23653188

  6. Spearhead Nanometric Field-Effect Transistor Sensors for Single-Cell Analysis.

    PubMed

    Zhang, Yanjun; Clausmeyer, Jan; Babakinejad, Babak; López Córdoba, Ainara; Ali, Tayyibah; Shevchuk, Andrew; Takahashi, Yasufumi; Novak, Pavel; Edwards, Christopher; Lab, Max; Gopal, Sahana; Chiappini, Ciro; Anand, Uma; Magnani, Luca; Coombes, R Charles; Gorelik, Julia; Matsue, Tomokazu; Schuhmann, Wolfgang; Klenerman, David; Sviderskaya, Elena V; Korchev, Yuri

    2016-03-22

    Nanometric field-effect-transistor (FET) sensors are made on the tip of spear-shaped dual carbon nanoelectrodes derived from carbon deposition inside double-barrel nanopipettes. The easy fabrication route allows deposition of semiconductors or conducting polymers to comprise the transistor channel. A channel from electrodeposited poly pyrrole (PPy) exhibits high sensitivity toward pH changes. This property is exploited by immobilizing hexokinase on PPy nano-FETs to give rise to a selective ATP biosensor. Extracellular pH and ATP gradients are key biochemical constituents in the microenvironment of living cells; we monitor their real-time changes in relation to cancer cells and cardiomyocytes. The highly localized detection is possible because of the high aspect ratio and the spear-like design of the nano-FET probes. The accurately positioned nano-FET sensors can detect concentration gradients in three-dimensional space, identify biochemical properties of a single living cell, and after cell membrane penetration perform intracellular measurements. PMID:26816294

  7. Live-cell protein labelling with nanometre precision by cell squeezing

    PubMed Central

    Kollmannsperger, Alina; Sharei, Armon; Raulf, Anika; Heilemann, Mike; Langer, Robert; Jensen, Klavs F.; Wieneke, Ralph; Tampé, Robert

    2016-01-01

    Live-cell labelling techniques to visualize proteins with minimal disturbance are important; however, the currently available methods are limited in their labelling efficiency, specificity and cell permeability. We describe high-throughput protein labelling facilitated by minimalistic probes delivered to mammalian cells by microfluidic cell squeezing. High-affinity and target-specific tracing of proteins in various subcellular compartments is demonstrated, culminating in photoinduced labelling within live cells. Both the fine-tuned delivery of subnanomolar concentrations and the minimal size of the probe allow for live-cell super-resolution imaging with very low background and nanometre precision. This method is fast in probe delivery (∼1,000,000 cells per second), versatile across cell types and can be readily transferred to a multitude of proteins. Moreover, the technique succeeds in combination with well-established methods to gain multiplexed labelling and has demonstrated potential to precisely trace target proteins, in live mammalian cells, by super-resolution microscopy. PMID:26822409

  8. Imaging nanometre-scale structure in cells using in situ aberration correction.

    PubMed

    Fuller, C J; Straight, A F

    2012-10-01

    Accurate distance measurements of cellular structures on a length scale relevant to single macromolecules or macromolecular complexes present a major challenge for biological microscopy. In addition to the inherent challenges of overcoming the limits imposed by the diffraction of light, cells themselves are a complex and poorly understood optical environment. We present an extension of the high-resolution colocalization method to measure three dimensional distances between diffraction-limited objects using standard widefield fluorescence microscopy. We use this method to demonstrate that in three dimensions, cells intrinsically introduce a large and variable amount of chromatic aberration into optical measurements. We present a means of correcting this aberration in situ [termed 'Colocalization and In-situ Correction of Aberration for Distance Analysis' (CICADA)] by exploiting the fact that there is a linear relationship between the degree of aberration between different wavelengths. By labelling a cellular structure with redundantly multi-colour labelled antibodies, we can create an intracellular fiducial marker for correcting the individual aberrations between two different wavelengths in the same cells. Our observations demonstrate that with suitable corrections, nanometre scale three-dimensional distance measurements can be used to probe the substructure of macromolecular complexes within cells.

  9. Single Nanometric Memory Unit Based On a Protein-Nanoparticle Hybrid

    NASA Astrophysics Data System (ADS)

    Medalsy, Izhar; Heyman, Arnon; Shoseyov, Oded; Porath, Danny

    2009-03-01

    Proteins as an isolating template and nanoparticle (NP) as an electric storage component can form a single addressable unit cell isolated from the conductive surface and adjacent NPs. This setup gives rise to a wide range of nanoelectronic applications. Here we demonstrate, by Conductive AFM, a single nanometric memory unit using individual protein-NP hybrids. SP1 is a boiling-stable ring-shaped protein, 11 nm in diameter. Mutants of SP1 were synthesized allowing its selective attachment to gold surface and the formation of 2D arrays using methods such as phospholipids trough and Langmuir Blodgett. The SP1 inner pore was connected to Si NP forming a chargeable entity embedded in an isolating unit over a conductive surface. Each NP holds three charging states: natural, positive and negative. The charging life times are 10 min in ambient and days in vacuum. Using this setup, and the relative long charging time, we were able to apply a read and write operations on individual 5nm Si NP embedded in a stable protein.

  10. Alignment hierarchies: engineering architecture from the nanometre to the micrometre scale.

    PubMed

    Kureshi, Alvena; Cheema, Umber; Alekseeva, Tijna; Cambrey, Alison; Brown, Robert

    2010-12-01

    Natural tissues are built of metabolites, soluble proteins and solid extracellular matrix components (largely fibrils) together with cells. These are configured in highly organized hierarchies of structure across length scales from nanometre to millimetre, with alignments that are dominated by anisotropies in their fibrillar matrix. If we are to successfully engineer tissues, these hierarchies need to be mimicked with an understanding of the interaction between them. In particular, the movement of different elements of the tissue (e.g. molecules, cells and bulk fluids) is controlled by matrix structures at distinct scales. We present three novel systems to introduce alignment of collagen fibrils, cells and growth factor gradients within a three-dimensional collagen scaffold using fluid flow, embossing and layering of construct. Importantly, these can be seen as different parts of the same hierarchy of three-dimensional structure, as they are all formed into dense collagen gels. Fluid flow aligns collagen fibrils at the nanoscale, embossed topographical features provide alignment cues at the microscale and introducing layered configuration to three-dimensional collagen scaffolds provides microscale- and mesoscale-aligned pathways for protein factor delivery as well as barriers to confine protein diffusion to specific spatial directions. These seemingly separate methods can be employed to increase complexity of simple extracellular matrix scaffolds, providing insight into new approaches to directly fabricate complex physical and chemical cues at different hierarchical scales, similar to those in natural tissues.

  11. Electrical and electroluminescent characterization of nanometric multilayers of SiOX/SiOY obtained by LPCVD including non-normal emission

    NASA Astrophysics Data System (ADS)

    Alarcón-Salazar, J.; Zaldívar-Huerta, I. E.; Aceves-Mijares, M.

    2016-06-01

    This work describes the analysis and fabrication by Low Pressure Chemical Vapor Deposition of two light-emitting capacitors (LECs) constituted by nanometric multilayers of silicon-rich oxide. For both structures, seven layers were used: three light emitting layers with 6% silicon excess and four conductive layers with 12% silicon excess for one LEC and the other with 14% silicon excess. Both LECs were annealed at 1100 °C. Both multilayers demonstrate a substantially improved photoluminescent response compared to single emitting layers. A dielectric constant of 4.1 and a trap density of 1016 cm-3 were obtained from capacitance-voltage curves. Analysis of current-voltage and electroluminescence-voltage (EL-V) characteristics indicates that EL initiates under the space-charge-limited current mechanism, and the required voltage to turn on the emission is 38 V which is the trap-free limit voltage. However, EL increases exponentially under the impact ionization and trap-assisted tunneling conduction mechanisms. The electroluminescence spectra for both multilayers show two emission peaks centered in 450 and 700 nm attributed to oxygen defects. Also, the LEC non-normal emission was measured and it behaves like a Lambertian optical source. Both multilayers obtain the values of efficiency in the order of 10-6 which is in good agreement with the values reported in the literature.

  12. Diffraction pattern by nanometric thin films under illumination of an orbital angular momentum beam with integer topological charge

    NASA Astrophysics Data System (ADS)

    Mendoza, J. H.; Díaz, C. F.; Acevedo, C. H.; Torres, Y.

    2016-02-01

    The orbital angular momentum of light has a big contribution in many engineering applications like optical communications, because this physical property allows eigenstates characteristic of the wavefront rotation when the beam is propagated. The nature of these eigenstates allows that information can be encoded and gives immunity to electromagnetic interference, allowing an increase of bandwidth, cadence and capacity of the communication channel. This work shown the methodology using nanometric thin films like Titanium based (TiO2) grown over strontium titanate (SrTiO3) support, to distinguish and discriminate a well- defined integer value of the topological charge of an OAM beam.

  13. Size-dependent permittivity and intrinsic optical anisotropy of nanometric gold thin films: a density functional theory study.

    PubMed

    Laref, Slimane; Cao, Jiangrong; Asaduzzaman, Abu; Runge, Keith; Deymier, Pierre; Ziolkowski, Richard W; Miyawaki, Mamoru; Muralidharan, Krishna

    2013-05-20

    Physical properties of materials are known to be different from the bulk at the nanometer scale. In this context, the dependence of optical properties of nanometric gold thin films with respect to film thickness is studied using density functional theory (DFT). We find that the in-plane plasma frequency of the gold thin film decreases with decreasing thickness and that the optical permittivity tensor is highly anisotropic as well as thickness dependent. Quantitative knowledge of planar metal film permittivity's thickness dependence can improve the accuracy and reliability of the designs of plasmonic devices and electromagnetic metamaterials. The strong anisotropy observed may become an alternative method of realizing indefinite media.

  14. Purification and characterization of 4-N-trimethylamino-1-butanol dehydrogenase from Fusarium merismoides var. acetilereum.

    PubMed

    Fujimitsu, Hiroshi; Taniyama, Yuko; Tajima, Sae; Mohamed Ahmed, Isam A; Arima, Jiro; Mori, Nobuhiro

    2016-09-01

    From investigation of 60 filamentous fungi, we identified Fusarium merismoides var. acetilereum, which uses 4-N-trimethylamino-1-butanol (TMA-butanol) as the sole source of carbon and nitrogen. The fungus produced NAD(+)-dependent TMA-butanol dehydrogenase (DH) when it was cultivated in medium containing TMA-butanol. The enzyme showed molecular mass of 40 kDa by SDS-PAGE and 160 kDa by gel filtration, suggesting that it is a homotetramer. TMA-butanol DH is stable at pH 7.5-9.0. It exhibits moderate stability with respect to temperature (up to 30 °C). Additionally, it has optimum activity at 45 °C and at pH 9.5. The enzyme has broad specificity to various alkyl alcohols and amino alkyl alcohols, and the carbon chains of which are longer than butanol. Moreover, the activity is strongly inhibited by oxidizing agents, carbonyl and thiol modulators, and chelating agents. This report is the first study examining TMA-butanol DH from eukaryotic microbes. PMID:27121905

  15. A nanometre-scale resolution interference-based probe of interfacial phenomena between microscopic objects and surfaces

    PubMed Central

    Contreras-Naranjo, Jose C.; Ugaz, Victor M.

    2013-01-01

    Interferometric techniques have proven useful to infer proximity and local surface profiles of microscopic objects near surfaces. But a critical trade-off emerges between accuracy and mathematical complexity when these methods are applied outside the vicinity of closest approach. Here we introduce a significant advancement that enables reflection interference contrast microscopy to provide nearly instantaneous reconstruction of an arbitrary convex object’s contour next to a bounding surface with nanometre resolution, making it possible to interrogate microparticle/surface interaction phenomena at radii of curvature 1,000 times smaller than those accessible by the conventional surface force apparatus. The unique view-from-below perspective of reflection interference contrast microscopy also reveals previously unseen deformations and allows the first direct observation of femtolitre-scale capillary condensation dynamics underneath micron-sized particles. Our implementation of reflection interference contrast microscopy provides a generally applicable nanometre-scale resolution tool that can be potentially exploited to dynamically probe ensembles of objects near surfaces so that statistical/probabilistic behaviour can be realistically captured. PMID:23715278

  16. Finishing of AT-cut quartz crystal wafer with nanometric thickness uniformity by pulse-modulated atmospheric pressure plasma etching.

    PubMed

    Yamamura, Kazuya; Ueda, Masaki; Shibahara, Masafumi; Zettsu, Nobuyuki

    2011-04-01

    Quartz resonator is a very important device to generate a clock frequency for information and telecommunication system. Improvement of the productivity of the quartz resonator is always required because a huge amount of the resonator is demanded for installing to various electronic devices. Resonance frequency of the quartz resonator is decided by the thickness of the quartz crystal wafer. Therefore, it is necessary to uniform the thickness distribution of the wafer with nanometric level. We have proposed the improvement technique of the thickness distribution of the quartz crystal wafer by numerically controlled correction using atmospheric pressure plasma which is non-contact and chemical removal technique. Heating effects of the quartz wafer in the removal rate and the correction accuracy were investigated. The heating of the substrate and compensate of the scanning speed of the worktable according to the variation of the surface temperature enabled an increase of 50% in the etching rate and 10-nanometric-level accuracy in the correction of the thickness distribution of the quartz wafer, respectively.

  17. Constructing optimal entanglement witnesses. II. Witnessing entanglement in 4N×4N systems

    NASA Astrophysics Data System (ADS)

    Chruściński, Dariusz; Pytel, Justyna

    2010-11-01

    We provide a class of optimal nondecomposable entanglement witnesses for 4N×4N composite quantum systems or, equivalently, another construction of nondecomposable positive maps in the algebra of 4N×4N complex matrices. This construction provides natural generalization of the Robertson map. It is shown that their structural physical approximations give rise to entanglement breaking channels.

  18. Constructing optimal entanglement witnesses. II. Witnessing entanglement in 4Nx4N systems

    SciTech Connect

    Chruscinski, Dariusz; Pytel, Justyna

    2010-11-15

    We provide a class of optimal nondecomposable entanglement witnesses for 4Nx4N composite quantum systems or, equivalently, another construction of nondecomposable positive maps in the algebra of 4Nx4N complex matrices. This construction provides natural generalization of the Robertson map. It is shown that their structural physical approximations give rise to entanglement breaking channels.

  19. [Effect of humic acids on migration and transformation of NH4(+) -N in saturated aquifer].

    PubMed

    Meng, Qing-Jun; Zhang, Yan; Feng, Qi-Yan; Zhang, Shuang-Sheng

    2011-11-01

    Isothermal adsorption experiment was used to study the adsorbing process of NH4(+) -N in quartz sands under the conditions with and without humic acid; the Langmuir and Freundlich equations were used to fit the absorption result and the maximum adsorption capacity of NH4(+) -N by quarts sands was calculated. Through the soil column experiments, the concentration of NH4(+) -N, NO3(-) -N and NO2(-) -N in effluent water in the tested soil column was investigated, and the effect of humic acid on migration and transformation of NH4(+) -N in saturated aquifer was analyzed, and Pseudo-second-order Kinetics Equation and Two-step Adsorption Kinetics Rate Equation were applied to fit the kinetic processes. The results showed that both Langmuir and Freundlich models can well describe the isothermal adsorption process of NH4(+) -N on the surface of quartz sands, which means that NH4(+) -N adsorbed by the quartz sand was mainly in the form of monolayer adsorption. The humic acid could increase the adsorption capacity of NH4(+) -N on quartz sand, and the saturated adsorption capacity was 0.354 mg x g(-1) under the condition with humic acid and 0.205 mg x g(-1) with the absence of humic acid. The experiment indicated that humic acid increased the adsorption capacity of NH4(+) -N on the surface of quartz sand by increasing adsorption space in the initial stage. After saturation, humic acid influenced the migration and transformation of NH4(+) -N to NO3(-) -N and NO2(-) -N probably through providing carbon source and energy for microorganisms such as nitrifying bacteria and then resulting in lower NH4(+) -N concentration in effluent water. Both Pseudo-second-order Kinetics Equation and Two-step Adsorption Kinetics Rate Equations can well describe the process of NH4(+) -N adsorption kinetics on quartz sand (R2 = 0.997 7 and R2 = 0.998 1 with humic acid; R2 = 0.992 3 and R2 = 0.994 4 without humic acid), indicating that this process was chemical adsorption. By comparing the

  20. Synthesis of two-dimensional titanium nitride Ti4N3 (MXene)

    NASA Astrophysics Data System (ADS)

    Urbankowski, Patrick; Anasori, Babak; Makaryan, Taron; Er, Dequan; Kota, Sankalp; Walsh, Patrick L.; Zhao, Mengqiang; Shenoy, Vivek B.; Barsoum, Michel W.; Gogotsi, Yury

    2016-06-01

    We report on the synthesis of the first two-dimensional transition metal nitride, Ti4N3-based MXene. In contrast to the previously reported MXene synthesis methods - in which selective etching of a MAX phase precursor occurred in aqueous acidic solutions - here a molten fluoride salt is used to etch Al from a Ti4AlN3 powder precursor at 550 °C under an argon atmosphere. We further delaminated the resulting MXene to produce few-layered nanosheets and monolayers of Ti4N3Tx, where T is a surface termination (F, O, or OH). Density functional theory calculations of bare, non-terminated Ti4N3 and terminated Ti4N3Tx were performed to determine the most energetically stable form of this MXene. Bare and functionalized Ti4N3 are predicted to be metallic. Bare Ti4N3 is expected to show magnetism, which is significantly reduced in the presence of functional groups.We report on the synthesis of the first two-dimensional transition metal nitride, Ti4N3-based MXene. In contrast to the previously reported MXene synthesis methods - in which selective etching of a MAX phase precursor occurred in aqueous acidic solutions - here a molten fluoride salt is used to etch Al from a Ti4AlN3 powder precursor at 550 °C under an argon atmosphere. We further delaminated the resulting MXene to produce few-layered nanosheets and monolayers of Ti4N3Tx, where T is a surface termination (F, O, or OH). Density functional theory calculations of bare, non-terminated Ti4N3 and terminated Ti4N3Tx were performed to determine the most energetically stable form of this MXene. Bare and functionalized Ti4N3 are predicted to be metallic. Bare Ti4N3 is expected to show magnetism, which is significantly reduced in the presence of functional groups. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02253g

  1. Determination of 2-ethylhexyl 4-(N-methyl-N-nitrosamino) benzoate in commercial sunscreens and cosmetic products.

    PubMed

    Chou, H J; Yates, R L; Havery, D C; Wenninger, J A

    1995-01-01

    An analytical method has been developed for determination of 2-ethylhexyl 4-(N-methyl-N-nitrosamino) benzoate (NMPABAO), a nitrosamine contaminant in sunscreen products containing 2-ethylhexyl 4-(N,N-dimethylamino) benzoate (Padimate O). The method involves extraction of NMPABAO by column chromatography followed by liquid chromatographic separation and analysis wit a nitric oxide detector. To confirm the presence of NMPABAO in sunscreen products, the N-nitrosamine was synthesized and its structure was determined by infrared spectrophotometry, nuclear magnetic resonance spectrometry, and mass spectrometry (MS). For method validation, recovery studies were performed on a commercial suntan lotion, cream, and gel. Recoveries of NMPABAO added to representative test samples averaged 83%. The method has an estimated detection limit of 30 ppb. The method was used to analyze 25 commercial cosmetic and sunscreen products containing Padimate O. Eleven products contained NMPABAO at levels ranging from 160 to 21000 ppb. NMPABAO presence in 4 products was confirmed by MS at levels > or = 4000 ppb. The highest levels of NMPABAO were associated with products that contained the nitrite-releasing preservative 2-bromo-2-nitro-1,3-propanediol.

  2. Deceleration of single-stranded DNA passing through a nanopore using a nanometre-sized bead structure

    PubMed Central

    Goto, Yusuke; Haga, Takanobu; Yanagi, Itaru; Yokoi, Takahide; Takeda, Ken-ichi

    2015-01-01

    DNA sequencing with a solid-state nanopore requires a reduction of the translocation speeds of single-stranded DNA (ssDNA) over 10 μs/base. In this study, we report that a nanometre-sized bead structure constructed around a nanopore can reduce the moving speed of ssDNA to 270 μs/base by adjusting the diameter of the bead and its surface chemical group. This decelerating effect originates from the strong interaction between ssDNA and the chemical group on the surface of the bead. This nanostructure was simply prepared by dip coating in which a substrate with a nanopore was immersed in a silica bead solution and then dried in an oven. As compared with conventional approaches, our novel method is less laborious, simpler to perform and more effective in reducing ssDNA translocation speed. PMID:26559466

  3. Subnanoradian X-ray phase-contrast imaging using a far-field interferometer of nanometric phase gratings

    PubMed Central

    Wen, Han; Gomella, Andrew A.; Patel, Ajay; Lynch, Susanna K.; Morgan, Nicole Y.; Anderson, Stasia A.; Bennett, Eric E.; Xiao, Xianghui; Liu, Chian; Wolfe, Douglas E.

    2013-01-01

    Hard X-ray phase-contrast imaging characterizes the electron density distribution in an object without the need for radiation absorption. The power of phase contrast to resolve subtle changes, such as those in soft tissue structures, lies in its ability to detect minute refractive bending of X-rays. Here we report a far-field, two-arm interferometer based on the new nanometric phase gratings, which can detect X-ray refraction with subnanoradian sensitivity, and at the same time overcomes the fundamental limitation of ultra-narrow bandwidths (Δλ/λ~10−4) of the current, most sensitive methods based on crystal interferometers. On a 1.5% bandwidth synchrotron source, we demonstrate clear visualization of blood vessels in unstained mouse organs in simple projection views, with over an order-of-magnitude higher phase contrast than current near-field grating interferometers. PMID:24189696

  4. Sub-nanometre resolution imaging of polymer–fullerene photovoltaic blends using energy-filtered scanning electron microscopy

    PubMed Central

    Masters, Robert C.; Pearson, Andrew J.; Glen, Tom S.; Sasam, Fabian-Cyril; Li, Letian; Dapor, Maurizio; Donald, Athene M.; Lidzey, David G.; Rodenburg, Cornelia

    2015-01-01

    The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials. PMID:25906738

  5. Revealing the mechanism of passive transport in lipid bilayers via phonon-mediated nanometre-scale density fluctuations

    NASA Astrophysics Data System (ADS)

    Zhernenkov, Mikhail; Bolmatov, Dima; Soloviov, Dmitry; Zhernenkov, Kirill; Toperverg, Boris P.; Cunsolo, Alessandro; Bosak, Alexey; Cai, Yong Q.

    2016-05-01

    The passive transport of molecules through a cell membrane relies on thermal motions of the lipids. However, the nature of transmembrane transport and the precise mechanism remain elusive and call for a comprehensive study of phonon excitations. Here we report a high resolution inelastic X-ray scattering study of the in-plane phonon excitations in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine above and below the main transition temperature. In the gel phase, for the first time, we observe low-frequency transverse modes, which exhibit a phonon gap when the lipid transitions into the fluid phase. We argue that the phonon gap signifies the formation of short-lived nanometre-scale lipid clusters and transient pores, which facilitate the passive molecular transport across the bilayer plane. Our findings suggest that the phononic motion of the hydrocarbon tails provides an effective mechanism of passive transport, and illustrate the importance of the collective dynamics of biomembranes.

  6. Deceleration of single-stranded DNA passing through a nanopore using a nanometre-sized bead structure

    NASA Astrophysics Data System (ADS)

    Goto, Yusuke; Haga, Takanobu; Yanagi, Itaru; Yokoi, Takahide; Takeda, Ken-Ichi

    2015-11-01

    DNA sequencing with a solid-state nanopore requires a reduction of the translocation speeds of single-stranded DNA (ssDNA) over 10 μs/base. In this study, we report that a nanometre-sized bead structure constructed around a nanopore can reduce the moving speed of ssDNA to 270 μs/base by adjusting the diameter of the bead and its surface chemical group. This decelerating effect originates from the strong interaction between ssDNA and the chemical group on the surface of the bead. This nanostructure was simply prepared by dip coating in which a substrate with a nanopore was immersed in a silica bead solution and then dried in an oven. As compared with conventional approaches, our novel method is less laborious, simpler to perform and more effective in reducing ssDNA translocation speed.

  7. Revealing the mechanism of passive transport in lipid bilayers via phonon-mediated nanometre-scale density fluctuations

    PubMed Central

    Zhernenkov, Mikhail; Bolmatov, Dima; Soloviov, Dmitry; Zhernenkov, Kirill; Toperverg, Boris P.; Cunsolo, Alessandro; Bosak, Alexey; Cai, Yong Q.

    2016-01-01

    The passive transport of molecules through a cell membrane relies on thermal motions of the lipids. However, the nature of transmembrane transport and the precise mechanism remain elusive and call for a comprehensive study of phonon excitations. Here we report a high resolution inelastic X-ray scattering study of the in-plane phonon excitations in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine above and below the main transition temperature. In the gel phase, for the first time, we observe low-frequency transverse modes, which exhibit a phonon gap when the lipid transitions into the fluid phase. We argue that the phonon gap signifies the formation of short-lived nanometre-scale lipid clusters and transient pores, which facilitate the passive molecular transport across the bilayer plane. Our findings suggest that the phononic motion of the hydrocarbon tails provides an effective mechanism of passive transport, and illustrate the importance of the collective dynamics of biomembranes. PMID:27175859

  8. Search for 4n contributions in the reaction 14Be(CH2,X)10He

    NASA Astrophysics Data System (ADS)

    Jones, M. D.; Kohley, Z.; Baumann, T.; Christian, G.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Haring-Kaye, R. A.; Kuchera, A. N.; Luther, B.; Mosby, S.; Smith, J. K.; Snyder, J.; Spyrou, A.; Stephenson, S. L.; Thoennessen, M.

    2016-03-01

    A previously published measurement of the ground state resonance of 10He, populated by a reaction of a 59 MeV/u 14Be beam on a deuterated polyethylene target, was further analyzed to search for 4n emission resulting from 2p removal. No evidence for 4n events was found. A lower limit of about 1 MeV was determined for a possible resonance in 12He.

  9. Phase stability of graphitelike BC{sub 4}N up to 2100 K and 7 GPa

    SciTech Connect

    Solozhenko, V.L.; Turkevich, V.Z.; Sato, Tadao

    1997-12-01

    Thermal phase stability of graphitelike BC{sub 4}N (g-BC{sub 4}N) has been studied up to 7 GPa and 2,100 K using in-situ powder diffraction of synchrotron radiation. It has been shown that the process of g-BC{sub 4}N decomposition at ambient pressure starts at 2,050 K and occurs to form highly ordered hexagonal graphitelike boron nitride (hBN) and disordered graphite. As the pressure increases up to 6.6 GPa, the temperature of the decomposition onset decreases to 1,070 K. At this pressure in the 1,070--1,400 K temperature range (decomposition degree of < 0.1), the decomposition products remain the same, whereas at higher temperatures, the decomposition of g-BC{sub 4}N is accompanied by the formation of cubic boron nitride (cBN) and disordered graphite. Measurement of 298 K equation of state of g-BC{sub 4}N results in a zero-pressure bulk modulus of 18.1 {+-} 0.2 GPa and its pressure derivative of 6.6 {+-} 0.1. Thermodynamic analysis has shown that the g-BC{sub 4}N decomposition is a nonequilibrium process and the phase itself is metastable.

  10. Generation of a large volume of clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles for cell culture studies.

    PubMed

    Liu, Aiqin; Ingham, Eileen; Fisher, John; Tipper, Joanne L

    2014-04-01

    It has recently been shown that the wear of ultra-high-molecular-weight polyethylene in hip and knee prostheses leads to the generation of nanometre-sized particles, in addition to micron-sized particles. The biological activity of nanometre-sized ultra-high-molecular-weight polyethylene wear particles has not, however, previously been studied due to difficulties in generating sufficient volumes of nanometre-sized ultra-high-molecular-weight polyethylene wear particles suitable for cell culture studies. In this study, wear simulation methods were investigated to generate a large volume of endotoxin-free clinically relevant nanometre-sized ultra-high-molecular-weight polyethylene wear particles. Both single-station and six-station multidirectional pin-on-plate wear simulators were used to generate ultra-high-molecular-weight polyethylene wear particles under sterile and non-sterile conditions. Microbial contamination and endotoxin levels in the lubricants were determined. The results indicated that microbial contamination was absent and endotoxin levels were low and within acceptable limits for the pharmaceutical industry, when a six-station pin-on-plate wear simulator was used to generate ultra-high-molecular-weight polyethylene wear particles in a non-sterile environment. Different pore-sized polycarbonate filters were investigated to isolate nanometre-sized ultra-high-molecular-weight polyethylene wear particles from the wear test lubricants. The use of the filter sequence of 10, 1, 0.1, 0.1 and 0.015 µm pore sizes allowed successful isolation of ultra-high-molecular-weight polyethylene wear particles with a size range of < 100 nm, which was suitable for cell culture studies.

  11. The Importance of Nanometric Passivating Films on Cathodes forLi - Air Batteries

    SciTech Connect

    Adams, Brian D.; Black, Robert; Radtke, Claudio; Williams, Zach; Mehdi, Beata L.; Browning, Nigel D.; Nazar, Linda F.

    2014-12-23

    Recently, there has been a transition from fully carbonaceous positive electrodes for the aprotic lithium oxygen battery to alternative materials and the use of redox mediator additives, in an attempt to lower the large electrochemical overpotentials associated with the charge reaction. However, the stabilizing or catalytic effect of these materials can become complicated due to the presence of major side-reactions observed during dis(charge). Here, we isolate the charge reaction from the discharge by utilizing electrodes prefilled with commercial lithium peroxide with a crystallite size of about 200-800 nm. Using a combination of S/TEM, online mass spectrometry, XPS, and electrochemical methods to probe the nature of surface films on carbon and conductive Ti-based nanoparticles, we show that oxygen evolution from lithium peroxide is strongly dependent on their surface properties. Insulating TiO2 surface layers on TiC and TiN - even as thin as 3 nm*can completely inhibit the charge reaction under these conditions. On the other hand, TiC, which lacks this oxide film, readily facilitates oxidation of the bulk Li2O2 crystallites, at a much lower overpotential relative to carbon. Since oxidation of lithium oxygen battery cathodes is inevitable in these systems, precise control of the surface chemistry at the nanoscale becomes of upmost importance.

  12. The importance of nanometric passivating films on cathodes for Li-air batteries.

    PubMed

    Adams, Brian D; Black, Robert; Radtke, Claudio; Williams, Zack; Mehdi, B Layla; Browning, Nigel D; Nazar, Linda F

    2014-12-23

    Recently, there has been a transition from fully carbonaceous positive electrodes for the aprotic lithium oxygen battery to alternative materials and the use of redox mediator additives, in an attempt to lower the large electrochemical overpotentials associated with the charge reaction. However, the stabilizing or catalytic effect of these materials can become complicated due to the presence of major side-reactions observed during dis(charge). Here, we isolate the charge reaction from the discharge by utilizing electrodes prefilled with commercial lithium peroxide with a crystallite size of about 200-800 nm. Using a combination of S/TEM, online mass spectrometry, XPS, and electrochemical methods to probe the nature of surface films on carbon and conductive Ti-based nanoparticles, we show that oxygen evolution from lithium peroxide is strongly dependent on their surface properties. Insulating TiO2 surface layers on TiC and TiN - even as thin as 3 nm-can completely inhibit the charge reaction under these conditions. On the other hand, TiC, which lacks this oxide film, readily facilitates oxidation of the bulk Li2O2 crystallites, at a much lower overpotential relative to carbon. Since oxidation of lithium oxygen battery cathodes is inevitable in these systems, precise control of the surface chemistry at the nanoscale becomes of upmost importance. PMID:25364863

  13. Performance of intermittent aeration reactor on NH4-N removal from groundwater resources.

    PubMed

    Khanitchaidecha, W; Nakamura, T; Sumino, T; Kazama, F

    2010-01-01

    To study the effect of intermittent aeration period on ammonium-nitrogen (NH4-N) removal from groundwater resources, synthetic groundwater was prepared and three reactors were operated under different conditions--"reactor A" under continuous aeration, "reactor B" under 6 h intermittent aeration, and "reactor C" under 2 h intermittent aeration. To facilitate denitrification simultaneously with nitrification, "acetate" was added as an external carbon source with step-wise increase from 0.5 to 1.5 C/N ratio, where C stands for total carbon content in the system, and N for NH4-N concentration in the synthetic groundwater. Results show that complete NH4-N removal was obtained in "reactor B" and "reactor C" at 1.3 and 1.5 C/N ratio respectively; and partial NH4-N removal in "reactor A". These results suggest that intermittent aeration at longer interval could enhance the reactor performance on NH4-N removal in terms of efficiency and low external carbon requirement. Because of consumption of internal carbon by the process, less amount of external carbon is required. Further increase in carbon in a form of acetate (1.5 to 2.5 C/N ratios) increases removal rate (represented by reaction rate coefficient (k) of kinetic equation) as well as occurrence of free cells. It suggests that the operating condition at reactor B with 1.3 C/N ratio is more appropriate for long-term operation at a pilot-scale.

  14. Immobilization of Mn and NH4 (+)-N from electrolytic manganese residue waste.

    PubMed

    Chen, Hongliang; Liu, Renlong; Liu, Zuohua; Shu, Jiancheng; Tao, Changyuan

    2016-06-01

    The objective of this work was the immobilization of soluble manganese (Mn) and ammonium nitrogen (NH4 (+)-N) leached from electrolytic manganese residue (EMR). Immobilization of Mn was investigated via carbonation using carbon dioxide (CO2) and alkaline additives. NH4 (+)-N immobilization was evaluated via struvite precipitation using magnesium and phosphate sources. Results indicated that the immobilization efficiency of Mn using CO2 and quicklime (CaO) was higher than using CO2 and sodium hydroxide (NaOH). This higher efficiency was likely due to the slower release of OH(-) during CaO hydrolysis. The immobilization efficiency of Mn was >99.99 % at the CaO:EMR mass ratio of 0.05:1 for 20-min reaction time. The struvite precipitation of NH4 (+)-N was conducted in the carbonated EMR slurry and the immobilization efficiency was 89 % using MgCl2 · 6H2O + Na3PO4 · 12H2O at the Mg:P:N molar ratio of 1.5:1.5:1 for 90-min reaction time. A leaching test showed that the concentrations of Mn and NH4 (+)-N in the filtrate of the treated EMR were 0.2 and 9 mg/L, respectively. The combined immobilization of Mn and NH4 (+)-N was an effective pretreatment method in the harmless treatment of the EMR.

  15. Perpendicular magnetic anisotropy of Mn4N films fabricated by reactive sputtering method

    NASA Astrophysics Data System (ADS)

    Kabara, Kazuki; Tsunoda, Masakiyo

    2015-05-01

    Manganese nitride films were fabricated on MgO substrates by changing N2 flow ratio into Ar gas ( P N2 ) during reactive sputtering deposition of the films, and their crystal structures and magnetic properties were investigated. Single phased ɛ-Mn4N films were obtained when P N2 was 5%-9%, and the tetragonal lattice distortion was identified in all the Mn4N films (the lattice constant ratio, c/a = 0.99). Perpendicular magnetic anisotropy was observed in all the specimens. The Mn4N film, fabricated with P N2 = 8%, has a low saturation magnetization (Ms = 110 emu/cc) and relatively high magnetic anisotropic energy (Ku = 8.8 × 105 erg/cc). Both Ms and Ku of the films drastically changed with mixing other phases (α-Mn, β-Mn, η-Mn3N2, and possibly γ-Mn) by varying P N2 .

  16. Bottom-up substitution assembly of AuF4-n0,-+nPO3 (n = 1-4): a theoretical study of novel oxyfluoride hyperhalogen molecules and anions AuF4-n(PO3)n0,-

    NASA Astrophysics Data System (ADS)

    Yang, Yi-fan; Cui, Zhong-hua; Ding, Yi-hong

    2014-06-01

    Compounds with high electron affinity, i.e. superhalogens, have continued to attract chemists' attention, due to their potential importance in fundamental chemistry and materials science. It has now proven very effective to build up novel superhalogens with multi-positively charged centres, which are usually called 'hyperhalogens'. Herein, using AuF4- and PO3 as the model building blocks, we made the first attempt to design the Au,P-based hyperhalogen anions AuF4-n(PO3)n- (n = 1-4) at the B3LYP/6-311+G(d)&SDD and CCSD(T)/6-311+G(d)&SDD (single-point) levels (6-311+G(d) for O, F, P and SDD for Au). Notably, for all the considered Au,P systems, the ground state bears a dioxo-bonded structure with n ≤ 3, which is significantly more stable than the usually presumed mono-oxo-bonded one. Moreover, the clustering of the -PO3 moieties becomes energetically favoured for n ≥ 3. The ground states of AuP4O120,- are the first reported cage-like oxide hyperhalogens. Thus, the -PO3 moiety cannot be retained during the 'bottom-up' assembly. The vertical detachment energy (VDE) value of the most stable AuF4-n(PO3)n- (n = 1-4) ranges from 7.16 to 8.20 eV, higher than the VDE values of the corresponding building blocks AuF4- (7.08 eV) and PO3- (4.69 eV). The adiabatic detachment energy values of these four hyperhalogens exceed 6.00 eV. Possible generation routes for AuF4-n(PO3)n- (n = 1-4) were discussed. The presently designed oxyfluorides not only enriches the family of hyperhalogens, but also demonstrates the great importance of considering the structural transformation during the superhalogen → hyperhalogen design such as for the present Au-P based systems.

  17. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    PubMed Central

    Zhang, Qian; Mi, Wenbo; Wang, Xiaocha; Wang, Xuhui

    2015-01-01

    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom. PMID:26012892

  18. The Impact of Antiaromatic Subunits in [4n+2] π-Systems: Bispentalenes with [4n+2] π-Electron Perimeters and Antiaromatic Character.

    PubMed

    Cao, Jing; London, Gábor; Dumele, Oliver; von Wantoch Rekowski, Margarete; Trapp, Nils; Ruhlmann, Laurent; Boudon, Corinne; Stanger, Amnon; Diederich, François

    2015-06-10

    Three series of stable, neutral, π-extended bispentalene derivatives, with two pentalenes fused to a central benzene or naphthalene moiety, have been prepared through a modified double carbopalladation cascade reaction. While these chromophores feature skeletons with [4n+2] π-electron perimeters, the two 8 π-electron pentalene subunits strongly influence bonding and spectral properties. (1)H NMR spectra showed large upfield shifts of the protons in the pentalene moieties, comparable to antiaromatic monobenzopentalenes. Further investigations on magnetic ring currents through NICS-XY-scans suggest a global paratropic current and a local diatropic current at the central benzene ring in two of the series, while the third series, with a central naphthalene ring, showed more localized ring currents, with stronger paratropic ring currents on the pentalene moieties. X-ray diffraction analyses revealed planar bispentalene cores with large double- and single-bond alternation in the pentalene units, characteristic for antiaromaticity, and small alternation in the central aromatic rings. In agreement with TD-DFT calculations, both optical and electrochemical data showed much smaller HOMO-LUMO energy gaps compared to other neutral, acene-like hydrocarbons with the same number of fused rings. Both experimental and computational results suggest that the molecular properties of the presented bispentalenes are dominated by the antiaromatic pentalene-subunits despite the [4n+2] π-electron perimeter of the skeletons. PMID:25978774

  19. The Impact of Antiaromatic Subunits in [4n+2] π-Systems: Bispentalenes with [4n+2] π-Electron Perimeters and Antiaromatic Character.

    PubMed

    Cao, Jing; London, Gábor; Dumele, Oliver; von Wantoch Rekowski, Margarete; Trapp, Nils; Ruhlmann, Laurent; Boudon, Corinne; Stanger, Amnon; Diederich, François

    2015-06-10

    Three series of stable, neutral, π-extended bispentalene derivatives, with two pentalenes fused to a central benzene or naphthalene moiety, have been prepared through a modified double carbopalladation cascade reaction. While these chromophores feature skeletons with [4n+2] π-electron perimeters, the two 8 π-electron pentalene subunits strongly influence bonding and spectral properties. (1)H NMR spectra showed large upfield shifts of the protons in the pentalene moieties, comparable to antiaromatic monobenzopentalenes. Further investigations on magnetic ring currents through NICS-XY-scans suggest a global paratropic current and a local diatropic current at the central benzene ring in two of the series, while the third series, with a central naphthalene ring, showed more localized ring currents, with stronger paratropic ring currents on the pentalene moieties. X-ray diffraction analyses revealed planar bispentalene cores with large double- and single-bond alternation in the pentalene units, characteristic for antiaromaticity, and small alternation in the central aromatic rings. In agreement with TD-DFT calculations, both optical and electrochemical data showed much smaller HOMO-LUMO energy gaps compared to other neutral, acene-like hydrocarbons with the same number of fused rings. Both experimental and computational results suggest that the molecular properties of the presented bispentalenes are dominated by the antiaromatic pentalene-subunits despite the [4n+2] π-electron perimeter of the skeletons.

  20. Bacteria in the Tatahouine meteorite: nanometric-scale life in rocks.

    PubMed

    Gillet, P h; Barrat, J A; Heulin, T h; Achouak, W; Lesourd, M; Guyot, F; Benzerara, K

    2000-02-15

    We present a study of the textural signature of terrestrial weathering and related biological activity in the Tatahouine meteorite. Scanning and transmission electron microscopy images obtained on the weathered samples of the Tatahouine meteorite and surrounding soil show two types of bacteria-like forms lying on mineral surfaces: (1) rod-shaped forms (RSF) about 70-80 nm wide and ranging from 100 nm to 600 nm in length; (2) ovoid forms (OVF) with diameters between 70 and 300 nm. They look like single cells surrounded by a cell wall. Only Na, K, C, O and N with traces of P and S are observed in the bulk of these objects. The chemical analyses and electron diffraction patterns confirm that the RSF and OVF cannot be magnetite or other iron oxides, iron hydroxides, silicates or carbonates. The sizes of the RSF and OVF are below those commonly observed for bacteria but are very similar to some bacteria-like forms described in the Martian meteorite ALH84001. All the previous observations strongly suggest that they are bacteria or their remnants. This conclusion is further supported by microbiological experiments in which pleomorphic bacteria with morphology similar to the OVF and RSF objects are obtained from biological culture of the soil surrounding the meteorite pieces. The present results show that bacteriomorphs of diameter less than 100 nm may in fact represent real bacteria or their remnants. PMID:11543579

  1. A nanometric cushion for enhancing scratch and wear resistance of hard films.

    PubMed

    Gotlib-Vainshtein, Katya; Girshevitz, Olga; Sukenik, Chaim N; Barlam, David; Cohen, Sidney R

    2014-01-01

    Scratch resistance and friction are core properties which define the tribological characteristics of materials. Attempts to optimize these quantities at solid surfaces are the subject of intense technological interest. The capability to modulate these surface properties while preserving both the bulk properties of the materials and a well-defined, constant chemical composition of the surface is particularly attractive. We report herein the use of a soft, flexible underlayer to control the scratch resistance of oxide surfaces. Titania films of several nm thickness are coated onto substrates of silicon, kapton, polycarbonate, and polydimethylsiloxane (PDMS). The scratch resistance measured by scanning force microscopy is found to be substrate dependent, diminishing in the order PDMS, kapton/polycarbonate, Si/SiO2. Furthermore, when PDMS is applied as an intermediate layer between a harder substrate and titania, marked improvement in the scratch resistance is achieved. This is shown by quantitative wear tests for silicon or kapton, by coating these substrates with PDMS which is subsequently capped by a titania layer, resulting in enhanced scratch/wear resistance. The physical basis of this effect is explored by means of Finite Element Analysis, and we suggest a model for friction reduction based on the "cushioning effect" of a soft intermediate layer.

  2. A nanometric cushion for enhancing scratch and wear resistance of hard films

    PubMed Central

    Gotlib-Vainshtein, Katya; Girshevitz, Olga; Barlam, David

    2014-01-01

    Summary Scratch resistance and friction are core properties which define the tribological characteristics of materials. Attempts to optimize these quantities at solid surfaces are the subject of intense technological interest. The capability to modulate these surface properties while preserving both the bulk properties of the materials and a well-defined, constant chemical composition of the surface is particularly attractive. We report herein the use of a soft, flexible underlayer to control the scratch resistance of oxide surfaces. Titania films of several nm thickness are coated onto substrates of silicon, kapton, polycarbonate, and polydimethylsiloxane (PDMS). The scratch resistance measured by scanning force microscopy is found to be substrate dependent, diminishing in the order PDMS, kapton/polycarbonate, Si/SiO2. Furthermore, when PDMS is applied as an intermediate layer between a harder substrate and titania, marked improvement in the scratch resistance is achieved. This is shown by quantitative wear tests for silicon or kapton, by coating these substrates with PDMS which is subsequently capped by a titania layer, resulting in enhanced scratch/wear resistance. The physical basis of this effect is explored by means of Finite Element Analysis, and we suggest a model for friction reduction based on the "cushioning effect” of a soft intermediate layer. PMID:25161836

  3. Oriented nanometric aggregates of partially inverted zinc ferrite: One-step processing and tunable high-frequency magnetic properties

    SciTech Connect

    Sai, Ranajit; Endo, Yasushi; Shimada, Yutaka; Yamaguchi, Masahiro; Shivashankar, S. A.

    2015-05-07

    In this work, it is demonstrated that the in situ growth of oriented nanometric aggregates of partially inverted zinc ferrite can potentially pave a way to alter and tune magnetocrystalline anisotropy that, in turn, dictates ferromagnetic resonance frequency (f{sub FMR}) by inducing strain due to aggregation. Furthermore, the influence of interparticle interaction on magnetic properties of the aggregates is investigated. Mono-dispersed zinc ferrite nanoparticles (<5 nm) with various degrees of aggregation were prepared through decomposition of metal-organic compounds of zinc (II) and iron (III) in an alcoholic solution under controlled microwave irradiation, below 200 °C. The nanocrystallites were found to possess high degree of inversion (>0.5). With increasing order of aggregation in the samples, saturation magnetization (at 5 K) is found to decrease from 38 emu/g to 24 emu/g, while coercivity is found to increase gradually by up to 100% (525 Oe to 1040 Oe). Anisotropy-mediated shift of f{sub FMR} has also been measured and discussed. In essence, the result exhibits an easy way to control the magnetic characteristics of nanocrystalline zinc ferrite, boosted with significant degree of inversion, at GHz frequencies.

  4. Oriented nanometric aggregates of partially inverted zinc ferrite: One-step processing and tunable high-frequency magnetic properties

    NASA Astrophysics Data System (ADS)

    Sai, Ranajit; Endo, Yasushi; Shimada, Yutaka; Yamaguchi, Masahiro; Shivashankar, S. A.

    2015-05-01

    In this work, it is demonstrated that the in situ growth of oriented nanometric aggregates of partially inverted zinc ferrite can potentially pave a way to alter and tune magnetocrystalline anisotropy that, in turn, dictates ferromagnetic resonance frequency (fFMR) by inducing strain due to aggregation. Furthermore, the influence of interparticle interaction on magnetic properties of the aggregates is investigated. Mono-dispersed zinc ferrite nanoparticles (<5 nm) with various degrees of aggregation were prepared through decomposition of metal-organic compounds of zinc (II) and iron (III) in an alcoholic solution under controlled microwave irradiation, below 200 °C. The nanocrystallites were found to possess high degree of inversion (>0.5). With increasing order of aggregation in the samples, saturation magnetization (at 5 K) is found to decrease from 38 emu/g to 24 emu/g, while coercivity is found to increase gradually by up to 100% (525 Oe to 1040 Oe). Anisotropy-mediated shift of fFMR has also been measured and discussed. In essence, the result exhibits an easy way to control the magnetic characteristics of nanocrystalline zinc ferrite, boosted with significant degree of inversion, at GHz frequencies.

  5. Nanometric Gap Structure with a Fluid Lipid Bilayer for the Selective Transport and Detection of Biological Molecules.

    PubMed

    Ando, Koji; Tanabe, Masashi; Morigaki, Kenichi

    2016-08-01

    The biological membrane is a natural biosensing platform that can detect specific molecules with extremely high sensitivity. We developed a biosensing methodology by combining a model biological membrane and a nanometer-sized gap structure on a glass substrate. The model membrane comprised lithographically patterned polymeric and fluid lipid bilayers. The polymeric bilayer was bonded to a poly(dimethylsiloxane) (PDMS) sheet by using an adhesion layer with a defined thickness (lipid vesicles). Extruded lipid vesicles having a biotin moiety on the surface were used as the adhesion layer in conjunction with the biotin-streptavidin linkage. A gap structure was formed between the fluid bilayer and PDMS (nanogap junction). The thickness of the gap structure was several tens of nanometers, as determined by the thickness of the adhesion layer. The nanogap junction acted as a sensitive biosensing platform. From a mixture of proteins (cholera toxin and albumin), the target protein (cholera toxin) was selectively transported into the gap by the specific binding to a glycolipid (GM1) in the fluid bilayer and lateral diffusion. The target protein molecules were then detected with an elevated signal-to-noise ratio due to the reduced background noise in the nanometric gap. The combination of selective transport and reduced background noise drastically enhanced the sensitivity toward the target protein. The nanogap junction should have broad biomedical applications by realizing highly selective and sensitive biosensing in samples having diverse coexisting molecules. PMID:27427950

  6. In vivo assessing of nanometric changes on the surface of whole tomatoes that have been inoculated with Candida guilliermondii yeast.

    PubMed

    Infante, Esperanza Del Pilar

    2014-08-01

    The cuticle of plants that covers the epidermis of cells, an interface between the fruit and the environment, has an important role to play in fruit quality because it prevents water loss and mechanical damage while simultaneously forming a barrier as it prevents phytopathogens from entering the fruit. All these factors give rise to flaws in the appearance of the fruit, thus contributing to marketing problems in the form of financial loss. In the search for solutions to some of these problems, certain biocontrolling yeasts have been introduced in the last few years. In the study described here, the changes observed on the surface of the whole tomato were evaluated in vivo during the first 72 h after inoculation by spraying Candida guilliermondii yeast onto the fruit's surface. The measurements were taken on a nanometric scale using atomic force microscopy; images were created in both contact and tapping modes. The results showed diminished roughness of the surface, which could contribute to reduced phytopathogen adherence due to the thinner contact area. These results furthermore showed that a yeast biofilm was formed on the fruit which probably helps to improve water retention inside the fruit. PMID:24913139

  7. An enhanced photocatalytic response of nanometric TiO2 wrapping of Au nanoparticles for eco-friendly water applications

    NASA Astrophysics Data System (ADS)

    Scuderi, Viviana; Impellizzeri, Giuliana; Romano, Lucia; Scuderi, Mario; Brundo, Maria V.; Bergum, Kristin; Zimbone, Massimo; Sanz, Ruy; Buccheri, Maria A.; Simone, Francesca; Nicotra, Giuseppe; Svensson, Bengt G.; Grimaldi, Maria G.; Privitera, Vittorio

    2014-09-01

    We propose a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system in order to obtain an enhanced photocatalytic response. The system was synthesized by wrapping Au nanoparticles (~8 nm mean diameter) with a thin layer of TiO2 (~4 nm thick). The novel idea of embedding Au nanoparticles with titanium dioxide takes advantage of the presence of metal nanoparticles, in terms of electron trapping, without losing any of the TiO2 exposed surface, so as to favor the photocatalytic performance of titanium dioxide. A complete structural characterization was made by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The remarkable photocatalytic performance together with the stability of the nano-system was demonstrated by degradation of the methylene blue dye in water. The non-toxicity of the nano-system was established by testing the effect of the material on the reproductive cycle of Mytilus galloprovincialis in an aquatic environment. The originally synthesized material was also compared to conventional TiO2 with Au nanoparticles on top. The latter system showed a dispersion of Au nanoparticles in the liquid environment, due to their instability in the aqueous solution that clearly represents an environmental contamination issue. Thus, the results show that nanometric TiO2 wrapping of Au nanoparticles has great potential in eco-friendly water/wastewater purification.

  8. The nanometre-scale physiology of bone: steric modelling and scanning transmission electron microscopy of collagen-mineral structure.

    PubMed

    Alexander, Benjamin; Daulton, Tyrone L; Genin, Guy M; Lipner, Justin; Pasteris, Jill D; Wopenka, Brigitte; Thomopoulos, Stavros

    2012-08-01

    The nanometre-scale structure of collagen and bioapatite within bone establishes bone's physical properties, including strength and toughness. However, the nanostructural organization within bone is not well known and is debated. Widely accepted models hypothesize that apatite mineral ('bioapatite') is present predominantly inside collagen fibrils: in 'gap channels' between abutting collagen molecules, and in 'intermolecular spaces' between adjacent collagen molecules. However, recent studies report evidence of substantial extrafibrillar bioapatite, challenging this hypothesis. We studied the nanostructure of bioapatite and collagen in mouse bones by scanning transmission electron microscopy (STEM) using electron energy loss spectroscopy and high-angle annular dark-field imaging. Additionally, we developed a steric model to estimate the packing density of bioapatite within gap channels. Our steric model and STEM results constrain the fraction of total bioapatite in bone that is distributed within fibrils at less than or equal to 0.42 inside gap channels and less than or equal to 0.28 inside intermolecular overlap regions. Therefore, a significant fraction of bone's bioapatite (greater than or equal to 0.3) must be external to the fibrils. Furthermore, we observe extrafibrillar bioapatite between non-mineralized collagen fibrils, suggesting that initial bioapatite nucleation and growth are not confined to the gap channels as hypothesized in some models. These results have important implications for the mechanics of partially mineralized and developing tissues.

  9. Raster microdiffraction with synchrotron radiation of hydrated biopolymers with nanometre step-resolution: case study of starch granules.

    PubMed

    Riekel, C; Burghammer, M; Davies, R J; Di Cola, E; König, C; Lemke, H T; Putaux, J L; Schöder, S

    2010-11-01

    X-ray radiation damage propagation is explored for hydrated starch granules in order to reduce the step resolution in raster-microdiffraction experiments to the nanometre range. Radiation damage was induced by synchrotron radiation microbeams of 5, 1 and 0.3 µm size with ∼0.1 nm wavelength in B-type potato, Canna edulis and Phajus grandifolius starch granules. A total loss of crystallinity of granules immersed in water was found at a dose of ∼1.3 photons nm(-3). The temperature dependence of radiation damage suggests that primary radiation damage prevails up to about 120 K while secondary radiation damage becomes effective at higher temperatures. Primary radiation damage remains confined to the beam track at 100 K. Propagation of radiation damage beyond the beam track at room temperature is assumed to be due to reactive species generated principally by water radiolysis induced by photoelectrons. By careful dose selection during data collection, raster scans with 500 nm step-resolution could be performed for granules immersed in water.

  10. Raster microdiffraction with synchrotron radiation of hydrated biopolymers with nanometre step-resolution: case study of starch granules

    PubMed Central

    Riekel, C.; Burghammer, M.; Davies, R. J.; Di Cola, E.; König, C.; Lemke, H.T.; Putaux, J.-L.; Schöder, S.

    2010-01-01

    X-ray radiation damage propagation is explored for hydrated starch granules in order to reduce the step resolution in raster-microdiffraction experiments to the nanometre range. Radiation damage was induced by synchrotron radiation microbeams of 5, 1 and 0.3 µm size with ∼0.1 nm wavelength in B-type potato, Canna edulis and Phajus grandifolius starch granules. A total loss of crystallinity of granules immersed in water was found at a dose of ∼1.3 photons nm−3. The temperature dependence of radiation damage suggests that primary radiation damage prevails up to about 120 K while secondary radiation damage becomes effective at higher temperatures. Primary radiation damage remains confined to the beam track at 100 K. Propagation of radiation damage beyond the beam track at room temperature is assumed to be due to reactive species generated principally by water radiolysis induced by photoelectrons. By careful dose selection during data collection, raster scans with 500 nm step-resolution could be performed for granules immersed in water. PMID:20975219

  11. Electrical detection of magnetic domain wall in Fe4N nanostrip by negative anisotropic magnetoresistance effect

    NASA Astrophysics Data System (ADS)

    Gushi, Toshiki; Ito, Keita; Higashikozono, Soma; Takata, Fumiya; Oosato, Hirotaka; Sugimoto, Yoshimasa; Toko, Kaoru; Honda, Syuta; Suemasu, Takashi

    2016-09-01

    The magnetic structure of the domain wall (DW) of a 30-nm-thick Fe4N epitaxial film with a negative spin polarization of the electrical conductivity is observed by magnetic force microscopy and is well explained by micromagnetic simulation. The Fe4N film is grown by molecular beam epitaxy on a SrTiO3(001) substrate and processed into arc-shaped ferromagnetic nanostrips 0.3 μm wide by electron beam lithography and reactive ion etching with Cl2 and BCl3 plasma. Two electrodes mounted approximately 12 μm apart on the nanostrip register an electrical resistance at 8 K. By changing the direction of an external magnetic field (0.2 T), the presence or absence of a DW positioned in the nanostrip between the two electrodes can be controlled. The resistance is increased by approximately 0.5 Ω when the DW is located between the electrodes, which signifies the negative anisotropic magnetoresistance effect of Fe4N. The electrical detection of the resistance change is an important step toward the electrical detection of current-induced DW motion in Fe4N.

  12. Comparison of performance of genetics 4N6 FLOQSwabs™ with or without surfactant to rayon swabs.

    PubMed

    Frippiat, Christophe; Noel, Fabrice

    2016-08-01

    The collection of traces is the first step in the process of forensic genetics analysis. Currently, several different techniques are used (eg. gauze). Nevertheless, swabbing appears to be the most common of these. In a second step, the sampling devices should allow the use of preliminary tests in combination with an immunological confirmatory test (e.g. Hexagon Obti or Hemdirect). Our previous study shows that sampling with Genetics 4N6FLOQswabs™ coated with surfactant reduces by a factor of at least 100 the detection threshold of blood using two immunological tests. The aim of this work was to compare the ability to recover blood trace and the compatibility with immunological confirmatory test of various Genetics 4N6FLOQswabs™ nylon flocked swabs with or without surfactant. The results obtain in this study show that Genetics 4N6FLOQswabs™ not coated with surfactant and Human DNA free FLOQswabs™ were suitable for the used in combination with immunological blood detection tests. Nevertheless, the Genetics 4N6FLOQswabs™ not surfactant coated give a better blood trace recovery. PMID:27314974

  13. B4N and Fe3BN nitrides bands structure and theoretical determination of bulk modulus

    NASA Astrophysics Data System (ADS)

    dos Santos, A. V.

    2007-06-01

    With the evolution of material science there was some technological evolution as well as the need of finding new links which could be applied to diverse areas of knowledge. Thus, in this article, we study nitrides bands structures which contain boron, in two different stoichiometries Fe3BN and B4N. The choice of these compounds is meant to plan new links and to understand nitrides fundamental state properties facing these new crystalline structures. In order to resolve the compound band structure we used the method of linear Muffin Tin orbital (LMTO), with atomic sphere approximation (ASA). By using this method we obtained the energy of formation as a function of the lattice parameter as one of the results. We find the equilibrium lattice parameter of 6.9755 a.u., for the Fe3BN nitride, and in B4N, we have 6.8589 a.u. We also discuss in this article the charge transference between sites and the influence of pressure on the compound properties, as well as the Bulk modulus that is 239.82 GPa for Fe3BN and 105.48 GPa for B4N. We show the behaviour of the density of states (DOS) of the new band structure found for the proposed crystalline structure Fe3BN, in which the B atom replace the Fe atom in the corner of the structure γ‧- Fe4N.

  14. Transverse anisotropic magnetoresistance effects in pseudo-single-crystal γ'-Fe4N thin films

    NASA Astrophysics Data System (ADS)

    Kabara, Kazuki; Tsunoda, Masakiyo; Kokado, Satoshi

    2016-05-01

    Transverse anisotropic magnetoresistance (AMR) effects, for which magnetization is rotated in an orthogonal plane to the current direction, were investigated at various temperatures, in order to clarify the structural transformation from a cubic to a tetragonal symmetry in a pseudo-single-crystal Fe4N film, which is predicted from the usual in-plane AMR measurements by the theory taking into account the spin-orbit interaction and crystal field splitting of 3d bands. According to a phenomenological theory of AMR, which derives only from the crystal symmetry, a cos 2θ component ( C2 tr ) exists in transverse AMR curves for a tetragonal system but does not for a cubic system. In the Fe4N film, the C2 tr shows a positive small value (0.12%) from 300 K to 50 K. However, the C2 t r increases to negative value below 50 K and reaches to -2% at 5 K. The drastic increasing of the C2 tr demonstrates the structural transformation from a cubic to a tetragonal symmetry below 50 K in the Fe4N film. In addition, the out-of-plane and in-plane lattice constants (c and a) were precisely determined with X-ray diffraction at room temperature using the Nelson-Riely function. As a result, the positive small C2 t r above 50 K is attributed to a slightly distorted Fe4N lattice (c/a = 1.002).

  15. Comparison of performance of genetics 4N6 FLOQSwabs™ with or without surfactant to rayon swabs.

    PubMed

    Frippiat, Christophe; Noel, Fabrice

    2016-08-01

    The collection of traces is the first step in the process of forensic genetics analysis. Currently, several different techniques are used (eg. gauze). Nevertheless, swabbing appears to be the most common of these. In a second step, the sampling devices should allow the use of preliminary tests in combination with an immunological confirmatory test (e.g. Hexagon Obti or Hemdirect). Our previous study shows that sampling with Genetics 4N6FLOQswabs™ coated with surfactant reduces by a factor of at least 100 the detection threshold of blood using two immunological tests. The aim of this work was to compare the ability to recover blood trace and the compatibility with immunological confirmatory test of various Genetics 4N6FLOQswabs™ nylon flocked swabs with or without surfactant. The results obtain in this study show that Genetics 4N6FLOQswabs™ not coated with surfactant and Human DNA free FLOQswabs™ were suitable for the used in combination with immunological blood detection tests. Nevertheless, the Genetics 4N6FLOQswabs™ not surfactant coated give a better blood trace recovery.

  16. C4N2 ice in Titan’s atmosphere: reality or myth?

    NASA Astrophysics Data System (ADS)

    Anderson, Carrie; Samuelson, Robert E.; Achterberg, Richard K.; Flasar, F. M.

    2014-11-01

    Voyager 1 IRIS detected a spectral emission feature at 478 cm-1 in Titan’s atmosphere at high northern latitudes. Now one Titan year later we rediscovered it in Cassini CIRS limb spectra at 70°N. Thus far the feature has always been associated with the lower polar stratosphere during early northern spring. No known trace organic vapor in Titan’s atmosphere has a spectral feature at 478 cm-1, and the only known or suspected condensate that does is C4N2 ice. However, the C4N2 ν8 and ν9 vapor features at 472 cm-1 and 108 cm-1, respectively, have never been observed in Titan’s atmosphere, leading to a C4N2 vapor upper limit at least 2 orders of magnitude lower than equilibrium with the ice phase would suggest. In this study we analyze the spectral shapes and strengths of the 478 cm-1 feature in the IRIS and CIRS data sets in an effort to determine particle sizes, mole fractions, and vertical distributions of the putative condensate cloud responsible for the feature, and then discuss the pros and cons of its identify with C4N2 ice.

  17. Endocrine-Disrupting Potential of Bisphenol A, Bisphenol A Dimethacrylate, 4-n-Nonylphenol, and 4-n-Octylphenol in Vitro: New Data and a Brief Review

    PubMed Central

    Bonefeld-Jørgensen, Eva C.; Long, Manhai; Hofmeister, Marlene V.; Vinggaard, Anne Marie

    2007-01-01

    Background An array of environmental compounds is known to possess endocrine disruption (ED) potentials. Bisphenol A (BPA) and bisphenol A dimethacrylate (BPA-DM) are monomers used to a high extent in the plastic industry and as dental sealants. Alkylphenols such as 4-n-nonylphenol (nNP) and 4-n-octylphenol (nOP) are widely used as surfactants. Objectives We investigated the effect in vitro of these four compounds on four key cell mechanisms including transactivation of a) the human estrogen receptor (ER), b) the human androgen receptor (AR), c) the aryl hydrocarbon receptor (AhR), and d) aromatase activity. Results All four compounds inhibited aromatase activity and were agonists and antagonists of ER and AR, respectively. nNP increased AhR activity concentration-dependently and further increased the 2,3,7,8-tetrachlorodibenzo-p-dioxin AhR action. nOP caused dual responses with a weak increased and a decreased AhR activity at lower (10−8 M) and higher concentrations (10−5–10−4 M), respectively. AhR activity was inhibited with BPA (10−5–10−4 M) and weakly increased with BPA-DM (10−5 M), respectively. nNP showed the highest relative potency (REP) compared with the respective controls in the ER, AhR, and aromatase assays, whereas similar REP was observed for the four chemicals in the AR assay. Conclusion Our in vitro data clearly indicate that the four industrial compounds have ED potentials and that the effects can be mediated via several cellular pathways, including the two sex steroid hormone receptors (ER and AR), aromatase activity converting testosterone to estrogen, and AhR; AhR is involved in syntheses of steroids and metabolism of steroids and xenobiotic compounds. PMID:18174953

  18. Synthesis, characterization and electrochemical performance of graphene decorated with 1D NiMoO4.nH2O nanorods

    NASA Astrophysics Data System (ADS)

    Ghosh, Debasis; Giri, Soumen; Das, Chapal Kumar

    2013-10-01

    One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene based composite, which exhibited a high specific capacitance of 367 F g-1 at 5 A g-1 current density and a high energy density of 10.32 W h kg-1 at a power density of 1125 W kg-1 accompanied with long term cyclic stability.One-dimensional NiMoO4.nH2O nanorods and their graphene based hybrid composite with good electrochemical properties have been synthesized by a cost effective hydrothermal procedure. The formation of the mixed metal oxide and the composite was confirmed by XRD, XPS and Raman analyses. The morphological characterizations were carried out using FESEM and TEM analyses. The materials were subjected to electrochemical characterization through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) studies with 6 M KOH as the supporting electrolyte. For NiMoO4.nH2O, a maximum specific capacitance of 161 F g-1 was obtained at 5 A g-1 current density, accompanied with an energy density of 4.53 W h kg-1 at a steady power delivery rate of 1125 W kg-1. The high utility of the pseudocapacitive NiMoO4.nH2O was achieved in its graphene

  19. Self-assembly of organic monolayers as protective and conductive bridges for nanometric surface-mount applications.

    PubMed

    Platzman, Ilia; Haick, Hossam; Tannenbaum, Rina

    2010-09-01

    In this work, we present a novel surface-mount placement process that could potentially overcome the inadequacies of the currently used stencil-printing technology, when applied to devices in which either their lateral and/or their horizontal dimensions approach the nanometric scale. Our novel process is based on the "bottom-up" design of an adhesive layer, operative in the molecular/nanoscale level, through the use of self-assembled monolayers (SAMs) that could form protective and conductive bridges between pads and components. On the basis of previous results, 1,4-phenylene diisocyanide (PDI) and terephthalic acid (TPA) were chosen to serve as the best candidates for the achievement of this goal. The quality and stability of these SAMs on annealed Cu surfaces (Rrms=0.15-1.1 nm) were examined in detail. Measurements showed that the SAMs of TPA and PDI molecules formed on top of Cu substrates created thermally stable organic monolayers with high surface coverage (∼90%), in which the molecules were closely packed and well-ordered. Moreover, the molecules assumed a standing-up phase conformation, in which the molecules bonded to the Cu substrate through one terminal functional group, with the other terminal group residing away from the substrate. To examine the ability of these monolayers to serve as "molecular wires," i.e., the capability to provide electrical conductivity, we developed a novel fabrication method of a parallel plate junction (PPJ) in order to create symmetric Cu-SAM-Cu electrical junctions. The current-bias measurements of these junctions indicated high tunneling efficiency. These achievements imply that the SAMs used in this study can serve as conductive molecular bridges that can potentially bind circuital pads/components. PMID:20804143

  20. Laser Spectroscopy of GdPO4 . nH2O:Eu Nanomaterials.

    PubMed

    Lu, Shaozhe; Zhang, Jiahua; Zhang, Jishen; Shulin, Zhang E; Zhao, Haifeng; Luo, Yongshi

    2016-04-01

    One-dimensional GdPO4 . nH2O:Eu nanowires and nanorods of different sizes and the same structure were synthesized by hydrothermal method. Nanowire and nanorods had width and length of about 10 nm/50 nm and 80 nm/1 µm, respectively. Adjusting reaction system PH value by adding alkali metal NaOH, the size and shape of the product can be tuned. The high resolution spectra, excitation spectra, and laser selective excitation spectra at low temperature were determined. Nanorod compared with nanowire, photoluminescence was enhanced, and the excitation spectrum and laser selective excitation spectra were broadened. These results suggest that Eu3+ in GdPO4 . nH20 nanorod and nanowire were located in different local environments. PMID:27451675

  1. Extrinsic anomalous Hall effect in epitaxial Mn{sub 4}N films

    SciTech Connect

    Meng, M.; Wu, S. X. Ren, L. Z.; Zhou, W. Q.; Wang, Y. J.; Wang, G. L.; Li, S. W.

    2015-01-19

    Anomalous Hall effect (AHE) in ferrimagnetic Mn{sub 4}N epitaxial films grown by molecular-beam epitaxy is investigated. The longitudinal conductivity σ{sub xx} is within the superclean regime, indicating Mn{sub 4}N is a highly conducting material. We further demonstrate that the AHE signal in 40-nm-thick films is mainly due to the extrinsic contributions based on the analysis fitted by ρ{sub AH}=a′ρ{sub xx0}+bρ{sub xx}{sup 2} and σ{sub AH}∝σ{sub xx}. Our study not only provide a strategy for further theoretical work on antiperovskite manganese nitrides but also shed promising light on utilizing their extrinsic AHE to fabricate spintronic devices.

  2. Search for coupling in ferromagnetic/superconducting multilayers: Fe{sub 4}N/NbN

    SciTech Connect

    Mattson, J.E.; Potter, C.D.; Conover, M.J.; Sowers, C.H.; Bader, S.D.

    1997-09-01

    Structural, magnetic, and superconducting properties of ferromagnetic/superconducting multilayers of Fe{sub 4}N/NbN are examined. The onset of superconductivity occurs at NbN layer thickness of {approximately}100 {Angstrom}. Below this thickness ferromagnetism of the Fe{sub 4}N layers is observed. Above this thickness superconductivity of the NbN is also observed, but there is no evidence for interlayer magnetic or superconductive coupling. The results are used in the formulation of guidelines for future searches of novel interlayer coupling phenomena. The superconducting critical field curves are reasonably well described within the framework of the theory for ferromagnetic/superconducting multilayers. {copyright} {ital 1997 American Vacuum Society.}

  3. Structure determination of (Fe3O4)n+(n = 1 - 3) clusters via DFT

    NASA Astrophysics Data System (ADS)

    Li, Yanhua; Cai, Congzhong; Zhao, Chengjun; Gu, Yonghong

    2016-07-01

    In virtue of the particle swarm optimization (PSO) algorithm, the global minimum candidate structures with the lowest energy for (Fe3O4)n(n = 1 - 3) clusters were obtained by first-principles structural searches. The geometric structures and spin configurations of three cationic (Fe3O4)n+(n = 1 - 3) clusters have been identified for the first time by comparing the experimental IR spectra with the calculated results from density functional theory by using different exchange-correlation functionals. It is found that the lowest energy structures of these clusters are of a shape of hat, boat and tower, respectively, with a ferrimagnetic arrangement of spins, and M06L functional is more suitable for Fe3O4 clusters than other ones.

  4. 4'''-N-demethylspiramycin derivatives: synthesis and evaluation of effectiveness against drug-resistant bacteria.

    PubMed

    Sunazuka, Toshiaki; Shudo, Hiroko; Nagai, Kenichiro; Yoshida, Kiminari; Yamaguchi, Yukie; Hanaki, Hideaki; Omura, Satoshi

    2008-03-01

    18-amino-4''-O-benzoyl-4'''-N-demethyl-18-deoxospiramycins were designed and synthesized. Synthetic strategy involved selective demethylation of the dimethylamino group in forosamine, benzoylation of the hydroxyl group at the C4'' position and reductive N-amination of the formyl group. Antibacterial characteristics of spiramycin derivatives were tested. The derivatives exhibited promising activity against drug-resistant bacterial strains. PMID:18503196

  5. Bu4N+ alkoxide-initiated/autocatalytic addition reactions with organotrimethylsilanes.

    PubMed

    Das, Manas; O'Shea, Donal F

    2014-06-20

    The use of Me3SiO(-)/Bu4N(+) as a general activator of organotrimethylsilanes for addition reactions has been established. The broad scope of the method offers trimethylsilanes (including acetate, allyl, propargyl, benzyl, dithiane, heteroaryl, and aryl derivatives) as bench-stable organometallics that can be readily utilized as carbanion equivalents for synthesis. Reactions are achieved at rt without the requirement of specialized precautions that are commonplace for other organometallics.

  6. Nqrs Data for C8H12BCuF4N4 (Subst. No. 1102)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H12BCuF4N4 (Subst. No. 1102)

  7. Anomalous Hall effects in pseudo-single-crystal γ'-Fe4N thin films

    NASA Astrophysics Data System (ADS)

    Kabara, Kazuki; Tsunoda, Masakiyo; Kokado, Satoshi

    2016-05-01

    The anomalous Hall effects (AHE) were investigated at various temperatures for the pseudo-single-crystal Fe4N films, deposited on MgO substrates with changing the degree of order (S) of the nitrogen site. Both the anomalous Hall resistivity and the longitudinal resistivity simply decrease with lowering temperature for all the specimens. The AHE of the Fe4N films is presumed to arise from an intrinsic mechanism because of the relationship between the anomalous Hall resistivity and longitudinal resistivity. The anomalous Hall conductivity, σAH, exhibits a specific behavior at low temperature. In the case of the film with S = 0.93, the σAH drastically drops below 50 K, while it simply increases with lowering temperature in the range of 50-300 K. This low-temperature anomaly decays with decreasing S of the film and nearly vanishes in the films with low S. The threshold temperature and the dependence on S of the low-temperature anomaly of the σAH well correspond to those of the anisotropic magnetoresistance effects in the Fe4N films, reported in the literatures. From these results, it is suggested that the low-temperature anomaly of the σAH originates from the crystal field effect which reflects the structural transformation from a cubic to a tetragonal symmetry below 50 K and provides a modulation of the orbital angular momentum of the 3d orbitals at the Fermi level.

  8. Nano-crystalline silicon solar cell architecture with absorption at the classical 4n2 limit

    SciTech Connect

    Biswas, Rana; Xu, Chun

    2011-07-04

    We develop a periodically patterned conformal photonic-plasmonic crystal based solar architecture for a nano-crystalline silicon solar cell, through rigorous scattering matrix simulations. The solar cell architecture has a periodic array of tapered silver nano-pillars as the back-reflector coupled with a conformal periodic structure at the top of the cell. The absorption and maximal current, averaged over the entire range of wavelengths, for this solar cell architecture is at the semi-classical 4n{sup 2} limit over a range of common thicknesses (500-1500 nm) and slightly above the 4n{sup 2} limit for a 500 nm nc-Si cell. The absorption exceeds the 4n{sup 2} limit, corrected for reflection loss at the top surface. The photonic crystal cell current is enhanced over the flat Ag back-reflector by 60%, for a thick 1000 nm nc-Si layer, where predicted currents exceed 31 mA/cm{sup 2}. The conformal structure at the top surface focuses light within the absorber layer. There is plasmonic concentration of light, with intensity enhancements exceeding 7, near the back reflector that substantially enhances absorption.

  9. Singlet oxygen plays a key role in the toxicity and DNA damage caused by nanometric TiO2 in human keratinocytes

    NASA Astrophysics Data System (ADS)

    Fenoglio, Ivana; Ponti, Jessica; Alloa, Elisa; Ghiazza, Mara; Corazzari, Ingrid; Capomaccio, Robin; Rembges, Diana; Oliaro-Bosso, Simonetta; Rossi, François

    2013-06-01

    Nanometric TiO2 has been reported to be cytotoxic and genotoxic in different in vitro models when activated by UV light. However, a clear picture of the species mediating the observed toxic effects is still missing. Here, a nanometric TiO2 powder has been modified at the surface to completely inhibit its photo-catalytic activity and to inhibit the generation of all reactive species except for singlet oxygen. The prepared powders have been tested for their ability to induce strand breaks in plasmid DNA and for their cytotoxicity and genotoxicity toward human keratinocyte (HaCaT) cells (100-500 μg mL-1, 15 min UVA/B exposure at 216-36 mJ m-2 respectively). The data reported herein indicate that the photo-toxicity of TiO2 is mainly triggered by particle-derived singlet oxygen. The data presented herein contribute to the knowledge of structure-activity relationships which are needed for the design of safe nanomaterials.Nanometric TiO2 has been reported to be cytotoxic and genotoxic in different in vitro models when activated by UV light. However, a clear picture of the species mediating the observed toxic effects is still missing. Here, a nanometric TiO2 powder has been modified at the surface to completely inhibit its photo-catalytic activity and to inhibit the generation of all reactive species except for singlet oxygen. The prepared powders have been tested for their ability to induce strand breaks in plasmid DNA and for their cytotoxicity and genotoxicity toward human keratinocyte (HaCaT) cells (100-500 μg mL-1, 15 min UVA/B exposure at 216-36 mJ m-2 respectively). The data reported herein indicate that the photo-toxicity of TiO2 is mainly triggered by particle-derived singlet oxygen. The data presented herein contribute to the knowledge of structure-activity relationships which are needed for the design of safe nanomaterials. Electronic supplementary information (ESI) available: (1) ζ potential as a function of pH; (2) crystalline phase (XRD); (3) UV

  10. Search for evidence of C4N2 on Titan with new spectroscopic data

    NASA Astrophysics Data System (ADS)

    Jolly, A.; Benilan, Y.; Fayt, A.; Nixon, C.; Jennings, D.; Anderson, C.; Bjoraker, G.

    2013-09-01

    The Composite Infrared Spectrometer (CIRS) onboard Cassini has recorded spectra in the far and mid-infrared since 2004 with a spectral resolution of up to 0.5 cm-1. Mismatch between observed spectra and model spectra obtained from the available line lists has led us to study the spectroscopic parameters of HC3N, C4H2 and C2N2, the longest gas phase carbon chains observed so far on Titan. Band intensities, hot band intensities, and line lists were systematically verified by comparison with new laboratory spectra. Erroneous band intensities as well as an absence or shortage of hot band transitions in the line lists leading to model-data mismatches and inaccurate quantifications have been found. Improvement in the spectroscopic parameters has led to the detection of 13C isotopologues of HC3N [1] and C4H2 [2]. The study on C2N2 opens the way to the detection of 15N isotopologues whose abundances could give some clues to understand the origin and the evolution of Titan's atmosphere [3]. Also, the higher accuracy of spectroscopic data used to model CIRS spectra will facilitate the search for longer carbon chains on Titan such as HC5N, C6H2 and C4N2. Our recent measurements obtained at the SOLEIL synchrotron far infrared beam line of band intensities of C4N2 in the far and mid infrared domain have shown strong discrepancies with previous results [4]. Following the intensity measurements, a careful analysis of high resolution data has led to the first line lists for C4N2, which gives us the chance to determine precise abundance upper limits of this molecule in Titan's atmosphere.

  11. Vibrational and multinuclear NMR spectra of anionic mercuriomethanes [CH 4-n(HgX) n] n-

    NASA Astrophysics Data System (ADS)

    Breitinger, D. K.; Krumphanzl, U.; Moll, M.

    1990-03-01

    Vibrational spectra of solid sodium sulfitomercuriomethanates Na n[CH 4-n(HgSO 3) n]·nH 2O (2 ≤ and ≤ 4) exhibit high frequencies of the valence vibrations ν as(SO 3) > ν s(SO 3) (average 1057 cm -1) with big differences ν as - ν s (mean 104 cm -1), and ν(HgS) vibrations in the 200 to 230 cm -1 range, thus indicating S-coordinated sulfite ligands. Force field calculations for the ion [C(HgSO 3) 4] 4- yield high force constants K(S-O) = 605 N/m, K(Hg-S) = 258 N/m, and even K(C-Hg) = 181 N/m.- For thiosulfatomercuriomethanates [CH 4-n(HgS 2O 3] n- (1 ≤ n ≤ 4) in aqueous solutions Raman spectra suggest S-coordination with high ν as(SO 3) and ν s(SO 3) (average 1130 cm -1), and low ν(S-S) (˜420 cm -1) frequencies, and strong ν(Hg-S) bands (˜250 cm -1). From 1H, 13C and 199Hg NMR data is concluded that the CHg bond strengths in the series decrease on a lower level than in other mercuriomethanes.- On the whole, the electronic properties of the peripheral ligands X in the mercuriomethanes CH 4-n(HgX) n seem to be more important for the CHg bond strengths than the total charge.

  12. The Radiative Transfer Of CH{sub 4}-N{sub 2} Plasma Arc

    SciTech Connect

    Benallal, R.; Liani, B.

    2008-09-23

    Any physical modelling of a circuit-breaker arc therefore requires an understanding of the radiated energy which is taken into account in the form of a net coefficient. The evaluation of the net emission coefficient is performed by the knowledge of the chemical plasma composition and the resolution of the radiative transfer equation. In this paper, the total radiation which escapes from a CH{sub 4}-N{sub 2} plasma is calculated in the temperature range between 5000 and 30000K on the assumption of a local thermodynamic equilibrium and we have studied the nitrogen effect in the hydrocarbon plasmas.

  13. Critical fields of Fe{sub 4}N/NbN ferromagnetic/superconducting multilayers

    SciTech Connect

    Mattson, J.E.; Potter, C.D.; Conover, M.J.; Sowers, C.H.; Bader, S.D.

    1997-01-01

    Structural, magnetic, and superconducting properties of ferromagnetic/superconducting multilayers of Fe{sub 4}N/NbN are explored for a variety of thickness combinations. The superconducting properties show that 11 {Angstrom} ferromagnetic layers are sufficient to decouple the superconducting layers and to yield anisotropic behavior. The upper critical field data are well described by theory for ferromagnetic/superconducting multilayers. This analysis yields an interfacial parameter which characterizes the electron scattering at the ferromagnetic/superconducting boundary. {copyright} {ital 1997} {ital The American Physical Society}

  14. Diffusion and separation of CH4/N2 in pillared graphene nanomaterials: A molecular dynamics investigation

    NASA Astrophysics Data System (ADS)

    Zhou, Sainan; Lu, Xiaoqing; Wu, Zhonghua; Jin, Dongliang; Guo, Chen; Wang, Maohuai; Wei, Shuxian

    2016-09-01

    Diffusion and separation of CH4/N2 in pillared graphene were investigated by molecular dynamics. The pillared graphene with (6, 6) carbon nanotube (CNT) exhibited the higher diffusion and selectivity of CH4 over N2 than that with (7, 7) CNT due to the cooperative effect of pore topological characteristics and interaction energy. The stronger interaction facilitated CH4 to enter CNT prior to N2, and higher pressure promoted CH4 to pass CNT more easily. The relative concentrations profiles showed that CH4 reached equilibrium state faster than N2 at low pressure. Our results highlight potential use of pillared graphene in gas purification and separation.

  15. Static hyperpolarizability of the van der Waals complex CH(4)-N(2).

    PubMed

    Kalugina, Yulia N; Buldakov, Mikhail A; Cherepanov, Victor N

    2012-12-15

    The static first hyperpolarizability of the van der Waals CH(4)-N(2) complex was calculated. The calculations were carried out in the approximation of the rigid interacting molecules for a broad range of intermolecular separations (R = 6-40 a(0)) and for six configurations at CCSD(T) level of theory using the correlation consistent aug-cc-pVTZ basis set with the basis set superposition error correction. It was shown that the long-range classical approximation, including the terms up to R(-6), is in a good agreement with ab initio calculations for R > 11 a(0). It was found out that for the family of most stable configurations of the complex, the first hyperpolarizability invariants practically do not change (the changes are less than 0.1%). Under forming the stable van der Waals CH(4)-N(2) complex, the intensity and degree of depolarization of the hyper-Rayleigh scattering are noticeable decreased (by ∼10%) to be compared with the free CH(4) and N(2) molecules. PMID:22903865

  16. Biodegradation and utilization of 4-n-nonylphenol by Aspergillus versicolor as a sole carbon and energy source.

    PubMed

    Krupiński, Mariusz; Janicki, Tomasz; Pałecz, Bartłomiej; Długoński, Jerzy

    2014-09-15

    4-n-Nonylphenol (4-n-NP) is an environmental pollutant with endocrine-disrupting activities that is formed during the degradation of nonylphenol polyethoxylates, which are widely used as surfactants. Utilization of 4-n-NP by the filamentous fungus Aspergillus versicolor as the sole carbon and energy source was investigated. By means of gas chromatography-mass spectrometry, we showed that in the absence of any carbon source other than 4-n-NP in the medium, A. versicolor completely removed the xenobiotic (100 mg L(-1)) after 3 d of cultivation. Moreover, mass spectrometric analysis of intracellular extracts led to the identification of eight intermediates. The mineralization of the xenobiotic in cultures supplemented with 4-n-NP [ring-(14)C(U)] as a growth substrate was also assessed. After 3 d of incubation, approximately 50% of the initially applied radioactivity was recovered in the form of (14)CO2, proving that this xenobiotic was completely metabolized and utilized by A. versicolor as a carbon source. Based on microscopic analysis, A. versicolor is capable of germinating spores under such conditions. To confirm these observations, a microcalorimetric method was used. The results show that even the highest amount of 4-n-NP initiates heat production in the fungal samples, proving that metabolic processes were affected by the use of 4-n-NP as an energetic substrate. PMID:25222932

  17. High Catalytic Activity and Chemoselectivity of Sub-nanometric Pd Clusters on Porous Nanorods of CeO2 for Hydrogenation of Nitroarenes.

    PubMed

    Zhang, Sai; Chang, Chun-Ran; Huang, Zheng-Qing; Li, Jing; Wu, Zhemin; Ma, Yuanyuan; Zhang, Zhiyun; Wang, Yong; Qu, Yongquan

    2016-03-01

    Sub-nanometric Pd clusters on porous nanorods of CeO2 (PN-CeO2) with a high Pd dispersion of 73.6% exhibit the highest catalytic activity and best chemoselectivity for hydrogenation of nitroarenes to date. For hydrogenation of 4-nitrophenol, the catalysts yield a TOF of ∼44059 h(-1) and a chemoselectivity to 4-aminophenol of >99.9%. The superior catalytic performance can be attributed to a cooperative effect between the highly dispersed sub-nanometric Pd clusters for hydrogen activation and unique surface sites of PN-CeO2 with a high concentration of oxygen vacancy for an energetically and geometrically preferential adsorption of nitroarenes via nitro group. The high concentration of surface defects of PN-CeO2 and large Pd dispersion contribute to the enhanced catalytic activity for the hydrogenation reactions. The high chemoselectivity is mainly governed by the high Pd dispersion on the support. The catalysts also deliver high catalytic activity and selectivity for nitroaromatics with various reducible substituents into the corresponding aminoarenes.

  18. Breaking the diffraction barrier outside of the optical near-field with bright, collimated light from nanometric apertures.

    PubMed

    Stark, Peter R H; Halleck, Allison E; Larson, Dale N

    2007-11-27

    The optical diffraction limit has been the dominant barrier to achieving higher optical resolution in the fields of microscopy, photolithography, and optical data storage. We present here an approach toward imaging below the diffraction barrier. Through the exposure of photosensitive films placed a finite and known distance away from nanoscale, zero-mode apertures in thin metallic films, we show convincing, physical evidence that the propagating component of light emerging from these apertures shows a very strong degree of collimation well past the maximum extent of the near-field (lambda(0)/4n-lambda(0)/2n). Up to at least 2.5 wavelengths away from the apertures, the transmitted light exhibits subdiffraction limit irradiance patterns. These unexpected results are not explained by standard diffraction theory or nanohole-based "beaming" rationalizations. This method overcomes the diffraction barrier and makes super-resolution fluorescence imaging practical.

  19. Induction of mouthpart deformities in Chironomus riparius larvae exposed to 4-n-nonylphenol.

    PubMed

    Meregalli, G; Pluymers, L; Ollevier, F

    2001-01-01

    Chironomid mouthpart deformities have often been associated with sediment contamination and are, therefore, currently used to assess sediment quality. Deformities were only occasionally induced in laboratory bioassays. Mouthpart deformities results from a physiological disturbance during larval molting. In the past few years it has been shown that some chemicals can exert negative effects on both vertebrates and invertebrates at the level of endocrine regulation. As insect molting is hormonally regulated, we wanted to test the hypothesis that deformities are induced due to a hormonal disruption in the developmental process. The aim of the present study was to test whether the endocrine disrupter, 4-n-nonylphenol (4NP), induces mouthpart deformities in chironomids. A laboratory bioassay was performed exposing Chironomus riparius larvae to 10, 50 and 100 micrograms l-1 4NP. Survival of the larvae was not affected by the tested concentrations, but the frequency of mentum deformities increased significantly (P < 0.01) after exposure to 4NP. PMID:11202727

  20. Repairing DNA damage in xeroderma pigmentosum: T4N5 lotion and gene therapy.

    PubMed

    Zahid, Sarwar; Brownell, Isaac

    2008-04-01

    Patients with xeroderma pigmentosum (XP) have defective DNA repair and are at a high risk for cutaneous malignancies. Standard treatments for XP are limited in scope and effectiveness. Understanding the molecular etiology of XP has led to the development of novel therapeutic approaches, including enzyme and gene therapies. One new topical treatment utilizing bacteriophage T4 endonuclease 5 (T4N5) in a liposomal lotion is currently in clinical trials and has received a Fast Track designation from the FDA. Gene therapy for XP, while making leaps in preclinical studies, has been slower to develop due to tactical hurdles, but seems to have much potential for future treatment. If these treatments prove effective in lowering the risk of cancer in patients with XP, they may also be found useful in reducing skin cancers in other at-risk patient populations.

  1. Nitrogen Incorporation in CH4-N2 Photochemical Aerosol Produced by Far Ultraviolet Irradiation

    PubMed Central

    Jimenez, Jose L.; Yung, Yuk L.; Toon, Owen B.; Tolbert, Margaret A.

    2012-01-01

    Abstract Nitrile incorporation into Titan aerosol accompanying hydrocarbon chemistry is thought to be driven by extreme UV wavelengths (λ<120 nm) or magnetospheric electrons in the outer reaches of the atmosphere. Far UV radiation (120–200 nm), which is transmitted down to the stratosphere of Titan, is expected to affect hydrocarbon chemistry only and not initiate the formation of nitrogenated species. We examined the chemical properties of photochemical aerosol produced at far UV wavelengths, using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), which allows for elemental analysis of particle-phase products. Our results show that aerosol formed from CH4/N2 photochemistry contains a surprising amount of nitrogen, up to 16% by mass, a result of photolysis in the far UV. The proportion of nitrogenated organics to hydrocarbon species is shown to be correlated with that of N2 in the irradiated gas. The aerosol mass greatly decreases when N2 is removed, which indicates that N2 plays a major role in aerosol production. Because direct dissociation of N2 is highly improbable given the immeasurably low cross section at the wavelengths studied, the chemical activation of N2 must occur via another pathway. Any chemical activation of N2 at wavelengths >120 nm is presently unaccounted for in atmospheric photochemical models. We suggest that reaction with CH radicals produced from CH4 photolysis may provide a mechanism for incorporating N into the molecular structure of the aerosol. Further work is needed to understand the chemistry involved, as these processes may have significant implications for how we view prebiotic chemistry on early Earth and similar planets. Key Words: Titan—Photochemical aerosol—CH4-N2 photolysis—Far UV—Nitrogen activation. Astrobiology 12, 315–326. PMID:22519972

  2. A simple and sensitive method for the determination of 4-n-octylphenol based on multi-walled carbon nanotubes modified glassy carbon electrode.

    PubMed

    Zheng, Qiaoli; Yang, Ping; Xu, He; Liu, Jianshe; Jin, Litong

    2012-01-01

    A simple and sensitive electroanalytical method was presented for the determination of 4-n-octylphenol (OP) based on multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE). OP was directly oxidized on the MWCNTs/GCE, and the electrochemical oxidation mechanism was demonstrated by a one-electron and one-proton process in the reaction. The oxidation peak current of OP was significantly enhanced by the use of MWCNTs/GCE compared with those of bare glassy carbon electrode, suggesting that the modified electrode can remarkably improve the performance for OP determination. Factors influencing the detection processes were optimized. Under these optimal conditions, a linear relationship between concentration of OP and current response was obtained in the range of 5 x 10(-8) to 1 x 10(-5) mol/L with a detection limit of 1.5 x 10(-8) mol/L and correlation coefficient 0.9986. The modified electrode showed good selectivity, sensitivity, reproducibility and high stability.

  3. Fabrication of MgAl{sub 2}O{sub 4} tunnel barrier by radio frequency-sputtering method and magnetoresistance effect through it with Fe or Fe{sub 4}N ferromagnetic electrode

    SciTech Connect

    Tsunoda, Masakiyo; Chiba, Ryoichi; Kabara, Kazuki

    2015-05-07

    Spinel MgAl{sub 2}O{sub 4} thin films were deposited on MgO single-crystal substrates and epitaxial Fe (or Fe{sub 4}N) thin films by RF-sputtering from a ceramic target. Epitaxial relationship was confirmed by X-ray diffraction analysis between the crystalline spinel MgAl{sub 2}O{sub 4} films and the respective substrate and underlayers, while no diffraction peak was observed from the films deposited on amorphous substrates. Spin-valve type magnetic tunnel junctions (MTJs) with a stacking structure of Fe [Fe{sub 4}N]/MgAl{sub 2}O{sub 4}/CoFeB/Ru/Fe/MnIr exhibited normal [inverse] tunnel magnetoresistance (TMR) effect, reflecting the sign of spin polarization of Fe [Fe{sub 4}N]. The maximum magnitude of the TMR ratio obtained for the Fe-based and Fe{sub 4}N-based MTJs was 67% and 18%, respectively. The resistance area product values of the MTJs were significantly larger than the reported values for the MTJs with a post-oxidized spinel MgAl{sub 2}O{sub 4} barrier.

  4. Fabrication of MgAl2O4 tunnel barrier by radio frequency-sputtering method and magnetoresistance effect through it with Fe or Fe4N ferromagnetic electrode

    NASA Astrophysics Data System (ADS)

    Tsunoda, Masakiyo; Chiba, Ryoichi; Kabara, Kazuki

    2015-05-01

    Spinel MgAl2O4 thin films were deposited on MgO single-crystal substrates and epitaxial Fe (or Fe4N) thin films by RF-sputtering from a ceramic target. Epitaxial relationship was confirmed by X-ray diffraction analysis between the crystalline spinel MgAl2O4 films and the respective substrate and underlayers, while no diffraction peak was observed from the films deposited on amorphous substrates. Spin-valve type magnetic tunnel junctions (MTJs) with a stacking structure of Fe [Fe4N]/MgAl2O4/CoFeB/Ru/Fe/MnIr exhibited normal [inverse] tunnel magnetoresistance (TMR) effect, reflecting the sign of spin polarization of Fe [Fe4N]. The maximum magnitude of the TMR ratio obtained for the Fe-based and Fe4N-based MTJs was 67% and 18%, respectively. The resistance area product values of the MTJs were significantly larger than the reported values for the MTJs with a post-oxidized spinel MgAl2O4 barrier.

  5. Oxide nanowires for spintronics: materials and devices.

    PubMed

    Tian, Yufeng; Bakaul, Saidur Rahman; Wu, Tom

    2012-03-01

    Spintronics, or spin-based data storage and manipulation technology, is emerging as a very active research area because of both new science and potential technological applications. As the characteristic lengths of spin-related phenomena naturally fall into the nanometre regime, researchers start applying the techniques of bottom-up nanomaterial synthesis and assembly to spintronics. It is envisaged that novel physics regarding spin manipulation and domain dynamics can be realized in quantum confined nanowire-based devices. Here we review the recent breakthroughs related to the applications of oxide nanowires in spintronics from the perspectives of both material candidates and device fabrication. Oxide nanowires generally show excellent crystalline quality and tunable physical properties, but more efforts are imperative as we strive to develop novel spintronic nanowires and devices.

  6. Tetraalklylammonium polyoxoanionic oxidation catalysts

    DOEpatents

    Ellis, P.E.; Lyons, J.E.; Myers, H.K. Jr.; Shaikh, S.N.

    1998-10-06

    Alkanes are catalytically oxidized in air or oxygen using iron-substituted polyoxoanions (POAs) of the formula: H{sub e{minus}z}[(n-C{sub 4}H{sub 9}){sub 4}N]{sub z}(XM{sub 11}M{prime}O{sub 39}){sup {minus}e}. The M{prime} (e.g., iron(III)/iron(II)) reduction potential of the POAs is affected by selection of the central atom X and the framework metal M, and by the number of tetrabutyl-ammonium groups. Decreased Fe(III)/Fe(II) reduction potential has been found to correlate to increased oxidation activity.

  7. Tetraalykylammonium polyoxoanionic oxidation catalysts

    DOEpatents

    Ellis, Paul E.; Lyons, James E.; Myers, Jr., Harry K.; Shaikh, Shahid N.

    1998-01-01

    Alkanes are catalytically oxidized in air or oxygen using iron-substituted polyoxoanions (POAs) of the formula: H.sub.e-z ›(n-C.sub.4 H.sub.9).sub.4 N!.sub.z (XM.sub.11 M'O.sub.39).sup.-e The M' (e.g., iron(III)/iron(II)) reduction potential of the POAs is affected by selection of the central atom X and the framework metal M, and by the number of tetrabutyl-ammonium groups. Decreased Fe(III)/Fe(II) reduction potential has been found to correlate to increased oxidation activity.

  8. Cationic motions and phase transitions in [(CH 3) 4N] 2SO 4·4H 2O, [(CH 3) 4N] 2SO 4, and [(CH 3) 4N] 2SeO 4 as studied by 1H NMR, differential thermal analysis, and X-ray powder diffraction techniques

    NASA Astrophysics Data System (ADS)

    Sato, Setsuko; Endo, Midori; Hara, Naoki; Nakamura, Daiyu; Ikeda, Ryuichi

    1995-02-01

    Cationic reorientations have been studied in solid [(CH 3) 4N] 2SO 4·4H 2O, [(CH 3) 4N] 2SO 4, and [(CH 3) 4N] 2SeO 4 by measuring 1H NMR spin-lattice relaxation times, T1. These motions have been discussed in association with the crystal structures and the phase transitions examined by X-ray powder diffraction and differential thermal analysis, respectively. In crystals of [(CH 3) 4N] 2SO 4·4H 2O, there are two kinds of cations distorted from regular tetrahedra. T1 is calculated according to the interpretation that two T1 minima are due to the two inequivalent (NH 3) 4N + ions reorienting at different frequencies. The result shows that at the phase transition temperatures, the correlation times to those cationic reorientations are very different from each other in this compound in contrast with (NH 4) 2SO 4 and [(CH 3) 4N] 2CdX 4 (X = Cl and Br). For the sulfate and selenate, there is a single kind of cation which can be considered tetrahedral, and the phase transitions occur in the temperature region where the narrowing of the resonance line owing to the overall cationic reorientations starts.

  9. Determination of chromium (III) in natural water samples utilizing capillary micro-extraction on nanometre zirconium phosphate coating coupled to electrothermal atomic absorbance spectrometry.

    PubMed

    Bai, Xiaohong; Fan, Zhefeng

    2009-02-01

    A simple and sensitive method for the separation of Cr(III) in natural water was developed. The novel method was targeted on extraction of Cr(III) by using a nanometre-scale zirconium phosphate coated capillary tube, and determined by electrothermal atomic absorption spectrometry (ETAAS). The variables influencing the micro-extraction of Cr(III) including pH, sample volume, sample flow rate, eluent volume and eluent flow rate were investigated. Under the optimized conditions, the detection limit (3s) was 0.042 ng mL(-1), and the relative standard deviation (RSD) was 1.5% (c=10 ng mL(-1), n=7). The proposed method was applied to determination of Cr(III) in natural waters.

  10. Small, but perfectly formed: The microstructure of nanocrystalline oxides

    NASA Astrophysics Data System (ADS)

    Chadwick, A. V.

    2003-01-01

    There is considerable interest in nanocrystalline materials due to their unusual properties that offer the possibility of exciting technological applications. This paper concentrates on the microstructure of nanocrystalline binary oxides as revealed by X-ray absorption studies. It will be shown that these experiments yield a picture of the materials in which, even when the particles are only a few nanometres in size, the crystallites are highly ordered and the interfaces are similar to grain boundaries in normal bulk solids. This is in conflict with earlier ideas where it was often assumed the surfaces of nanocrystals and the interfaces between them were very disordered.

  11. Spherically symmetric solutions of a (4 + n)-dimensional Einstein Yang Mills model with cosmological constant

    NASA Astrophysics Data System (ADS)

    Brihaye, Yves; Hartmann, Betti

    2005-01-01

    We construct solutions of an Einstein Yang Mills system including a cosmological constant in 4 + n spacetime dimensions, where the n-dimensional manifold associated with the extra dimensions is taken to be Ricci flat. Assuming the matter and metric fields to be independent of the n extra coordinates, a spherical symmetric ansatz for the fields leads to a set of coupled ordinary differential equations. We find that for n > 1 only solutions with either one non-zero Higgs field or with all Higgs fields constant and zero gauge field function (corresponding to a Wu Yang-type ansatz) exist. We give the analytic solutions available in this model. These are 'embedded' Abelian solutions with a diverging size of the manifold associated with the extra n dimensions. Depending on the choice of parameters, these latter solutions either represent naked singularities or they possess a single horizon. We also present solutions of the effective four-dimensional Einstein Yang Mills Higgs-dilaton model, where the higher-dimensional cosmological constant induces a Liouville-type potential. The solutions are non-Abelian solutions with diverging Higgs fields, which exist only up to a maximal value of the cosmological constant.

  12. Structure, conformation and hydrogen bonding of 4-( N-methylpiperidinium)-butyric acid bromide

    NASA Astrophysics Data System (ADS)

    Dega-Szafran, Z.; Dulewicz, E.; Szafran, M.; Thaimattam, R.; Jaskolski, M.

    2007-02-01

    A 1:1 complex between 4-( N-methylpiperidinium)-butyrate inner salt (betaine) and hydrobromide, MPBUH·Br, has been characterized by single crystal X-ray analysis. The crystals are monoclinic, space group P2 1/c, with a = 8.284(1), b = 10.369(1), c = 13.809(2) Å, β = 92.26(1)°. The piperidine ring adopts a chair conformation with the (CH 2) 3COOH substituent in the axial and the CH 3 group in the equatorial positions. In the crystal, the Br - anion is engaged in a medium-strong hydrogen bond with the COOH group (O sbnd H⋯Br - = 3.141(1) Å), N +⋯Br - electrostatic interactions and in several C sbnd H⋯Br - contacts with the aliphatic groups forming a cavity in which it is enclosed. Three conformers ( 2- 4) were optimized by the B3LYP/6-31G (d, p) level of theory. The most stable is conformer 4 with the (CH 2) 3COOH substituent in the equatorial position and the CH 3 group in the axial position. The stability of the investigated conformers is controlled by electrostatic interactions between the oppositely charged groups. The FTIR spectrum of MPBUH·Br shows a strong band at 2941 cm -1 due to νOH and the νC dbnd O band at 1712 cm -1.

  13. Can Moral Hazard Be Resolved by Common-Knowledge in S4n-Knowledge?

    NASA Astrophysics Data System (ADS)

    Matsuhisa, Takashi

    This article investigates the relationship between common-knowledge and agreement in multi-agent system, and to apply the agreement result by common-knowledge to the principal-agent model under non-partition information. We treat the two problems: (1) how we capture the fact that the agents agree on an event or they get consensus on it from epistemic point of view, and (2) how the agreement theorem will be able to make progress to settle a moral hazard problem in the principal-agents model under non-partition information. We shall propose a solution program for the moral hazard in the principal-agents model under non-partition information by common-knowledge. Let us start that the agents have the knowledge structure induced from a reflexive and transitive relation associated with the multi-modal logic S4n. Each agent obtains the membership value of an event under his/her private information, so he/she considers the event as fuzzy set. Specifically consider the situation that the agents commonly know all membership values of the other agents. In this circumstance we shall show the agreement theorem that consensus on the membership values among all agents can still be guaranteed. Furthermore, under certain assumptions we shall show that the moral hazard can be resolved in the principal-agent model when all the expected marginal costs are common-knowledge among the principal and agents.

  14. Cation-Cation Interactions in [(UO2)2(OH)n](4-n) Complexes

    SciTech Connect

    Odoh, Samuel O.; Govind, Niranjan; Schreckenbach, Georg; De Jong, Wibe A.

    2013-10-07

    The structures and bonding of gas-phase [(UO2)2(OH)n]4-n (n=2-6) complexes have been studied using density functional theory (DFT), MP2 and CCSD(T) methods with particular emphasis on ground state structures featuring cation-cation interactions (CCIs) between the uranyl groups. An interesting trend is observed in the stabilities of members of this series of complexes. The structures of [(UO2)2(OH)2]2+, [(UO2)2(OH)4] and [(UO2)2(OH)6]2- featuring CCIs are found at higher energies (by 3-20 kcal/mol) in comparison to their conventional μ2-dihydroxo structures. In contrast, the CCI structures of [(UO2)2(OH)3]+ and [(UO2)2(OH)5]- are respectively almost degenerate with and lower in energy than the structures with the μ2-dihydroxo format. The origin of this trend lies in the ‘symmetry’-based need to balance the coordination numbers and effective atomic charges of each uranium center. The calculated IR vibrational frequencies provide signature probes that can be used in differentiating the lowenergy structures and in experimentally confirming the existence of the structures featuring CCIs. Analysis of the bonding in the structures of [(UO2)2(OH)3]+ and [(UO2)2(OH)5]- shows that the CCIs and bridging hydroxo between the dioxo-uranium units are mainly electrostatic in nature.

  15. Early Events in the Nonadiabatic Relaxation Dynamics of 4-(N,N-Dimethylamino)benzonitrile.

    PubMed

    Kochman, Michał A; Tajti, Attila; Morrison, Carole A; Miller, R J Dwayne

    2015-03-10

    4-(N,N-Dimethylamino)benzonitrile (DMABN) is the archetypal system for dual fluorescence. Several past studies, both experimental and theoretical, have examined the mechanism of its relaxation in the gas phase following photoexcitation to the S2 state, without converging to a single description. In this contribution, we report first-principles simulations of the early events involved in this process performed using the nonadiabatic trajectory surface hopping (TSH) approach in combination with the ADC(2) electronic structure method. ADC(2) is verified to reproduce the ground- and excited-state structures of DMABN in reasonably close agreement with previous theoretical benchmarks. The TSH simulations predict that internal conversion from the S2 state to the S1 takes place as early as 8.5 fs, on average, after the initial photoexcitation, and with no significant torsion of the dimethylamino group relative to the aromatic ring. As evidenced by supporting EOM-CCSD calculations, the population transfer from S2 to S1 can be attributed to the skeletal deformation modes of the aromatic ring and the stretching of the ring-dimethylamino nitrogen bond. The non- or slightly twisted locally excited structure is the predominant product of the internal conversion, and the twisted intramolecular charge transfer structure is formed through equilibration with the locally excited structure with no change of adiabatic state. These findings point toward a new interpretation of data from previous time-resolved experiments. PMID:26579762

  16. Structural and biological evaluation of some metal complexes of vanillin-4N-(2-pyridyl) thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; Abu El-Reash, G. M.; Al-Jahdali, M.; El-Rakhawy, El-Bastawesy R.

    2013-12-01

    The synthesis and characterization of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and U(VI)O2 complexes of vanillin-4N-(2-pyridyl) thiosemicarbazone (H2PVT) are reported. Theoretical calculations have been performed to obtain IR spectra of ligand and its complexes using AM1, Zindo/1, MM+ and PM3, methods. The Schiff base and its metal complexes have been screened for antibacterial Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus saprophyticus. H2VPT shows no apparent digestion effect on the egg albumin while Mn(II), Hg(II) and Cu(II) complexes exhibited a considerable digestion effect following the order Cu(II) > Mn(II) > Hg(II). Moreover, Ni(II) and Co(II) complexes revealed strong digestion effect. Fe(II), Mn(II), Cu(II), Zn(II) and Ni(II) acted as metal co- SOD enzyme factors, which are located in different compartments of the cell.

  17. Transport Properties of a Rarefied Ch4-N2 Gas Mixture

    NASA Astrophysics Data System (ADS)

    Fokin, L. R.; Kalashnikov, A. N.

    2016-01-01

    The area of application of the rarefied neutral methane-nitrogen gas mixture is considered. Experimental data on the transport properties of this mixture and its components were analyzed and generalized on the basis of molecular-kinetic theory relations with the use of the potentials of pair uniform and cross interactions of CH4 and N2 molecules. The parameters of three spherical symmetric three-parameter m-6 Lennard-Jones interaction potentials with a repulsive branch of varying rigidity were determined with the use of the nonlinear weight method of least squares. Tables of reference data on the viscosity of the indicated mixture and the coefficients of interdiffusion of its components were calculated for the concentration range 0-1 at temperatures 100-1150 K. Estimates of the confidential errors in determining the properties of this mixture have been made with the use of the error matrix of parameters of the indicated potentials. The results of calculations were compared with the corresponding reference data obtained earlier for the CH4-N2 gas mixture.

  18. High-voltage SPM oxidation of ZrN: materials for multiscale applications.

    PubMed

    Farkas, N; Comer, J R; Zhang, G; Evans, E A; Ramsier, R D; Dagata, J A

    2005-02-01

    Scanning probe microscope (SPM) oxidation was used to form zirconium oxide features on 200 nm thick ZrN films. The features exhibit rapid yet controlled growth kinetics, even in contact mode with 70 V dc applied between the probe tip and substrate. The features grown for times longer than 10 s are higher than 200 nm, and reach more than 1000 nm in height after 300 s. Long-time oxidation experiments and selective etching of the oxides and nitrides lead us to propose that as the oxidation reaches the silicon substrate, delamination occurs with the simultaneous formation of a thin layer of new material at the ZrN/Si interface. High-voltage oxide growth on ZrN is fast and sustainable, and the robust oxide features are promising candidates for multiscale (nanometre-to-micrometre) applications. PMID:21727433

  19. The diverse electronic properties of C4N3 monolayer under biaxial compressive strain: a theoretical study

    NASA Astrophysics Data System (ADS)

    Wu, Haiping; Liu, Yuzhen; Kan, Erjun; Ma, Yanming; Xu, Wenjie; Li, Jie; Yan, Meichen; Lu, Ruifeng; Wei, Jianfeng; Qian, Yan

    2016-07-01

    Because of the observation of half-metallicity in graphitic carbon nitride C4N3 (g-C4N3), extensive research has recently been focused on this compound. Using density-functional calculations, herein diverse electronic properties of g-C4N3 were engineered by applying biaxial compressive strain. The calculated results demonstrate that g-C4N3 preserves ferromagnetic half-metallicity when the strain is lower than  -2%, accompanied by a decrease of the half-metallic gap. When the compressive strain ranges from  -5 to  -3%, the compound turns into nonmagnetic metal. By increasing the strain on the end, it becomes a nonmagnetic semiconductor. Further investigations show that all nonmagnetic semiconductors possess a direct band gap with a value of around 1.6 eV. This fact indicates that g-C4N3 can be applied in spintronic or photovoltaic fields under a strain environment.

  20. The diverse electronic properties of C4N3 monolayer under biaxial compressive strain: a theoretical study

    NASA Astrophysics Data System (ADS)

    Wu, Haiping; Liu, Yuzhen; Kan, Erjun; Ma, Yanming; Xu, Wenjie; Li, Jie; Yan, Meichen; Lu, Ruifeng; Wei, Jianfeng; Qian, Yan

    2016-07-01

    Because of the observation of half-metallicity in graphitic carbon nitride C4N3 (g-C4N3), extensive research has recently been focused on this compound. Using density-functional calculations, herein diverse electronic properties of g-C4N3 were engineered by applying biaxial compressive strain. The calculated results demonstrate that g-C4N3 preserves ferromagnetic half-metallicity when the strain is lower than  ‑2%, accompanied by a decrease of the half-metallic gap. When the compressive strain ranges from  ‑5 to  ‑3%, the compound turns into nonmagnetic metal. By increasing the strain on the end, it becomes a nonmagnetic semiconductor. Further investigations show that all nonmagnetic semiconductors possess a direct band gap with a value of around 1.6 eV. This fact indicates that g-C4N3 can be applied in spintronic or photovoltaic fields under a strain environment.

  1. Nitrogen Incorporation in CH4-N2 Photochemical Aerosol Produced by Far UV Irradiation

    NASA Technical Reports Server (NTRS)

    Trainer, Melissa G.; Jimenez, Jose L.; Yung, Yuk L.; Toon, Owen B.; Tolbert, Margaret A.

    2012-01-01

    Nitrile incorporation into Titan aerosol accompanying hydrocarbon chemistry is thought to be driven by extreme UV wavelengths (lambda < 120 nm) or magnetospheric electrons in the outer reaches of the atmosphere. Far UV radiation (120 - 200 nm), which is transmitted down to the stratosphere of Titan, is expected to affect hydrocarbon chemistry only and not initiate the formation of nitrogenated species. We have examined the chemical properties of photochemical aerosol produced at far UV wavelengths using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), which allows for elemental analysis of particle-phase products. Our results show that aerosol formed from CH4/N2 photochemistry contains a surprising amount of nitrogen, up to 16% by mass, a result of photolysis in the far UV. The proportion of nitrogenated organics to hydrocarbon species is shown to be correlated with that of N2 in the irradiated gas. The aerosol mass greatly decreases when N2 is removed, indicating that N2 plays a major role in aerosol production. Because direct dissociation of N2 is highly improbable given the immeasurably low cross-section at the wavelengths studied, the chemical activation of N2 must occur via another pathway. Any chemical activation of N2 at wavelengths > 120 nm is presently unaccounted for in atmospheric photochemical models. We suggest that reaction with CH radicals produced from CH4 photolysis may provide a mechanism for incorporating N into the molecular structure of the aerosol. Further work is needed to understand the chemistry involved, as these processes may have significant implications for prebiotic chemistry on the early Earth and similar planets.

  2. Effects of Picoxystrobin and 4-n-Nonylphenol on Soil Microbial Community Structure and Respiration Activity

    PubMed Central

    Stenrød, Marianne; Klemsdal, Sonja S.; Norli, Hans Ragnar; Eklo, Ole Martin

    2013-01-01

    There is widespread use of chemical amendments to meet the demands for increased productivity in agriculture. Potentially toxic compounds, single or in mixtures, are added to the soil medium on a regular basis, while the ecotoxicological risk assessment procedures mainly follow a chemical by chemical approach. Picoxystrobin is a fungicide that has caused concern due to studies showing potentially detrimental effects to soil fauna (earthworms), while negative effects on soil microbial activities (nitrification, respiration) are shown to be transient. Potential mixture situations with nonylphenol, a chemical frequently occurring as a contaminant in sewage sludge used for land application, infer a need to explore whether these chemicals in mixture could alter the potential effects of picoxystrobin on the soil microflora. The main objective of this study was to assess the effects of picoxystrobin and nonylphenol, as single chemicals and mixtures, on soil microbial community structure and respiration activity in an agricultural sandy loam. Effects of the chemicals were assessed through measurements of soil microbial respiration activity and soil bacterial and fungal community structure fingerprints, together with a degradation study of the chemicals, through a 70 d incubation period. Picoxystrobin caused a decrease in the respiration activity, while 4-n-nonylphenol caused an increase in respiration activity concurring with a rapid degradation of the substance. Community structure fingerprints were also affected, but these results could not be directly interpreted in terms of positive or negative effects, and were indicated to be transient. Treatment with the chemicals in mixture caused less evident changes and indicated antagonistic effects between the chemicals in soil. In conclusion, the results imply that the application of the fungicide picoxystrobin and nonylphenol from sewage sludge application to agricultural soil in environmentally relevant concentrations, as

  3. Spin-polarization inversion at small organic molecule/Fe{sub 4}N interfaces: A first-principles study

    SciTech Connect

    Zhang, Qian; Mi, Wenbo

    2015-09-21

    We report the first-principles calculations on the electronic structure and simulation of the spin-polarized scan tunneling microscopy graphic of the small organic molecules (benzene, thiophene, and cyclopentadienyl)/Fe{sub 4}N interfaces. It is found that the plane of benzene and thiophene keeps parallel to Fe{sub 4}N surface, while that of cyclopentadienyl does not. For all the systems, the organic molecules bind strongly with Fe{sub 4}N. Due to the hybridization between molecule p{sub z} orbitals and d orbitals of Fe, i.e., Zener interaction, all the three systems realize the spin-polarization inversion, whereas the spatial spin-polarization inversion distribution shows different intensities influenced by the competition between the spin polarization of C p{sub z} and Fe d states.

  4. Characterization of an H4N2 avian influenza virus isolated from domestic duck in Dongting Lake wetland in 2009.

    PubMed

    Zhang, Hongbo; Chen, Quanjiao; Chen, Ze

    2012-02-01

    In January 2009, an H4N2 subtype of avian influenza virus [A/duck/Hunan/8-19/2009 (H4N2)] was isolated from domestic ducks in Dongting Lake wetland. The whole genome of the virus was sequenced and the results indicated that multiple gene segments of the virus had a high homology with viruses isolated from wild waterfowl, which indicated that the virus was probably transmitted from wild waterfowl to domestic ducks. Phylogenetic analysis revealed that the each gene belonged to the Eurasian lineage of avian influenza viruses, but genetic reassortment occurs between viruses of different subtypes.

  5. Multimode resistive switching in nanoscale hafnium oxide stack as studied by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Hou, Y.; Celano, U.; Goux, L.; Liu, L.; Degraeve, R.; Cheng, Y.; Kang, J.; Jurczak, M.; Vandervorst, W.

    2016-07-01

    The nanoscale resistive switching in hafnium oxide stack is investigated by the conductive atomic force microscopy (C-AFM). The initial oxide stack is insulating and electrical stress from the C-AFM tip induces nanometric conductive filaments. Multimode resistive switching can be observed in consecutive operation cycles at one spot. The different modes are interpreted in the framework of a low defect quantum point contact theory. The model implies that the optimization of the conductive filament active region is crucial for the future application of nanoscale resistive switching devices.

  6. Carbon nanotubes in electrospun polyethylene oxide nanofibres: A potential route to conducting nanofibres

    NASA Astrophysics Data System (ADS)

    Nazhipkyzy, M.; Mohan, S. D.; Davis, F. J.; Mitchell, G. R.

    2015-10-01

    Polyethylene oxide solution containing multi-walled carbon nanotubes have been electrospun onto a rotating collector to produce highly aligned arrays of electrospun nanofibers ranging in diameters from (200 - 360) nanometres. The addition of a surfactant (Triton X-100) is highly effective in dispersing carbon nanotube within an aqueous solution of polyethylene oxide and the resulting mixture can be electrospun without excessive clumping to produce nanofibers containing high loadings of nanotubes; in this case up to 5% wt thereby providing an effective route to electrically conductive nanofibres.

  7. Discontinuous ion tracks on silicon oxide on silicon surfaces after grazing-angle heavy ion irradiation

    SciTech Connect

    Carvalho, A. M. J. F.; Marinoni, M.; Touboul, A. D.; Guasch, C.; Lebius, H.; Ramonda, M.; Bonnet, J.; Saigne, F.

    2007-02-12

    Thin silicon oxide layers on silicon have been characterized by atomic force microscopy before and after swift heavy ion irradiation with 0.63 MeV/u Pb ions at grazing angle of incidence. In this letter, the authors report the observation of extended intermittent tracks at the silicon oxide (SiO{sub 2}) surface. As a result, this raises the question of the discontinuous energy deposition at the nanometric scale. This experimental overlook is of major interest for nanostructuring and surface nanoprocessing as well as with regard to reliability of electronic components and systems.

  8. Amine templating effect absent in uranyl sulfates synthesized with 1,4-n-butyldiamine

    SciTech Connect

    Jouffret, Laurent J.; Wylie, Ernest M.; Burns, Peter C.

    2013-01-15

    Two new uranyl sulfates, (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS2) and (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS3), were synthesized and their crystal structures determined. NDUS2 was obtained in highly acidic media heat-treated at 373 K and subsequently maintained at 278 K until crystals formed after two months. NDUS3 results from the degradation of NDUS2 over the course of a few days. NDUS2 and NDUS3 crystallize in the monoclinic space group P2{sub 1}/n, a=10.9075(4) A, b=10.4513(4) A, c=17.7881(7) A, {beta}=97.908(2) Degree-Sign , V=2008.52(13) A{sup 3}, Z=4, at 140 K and a=8.8570(4) A, b=7.3299(3) A, c=20.4260(9) A, {beta}=95.140(2) Degree-Sign , V=1320.74(10) A{sup 3}, Z=4, at 140 K, respectively. The compounds contain interlayer 1,4-n-butyldiammonium cations that charge-balance the anionic structural units. - Graphical abstract: Amine templating effect absent in uranyl sulfates synthesized with 1,4-diaminobutane, as shown by the synthesis of two new uranyl sulfates, (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS2) and (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS3). Highlights: Black-Right-Pointing-Pointer Two layered uranyl sulfates were synthesized. Black-Right-Pointing-Pointer Amine molecules are located in the interlayers of the compounds. Black-Right-Pointing-Pointer No templating effect of the amine was observed. Black-Right-Pointing-Pointer Amine molecules are only charge balancing cations in the structures.

  9. AF4 and AF4N protein complexes: recruitment of P-TEFb kinase, their interactome and potential functions

    PubMed Central

    Scholz, Bastian; Kowarz, Eric; Rössler, Tanja; Ahmad, Khalil; Steinhilber, Dieter; Marschalek, Rolf

    2015-01-01

    AF4/AFF1 and AF5/AFF4 are the molecular backbone to assemble “super-elongation complexes” (SECs) that have two main functions: (1) control of transcriptional elongation by recruiting the positive transcription elongation factor b (P-TEFb = CyclinT1/CDK9) that is usually stored in inhibitory 7SK RNPs; (2) binding of different histone methyltransferases, like DOT1L, NSD1 and CARM1. This way, transcribed genes obtain specific histone signatures (e.g. H3K79me2/3, H3K36me2) to generate a transcriptional memory system. Here we addressed several questions: how is P-TEFb recruited into SEC, how is the AF4 interactome composed, and what is the function of the naturally occuring AF4N protein variant which exhibits only the first 360 amino acids of the AF4 full-length protein. Noteworthy, shorter protein variants are a specific feature of all AFF protein family members. Here, we demonstrate that full-length AF4 and AF4N are both catalyzing the transition of P-TEFb from 7SK RNP to their N-terminal domain. We have also mapped the protein-protein interaction network within both complexes. In addition, we have first evidence that the AF4N protein also recruits TFIIH and the tumor suppressor MEN1. This indicate that AF4N may have additional functions in transcriptional initiation and in MEN1-dependend transcriptional processes. PMID:26171280

  10. Structure, phase transitions, and isotope effects in [(CH3)4N]2PuCl6

    SciTech Connect

    Wilson, Richard E.

    2015-11-02

    The single crystal X-ray diffraction structure of [(CH3)4N]2PuCl6 is presented for the first time, resolving long standing confusion and speculation regarding the structure of this compound in the literature. A temperature dependent study of this compound shows that the structure of [(CH3)4N]2PuCl6 undergoes no fewer than two phase transitions between 100 and 360 K. The phase of [(CH3)4N]2PuCl6 at room temperature is Fd-3c a = 26.012(3) Å. At 360 K, the structure is in space group Fm-3m with a = 13.088(1) Å. The plutonium octahedra and tetramethylammonium cations undergo a rotative displacement and the degree of rotation varies with temperature, giving rise to the phase transition from Fm-3m to Fd-3c as the crystal is cooled. Synthesis and structural studies of the deuterated salt [(CD3)4N]2PuCl6 suggest that there is an isotopic effect associated with this phase transition as revealed by a changing transition temperature in the deuterated versus protonated compound indicating that the donor-acceptor interactions between the tetramethylammonium cations and the hexachloroplutonate anions are driving the phase transformation.

  11. Metastatic Neuroblastoma Confined to Distant Lymph Nodes (stage 4N) Predicts Outcome in Patients With Stage 4 Disease: A Study From the International Neuroblastoma Risk Group Database

    PubMed Central

    Morgenstern, Daniel A.; London, Wendy B.; Stephens, Derek; Volchenboum, Samuel L.; Hero, Barbara; Di Cataldo, Andrea; Nakagawara, Akira; Shimada, Hiroyuki; Ambros, Peter F.; Matthay, Katherine K.; Cohn, Susan L.; Pearson, Andrew D.J.; Irwin, Meredith S.

    2014-01-01

    Purpose The presence of distant metastases is one of the most powerful predictors of outcome in patients with neuroblastoma. However, the pattern of metastatic spread is not incorporated into current risk stratification systems. Small case series have suggested that patients with neuroblastoma who have metastatic disease limited to distant lymph nodes (4N disease) may have improved outcomes. Patients and Methods We analyzed retrospective data from the International Neuroblastoma Risk Group database for patients diagnosed from 1990 to 2002. 4N patients were compared with the remaining stage 4 patients (non-4N), excluding those with missing metastatic site data. Results In all, 2,250 International Neuroblastoma Staging System stage 4 patients with complete data were identified, of whom 146 (6.5%) had 4N disease. For 4N patients, event-free survival (EFS; 5-year, 77% ± 4%) and overall survival (OS; 5-year, 85% ± 3%) were significantly better than EFS (5-year, 35% ± 1%) and OS (5-year, 42% ± 1%) for non-4N stage 4 patients (P < .001). 4N patients were more likely to be younger (P < .001) and have tumors with favorable characteristics, including absence of MYCN amplification (89% v 69%; P < .001). In a multivariable analysis, 4N disease remained a significant predictor of outcome (hazard ratio for non-4N v 4N: 3.40 for EFS and 3.69 for OS). Within subgroups defined by age at diagnosis and tumor MYCN status, 4N disease was significantly associated with improved outcomes. Conclusion 4N represents a subgroup with better outcome than that of other patients with metastatic disease. These findings suggest that the biology and treatment response of 4N tumors differ from other stage 4 tumors, and less intensive therapy should be considered for this cohort. Future exploration of biologic factors determining the pattern of metastatic spread is warranted. PMID:24663047

  12. Tetrabutylammonium cation in a homoleptic environment of borohydride ligands: [(n-Bu){sub 4}N][BH{sub 4}] and [(n-Bu){sub 4}N][Y(BH{sub 4}){sub 4}

    SciTech Connect

    Jaron, T.; Wegner, W.; Cyranski, M.K.; Dobrzycki, L.; Grochala, W.

    2012-07-15

    A novel solvent-free dual-cation organic-inorganic derivative, tetrabutylammonium yttrium borohydride (TBAYB), has been prepared for the first time and structurally characterized together with its organic precursor, tetrabutylammonium borohydride (TBAB). Both compounds crystallize in monoclinic unit cells (TBAYB: P2{sub 1}/c, TBAB: P2/c) and they contain [(n-Bu){sub 4}N]{sup +} in a homoleptic environment consisting of BH{sub 4}{sup -} ligands. Presence of large and lightweight Bu{sub 4}N{sup +} cations results in loose packing and low densities of both solids close to 1 g cm{sup -3}. TBAB melts at ca. 130 Degree-Sign C and it decomposes thermally above 160 Degree-Sign C while TBAYB melts at temperature as low as 78 Degree-Sign C, and the melt is stable over an appreciable temperature range of ca. 150 Degree-Sign C. The low melting point of TBAYB is the second lowest among derivatives of yttrium rendering this compound a new ionic liquid above 78 Degree-Sign C. - Graphical abstract: A novel organic-inorganic hybrid material for hydrogen storage, where (n-Bu){sub 4}N{sup +} cation is found in homoleptic environment of BH{sub 4}{sup -} ligands, was synthesised. Highlights: Black-Right-Pointing-Pointer Novel organic-inorganic hybrid material for hydrogen storage was synthesised. Black-Right-Pointing-Pointer (n-Bu){sub 4}N{sup +} cation is found in a homoleptic environment of BH{sub 4}{sup -} ligands. Black-Right-Pointing-Pointer TBAYB derivative is a novel ionic liquid with melting point of 78 Degree-Sign C..

  13. Using instability of nanometric liquid Cu films on SiO2 substrates to determine the underlying van der Waals potential

    NASA Astrophysics Data System (ADS)

    González, Alejandro G.; Diez, Javier A.; Wu, Yueying; Fowlkes, Jason D.; Rack, Philip D.; Kondic, Lou

    2013-11-01

    We study the instability of nanometric Cu thin films on a SiO2 substrate. The metal is melted by means of laser pulses for some tens of nanoseconds. The free surface destabilizes during the liquid lifetime, leading to the formation of holes at first and to metal drops on the substrate in later stages. By analyzing the Fourier transforms of the SEM images obtained during the metal film evolution, we determine the emerging length scales for both early and late stages of the instability development. The results are analyzed within the framework of a long-wave hydrodynamic model, which introduces van der Waals forces by means of disjoining and conjoining pressures. These forces are characterized by a pair of exponents for the ratio h / h * , where h is the liquid thickness and h* is a residual one. We find that the pair (3 , 2) provides a good agreement for the relationship of the wavelength with maximum growth rate, λm, while other typical pairs, such as (4 , 3) and (9 , 3) do not provide accurate description of the experimental data. Supported by CONICET-Argentina grant PIP 844/2011 (AGG, JAD), and by NSF grants CBET-1235651 (PDR) and CBET-1235710 (LK).

  14. Multicomponent High-Strength Low-Alloy Steel Precipitation-Strengthened by Sub-nanometric Cu Precipitates and M2C Carbides

    NASA Astrophysics Data System (ADS)

    Jain, Divya; Isheim, Dieter; Hunter, Allen H.; Seidman, David N.

    2016-08-01

    HSLA-115 is a novel high-strength low-alloy structural steel derived from martensitic Cu-bearing HSLA-100. HSLA-100 is typically used in conditions with overaged Cu precipitates, to obtain acceptable impact toughness and ductility. Present work on HSLA-115 demonstrates that incorporating sub-nanometric-sized M2C carbides along with Cu precipitates produces higher strength steels that still meet impact toughness and ductility requirements. Isothermal aging at 823 K (550 °C) precipitates M2C carbides co-located with the Cu precipitates and distributed heterogeneously at lath boundaries and dislocations. 3D atom-probe tomography is used to characterize the evolution of these precipitates at 823 K (550 °C) in terms of mean radii, number densities, and volume fractions. These results are correlated with microhardness, impact toughness, and tensile strength. The optimum combination of mechanical properties, 972 MPa yield strength, 24.8 pct elongation to failure, and 188.0 J impact toughness at 255 K (-18 °C), is attained after 3-hour aging at 823 K (550 °C). Strengthening by M2C precipitates offsets the softening due to overaging of Cu precipitates and tempering of martensitic matrix. It is shown that this extended yield strength plateau can be used as a design principle to optimize strength and toughness at the same time.

  15. Reversible Exsolution of Nanometric Fe2O3 Particles in BaFe2-x(PO4)2 (0 ≤ x ≤ 2/3):The Logic of Vacancy Ordering in Novel Metal-Depleted Two-Dimensional Lattices

    SciTech Connect

    Alcover, Ignacio Blazquez; David, Rénald; Daviero-Minaud, Sylvie; Filimonov, Dmitry; Huvé, Marielle; Roussel, Pascal; Kabbour, Houria; Mentré, Olivier

    2015-08-12

    We show here that the exsolution of Fe2+ ions out of two-dimensional (2D) honeycomb layers of BaFe2(PO4)2 into iron-deficient BaFe2–x(PO4)2 phases and nanometric α-Fe2O3 (typically 50 nm diameter at the grain surface) is efficient and reversible until x = 2/3 in mild oxidizing/reducing conditions. It corresponds to the renewable conversion of 12 wt % of the initial mass into iron oxide. After analyzing single crystal X-ray diffraction data of intermediate members x = 2/7, x = 1/3, x = 1/2 and the ultimate Fe-depleted x = 2/3 term, we then observed a systematic full ordering between Fe ions and vacancies (VFe) that denote unprecedented easy in-plane metal diffusion driven by the Fe2+/Fe3+ redox. Besides the discovery of a diversity of original depleted triangular {Fe2/3+2–xO6} topologies, we propose a unified model correlating the x Fe-removal and the experimental Fe/VFe ordering into periodic one-dimensional motifs paving the layers, gaining insights into predictive crystahemistry of complex low dimensional oxides. When we increased the x values it led to a progressive change of the materials from 2D ferromagnets (Fe2+) to 2D ferrimagnets (Fe2/3+) to antiferromagnets for x = 2/3 (Fe3+).

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

    PubMed Central

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

    2012-01-01

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

  17. Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn{sub 4}N epitaxial thin film

    SciTech Connect

    Shen, Xi; Shigematsu, Kei; Chikamatsu, Akira Fukumura, Tomoteru; Hirose, Yasushi; Hasegawa, Tetsuya

    2014-08-18

    We report the electrical transport properties of ferrimagnetic Mn{sub 4}N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn{sub 4}N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m{sup 3}, which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

  18. Solid-state photochemistry as a formation mechanism for Titan's stratospheric C4N2 ice clouds

    NASA Astrophysics Data System (ADS)

    Anderson, C. M.; Samuelson, R. E.; Yung, Y. L.; McLain, J. L.

    2016-04-01

    We propose that C4N2 ice clouds observed in Titan's springtime polar stratosphere arise due to solid-state photochemistry occurring within extant ice cloud particles of HCN-HC3N mixtures. This formation process resembles the halogen-induced ice particle surface chemistry that leads to condensed nitric acid trihydrate (NAT) particles and ozone depletion in Earth's polar stratosphere. As our analysis of the Cassini Composite Infrared Spectrometer 478 cm-1 ice emission feature demonstrates, this solid-state photochemistry mechanism eliminates the need for the relatively high C4N2 saturation vapor pressures required (even though they are not observed) when the ice is produced through the usual procedure of direct condensation from the vapor.

  19. The investigation of the electrical properties of Fe3O4/n-Si heterojunctions in a wide temperature range.

    PubMed

    Deniz, Ali Rıza; Çaldıran, Zakir; Metin, Önder; Meral, Kadem; Aydoğan, Şakir

    2016-07-01

    Monodisperse 8nm Fe3O4 nanoparticles (NPs) were synthesized by the thermal decomposition of iron(III) acetylacetonate in oleylamine and then were deposited onto n-type silicon wafer having the Al ohmic contact. Next, the morphology of the Fe3O4 NPs were characterized by using TEM and XRD. The optical properties of Fe3O4 NPs film was studied by UV-Vis spectroscopoy and its band gap was calculated to be 2.16eV. Au circle contacts with 7.85×10(-3)cm(2) area were provided on the Fe3O4 film via evaporation at 10(-5)Torr and the Au/Fe3O4 NPs/n-Si/Al heterojunction device were fabricated. The temperature-dependent junction parameters of Au/Fe3O4/n-Si/Al device including ideality factor, barrier height and series resistance were calculated by using the I-V characteristics in a wide temperature range of 40-300K. The results revealed that the ideality factor and series resistance increased by the decreasing temperature while the barrier height decreases. The Richardson constant of Au/Fe3O4/n-Si/Al device was calculated to be 2.17A/K(2)cm(2) from the I-V characteristics. The temperature dependence of Au/Fe3O4/n-Si/Al heterojunction device showed a double Gaussian distribution, which is caused by the inhomogeneities characteristics of Fe3O4/n-Si heterojunction.

  20. Spinel ZnCo2O4/N-doped carbon nanotube composite: A high active oxygen reduction reaction electrocatalyst

    NASA Astrophysics Data System (ADS)

    Pu, Zonghua; Liu, Qian; Tang, Chun; Asiri, Abdullah M.; Qusti, Abdullah H.; Al-Youbi, Abdulrahman O.; Sun, Xuping

    2014-07-01

    In this communication, we report on the solvothermal preparation of spinel ZnCo2O4/N-doped carbon nanotube (ZnCo2O4/NCNT) composite. As a novel oxygen reduction reaction (ORR) electrocatalyst, the ZnCo2O4/NCNT composite shows high activity via a four-electron pathway in alkaline solution. Such catalyst also exhibits superior methanol tolerance ability and durability over commercial Pt/C catalyst.

  1. DDX6 transfers P-TEFb kinase to the AF4/AF4N (AFF1) super elongation complex

    PubMed Central

    Mück, Fabian; Bracharz, Silvia; Marschalek, Rolf

    2016-01-01

    AF4/AFF1 and AF5/AFF4 are both backbones for the assembly of “super elongation complexes” (SECs) that exert 2 distinct functions after the recruitment of P-TEFb from the 7SK snRNP: (1) initiation and elongation of RNA polymerase II gene transcription, and (2) modification of transcribed gene regions by distinct histone methylation patterns. In this study we aimed to investigate one of the initial steps, namely how P-TEFb is transferred from 7SK snRNPs to the SECs. In particular, we were interested in the role of DDX6 that we have recently identified as part of the AF4 complex. DDX6 is an evolutionarily conserved member of the DEAD-box RNA helicase family that is known to control miRNA and mRNA biology (translation, storage and degradation). Overexpressed DDX6 is associated with different cancer types and with c-Myc protein overexpression. We could demonstrate that DDX6 binds to 7SK snRNA and causes the release and transfer of P-TEFb to the AF4/AF4N SEC. DDX6 also binds stably to AF4 and AF4N as demonstrated by GST pull-down and co-immunoprecipitation experiments. As a consequence, overexpression of either AF4/AF4N or DDX6 resulted in a strong increase of mRNA production (5-6 fold), while their simultaneous expression increased the cellular mRNA production by 11-fold. Conversely, the corresponding knockdown of DDX6 decreased mRNA production by 70%. In conclusion, AF4/AF4N and DDX6 represent key molecules for the elongation process of gene transcription and a model will be proposed for the hand-over process of P-TEFb to SECs. PMID:27679741

  2. Etch characteristics of magnetic tunnel junction materials using bias pulsing in the CH4/N2O inductively coupled plasma.

    PubMed

    Jeon, Min Hwan; Youn, Ji Youn; Yang, Kyung Chae; Yun, Deok Hyun; Lee, Du Yeong; Shim, Tae Hun; Park, Jea Gun; Yeom, Geun Young

    2014-12-01

    The etch characteristics of magnetic tunneling junction (MTJ) related materials such as CoFeB, MgO, FePt, Ru, and W as hard mask have been investigated as functions of rf pulse biasing, substrate heating, and CH4/N2O gas combination in an inductively coupled plasma system. When CH4/N2O gas ratio was varied, at CH4/N2O gas ratio of 2:1, not only the highest etch rates but also the highest etch selectivity over W could be obtained. By increasing the substrate temperature, the linear increase of both the etch rates of MTJ materials and the etch selectivity over W could be obtained. The use of the rf pulse biasing improved the etch selectivity of the MTJ materials over hard mask such as W further. The surface roughness and residual thickness remaining on the etched surface of the CoFeB were also decreased by using rf pulse biasing and with the decrease of rf duty percentage. The improvement of etch characteristics by substrate heating and rf pulse biasing was possibly related to the formation of more stable and volatile etch compounds and the removal of chemically reacted compounds more easily on the etched CoFeB surface. Highly selective etching of MTJ materials over the hard mask could be obtained by using the rf pulse biasing of 30% of duty ratio and by increasing the substrate temperature to 200 degrees C in the CH4/N2O (2:1) plasmas. PMID:25971096

  3. Stereotactic body radiotherapy for T3 and T4N0M0 non–small cell lung cancer

    PubMed Central

    Eriguchi, Takahisa; Takeda, Atsuya; Sanuki, Naoko; Nishimura, Shuichi; Takagawa, Yoshiaki; Enomoto, Tatsuji; Saeki, Noriyuki; Yashiro, Kae; Mizuno, Tomikazu; Aoki, Yousuke; Oku, Yohei; Yokosuka, Tetsuya; Shigematsu, Naoyuki

    2016-01-01

    To evaluate the outcomes and feasibility of stereotactic body radiotherapy (SBRT) for cT3 and cT4N0M0 non–small cell lung cancer (NSCLC), 25 patients with localized primary NSCLC diagnosed as cT3 or cT4N0M0, given SBRT between May 2005 and July 2013, were analyzed. All patients had inoperable tumors. The major reasons for tumors being unresectable were insufficient respiratory function for curative resection, advanced age (>80 years old) or technically inoperable due to invasion into critical organs. The median patient age was 79 years (range; 60–86). The median follow-up duration was 25 months (range: 5–100 months). The 2-year overall survival rates for T3 and T4 were 57% and 69%, respectively. The 2-year local control rates for T3 and T4 were 91% and 68%, respectively. As for toxicities, Grade 0–1, Grade 2 and Grade 3 radiation pneumonitis occurred in 23, 1 and 1 patient, respectively. No other acute or symptomatic late toxicities were reported. Thirteen patients who had no local, mediastinal or intrapulmonary progression at one year after SBRT underwent pulmonary function testing. The median variation in pre-SBRT and post-SBRT forced expiratory volume in 1 s (FEV1) values was –0.1 (–0.8–0.8). This variation was not statistically significant (P = 0.56). Forced vital capacity (FVC), vital capacity (VC), %VC and %FEV1 also showed no significant differences. SBRT for cT3 and cT4N0M0 NSCLC was both effective and feasible. Considering the favorable survival and low morbidity rate, SBRT is a potential treatment option for cT3 and cT4N0M0 NSCLC. PMID:26983978

  4. DDX6 transfers P-TEFb kinase to the AF4/AF4N (AFF1) super elongation complex.

    PubMed

    Mück, Fabian; Bracharz, Silvia; Marschalek, Rolf

    2016-01-01

    AF4/AFF1 and AF5/AFF4 are both backbones for the assembly of "super elongation complexes" (SECs) that exert 2 distinct functions after the recruitment of P-TEFb from the 7SK snRNP: (1) initiation and elongation of RNA polymerase II gene transcription, and (2) modification of transcribed gene regions by distinct histone methylation patterns. In this study we aimed to investigate one of the initial steps, namely how P-TEFb is transferred from 7SK snRNPs to the SECs. In particular, we were interested in the role of DDX6 that we have recently identified as part of the AF4 complex. DDX6 is an evolutionarily conserved member of the DEAD-box RNA helicase family that is known to control miRNA and mRNA biology (translation, storage and degradation). Overexpressed DDX6 is associated with different cancer types and with c-Myc protein overexpression. We could demonstrate that DDX6 binds to 7SK snRNA and causes the release and transfer of P-TEFb to the AF4/AF4N SEC. DDX6 also binds stably to AF4 and AF4N as demonstrated by GST pull-down and co-immunoprecipitation experiments. As a consequence, overexpression of either AF4/AF4N or DDX6 resulted in a strong increase of mRNA production (5-6 fold), while their simultaneous expression increased the cellular mRNA production by 11-fold. Conversely, the corresponding knockdown of DDX6 decreased mRNA production by 70%. In conclusion, AF4/AF4N and DDX6 represent key molecules for the elongation process of gene transcription and a model will be proposed for the hand-over process of P-TEFb to SECs. PMID:27679741

  5. Growth and electrical properties on NLO crystal: 4-N,N-dimethylamino 4′-N′-methylstilbazolium iodide

    SciTech Connect

    Kumar, M. Krishna Sudhahar, S. Kumar, R. Mohan

    2014-04-24

    4-N,N-Dimethylamino-4′-N′-methylstilbazolium tosylate single crystals were grown by solution crystal growth method. The cell parameters of grown crystal have been estimated using single crystal-X-ray diffraction analysis. The variation of real (´ε) and imaginary (´ε) part of dielectric constants and dielectric loss were observed for different frequencies and temperatures. The ac and dc electrical conductivities and activation energy were determined for DMSI crystal using dielectric studies.

  6. Stereotactic body radiotherapy for T3 and T4N0M0 non-small cell lung cancer.

    PubMed

    Eriguchi, Takahisa; Takeda, Atsuya; Sanuki, Naoko; Nishimura, Shuichi; Takagawa, Yoshiaki; Enomoto, Tatsuji; Saeki, Noriyuki; Yashiro, Kae; Mizuno, Tomikazu; Aoki, Yousuke; Oku, Yohei; Yokosuka, Tetsuya; Shigematsu, Naoyuki

    2016-06-01

    To evaluate the outcomes and feasibility of stereotactic body radiotherapy (SBRT) for cT3 and cT4N0M0 non-small cell lung cancer (NSCLC), 25 patients with localized primary NSCLC diagnosed as cT3 or cT4N0M0, given SBRT between May 2005 and July 2013, were analyzed. All patients had inoperable tumors. The major reasons for tumors being unresectable were insufficient respiratory function for curative resection, advanced age (>80 years old) or technically inoperable due to invasion into critical organs. The median patient age was 79 years (range; 60-86). The median follow-up duration was 25 months (range: 5-100 months). The 2-year overall survival rates for T3 and T4 were 57% and 69%, respectively. The 2-year local control rates for T3 and T4 were 91% and 68%, respectively. As for toxicities, Grade 0-1, Grade 2 and Grade 3 radiation pneumonitis occurred in 23, 1 and 1 patient, respectively. No other acute or symptomatic late toxicities were reported. Thirteen patients who had no local, mediastinal or intrapulmonary progression at one year after SBRT underwent pulmonary function testing. The median variation in pre-SBRT and post-SBRT forced expiratory volume in 1 s (FEV1) values was -0.1 (-0.8-0.8). This variation was not statistically significant (P = 0.56). Forced vital capacity (FVC), vital capacity (VC), %VC and %FEV1 also showed no significant differences. SBRT for cT3 and cT4N0M0 NSCLC was both effective and feasible. Considering the favorable survival and low morbidity rate, SBRT is a potential treatment option for cT3 and cT4N0M0 NSCLC. PMID:26983978

  7. DDX6 transfers P-TEFb kinase to the AF4/AF4N (AFF1) super elongation complex

    PubMed Central

    Mück, Fabian; Bracharz, Silvia; Marschalek, Rolf

    2016-01-01

    AF4/AFF1 and AF5/AFF4 are both backbones for the assembly of “super elongation complexes” (SECs) that exert 2 distinct functions after the recruitment of P-TEFb from the 7SK snRNP: (1) initiation and elongation of RNA polymerase II gene transcription, and (2) modification of transcribed gene regions by distinct histone methylation patterns. In this study we aimed to investigate one of the initial steps, namely how P-TEFb is transferred from 7SK snRNPs to the SECs. In particular, we were interested in the role of DDX6 that we have recently identified as part of the AF4 complex. DDX6 is an evolutionarily conserved member of the DEAD-box RNA helicase family that is known to control miRNA and mRNA biology (translation, storage and degradation). Overexpressed DDX6 is associated with different cancer types and with c-Myc protein overexpression. We could demonstrate that DDX6 binds to 7SK snRNA and causes the release and transfer of P-TEFb to the AF4/AF4N SEC. DDX6 also binds stably to AF4 and AF4N as demonstrated by GST pull-down and co-immunoprecipitation experiments. As a consequence, overexpression of either AF4/AF4N or DDX6 resulted in a strong increase of mRNA production (5-6 fold), while their simultaneous expression increased the cellular mRNA production by 11-fold. Conversely, the corresponding knockdown of DDX6 decreased mRNA production by 70%. In conclusion, AF4/AF4N and DDX6 represent key molecules for the elongation process of gene transcription and a model will be proposed for the hand-over process of P-TEFb to SECs.

  8. The first quaternary lanthanide(III) nitride iodides: Na M4N 2I 7 ( M=La-Nd)

    NASA Astrophysics Data System (ADS)

    Schurz, Christian M.; Schleid, Thomas

    2010-10-01

    In attempts to synthesize lanthanide(III) nitride iodides with the formula M2NI 3 ( M=La-Nd), moisture-sensitive single crystals of the first quaternary sodium lanthanide(III) nitride iodides Na M4N 2I 7 (orthorhombic, Pna2 1; Z=4; a=1391-1401, b=1086-1094, c=1186-1211 pm) could be obtained. The dominating structural features are {[}∞1 chains of trans-edge linked [N M4] 9+ tetrahedra, which run parallel to the polar 2 1-axis [001]. Between the chains, direct bonding via special iodide anions generates cages, in which isolated [NaI 6] 5- octahedra are embedded. The IR spectrum of NaLa 4N 2I 7 recorded from 100 to 1000 cm -1 shows main bands at υ=337, 373 and 489 cm -1. With decreasing radii of the lanthanide trications these bands, which can be assigned as an influence of the vibrations of the condensed [N M4] 9+ tetrahedra, are shifted toward higher frequencies for the Na M4N 2I 7 series ( M=La-Nd), following the lanthanide contraction.

  9. Characterization of an H4N2 Influenza Virus from Quails with a Multibasic Motif in the Hemagglutinin Cleavage Site

    PubMed Central

    Wong, Sook-San; Yoon, Sun-Woo; Zanin, Mark; Song, Min-Suk; Oshansky, Christine; Zaraket, Hassan; Sonnberg, Stephanie; Rubrum, Adam; Seiler, Patrick; Ferguson, Angela; Krauss, Scott; Cardona, Carol; Webby, Richard J.; Crossley, Beate

    2014-01-01

    The cleavage motif in the hemagglutinin (HA) protein of highly pathogenic H5 and H7 subtypes of avian influenza viruses is characterized by a peptide insertion or a multibasic cleavage site (MBCS). Here, we isolated an H4N2 virus from quails (Quail/CA12) with two additional arginines in the HA cleavage site, PEKRRTR/G, forming an MBCS-like motif. Quail/CA12 is a reassortant virus with the HA and neuraminidase (NA) gene most similar to a duck-isolated H4N2 virus, PD/CA06 with a monobasic HA cleavage site. Quail/CA12 required exogenous trypsin for efficient growth in culture and caused no clinical illness in infected chickens. Quail/CA12 had high binding preference for α2,6-linked sialic acids and showed higher replication and transmission ability in chickens and quails than PD/CA06. Although the H4N2 virus remained low pathogenic, these data suggests that the acquisition of MBCS in the field is not restricted to H5 or H7 subtypes. PMID:25151061

  10. Master curve characterization of the fracture toughness behavior in SA508 Gr.4N low alloy steels

    NASA Astrophysics Data System (ADS)

    Lee, Ki-Hyoung; Kim, Min-Chul; Lee, Bong-Sang; Wee, Dang-Moon

    2010-08-01

    The fracture toughness properties of the tempered martensitic SA508 Gr.4N Ni-Mo-Cr low alloy steel for reactor pressure vessels were investigated by using the master curve concept. These results were compared to those of the bainitic SA508 Gr.3 Mn-Mo-Ni low alloy steel, which is a commercial RPV material. The fracture toughness tests were conducted by 3-point bending with pre-cracked charpy (PCVN) specimens according to the ASTM E1921-09c standard method. The temperature dependency of the fracture toughness was steeper than those predicted by the standard master curve, while the bainitic SA508 Gr.3 steel fitted well with the standard prediction. In order to properly evaluate the fracture toughness of the Gr.4N steels, the exponential coefficient of the master curve equation was changed and the modified curve was applied to the fracture toughness test results of model alloys that have various chemical compositions. It was found that the modified curve provided a better description for the overall fracture toughness behavior and adequate T0 determination for the tempered martensitic SA508 Gr.4N steels.

  11. Towards the development of multifunctional chitosan-based iron oxide nanoparticles: Optimization and modelling of doxorubicin release.

    PubMed

    Soares, Paula I P; Sousa, Ana Isabel; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-11-20

    In the present work composite nanoparticles with a magnetic core and a chitosan-based shell were produced as drug delivery systems for doxorubicin (DOX). The results show that composite nanoparticles with a hydrodynamic diameter within the nanometric range are able to encapsulate more DOX than polymeric nanoparticles alone corresponding also to a higher drug release. Moreover the synthesis method of the iron oxide nanoparticles influences the total amount of DOX released and a high content of iron oxide nanoparticles inhibits DOX release. The modelling of the experimental results revealed a release mechanism dominated by Fickian diffusion. PMID:27561489

  12. Towards the development of multifunctional chitosan-based iron oxide nanoparticles: Optimization and modelling of doxorubicin release.

    PubMed

    Soares, Paula I P; Sousa, Ana Isabel; Ferreira, Isabel M M; Novo, Carlos M M; Borges, João Paulo

    2016-11-20

    In the present work composite nanoparticles with a magnetic core and a chitosan-based shell were produced as drug delivery systems for doxorubicin (DOX). The results show that composite nanoparticles with a hydrodynamic diameter within the nanometric range are able to encapsulate more DOX than polymeric nanoparticles alone corresponding also to a higher drug release. Moreover the synthesis method of the iron oxide nanoparticles influences the total amount of DOX released and a high content of iron oxide nanoparticles inhibits DOX release. The modelling of the experimental results revealed a release mechanism dominated by Fickian diffusion.

  13. A novel one-step strategy toward ZnMn2O4/N-doped graphene nanosheets with robust chemical interaction for superior lithium storage.

    PubMed

    Wang, Dong; Zhou, Weiwei; Zhang, Yong; Wang, Yali; Wu, Gangan; Yu, Kun; Wen, Guangwu

    2016-01-29

    Ingenious hybrid electrode design, especially realized with a facile strategy, is appealing yet challenging for electrochemical energy storage devices. Here, we report the synthesis of a novel ZnMn2O4/N-doped graphene (ZMO/NG) nanohybrid with sandwiched structure via a facile one-step approach, in which ultrafine ZMO nanoparticles with diameters of 10-12 nm are well dispersed on both surfaces of N-doped graphene (NG) nanosheets. Note that one-step synthetic strategies are rarely reported for ZMO-based nanostructures. Systematical control experiments reveal that the formation of well-dispersed ZMO nanoparticles is not solely ascribed to the restriction effect of the functional groups on graphene oxide (GO), but also to the presence of ammonia. Benefitting from the synergistic effects and robust chemical interaction between ZMO nanoparticles and N-doped graphene nanosheets, the ZMO/NG hybrids deliver a reversible capacity up to 747 mAh g(-1) after 200 cycles at a current density of 500 mA g(-1). Even at a high current density of 3200 mA g(-1), an unrivaled capacity of 500 mAh g(-1) can still be retained, corroborating the good rate capability.

  14. Conversion of 4-N,N-dimethylamino-4’-N’-methyl-stilbazolium tosylate (DAST) from a Simple Optical Material to a Versatile Optoelectronic Material

    PubMed Central

    Xu, Xiangdong; Sun, Ziqiang; Fan, Kai; Jiang, Yadong; Huang, Rui; Wen, Yuejiang; He, Qiong; Ao, Tianhong

    2015-01-01

    4-N,N-dimethylamino-4’-N’-methyl-stilbazolium tosylate (DAST) is an important optical material, but its poor conductivity limits applications in devices. To tackle this problem, we designed, prepared, and systematically investigated novel binary composite films that are composed of two-dimensional (2D) DAST and 2D graphene. Results indicate that both electrical and optical properties of DAST can be significantly improved by graphene addition. The negative steric effects of big DAST molecules that greatly trouble ex-situ synthesis can be efficiently overcome by in-situ synthesis, thus leading to better film quality and higher physical properties. Consequently, the in-situ composite film exhibits a low sheet resistance of 7.5 × 106 ohm and high temperature coefficient of resistance of −2.79% K−1, close to the levels of the most important bolometric materials for uncooled infrared detectors. Particularly, a new low temperature reduction of graphene oxide induced by DAST, which is further enhanced by in-situ process, was discovered. This work presents valuable information about the DAST–graphene composite films, their chemical structures, mechanisms, physical properties, and comparison on in-situ and ex-situ syntheses of graphene–based composites, all of which will be helpful for not only theoretically studying the DAST and graphene materials and expanding their applications, but also for seeking new optoelectronic sensitive materials. PMID:26192068

  15. Macrocyclic Se4N2[7,7]ferrocenophane and Se2N[10]ferrocenophane containing benzyl unit: synthesis, complexation, crystal structures, electrochemical and optical properties.

    PubMed

    Qu, Jian; Song, Yinglin; Ji, Wei; Jing, Su; Zhu, Dunru; Huang, Wei; Zheng, Mengxi; Li, Yanle; Ma, Jing

    2016-02-28

    Two novel macrocyclic polyselena[n]ferrocenophanes containing a pendent benzyl unit, 20-membered Se4N2[7,7]ferrocenophane (L1) and 10-membered Se2N[10]ferrocenophane (L2), were designed and synthesized. The reaction of L1 with two molar amounts of metal salts (M = Cu(+), Cu(2+), Pd(2+) and Hg(2+)) led to six dimetallic complexes 1-6. A crystallographic study revealed that each metal center in 1-5 was tetracoordinated to two selenium atoms from different ferrocene units, one aliphatic nitrogen atom and one co-ligand. The structures of the complexes contain a two-fold axis perpendicular to the molecular plane with two pendant benzyl moieties in an anti-conformation. Macrocycle L1 gives significant electrochemical, linear and third-order nonlinear optical responses to Cu(2+) and Hg(2+). The DFT/B3LYP calculations of 4 demonstrated a small HOMO-LUMO energy gap and delocalization of the π-electron cloud in the frontier molecular orbitals, which led to the enhancement of molecular NLO properties after complexation. The results show that the oxidation state of the ferrocene unit is accompanied by significant differences in the corresponding absorption spectra and third-order NLO properties. PMID:26790582

  16. A novel one-step strategy toward ZnMn2O4/N-doped graphene nanosheets with robust chemical interaction for superior lithium storage

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Zhou, Weiwei; Zhang, Yong; Wang, Yali; Wu, Gangan; Yu, Kun; Wen, Guangwu

    2016-01-01

    Ingenious hybrid electrode design, especially realized with a facile strategy, is appealing yet challenging for electrochemical energy storage devices. Here, we report the synthesis of a novel ZnMn2O4/N-doped graphene (ZMO/NG) nanohybrid with sandwiched structure via a facile one-step approach, in which ultrafine ZMO nanoparticles with diameters of 10-12 nm are well dispersed on both surfaces of N-doped graphene (NG) nanosheets. Note that one-step synthetic strategies are rarely reported for ZMO-based nanostructures. Systematical control experiments reveal that the formation of well-dispersed ZMO nanoparticles is not solely ascribed to the restriction effect of the functional groups on graphene oxide (GO), but also to the presence of ammonia. Benefitting from the synergistic effects and robust chemical interaction between ZMO nanoparticles and N-doped graphene nanosheets, the ZMO/NG hybrids deliver a reversible capacity up to 747 mAh g-1 after 200 cycles at a current density of 500 mA g-1. Even at a high current density of 3200 mA g-1, an unrivaled capacity of 500 mAh g-1 can still be retained, corroborating the good rate capability.

  17. Highly efficient and ultra-broadband graphene oxide ultrathin lenses with three-dimensional subwavelength focusing

    PubMed Central

    Zheng, Xiaorui; Jia, Baohua; Lin, Han; Qiu, Ling; Li, Dan; Gu, Min

    2015-01-01

    Nanometric flat lenses with three-dimensional subwavelength focusing are indispensable in miniaturized optical systems. However, they are fundamentally challenging to achieve because of the difficulties in accurately controlling the optical wavefront by a film with nanometric thickness. Based on the unique and giant refractive index and absorption modulations of the sprayable graphene oxide thin film during its laser reduction process, we demonstrate a graphene oxide ultrathin (∼200 nm) flat lens that shows far-field three-dimensional subwavelength focusing (λ3/5) with an absolute focusing efficiency of >32% for a broad wavelength range from 400 to 1,500 nm. Our flexible graphene oxide lenses are mechanically robust and maintain excellent focusing properties under high stress. The simple and scalable fabrication approach enables wide potential applications in on-chip nanophotonics. The wavefront shaping concept opens up new avenues for easily accessible, highly precise and efficient optical beam manipulations with a flexible and integratable planar graphene oxide ultrathin film. PMID:26391504

  18. Highly efficient and ultra-broadband graphene oxide ultrathin lenses with three-dimensional subwavelength focusing.

    PubMed

    Zheng, Xiaorui; Jia, Baohua; Lin, Han; Qiu, Ling; Li, Dan; Gu, Min

    2015-01-01

    Nanometric flat lenses with three-dimensional subwavelength focusing are indispensable in miniaturized optical systems. However, they are fundamentally challenging to achieve because of the difficulties in accurately controlling the optical wavefront by a film with nanometric thickness. Based on the unique and giant refractive index and absorption modulations of the sprayable graphene oxide thin film during its laser reduction process, we demonstrate a graphene oxide ultrathin (∼200 nm) flat lens that shows far-field three-dimensional subwavelength focusing (λ(3)/5) with an absolute focusing efficiency of >32% for a broad wavelength range from 400 to 1,500 nm. Our flexible graphene oxide lenses are mechanically robust and maintain excellent focusing properties under high stress. The simple and scalable fabrication approach enables wide potential applications in on-chip nanophotonics. The wavefront shaping concept opens up new avenues for easily accessible, highly precise and efficient optical beam manipulations with a flexible and integratable planar graphene oxide ultrathin film. PMID:26391504

  19. Ordered fragmentation of oxide thin films at submicron scale

    PubMed Central

    Guo, L.; Ren, Y.; Kong, L. Y.; Chim, W. K.; Chiam, S. Y.

    2016-01-01

    Crack formation is typically undesirable as it represents mechanical failure that compromises strength and integrity. Recently, there have also been numerous attempts to control crack formation in materials with the aim to prevent or isolate crack propagation. In this work, we utilize fragmentation, at submicron and nanometre scales, to create ordered metal oxide film coatings. We introduce a simple method to create modified films using electroplating on a prepatterned substrate. The modified films undergo preferential fragmentation at locations defined by the initial structures on the substrate, yielding ordered structures. In thicker films, some randomness in the characteristic sizes of the fragments is introduced due to competition between crack propagation and crack creation. The method presented allows patterning of metal oxide films over relatively large areas by controlling the fragmentation process. We demonstrate use of the method to fabricate high-performance electrochromic structures, yielding good coloration contrast and high coloration efficiency. PMID:27748456

  20. Ordered fragmentation of oxide thin films at submicron scale

    NASA Astrophysics Data System (ADS)

    Guo, L.; Ren, Y.; Kong, L. Y.; Chim, W. K.; Chiam, S. Y.

    2016-10-01

    Crack formation is typically undesirable as it represents mechanical failure that compromises strength and integrity. Recently, there have also been numerous attempts to control crack formation in materials with the aim to prevent or isolate crack propagation. In this work, we utilize fragmentation, at submicron and nanometre scales, to create ordered metal oxide film coatings. We introduce a simple method to create modified films using electroplating on a prepatterned substrate. The modified films undergo preferential fragmentation at locations defined by the initial structures on the substrate, yielding ordered structures. In thicker films, some randomness in the characteristic sizes of the fragments is introduced due to competition between crack propagation and crack creation. The method presented allows patterning of metal oxide films over relatively large areas by controlling the fragmentation process. We demonstrate use of the method to fabricate high-performance electrochromic structures, yielding good coloration contrast and high coloration efficiency.

  1. Ferromagnet / superconductor oxide superlattices

    NASA Astrophysics Data System (ADS)

    Santamaria, Jacobo

    2006-03-01

    The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peña^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic

  2. Electron attachment and detachment, and the electron affinities of C5F5N and C5HF4N.

    PubMed

    Van Doren, Jane M; Kerr, Donna M; Miller, Thomas M; Viggiano, A A

    2005-09-15

    Rate constants have been measured for electron attachment to C5F5N (297-433 K) and to 2, 3, 5, 6-C5HF4N (303 K) using a flowing-afterglow Langmuir-probe apparatus (at a He gas pressure of 133 Pa). In both cases only the parent anion was formed in the attachment process. The attachment rate constants measured at room temperature are 1.8 +/- 0.5 X 10(-7) and 7 +/- 3 X 10(-10) cm(-3) s(-1), respectively. Rate constants were also measured for thermal electron detachment from the parent anions of these molecules. For C5F5N- detachment is negligible at room temperature, but increases to 2530 +/- 890 s(-1) at 433 K. For 2, 3, 5, 6-C5HF4N-, the detachment rate at 303 K was 520 +/- 180 s(-1). The attachment/detachment equilibrium yielded experimental electron affinities EA(C5F5N)=0.70 +/- 0.05 eV and EA(2, 3, 5, 6-C5HF4N)=0.40 +/- 0.08 eV. Electronic structure calculations were carried out for these molecules and related C5HxF5-xN using density-functional theory and the G3(MP2)//B3LYP compound method. The EAs are found to decrease by 0.25 eV, on average, with each F substitution by H. The calculated EAs are in good agreement with the present experimental results.

  3. Optical properties of zirconia doped with yttria and some rare earth oxides

    NASA Astrophysics Data System (ADS)

    Haberko, Jakub; Trenczek-Zając, Anita; Zientara, Dariusz; Adamczyk, Anna; Haberko, Krzysztof; Bućko, Mirosław M.

    2016-10-01

    Nanometric powders of cubic zirconia stabilized with yttria and rare element oxides (Sm, Nd, Gd) were prepared by crystallization under hydrothermal conditions. The powders were uniaxially compacted, repressed isostatically, pressure-less sintered in oxygen atmosphere and hot isostatically pressed under 300 MPa Ar atmosphere. Fully dense samples were polished from both sides. The optical properties were analyzed based on the spectral dependence of the transmittance (T) and reflectance (R). Spectroscopic measurements have shown that all materials fabricated in the present work are highly transparent, with total transmission above 90% towards the long-wavelength end of the near-IR range of the spectrum. Discussion of these results will be given.

  4. Electronic structure and pair potential energy analysis of 4-n-methoxy-4'-cyanobiphenyl: A nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Sharma, Dipendra; Dwivedi, M. K.; Tiwari, S. N.

    2016-05-01

    Electronic structure properties of 4-n-methoxy-4'-cyanobiphenyl, a pure nematic liquid crystal have been examined using an ab‒initio, HF/6‒31G(d,p) technique with GAMESS program. Conformational and charge distribution analysis have been carried out. MEP, HOMO and LUMO surfaces have been scanned. Ionization potential, electron affinity, electronegativity, global hardness and softness of the liquid crystal molecule have been calculated. Further, stacking, side by side and end to end interactions between a molecular pair have been evaluated. Results have been used to elucidate the physico-chemical and liquid crystalline properties of the system.

  5. Molecular characterization of an influenza A virus (H4N2) isolated from waterfowl habitats in the State of Mexico.

    PubMed

    Ornelas-Eusebio, Erika; Obregón-Ascencio, Alejandro; Chávez-Maya, Fernando; García-Espinosa, Gary

    2015-03-01

    Wild waterfowl and their habitats are the main reservoirs of influenza A virus (IAV) mainly during the breeding season and prior to migration. This study describes the molecular characterization of an IAV isolated from 240 water samples of a small wetland during non-breeding season of migratory wild ducks in the State of Mexico, Mexico. The results showed that the virus belongs to the H4N2 subtype and each of its eight segments of the viral genome has similarity to IAV isolated from ducks in North America. This study suggests that IAV can be isolated from small wetland during non-breeding season of migrating waterfowl. PMID:25482497

  6. Molecular characterization of an influenza A virus (H4N2) isolated from waterfowl habitats in the State of Mexico.

    PubMed

    Ornelas-Eusebio, Erika; Obregón-Ascencio, Alejandro; Chávez-Maya, Fernando; García-Espinosa, Gary

    2015-03-01

    Wild waterfowl and their habitats are the main reservoirs of influenza A virus (IAV) mainly during the breeding season and prior to migration. This study describes the molecular characterization of an IAV isolated from 240 water samples of a small wetland during non-breeding season of migratory wild ducks in the State of Mexico, Mexico. The results showed that the virus belongs to the H4N2 subtype and each of its eight segments of the viral genome has similarity to IAV isolated from ducks in North America. This study suggests that IAV can be isolated from small wetland during non-breeding season of migrating waterfowl.

  7. Molecular characterization of an influenza A virus (H4N2) isolated from waterfowl habitats in the State of Mexico

    PubMed Central

    ORNELAS-EUSEBIO, Erika; OBREGÓN-ASCENCIO, Alejandro; CHÁVEZ-MAYA, Fernando; GARCÍA-ESPINOSA, Gary

    2014-01-01

    Wild waterfowl and their habitats are the main reservoirs of influenza A virus (IAV) mainly during the breeding season and prior to migration. This study describes the molecular characterization of an IAV isolated from 240 water samples of a small wetland during non-breeding season of migratory wild ducks in the State of Mexico, Mexico. The results showed that the virus belongs to the H4N2 subtype and each of its eight segments of the viral genome has similarity to IAV isolated from ducks in North America. This study suggests that IAV can be isolated from small wetland during non-breeding season of migrating waterfowl. PMID:25482497

  8. catena-Poly[[aqua-{4-[N'-(2,4-dioxo-3-pentyl-idene)-hydrazino]-benzoato}-copper(II)]-μ-acetato].

    PubMed

    Hao, Lujiang; Mu, Chunhua; Wang, Ridong

    2008-01-01

    In the title compound, [Cu(CH(3)CO(2))(C(12)H(11)N(2)O(4))(H(2)O)](n), the Cu(II) cation is tetra-coordinated by three carboxyl-ate O atoms from one 4-[N'-(2,4-dioxo-3-pentyl-idene)-hydrazino]-benzoate ligand and two acetate bridges, and by one water mol-ecule. The acetate bridges link adjacent Cu(II) cations, forming a chain. The crystal structure involves O-H⋯O hydrogen bonds. PMID:21202784

  9. Microwave assisted synthesis of copper oxide and its application in electrochemical sensing

    NASA Astrophysics Data System (ADS)

    Felix, S.; Bala Praveen Chakkravarthy, R.; Nirmala Grace, A.

    2015-02-01

    Copper oxide nanopowders were prepared using copper acetate as the precursor and polyethylene glycol (PEG) as stabilizer in ethanol medium. The mixture containing copper acetate, sodium hydroxide and PEG was irradiated with microwave and nanometric copper oxide particles were formed within 8 min. The prepared nanoparticles were characterized using x-ray diffraction, UV-vis spectroscopy and scanning electron microscopy. The average particle size was found to be ~ 4 nm. This was used to modify glassy carbon electrode with PVDF & DMF as binder and used for sensing of carbohydrates (glucose and sucrose) and H2O2. The copper oxide nanoparticles showed excellent sensitivity in the range of 0.1 mM to 1 mM when choronoamperometry was carried out at 0.6 V Vs. Ag/AgCl. The observed sensitivity is much higher when compared with conventional micron sized copper oxide particles.

  10. The mitigating effect of calcification-dependent of utilization of inorganic carbon of Chara vulgaris Linn on NH4-N toxicity.

    PubMed

    Wang, Heyun; Ni, Leyi; Xie, Ping

    2013-09-01

    Increased ammonium (NH4-N) concentrations in water bodies have been reported to adversely affect the dominant species of submersed vegetation in meso-eutrophic waters worldwide. However calcareous plants were lowly sensitive to NH4-N toxicity. In order to make clear the function of calcification in the tolerance of calcareous plants to NH4-N stress, we studied the effects of increased HCO3(-) and additional NH4-N on calcification and utilization of dissolve inorganic carbon (DIC) in Chara vulgaris Linn in a 7-d sub-acute experiment (light:dark 12:12h) carried out in an open experimental system in lab. Results revealed that calcification was dependent of utilization of dissolve inorganic carbon. Additional HCO3(-) significantly decreased the increase of pH while additional NH4-N did not. And additional HCO3(-) significantly improved calcification while NH4-N did in versus in relation to the variation of DIC concentration. However, addition of both HCO3(-) and NH4-N increased utilization of DIC. This resulted in calcification to utilization of DIC ratio decreased under additional NH4-N condition while increased under additional HCO3(-) conditions in response to the variation of solution pH. In the present study, external HCO3(-) decreased the increase of solution pH by increasing calcification, which correspondingly mitigated the toxic effect of high NH4-N. And we argue that the mitigating effect of increased HCO3(-) on NH4-N toxicity is dependent of plant calcification, and it is a positive feedback mechanism, potentially leading to the dominance of calcareous plants in meso-eutrophic water bodies.

  11. The mitigating effect of calcification-dependent of utilization of inorganic carbon of Chara vulgaris Linn on NH4-N toxicity.

    PubMed

    Wang, Heyun; Ni, Leyi; Xie, Ping

    2013-09-01

    Increased ammonium (NH4-N) concentrations in water bodies have been reported to adversely affect the dominant species of submersed vegetation in meso-eutrophic waters worldwide. However calcareous plants were lowly sensitive to NH4-N toxicity. In order to make clear the function of calcification in the tolerance of calcareous plants to NH4-N stress, we studied the effects of increased HCO3(-) and additional NH4-N on calcification and utilization of dissolve inorganic carbon (DIC) in Chara vulgaris Linn in a 7-d sub-acute experiment (light:dark 12:12h) carried out in an open experimental system in lab. Results revealed that calcification was dependent of utilization of dissolve inorganic carbon. Additional HCO3(-) significantly decreased the increase of pH while additional NH4-N did not. And additional HCO3(-) significantly improved calcification while NH4-N did in versus in relation to the variation of DIC concentration. However, addition of both HCO3(-) and NH4-N increased utilization of DIC. This resulted in calcification to utilization of DIC ratio decreased under additional NH4-N condition while increased under additional HCO3(-) conditions in response to the variation of solution pH. In the present study, external HCO3(-) decreased the increase of solution pH by increasing calcification, which correspondingly mitigated the toxic effect of high NH4-N. And we argue that the mitigating effect of increased HCO3(-) on NH4-N toxicity is dependent of plant calcification, and it is a positive feedback mechanism, potentially leading to the dominance of calcareous plants in meso-eutrophic water bodies. PMID:23755986

  12. Determining a Structural Distortion and Anion Ordering in La2Si4N6C via Computation and Experiment.

    PubMed

    Hermus, Martin; Mansouri Tehrani, Aria; Brgoch, Jakoah

    2016-09-19

    A structural instability in the orthorhombic carbonitridosilicate La2Si4N6C arises when calculating the ab initio phonon dispersion curves. The presence of imaginary modes indicates the compound reported in space group Pnma is dynamically unstable with the eigenvectors showing a monoclinic distortion pathway leading to space group P21/c. Synthesizing La2Si4N6C using a high-temperature route and conducting a co-refinement with high-resolution synchrotron X-ray and neutron powder diffraction shows the predicted peak splitting confirming the predicted lower symmetry crystal structure. Further, the combination of ab initio computation, neutron diffraction, and a total scattering analysis based on a neutron pair distribution function analysis supports that the anions are fully ordered and that carbon is only found on the central position of a star-shaped C(SiN3)4 unit. These results illustrate the power of combining computation and experiment to unequivocally solve crystal structures from polycrystalline powders.

  13. DNA replication checkpoint signaling depends on a Rad53-Dbf4 N-terminal interaction in Saccharomyces cerevisiae.

    PubMed

    Chen, Ying-Chou; Kenworthy, Jessica; Gabrielse, Carrie; Hänni, Christine; Zegerman, Philip; Weinreich, Michael

    2013-06-01

    Dbf4-dependent kinase (DDK) and cyclin-dependent kinase (CDK) are essential to initiate DNA replication at individual origins. During replication stress, the S-phase checkpoint inhibits the DDK- and CDK-dependent activation of late replication origins. Rad53 kinase is a central effector of the replication checkpoint and both binds to and phosphorylates Dbf4 to prevent late-origin firing. The molecular basis for the Rad53-Dbf4 physical interaction is not clear but occurs through the Dbf4 N terminus. Here we found that both Rad53 FHA1 and FHA2 domains, which specifically recognize phospho-threonine (pT), interacted with Dbf4 through an N-terminal sequence and an adjacent BRCT domain. Purified Rad53 FHA1 domain (but not FHA2) bound to a pT Dbf4 peptide in vitro, suggesting a possible phospho-threonine-dependent interaction between FHA1 and Dbf4. The Dbf4-Rad53 interaction is governed by multiple contacts that are separable from the Cdc5- and Msa1-binding sites in the Dbf4 N terminus. Importantly, abrogation of the Rad53-Dbf4 physical interaction blocked Dbf4 phosphorylation and allowed late-origin firing during replication checkpoint activation. This indicated that Rad53 must stably bind to Dbf4 to regulate its activity.

  14. Decrease of NH4+-N by bacterioplankton accelerated the removal of cyanobacterial blooms in aerated aquatic ecosystem.

    PubMed

    Yang, Xi; Xie, Ping; Ma, Zhimei; Wang, Qing; Fan, Huihui; Shen, Hong

    2013-11-01

    We used aerated systems to assess the influence of the bacterioplankton community on cyanobacterial blooms in algae/post-bloom of Lake Taihu, China. Bacterioplankton community diversity was evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting. Chemical analysis and nitrogen dynamic changes illustrated that NH4+-N was nitrified to NO2--N and NO3--N by bacterioplankton. Finally, NH4+-N was exhausted and NO3--N was denitrified to NO2--N, while the accumulation of NO2--N indicated that bacterioplankton with completely aerobic denitrification ability were lacking in the water samples collected from Lake Taihu. We suggested that adding completely aerobic denitrification bacteria (to denitrify NO2--N to N2) would improve the water quality. PCR-DGGE and sequencing results showed that more than1/3 of the bacterial species were associated with the removal of nitrogen, and Acidovorax temperans was the dominant one. PCR-DGGE, variation of nitrogen, removal efficiencies of chlorophyll-a and canonical correspondence analysis indicated that the bacterioplanktonsignificantly influenced the physiological and biochemical changes of cyanobacteria. Additionally, the unweighted pair-group method with arithmetic means revealed there was no obvious harm to the microecosystem from aeration. The present study demonstrated that bacterioplankton can play crucial roles in aerated ecosystems, which could control the impact of cyanobacterial blooms in eutrophicated fresh water systems.

  15. Determining a Structural Distortion and Anion Ordering in La2Si4N6C via Computation and Experiment.

    PubMed

    Hermus, Martin; Mansouri Tehrani, Aria; Brgoch, Jakoah

    2016-09-19

    A structural instability in the orthorhombic carbonitridosilicate La2Si4N6C arises when calculating the ab initio phonon dispersion curves. The presence of imaginary modes indicates the compound reported in space group Pnma is dynamically unstable with the eigenvectors showing a monoclinic distortion pathway leading to space group P21/c. Synthesizing La2Si4N6C using a high-temperature route and conducting a co-refinement with high-resolution synchrotron X-ray and neutron powder diffraction shows the predicted peak splitting confirming the predicted lower symmetry crystal structure. Further, the combination of ab initio computation, neutron diffraction, and a total scattering analysis based on a neutron pair distribution function analysis supports that the anions are fully ordered and that carbon is only found on the central position of a star-shaped C(SiN3)4 unit. These results illustrate the power of combining computation and experiment to unequivocally solve crystal structures from polycrystalline powders. PMID:27598316

  16. Transparent half metallic g-C4N3 nanotubes: potential multifunctional applications for spintronics and optical devices.

    PubMed

    Hu, Tao; Hashmi, Arqum; Hong, Jisang

    2014-08-14

    Multifunctional material brings many interesting issues because of various potential device applications. Using first principles calculations, we predict that the graphitic carbon nitride (g-C4N3) nanotubes can display multifunctional properties for both spintronics and optical device applications. Very interestingly, armchair tubes (n, n) with n = 2, 3, 4, 5, 6 and (5, 0) zigzag tubes are found to be half metallic, while zigzag tubes (n, 0) with n = 4, 6 show an antiferromagnetic ground state with band gaps. However, larger zigzag tubes of (7, 0), (8, 0), and (10, 0) are turned out to be half metallic. Along with the half metallic behavior of the tubes, those tubes seem to be optically transparent in the visible range. Due to these magnetic and optical properties, we suggest that the g-C4N3 nanotubes (CNNTs) can be used for both ideal spintronics and transparent electrode materials. We also explored the stability of magnetic state and nanotube structure using ab initio molecular dynamics. The CNNTs were found to be thermally stable and the magnetic moment was robust against the structural deformation at 300 K. Overall, our theoretical prediction in one dimensional CNNTs may provide a new physics in spintronics and also in other device applications because of potential multifunctional properties.

  17. Inhibitory effect of high NH4(+)-N concentration on anaerobic biotreatment of fresh leachate from a municipal solid waste incineration plant.

    PubMed

    Liu, Zhao; Dang, Yan; Li, Caihua; Sun, Dezhi

    2015-09-01

    Fresh leachate from municipal solid waste (MSW) incineration plants generally contains extremely high NH4(+)-N concentration which could inhibit the bioactivity of microorganisms. The inhibitory effect of high NH4(+)-N concentration on anaerobic biotreatment of fresh leachate from a MSW incineration plant in China has been investigated in this study. The inhibition processes was studied by both static tests and a laboratory-scale expanded granular sludge bed (EGSB) reactor. The specific methanogenic activity (SMA) of the microorganisms in anaerobic granular sludge was inhibited with the NH4(+)-N concentration increasing to 1000mg/L in static tests. As well the chemical oxygen demand (COD) removal efficiency and the methane yield decreased in the EGSB reactor, while the volatile fatty acids (VFAs) accumulated and extracellular polymeric substances (EPS) of the anaerobic granular sludge increased with NH4(+)-N concentration rising to 1000mg/L, without any rebounding during 30days of operation. Decreasing NH4(+)-N concentration to 500mg/L in influent, the COD removal efficiency recovered to about 85% after 26days. 1000mg/L of NH4(+)-N in leachate was suggested to be the inhibition threshold in EGSB reactor. High-throughput sequencing results showed little changes in microbial communities of the sludge for a high NH4(+)-N concentration, indicating that the survival of most microorganisms was not affected under such a condition. It inhibited the bioactivity of the microorganisms, resulting in decrease of the COD removal efficiency.

  18. Water clustering on nanostructured iron oxide films

    NASA Astrophysics Data System (ADS)

    Merte, Lindsay R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Lægsgaard, Erik; Wendt, Stefan; Mavrikakis, Manos; Besenbacher, Flemming

    2014-06-01

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule-molecule and molecule-surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moiré-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moiré structure.

  19. Water Clustering on Nanostructured Iron Oxide Films

    SciTech Connect

    Merte, L. R.; Bechstein, Ralf; Peng, Guowen; Rieboldt, Felix; Farberow, Carrie A.; Zeuthen, Helene; Knudsen, Jan; Laegsgaard, E.; Wendt, Stefen; Mavrikakis, Manos; Besenbacher, Fleming

    2014-06-30

    The adhesion of water to solid surfaces is characterized by the tendency to balance competing molecule–molecule and molecule–surface interactions. Hydroxyl groups form strong hydrogen bonds to water molecules and are known to substantially influence the wetting behaviour of oxide surfaces, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire´-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer islands form on the are film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous water are found to coexist at adjacent hydroxylated and hydroxyl-free domains of the moire´ structure.

  20. 3D Visualization of the Iron Oxidation State in FeO/Fe3O4 Core-Shell Nanocubes from Electron Energy Loss Tomography.

    PubMed

    Torruella, Pau; Arenal, Raúl; de la Peña, Francisco; Saghi, Zineb; Yedra, Lluís; Eljarrat, Alberto; López-Conesa, Lluís; Estrader, Marta; López-Ortega, Alberto; Salazar-Alvarez, Germán; Nogués, Josep; Ducati, Caterina; Midgley, Paul A; Peiró, Francesca; Estradé, Sonia

    2016-08-10

    The physicochemical properties used in numerous advanced nanostructured devices are directly controlled by the oxidation states of their constituents. In this work we combine electron energy-loss spectroscopy, blind source separation, and computed tomography to reconstruct in three dimensions the distribution of Fe(2+) and Fe(3+) ions in a FeO/Fe3O4 core/shell cube-shaped nanoparticle with nanometric resolution. The results highlight the sharpness of the interface between both oxides and provide an average shell thickness, core volume, and average cube edge length measurements in agreement with the magnetic characterization of the sample. PMID:27383904

  1. 3D Visualization of the Iron Oxidation State in FeO/Fe3O4 Core-Shell Nanocubes from Electron Energy Loss Tomography.

    PubMed

    Torruella, Pau; Arenal, Raúl; de la Peña, Francisco; Saghi, Zineb; Yedra, Lluís; Eljarrat, Alberto; López-Conesa, Lluís; Estrader, Marta; López-Ortega, Alberto; Salazar-Alvarez, Germán; Nogués, Josep; Ducati, Caterina; Midgley, Paul A; Peiró, Francesca; Estradé, Sonia

    2016-08-10

    The physicochemical properties used in numerous advanced nanostructured devices are directly controlled by the oxidation states of their constituents. In this work we combine electron energy-loss spectroscopy, blind source separation, and computed tomography to reconstruct in three dimensions the distribution of Fe(2+) and Fe(3+) ions in a FeO/Fe3O4 core/shell cube-shaped nanoparticle with nanometric resolution. The results highlight the sharpness of the interface between both oxides and provide an average shell thickness, core volume, and average cube edge length measurements in agreement with the magnetic characterization of the sample.

  2. Feature Scale Simulation of PECVD of SiO2 in SiH4/N2O Mixture

    NASA Astrophysics Data System (ADS)

    Liu, Xuan; Ge, Jie; Yang, Yi; Song, Yixu; Ren, Tianling

    2014-04-01

    In this paper, to simulate the process of PECVD (plasma enhanced chemical vapor deposition) of SiO2, the plasma chemistry and plasma density of SiH4/N2O mixture have been studied with an inductive coupled plasma model, and the level set methodology has been used to obtain the feature scale variation during the process. In this simulation, the goal is to fill a trench. We studied how ion sputtering and chamber pressure affect the feature scale model. After the simulation, we found that the trench will close up at the top after a few steps, and if we add the ion sputtering into the surface reactions, the trench top will close up a little later. When the chamber pressure is improved, the plasma density will increase, so the trench top will close up earlier. In semiconductor device manufacture, people can control the trench's feature scale through adjusting these two parameters.

  3. Synthesis and aromatase inhibitory evaluation of 4-N-nitrophenyl substituted amino-4H-1,2,4-triazole derivatives.

    PubMed

    Song, Zhidan; Liu, Yanchun; Dai, Zhoutong; Liu, Wei; Zhao, Kai; Zhang, Tongcun; Hu, Yanying; Zhang, Xiuli; Dai, Yujie

    2016-10-01

    In this paper, 13 4-N-nitrophenyl substituted amino-4H-1,2,4-triazole derivatives were synthesized and their aromatase inhibitory activities were measured. The results show that the substitution of the groups on benzyl group can further improve their bioactivity and the compound with Cl on the para position of benzyl has the highest bioactivity (IC50=9.02nM). A QSAR model was constructed from the 13 compounds with genetic function approximation using DS 2.1 package. This model can explain 90.09% of the variance (R(2)Adj), while it can predict 84.95% of the variance (R(2)cv) with the confidence interval of 95%. PMID:27567077

  4. Cross section limits for the Cm248(Mg25,4n-5n)Hs268,269 reactions

    NASA Astrophysics Data System (ADS)

    Dvorak, J.; Brüchle, W.; Düllmann, Ch. E.; Dvorakova, Z.; Eberhardt, K.; Eichler, R.; Jäger, E.; Nagame, Y.; Qin, Z.; Schädel, M.; Schausten, B.; Schimpf, E.; Schuber, R.; Semchenkov, A.; Thörle, P.; Türler, A.; Wegrzecki, M.; Yakushev, A.

    2009-03-01

    We report on an attempt to produce and detect Hs268 and Hs269 in the nuclear fusion reaction Mg25+Cm248 using the gas phase chemistry apparatus COMPACT. No decay chains attributable to the decay of hassium isotopes were observed during the course of this experiment. From the nonobservation of Hs269 we derive a cross section limit of 0.4 pb (63% confidence limit) for the reaction Cm248(Mg25,4n)Hs269 at a center-of-target beam energy of 140 MeV. The evaluated cross section limit for the Cm248(Mg25,5n)Hs268 reaction depends on the assumed half-life of unknown Hs268. Current systematics of the half-lives for even-even Hs isotopes suggests a value of 0.5 s, resulting in a cross section limit of 1.3 pb.

  5. Electronic structure and magnetism in g-C{sub 4}N{sub 3} controlled by strain engineering

    SciTech Connect

    Liu, L. Z.; Liu, X. X.; Wu, X. L. E-mail: paul.chu@cityu.edu.hk; Chu, Paul K. E-mail: paul.chu@cityu.edu.hk

    2015-03-30

    Regulation of magnetism and half-metallicity has attracted much attention because of its potential in spintronics. The magnetic properties and electronic structure of graphitic carbon nitride (g-C{sub 4}N{sub 3}) with external strain are determined theoretically based on the density function theory and many-body perturbation theory (G{sub 0}W{sub 0}). Asymmetric deformation induced by uniaxial strain not only regulates the magnetic characteristics but also leads to a transformation from half-metallicity to metallicity. However, this transition cannot occur in the structure with symmetric deformation induced by biaxial strain. Our results suggest the use of strain engineering in metal-free spintronics applications.

  6. Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate.

    PubMed

    Krishna Kumar, M; Sudhahar, S; Bhagavannarayana, G; Mohan Kumar, R

    2014-05-01

    Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. PMID:24531108

  7. Measurements of the dielectric and viscoelastic constants in mixtures of 4,4'-n-octyl-cyanobiphenyl and biphenyl.

    PubMed

    Oswald, Patrick; Scalliet, Camille

    2014-03-01

    We performed measurements of the dielectric constants, splay elastic constant, and rotational viscosity of the nematic phase of mixtures of 4,4'-n-octyl-cyanobiphenyl (8CB) and biphenyl (BP). In contrast with previous results of DasGupta et al. [Phys. Rev. E 63, 041703 (2001); Phys. Lett. A 288, 323 (2001)], we do not find any anomaly of these constants when the smectic-A phase is approached at all concentrations of BP. These results are compatible with recent calorimetric measurements of Denolf et al. [Phys. Rev. Lett. 97, 107801 (2006); Phys. Rev. E 76, 051702 (2007)] and the absence of a tricritical point in the phase diagram. The origin of the anomalies observed by DasGupta et al. at large concentration of BP is also briefly discussed and a likely explanation in terms of biphenyl evaporation is proposed.

  8. A Termolecular Reaction Mechanism for Nitrogen Incorporation in Aerosol Produced by Far UV Irradiation of CH4-N2 Atmospheres

    NASA Astrophysics Data System (ADS)

    Hicks, R. K.; Trainer, M. G.; Jimenez, J. L.; Yung, Y. L.; Toon, O. B.; Tolbert, M. A.

    2012-12-01

    Results from the Aerosol Collector and Pyrolyser located onboard the Huygens lander reveal the presence of carbon and nitrogen in Titan's aerosols. Nitrogen incorporation is thought to be initiated by energy sources strong enough to break the N-N triple bond of molecular nitrogen (9.8eV). Such energy sources include extreme UV photons (λ <120 nm) and electrons from Saturn's magnetosphere. Less energetic photons in the far UV (120-200 nm) penetrate to the stratosphere of Titan and are only expected to affect hydrocarbon photochemistry there. However, recent results from our laboratory indicate a surprising amount of nitrogen incorporation- up to 16% by mass- in Titan aerosol analog produced by photochemistry initiated by far UV irradiation of CH4/N2 mixtures. The termolecular reaction CH + N2 + M --> HCN2 has been proposed to account for this observation. Here, we test this hypothesis by using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) to measure the mass loading and chemical composition of aerosol produced at a range of pressures from roughly 0.1 to 1 atm. Even though these gas mixtures spanned an order of magnitude in pressure, they experienced the same residence time in the photochemical chamber and had the same methane optical depth. We report a 150% increase in aerosol mass loading across the range of pressures studied, indicating that the mechanism controlling the total mass produced depends on pressure. We also report an overall increase with pressure in the ratio of nitrogen-bearing organic species to hydrocarbon-only species. These observations support the hypothesis that the termolecular reaction above is responsible for the incorporation of nitrogen into Titan aerosol analog produced from CH4/N2 gas mixtures irradiated in the far UV. These findings have implications for our understanding of the evolution of Titan's atmosphere, and the atmospheric synthesis of biologically relevant N-containing molecules.

  9. Improvement of RNA-SIP by pyrosequencing to identify putative 4-n-nonylphenol degraders in activated sludge.

    PubMed

    Zemb, O; Lee, M; Gutierrez-Zamora, M L; Hamelin, J; Coupland, K; Hazrin-Chong, N H; Taleb, I; Manefield, M

    2012-03-01

    Nonylphenols (NP) have estrogenic potential because of their phenolic ring, but the organisms involved in the degradation of this alkylated phenol remain unidentified. Using 16S ribosomal RNA (rRNA)-based stable isotope probing (SIP) and a new method based on pyrosequencing, we identified the bacteria involved in the degradation of the aromatic ring of [U-ring-(13)C] 4-n-NP in aerobic sludge. The first order degradation rate of 4-n-NP was 5.5d(-1). Single strand conformation polymorphism of density-separated labeled and unlabeled 16S rRNA showed significant differences and enabled selection of four representative fractions for pyrosequencing. Nineteen phylotypes showed a significant enrichment in the heavy fraction in the labeled pulse. The relative abundances of these phylotypes were combined with the RNA concentration of each fraction to yield a simple model of the distribution of each phylotype across the gradient. This model was used to estimate the percentage of labeling for each phylotype. The sequences showing the highest labeling (11%) were closely related to Afipia sp. but represented only 2 % of the RNA in the heavy fraction of the labeled pulse. The sequences representing the largest proportion of the RNA in the heavy fraction were related to Propionibacterium acnes and Frateuria aurantia, which are known to possess enzymes for phenol degradation. The model shows that despite Afipia having the highest (13)C enrichment, other species encoding phenol degradation pathways are responsible for more (13)C incorporation. Last, we showed that some species represent 12% of the total RNA but contain only 1% (13)C above natural abundance.

  10. Comparisons of the structure of stoichiometric CH sub 4 -N sub 2 O-Ar and CH sub 4 O sub 2 -Ar flames by molecular beam sampling and mass spectrometric analysis

    SciTech Connect

    Vandooren, J.; Branch, M.C.; Van Tiggelen, P.J. )

    1992-09-01

    In this paper, measurements are reported of the profiles of composition and temperature in laminar premixed flat flames of CH{sub 4}-N{sub 2}O-Ar and CH{sub 4}-O{sub 2}-Ar. Measurements were made in near stoichiometric mixtures at 30 torr by molecular beam sampling and mass spectrometric sample analysis. All major stable species and many important unstable species were measured by this technique, many species being identified in the flame with N{sub 2}O as oxidizer for the first time. Calibration of the concentration profiles was accomplished by the use of calibration gases for stable species and by comparison of the mass spectrometer signal in the well-characterized CH{sub 4}0O{sub 2}-Ar flame with signals in the CH{sub 4}-N{sub 2}O-Ar flame and by partial equilibrium for the hydrogen-oxygen system. The measurements have identified the presence of NCO, HCN, and HNCO as reaction intermediates and the importance of these species in the reaction mechanism is discussed.

  11. A novel yellow-emitting SrAlSi4N7:Ce3+ phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Ruan, Jian; Xie, Rong-Jun; Funahashi, Shiro; Tanaka, Yoshinori; Takeda, Takashi; Suehiro, Takayuki; Hirosaki, Naoto; Li, Yuan-Qiang

    2013-12-01

    Ce3+-doped and Ce3+/Li+-codoped SrAlSi4N7 phosphors were synthesized by gas pressure sintering of powder mixtures of Sr3N2, AlN, α-Si3N4, CeN and Li3N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi4N7:Ce3+(Ce3+/Li+) were investigated in this work. The band structure calculated by the DMol3 code shows that SrAlSi4N7 has a direct band gap of 3.87 eV. The single crystal analysis of Ce3+-doped SrAlSi4N7 indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi4N7 was identified as a major phase of the fired powders, and Sr5Al5Si21N35O2 and AlN as minor phases. Both Ce3+ and Ce3+/Li+ doped SrAlSi4N7 phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce3+/Li+-doped SrAlSi4N7 (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr0.97Al1.03Si3.997N\\94\\maccounttest14=t0005_18193 7:Ce3+0.03 with a commercial blue InGaN chip. It indicates that SrAlSi4N7:Ce3+ is a promising yellow emitting down-conversion phosphor for white LEDs.

  12. Self-limiting and complete oxidation of silicon nanostructures produced by laser ablation in water

    NASA Astrophysics Data System (ADS)

    Vaccaro, L.; Popescu, R.; Messina, F.; Camarda, P.; Schneider, R.; Gerthsen, D.; Gelardi, F. M.; Cannas, M.

    2016-07-01

    Oxidized Silicon nanomaterials produced by 1064 nm pulsed laser ablation in deionized water are investigated. High-resolution transmission electron microscopy coupled with energy dispersive X-ray spectroscopy allows to characterize the structural and chemical properties at a sub-nanometric scale. This analysis clarifies that laser ablation induces both self-limiting and complete oxidation processes which produce polycrystalline Si surrounded by a layer of SiO2 and amorphous fully oxidized SiO2, respectively. These nanostructures exhibit a composite luminescence spectrum which is investigated by time-resolved spectroscopy with a tunable laser excitation. The origin of the observed luminescence bands agrees with the two structural typologies: Si nanocrystals emit a μs-decaying red band; defects of SiO2 give rise to a ns-decaying UV band and two overlapping blue bands with lifetime in the ns and ms timescale.

  13. Magnetic iron oxide nanoparticles as drug delivery system in breast cancer

    NASA Astrophysics Data System (ADS)

    Marcu, A.; Pop, S.; Dumitrache, F.; Mocanu, M.; Niculite, C. M.; Gherghiceanu, M.; Lungu, C. P.; Fleaca, C.; Ianchis, R.; Barbut, A.; Grigoriu, C.; Morjan, I.

    2013-09-01

    Present work was focused on producing improved iron oxide nanoparticles for targeted drug delivery in breast cancer. Nanometric-sized iron oxide particles were synthesized by laser pyrolysis and were morphologically/structurally characterized. These new nanoparticles were compared with some commercial, chemically prepared iron oxide ones. Cytotoxicity and the anti-proliferation effects of nanoparticles were tested in vitro on the breast adenocarcinoma cell line MCF-7. Nanoparticles were further coated with the antracyclinic antibiotic Violamycine B1 and tested for the anti-tumor effect on MCF-7 cells. The nanoparticles produced by us seem more effective in vitro than the commercial ones, with respect to cellular uptake and VB1 delivery. Violamycine B1 bound on nanoparticles is as efficient as the free form, but is better delivered into tumor cells.

  14. Synthesis, molecular structure, and catalytic potential of the tetrairon complex [Fe4(N3O2-L)4(mu-O)2]4+ (L = 1-carboxymethyl-4,7-dimethyl-1,4,7-triazacyclononane).

    PubMed

    Romakh, Vladimir B; Therrien, Bruno; Süss-Fink, Georg; Shul'pin, Georgiy B

    2007-04-16

    The reaction of iron sulfate with 1-carboxymethyl-4,7-dimethyl-1,4,7-triazacyclononane (L) and hydrogen peroxide in aqueous ethanol gives a brown dinuclear complex considered to be [Fe2(N3O-L)2(mu-O)(mu-OOCCH3)] + (1), which converts upon standing in acetonitrile solution into the green tetranuclear complex [Fe4(N3O2-L)4(mu-O)2]4+ (2). A single-crystal X-ray structure analysis of [2][PF6]4.5MeCN reveals 2 to contain four iron(III) centers, each of which is coordinated to three nitrogen atoms of a triazacyclononane ligand and is bridged by one oxo and two carboxylato bridges, a structural feature known from the active center of methane monooxygenase. Accordingly, complex 2 was found to catalyze the oxidative functionalization of methane with hydrogen peroxide in aqueous solution to give methanol, methyl hydroperoxide, and formic acid; the total turnover numbers attain 24 catalytic cycles within 4 h. To gain more insight into the catalytic process, the catalytic potential of 2 was also studied for the oxidation of higher alkanes, cycloalkanes, and isopropanol in acetonitrile, as well as in aqueous solution. The bond selectivities of the oxidation of linear and branched alkanes suggest a ferroxy radical pathway.

  15. Reconstructing fluid-flow events in Lower-Triassic sandstones of the eastern Paris Basin by elemental tracing and isotopic dating of nanometric illite crystals

    NASA Astrophysics Data System (ADS)

    Blaise, Thomas; Clauer, Norbert; Cathelineau, Michel; Boiron, Marie-Christine; Techer, Isabelle; Boulvais, Philippe

    2016-03-01

    Lower- to Middle-Triassic sandstones from eastern Paris Basin were buried to a maximum depth of 2500 m at a paleo-temperature of about 100 °C. They contain extensive amounts of authigenic platy and filamentous illite particles similar to those reported in reservoirs generally buried at 3000 to -5000 m and subjected to temperatures of 120 to -150 °C. To evaluate this unexpected occurrence, such sandstones were collected from drill cores between 1825 and 2000 m depth, and nanometric-sized sub-fractions were separated. The illite crystals were identified by XRD, observed by SEM and TEM, analyzed for their major, trace, rare-earth elements and oxygen isotope compositions, and dated by K-Ar and Rb-Sr. Illite particles display varied growth features in the rock pore-space and on authigenic quartz and adularia that they postdate. TEM-EDS crystal-chemical in situ data show that the illite lath/fiber and platelet morphologies correspond at least to two populations with varied interlayer charges: between 0.7 and 0.9 for the former and between 0.8 and 1.0 for the latter, the Fe/Fe + Mg ratio being higher in the platelets. Except for the deeper conglomerate, the PAAS-normalized REE patterns of the illite crystals are bell-shaped, enriched in middle REEs. Ca-carbonates and Ca-phosphates were detected together with illite in the separates. These soluble components yield 87Sr/86Sr ratios that are not strictly in chemical equilibrium with the illite crystals, suggesting successive fluids flows with different chemical compositions. The K-Ar data of finer <0.05 μm illite separates confirm two crystallization events at 179.4 ± 4.5 and 149.4 ± 2.5 Ma during the Early and Late Jurassic. The slightly coarser fractions contain also earlier crystallized or detrital K-bearing minerals characterized by lower δ18O values. The δ18O of the finest authigenic illite separates tends to decrease slightly with depth, from 18.2 (±0.2) to 16.3 (±0.2)‰, suggesting different but

  16. Continuously Controlled Optical Band Gap in Oxide Semiconductor Thin Films.

    PubMed

    Herklotz, Andreas; Rus, Stefania Florina; Ward, Thomas Zac

    2016-03-01

    The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. Charge density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques. PMID:26836282

  17. Continuously controlled optical band gap in oxide semiconductor thin films

    DOE PAGES

    Herklotz, Andreas; Rus, Stefania Florina; Ward, Thomas Zac

    2016-02-02

    The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. In conclusion, chargemore » density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques.« less

  18. Two-dimensional shape memory graphene oxide

    PubMed Central

    Chang, Zhenyue; Deng, Junkai; Chandrakumara, Ganaka G.; Yan, Wenyi; Liu, Jefferson Zhe

    2016-01-01

    Driven by the increasing demand for micro-/nano-technologies, stimuli-responsive shape memory materials at nanoscale have recently attracted great research interests. However, by reducing the size of conventional shape memory materials down to approximately nanometre range, the shape memory effect diminishes. Here, using density functional theory calculations, we report the discovery of a shape memory effect in a two-dimensional atomically thin graphene oxide crystal with ordered epoxy groups, namely C8O. A maximum recoverable strain of 14.5% is achieved as a result of reversible phase transition between two intrinsically stable phases. Our calculations conclude co-existence of the two stable phases in a coherent crystal lattice, giving rise to the possibility of constructing multiple temporary shapes in a single material, thus, enabling highly desirable programmability. With an atomic thickness, excellent shape memory mechanical properties and electric field stimulus, the discovery of a two-dimensional shape memory graphene oxide opens a path for the development of exceptional micro-/nano-electromechanical devices. PMID:27325441

  19. Two-dimensional shape memory graphene oxide

    NASA Astrophysics Data System (ADS)

    Chang, Zhenyue; Deng, Junkai; Chandrakumara, Ganaka G.; Yan, Wenyi; Liu, Jefferson Zhe

    2016-06-01

    Driven by the increasing demand for micro-/nano-technologies, stimuli-responsive shape memory materials at nanoscale have recently attracted great research interests. However, by reducing the size of conventional shape memory materials down to approximately nanometre range, the shape memory effect diminishes. Here, using density functional theory calculations, we report the discovery of a shape memory effect in a two-dimensional atomically thin graphene oxide crystal with ordered epoxy groups, namely C8O. A maximum recoverable strain of 14.5% is achieved as a result of reversible phase transition between two intrinsically stable phases. Our calculations conclude co-existence of the two stable phases in a coherent crystal lattice, giving rise to the possibility of constructing multiple temporary shapes in a single material, thus, enabling highly desirable programmability. With an atomic thickness, excellent shape memory mechanical properties and electric field stimulus, the discovery of a two-dimensional shape memory graphene oxide opens a path for the development of exceptional micro-/nano-electromechanical devices.

  20. Two-dimensional shape memory graphene oxide.

    PubMed

    Chang, Zhenyue; Deng, Junkai; Chandrakumara, Ganaka G; Yan, Wenyi; Liu, Jefferson Zhe

    2016-01-01

    Driven by the increasing demand for micro-/nano-technologies, stimuli-responsive shape memory materials at nanoscale have recently attracted great research interests. However, by reducing the size of conventional shape memory materials down to approximately nanometre range, the shape memory effect diminishes. Here, using density functional theory calculations, we report the discovery of a shape memory effect in a two-dimensional atomically thin graphene oxide crystal with ordered epoxy groups, namely C8O. A maximum recoverable strain of 14.5% is achieved as a result of reversible phase transition between two intrinsically stable phases. Our calculations conclude co-existence of the two stable phases in a coherent crystal lattice, giving rise to the possibility of constructing multiple temporary shapes in a single material, thus, enabling highly desirable programmability. With an atomic thickness, excellent shape memory mechanical properties and electric field stimulus, the discovery of a two-dimensional shape memory graphene oxide opens a path for the development of exceptional micro-/nano-electromechanical devices.

  1. Comparative study on the inclusion behavior between meso-tetrakis(4- N-ethylpyridiniurmyl)porphyrin and β-cyclodextrin derivatives

    NASA Astrophysics Data System (ADS)

    Xiliang, Guo; Shaomin, Shuang; Chuan, Dong; Feng, Feng; Wong, M. S.

    2005-01-01

    5,10,15,20-Tetrakis(4- N-ethylpyridiniurmyl)porphyrin (TEPyP) formed 1:1 stoichiometry inclusion complexes with β-cyclodextrin (β-CD) and its derivatives including hydroxypropyl-β-cyclodextrin (HP-β-CD), sulfobutylether-β-cyclodextrin (SBE-β-CD) in basic aqueous solution. The supramolecular system was investigated by the methods of fluorescence, UV-vis absorption spectroscopy, nuclear magnetic resonance (NMR) technique. The inclusion ability of cyclodextrins exhibited remarkable difference for β-CD, HP-β-CD and SBE-β-CD. Association constants as high as K=1.1×10 4 M -1 in the case of HP-β-CD/TEPyP and 2.0×10 5 M -1 in the case of SBE-β-CD/TEPyP complexes were determined, whereas a lower value ( K=550 M -1) was given in the case of β-CD/TEPyP. The results showed that hydrogen bonding and charge attraction play important roles in the processes of host-guest interaction. The interaction mechanism of inclusion processes could be explained by the analysis of NMR spectroscopy. The supramolecular assembly was formed. β-CD and HP-β-CD approached from the primary face of cavities of CDs.

  2. Comparative study on the inclusion behavior between meso-tetrakis(4-N-ethylpyridiniurmyl)porphyrin and beta-cyclodextrin derivatives.

    PubMed

    Xiliang, Guo; Shaomin, Shuang; Chuan, Dong; Feng, Feng; Wong, M S

    2005-01-14

    5,10,15,20-Tetrakis(4-N-ethylpyridiniurmyl)porphyrin (TEPyP) formed 1:1 stoichiometry inclusion complexes with beta-cyclodextrin (beta-CD) and its derivatives including hydroxypropyl-beta-cyclodextrin (HP-beta-CD), sulfobutylether-beta-cyclodextrin (SBE-beta-CD) in basic aqueous solution. The supramolecular system was investigated by the methods of fluorescence, UV-vis absorption spectroscopy, nuclear magnetic resonance (NMR) technique. The inclusion ability of cyclodextrins exhibited remarkable difference for beta-CD, HP-beta-CD and SBE-beta-CD. Association constants as high as K=1.1 x 10(4) M(-1) in the case of HP-beta-CD/TEPyP and 2.0 x 10(5) M(-1) in the case of SBE-beta-CD/TEPyP complexes were determined, whereas a lower value (K=550 M(-1)) was given in the case of beta-CD/TEPyP. The results showed that hydrogen bonding and charge attraction play important roles in the processes of host-guest interaction. The interaction mechanism of inclusion processes could be explained by the analysis of NMR spectroscopy. The supramolecular assembly was formed. beta-CD and HP-beta-CD approached from the primary face of cavities of CDs.

  3. A "high 4He/3He" mantle material detected under the East Pacific Rise (15°4'N)

    NASA Astrophysics Data System (ADS)

    Mougel, Berengere; Moreira, Manuel; Agranier, Arnaud

    2015-03-01

    We investigate in details helium isotope data reported in Mougel et al. (2014) for 14 basaltic samples collected on the East Pacific Rise by submersible (15°4'N) where the ridge interacts with the Mathematician seamounts. Samples locations are separated by only few hundred meters across a 15 km along-axis profile. The data reveal a strong geochemical variability that has never been observed at such high spatial resolution for helium isotope compositions. Moreover, they reveal an unusually high 4He/3He mantle component also characterized by unradiogenic lead, atypical in oceanic basalts. He-Pb systematics suggests a mixture between a nonradiogenic lead and radiogenic helium pyroxenitic component, recycled from the deep continental lithosphere and the ambient peridotitic mantle. The He isotope difference between these two end-members can be interpreted as a time evolution of two distinct mantle sources after a slight (U + Th)/3He fractionation, likely due to some ancient degassing during the formation of deep continental pyroxenites.

  4. Photodynamic Therapy of the Murine LM3 Tumor Using Meso-Tetra (4-N,N,N-Trimethylanilinium) Porphine

    PubMed Central

    Colombo, L. L.; Juarranz, A.; Cañete, M.; Villanueva, A.; Stockert, J. C.

    2007-01-01

    Photodynamic therapy (PDT) of cancer is based on the cytotoxicity induced by a photosensitizer in the presence of oxygen and visible light, resulting in cell death and tumor regression. This work describes the response of the murine LM3 tumor to PDT using meso-tetra (4-N,N,N-trimethylanilinium) porphine (TMAP). BALB/c mice with intradermal LM3 tumors were subjected to intravenous injection of TMAP (4 mg/kg) followed 24 h later by blue-red light irradiation (λmax: 419, 457, 650 nm) for 60 min (total dose: 290 J/cm2) on depilated and glycerol-covered skin over the tumor of anesthetized animals. Control (drug alone, light alone) and PDT treatments (drug + light) were performed once and repeated 48 h later. No significant differences were found between untreated tumors and tumors only treated with TMAP or light. PDT-treated tumors showed almost total but transitory tumor regression (from 3 mm to less than 1 mm) in 8/9 animals, whereas no regression was found in 1/9. PDT response was heterogeneous and each tumor showed different regression and growth delay. The survival of PDT-treated animals was significantly higher than that of TMAP and light controls, showing a lower number of lung metastasis but increased tumor-draining lymph node metastasis. Repeated treatment and reduction of tissue light scattering by glycerol could be useful approaches in studies on PDT of cancer. PMID:23675051

  5. Competitive sorption between 17alpha-ethinyl estradiol and bisphenol A/4-n-nonylphenol by soils.

    PubMed

    Li, Jianzhong; Jiang, Lu; Xiang, Xi; Xu, Shuang; Wen, Rou; Liu, Xiang

    2013-06-01

    The sorption of 17alpha-ethinyl estradiol (EE2), bisphenol A (BPA), and 4-n-nonylphenol (NP) in single systems and the sorption of EE2 with different initial aqueous concentrations of BPA or NP were examined using three soils. Results showed that all sorption isotherms were nonlinear and fit the Freundlich model. The degree of nonlinearity was in the order BPA (0.537-0.686) > EE2 (0.705-0.858) > NP (0.875-0.0.951) in single systems. The isotherm linearity index of EE2 sorption calculated by the Freundlich model for Loam, Silt Loam and Silt increased from 0.758, 0.705 and 0.858, to 0.889, 0.910 and 0.969, respectively, when BPA concentration increased from 0 to 1000 microg/L, but the effect of NP was comparably minimal. Additionally, EE2 significantly suppressed the sorption of BPA, but insignificantly suppressed that of NP. These findings can be attributed to the difference of sorption affinity of EE2, NP and BPA on the hard carbon (e.g., black carbon) of soil organic matter that dominated the sorption in the low equilibrium aqueous concentration range of endocrine-disrupting chemicals (EDCs). Competitive sorption among EDCs presents new challenges for predicting the transport and fate of EDCs under the influence of co-solutes.

  6. Transition metal complexes of Vanillin- 4N-(2-pyridyl) thiosemicarbazone (H 2VPT); thermal, structural and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    El-Reash, Gaber Abu; El-Ayaan, Usama; Gabr, I. M.; El-Rachawy, El-Bastawesy

    2010-04-01

    The present work carried out a study on the ligational behavior of the new ligand, Vanillin- 4N-(2-pyridyl) thiosemicarbazone (H 2VPT) 1 towards some transition metal ions namely, Mn 2+, Co 2+, Ni 2+, Cu 2+, Zn 2+,Cd 2+, Hg 2+ and U 6+. These complexes namely [Mn(HVPT)Cl] 2, [Co(VPT)(H 2O)] 2H 2O 3, [Ni(HVPT)Cl(H 2O)] 4, [Cu(HVPT)Cl(H 2O)] 5, [Zn(VPT)(H 2O)]H 2O 6, [Cd(HVPT)Cl(H 2O)] 7, [Hg(VPT)(H 2O)]H 2O 8 and [UO 2(H 2VPT)(OAc) 2]H 2O 9, were characterized by elemental analysis, spectral (IR, 1H NMR and UV-vis) and magnetic moment measurements. The suggested structures were confirmed by applying geometry optimization and conformational analysis. Thermal properties and decomposition kinetics of all compounds are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters ( E, A, Δ H, Δ S and Δ G) of all thermal decomposition stages have been evaluated using Coats-Redfern equation. ESR spectra of [Cu(HVPT)Cl]H 2O at room temperature show broad signal, indicating spin-exchange interactions between copper(II) ions.

  7. Nuclear Magnetic Resonance Measurements and Electronic Structure of Pu(IV) in [(Me)4N]2PuCl6.

    PubMed

    Mounce, Andrew M; Yasuoka, Hiroshi; Koutroulakis, Georgios; Lee, Jeongseop A; Cho, Herman; Gendron, Frédéric; Zurek, Eva; Scott, Brian L; Trujillo, Julie A; Slemmons, Alice K; Cross, Justin N; Thompson, Joe D; Kozimor, Stosh A; Bauer, Eric D; Autschbach, Jochen; Clark, David L

    2016-09-01

    The synthesis, electronic structure, and characterization via single-crystal X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, and magnetic susceptibility of (Me4N)2PuCl6 are reported. NMR measurements were performed to both search for the direct (239)Pu resonance and to obtain local magnetic and electronic information at the Cl site through (35)Cl and (37)Cl spectra. No signature of (239)Pu NMR was observed. The temperature dependence of the Cl spectra was simulated by diagonalizing the Zeeman and quadrupolar Hamiltonians for (35)Cl, (37)Cl, and (14)N isotopes. Electronic structure calculations predict a magnetic Γ5 triplet ground state of Pu(IV) in the crystalline electric field of the undistorted PuCl6 octahedron. A tetragonal distortion would result in a very small splitting (∼20 cm(-1)) of the triplet ground state into a nonmagnetic singlet and a doublet state. The Cl shifts have an inflection point at T ≈ 15 K, differing from the bulk susceptibility, indicating a nonmagnetic crystal field ground state. The Cl spin-lattice relaxation time is constant to T = 15 K, below which it rapidly increases, also supporting the nonmagnetic crystal field ground state.

  8. General transformation of α cluster model wave function to jj-coupling shell model in various 4N nuclei

    NASA Astrophysics Data System (ADS)

    Itagaki, N.; Matsuno, H.; Suhara, T.

    2016-09-01

    The antisymmetrized quasi-cluster model (AQCM) is a method to describe transitions from the α cluster wave functions to jj-coupling shell model wave functions. In this model, the cluster-shell transition is characterized by only two parameters: R representing the distance between α clusters and Λ describing the breaking of α clusters. The contribution of the spin-orbit interaction, very important in the jj-coupling shell model, can be taken into account starting with the α cluster model wave function. In this article we show the generality of AQCM by extending the application to heavier regions: various 4N nuclei from 4He to 100Sn. The characteristic magic numbers of the jj-coupling shell model, 28 and 50, are described starting with the α cluster model. The competition of two different configurations is discussed in 20Ne (16O + one quasi-cluster and 12C + two quasi-clusters) and 28Si (pentagon shape of five quasi-clusters and 12C + 16O). Also, we compare the energy curves for the α + 40Ca cluster configuration calculated with and without the α breaking effect in 44Ti.

  9. Distortion-sensitive insight into the pretransitional behavior of 4-n-octyloxy-4‧-cyanobiphenyl (8OCB)

    NASA Astrophysics Data System (ADS)

    Rzoska, Sylwester J.; Drozd-Rzoska, Aleksandra; Mukherjee, Prabir K.; Lopez, David O.; Martinez-Garcia, Julio C.

    2013-06-01

    Results of studies of the static and dynamic dielectric properties in rod-like 4-n-octyloxy-4‧-cyanobiphenyl (8OCB) with isotropic (I)-nematic (N)-smectic A (SmA)-crystal (Cr) mesomorphism, combined with measurements of the low-frequency nonlinear dielectric effect and heat capacity are presented. The analysis is supported by the derivative-based and distortion-sensitive transformation of experimental data. Evidence for the I-N and N-SmA pretransitional anomalies, indicating the influence of tricritical behavior, is shown. It has also been found that neither the N phase nor the SmA phase are uniform and hallmarks of fluid-fluid crossovers can be detected. The dynamics, tested via the evolution of the primary relaxation time, is clearly non-Arrhenius and described via τ(T) = τc(T-TC)-ϕ. In the immediate vicinity of the I-N transition a novel anomaly has been found: Δτ ∝ 1/(T - T*), where T* is the temperature of the virtual continuous transition and Δτ is the excess over the ‘background behavior’. Experimental results are confronted with the comprehensive Landau-de Gennes theory based modeling.

  10. Investigation of Seasonal Cycles of CO, CH4, N2O, and O3 in the High Arctic at Eureka, Canada and Barrow, Alaska using Infrared Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tran, S.; Mariani, Z.; Conway, S. A.; Lutsch, E.; Rowe, P. M.; Kasai, Y.; Strong, K.

    2015-12-01

    The High Arctic experiences prolonged periods of total darkness in the winter and continuous daylight in the summer, influencing the atmosphere and its composition in ways that are still not fully understood. Making atmospheric measurements in this remote region is challenging, particularly during polar night when solar-viewing instruments are not operational. By using infrared emission spectroscopy, which is independent of sunlight, we are able to document year-round the total column abundances of carbon monoxide (CO), methane (CH4), nitrous oxide (N2O), and ozone (O3). Measurements made at two Arctic sites are presented in this study: the Polar Environment Atmospheric Research Laboratory (PEARL, Eureka, Nunavut, Canada, 80.05°N, 86.42°W) and the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) facility on the North Slope of Alaska (NSA, Barrow, Alaska, 71.19°N, 156.36°W). At both sites, Extended-range Atmospheric Emitted Radiance Interferometers (E-AERIs), are used to measure the absolute downwelling infrared emission from the atmosphere between 400 and 3000 cm-1. The E-AERI has a moderate resolution of 1 cm-1 and provides information about trace gases columns with high sensitivity to the lower troposphere. At PEARL, the instrument was installed in October 2008. In addition, a similar instrument, the University of Idaho's Polar AERI (P-AERI) was installed at PEARL from March 2006 to June 2009. At NSA, the E-AERI has been operating since February 1998. Total columns of CO, CH4, N2O and O3 have been retrieved from 2006 to 2015 at PEARL and from 1998 to 2014 at NSA using the SFIT4 algorithm. These two datasets will be compared along with measurements made by high-resolution solar-viewing infrared spectrometers located at PEARL and at Poker Flat, Alaska (65.12°N, 147.47°W) to validate our results. These measurements will be used to present the annual, seasonal and diurnal variabilities of trace gases in the high Arctic at two different

  11. Responses of biofilm characteristics to variations in temperature and NH4(+)-N loading in a moving-bed biofilm reactor treating micro-polluted raw water.

    PubMed

    Zhang, Shuangfu; Wang, Yayi; He, Weitao; Wu, Min; Xing, Meiyan; Yang, Jian; Gao, Naiyun; Yin, Daqiang

    2013-03-01

    A pilot-scale moving-bed biofilm reactor (MBBR) for biological treatment of micro-polluted raw water was operated over 400days to investigate the responses of biofilm characteristics and nitrification performance to variations in temperature and NH4(+)-N loading. The mean removal efficiency of NH4(+)-N in the MBBR reached 71.4±26.9%, and batch experiments were performed to study nitrification kinetics for better process understanding. Seven physical-chemical parameters, including volatile solids (VS), polysaccharides (PS) and phospholipids (PL) increased firstly, and then rapidly decreased with increasing temperature and NH4(+)-N loading, and properly characterized the attached biomass during biofilm development and detachment in the MBBR. The biofilm compositions were described by six ratios, e.g., PS/VS and PL/VS ratios showed different variation trends, indicating different responses of PS and PL to the changes in temperature and NH4(+)-N loading. Furthermore, fluorescent in situ hybridization (FISH) analysis revealed that increased NH4(+)-N loadings caused an enrichment of the nitrifying biofilm.

  12. The Richardson constant and barrier inhomogeneity at Au/Si3N4/n-Si (MIS) Schottky diodes

    NASA Astrophysics Data System (ADS)

    Tataroğlu, A.; Pür, F. Z.

    2013-07-01

    Si3N4 films were deposited on n-type silicon substrate by the radio frequency magnetron sputtering technique. The current-voltage (I-V) characteristics of Au/Si3N4/n-Si (metal-insulator-semiconductor) Schottky diodes were investigated in the temperature range of 160-400 K. Experimental results show an abnormal increase in the zero-bias barrier height (BH) (ΦBo) and a decrease in the ideality factor (n) with increasing temperature. This behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution (GD) of BHs. The conventional Richardson plot (ln(Io/T2) versus 1000/T) exhibits a linearity above about 300 K. The values of activation energy (Ea) and Richardson constant (A*) were found to be 0.350 eV and 1.242 × 10-3 A cm-2 K-2 from the slope and the intercept at the ordinate of the linear region of this plot, respectively. Also, we attempted to draw a ΦBo versus q/2kT plot to determine evidence of the GD of BHs, and the values of \\bar \\Phi _{{\\rm{Bo}}} = 0.999\\,{\\rm{eV}} and σs = 0.137 eV for the mean BH and zero-bias standard deviation, respectively, were obtained from this plot; then, a modified ln(Io/T2) - q2σs2/2k2T2 versus q/kT plot gives \\bar \\Phi _{{\\rm{Bo}}} and A* as 0.992 eV and 108.228 A cm-2 K-2, respectively. This value of A* is very close to the theoretical value of 112 A cm-2 K-2 for n-type Si.

  13. Capacitance and conductance characterization of nano-ZnGa{sub 2}Te{sub 4}/n-Si diode

    SciTech Connect

    Fouad, S.S.; Sakr, G.B.; Yahia, I.S.; Abdel-Basset, D.M.; Yakuphanoglu, F.

    2014-01-01

    Graphical abstract: - Highlights: • XRD and DTA micrographs were used to study the structure of ZnGa{sub 2}Te{sub 4}. • C–V, G–V and R{sub s}–V of the diode characteristics have been analyzed for the first time. • Dielectric constant, dielectric loss, loss tangent and ac conductivity were determined. • The interfaces states were determined using conductance–voltage technique. • ZnGa{sub 2}Te{sub 4} is a good candidate for electronic device applications. - Abstract: Capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics of p-ZnGa{sub 2}Te{sub 4}/n-Si HJD were studied over a wide frequency and temperature. Both the interface states density N{sub ss} and series resistance R{sub s} were strongly frequency and temperature dependent. The interface states density N{sub ss} is decreased with increasing frequency and increase with increasing temperature. The values of the built-in potential (V{sub bi}) were calculated and found to increase with increasing temperature and frequency. The values of capacitance C, conductance G, series resistance R{sub s}, corrected capacitance C{sub ADJ}, corrected conductance G{sub ADJ}, dielectric constant (ε′), dielectric loss (ε″), loss tangent (tan δ) and the AC conductivity (σ{sub ac}) are strongly dependent on the applied frequency, voltage and temperature. The obtained results show that the locations of N{sub ss} and R{sub s} have a significant effect on the electrical characteristics of the studied diode.

  14. Solvent sensitive intramolecular charge transfer dynamics in the excited states of 4-N,N-dimethylamino-4'-nitrobiphenyl.

    PubMed

    Ghosh, Rajib; Nandi, Amitabha; Palit, Dipak K

    2016-03-21

    Organic molecules substituted with the nitro group show efficient nonlinear optical (NLO) properties, which are a consequence of the strong intramolecular charge transfer (ICT) character of the molecules because of the strong electron withdrawing nature of the nitro group and rapid responsiveness because of highly movable π-electrons. Dynamics of the ICT process in the excited states of a push-pull biphenyl derivative, namely, 4-N,N-dimethylamino-4'-nitrobiphenyl (DNBP), an efficient NLO material, has been investigated using ultrafast transient absorption spectroscopy. The experimental results have been corroborated with DFT and TDDFT calculations. In solvents of large polarity, e.g. acetonitrile, the ultrafast ICT process of DNBP is associated with the barrierless twisting of the N,N-dimethylaniline (DMA) group with respect to the nitrobenzene moiety to populate the twisted ICT (or TICT) state, and the rate of this process is solely governed by the viscosity of the medium. In solvents of moderate polarity, e.g. ethyl acetate, the rate of the twisting process is significantly slowed down and the LE and TICT states remain in equilibrium because of a low energy barrier for interconversion between these two states. By further lowering the polarity of the solvent, e.g. in dioxane, the twisting process is completely retarded. In nonpolar solvents, e.g. cyclohexane, a reverse twisting motion towards the planar geometry (i.e. the PICT process) has been evident in the excited state dynamics. In this solvent, the S1 state undergoes an ultrafast intersystem crossing to the triplet state because of its close proximity with the T2 state. PMID:26907751

  15. Magnetic properties of nanocrystalline ε-Fe{sub 3}N and Co{sub 4}N phases synthesized by newer precursor route

    SciTech Connect

    Theerthagiri, J.; Dalavi, Shankar B.; Manivel Raja, M.; Panda, R.N.

    2013-11-15

    Graphical abstract: Nanocrystalline ε-Fe{sub 3}N and Co{sub 4}N nitride phases are synthesized first time by newer chemical routes. The ε-Fe{sub 3}N phase crystallizes in hexagonal structure with unit cell parameters, a = 4.76 Å and c = 4.41 Å. The Co{sub 4}N phase crystallizes in face centred cubic (fcc) structure with unit cell parameters, a = 3.55 Å. The estimated crystallite size for ε-Fe{sub 3}N and Co{sub 4}N phases are 29 nm and 22 nm, respectively. The values of saturation magnetization for ε-Fe{sub 3}N and Co{sub 4}N phases are found to be 28.1 emu/g and 123.6 emu/g respectively. The reduction of magnetic moments in ultrafine materials compared to bulk materials has been explained by fine particle size and surface effects. We have synthesized the high moment ε-Fe{sub 3}N and Co{sub 4}N nitride with reduced coercivity which may find applications as soft magnetic materials. - Highlights: • Nanocrystalline ε-Fe{sub 3}N and Co{sub 4}N nitride phases are synthesized. • The ε-Fe{sub 3}N and Co{sub 4}N crystallizes in hexagonal and fcc structure respectively. • The observed magnetic parameters indicate soft magnetic properties. • The magnetic properties have been explained on the basis of fine particle magnetism. - Abstract: Nanocrystalline ε-Fe{sub 3}N and Co{sub 4}N nitride phases are synthesized first time by using tris(1,2-diaminoethane)iron(II) chloride and tris(1,2-diaminoethane)cobalt(III) chloride precursors, respectively. To prepare ε-Fe{sub 3}N and Co{sub 4}N nitride phases, the synthesized precursors were mixed with urea in 1:12 ratio and heat treated at various temperatures in the range of 450–900 °C under the ultrapure nitrogen gas atmosphere. The precursors are confirmed by FT-IR study. The ε-Fe{sub 3}N phase crystallizes in hexagonal structure with unit cell parameters, a = 4.76 Å and c = 4.41 Å. The Co{sub 4}N phase crystallizes in face centred cubic (fcc) structure with unit cell parameters, a = 3.55 Å. The

  16. Enhanced inverse spin-Hall voltage in (001) oriented Fe4N/Pt polycrystalline films without contribution of planar-Hall effect

    NASA Astrophysics Data System (ADS)

    Isogami, Shinji; Tsunoda, Masakiyo

    2016-04-01

    In this study, the output DC electric voltage (V out) generated by a Pt-capped Fe4N bilayer film (Fe4N/Pt) under ferromagnetic resonance conditions at room temperature was assessed. The contributions from the inverse spin-Hall effect (ISHE), the planar-Hall effect (PHE) and the anomalous-Hall effect (AHE) were separated from the output voltage by analysis of V out values determined at varying external field polar angles. The results showed that the polarity of the ISHE (V ISHE) component of V out was opposite to that of the PHE (V PHE). As a result, the magnitude of the intrinsic V ISHE was beyond V out by as much as the magnitude of V PHE. The X-ray diffraction structural analysis revealed the polycrystal of the Fe4N/Pt with (001) orientation, which might be one of the possible mechanisms for enhanced intrinsic V ISHE.

  17. Structural characterisation of human galectin-4 N-terminal carbohydrate recognition domain in complex with glycerol, lactose, 3′-sulfo-lactose, and 2′-fucosyllactose

    PubMed Central

    Bum-Erdene, Khuchtumur; Leffler, Hakon; Nilsson, Ulf J.; Blanchard, Helen

    2016-01-01

    Galectin-4 is a tandem-repeat galectin with two distinct carbohydrate recognition domains (CRD). Galectin-4 is expressed mainly in the alimentary tract and is proposed to function as a lipid raft and adherens junction stabilizer by its glycan cross-linking capacity. Galectin-4 plays divergent roles in cancer and inflammatory conditions, either promoting or inhibiting each disease progression, depending on the specific pathological condition. The study of galectin-4’s ligand-binding profile may help decipher its roles under specific conditions. Here we present the X-ray structures of human galectin-4 N-terminal CRD (galectin-4N) bound to different saccharide ligands. Galectin-4’s overall fold and its core interactions to lactose are similar to other galectin CRDs. Galectin-4N recognises the sulfate cap of 3′-sulfated glycans by a weak interaction through Arg45 and two water-mediated hydrogen bonds via Trp84 and Asn49. When galectin-4N interacts with the H-antigen mimic, 2′-fucosyllactose, an interaction is formed between the ring oxygen of fucose and Arg45. The extended binding site of galectin-4N may not be well suited to the A/B-antigen determinants, α-GalNAc/α-Gal, specifically due to clashes with residue Phe47. Overall, galectin-4N favours sulfated glycans whilst galectin-4C prefers blood group determinants. However, the two CRDs of galectin-4 can, to a less extent, recognise each other’s ligands. PMID:26828567

  18. K-Ar dating and delta O-18-delta D characterization of nanometric illite from Ordovician K-bentonites of the Appalachians: illitization and the Acadian-Alleghenian tectonic activity

    USGS Publications Warehouse

    Clauer, Norbert; Fallick, Anthony E.; Eberl, Dennis D.; Honty, Miroslav; Huff, Warren D.; Auberti, Amelie

    2013-01-01

    Nanometric (2 diagram that illitization occurred in all fractions by simultaneous nucleation and crystal growth, except for one sample. In that sample, a period of growth without nucleation was detected on top of the nucleation and growth episode. The K-Ar ages organize into two isochrons, the first at 319.9 ± 2.0 Ma with an initial 40Ar/36Ar ratio of 271 ± 66 Ma, and the second at 284.9 ± 1.2 Ma with an initial 40Ar/36Ar ratio of 310 ± 44. One data point above the older isochron and three between the two isochrons suggest a detrital contamination for the former separate and a possible further generation of nanoparticles for the three others. The samples with the older crystallization age consist of illite and illite-rich mixed-layers, and those with the younger age contain smectite-rich mixed-layers without illite, or illite-enriched illite-smectite mixed-layers. The K-Ar ages fit the age trends published previously for similar K-bentonites with regional age patterns between 240 and 270 Ma in the southwestern region, between 270 and 300 Ma in the central zone and the southern Appalachians, and between 315 and 370 Ma in the northernmost. Each of the two generations of illite crystals yields very consistent δ18O (V-SMOW) values at 17 ± 1‰ for the older and at 21 ± 1‰ for the younger. If crystallization temperatures of the nanometric illite were between 100 and 200 °C, as suggested by microthermometric determinations, the hydrothermal fluids had δ18O values of 4 ± 1‰ in the Dalton district and of 8 ± 1‰ in the Lafayette, Trenton, and Dirtseller districts at 100 °C, and of 11 ± 1 and 15 ± 1‰ in the same locations at 200 °C, probably because the water-rock isotope exchanges at elevated temperature occurred in rock-dominated systems. The δ18O of the fluids remained unchanged during local crystal growth, but varied depending on the geographic location of the samples and timing of illitization. The δD (V-SMOW) values of the different size

  19. Diffusion bonding of the oxide dispersion strengthened steel PM2000

    NASA Astrophysics Data System (ADS)

    Sittel, Wiebke; Basuki, Widodo W.; Aktaa, Jarir

    2013-11-01

    Ferritic oxide dispersion strengthened (ODS) steels are well suited as structural materials, e.g. for claddings in fission reactors and for plasma facing components in fusion power plants due to their high mechanical and oxidation stability at high temperatures and their high irradiation resistance. PM2000 is an iron based ODS ferritic steel with homogeneously distributed nanometric yttria particles. Melting joining techniques are not suitable for such ODS materials because of the precipitation and agglomeration of the oxide particles and hence the loss of their strengthening effect. Solid state diffusion bonding is thus chosen to join PM2000 and is investigated in this work with a focus on oxide particles. The diffusion bonding process is aided by the computational modeling, including the influence of the ODS particles. For modeling the microstructure stability and the creep behavior of PM2000 at various, diffusion bonding relevant temperatures (50-80% Tm) are investigated. Particle distribution (TEM), strength (tensile test) and toughness (Charpy impact test) obtained at temperatures relevant for bonding serve as input for the prediction of optimal diffusion bonding parameters. The optimally bonded specimens show comparable strength and toughness relative to the base material.

  20. On the mechanism of photochromism of 4'-N,N-dimethylamino-7-hydroxyflavylium in pluronic F127.

    PubMed

    Gomes, Raquel; Laia, César A T; Pina, Fernando

    2009-08-13

    The photochromism of the compound 4'-N,N-dimethylamino-7-hydroxyflavylium incorporated in Pluronic F127 micelles and gels was studied in great detail. The red flavylium ion (AH(+)) or the quinoidal base (A), depending on pH, are the irradiation products of the colorless trans-chalcone (Ct). Absorption and fluorescence (steady-state, time-resolved, and anisotropy), pH jumps, and flash photolysis were used to characterize the system. At moderately acidic to neutral pH values, the Ct species is distributed between the core and corona of the Pluronic micelle, as well as in the aqueous phase. At acidic pH values, AH(+) remains most probably in the water phase. The Ct maximum absorption wavelength constitutes a good sensor for the critical micelle concentration (CMC) or critical micelle temperature (CMT). The apparent acidity constant pK'(a) was found to be a relatively good sensor for CMC and also for detection of the sol-gel critical temperature. The Ct photochromic mechanism was analyzed by comparing the photophysics in pure solvents and the pluronic media. Solvatochromic effects show a lack of solvent polarity dependence of the Stokes shift, indicating a low dipolar moment change between the ground and the locally excited state. An internal charge transfer nonradiative process (ICT) competes with Ct photoisomerization and is the dominant process in highly polar solvents, preventing the appearance of photochromism, in contrast with lower polar environments, such as micelles and ethanol. In high viscous environments as those found in the core of the Pluronic F127 micelles or glycerol, both ICT and photoisomerization are reduced, enhancing the Ct fluorescence quantum yield. According to the data from fluorescence measurements and pH jumps, evidence for the Ct distribution among different sites within the pluronic aggregate was found, (i) a hydrophilic/fluid region where Ct has poor fluorescence and isomerization yields, bulk region; (ii) the corona of the micelle where

  1. Characteristics of urban-ecosystem atmosphere fluxes of CO2, CH4, N2O, and et over Denver, Colorado

    USGS Publications Warehouse

    Anderson, D.E.; Alvarez, C.; Thienelt, T.

    2004-01-01

    The characteristics of urban ecosystems fluxes of carbon dioxide, methane, nitrous oxide, and evapotranspiration (ET) over Denver, Colorado were discussed. These atmospheric fluxes were measured using a methodology that included a combination of eddy covariance sensors at two levels on a tall tower and chamber measurements at 33 locations on the soil surface. There was both strong temporal and spatial heterogeneity of fluxes owing to characteristics of natural and anthropogenic ecosystem components. Although the urban ecosystem was a net carbon dioxide source, tower-based eddy covariance measurements showed it to be a net vegetative sink during the majority of mid-say summer hours.

  2. Phenylthiolate as a sigma- and pi- donor ligand: synthesis of a 3-D organometallic coordination polymer [K2Fe(SPh)4]n.

    PubMed

    Yu, Xiao-Yan; Jin, Guo-Xin; Weng, Lin-Hong

    2004-07-01

    The synthesis and crystal structure of the first mixed-metal organometallic polymer network containing phenylthiolato ligands, [K2Fe(SPh)4]n, are investigated. The simple phenylthiolate acts as a sigma- and pi-donor ligand to give a 3-D potassium iron coordination polymer with both metal-carbon and metal-sulfur coordination interactions.

  3. Inversion of exchange bias and complex magnetization reversal in full-nitride epitaxial γ‧-Fe4N/CoN bilayers

    NASA Astrophysics Data System (ADS)

    Li, Z. R.; Mi, W. B.; Wang, X. C.; Bai, H. L.

    2015-04-01

    Exchange bias has been observed in the full-nitride epitaxial γ‧-Fe4N/CoN bilayers. With the increase of temperature, the sign of exchange bias (EB) is inverse, which is independent on the cooling field and training effect. This novel behavior appears in the bilayers with different CoN and γ‧-Fe4N thicknesses. The inversion of EB sign not only occurs at low temperatures, but also takes place even at 200 K for the 10 and 12 nm thick CoN layer. With the decreased γ‧-Fe4N layer thickness, the inversion temperature of EB sign shows a roughly increased tendency. For the bilayer with a 4 nm-thick γ‧-Fe4N, the interfacial magnetization reversal presents a complex trend, which is considered as the combined actions of the disordered ferromagnetic spins and various competed magnetic structures. This new manifestation of EB has been discussed in terms of the complicated interfacial spin structures and frustration effects due to the competition between the ferromagnetic and antiferromagnetic exchange interactions at the interface.

  4. Development of ferret as a human lung cancer model by injecting4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Development of new animal lung cancer models that are relevant to human lung carcinogenesis is important for lung cancer research. Previously we have shown the induction of lung tumor in ferrets (Mustela putorius furo) exposed to both tobacco smoke and a tobacco carcinogen (4-(N-methyl-N-nitrosamino...

  5. Revealing the local properties of β-HP4N7, a promising candidate for high pressure synthesis of new materials

    NASA Astrophysics Data System (ADS)

    Morales-García, A.; del Corro, E.

    2015-04-01

    A computational investigation of β-HP4N7 system is accurately performed using the density functional theory formalism coupled with quantum theory of atoms in molecules. The aim of this work is to understand the behavior of β-HP4N7 under compression. At ambient conditions, the N atoms occupy around 81% of the unit cell volume; for this reason the N atoms are the ones contributing significantly to the bulk properties. The particular tetrahedron (PN4) connection promotes high flexibility to this structure. The atoms composing the solid show significant differences in their compressibilities. The high compressibility (or low resistence to pressure) of the N atoms indicates that the reorganization of these atoms is the key in the densification process that takes place when pressure is increased. When compresing the β-HP4N7 from 0 to 130 GPa the formation of PN6 units is observed, leading to a phase transition. The analysis of the elastic constants reveals the stability of this new phase at 110 GPa. This study shows that β-HP4N7 could be a potential candidate for high pressure synthesis of new phases where P atoms would be 6-fold coordinated.

  6. The Scope of Direct Alkylation of Gold Surface with Solutions of C1–C4n-Alkylstannanes

    PubMed Central

    2015-01-01

    Treatment of cleaned gold surfaces with dilute tetrahydrofuran or chloroform solutions of tetraalkylstannanes (alkyl = methyl, ethyl, n-propyl, n-butyl) or di-n-butylmethylstannyl tosylate under ambient conditions causes a self-limited growth of disordered monolayers consisting of alkyls and tin oxide. Extensive use of deuterium labeling showed that the alkyls originate from the stannane and not from ambient impurities, and that trialkylstannyl groups are absent in the monolayers, contrary to previous proposals. Methyl groups attached to the Sn atom are not transferred to the surface. Ethyl groups are transferred slowly, and propyl and butyl rapidly. In all cases, tin oxide is codeposited in submonolayer amounts. The monolayers were characterized by ellipsometry, contact angle goniometry, polarization modulated IR reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy with ferrocyanide/ferricyanide, which revealed a very low charge-transfer resistance. The thermal stability of the monolayers and their resistance to solvents are comparable with those of an n-octadecanethiol monolayer. A preliminary examination of the kinetics of monolayer deposition from a THF solution of tetra-n-butylstannane revealed an approximately half-order dependence on the bulk solution concentration of the stannane, hinting that more than one alkyl can be transferred from a single stannane molecule. A detailed structure of the attachment of the alkyl groups is not known, and it is proposed that it involves direct single or multiple bonding of one or more C atoms to one or more Au atoms. PMID:26327466

  7. Plasticity and ab initio characterizations on Fe 4N produced on the surface of nanocrystallized 18Ni-maraging steel plasma nitrided at lower temperature

    NASA Astrophysics Data System (ADS)

    Yan, M. F.; Wu, Y. Q.; Liu, R. L.

    2009-08-01

    18Ni-maraging steel has been entirely nanocrystallized by a series of processes including solution treatment, hot-rolling deformation, cold-drawn deformation and direct electric heating. The plasma nitriding of nanocrystallized 18Ni-maraging steel was carried out at 410 °C for 3 h and 6 h in a mixture gas of 20% N 2 + 80% H 2 with a pressure of 400 Pa. The surface phase constructions and nitrogen concentration profile in surface layer were analyzed using an X-ray diffractometer (XRD) and the glow discharge spectrometry (GDS), respectively. The results show that an about 2 μm thick compound layer (mono-phase γ'-Fe 4N) can be produced on the top of the surface layer of nanocrystallized 18Ni-maraging steel plasma nitrided at 410 °C for 6 h. The measured hardness value of the nitrided surface is 11.6 GPa. More importantly, the γ'-Fe 4N phase has better plasticity, i.e., its plastic deformation energy calculated from the load-displacement curve obtained by nano-indentation tester is close to that of nanocrystallized 18Ni-maraging steel. Additionally, the mechanical properties of γ'-Fe 4N phase were also characterized by first-principles calculations. The calculated results indicate that the hardness value and the ratio of bulk to shear modulus ( B/ G) of the γ'-Fe 4N phase are 10.15 GPa and 3.12 (>1.75), respectively. This demonstrates that the γ'-Fe 4N phase has higher hardness and better ductility.

  8. Radiative effects of CH4, N2O, halocarbons and the foreign-broadened H2O continuum: A GCM experiment

    NASA Astrophysics Data System (ADS)

    Schwarzkopf, M. Daniel; Ramaswamy, V.

    1999-04-01

    The simplified exchange approximation (SEA) method for calculation of infrared radiative transfer, used for general circulation model (GCM) climate simulations at the Geophysical Fluid Dynamics Laboratory (GFDL) and other institutions, has been updated to permit inclusion of the effects of methane (CH4), nitrous oxide (N2O), halocarbons, and water-vapor-air molecular broadening (foreign broadening). The effects of CH4 and N2O are incorporated by interpolation of line-by-line (LBL) transmissivity calculations evaluated at standard species concentrations; halocarbon effects are calculated from transmissivities computed using recently measured frequency-dependent absorption coefficients. The effects of foreign broadening are included by adoption of the "CKD" formalism for the water vapor continuum [Clough et al., 1989]. For a standard midlatitude summer profile, the change in the net infrared flux at the model tropopause due to the inclusion of present-day concentrations of CH4 and N2O is evaluated to within ˜5% of corresponding LBL results; the change in net flux at the tropopause upon inclusion of 1 ppbv of CFC-11, CFC-12, CFC-113, and HCFC-22 is within ˜10% of the LBL results. Tropospheric heating rate changes resulting from the introduction of trace species (CH4, N2O, and halocarbons) are calculated to within ˜0.03 K/d of the LBL results. Introduction of the CKD water vapor continuum causes LBL-computed heating rates to decrease by up to ˜0.4 K/d in the upper troposphere and to increase by up to ˜0.25 K/d in the midtroposphere; the SEA method gives changes within ˜0.05 K/d of the LBL values. The revised SEA formulation has been incorporated into the GFDL "SKYHI" GCM. Two simulations (using fixed sea surface temperatures and prescribed clouds) have been performed to determine the changes to the model climate from that of a control calculation upon inclusion of (1) the trace species and (2) the foreign-broadened water vapor continuum. When the trace species

  9. Assessment of efficacy, safety, and tolerability of 4-n-butylresorcinol 0.3% cream: an Indian multicentric study on melasma

    PubMed Central

    Madan Mohan, NT; Gowda, Adarsh; Jaiswal, Ashok Kumar; Sharath Kumar, BC; Shilpashree, P; Gangaboraiah, Bilugumba; Shamanna, Manjula

    2016-01-01

    Introduction Melasma is one of the commonly reported pigmentory disorders in the Indian population. Numerous therapeutic modalities are available. However, very few have produced complete satisfactory response. 4-n-Butylresorcinol 0.3% cream has recently been introduced in India as a new hypopigmenting agent. It is a resorcinol derivative and acts by inhibiting both tyrosinase and tyrosinase-related protein-1. Objective The available published literatures are with 4-n-butylresorcinol 0.1% cream, and there is paucity of clinical studies with 4-n-butylresorcinol 0.3% cream. Furthermore, considering the fact that Indian skin is more prone to irritation with hypopigmenting agents, our study explores the efficacy, safety, and tolerability of 4-n-butylresorcinol 0.3% cream in Indian subjects with melasma. Methods Fifty-two subjects with melasma participated in this open-label, single arm, observational study. All the patients were advised twice daily application of 4-n-butylresorcinol 0.3% cream for 8 weeks over the areas of melasma. Assessment parameters included modified Melasma Area Severity Index (mMASI) score. Digital photographs of all the patients at baseline, week 4, and week 8 were taken. During this 8-week study period, all the adverse events were observed and recorded. Results All the 52 subjects completed the study. Out of 52 subjects, 90.38% were females. The mean age of patients was 38.5±7.8 years. Mean ± standard error of MASI score measurements showed a significant decrease from baseline score of 14.73±0.59 to 11.09±0.53 after week 4 (P<0.001) and 6.48±0.43 at week 8 (P<0.001). The digital photographs of the study subjects taken at week 4 and week 8 also showed decrease in melasma pigmentation compared to baseline photograph and correlated with the changes in the mMASI score. The treatment was well tolerated by all the study subjects. No adverse reactions were reported throughout the study period. Conclusion Our data suggest that the 4-n

  10. Perpendicular magnetic anisotropy of Mn{sub 4}N films on MgO(001) and SrTiO{sub 3}(001) substrates

    SciTech Connect

    Yasutomi, Yoko; Ito, Keita; Sanai, Tatsunori; Toko, Kaoru; Suemasu, Takashi

    2014-05-07

    We grew Mn{sub 4}N epitaxial thin films capped with Au layers on MgO(001) and SrTiO{sub 3}(001) substrates by molecular beam epitaxy. Perpendicular magnetic anisotropy (PMA) was confirmed in all the samples at room temperature from the magnetization versus magnetic field curves using superconducting quantum interference device magnetometer. From the ω-2θ x-ray diffraction (XRD) and ϕ-2θ{sub χ} XRD patterns, the ratios of perpendicular lattice constant c to in-plane lattice constant a, c/a, were found to be about 0.99 for all the samples. These results imply that PMA is attributed to the in-plane tensile strain in the Mn{sub 4}N films.

  11. Photo-assisted local oxidation of GaN using an atomic force microscope

    NASA Astrophysics Data System (ADS)

    Hwang, Jih Shang; Shuo Hu, Zhan; Lu, Ton Yuan; Chen, Li Wei; Chen, Shi Wei; Lin, Tai Yuan; Hsiao, Ching-Lien; Chen, Kuei-Hsien; Chen, Li-Chyong

    2006-07-01

    This paper introduces a photo-assisted atomic force microscope (AFM) local oxidation technique which is capable of producing highly smooth oxide patterns with heights reaching several tens of nanometres on both n- and p-types of GaN (and in principle on most semiconductors) without the use of chemicals. The novel methodology relies on UV illumination of the surface of the substrate during conventional AFM local oxidation. A low 1.2 V threshold voltage for n-type GaN was obtained, which can be explained by UV photo-generation of excess electron-hole pairs in the substrate near the junction, thereby reducing the electric field required to drive carrier flow through the tip-sample Schottky barrier. It was demonstrated that the presence or absence of light alone was sufficient to switch the growth of the oxide on or off. The photo-assisted AFM oxidation technique is of immediate interest to the semiconductor industry for the fabrication of GaN-based complementary metal-oxide-semiconductor devices and nanodevices, improves chances for AFM-type data storage, and presents new degrees of freedom for process control technique.

  12. The first quaternary lanthanide(III) nitride iodides: NaM{sub 4}N{sub 2}I{sub 7} (M=La-Nd)

    SciTech Connect

    Schurz, Christian M.; Schleid, Thomas

    2010-10-15

    In attempts to synthesize lanthanide(III) nitride iodides with the formula M{sub 2}NI{sub 3} (M=La-Nd), moisture-sensitive single crystals of the first quaternary sodium lanthanide(III) nitride iodides NaM{sub 4}N{sub 2}I{sub 7} (orthorhombic, Pna2{sub 1}; Z=4; a=1391-1401, b=1086-1094, c=1186-1211 pm) could be obtained. The dominating structural features are {sup 1}{sub {infinity}}{l_brace}[NM{sub 4/2}{sup e}]{sup 3+}{r_brace} chains of trans-edge linked [NM{sub 4}]{sup 9+} tetrahedra, which run parallel to the polar 2{sub 1}-axis [001]. Between the chains, direct bonding via special iodide anions generates cages, in which isolated [NaI{sub 6}]{sup 5-} octahedra are embedded. The IR spectrum of NaLa{sub 4}N{sub 2}I{sub 7} recorded from 100 to 1000 cm{sup -1} shows main bands at {upsilon}=337, 373 and 489 cm{sup -1}. With decreasing radii of the lanthanide trications these bands, which can be assigned as an influence of the vibrations of the condensed [NM{sub 4}]{sup 9+} tetrahedra, are shifted toward higher frequencies for the NaM{sub 4}N{sub 2}I{sub 7} series (M=La-Nd), following the lanthanide contraction. - Abstract: View at the main structural features of the NaM{sub 4}N{sub 2}I{sub 7} series (M=La-Nd): The {sup 1}{sub {infinity}}{l_brace}[NM{sub 4/2}{sup e}]{sup 3+}{r_brace} chains, consisting of trans-edge connected [NM{sub 4}]{sup 9+} tetrahedra, and the special kind of iodide anions, namely (I7){sup -}, form cages, in which isolated [NaI{sub 6}]{sup 5-} octahedra are embedded.

  13. [Seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value in rainwater in Yangtze River Delta].

    PubMed

    Xie, Ying-Xin; Zhang, Shu-Li; Zhao, Xu; Xiong, Zheng-Qin; Xing, Guang-Xi

    2008-09-01

    By using a customized manual rainwater sampler made of polyvinyl chloride plastic, the molar ratio of NH4(+) -N/NO3(-) -N and the natural 15N abundance of NH4(+) (delta 15 NH4(+) in rainwater was monitored all year round from June 2003 to July 2005 at three observation sites (Changshu, Nanjing, and Hangzhou) in the Yangtze River Delta. The results indicated that at the three sites, the NH4(+) -N/NO3(-) -N ratio and the delta 15 NH4(+) value in rainwater had the similar seasonal variation trend, being more obvious in Changshu (rural monitoring type) site than in Nanjing (urban monitoring type) and Hangzhou (urban-rural monitoring type) sites. The NH4(+) -N/NO3(-) -N ratio peaked from early June to early August, declined gradually afterwards, and reached the bottom in winter; while the delta 15 NH4(+) value was negative from late June to mid-August, turned positive from late August to mid or late November, became negative again when winter dominated from December to March, but turned positive again in next May and negative again in next July. These seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value were found in relation to the application of chemical nitrogen fertilizers during different crop growth periods, and also, the alternation of seasons and the NH3 volatilization from other NH3 emission sources (including excrements of human and animals, nitrogen- polluted water bodies, and organic nitrogen sources, etc.), which could be taken as an indicator of defining the sources and form composition of NH4(+) in atmospheric wet deposition and the intensity of various terrestrial NH3 emission sources.

  14. Synthesis and characterization of a cadmium bipyridinium compound (CdCl{sub 4})(N,N'-dimethyl-2,2'-bipyridinium)

    SciTech Connect

    Luo, Hui; Zhu, Li-Cheng; Wang, Qi

    2015-12-15

    A cadmium bipyridinium compound (CdCl{sub 4})(N,N'-dimethyl-2,2'-bipyridinium), in which the (N,N'-dimethyl-2,2'-bipyridinium){sup 2+} moieties were generated in situ, has been prepared via solvothermal reactions and structurally characterized with single crystal X-ray diffraction method. Fluorescence measurement revealed a broad and strong emission band in the blue region.

  15. Synthesis and evaluation of substituted 4-(N-benzylamino)cinnamate esters as potential anti-cancer agents and HIV-1 integrase inhibitors.

    PubMed

    Faridoon; Edkins, Adrienne L; Isaacs, Michelle; Mnkandhla, Dumisani; Hoppe, Heinrich C; Kaye, Perry T

    2016-08-01

    Encouraging selectivity and low micromolar activity against HeLa cervical carcinoma (IC50⩾3.0μM) and the aggressive MDA-MB-231 triple negative breast carcinoma (IC50⩾9.6μM) cell lines has been exhibited by a number of readily accessible 4-(N-benzylamino)cinnamate esters. The potential of the ligands as HIV-1 integrase inhibitors has also been examined. PMID:27317645

  16. Pharmacological stress is required for the anti-alcohol effect of the α3β4* nAChR partial agonist AT-1001.

    PubMed

    Cippitelli, Andrea; Brunori, Gloria; Gaiolini, Kelly A; Zaveri, Nurulain T; Toll, Lawrence

    2015-06-01

    Alcohol and nicotine are often taken together. The mechanisms underlying this frequent co-abuse are not well known. Genetic and pharmacological evidence suggests that the nicotinic acetylcholine receptors (nAChRs) containing the α3 and β4 subunits play a role in alcohol as well as nicotine addiction. AT-1001 is a high affinity α3β4 nAChR partial agonist recently found to block nicotine self-administration and relapse-like behavior in rats. Here, to study the involvement of α3β4 nAChRs in the mechanisms that regulate alcohol abuse we evaluated the effects of AT-1001 on alcohol taking and seeking in Sprague-Dawley rats. AT-1001 reduced operant alcohol self-administration at the highest dose examined (3.0 mg/kg), an effect also observed for food self-administration. A dose of 1.5 mg/kg AT-1001, which had no effect on alcohol or food self-administration, essentially eliminated reinstatement of alcohol seeking induced by yohimbine (0.625 mg/kg) whereas, reinstatement induced by alcohol-associated cues was not altered, nor did AT-1001 induce reinstatement of extinguished self-administration on its own. Finally, AT-1001 showed an anxiolytic activity when measured in the presence or absence of yohimbine stress in the elevated plus maze paradigm. Together, these observations do not support a specific involvement of the α3β4 nAChR in mediating alcohol reward or cue-induced relapse to alcohol seeking but rather indicate that the α3β4 nAChR partial agonism may constitute an attractive approach for treating alcohol use disorders exacerbated by elevated stress response.

  17. High capacity and superlong cycle life of Li3VO4/N-C hybrids as anode for high performance Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Jicheng; Ni, Shibing; Ma, Jianjun; Yang, Xuelin; Zhang, Lulu

    2016-01-01

    High capacity and superlong cycle life of Li3VO4 have been actualized via carbon hybridization and N doping. The Li3VO4/N doped C (Li3VO4/N-C) that fabricated via an in situ carbonization method based on an intermedial solution phase delivers initial discharge and charge capacities of 686 and 540 mAh g-1 at a specific current of 0.15 A g-1, which maintain of 538 and 536 mAh g-1 after 800 cycles, showing excellent cycle stability. Meanwhile, the Li3VO4/N-C exhibits superior rate performance and long life performance. After 150 cycles at various specific currents from 0.1 to 2.0 A g-1, the discharge and charge capacities can restore 100% when reverting the specific current to 0.1 A g-1. After 1100 cycles at a specific current of 2.0 A g-1, the discharge and charge capacities can maintain of 340 and 337 mAh g-1, showing no capacity attenuation in cycling.

  18. Role of nitrogen in the formation of HC-N films by CH(4)/N(2) barrier discharge plasma: aliphatic tendency.

    PubMed

    Majumdar, Abhijit; Das, Gobind; Basvani, Kaleswara Rao; Heinicke, Joachim; Hippler, Rainer

    2009-12-01

    We have studied the influence of nitrogen on the chemical properties of the hydrogenated carbon nitride (a-CN(x):H) film deposited by CH(4)/N(2) dielectric barrier discharge (DBD) plasma. X-ray photoelectron spectroscopy (XPS) indicates that carbon and nitrogen form an unpolarized covalent bond in these C-N(x) materials, and the observed chemical shift in the C 1s and N 1s binding energy is explained with respect to N 1s incorporation. Furthermore, the average nitrogen content (N/C approximately 0.76) in the films was systematically varied by changing the nitrogen partial pressure (CH(4)/N(2) approximately from 5:1 to 1:7) which is well supported by the elemental analysis. Fourier transform infrared (FTIR) absorption spectra exhibit significant changes in different C-N, C identical withN, and NH/OH molecular bands at higher nitrogen concentration in the film. The isonitrile and nitrile groups (-NC and -CN) are increased with the increase of deposition time. In addition, the elemental analysis, proton NMR, and thermolysis mass spectrum show that the composition of the film with the ratio CH(4)/N(2) approximately 1:1 is C, 67.68; H, 9.88; N, 16.53 (in wt %) and that the film is composed of polymers, probably containing linear chains which are cleaved off on heating in vacuum. PMID:19894689

  19. Coexistence of Three Ferroic Orders in the Multiferroic Compound [(CH3 )4 N][Mn(N3 )3 ] with Perovskite-Like Structure.

    PubMed

    Gómez-Aguirre, L Claudia; Pato-Doldán, Breogán; Stroppa, Alessandro; Yang, Li-Ming; Frauenheim, Thomas; Mira, Jorge; Yáñez-Vilar, Susana; Artiaga, Ramón; Castro-García, Socorro; Sánchez-Andújar, Manuel; Señarís-Rodríguez, María Antonia

    2016-06-01

    The perovskite azido compound [(CH3 )4 N][Mn(N3 )3 ], which undergoes a first-order phase change at Tt =310 K with an associated magnetic bistability, was revisited in the search for additional ferroic orders. The driving force for such structural transition is multifold and involves a peculiar cooperative rotation of the [MnN6 ] octahedral as well as order/disorder and off-center shifts of the [(CH3 )4 N](+) cations and bridging azide ligands, which also bend and change their coordination mode. According to DFT calculations the latter two give rise to the appearance of electric dipoles in the low-temperature (LT) polymorph, the polarization of which nevertheless cancels out due to their antiparallel alignment in the crystal. The conversion of this antiferroelectric phase to the paraelectric phase could be responsible for the experimental dielectric anomaly detected at 310 K. Additionally, the structural change involves a ferroelastic phase transition, whereby the LT polymorph exhibits an unusual and anisotropic thermal behavior. Hence, [(CH3 )4 N][Mn(N3 )3 ] is a singular material in which three ferroic orders coexist even above room temperature. PMID:27072487

  20. Structural and magnetic properties of ferrimagnetic ε-phase Mn4N and antiferromagnetic ζ-phase Mn10N thin films on MgO(001)

    NASA Astrophysics Data System (ADS)

    Foley, Andrew; Corbett, Joseph; Richard, Andrea L.; Alam, Khan; Ingram, David C.; Smith, Arthur R.

    2016-07-01

    Single phase ε-Mn4N and ζ-Mn10N thin films are grown on MgO(001) using molecular beam epitaxy. The films are identified and characterized using reflection high-energy electron diffraction, x-ray diffraction, back scattered electron scanning electron microscopy, atomic/magnetic force microscopy and Rutherford backscattering spectrometry. These films are found to be highly smooth with root-mean-squared roughnesses 3.39 nm and below. The quality of ε-Mn4N grown is strongly dependent on substrate temperature during growth. Epitaxial growth of substantial grains composed of the antiferromagnetic η-phase Mn3N2 side by side with ferrimagnetic ε-phase grains is observed when growth temperature is below 480 °C. Ising domains isolated within areas roughly 0.5 μm across are observed in the ferrimagnetic ε-phase grains of samples consisting of a mix of η- and ε-phase grains. Magnetic domains following semi-continuous paths, which are 0.7-7.2 μm across, are observed in single phase ε-Mn4N. Measurements of the ζ-phase detail the structure and magnetism of the material as high Mn content γ-type ζ-phase with a regular surface corrugation along the [100]-direction and antiferromagnetic.

  1. Spectroscopic studies of non-volatile residue formed by photochemistry of solid C4N2: A model of condensed aerosol formation on Titan

    NASA Astrophysics Data System (ADS)

    Couturier-Tamburelli, Isabelle; Gudipati, Murthy S.; Lignell, Antti; Jacovi, Ronen; Piétri, Nathalie

    2014-05-01

    Following our recent communication (Gudipati, M.S. et al. [2013]. Nat. Commun. 4, 1648. http://dx.doi.org/10.1038/ncomms2649) on the discovery of condensed-phase non-volatile polymeric material with similar spectral features as tholins, we present here a comprehensive spectroscopic study of photochemical formation of polymeric material from condensed dicyanoacetylene (C4N2) ice films. C4N2 is chosen as starting material for the laboratory simulations because of the detection of this and similar molecules (nitriles and cyanoacetylenes) in Titan’s atmosphere. UV-Vis and infrared spectra obtained during long-wavelength (>300 nm) photon irradiation and subsequent warming of the ice films are used to analyze changes in C4N2 ice, evolution of tholins, and derive photopolymerization mechanisms. Our data analysis revealed that many processes occur during the photolysis of condensed Titan’s aerosol analogs, including isomerization and polymerization leading to the formation of long-chain as well as aromatic cyclic polymer molecules. In the light of tremendous new data from the Cassini mission on the seasonal variations in Titan’s atmosphere, our laboratory study and its results provide fresh insight into the formation and evolution of aerosols and haze in Titan’s atmosphere.

  2. Calculation of the thermal conductivity of low-density CH4-N2 gas mixtures using an improved kinetic theory approach.

    PubMed

    Hellmann, Robert; Bich, Eckard; Vesovic, Velisa

    2016-04-01

    The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Z(rot), for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter. PMID:27059564

  3. Local electronic states of Fe{sub 4}N films revealed by x-ray absorption spectroscopy and x-ray magnetic circular dichroism

    SciTech Connect

    Ito, Keita; Toko, Kaoru; Suemasu, Takashi; Takeda, Yukiharu; Saitoh, Yuji; Oguchi, Tamio; Kimura, Akio

    2015-05-21

    We performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at Fe L{sub 2,3} and N K-edges for Fe{sub 4}N epitaxial films grown by molecular beam epitaxy. In order to clarify the element specific local electronic structure of Fe{sub 4}N, we compared experimentally obtained XAS and XMCD spectra with those simulated by a combination of a first-principles calculation and Fermi's golden rule. We revealed that the shoulders observed at Fe L{sub 2,3}-edges in the XAS and XMCD spectra were due to the electric dipole transition from the Fe 2p core-level to the hybridization state generated by σ* anti-bonding between the orbitals of N 2p at the body-centered site and Fe 3d on the face-centered (II) sites. Thus, the observed shoulders were attributed to the local electronic structure of Fe atoms at II sites. As to the N K-edge, the line shape of the obtained spectra was explained by the dipole transition from the N 1s core-level to the hybridization state formed by π* and σ* anti-bondings between the Fe 3d and N 2p orbitals. This hybridization plays an important role in featuring the electronic structures and physical properties of Fe{sub 4}N.

  4. Calculation of the thermal conductivity of low-density CH4-N2 gas mixtures using an improved kinetic theory approach.

    PubMed

    Hellmann, Robert; Bich, Eckard; Vesovic, Velisa

    2016-04-01

    The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Z(rot), for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter.

  5. Calculation of the thermal conductivity of low-density CH4-N2 gas mixtures using an improved kinetic theory approach

    NASA Astrophysics Data System (ADS)

    Hellmann, Robert; Bich, Eckard; Vesovic, Velisa

    2016-04-01

    The thermal conductivity of low-density CH4-N2 gas mixtures has been calculated by means of the classical trajectory method using state-of-the-art intermolecular potential energy surfaces for the CH4-CH4, N2-N2, and CH4-N2 interactions. Results are reported in the temperature range from 70 K to 1200 K. Since the thermal conductivity is influenced by the vibrational degrees of freedom of the molecules, which are not included in the rigid-rotor classical trajectory computations, a new correction scheme to account for vibrational degrees of freedom in a dilute gas mixture is presented. The calculations show that the vibrational contribution at the highest temperature studied amounts to 46% of the total thermal conductivity of an equimolar mixture compared to 13% for pure nitrogen and 58% for pure methane. The agreement with the available experimental thermal conductivity data at room temperature is good, within ±1.4%, whereas at higher temperatures, larger deviations up to 4.5% are observed, which can be tentatively attributed to deteriorating performance of the measuring technique employed. Results are also reported for the magnitude and temperature dependence of the rotational collision number, Zrot, for CH4 relaxing in collisions with N2 and for N2 relaxing in collisions with CH4. Both collision numbers increase with temperature, with the former being consistently about twice the value of the latter.

  6. Synthetic precursors for TCNQF4(2-) compounds: synthesis, characterization, and electrochemical studies of (Pr4N)2TCNQF4 and Li2TCNQF4.

    PubMed

    Lu, Jinzhen; Le, Thanh Hai; Traore, Daouda A K; Wilce, Matthew; Bond, Alan M; Martin, Lisandra L

    2012-12-01

    Careful control of the reaction stoichiometry and conditions enables the synthesis of both LiTCNQF(4) and Li(2)TCNQF(4) to be achieved. Reaction of LiI with TCNQF(4), in a 4:1 molar ratio, in boiling acetonitrile yields Li(2)TCNQF(4). However, deviation from this ratio or the reaction temperature gives either LiTCNQF(4) or a mixture of Li(2)TCNQF(4) and LiTCNQF(4). This is the first report of the large-scale chemical synthesis of Li(2)TCNQF(4). Attempts to prepare a single crystal of Li(2)TCNQF(4) have been unsuccessful, although air-stable (Pr(4)N)(2)TCNQF(4) was obtained by mixing Pr(4)NBr with Li(2)TCNQF(4) in aqueous solution. Pr(4)NTCNQF(4) was also obtained by reaction of LiTCNQF(4) with Pr(4)NBr in water. Li(2)TCNQF(4), (Pr(4)N)(2)TCNQF(4), and Pr(4)NTCNQF(4) have been characterized by UV-vis, FT-IR, Raman, and NMR spectroscopy, high resolution electrospray ionization mass spectrometry, and electrochemistry. The structures of single crystals of (Pr(4)N)(2)TCNQF(4) and Pr(4)NTCNQF(4) have been determined by X-ray crystallography. These TCNQF(4)(2-) salts will provide useful precursors for the synthesis of derivatives of the dianions. PMID:23153174

  7. Long-term measurements of atmospheric trace gases (CO2, CH4, N2O, SF6, CO, H2), O2, and δ13CH4 isotopes at Weybourne Atmospheric Observatory, UK: past, present and future

    NASA Astrophysics Data System (ADS)

    Manning, Andrew C.; Forster, Grant L.; Oram, David E.; Reeves, Claire E.; Pickers, Penelope A.; Barningham, S. Thomas; Sturges, William T.; Bandy, Brian; Nisbet, Euan G.; Lowry, David; Fisher, Rebecca; Fleming, Zoe

    2016-04-01

    The Weybourne Atmospheric Observatory (WAO) is situated on the north Norfolk Coast (52.95°N, 1.13°E) in the United Kingdom and is run by the University of East Anglia (UEA), with support from the UK National Centre for Atmospheric Science (NCAS). In 2016, the WAO became a UK-ICOS (Integrated Carbon Observing System) monitoring station. Since 2008, we have been collecting high-precision long-term in situ measurements of atmospheric carbon dioxide (CO2), oxygen (O2), carbon monoxide (CO) and molecular hydrogen (H2), as well as regular bag sampling for δ13CH4. In early 2013, the measurement of atmospheric methane (CH4) commenced, and nitrous oxide (N2O) and sulphur hexafluoride (SF6) began in 2014. We summarise the CO2, O2, CH4, N2O, SF6, CO, H2 and δ13CH4 measurements made to date and highlight some key features observed (e.g. seasonal cycles, long-term trends, pollution events and deposition events). We summarise how the long-term measurements fit into other broader projects which have helped to support the long term time-series at WAO over the years, and highlight how we contribute to broader global atmospheric observation networks.

  8. A sensitive impedimetric platform biosensing protein: Insoluble precipitates based on the biocatalysis of manganese(III) meso-tetrakis (4-N-methylpyridiniumyl)-porphyrinin in HCR-assisted dsDNA.

    PubMed

    Zhou, Xingxing; Xue, Shuyan; Jing, Pei; Xu, Wenju

    2016-12-15

    In this study, a sensitive biosensing interface for protein was reported based on nonconductive insoluble precipitates (IPs) by the biocatalysis of manganese(III) meso-tetrakis (4-N-methylpyridiniumyl)-porphyrin (MnTMPyP), which was intercalated into formed double-strand DNA (dsDNA) scaffold triggered by hybridization chain reaction (HCR). In the proposed impedimetric aptasensor, carcinoembryonic antigen (CEA) and its aptamer were used as testing model. PtPd nanowires (PtPdNWs) with large surface area and superior conductivity were employed as nanocarriers to greatly immobilize biomolecules (e.g. CEA aptamers). Then, two DNA hairpins H1 and H2 were introduced to trigger HCR with the assistance of DNA initiator, resulting in the formation of a long dsDNA scaffold. Meanwhile, mimicking enzyme MnTMPyP molecules were embedded into the resultant dsDNA, in situ generating the complex MnTMPyP-dsDNA with peroxidase-like activity. Under the biocatalysis of MnTMPyP-dsDNA, 3,3-diaminobenzidine (DAB) was oxidized to form nonconductive IPs. As a result, the electron transfer between electrode interface and redox probe was vastly hindered, leading to the significant amplification of electrochemical impedimetric signal. So, greatly improved analytical performances of the proposed aptasensor were achieved with a detection limit as low as 0.030pgmL(-1). And the successful assay of CEA in human serum samples enabled the developed biosensing platform to have promising potential in bioanalysis.

  9. Penetrating the Elusive Mechanism of Copper-Mediated Fluoromethylation in the Presence of Oxygen through the Gas-Phase Reactivity of Well-Defined [LCuO](+) Complexes with Fluoromethanes (CH(4-n)Fn, n = 1-3).

    PubMed

    Rijs, Nicole J; González-Navarrete, Patricio; Schlangen, Maria; Schwarz, Helmut

    2016-03-01

    Traveling wave ion mobility spectrometry (TWIMS) isomer separation was exploited to react the particularly well-defined ionic species [LCuO](+) (L = 1,10-phenanthroline) with the neutral fluoromethane substrates CH(4-n)Fn (n = 1-3) in the gas phase. Experimentally, the monofluoromethane substrate (n = 1) undergoes both hydrogen-atom transfer, forming the copper hydroxide complex [LCuOH](•+) and concomitantly a CH2F(•) radical, and oxygen-atom transfer, yielding the observable ionic product [LCu](+) plus the neutral oxidized substrate [C,H3,O,F]. DFT calculations reveal that the mechanism for both product channels relies on the initial C-H bond activation of the substrate. Compared to nonfluorinated methane, the addition of fluorine to the substrate assists the reactivity through a lowering of the C-H bond energy and reaction preorganization (through noncovalent interaction in the encounter complex). A two-state reactivity scenario is mandatory for the oxidation, which competitively results in the unusual fluoromethanol product, CH2FOH, or the decomposed products, CH2O and HF, with the latter channel being kinetically disfavored. Difluoromethane (n = 2) is predicted to undergo the analogous reactions at room temperature, although the reactions are less favored than those of monofluoromethane. The reaction of trifluoromethane (n = 3, fluoroform) through C-H activation is kinetically hindered under ambient conditions but might be expected to occur in the condensed phase upon heating or with further lowering of reaction barriers through templation with counterions, such as potassium. Overall, formation of CH(3-n)Fn(•) and CH(3-n)FnOH occurs under relatively gentle energetic conditions, which sheds light on their potential as reactive intermediates in fluoromethylation reactions mediated by copper in the presence of oxygen. PMID:26859159

  10. Diffusion of ion-implanted group 4 n-type dopants in gallium arsenide and gallium/arsenide-based superlattices

    NASA Astrophysics Data System (ADS)

    Allen, Emily Lin

    1992-09-01

    As semiconductor device dimensions shrink, understanding and controlling dopant diffusion becomes increasingly important. For submicron FET's made in GaAs, dopant diffusion during post-implant anneal is undesirable. In addition, impurity induced intermixing of III-V heterostructures for optoelectronic devices requires a series of carefully controlled diffusion steps. A more complete understanding of the diffusion mechanisms of dopants and point defects in both GaAs and Al(x)Ga(1-x)As is thus required for several advanced technologies. Most of the published parameters for diffusion of dopants in III-V compound semiconductors are from thin film or vapor source diffusions. The effect of implant damage and extended defects on diffusion of implanted dopants in GaAs and Al(x)Ga(1-x)As has not been extensively studied. In this work we measure the carrier concentrations and diffusivities of the ion-implanted Group IV dopants Sn, Ge and Si in GaAs and Al(x)Ga(1-x)As, using SIMS, polaron and SUPREM 3.5 simulations. In the substrate, diffusion is modeled by an effective diffusivity which depends on the square of the electron concentration (n), due to enhancement of the negatively charged Ga vacancy concentration by the n-type doping. In the near-surface implanted region diffusion is suppressed for doses greater than 1 x 10(exp 14)/sq cm. The carrier concentrations for Sn implants are anomalously high in this region, and anomalously low for Ge and Si. Transmission electron microscopy shows that precipitates and dislocations form in the implanted region during annealing for doses greater than 1 x 10(exp 14)/sq cm. These extended defects may influence dopant diffusion by controlling the generation and recombination of point defects. The carrier concentration-dependent diffusion model is applied to interdiffusion of Al and Ga in AlAs/Al(x)Ga(1-x)As superlattice structures. We show that interdiffusion is enhanced more under an oxide film than under a nitride film, while a tungsten

  11. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration

    PubMed Central

    Chang, Sung-Jin; Hyun, Moon Seop; Myung, Sung; Kang, Min-A; Yoo, Jung Ho; Lee, Kyoung G.; Choi, Bong Gill; Cho, Youngji; Lee, Gaehang; Park, Tae Jung

    2016-01-01

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties. PMID:26961409

  12. Chemical degradation of trimethyl phosphate as surrogate for organo-phosporus pesticides on nanostructured metal oxides

    SciTech Connect

    Štengl, Václav Henych, Jiří; Grygar, Tomáš; Pérez, Raúl

    2015-01-15

    Nanostructured TiO{sub 2} and mixed oxides of Ti and Fe, Hf, In, Mn or Zr -were prepared by homogeneous hydrolysis of aqueous solution of metal sulphates with urea. The oxides were characterised by X-ray powder diffraction (XRD), scanning electron microscopy, particle size distribution, surface area and porosity. The oxide materials consists of a few nanometre primary crystals (mainly anatase) arranged in a few micrometre regular spherical agglomerates with specific surface area 133–511 m{sup 2} g{sup −1}. The FTIR diffuse spectroscopy was used for monitoring chemical degradation of trimethylphosphate (TMP) as a surrogate for organo-phosphorus pesticides under ambient and higher temperatures. Undoped TiO{sub 2} and Ti,Mn-mixed oxide were most active in cleavage (hydrolysis) of CH{sub 3}O from TMP at room temperature and 100 °C. Cleavage of CH{sub 3}O in the other studied mixed oxides was not complete until temperature exceeds the boiling point of TMP.

  13. Epitaxial V{sub 0.6}W{sub 0.4}N/MgO(001): Evidence for ordering on the cation sublattice

    SciTech Connect

    Kindlund, H.; Lu, J.; Jensen, J.; Hultman, L.; Petrov, I.; Greene, J. E.

    2013-07-15

    V{sub 0.6}W{sub 0.4}N alloys are grown on MgO(001) by ultrahigh vacuum reactive magnetron sputtering from V and W targets in 10 mTorr pure-N{sub 2} atmospheres at temperatures T{sub s} ranging from 600 to 900 Degree-Sign C. Based on x-ray diffraction and transmission electron microscopy results, all films have the B1-NaCl crystal structure and grow with a cube-on-cube epitaxial relationship to the substrate, (001){sub VWN} Double-Vertical-Line (001){sub MgO} and [100]{sub VWN} Double-Vertical-Line [100]{sub MgO}. Rutherford backscattering spectrometry analyses show that the N content in V{sub 0.6}W{sub 0.4}N{sub x} alloys decreases with increasing T{sub s} from overstoichiometric with x = 1.13 at 600 Degree-Sign C, to approximately stoichiometric with x = 1.08 at 700 Degree-Sign C, to understoichiometric at 800 Degree-Sign C (x = 0.80) and 900 Degree-Sign C (x = 0.75). High-resolution scanning transmission electron microscopy, Z-contrast, and selected-area electron diffraction investigations of V{sub 0.6}W{sub 0.4}N(001) alloys grown at 600 and 700 Degree-Sign C reveal the onset of W ordering on adjacent 111 planes of the metal sublattice; no ordering is observed for understoichiometric films grown at higher temperatures.

  14. An Altered Immune Response, but Not Individual Cationic Antimicrobial Peptides, Is Associated with the Oral Attenuation of Ara4N-Deficient Salmonella enterica Serovar Typhimurium in Mice

    PubMed Central

    Tamayo, Rita; Reeves, Linh T.; Gunn, John S.

    2012-01-01

    Salmonella enterica serovar Typhimurium (S. Typhimurium) uses two-component regulatory systems (TCRS) to respond to stimuli in the local microenvironment. Upon infection, the Salmonella TCRSs PhoP-PhoQ (PhoPQ) and PmrA-PmrB (PmrAB) are activated by environmental signals in the intestinal lumen and within host cells. TCRS-mediated gene expression results in lipopolysaccharide (LPS) modification and cationic antimicrobial peptide resistance. The PmrA-regulated pmrHFIJKLM operon mediates 4-amino-4-deoxy-L-arabinose (Ara4N) production and attachment to the lipid A of LPS. A ΔpmrF S. Typhimurium strain cannot produce Ara4N, exhibits increased sensitivity to cationic antimicrobial peptide (CAMP)-mediated killing, and attenuated virulence in mice upon oral infection. CAMPs are predicted to play a role in elimination of Salmonella, and may activate PhoPQ and PmrAB in vivo, which could increase bacterial resistance to host defenses. Competition experiments between wild type (WT) and ΔpmrF mutant strains of S. Typhimurium indicated that selection against this mutant first occurs within the intestinal lumen early during infection. However, CRAMP and active cryptdins alone are not responsible for elimination of Ara4N-deficient bacteria in vivo. Investigation into the early immune response to ΔpmrF showed that it differed slightly from the early immune response to WT S. Typhimurium. Further investigation into the early immune response to infection of Peyer’s patches suggests a role for IL-13 in the attenution of the ΔpmrF mutant strain. Thus, prominent CAMPs present in the mouse intestine are not responsible for the selection against the ΔpmrF strain in this location, but limited alterations in innate immune induction were observed that affect bacterial survival and virulence. PMID:23166721

  15. Spectral detectability of CH4-N2 clathrates for in-situ and remote observation of Titan and other icy moons

    NASA Astrophysics Data System (ADS)

    Nna-Mvondo, D.; Tobie, G.; Le Menn, E.; Grasset, O.

    2015-10-01

    Multicomponent clathrates may be present at the surface of several icy moons, although they have not been detected yet, possibly due to the absence of reliable spectral data. In this work, w e present infrared (IR) and Raman spectral studies of CH4-N2 clathrates at low temperature and pressure, in order to identify discriminating criteria for their possible detection. These clathrates are particularly interesting for Titan and Pluto. Our experimental results indicate that identification of mixed clathrate from remote sensing is very challenging, and that only in- situ Raman spectroscopy may provide a clear identification of clathrate and co nstraints on their composition.

  16. Absorption intensities and complex refractive indices of crystalline HCN, HC3N, and C4N2 in the infrared region

    NASA Technical Reports Server (NTRS)

    Masterson, C. M.; Khanna, R. K.

    1990-01-01

    IR absorption intensities are presented for thin crystalline films of HCN, HC3N, and C4N2, together with n and k complex refractive indices determined on the basis of an iterative program for the Kramers-Konig integral via a least-squares, point-by-point fitting of the experimental transmission data. It is established that the transmission spectra generated by means of these n and k values can reproduce the experimental transmission observation values to within + or - 2 percent.

  17. Second hyperpolarizability of the calcium-doped lithium salt of pyridazine Li-H3C4N2 ⋯ Ca

    NASA Astrophysics Data System (ADS)

    Marques, Suélio; Castro, Marcos A.; Leão, Salviano A.; Fonseca, Tertius L.

    2016-08-01

    In this work we report results of coupled cluster calculations for the second hyperpolarizability of the calcium-doped lithium salt of pyridazine (Li-H3C4N2 ⋯ Ca) molecule. In the static limit an unusual value of 4.34 ×106 au was obtained at the CCSD level of calculation. Results obtained for the dc-Kerr effect through SCF, CCS and CCSD methods show that γ (- ω; ω, 0, 0) is strongly dependent of the electron correlation treatment. Dynamic results obtained at the CCSD level are also reported for the IDRI, dc-SHG and THG nonlinear optical processes.

  18. Synthesis, spectral characteristics, and the crystal and molecular structures of 2,3-dimethyl-1-phenyl-4-(N-phthalimido)pyrazolone-5

    SciTech Connect

    Sokol, V. I.; Strashnova, S. B. Kovalchukova, O. V.; Sergienko, V. S.; Davydov, V. V.; Zaitsev, B. E.; Evtushenko, Yu. M.

    2008-11-15

    2,3-Dimethyl-1-phenyl-4-(N-phthalimido)pyrazolone-5 (I) is synthesized and isolated in the form of single crystals. The crystal structure of compound I is determined using X-ray diffraction. The phthalimide and pyrazolone rings in the molecule are not coplanar: the angle between their median planes is 56.4{sup o}. The bond lengths in the rings level off, which indicates the delocalization of the electron density. The spectral characteristics (IR and electronic spectra) of molecule I are determined.

  19. meso-(4-(N,N-dialkylamino)phenyl)-substituted subporphyrins: remarkably perturbed absorption spectra and enhanced fluorescence by intramolecular charge transfer interactions.

    PubMed

    Inokuma, Yasuhide; Easwaramoorthi, Shanmugam; Yoon, Zin Seok; Kim, Dongho; Osuka, Atsuhiro

    2008-09-17

    A series of meso-(4-(N,N-dibenzylamino)phenyl)-substituted subporphyrins was synthesized by means of Buchwald-Hartwig amination protocol. Substitution of the amino group at the 4-position of the meso-phenyl substituent resulted in a remarkable red shift in the absorption spectra and drastic enhancement of fluorescence intensity probably as a consequence of intramolecular CT interaction. These characteristics have been utilized to construct a cation-sensing system by appending a 1-aza-15-crown-5 unit to subporphyrin that displays large spectral changes upon cation binding.

  20. Effects of substrates on N2O emissions in an anaerobic ammonium oxidation (anammox) reactor.

    PubMed

    Jin, Yue; Wang, Dunqiu; Zhang, Wenjie

    2016-01-01

    N2O emission in the anaerobic ammonium oxidation (anammox) process is of growing concern. In this study, effects of substrate concentrations on N2O emissions were investigated in an anammox reactor. Extremely high N2O emissions of 1.67 % were led by high NH4-N concentrations. Results showed that N2O emissions have a positive correlation with NH4-N concentrations in the anammox reactor. Reducing NH4-N concentrations by recycling pump resulted in decreasing N2O emissions. In addition, further studies were performed to identify a key biological process that is contributed to N2O emissions from the anammox reactor. Based on the results obtained, Nitrosomonas, which can oxidize ammonia to nitrite, was deemed as the main sources of N2O emissions. PMID:27376009

  1. Preservation of protein globules and peptidoglycan in the mineralized cell wall of nitrate-reducing, iron(II)-oxidizing bacteria: a cryo-electron microscopy study.

    PubMed

    Miot, J; Maclellan, K; Benzerara, K; Boisset, N

    2011-11-01

    Iron-oxidizing bacteria are important actors of the geochemical cycle of iron in modern environments and may have played a key role all over Earth's history. However, in order to better assess that role on the modern and the past Earth, there is a need for better understanding the mechanisms of bacterial iron oxidation and for defining potential biosignatures to be looked for in the geologic record. In this study, we investigated experimentally and at the nanometre scale the mineralization of iron-oxidizing bacteria with a combination of synchrotron-based scanning transmission X-ray microscopy (STXM), scanning transmission electron microscopy (STEM) and cryo-transmission electron microscopy (cryo-TEM). We show that the use of cryo-TEM instead of conventional microscopy provides detailed information of the successive iron biomineralization stages in anaerobic nitrate-reducing iron-oxidizing bacteria. These results suggest the existence of preferential Fe-binding and Fe-oxidizing sites on the outer face of the plasma membrane leading to the nucleation and growth of Fe minerals within the periplasm of these cells that eventually become completely encrusted. In contrast, the septa of dividing cells remain nonmineralized. In addition, the use of cryo-TEM offers a detailed view of the exceptional preservation of protein globules and the peptidoglycan within the Fe-mineralized cell walls of these bacteria. These organic molecules and ultrastructural details might be protected from further degradation by entrapment in the mineral matrix down to the nanometre scale. This is discussed in the light of previous studies on the properties of Fe-organic interactions and more generally on the fossilization of mineral-organic assemblies.

  2. Assessing the viability of extended nonmetal atom chains in M(n)F(4n+2) (M=S and Se).

    PubMed

    Popov, Ivan A; Averkiev, Boris B; Starikova, Alyona A; Boldyrev, Alexander I; Minyaev, Ruslan M; Minkin, Vladimir I

    2015-01-26

    Theoretical investigations to evaluate the viability of extended nonmetal atom chains on the basis of molecular models with the general formula Mn F4n+2 (M=S and Se) and corresponding solid-state systems exhibiting direct SS or SeSe bonding were performed. The proposed high-symmetry molecules were found to be minima on the potential energy surface for all Sn F4n+2 systems studied (n=2-9) and for selenium analogues up to n=6. Phonon calculations of periodic structures confirmed the dynamic stability of the -(SF4 -SF4 )∞ - chain, whereas the analogous -(SeF4 -SeF4 )∞ - chain was found to have a number of imaginary phonon frequencies. Chemical bonding analysis of the dynamically stable -(SF4 -SF4 )∞ - structure revealed a multicenter character of the SS and SF bonds. A novel definition and abbreviation (ENAC) are proposed by analogy with extended metal atom chain (EMAC) complexes.

  3. Removal of ZnO nanoparticles in simulated wastewater treatment processes and its effects on COD and NH(4)(+)-N reduction.

    PubMed

    Hou, Linlin; Xia, Jing; Li, Kaiyang; Chen, Jian; Wu, Xiaolei; Li, Xiqing

    2013-01-01

    For many engineered nanoparticles, the primary pathway of release into the environment is via sewage and industrial wastewater discharges. In this work, the removal of uncoated ZnO nanoparticles (ZnO NPs) during simulated wastewater treatment processes and its impact on treatment performance were examined. Simulated primary clarification removed the majority (about 70%) of the dosed ZnO NPs. During simulated sequencing batch reactor (SBR) processes, ZnO NPs were completely removed in each cycle throughout the 11-day experimental duration (two cycles per day). Continuous input of ZnO NPs into the wastewater (at concentrations up to 5 mg L(-1)) did not reduce chemical oxygen demand (COD) removal. NH(4)(+)-N removal was reduced at a dosing concentration of 5 mg L(-1) ZnO NPs per cycle. Inhibition of respiration of nitrifying microorganisms by ZnO NPs corroborated the reduction of NH(4)(+)-N removal. These results indicate that if the wastewater is treated, the release of ZnO NPs into receiving water bodies would be minimal and ZnO NPs would mainly accumulate in biosolids. Uncoated ZnO NPs in wastewater at very high concentrations may have some adverse effects on activated sludge process. PMID:23168621

  4. Magnetism by interfacial hybridization and p-type doping of MoS(2) in Fe(4)N/MoS(2) superlattices: a first-principles study.

    PubMed

    Feng, Nan; Mi, Wenbo; Cheng, Yingchun; Guo, Zaibing; Schwingenschlögl, Udo; Bai, Haili

    2014-03-26

    Magnetic and electronic properties of Fe4N(111)/MoS2(√3 × √3) superlattices are investigated by first-principles calculations, considering two models: (I) Fe(I)Fe(II)-S and (II) N-S interfaces, each with six stacking configurations. In model I, strong interfacial hybridization between Fe(I)/Fe(II) and S results in magnetism of monolayer MoS2, with a magnetic moment of 0.33 μB for Mo located on top of Fe(I). For model II, no magnetism is induced due to weak N-S interfacial bonding, and the semiconducting nature of monolayer MoS2 is preserved. Charge transfer between MoS2 and N results in p-type MoS2 with Schottky barrier heights of 0.5-0.6 eV. Our results demonstrate that the interfacial geometry and hybridization can be used to tune the magnetism and doping in Fe4N(111)/MoS2(√3 × √3) superlattices.

  5. Pressure-driven variations of hydrogen bonding energy in ammonium azide (NH4N3): IR absorption and Raman scattering studies.

    PubMed

    Wu, Xiaoxin; Ma, Fengxian; Ma, Chunli; Cui, Hang; Liu, Zhenxian; Zhu, Hongyang; Wang, Xiaoli; Cui, Qiliang

    2014-07-14

    In this study, high pressure infrared (IR) absorption and Raman scattering studies for ammonium azide (NH4N3) were carried out at room temperature up to 20 GPa and 22 GPa, respectively. For comparison and further assignment, the vibrational spectra at ambient conditions were calculated using CASTEP code, particularly for the far- and mid-IR modes. The recorded vibrational data consistently indicated a pressure-induced phase transition at 2.9 GPa. All observed vibrational modes maintained their identities at the high pressure phase, indicating that NH4N3 was still presented in the form of ammonium cations and azide anions linked by the hydrogen bond (N-H⋯N). Above 2.9 GPa, the relative magnitude of the torsional mode weakened and the N-H symmetric stretch displayed a redshift, indicating strengthened hydrogen bonding energy. The opposite effects were observed above 12 GPa, where the relative magnitude of the torsional mode strengthened and the N-H symmetric stretch reverted to a blueshift, indicating weakened hydrogen bonding energy. It can be concluded that the hydrogen bonding energy exhibited a weakening (0-2.9 GPa), strengthening (2.9-12 GPa), and then again weakening (12-22 GPa) phenomena with the increasing of compression. The hydrogen bonding energy changing with the increase of pressure can be ascribed to a phase transition at 2.9 GPa and a rotational or bending behavior of azide ions at 12 GPa.

  6. Influence of bulking agents on CH4, N2O, and NH3 emissions during rapid composting of pig manure from the Chinese Ganqinfen system*

    PubMed Central

    Sun, Xiang-ping; Lu, Peng; Jiang, Tao; Schuchardt, Frank; Li, Guo-xue

    2014-01-01

    Mismanagement of the composting process can result in emissions of CH4, N2O, and NH3, which have caused severe environmental problems. This study was aimed at determining whether CH4, N2O, and NH3 emissions from composting are affected by bulking agents during rapid composting of pig manure from the Chinese Ganqinfen system. Three bulking agents, corn stalks, spent mushroom compost, and sawdust, were used in composting with pig manure in 60 L reactors with forced aeration for more than a month. Gas emissions were measured continuously, and detailed gas emission patterns were obtained. Concentrations of NH3 and N2O from the composting pig manure mixed with corn stalks or sawdust were higher than those from the spent mushroom compost treatment, especially the sawdust treatment, which had the highest total nitrogen loss among the three runs. Most of the nitrogen was lost in the form of NH3, which accounts for 11.16% to 35.69% of the initial nitrogen. One-way analysis of variance for NH3 emission showed no significant differences between the corn stalk and sawdust treatments, but a significant difference was noted between the spent mushroom compost and sawdust treatments. The introduction of sawdust reduced CH4 emission more than the corn stalks and spent mushroom compost. However, there were no significant differences among the three runs for total carbon loss. All treatments were matured after 30 d. PMID:24711356

  7. Magnesium Oxide

    MedlinePlus

    ... different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. ... stomach.Do not take magnesium oxide as an antacid for longer than 2 weeks unless your doctor ...

  8. Radiation enhances the therapeutic effect of Banoxantrone in hypoxic tumour cells with elevated levels of nitric oxide synthase

    PubMed Central

    MEHIBEL, MANAL; SINGH, SIMENDRA; COWEN, RACHEL L.; WILLIAMS, KAYE J.; STRATFORD, IAN J.

    2016-01-01

    Banoxantrone (AQ4N) is a prototype hypoxia selective cytotoxin that is activated by haem containing reductases such as inducible nitric oxide synthase (iNOS). In the present study, we evaluate whether elevated levels of iNOS in human tumour cells will improve their sensitivity to AQ4N. Further, we examine the potential of radiation to increase cellular toxicity of AQ4N under normoxic (aerobic) and hypoxic conditions. We employed an expression vector containing the cDNA for human iNOS to transfect human fibrosarcoma HT1080 tumour cells. Alternatively, parental cells were exposed to a cytokine cocktail to induce iNOS gene expression and enzymatic activity. The cells were then treated with AQ4N alone and in combination with radiation in the presence or absence of the iNOS inhibitor N-methyl-L-arginine. In parental cells, AQ4N showed little difference in toxicity under hypoxic verses normoxic conditions. Notably, cells with upregulated iNOS activity showed a significant increase in sensitivity to AQ4N, but only under conditions of reduced oxygenation. When these cells were exposed to the combination of AQ4N and radiation, there was much greater cell killing than that observed with either modality alone. In the clinical development of hypoxia selective cytotoxins it is likely they will be used in combination with radiotherapy. In the present study, we demonstrated that AQ4N can selectively kill hypoxic cells via an iNOS-dependent mechanism. This hypoxia-selective effect can be augmented by combining AQ4N with radiation without increasing cytotoxicity to well-oxygenated tissues. Collectively, these results suggest that targeting hypoxic tumours with high levels of iNOS with a combination of AQ4N and radiotherapy could be a useful clinical therapeutic strategy. PMID:26782976

  9. Alkene oxidation catalyzed by a ruthenium-substituted heteropolyanion, SiRu(L)W sub 11 O sub 39 : The mechanism of the periodate mediated oxidative cleavage

    SciTech Connect

    Neumann, R.; Abu-Gnim, C. )

    1990-08-01

    A ruthenium-substituted heteropolyanion SiRu(H{sub 2}O)W{sub 11}O{sub 39}{sup 5{minus}} was synthesized and characterized. The hydrophobic quaternary ammonium salt of the heteropolyanion ((C{sub 6}H{sub 13}){sub 4}N){sub 5}SiRu{sup III}(H{sub 2}O)W{sub 11}O{sub 39} was used as a catalyst for the oxidation of alkenes with tert-butyl hydroperoxide, potassium persulfate, iodosobenzene, and sodium periodate as primary oxidants. Reactivity and selectivity were found to be dependent on the oxidant used; several different types of oxidation processes could be identified including allylic oxidation, epoxidation, and oxidative cleavage. Use of sodium periodate as oxidant enabled selective bond cleavage with aldehydes as the exclusive product.

  10. The Grapevine Root-Specific Aquaporin VvPIP2;4N Controls Root Hydraulic Conductance and Leaf Gas Exchange under Well-Watered Conditions But Not under Water Stress1[W

    PubMed Central

    Perrone, Irene; Gambino, Giorgio; Chitarra, Walter; Vitali, Marco; Pagliarani, Chiara; Riccomagno, Nadia; Balestrini, Raffaella; Kaldenhoff, Ralf; Uehlein, Norbert; Gribaudo, Ivana; Schubert, Andrea; Lovisolo, Claudio

    2012-01-01

    We functionally characterized the grape (Vitis vinifera) VvPIP2;4N (for Plasma membrane Intrinsic Protein) aquaporin gene. Expression of VvPIP2;4N in Xenopus laevis oocytes increased their swelling rate 54-fold. Northern blot and quantitative reverse transcription-polymerase chain reaction analyses showed that VvPIP2;4N is the most expressed PIP2 gene in root. In situ hybridization confirmed root localization in the cortical parenchyma and close to the endodermis. We then constitutively overexpressed VvPIP2;4N in grape ‘Brachetto’, and in the resulting transgenic plants we analyzed (1) the expression of endogenous and transgenic VvPIP2;4N and of four other aquaporins, (2) whole-plant, root, and leaf ecophysiological parameters, and (3) leaf abscisic acid content. Expression of transgenic VvPIP2;4N inhibited neither the expression of the endogenous gene nor that of other PIP aquaporins in both root and leaf. Under well-watered conditions, transgenic plants showed higher stomatal conductance, gas exchange, and shoot growth. The expression level of VvPIP2;4N (endogenous + transgene) was inversely correlated to root hydraulic resistance. The leaf component of total plant hydraulic resistance was low and unaffected by overexpression of VvPIP2;4N. Upon water stress, the overexpression of VvPIP2;4N induced a surge in leaf abscisic acid content and a decrease in stomatal conductance and leaf gas exchange. Our results show that aquaporin-mediated modifications of root hydraulics play a substantial role in the regulation of water flow in well-watered grapevine plants, while they have a minor role upon drought, probably because other signals, such as abscisic acid, take over the control of water flow. PMID:22923680

  11. Role of hydrogen on the deposition and properties of fluorinated silicon-nitride films prepared by inductively coupled plasma enhanced chemical vapor deposition using SiF{sub 4}/N{sub 2}/H{sub 2} mixtures

    SciTech Connect

    Fandino, J.; Santana, G.; Rodriguez-Fernandez, L.; Cheang-Wong, J.C.; Ortiz, A.; Alonso, J.C.

    2005-03-01

    Fluorinated silicon-nitride films have been prepared at low temperature (250 deg. C) by remote plasma enhanced chemical vapor deposition using mixtures of SiF{sub 4}, N{sub 2}, Ar, and various H{sub 2} flow rates. The deposited films were characterized by means of single wavelength ellipsometry, infrared transmission, resonant nuclear reactions, Rutherford backscattering analysis, and current-voltage measurements. It was found that films deposited without hydrogen grow with the highest deposition rate, however, they result with the highest fluorine content ({approx}27 at. %) and excess of silicon (Si/N ratio{approx_equal}1.75). These films also have the lowest refractive index and the highest etch rate, and exhibit very poor dielectric properties. As a consequence of the high fluorine content, these films hydrolize rapidly upon exposure to the ambient moisture, forming Si-H and N-H bonds, however, they do not oxidize completely. The addition of hydrogen to the deposition process reduces the deposition rate but improves systematically the stability and insulating properties of the films by reducing the amount of both silicon and fluorine incorporated during growth. All the fluorinated silicon-nitride films deposited at hydrogen flow rates higher than 3.5 sccm resulted free of Si-H bonds. In spite of the fact that films obtained at the highest hydrogen flow rate used in this work are still silicon rich (Si/N ratio{approx_equal}1.0) and contain a considerable amount of fluorine ({approx}16 at. %), they are chemically stable and show acceptable dielectric properties.

  12. Synthesis and structure of the extended phosphazane ligand [(1,4-C6H4){N(μ-PN(t)Bu)2N(t)Bu}2](4).

    PubMed

    Sevilla, Raquel; Less, Robert J; García-Rodríguez, Raúl; Bond, Andrew D; Wright, Dominic S

    2016-02-01

    The reaction of the phenylene-bridged precursor (1,4-C6H4)[N(PCl2)2]2 with (t)BuNH2 in the presence of Et3N gives the new ligand precursor (1,4-C6H4)[N(μ-N(t)Bu)2(PNH(t)Bu)2]2, deprotonation of which with Bu2Mg gives the novel tetraanion [(1,4-C6H4){N(μ-N(t)Bu)2(PN(t)Bu)2}2](4-).

  13. Trapping of Li(+) Ions by [ThFn](4-n) Clusters Leading to Oscillating Maxwell-Stefan Diffusivity in the Molten Salt LiF-ThF4.

    PubMed

    Chakraborty, Brahmananda; Kidwai, Sharif; Ramaniah, Lavanya M

    2016-08-18

    A molten salt mixture of lithium fluoride and thorium fluoride (LiF-ThF4) serves as a fuel as well as a coolant in the most sophisticated molten salt reactor (MSR). Here, we report for the first time dynamic correlations, Onsager coefficients, Maxwell-Stefan (MS) diffusivities, and the concentration dependence of density and enthalpy of the molten salt mixture LiF-ThF4 at 1200 K in the composition range of 2-45% ThF4 and also at eutectic composition in the temperature range of 1123-1600 K using Green-Kubo formalism and equilibrium molecular dynamics simulations. We have observed an interesting oscillating pattern for the MS diffusivity for the cation-cation pair, in which ĐLi-Th oscillates between positive and negative values with the amplitude of the oscillation reducing as the system becomes rich in ThF4. Through the velocity autocorrelation function, vibrational density of states, radial distribution function analysis, and structural snapshots, we establish an interplay between the local structure and multicomponent dynamics and predict that formation of negatively charged [ThFn](4-n) clusters at a higher ThF4 mole % makes positively charged Li(+) ions oscillate between different clusters, with their range of motion reducing as the number of [ThFn](4-n) clusters increases, and finally Li(+) ions almost get trapped at a higher ThF4% when the electrostatic force on Li(+) exerted by various surrounding clusters gets balanced. Although reports on variations of density and enthalpy with temperature exist in the literature, for the first time we report variations of the density and enthalpy of LiF-ThF4 with the concentration of ThF4 (mole %) and fit them with the square root function of ThF4 concentration, which will be very useful for experimentalists to obtain data over a range of concentrations from fitting the formula for design purposes. The formation of [ThFn](4-n) clusters and the reduction in the diffusivity of the ions at a higher ThF4% may limit the

  14. Trapping of Li(+) Ions by [ThFn](4-n) Clusters Leading to Oscillating Maxwell-Stefan Diffusivity in the Molten Salt LiF-ThF4.

    PubMed

    Chakraborty, Brahmananda; Kidwai, Sharif; Ramaniah, Lavanya M

    2016-08-18

    A molten salt mixture of lithium fluoride and thorium fluoride (LiF-ThF4) serves as a fuel as well as a coolant in the most sophisticated molten salt reactor (MSR). Here, we report for the first time dynamic correlations, Onsager coefficients, Maxwell-Stefan (MS) diffusivities, and the concentration dependence of density and enthalpy of the molten salt mixture LiF-ThF4 at 1200 K in the composition range of 2-45% ThF4 and also at eutectic composition in the temperature range of 1123-1600 K using Green-Kubo formalism and equilibrium molecular dynamics simulations. We have observed an interesting oscillating pattern for the MS diffusivity for the cation-cation pair, in which ĐLi-Th oscillates between positive and negative values with the amplitude of the oscillation reducing as the system becomes rich in ThF4. Through the velocity autocorrelation function, vibrational density of states, radial distribution function analysis, and structural snapshots, we establish an interplay between the local structure and multicomponent dynamics and predict that formation of negatively charged [ThFn](4-n) clusters at a higher ThF4 mole % makes positively charged Li(+) ions oscillate between different clusters, with their range of motion reducing as the number of [ThFn](4-n) clusters increases, and finally Li(+) ions almost get trapped at a higher ThF4% when the electrostatic force on Li(+) exerted by various surrounding clusters gets balanced. Although reports on variations of density and enthalpy with temperature exist in the literature, for the first time we report variations of the density and enthalpy of LiF-ThF4 with the concentration of ThF4 (mole %) and fit them with the square root function of ThF4 concentration, which will be very useful for experimentalists to obtain data over a range of concentrations from fitting the formula for design purposes. The formation of [ThFn](4-n) clusters and the reduction in the diffusivity of the ions at a higher ThF4% may limit the

  15. Theoretical study for the excited states of MoO4 - nS2 - n (n=0 ~ 4) and MoSe2 - 4

    NASA Astrophysics Data System (ADS)

    Nakatsuji, Hiroshi; Saito, Shinji

    1990-08-01

    Ground and excited states of six molybdenum complexes, MoO4-nS2-n (n=0˜4) and MoSe2-4, are systematically studied by symmetry adapted cluster (SAC) and SAC-CI theories. In the ground states, the ionicity of MoO2-4 is much larger than those of MoS2-4 and MoSe2-4. The calculated electronic spectra compare well with the observed spectra. New systematic assignments of the spectra are given. Most of the peaks are assigned to the electron-transfer type transitions from ligands to the metal. Many assignments are different from the previous ones. The observed relationships in the electronic spectra of these complexes are examined and corrected. The solvation effect is argued briefly.

  16. Endo-N-acetyl-beta-D-glucosaminidase and peptide-N4-(N-acetyl-glucosaminyl) asparagine amidase activities during germination of Raphanus sativus.

    PubMed

    Berger, S; Menudier, A; Julien, R; Karamanos, Y

    1995-06-01

    Endo-N-acetyl-beta-D-glucosaminidase (ENGase, EC 3.2.1.96) and peptide-N4-(N-acetyl-beta-D-glucosaminyl) asparagine amidase (PNGase, EC 3.5.1.52) activities were monitored during germination and postgerminative development in Raphanus sativus. The PNGase activity was found in dry seeds and its level was constant during germination and postgermination. The ENGase activity was first detected about 18 hr after the start of imbibition (HAI) and displayed a maximum level at 36 HAI. After 36 HAI the production of both enzymes was constant until days 4-5. Both enzymes displayed substrate specificities corresponding to the potential glycoprotein substrates found in plants. They are in agreement (i) with the hypothesis that ENGase and PNGase are at the origin of the production of 'unconjugated N-glycans' and (ii) with the possibility that protein activity could be regulated by the removal of N-glycans.

  17. Dependency of temperature on polarization in CH{sub 4}/N{sub 2} dielectric barrier discharge plasma: A crude assumption

    SciTech Connect

    Majumdar, Abhijit; Hippler, Rainer; Ghosh, Basudev

    2010-11-15

    We have investigated the variations of polarization (P) and the temperature ({Delta}T) at the electrode surfaces during the deposition of C-N layer in CH{sub 4}/N{sub 2} (1:2) dielectric barrier discharge plasma. The reactive deposition process influences the surface temperature, polarization, and the value of the in situ dielectric constant. We have developed a crude model that correlates the surface temperature and surface polarization with thin film properties. We assume that during the thin film deposition process, the atomic mean kinetic energy is equal to the electrostatic energy stored in the electrode surface area. Theoretically estimated temperature is found to agree well with the experimental results. However, the linear model thus developed cannot be used to explain the phenomena in the interfacial polarization stage that requires a nonlinear theory.

  18. Using Raman spectroscopy to understand the origin of the phase transitions observed in [(C3H7)4N]2Zn2Cl6 compound

    NASA Astrophysics Data System (ADS)

    Ben Gzaiel, M.; Oueslati, A.; Chaabane, I.; Bulou, A.; Hlel, F.; Gargouri, M.

    2015-06-01

    Phase transitions of the centrosymmetric compound, [(C3H7)4N]2Zn2Cl6, were studied by differential scanning calorimetry (DSC), X-ray diffraction, Raman spectroscopy and dielectric measurements. Two reversible order-disorder and displacive phase transitions are observed at T1 = 327 K and T2 = 347 K with 3 K and 4 K hysteresis respectively, indicating a first order character. The evolution of Raman line shifts, "ν", and the half-width, "Δν", versus temperature show some singularities associated with the transitions, suggesting that they are governed by the reorientational and the displacement of the organic part. Besides the results of the dielectric permittivity study confirms the conclusion drawn from the calorimetric and Raman measurements that the phase transition located in the vicinity of the temperature of the dielectric proprieties is characterized by change of dynamical state of cation.

  19. EFFICIENT CONTROL OVER THE PORE STRUCTURE OF Fe3O4-nSiO2-mSiO2 CORE-SHELL NANOPARTICLES

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Tian, Hua; He, Junhui; Liu, Hongying

    2012-01-01

    In this paper, magnetic mesoporous silica nanoparticles (Fe3O4-nSiO2-mSiO2) were synthesized using trimethylbenzene (TMB) as a swelling agent. These composite nanoparticles have a typical sandwich structure with a magnetic core, a nonporous silica middle layer and an ordered mesoporous silica outer shell. The experimental results indicate that the magnetic mesoporous silica nanoparticles have high specific surface area (510 m2/g), large pore size (3.8 nm) and pore volume (1.04 cm3/g). The thickness and pore structure of the out shell can also be easily tailored by adjusting the reaction conditions. The obtained nanomaterials were characterized by X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption measurements.

  20. New yellow-emitting nitride phosphor SrAlSi4N7:Ce3+ and important role of excessive AlN in material synthesis.

    PubMed

    Zhang, Liangliang; Zhang, Jiahua; Zhang, Xia; Hao, Zhendong; Zhao, Haifeng; Luo, Yongshi

    2013-12-26

    Synthesis and luminescent properties of Ce(3+)-doped SrAlSi4N7 yellow-emitting phosphor are reported. In comparison with YAG: Ce(3+), the phosphor exhibits smaller thermal quenching and a broader emission band centering at 555 nm with a bandwidth as large as 115 nm, being suitable for fabricating high color rendering white LED. It is observed in material synthesis that intense luminescence can be achieved only in case of excessive AlN in the raw materials. The role of the excessive AlN is studied. The mechanism for existence of edge-sharing [AlN4] tetrahedral, which is unreasonable according to the aluminum avoidance principle, is discussed in detail.

  1. Quasi-one-dimensional quantum spin liquid in the Cu(C4H4N2)(NO3)2 insulator

    NASA Astrophysics Data System (ADS)

    Shaginyan, V. R.; Stephanovich, V. A.; Popov, K. G.; Kirichenko, E. V.

    2016-01-01

    We analyze measurements of the magnetization, differential susceptibility and specific heat of quasi-onedimensional insulator Cu(C4H4N2)(NO3)2 (CuPzN) subjected to magnetic fields. We show that the thermodynamic properties are defined by quantum spin liquid formed with spinons, with the magnetic field tuning the insulator CuPzN towards quantum critical point related to fermion condensation quantum phase transition (FCQPT) at which the spinon effective mass diverges kinematically. We show that the FCQPT concept permits to reveal and explain the scaling behavior of thermodynamic characteristics. For the first time, we construct the schematic T-H (temperature-magnetic field) phase diagram of CuPzN that contains Landau-Fermi-liquid, crossover and non-Fermi liquid parts, thus resembling that of heavy-fermion compounds.

  2. Sectoral CO 2, CH 4, N 2O and SO 2 emissions from fossil fuel consumption in Nagpur City of Central India

    NASA Astrophysics Data System (ADS)

    Majumdar, Deepanjan; Gajghate, D. G.

    2011-08-01

    Emission inventory of CO 2, CH 4, N 2O and SO 2 has been prepared for Nagpur city in Central India for the year 2004. Data on fossil fuel (coal, light diesel oil, high speed diesel, petrol/gasoline, low sulphur heavy stock, furnace oil and kerosene) consumption in thermal power, industrial, transport and domestic sectors were collected. Thermal power sector had the maximum coal consumption followed by the industrial and domestic sectors, whereas kerosene, liquefied petroleum gas (LPG), diesel and gasoline were used only in any single sector. Total annual CO 2, CH 4, N 2O and SO 2 emissions from these fuels in Nagpur city for the year 2004 was found to be 14792418 MT (14.8 Tg), 4649 (4.6 Tg), 1529 (1.5 Tg) and 69093 (6.9 Tg), respectively, in which thermal power and domestic sector had the maximum share. Coal was found to be the major contributor to Green House Gas (GHG) and SO 2 emissions in all the sectors barring transport and domestic sectors. Carbon dioxide was the predominant GHG emitted by the selected sectors in terms of absolute emissions and also global warming contribution (GWC), though the share in the latter was lesser in magnitude due to higher global warming potential (GWP) of CH 4 and N 2O than CO 2. Thermal power sector had a share of 51% in total CO 2 emissions from all the sectors, followed by domestic, industrial and transport sectors having 27, 12 and 10% contributions, respectively. Share of thermal power sector in total SO 2 emissions was 61%, followed by 24% from industrial, 10% from domestic and 5% from transport sector.

  3. Analysis of the Vibrational Spectra of P_3N_3(OCH_2CF_3)_6 and P_4N_4(OCH_2CF_3)_8

    NASA Astrophysics Data System (ADS)

    King, Adrian K.; Plant, David F.; Golding, Peter; Lawson, Michael A.; Davies, Paul B.

    2011-06-01

    The cyclic phosphazene trimer P_3N_3(OCH_2CF_3)_6 and the related cyclic tetramer P_4N_4(OCH_2CF_3)_8 have been proposed as the major low-to-medium temperature pyrolysis products of the parent polyphosphazene (PN(OCH_2CF_3)_2)_n. Recently, both molecules have been synthesized, isolated and their vapour-phase vibrational spectra recorded using a high-resolution FTIR instrument. The interpretation of these spectra is achieved primarily by comparison with the results of high-quality density functional calculations, which enable the principal absorption features to be assigned and conclusions to be drawn regarding the geometries and conformations adopted by both molecules. These in turn allow interesting comparisons to be made with analogous cyclic halo-phosphazenes such as P_3N_3Cl_6 and P_4N_4Cl_8. Work to record in situ the spectra of the vapour-phase pyrolysis products of (PN(OCH_2CF_3)_2)_n and to analyse these results in terms of the tetramer and trimer spectra will also be presented. S. V. Peddada and J. H. Magill Macromolecules 16 (1983) 1258-1264. H. R. Allcock, G. S. McDonnell, G. H. Riding, and I. Manners Chem. Mater. 2 (1990) 425-432. T. R. Manley and D. A. Williams Spectrochimica Acta 23A (1966) 149-165. V. Varma, J. R. Fernandez and C. N. R. Rao J. Mol. Struct. 198 (1989) 403-412.

  4. Structural, spectral, electrochemistry, thermal properties and theoretical studies on 4-[N, N-di(4-tolyl)amino] benzaldehyde-2-chloro benzoylhydrazone

    NASA Astrophysics Data System (ADS)

    Lizeng, Liu; Wei, Li; Xianfang, Meng; Dongzhi, Liu; Gongfeng, Xu; Zhengchen, Bai

    2014-11-01

    The title compound 4-[N, N-di(4-tolyl)amino] benzaldehyde-2-chloro benzoylhydrazone (C28H24ClN3O, Mr = 453.96) was synthesized by the reaction of 4-[N, N-di(4-tolyl)amino] benzaldehyde with 2-chlorobenzohydrazide, and its structure was characterized by IR, 1H NMR, 13H NMR, high-resolution mass spectrometry and single-crystal X-ray diffraction. The crystal belongs to Monoclinic, space group P2(1)/n with a = 12.626(3), b = 12.609(3), c = 15.837(3) Å, β = 90.00(3)°, Z = 5, V = 2512.5(9) Å3, Mr = 453.95, Dc = 1.280 g/cm3, μ = 0.183 mm-1, F(0 0 0) = 1024, R = 0.0432 and wR = 0.1087. X-ray analysis revealed that one of the benzene ring and acylhydrazone were essentially planar, the 2-chloro benzene ring and amide were non-planar, the torsion angles C(1)sbnd C(6)sbnd C(7)sbnd O(1) and C(5)sbnd C(6)sbnd C(7)sbnd O(1) are 61.4(5)° and -114.4(4)°. The thermal stability studies indicate that the title compound is stable up to 341.1 °C. The spectral, electrochemistry properties and theoretical studies show that the title compound is a good candidate for the charge-transporting materials.

  5. Influence of terminal substitution on structural, DNA, protein binding, anticancer and antibacterial activities of palladium(II) complexes containing 3-methoxy salicylaldehyde-4(N) substituted thiosemicarbazones.

    PubMed

    Kalaivani, P; Prabhakaran, R; Ramachandran, E; Dallemer, F; Paramaguru, G; Renganathan, R; Poornima, P; Vijaya Padma, V; Natarajan, K

    2012-02-28

    The variable chelating behavior of 3-methoxysalicylaldehyde-4(N)-substituted thiosemicarbazones was observed in equimolar reactions with [PdCl(2)(PPh(3))(2)]. The new complexes were characterized by various analytical, spectroscopic techniques (mass, (1)H-NMR, absorption, IR). All the new complexes were structurally characterized by single crystal X-ray diffraction. Crystallographic results showed that the ligands H(2)L(1) and H(2)L(4) are coordinated as binegative tridentate ONS donor ligands in the complexes 1 and 4 by forming six and five member rings. However, the ligands H(2)L(2) and H(2)L(3) bound to palladium in 2 and 3 as uninegative bidentate NS donors by forming a five member chelate ring. From this study, it was found that the substitution on terminal 4(N)-nitrogen may have an influence on the chelating ability of thiosemicarbazone. The presence of hydrogen bonding in 2 and 3 might be responsible for preventing the coordination of phenolic oxygen to the metal ion. The interaction of the complexes with calf-thymus DNA (CT-DNA) has been explored by absorption and emission titration methods. Based on the observations, an electrostatic binding mode of DNA has been proposed. The protein binding studies were monitored by quenching of tryptophan and tyrosine residues in the presence of complexes using Lysozyme as model protein. Antibacterial activity studies of the complexes have been screened against pathogenic bacteria such as Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa. MIC50 values of the complexes showed that they exhibited significant activity against the pathogens and among them, 3 exhibited higher activity. Further, anticancer activity of the complexes on the lung cancer cell line A549 has also been studied. PMID:22222360

  6. [Characteristics of sulfate reduction-ammonia oxidation reaction].

    PubMed

    Yuan, Yi; Huang, Yong; Li, Xiang; Zhang, Chun-Lei; Zhang, Li; Pan, Yang; Liu, Fu-Xin

    2013-11-01

    The sulfate reduction-ammonia oxidation reaction with ANAMMOX sludge at autotrophic condition was implemented. It was found that the pH level decreased during the reaction. Elemental sulfur and nitrogen gas were the final products, while NO3(-) -N was the intermediate product during the sulfate reduction-ammonia oxidation reaction. The conversion ratio of NH4(+) -N/SO4(2-) -S decreased with the decrease in n(N)/n(S) (molar ratio) of raw water. n(N)/n(S) of raw water had little effect on the ammonia conversion ratio. Lower n(N)/n(S) could improve the SO4(2-)-S conversion ratio, but with more NH4(+) -N oxidized into NO3(-) -N, resulting in decreased n(TN)/n(TS) removal ratio. This indicates that the sulfate reduction-ammonia oxidation reaction is not an elementary reaction. Ammonia can be oxidized into NO2(-) -N or NO3(-) -N by sulfate. Shortening the reaction time would be conducive to nitrogen losses, because the reaction of NO3(-) -N production is the rate-limiting step.

  7. Oxide Thermoelectrics

    SciTech Connect

    Singh, David J

    2008-01-01

    Thermoelectricity in oxides, especially NaxCoO2 and related materials, is discussed from the point of view of first principles calculations and Boltzmann transport theory. The electronic structure of this material is exceptional in that it has a combination of very narrow bands and strong hybridization between metal d states and ligand p states. As shown within the framework of conventional Boltzmann transport theory, this leads to high Seebeck coefficients even at metallic carrier densities. This suggests a strategy of searching for other narrow band oxides that can be doped metallic with mobile carriers. Some possible avenues for finding such materials are suggested.

  8. Oxidation catalyst

    DOEpatents

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  9. An innovative architectural design to enhance the electrochemical performance of La2NiO4+δ cathodes for solid oxide fuel cell applications

    NASA Astrophysics Data System (ADS)

    Sharma, Rakesh K.; Burriel, Mónica; Dessemond, Laurent; Martin, Vincent; Bassat, Jean-Marc; Djurado, Elisabeth

    2016-06-01

    An architectural design of the cathode microstructure based on combining electrostatic spray deposition (ESD) and screen-printing (SP) techniques has demonstrated to be an innovative strategy to enhance the electrochemical properties of La2NiO4+δ (LNO) as oxygen electrode on Ce0.9Gd0.1O2-δ (CGO) electrolyte for solid oxide fuel cells. For this purpose, the influence of the ESD process parameters on the microstructure has been systematically investigated. Electrochemical performances of four selected cathode microstructures are investigated: (i) 3-D coral nanocrystalline (average particle size ∼ 100 nm) LNO film grown by ESD; (ii) 3-D coral nanocrystalline film (average particle size ∼ 150 nm) grown by ESD with a continuous nanometric dense interface; (iii) porous screen-printed LNO film (average particle size ∼ 400 nm); and (iv) 3-D coral nanocrystalline film (average particle size ∼ 150 nm) with a continuous nanometric dense interface prepared by ESD topped by a LNO current collector prepared by SP. A significant reduction in the polarization resistance (Rpol) is obtained (0.08 Ω cm2 at 700 °C) for 3-D coral topped by the SP layer. Moreover LNO is found to be stable and compatible with CGO up to 800 °C for only 10 days duration in air, making it potentially suitable for SOFCs cathode application.

  10. EBSD characterisation of Y2Ba4CuUOx phase in melttextured YBCO with addition of depleted uranium oxide

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Mücklich, F.; Koblischka, M. R.; Babu, N. Hari; Cardwell, D. A.

    2006-06-01

    Melt-textured YBCO samples processed with added Y2O3 and depleted uranium oxide (DU) contain nano-particles, which have been identified previously as Y2Ba4CuUOx (U-411). This phase has a cubic unit cell, which is clearly distinct from the orthorhombic Y-123 and Y-211 phases within the YBCO system. In samples with a high amount of DU addition (0.8 wt-% DU), U-2411 particles have sizes between 200 nm and several µm, so identification of the Kikuchi patterns of this phase becomes possible. Together with a parallel EDX analysis, the particles embedded in the Y-123 matrix can be identified unambiguously. In this way, a three-phase EBSD scan becomes possible, allowing also the identification of nanometre-sized particles in the sample microstructure.

  11. Direct Observation, Molecular Structure, and Location of Oxidation Debris on Graphene Oxide Nanosheets.

    PubMed

    Chen, Xiaoxiao; Chen, Baoliang

    2016-08-16

    The presence of oxidation debris (OD) complicates the structures and properties of graphene oxide (GO) nanosheets, thereby impacting their potential applications. However, the origin of OD is still in dispute. Moreover, characterizing the structure and location of supposed OD on nanosheets of GO produced during the oxidation process is difficult. Herein, the attached state and size of OD on graphene oxide nanosheets were directly observed using HRTEM, the molecular structure of OD was initially proposed based on the spectroscopic characterization and Q-TOF mass spectrometry, and the locations of OD on the GO nanosheets were detected through the adsorption of probe molecules onto as-prepared GO (a-GO) and base-washed GO (bw-GO). The results indicated that OD possesses a highly crystalline structure and can be defined as several nanometre-sized polyaromatic molecules with a considerable number of oxygen-containing functional groups attached on the edges. The dark nanodot seated on a-GO was clearly observed in the HRTEM images, whereas it appeared as a clean nanosheet in the image of bw-GO, indicating that OD is removed by base-washing treatment. Following the base-washing treatment, the contents of carboxyl groups on bw-GO unexpectedly increased and subsequently contributed to the desorption of OD from a-GO due to the electrostatic repulsion being stronger than primary π-π interactions. Compared with a-GO, the adsorption of phenanthrene, as an aromatic probe, onto bw-GO increased by 6-fold via π-π stacking interactions, whereas the increase in the adsorption of m-dinitrobenzene, as a defect probe, was not as remarkable as that of phenanthrene. Reasonably, the OD nanoparticles were primarily located at the sp(2) structures on the GO nanosheets through π-π interactions rather than attached on defects/edges. The insights regarding the existence, molecular structures and attached sites of OD nanoparticles on GO nanosheets provide a theoretical basis for preparing

  12. Thallium oxide

    Integrated Risk Information System (IRIS)

    Thallium oxide ; CASRN 1314 - 32 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic E

  13. Propylene oxide

    Integrated Risk Information System (IRIS)

    Propylene oxide ; CASRN 75 - 56 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  14. Nitric oxide

    Integrated Risk Information System (IRIS)

    Nitric oxide ; CASRN 10102 - 43 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  15. Merphos oxide

    Integrated Risk Information System (IRIS)

    Merphos oxide ; CASRN 78 - 48 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effe

  16. Nanometrization of Lanthanide-Based Coordination Polymers.

    PubMed

    Neaime, Chrystelle; Daiguebonne, Carole; Calvez, Guillaume; Freslon, Stéphane; Bernot, Kevin; Grasset, Fabien; Cordier, Stéphane; Guillou, Olivier

    2015-11-23

    Heteronuclear lanthanide-based coordination polymers are microcrystalline powders, the luminescence properties of which can be precisely tuned by judicious choice of the rare-earth ions. In this study, we demonstrate that such materials can also be obtained as stable solutions of nanoparticles in non-toxic polyols. Bulk powders of the formula [Ln2-2x Ln'2x (bdc)3 ⋅4 H2 O]∞ (where H2 bdc denotes 1,4-benzene-dicarboxylic acid, 0≤x≤1, and Ln and Ln' denote lanthanide ions of the series La to Tm plus Y) afford nanoparticles that have been characterized by dynamic light-scattering (DLS) and transmission electron microscopy (TEM) measurements. Their luminescence properties are similar to those of the bulk materials. Stabilities versus time and versus dilution with another solvent have been studied. This study has revealed that it is possible to tune the size of the nanoparticles. This process offers a reliable means of synthesizing suspensions of nanoparticles with tunable luminescence properties and tunable size distributions in a green solvent (glycerol). The process is also extendable to other coordination polymers and other solvents (ethylene glycol, for example). It constitutes a new route for the facile solubilization of lanthanide-based coordination polymers. PMID:26471940

  17. Nanometrization of Lanthanide-Based Coordination Polymers.

    PubMed

    Neaime, Chrystelle; Daiguebonne, Carole; Calvez, Guillaume; Freslon, Stéphane; Bernot, Kevin; Grasset, Fabien; Cordier, Stéphane; Guillou, Olivier

    2015-11-23

    Heteronuclear lanthanide-based coordination polymers are microcrystalline powders, the luminescence properties of which can be precisely tuned by judicious choice of the rare-earth ions. In this study, we demonstrate that such materials can also be obtained as stable solutions of nanoparticles in non-toxic polyols. Bulk powders of the formula [Ln2-2x Ln'2x (bdc)3 ⋅4 H2 O]∞ (where H2 bdc denotes 1,4-benzene-dicarboxylic acid, 0≤x≤1, and Ln and Ln' denote lanthanide ions of the series La to Tm plus Y) afford nanoparticles that have been characterized by dynamic light-scattering (DLS) and transmission electron microscopy (TEM) measurements. Their luminescence properties are similar to those of the bulk materials. Stabilities versus time and versus dilution with another solvent have been studied. This study has revealed that it is possible to tune the size of the nanoparticles. This process offers a reliable means of synthesizing suspensions of nanoparticles with tunable luminescence properties and tunable size distributions in a green solvent (glycerol). The process is also extendable to other coordination polymers and other solvents (ethylene glycol, for example). It constitutes a new route for the facile solubilization of lanthanide-based coordination polymers.

  18. Modern steels at atomic and nanometre scales

    SciTech Connect

    Caballero, F. G.; Garcia-Mateo, C.; Miller, M. K.

    2014-10-10

    Processing bulk nanocrystalline materials for structural applications still poses a difficult challenge, particularly in achieving an industrially viable process. Recent work in ferritic steels has proved that it is possible to move from ultrafine to nanoscale by exploiting the bainite reaction without the use of severe deformation, rapid heat treatment or mechanical processing. This new generation of steels has been designed in which transformation at low temperature leads to a nanoscale structure consisting of extremely fine, 20–40 nm thick plates of bainitic ferrite and films of retained austenite. Finally, a description of the characteristics and significance of this remarkable microstructure is provided here.

  19. Modern steels at atomic and nanometre scales

    DOE PAGES

    Caballero, F. G.; Garcia-Mateo, C.; Miller, M. K.

    2014-10-10

    Processing bulk nanocrystalline materials for structural applications still poses a difficult challenge, particularly in achieving an industrially viable process. Recent work in ferritic steels has proved that it is possible to move from ultrafine to nanoscale by exploiting the bainite reaction without the use of severe deformation, rapid heat treatment or mechanical processing. This new generation of steels has been designed in which transformation at low temperature leads to a nanoscale structure consisting of extremely fine, 20–40 nm thick plates of bainitic ferrite and films of retained austenite. Finally, a description of the characteristics and significance of this remarkable microstructuremore » is provided here.« less

  20. Heat of combustion of tantalum-tungsten oxide thermite composites

    SciTech Connect

    Cervantes, Octavio G.; Kuntz, Joshua D.; Gash, Alexander E.; Munir, Zuhair A.

    2010-12-15

    The heat of combustion of two distinctly synthesized stoichiometric tantalum-tungsten oxide energetic composites was investigated by bomb calorimetry. One composite was synthesized using a sol-gel (SG) derived method in which micrometric-scale tantalum is immobilized in a tungsten oxide three-dimensional nanostructured network structure. The second energetic composite was made from the mixing of micrometric-scale tantalum and commercially available (CA) nanometric tungsten oxide powders. The energetic composites were consolidated using the spark plasma sintering (SPS) technique under a 300 MPa pressure and at temperatures of 25, 400, and 500 C. For samples consolidated at 25 C, the density of the CA composite is 61.65 {+-} 1.07% in comparison to 56.41 {+-} 1.19% for the SG derived composite. In contrast, the resulting densities of the SG composite are higher than the CA composite for samples consolidated at 400 and 500 C. The theoretical maximum density for the SG composite consolidated to 400 and 500 C are 81.30 {+-} 0.58% and 84.42 {+-} 0.62%, respectively. The theoretical maximum density of the CA composite consolidated to 400 and 500 C are 74.54 {+-} 0.80% and 77.90 {+-} 0.79%, respectively. X-ray diffraction analyses showed an increase of pre-reaction of the constituents with an increase in the consolidation temperature. The increase in pre-reaction results in lower stored energy content for samples consolidated to 400 and 500 C in comparison to samples consolidated at 25 C. (author)

  1. Design of a highly sensitive ethanol sensor using a nano-coaxial p-Co3O4/n-TiO2 heterojunction synthesized at low temperature

    NASA Astrophysics Data System (ADS)

    Liang, Y. Q.; Cui, Z. D.; Zhu, S. L.; Li, Z. Y.; Yang, X. J.; Chen, Y. J.; Ma, J. M.

    2013-10-01

    In this paper, we describe the design, fabrication and gas-sensing tests of nano-coaxial p-Co3O4/n-TiO2 heterojunction. Specifically, uniform TiO2 nanotubular arrays have been assembled by anodization and used as templates for generation of the Co3O4 one-dimensional nanorods. The structure morphology and composition of as-prepared products have been characterized by SEM, XRD, TEM, and XPS. A possible growth mechanism governing the formation of such nano-coaxial heterojunctions is proposed. The TiO2 nanotube sensor shows a normal n-type response to reducing ethanol gas, whereas TiO2-Co3O4 exhibits p-type response with excellent sensing performances. This conversion of sensing behavior can be explained by the formation of p-n heterojunction structures. A possible sensing mechanism is also illustrated, which can provide theoretical guidance for the further development of advanced gas-sensitive materials with p-n heterojunction.In this paper, we describe the design, fabrication and gas-sensing tests of nano-coaxial p-Co3O4/n-TiO2 heterojunction. Specifically, uniform TiO2 nanotubular arrays have been assembled by anodization and used as templates for generation of the Co3O4 one-dimensional nanorods. The structure morphology and composition of as-prepared products have been characterized by SEM, XRD, TEM, and XPS. A possible growth mechanism governing the formation of such nano-coaxial heterojunctions is proposed. The TiO2 nanotube sensor shows a normal n-type response to reducing ethanol gas, whereas TiO2-Co3O4 exhibits p-type response with excellent sensing performances. This conversion of sensing behavior can be explained by the formation of p-n heterojunction structures. A possible sensing mechanism is also illustrated, which can provide theoretical guidance for the further development of advanced gas-sensitive materials with p-n heterojunction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03616b

  2. Physico-chemical and NMR relaxometric characterization of gadolinium hydroxide and dysprosium oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Gossuin, Yves; Hocq, Aline; Vuong, Quoc Lam; Disch, Sabrina; Hermann, Raphaël P.; Gillis, Pierre

    2008-11-01

    Gadolinium hydroxide and dysprosium oxide nanoparticles, which constitute a new interesting class of magnetic nanoparticles, are characterized by different methods, using x-ray diffraction, magnetometry and NMR relaxometry at multiple fields. The rod-like particles are first shown to have a simple paramagnetic behavior, like the bulk compound, without any influence of the nanometric size of the particles. Because of their paramagnetic moment, these particles considerably shorten water relaxation times, especially the transverse relaxation time at high fields. The relaxation induced by gadolinium hydroxide particles is due to a proton exchange between the particle surface and bulk water, while the transverse relaxation caused by dysprosium oxide particles is governed by the diffusion of water protons around the magnetized particles. 1/T2 increases linearly with the magnetic field for gadolinium hydroxide particles while a quadratic increase is observed for dysprosium oxide nanoparticles. The relaxation results are compared with those from previous studies and interpreted using different theories for the relaxation induced by magnetic particles.

  3. Imaging the Three-Dimensional Conductive Channel in Filamentary-Based Oxide Resistive Switching Memory.

    PubMed

    Celano, Umberto; Goux, Ludovic; Degraeve, Robin; Fantini, Andrea; Richard, Olivier; Bender, Hugo; Jurczak, Malgorzata; Vandervorst, Wilfried

    2015-12-01

    Filamentary-based oxide resistive memory is considered as a disruptive technology for nonvolatile data storage and reconfigurable logic. Currently accepted models explain the resistive switching in these devices through the presence/absence of a conductive filament (CF) that is described as a reversible nanosized valence-change in an oxide material. During device operation, the CF cycles billion of times at subnanosecond speed, using few tens of microamperes as operating current and thus determines the whole device's performance. Despite its importance, the CF observation is hampered by the small filament size and its minimal compositional difference with the surrounding material. Here we show an experimental solution to this problem and provide the three-dimensional (3D) characterization of the CF in a scaled device. For this purpose we have recently developed a tomography technique which combines the high spatial resolution of scanning probe microscopy with subnanometer precision in material removal, leading to a true 3D-probing metrology concept. We locate and characterize in three-dimensions the nanometric volume of the conductive filament in state-of-the-art bipolar oxide-based devices. Our measurements demonstrate that the switching occurs through the formation of a single conductive filament. The filaments exhibit sizes below 10 nm and present a constriction near the oxygen-inert electrode. Finally, different atomic-size contacts are observed as a function of the programming current, providing evidence for the filament's nature as a defects modulated quantum contact. PMID:26523952

  4. Protecting BOPP film from UV degradation with an atomic layer deposited titanium oxide surface coating

    NASA Astrophysics Data System (ADS)

    Lahtinen, Kimmo; Maydannik, Philipp; Seppänen, Tarja; Cameron, David C.; Johansson, Petri; Kotkamo, Sami; Kuusipalo, Jurkka

    2013-10-01

    Titanium oxide layers were deposited onto a BOPP film by atomic layer deposition in order to prevent UV degradation of the film. The coatings were deposited in a low-temperature process at 80 °C by using tetrakis(dimethylamido)titanium and ozone as titanium and oxygen precursors, respectively. UV block characteristics of the coatings and their effect on the polymer were measured by using UV-vis and IR spectrometry, and differential scanning calorimetry. According to the results, the coatings provided a considerable decrease in the photodegradation of the BOPP film during UV exposure. IR spectra showed that during a 6-week UV exposure, a 67 nm titanium oxide coating was able to almost completely prevent the formation of photodegradation products in the film. The mechanical properties of the film were also protected by the coating, but as opposed to what the IR study suggested they were still somewhat compromised by the UV light. After a 6-week exposure, the tensile strength and elongation at break of the 67 nm titanium oxide coated film decreased to half of the values measured before the treatment. This should be compared to the complete degradation suffered by the uncoated base sheet already after only 4 weeks of treatment. The results show that nanometre scale inorganic films deposited by ALD show a promising performance as effective UV protection for BOPP substrates.

  5. DC-8-based observations of aircraft CO, CH4, N2O, and H2O(g) emission indices during SUCCESS

    NASA Astrophysics Data System (ADS)

    Vay, S. A.; Anderson, B. E.; Sachse, G. W.; Collins, J. E., Jr.; Podolske, J. R.; Twohy, C. H.; Gandrud, B.; Chan, K. R.; Baughcum, S. L.; Wallio, H. A.

    We report the first measurements of CO, CH4, N2O, CO2, and H2O(g) in the exhaust trails of T-39, B-757, and DC-8 aircraft at cruise conditions. Emission indices (EI) derived from these in-situ measurements are presented. Results are in agreement with ground-based tests indicating aircraft act as a net sink for CH4 and recent airborne in-situ measurements that N2O is not an important exhaust constituent. Condensation of H2O(g) on exhaust particles resulted in EI(H2O(g)) values less than those expected from the combustion of fuel alone. Observed apparent negative EI(H2O(g)) values suggest that aircraft aerosol emissions, under unique atmospheric conditions, seed cloud formation and lead to dehydration of the exhaust-influenced air parcel. Such conditions may induce the formation of cirrus clouds from persistent contrails. Comparisons with the Boeing EMIT Code show measurement-derived CO emission index values consistent with model evaluations.

  6. Electrical properties and conduction mechanism of [N(C2H5)4][N(CH3)4]CuCl4 compound

    NASA Astrophysics Data System (ADS)

    Drissi, N.; Karoui, K.; Jomni, F.; Rhaiem, A. Ben

    2016-09-01

    The [N(CH3)4][N(C2H5)4]CuCl4 single crystal has been synthetized in order to determinate the temperatures transition and to study the electrical properties and the conduction mechanism. At room temperature, this compound crystallizes in the tetragonal system with P-421m space group. The calorimetric study shows three anomalies at 248, 284 and 326 K. Electrical conduction and dielectrical relaxation mechanisms at various frequencies and temperatures were analyzed by impedance spectroscopy and the equivalent circuit based on the Z-View-software was proposed. The variation of fp relaxation determinate by the modulus study and σdc specific to the AC conductivity as a function of temperature and confirm the all transitions for our sample. The values of the activation energy are determined and compared by those, which are found in the similar compound. Frequencies dependence of alternative current (AC) conductivity is interpreted in terms of Jonscher's law and the conduction mechanisms for each phase are determined with the Elliot's theory.

  7. Multisite constrained model of trans-4-(N,N-dimethylamino)-4'-nitrostilbene for structural elucidation of radiative and nonradiative excited states.

    PubMed

    Lin, Cheng-Kai; Wang, Yu-Fu; Cheng, Yuan-Chung; Yang, Jye-Shane

    2013-04-18

    A constrained model compound of trans-4-(N,N-dimethylamino)-4'-nitrostilbene (DNS), namely, compound DNS-B3 that is limited to torsions about the phenyl-nitro C-N bond and the central C═C bond, was prepared to investigate the structural nature of the radiative and nonradiative states of electronically excited DNS. The great similarities in solvent-dependent electronic spectra, fluorescence decay times, and quantum yields for fluorescence (Φf) and trans → cis photoisomerization (Φtc) between DNS and DNS-B3 indicate that the fluorescence is from a planar charge-transfer state and torsion of the nitro group is sufficient to account for the nonradiative decay of DNS. This conclusion is supported by TDDFT calculations on DNS-B3 in dichloromethane. The structure at the conical intersection for internal conversion is associated with not only a twisting but also a pyramidalization of the nitro group. The mechanism of the NO2 torsion is discussed in terms of the effects of solvent polarity, the substituents, and the volume demand. The differences and analogies of the NO2- vs amino-twisted intramolecular charge-transfer (TICT) state of trans-aminostilbenes are also discussed.

  8. Electrorheological characterization of dispersions in silicone oil of encapsulated liquid crystal 4-n-penthyl-4‧-cyanobiphenyl in polyvinyl alcohol and in silica

    NASA Astrophysics Data System (ADS)

    Brehm, T.; Pereira, G.; Leal, C. R.; Gonçalves, C.; Borges, J. P.; Cidade, M. T.

    2015-03-01

    The electrorheological (ER) effect is known as the change in the apparent viscosity upon the application of an external electric field perpendicular to the flow direction. In this work we present the electrorheological behaviour of suspensions in silicone oil of two different dispersed phases: foams of liquid crystal 4-n-penthyl-4‧-cyanobiphenyl (5CB) encapsulated in polyvinyl alcohol (PVA) and nano/microspheres of 5CB encapsulated in silica. We will present the viscosity curves under the application of an electric field ranging between 0 and 3 kV mm-1. The ER effect was observed for the suspensions of 5CB/PVA but not in the case of 5CB/silica. For the case of the suspensions of 5CB/PVA, the effect of the viscosity of the continuum phase and the concentration of the dispersed phase was analysed, showing that the enhancement of the viscosity of the suspension increases with the concentration, as expected, however the continuum phase viscosity has no significant effect, at least in the investigated viscosity range.

  9. Synthesis, crystal structure, thermal analysis and dielectric properties of [(C4H9)4N]3Bi2Cl9 compound

    NASA Astrophysics Data System (ADS)

    Trigui, W.; Oueslati, A.; Chaabane, I.; Hlel, F.

    2015-07-01

    A new organic-inorganic tri-tetrabutylammonium nonachlorobibismuthate(III) compound was prepared. It was found to crystallize in the monoclinic system (P21/n space group) with the following lattice parameters: a=11.32(2) Å, b=22.30(3) Å, c=28.53(2) Å and β=96.52(0)°. The [Bi2Cl9]3- anions are surrounded by six [(C4H9)N]+ cations, forming an octahedral configuration. These octahedra are sharing corners in order to provide the tri-dimensional network cohesion. The differential scanning calorimetry reveals four order-disorder reversible phase transitions located at 214, 238, 434 and 477 K. The Raman and infrared spectra confirm the presence of both cationic [(C4H9)N]+ and anionic [Bi2Cl9]3- parts. The dielectric parameters, real and imaginary dielectric permittivity (ε‧ and ε″), and dielectric loss tangent (tg δ), were measured in the frequency range of 209 kHz-5 MHz at different temperatures. The variations of dielectric dispersion (ε') and dielectric absorption (ε″) with frequency show a distribution of relaxation times, which is probably related to the change in the dynamical state of the [(C4H9)4N]+ cations and the [Bi2Cl9]3- anions.

  10. Photodynamic Action Mechanism Mediated by Zinc(II) 2,9,16,23-Tetrakis[4-(N-methylpyridyloxy)]phthalocyanine in Candida albicans Cells.

    PubMed

    Di Palma, María Albana; Alvarez, María Gabriela; Durantini, Edgardo N

    2015-01-01

    The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc(4+) ) was studied in Candida albicans cells. This photosensitizer was strongly bound to C. albicans cells at short times. After 30 min irradiation, 5 μM ZnPPc(4+) produced ~5 log decrease in cell viability. Different probes were used to detect reactive oxygen species (ROS) in cell suspensions (~10(6) CFU mL(-1) ). Singlet molecular oxygen, O2 ((1) Δg ), was observed by the reaction with 9,10-dimethylanthracene (DMA) and tetrasodium 2,2-(anthracene-9,10-diyl)bis(methylmalonate) (ABMM), whereas the nitro blue tetrazolium (NBT) method was used to sense superoxide anion radical (O2·-). Moreover, the effects produced by an anoxic atmosphere and cell suspensions in D2 O, as well as the addition of sodium azide and mannitol as ROS trapping were evaluated in the PDI of C. albicans. These investigation indicates that O2 ((1) Δg ) is generated in the cells, although a minor extension other radical species can also be involved in the PDI of C. albicans mediated by ZnPPc(4+) . PMID:26108811

  11. Cross section limits for the {sup 248}Cm({sup 25}Mg,4n-5n){sup 268,269}Hs reactions

    SciTech Connect

    Dvorak, J.; Dvorakova, Z.; Schuber, R.; Tuerler, A.; Yakushev, A.; Bruechle, W.; Duellmann, Ch. E.; Jaeger, E.; Schaedel, M.; Schausten, B.; Schimpf, E.; Eberhardt, K.; Thoerle, P.; Eichler, R.; Nagame, Y.; Qin, Z.; Semchenkov, A.; Wegrzecki, M.

    2009-03-15

    We report on an attempt to produce and detect {sup 268}Hs and {sup 269}Hs in the nuclear fusion reaction {sup 25}Mg+{sup 248}Cm using the gas phase chemistry apparatus COMPACT. No decay chains attributable to the decay of hassium isotopes were observed during the course of this experiment. From the nonobservation of {sup 269}Hs we derive a cross section limit of 0.4 pb (63% confidence limit) for the reaction {sup 248}Cm({sup 25}Mg,4n){sup 269}Hs at a center-of-target beam energy of 140 MeV. The evaluated cross section limit for the {sup 248}Cm({sup 25}Mg,5n){sup 268}Hs reaction depends on the assumed half-life of unknown {sup 268}Hs. Current systematics of the half-lives for even-even Hs isotopes suggests a value of 0.5 s, resulting in a cross section limit of 1.3 pb.

  12. Methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan as a new chitosan derivative: Synthesis, characterization, cytotoxicity and antibacterial activity.

    PubMed

    Rahmani, Soheila; Mohammadi, Zohreh; Amini, Mohsen; Isaei, Elham; Taheritarigh, Sadegh; Rafiee Tehrani, Niyousha; Rafiee Tehrani, Morteza

    2016-09-20

    Chitosan, as a biocompatible polymer, is very attractive for biomedical applications. Continues studies are performing for improving its physicochemical features in order to make it more suitable for such approaches. In this study, methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan (MABCC) was synthesized,as a new chitosan derivative, in three steps. The investigations were carried out using FTIR, NMR, TGA and zeta potential measurement. Antibacterial and cell viability assessments were performed on four bacterial strains and two cell lines respectively. FTIR and NMR results showed that all substitution reactions were successfully carried out. Zeta potential of MABCC at various pH especially alkaline pH was greater than chitosan and it revealed increasing the solubility of the derivative. Antibacterial activity of MABCC was extremely greater than chitosan especially in Gram positive bacteria.Furthermore,it had no significant cytotoxicity against MCF-7 and Skov-3 cell lines in comparison to chitosan. These findings confirm that this new derivative can be introduced as a suitable compound for biomedical purposes.

  13. H-bond length dependence of the distortion in acid tetrahedron groups H nAsO 4 ( n=1-3)

    NASA Astrophysics Data System (ADS)

    Ichikawa, Mizuhiko

    1988-07-01

    The H-bond length O⋯O dependence of the distortions of the AsO 4 tetrahedra of acid arsenate groups H nAsO 4 ( n=1-3) have been studied by examining the correlations of the As sbnd O bond lengths, OAsO angles, O sbnd O lengths and Baur's distortion indices (DI) with O⋯O and comparing them with those of the corresponding H nPO 4 groups previously reported. The behavior of the O⋯O dependence of the AsO 4 distortion is analogous to that of PO 4 distortion as a whole, that is (a) all DI increase with increasing O⋯O, and correspondingly some of the individual or average As sbnd O lengths, OAsO angles and O sbnd O lengths correlate with O⋯O consistently; (b) the overall mean values of As sbnd O, OAsO and O sbnd O are reasonably constant in each H nAsO 4 type, most notably in the case of OAsO. The dependence of the PO 4 distortion on O⋯O can be described approximately by a model in which the P atom shifts away from the centroid of the regular tetrahedral framework, but the O⋯O dependence of the AsO 4 distortion is more complicated.

  14. Low Temperature Heat Capacities and Standard Molar Enthalpy of Formation of 2-Pyrazinecarboxylic Acid (C5H4N2O2)(s).

    PubMed

    Kong, Yu-Xia; Di, You-Ying; Yang, Wei-Wei; Gao, Sheng-Li; Tan, Zhi-Cheng

    2010-06-01

    Low-temperature heat capacities of 2-pyrazinecarboxylic acid (C5H4N2O2)(s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 10 K intervals. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision rotating-bomb combustion calorimeter to be ΔcU = -(17839.40 ± 7.40) J g-1. The standard molar enthalpy of combustion of the compound was determined to be ΔcH0m = -(2211.39 ± 0.92) KJ mol-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be ΔfH0m = -(327.82 ± 1.13) kJ mol-1 in accordance with Hess law. PMID:24061733

  15. beta1,4-N-Acetylglucosaminyltransferase III potentiates beta1 integrin-mediated neuritogenesis induced by serum deprivation in Neuro2a cells.

    PubMed

    Shigeta, Masaki; Shibukawa, Yukinao; Ihara, Hideyuki; Miyoshi, Eiji; Taniguchi, Naoyuki; Gu, Jianguo

    2006-06-01

    Aspects of the biological significance of the bisecting N-acetylglucosamine (GlcNAc) structure on N-glycans introduced by beta1,4-N-acetylglucosaminyltransferase III (GnT-III) in Neuro2a cell differentiation are demonstrated. The overexpression of GnT-III in the cells led to the induction of axon-like processes with numerous neurites and swellings, in which beta1 integrin was localized, under conditions of serum starvation. This enhancement in neuritogenesis was suppressed by either the addition of a bisecting GlcNAc-containing N-glycan or erythroagglutinating phytohemagglutinin (E(4)-PHA), which preferentially recognizes the bisecting GlcNAc. GnT-III-promoted neuritogenesis was also significantly perturbed by treatment with a functional blocking anti-beta1 integrin antibody. In fact, beta1 integrin was found to be one of the target proteins of GnT-III, as confirmed by a pull-down assay with E(4)-PHA. These data suggest that N-glycans with a bisecting GlcNAc on target molecules, such as beta1 integrin, play important roles in the regulation of neuritogenesis. PMID:16531477

  16. Thiol-reactive Derivatives of the Solvatochromic 4-N,N-Dimethylamino-1,8-naphthalimide Fluorophore: A Highly Sensitive Toolset for the Detection of Biomolecular Interactions

    PubMed Central

    Loving, Galen; Imperiali, Barbara

    2009-01-01

    The solvatochromic fluorophore 4-N,N-dimethylamino-1,8-naphthalimide (4-DMN) possesses extremely sensitive emission properties due largely to the low intrinsic fluorescence it exhibits in polar protic solvents like water. This makes it well suited as a probe for the detection of a wide range of biomolecular interactions. Herein we report the development and evaluation of a new series of thiol-reactive agents derived from this fluorophore. The members of this series vary according to linker type and the electrophilic group required for the labeling of proteins and other biologically relevant molecules. Using the calcium-binding protein calmodulin as a model system, we compare the performance of the 4-DMN derivatives to that of several commercially available solvatochromic fluorophores identifying many key factors import to the successful application of such tools. This study also demonstrates the power of this new series of labeling agents by yielding a fluorescent calmodulin construct capable of producing a greater than 100-fold increase in emission intensity upon binding to calcium. PMID:19821578

  17. Methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan as a new chitosan derivative: Synthesis, characterization, cytotoxicity and antibacterial activity.

    PubMed

    Rahmani, Soheila; Mohammadi, Zohreh; Amini, Mohsen; Isaei, Elham; Taheritarigh, Sadegh; Rafiee Tehrani, Niyousha; Rafiee Tehrani, Morteza

    2016-09-20

    Chitosan, as a biocompatible polymer, is very attractive for biomedical applications. Continues studies are performing for improving its physicochemical features in order to make it more suitable for such approaches. In this study, methylated 4-N,N dimethyl aminobenzyl N,O carboxymethyl chitosan (MABCC) was synthesized,as a new chitosan derivative, in three steps. The investigations were carried out using FTIR, NMR, TGA and zeta potential measurement. Antibacterial and cell viability assessments were performed on four bacterial strains and two cell lines respectively. FTIR and NMR results showed that all substitution reactions were successfully carried out. Zeta potential of MABCC at various pH especially alkaline pH was greater than chitosan and it revealed increasing the solubility of the derivative. Antibacterial activity of MABCC was extremely greater than chitosan especially in Gram positive bacteria.Furthermore,it had no significant cytotoxicity against MCF-7 and Skov-3 cell lines in comparison to chitosan. These findings confirm that this new derivative can be introduced as a suitable compound for biomedical purposes. PMID:27261738

  18. Synthesis, crystal structure, NMR study and AC conductivity of [(C3H7)4N]2Cd2ClF5 compound

    NASA Astrophysics Data System (ADS)

    Hajji, Rachid; Oueslati, Abderrazak; Body, Monique; Hlel, Faouzi

    2015-08-01

    The [(C3H7)4N]2Cd2ClF5 compound was crystallized in the triclinic system with space group P1. The crystal structure consists of organic-inorganic layers, stacked along direction. The organic part consists of two cations types. The inorganic layer is made up of Cd2ClF5 dimmers composed of two in-equivalent irregular tetrahedra sharing one edge (Cl-F). The MAS NMR spectra showed two, three and five isotropic resonances relative to 111Cd, 13C and 19F nuclei, respectively. DSC measurement disclosed a phase transition at around 380 K. The impedance spectroscopy and AC electrical conductivity measurements of our compound were taken from 209 Hz to 5 MHz over the temperature range of 350-381 K. Nyquist plots ( Z″ vs Z') show semicircle arcs at different temperatures, and an electrical equivalent circuit has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance ( R), capacitance ( C) and fractal capacitance (CPE). The conductivity σ p follows the Arrhenius relation. The near value of activation energies obtained from the conductivity data and circuit equivalent confirms that the transport is through hopping mechanism. The analysis of the experimental data shows that the reorientation motion of [N(C3H7)4]+ cations and/or [Cd2ClF5]2- anions is probably responsible for the observed conductivity.

  19. Raman study of order-disorder phase transition in [(C3H7)4N]3Bi3Cl12 compound

    NASA Astrophysics Data System (ADS)

    Trigui, W.; Oueslati, A.; Hlel, F.; Bulou, A.

    2016-02-01

    The [(C3H7)4N]3Bi3Cl12 compound that crystallizes at room temperature in a centrosymmetric triclinic system (P1bar space group) is studied on heating up to its melting temperature. Differential scanning calorimetry investigations disclosed an irreversible phase transition at T = 414 K. Raman scattering studies (140-3500 cm-1) were investigated in the temperature range 398-438 K. A detailed analysis of the frequency, half-width and reduced intensity of the bands associated to υ(Bi-Cl) (at 254 cm-1), υ(Bi-Cl) (at 287 cm-1) and υs(N-C-C)+δs(C-N-C) (at 1034 cm-1) is quantitatively described in term of an order-disorder phase transitions. The temperature dependence of the correlation lengths of these three bands is consistent with a disordered state at high temperature. This behavior is presumably governed by the reorientational motion of the alkylammonium chains of the cations between two sites coupled with changes of interactions with the anionic groups.

  20. Influence of aeration on CH4, N2O and NH3 emissions during aerobic composting of a chicken manure and high C/N waste mixture.

    PubMed

    Shen, Yujun; Ren, Limei; Li, Guoxue; Chen, Tongbin; Guo, Rui

    2011-01-01

    Co-composting of chicken manure, straw and dry grasses was investigated in a forced aeration system to estimate the effect of aeration rates on NH(3), CH(4) and N(2)O emissions and compost quality. Continuous measurements of gas emissions were carried out and detailed gas emission patterns were obtained using an intermittent-aeration of 30 min on/30 min off at rates of 0.01 (A1), 0.1 (A2) and 0.2 (A3) m(3)min(-1)m(-3). Concentrations of CH(4) and N(2)O at the low aeration rate (A1) were significantly greater than those at the other two rates, but there was no significant difference between the A2 and A3 treatments. CH(4) and N(2)O emissions for this mixture could be controlled when the composting process was aerobic and ammonia emissions were reduced at a lower aeration rate. Comparison of CH(4), N(2)O, NH(3) emissions and compost quality showed that the aeration rate of the A2 treatment was superior to the other two aeration rates. PMID:20888749

  1. Crystal structure of the human CD4 N-terminal two-domain fragment complexed to a class II MHC molecule.

    SciTech Connect

    Wang, J.-H.; Meijers, R.; Xiong, Y.; Liu, J.-H.; Sakihama, T.; Zhang, R.-G.; Joachimiak, A.; Reinherz, E. L.; Biosciences Division; Dana-Farber Cancer Inst.; Harvard Medical School

    2001-09-11

    The structural basis of the interaction between the CD4 coreceptor and a class II major histocompatibility complex (MHC) is described. The crystal structure of a complex containing the human CD4 N-terminal two-domain fragment and the murine I-A{sup k }class II MHC molecule with associated peptide (pMHCII) shows that only the 'top corner' of the CD4 molecule directly contacts pMHCII. The CD4 Phe-43 side chain extends into a hydrophobic concavity formed by MHC residues from both {alpha}2 and {beta}2 domains. A ternary model of the CD4-pMHCII-T-cell receptor (TCR) reveals that the complex appears V-shaped with the membrane-proximal pMHCII at the apex. This configuration excludes a direct TCR-CD4 interaction and suggests how TCR and CD4 signaling is coordinated around the antigenic pMHCII complex. Human CD4 binds to HIV gp120 in a manner strikingly similar to the way in which CD4 interacts with pMHCII. Additional contacts between gp120 and CD4 give the CD4-gp120 complex a greater affinity. Thus, ligation of the viral envelope glycoprotein to CD4 occludes the pMHCII-binding site on CD4, contributing to immunodeficiency.

  2. Measurements of CH4, N2O, CO, H2O and O3 in the middle atmosphere by the ATMOS experiment on Spacelab 3

    NASA Technical Reports Server (NTRS)

    Gunson, M. R.; Farmer, C. B.; Norton, R. H.; Zander, R.; Rinsland, C. P.; Shaw, J. H.; Gao, Bo-Cai

    1989-01-01

    The volume mixing ratios of five minor gases (CH4, N2O, CO, H2O, and O3) were retrieved through the middle atmosphere from the analysis of 0.01/cm resolution infrared solar occultation spectra recorded near 28 N and 48 S latitudes with the ATMOS (Atmospheric Trace Molecule Spectroscopy) instrument, flown on board Spacelab 3. The results, which constitute the first simultaneous observations of continuous profiles through the middle atmosphere for these gases, are in general agreement with reported measurements from ground, balloon and satellite-based instruments for the same seasons. In detail, the vertical profiles of these gases show the effects of the upper and middle atmospheric transport patterns dominant during the season of these observations. The profiles inferred at different longitudes around 28 N suggest a near-uniform zonal distribution of these gases. Although based on fewer observations, the sunrise occultation measurements point to a larger variability in the vertical distribution of these gases at 48 S.

  3. Seasonal changes of CO2, CH4, N2O, and SF6 in the upper troposphere/lower stratosphere over the Eurasian continent observed by commercial airliner

    NASA Astrophysics Data System (ADS)

    Sawa, Yousuke; Machida, Toshinobu; Matsueda, Hidekazu; Niwa, Yosuke; Tsuboi, Kazuhiro; Murayama, Shohei; Morimoto, Shinji; Aoki, Shuji

    2015-03-01

    The seasonal variations of greenhouse gases at about 11 km altitude were analyzed from monthly air samples collected aboard a commercial airliner flying between Europe and Japan from April 2012 to March 2014. Compared to lower latitudes, the upper troposphere between 50 and 70°N showed higher CH4 and SF6 and an earlier seasonal phase of CO2. However, N2O values were similar to those in the subtropics. CH4, N2O, and SF6 in the lower stratosphere with potential temperature of up to 50 K above the tropopause showed seasonal variations with maxima in November/December and minima in April/May. At potential temperatures of 37.5-50 K above the tropopause, SF6 age was estimated to be about 22 months in May and 9 months in November. This strong seasonal variation is explained by the subsidence of high-stratospheric air in spring and the effective flushing of the lowermost stratospheric air with tropospheric air in autumn.

  4. External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4'-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films.

    PubMed

    Furukawa, Kazuki; Hino, Kazuyuki; Yamamoto, Norifumi; Awasthi, Kamlesh; Nakabayashi, Takakazu; Ohta, Nobuhiro; Sekiya, Hiroshi

    2015-09-17

    The external electric field effects on the steady-state electronic spectra and excited-state dynamics were investigated for 4'-N,N-(dimethylamino)-3-hydroxyflavone (DMHF) in a poly(methyl methacrylate) (PMMA) film. In the steady-state spectrum, dual emission was observed from the excited states of the normal (N*) and tautomer (T*) forms. Application of an external electric field of 1.0 MV·cm(-1) enhanced the N* emission and reduced the T* emission, indicating that the external electric field suppressed the excited-state intramolecular proton transfer (ESIPT). The fluorescence decay profiles were measured for the N* and T* forms. The change in the emission intensity ratio N*/T* induced by the external electric field is dominated by ESIPT from the Franck-Condon excited state of the N* form and vibrational cooling in potential wells of the N* and T* forms occurring within tens of picoseconds. Three manifolds of fluorescent states were identified for both the N* and T* forms. The excited-state dynamics of DMHF in PMMA films has been found to be very different from that in solution due to intermolecular interactions in a rigid environment.

  5. Prognostic Value of Microvascular Density in Dukes A and B (T1–T4, N0, M0) Colorectal Carcinomas

    PubMed Central

    Uribarrena A, Rafael; Ortego, Javier; Fuentes, Javier; Raventós, Nuria; Parra, Pilar; Uribarrena E, Rafael

    2009-01-01

    Background. Aproximatelly 30% of patients operated on for colorectal cancer (CRC), with an expectedly favourable prognosis (Dukes A-B/T1–T4, N0, M0) suffer recurrence and/or die. Method. In order to determine if tumor microvascular density (MVD) is a prognostic factor in CRC, samples from tumors of 104 Dukes A-B CRC patients were retrospectively studied. Immunohistochemistry was performed for anti-CD34 antibody to visualize tumor vascularisation. MVD was expressed as the total number of vessels and as the percentage of microvascular area. We calculated MVD with a morphometry program and performed descriptive, bivariate, and survival statistics. Results. The mean number of vessels was 37.37/200x field, and the mean vascular area was the 3.972%. 30% of the patients with < 37 vessels/field, and 21% of the patients with > 37 vessels/field, experienced recurrence/death. The 35% of patients with < 4% of vascular area died following recurrence, compared with 14% of patients with ≥4% of vascular area. These differences in % of vascular area were statistically significant. Conclusion. MVD expressed as the total number of vessels had no a statistically significant influence on the evolution of CRC. However, neoplasias with a greater % of vascular were associated to a better outcome. PMID:19902004

  6. Relationship between molecular stacking and optical properties of 9,10-bis((4-N,N-dialkylamino)styryl) anthracene crystals: the cooperation of excitonic and dipolar coupling.

    PubMed

    Li, Feng; Gao, Na; Xu, Hai; Liu, Wei; Shang, Hui; Yang, Wenjun; Zhang, Ming

    2014-08-01

    Five 9,10-bis((4-N,N-dialkylamino)styryl) anthracene derivatives (DSA-C1-DSA-C7) with different length alkyl chains were synthesized. They showed the same color in dilute solutions but different colors in crystals. The absorption, photoluminescence, and fluorescence decay indicate that there exist both excitonic and dipolar coupling in crystals of DSA-C1-DSA-C7. X-ray crystallographic analysis revealed that all the crystals belong to the triclinic space group P1 with one molecule per unit cell and that the molecules in every crystal have the identical orientation. This offers ideal samples to investigate the impact of the molecular stacking on the optical properties of the crystals. For the first time, the cooperation of excitonic and dipolar coupling has been comprehensively studied, and the contribution to the spectral shift from the excitonic and dipolar couplings quantitatively obtained. The experiments of amplified spontaneous emission (ASE) together with measurements of the quantum efficiency further confirmed this interpretation. The results suggest that the excitonic and dipolar couplings between the adjacent molecules are both important and jointly induce the spectral shifts of the crystals.

  7. Comparative study of the electrical properties of Au/n-Si (MS) and Au/Si3N4/n-Si (MIS) Schottky diodes

    NASA Astrophysics Data System (ADS)

    Adem, Tataroğlu

    2013-06-01

    In this paper, the electrical parameters of Au/n-Si (MS) and Au/Si3N4/n-Si (MIS) Schottky diodes are obtained from the forward bias current—voltage (I—V) and capacitance—voltage (C—V) measurements at room temperature. Experimental results show that the rectifying ratios of the MS and MIS diodes at ± 5 V are found to be 1.25 × 103 and 1.27 × 104, respectively. The main electrical parameters of the MS and MIS diodes, such as the zero-bias barrier height (ΦBo) and ideality factor (n), are calculated to be 0.51 eV (I—V), 0.53 eV (C—V), and 4.43, and 0.65 eV (I—V), 0.70 eV (C—V), and 3.44, respectively. In addition, the energy density distribution profile of the interface states (Nss) is obtained from the forward bias I—V, and the series resistance (Rs) values for the two diodes are calculated from Cheung's method and Ohm's law.

  8. Ring-strain release in neutral and dicationic 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2.

    PubMed

    Scheidt, W Robert; Duval, Hugues F; Oliver, Allen G

    2016-06-01

    Two porphyrin complexes were studied to determine the effects of protonation on ring deformation within the porphyrin. The porphyrin 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin, C44H26Br4N4, was selected because the neutral species is readily doubly protonated to yield a dication, which was crystallized here with perchlorate counter-ions as a di-chloro-methane tris-olvate, C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2. The centrosymmetric neutral species is observed to have a mild 'ruffling' of the pyrrole rings and is essentially planar throughout; intra-molecular N-H⋯N hydrogen bonds occur. In contrast, the dication exhibits considerable deformation, with the pyrrole rings oriented well out of the plane of the porphyrin, resulting in a 'saddle' conformation of the ring. The charged species forms N-H⋯O hydrogen bonds to the perchlorate anions, which lie above and below the plane of the porphyrin ring. Distortions to the planarity of the pyrrole rings in both cases are very minor. The characterization of the neutral species represents a low-temperature redetermination of the previous room-temperature analyses [Zou et al. (1995 ▸). Acta Cryst. C51, 760-761; Rayati et al. (2008 ▸). Polyhedron, pp. 2285-2290], which showed disorder and physically unrealistic displacement parameters. PMID:27308051

  9. [Effect of dissolved oxygen on diversity of ammonia-oxidizing microorganisms in enrichment culture from estuarine wetland surface sediments and ammonia-oxidizing rate].

    PubMed

    Qiu, Zhao-Zheng; Luo, Zhuan-Xi; Zhao, Yan-Ling; Yan, Chang-Zhou

    2013-02-01

    Dissolved oxygen (DO) is one of the important environmental factors influencing the ammonia oxidation process. In order to examine the effects of DO on ammonia oxidation process and its potential mechanisms, surface sediments from Jiulong River Estuarine Wetland were collected and cultured to obtain enrichment cultures. Then the enrichment cultures were inoculated under different levels of DO, and the diversity of ammonia-oxidizing microorganisms was analyzed using PCR-DGGE technique to determine the effect of DO on the ammonia oxidation rate and the ammonia-oxidizing microorganism diversity. Results showed that the Shannon index was 2. 00 and 2.05 for ammonia-oxidizing bacteria (AOB) under saturated and aerobic conditions, respectively, and the values were 2.49 (saturated) and 2.03 (aerobic) for ammonia-oxidizing archaea (AOA). However, this index was 1.76 and 1.80 for AOB under hypoxia and anaerobic condition, and 1.27 and 2. 21 for AOA. Under saturated and aerobic conditions ( higher DO level), the ammonia-oxidizing rates were 14.20 mg.(L.d)-1 and 13.36 mg.(L.d)-1 and the related conversation rates of NH+4 -N were 93.8% and 88. 2% , respectively. In comparison, under hypoxia and anaerobic conditions (lower DO level), the ammonia-oxidizing rates were 7.82 mg.(L.d) -1 and 5.66 mg.(L.d)-1 and the related conversation rates of NH+4 -N were 51.7% and 37.4% , respectively. The correlation analysis showed that DO concentration was highly significantly positively correlated with the ammonia oxidation rate, and was significantly positively correlated with the AOB diversity index; DO and ammonia oxidation rate had no correlation with indices of AOA community.

  10. Radical Prostatectomy versus External Beam Radiotherapy for cT1-4N0M0 Prostate Cancer: Comparison of Patient Outcomes Including Mortality

    PubMed Central

    Taguchi, Satoru; Fukuhara, Hiroshi; Shiraishi, Kenshiro; Nakagawa, Keiichi; Morikawa, Teppei; Kakutani, Shigenori; Takeshima, Yuta; Miyazaki, Hideyo; Fujimura, Tetsuya; Nakagawa, Tohru; Kume, Haruki; Homma, Yukio

    2015-01-01

    Background Although radical prostatectomy (RP) and external beam radiotherapy (EBRT) have been considered as comparable treatments for localized prostate cancer (PC), it is controversial which treatment is better. The present study aimed to compare outcomes, including mortality, of RP and EBRT for localized PC. Methods We retrospectively analyzed 891 patients with cT1-4N0M0 PC who underwent either RP (n = 569) or EBRT (n = 322) with curative intent at our single institution between 2005 and 2012. Of the EBRT patients, 302 (93.8%) underwent intensity-modulated radiotherapy. Primary endpoints were overall survival (OS) and cancer-specific survival (CSS). Related to these, other-cause mortality (OCM) was also calculated. Biochemical recurrence-free survival was assessed as a secondary endpoint. Cox proportional hazards model was used for multivariate analysis. Results Median follow-up durations were 53 and 45 months, and median ages were 66 and 70 years (P <0.0001), in the RP and EBRT groups, respectively. As a whole, significantly better prognoses of the RP group than the EBRT group were observed for both OS and CSS, although OCM was significantly higher in the EBRT group. There was no death from PC in men with low and intermediate D’Amico risks, except one with intermediate-risk in the EBRT group. In high-risk patients, significantly more patients died from PC in the EBRT group than the RP group. Multivariate analysis demonstrated the RP group to be an independent prognostic factor for better CSS. On the other hand, the EBRT group had a significantly longer biochemical recurrence-free survival than the RP group. Conclusions Mortality outcomes of both RP and EBRT were generally favorable in low and intermediate risk patients. Improvement of CSS in high risk patients was seen in patients receiving RP over those receiving EBRT. PMID:26506569

  11. Nano-crystalline p-ZnGa{sub 2}Te{sub 4}/n-Si as a new heterojunction diode

    SciTech Connect

    Sakr, G.B.; Fouad, S.S.; Yahia, I.S.; Abdel Basset, D.M.; Yakuphanoglu, F.

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► ZnGa{sub 2}Te{sub 4}/Si thin film was prepared by thermal evaporation technique. ► XRD and AFM graphs support the nano-crystalline of the studied device. ► Dark current–voltage characteristics of the heterojunction diode were investigated. ► Electrical parameters and conduction mechanism were determined. ► Conduction mechanisms were controlled by TE, SCLC and TCLC. -- Abstract: In this communication, ZnGa{sub 2}Te{sub 4} thin film was prepared by thermal evaporation technique on n-Si substrate. P-ZnGa{sub 2}Te{sub 4}/n-Si heterojunction diode was fabricated. The structure of ZnGa{sub 2}Te{sub 4} thin film was checked by XRD pattern and confirmed by AFM micrographs. The dark current–voltage characteristics of the heterojunction diode were investigated to determine the electrical parameters and conduction mechanism as a function of forward and reverse biasing conditions in the range (−10 V to 10 V) at temperature interval (303–423 K). The conduction mechanism was controlled by thermionic emission, space charge limited (SCLC) and trap-charge limited current (TCLC) mechanisms. The basic parameters such as the series resistance R{sub s}, the shunt resistance R{sub sh}, the ideality factor n and the barrier height φ{sub b} of the diode, the total density of trap states N{sub 0} and the exponential trapping distribution P{sub o} were determined. The obtained results showed that ZnGa{sub 2}Te{sub 4} is a good candidate for the applications of electronic devices.

  12. PREFACE: Semiconducting oxides Semiconducting oxides

    NASA Astrophysics Data System (ADS)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  13. Layer structure: The oxides A 3Ti 5MO 14

    NASA Astrophysics Data System (ADS)

    Hervieu, M.; Rebbah, H.; Desgardin, G.; Raveau, B.

    1980-11-01

    Five new oxides, K 3Ti 5MO 14, Rb 3Ti 5MO 14 ( M = Ta, Nb), and Tl 3Ti 5NbO 14, have been synthesized. The structure of these oxides consists of octahedral layers similar to those observed for Na 2Ti 3O 7 and held together by monovalent ions; the sheets consist of blocks of 2 × 3 edge-sharing octahedra, which are then joined to each other by the corners of the octahedra. The relative disposition of the layers is similar to that observed for Tl 2Ti 4O 9. These oxides can be considered as the member n = 3 of a series of closely related structures with formula AnB2 nO 4 n+2 , where n indicates the number of octahedra which determines the width of the blocks of 2 × n octahedra.

  14. Ring-strain release in neutral and dicationic 7,8,17,18-tetra­bromo-5,10,15,20-tetra­phenyl­porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 2+·2ClO4 −·3CH2Cl2

    PubMed Central

    Scheidt, W. Robert; Duval, Hugues F.; Oliver, Allen G.

    2016-01-01

    Two porphyrin complexes were studied to determine the effects of protonation on ring deformation within the porphyrin. The porphyrin 7,8,17,18-tetra­bromo-5,10,15,20-tetra­phenyl­porphyrin, C44H26Br4N4, was selected because the neutral species is readily doubly protonated to yield a dication, which was crystallized here with perchlorate counter-ions as a di­chloro­methane tris­olvate, C44H28Br4N4 2+·2ClO4 −·3CH2Cl2. The centrosymmetric neutral species is observed to have a mild ‘ruffling’ of the pyrrole rings and is essentially planar throughout; intra­molecular N—H⋯N hydrogen bonds occur. In contrast, the dication exhibits considerable deformation, with the pyrrole rings oriented well out of the plane of the porphyrin, resulting in a ‘saddle’ conformation of the ring. The charged species forms N—H⋯O hydrogen bonds to the perchlorate anions, which lie above and below the plane of the porphyrin ring. Distortions to the planarity of the pyrrole rings in both cases are very minor. The characterization of the neutral species represents a low-temperature redetermination of the previous room-temperature analyses [Zou et al. (1995 ▸). Acta Cryst. C51, 760–761; Rayati et al. (2008 ▸). Polyhedron, pp. 2285–2290], which showed disorder and physically unrealistic displacement parameters. PMID:27308051

  15. Application of biofilm reactors to improve ammonia oxidation in low nitrogen loaded wastewater.

    PubMed

    Seca, I; Torres, R; Val del Río, A; Mosquera-Corral, A; Campos, J L; Méndez, R

    2011-01-01

    An airlift reactor using zeolite particles as carrier material was used for the nitrification of effluents from the aquaculture industry. During the start-up the nitrogen concentration was kept around 100 mg NH4(+)-N/L to develop the nitrifying population. Later it was decreased down to around 3 mg NH4(+)-N/L and the dilution rate was increased up to 4.8 d(-1) in order to simulate the conditions in a an aquaculture waster treatment system. A nitrogen loading rate (NLR) of 535 mg NH(+)-N/m2 d was fully oxidized to nitrate. Higher values of NLRs caused nitrite accumulation. A second biofilm reactor was fed with a synthetic medium containing 50 mg NH4(+)-N/L which simulated the effluents from anaerobic units treating domestic wastewater. A nitrogen loading rate of 400 mg NH4(+)-N/L d was oxidized into nitrate with an efficiency of 60% at a dilution rate of 8 d(-1). Both biofilm systems allowed the development of a nitrifying population to treat the studied types of wastewaters.

  16. Oxidation behavior of ferritic-martensitic and ODS steels in supercritical water

    NASA Astrophysics Data System (ADS)

    Bischoff, Jeremy

    water corroded much faster than those in steam (1.5 to 2 times faster). Additionally, during these corrosion tests a marker experiment was performed with the deposition of micrometric palladium markers on the surface of some samples prior to oxidation. The markers were found at the outer-inner layer interface, consistent with a corrosion mechanism of outward migration of iron to form the outer layer and inward migration of oxygen to form the inner layer. The discrepancy between the SCW and steam environments suggests that the outward migration of iron may be the rate-limiting step. A detailed study of the oxide advancement was performed using the TEM by analyzing the inner and diffusion layer structure. Energy-filtered TEM images were acquired to analyze the micrometric and nanometric distribution of elements in these layers. Such images from the inner layer revealed the presence of localized chromium enrichment regions associated with the presence of pores. Additionally, an iron-chromium nanometric segregation was observed and may be associated with the mixture of Fe3O4 and FeCr2O4. In the diffusion layer, small nanometric chromium-rich oxide particles were seen within metal grains. The (Fe,Cr)3O4 spinel oxide has an inverse spinel structure as Fe3O4 but becomes normal spinel as FeCr 2O4, thus the structure changes depending on the chromium content. Additionally, the spinel structure was analyzed using the ligand theory and showed that chromium does not migrate and that the main diffusing species is the Fe2+ ion. Calculations of the amount of iron leaving the inner layer showed that this amount accounted for the amount of iron necessary to form the outer layer, thus no dissolution of oxide in SCW is observed. Additionally, the differences in oxidation behavior in steam and SCW suggest that the rate-limiting step for the corrosion of ferritic-martensitic steels is the iron outward migration. The iron migration is driven by the gradient in the Fe2+/Fe 3+ ratio and is

  17. Oxide surfaces.

    PubMed

    Willmott, Phil

    2008-07-01

    Although the history of metal oxides and their surfaces goes back several decades to landmark studies, such as Mott and Peierls' explanation of electrical insulation in materials that are predicted in band theory to be conducting, or the observation by Morin of the superfast metal-to-insulator transition in vanadium dioxide, it is only in the last two decades that the world of condensed matter physics has become increasingly dominated by research into complex metal oxides. This has been driven most notably by an attempt to better understand and describe the fundamental physical processes behind their seemingly endless spectrum of properties, which in turn has also led to the discovery of novel phenomena, most prominently demonstrated by the discovery of high-temperature superconductivity in 1986, colossal magnetoresistance in 1994, and most recently, the formation of a two-dimensional conducting layer at the interface between two band insulators in 2004. One important reason why metal oxides, particularly in the form of thin films, have become such a popular subject for basic condensed matter research is that they offer a uniquely versatile materials base for the development of novel technologies. They owe this versatility both to the many different elemental combinations that lead to structurally similar forms, and also to the fact that in many cases, the strong interaction between the valence electrons means that there is a subtle interplay between structure and magnetic and electronic properties. This aspect has led in recent years to the birth or renaissance of research fields such as spintronics, orbital ordering, and multiferroics. Surfaces and interfaces are especially interesting in these strongly-correlated electron systems, where the rearrangement of electrical charge resulting from a minimization of surface or interfacial energy can have unexpected and often exciting consequences. Indeed, as the drive to miniaturize devices well below the micron size

  18. Nanostructured indium tin oxide slides for small-molecule profiling and imaging mass spectrometry of metabolites by surface-assisted laser desorption ionization MS.

    PubMed

    López de Laorden, Carlos; Beloqui, Ana; Yate, Luis; Calvo, Javier; Puigivila, Maria; Llop, Jordi; Reichardt, Niels-Christian

    2015-01-01

    Due to their electrical conductivity and optical transparency, slides coated with a thin layer of indium tin oxide (ITO) are the standard substrate for protein imaging mass spectrometry on tissue samples by MALDI-TOF MS. We have now studied the rf magnetron sputtering deposition parameters to prepare ITO thin films on glass substrates with the required nanometric surface structure for their use in the matrix-free imaging of metabolites and small-molecule drugs, without affecting the transparency required for classical histology. The custom-made surfaces were characterized by atomic force microscopy, scanning electron microscopy, ellipsometry, UV, and laser desorption ionization MS (LDI-MS) and employed for the LDI-MS-based analysis of glycans and druglike molecules, the quantification of lactose in milk by isotopic dilution, and metabolite imaging on mouse brain tissue samples. PMID:25411795

  19. Relativistic effects on nuclear magnetic shieldings of CHnX4-n and CHXYZ (X, Y, Z = H, F, Cl, Br, I)

    NASA Astrophysics Data System (ADS)

    Melo, Juan I.; Maldonado, Alejandro F.; Aucar, Gustavo A.

    2012-12-01

    Nuclear magnetic shieldings of both carbon and hydrogen atoms of haluro methyl molecules are highly influenced by the substitution of one or more hydrogen by halogen heavy atoms. We applied the linear response elimination of small components, LRESC, formalism to calculate such shieldings and learn whether including only few terms is enough for getting quantitative reproduction of the total shieldings or not. First, we discuss the contribution of all leading relativistic corrections to σ(C), in CHX2I molecular models with X = H, F, and Cl, and show that spin-orbit (SO) effects are the main ones. After adding the SO effects to the non-relativistic (NR) results, we obtain ˜ 97% (93%) of the total LRESC values for σ(C) (σ(H)). The magnitude of SO terms increases when the halogen atom becomes heavier. In this case, such contributions to σ(C) can be extrapolated as a function of Z, the halogen atomic number. Furthermore, when paramagnetic spin-orbit (PSO) contributions are also considered, we obtain results that are within 1% of the total LRESC value. Then we study in detail the main electronic mechanisms involved to contribute C and H shieldings on CHnX4 - n (n = 1, 3), and CHXYZ (X, Y, Z = F, Cl, Br, I) model compounds. The pattern of σ(C) for all series of compounds follows a normal halogen dependence (NHD), though with different rate of increase. A special family of compounds is that of CHF2X for which σnr(C) follows an inverse halogen dependence though the total shielding have a NHD due to the SO contributions. For the series CH3X (X = F, Cl, Br and I), we found that σSO ˜ Z_X^{2.53}. Another important finding of this work is the logarithmic dependence of σSO(C) with the substituent atomic number: ln σSO(C) = A_X + a_X Z_Y for both family of compounds CH2XY and CHX2Y. We also performed four-component calculations using the spin-free Hamiltonian to obtain SO contributions within a four-component framework.

  20. Drivers of small scale variability in soil-atmosphere fluxes of CH4, N2O and CO2 in a forest soil

    NASA Astrophysics Data System (ADS)

    Maier, Martin; Nicolai, Clara; Wheeler, Denis; Lang, Friedeike; Paulus, Sinikka

    2016-04-01

    Soil-atmosphere fluxes of CH4, N2O and CO2 can vary on different spatial scales, on large scales between ecosystems but also within apparently homogenous sites. While CO2 and CH4 consumption is rather evenly distibuted in well aerated soils, the production of N2O and CH4 seems to occur at hot spots that can be associated with anoxic or suboxic conditions. Small-scale variability in soil properties is well-known from field soil assesment, affecting also soil aeration and thus theoretically, greenhouse gas fluxes. In many cases different plant species are associated with different soil conditions and vegetation mapping should therefor combined with soil mapping. Our research objective was explaining the small scale variability of greenhouse gas fluxes in an apparently homogeneous 50 years old Scots Pine stand in a former riparian flood plain.We combined greenhouse gas measurements and soil physical lab measurments with field soil assessment and vegetation mapping. Measurements were conducted with at 60 points at a plot of 30 X 30 m at the Hartheim monitoring site (SW Germany). For greenhouse gas measurements a non-steady state chamber system and laser analyser, and a photoacoustic analyser were used. Our study shows that the well aerated site was a substantial sink for atmospheric CH4 (-2.4 nmol/m² s) and also a for N2O (-0.4 nmol/m² s), but less pronounced, whereas CO2 production was a magnitude larger (2.6 μmol/m² s). The spatial variability of the CH4 consumption of the soils could be explained by the variability of the soil gas diffusivity (measured in situ + using soil cores). Deviations of this clear trend were only observed at points where decomposing woody debris was directly under the litter layer. Soil texture ranged from gravel, coarse sand, fine sand to pure silt, with coarser texture having higher soil gas diffusivity. Changes in texture were rather abrupt at some positions or gradual at other positions, and were well reflected in the vegetation

  1. Relativistic effects on nuclear magnetic shieldings of CH(n)X(4-n) and CHXYZ (X, Y, Z = H, F, Cl, Br, I).

    PubMed

    Melo, Juan I; Maldonado, Alejandro F; Aucar, Gustavo A

    2012-12-01

    Nuclear magnetic shieldings of both carbon and hydrogen atoms of haluro methyl molecules are highly influenced by the substitution of one or more hydrogen by halogen heavy atoms. We applied the linear response elimination of small components, LRESC, formalism to calculate such shieldings and learn whether including only few terms is enough for getting quantitative reproduction of the total shieldings or not. First, we discuss the contribution of all leading relativistic corrections to σ(C), in CHX(2)I molecular models with X = H, F, and Cl, and show that spin-orbit (SO) effects are the main ones. After adding the SO effects to the non-relativistic (NR) results, we obtain ~ 97% (93%) of the total LRESC values for σ(C) (σ(H)). The magnitude of SO terms increases when the halogen atom becomes heavier. In this case, such contributions to σ(C) can be extrapolated as a function of Z, the halogen atomic number. Furthermore, when paramagnetic spin-orbit (PSO) contributions are also considered, we obtain results that are within 1% of the total LRESC value. Then we study in detail the main electronic mechanisms involved to contribute C and H shieldings on CH(n)X(4 - n) (n = 1, 3), and CHXYZ (X, Y, Z = F, Cl, Br, I) model compounds. The pattern of σ(C) for all series of compounds follows a normal halogen dependence (NHD), though with different rate of increase. A special family of compounds is that of CHF(2)X for which σ(nr)(C) follows an inverse halogen dependence though the total shielding have a NHD due to the SO contributions. For the series CH(3)X (X = F, Cl, Br and I), we found that σ(SO) ~ Z(X) (2.53). Another important finding of this work is the logarithmic dependence of σ(SO)(C) with the substituent atomic number: ln σ(SO)(C) = A(X) + a(X) Z(Y) for both family of compounds CH(2)XY and CHX(2)Y. We also performed four-component calculations using the spin-free Hamiltonian to obtain SO contributions within a four-component framework.

  2. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln==Sm, Eu, Gd) and [Ln(dien)2(1κ2-AsS4)] (Ln==Tb, Dy, Ho)

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-10-01

    Solvothermal reactions of Ln2O3, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien)2(μ-1κ,2κ2-AsS4)]n [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien)2(1κ2-AsS4)] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln2O3 oxides were converted to [Ln(dien)2]3+ complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS4 unit. In 1-3, the AsS4 units interconnect the [Ln(dien)2]3+ cations via Ln-S bonds as tridentate μ-1κ,2κ2-AsS4 bridging ligands, resulting in the neutral coordination polymers [Ln(dien)2(μ-1κ,2κ2-AsS4)]n (Ln1). In 4-6, the AsS4 units coordinate with the Ln3+ ion of [Ln(dien)2]3+ as 1κ2-AsS4 chelating ligands to form neutral coordination compounds [Ln(dien)2(1κ2-AsS4)] (Ln2). The Ln3+ ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln3+ ions. Optical absorption spectra showed that 1-6 have potential use as semiconductors with the band gaps in the range 2.18-3.21 eV.

  3. Study of uranium oxide milling in order to obtain nanostructured UCx target

    NASA Astrophysics Data System (ADS)

    Guillot, Julien; Tusseau-Nenez, Sandrine; Roussière, Brigitte; Barré-Boscher, Nicole; Brisset, François; Mhamed, Maher Cheikh; Lau, Christophe; Nowak, Sophie

    2016-05-01

    A R&D program is developed at the ALTO facility to provide new beams of exotic neutron-rich nuclei, as intense as possible. In the framework of European projects, it has been shown that the use of refractory targets with nanometric structure allows us to obtain beams of nuclei unreachable until now. The first parameter to be controlled in the processing to obtain targets with a homogeneous nanostructure is the grinding of uranium dioxide, down to 100 nm grain size. In this study, dry and wet grinding routes are studied and the powders are analyzed in terms of phase stabilization, specific surface area and grain morphology. It appears that the grinding, as well dry as wet, leads to the decrease of the particle size. The oxidation of UO2 is observed whatever the grinding. However, the dry grinding is the most efficient and leads to the oxidation of UO2 into U4O9 and U3O7 whose quantities increase with the grinding time while crystallite sizes decrease.

  4. Assisted deposition of nano-hydroxyapatite onto exfoliated carbon nanotube oxide scaffolds

    NASA Astrophysics Data System (ADS)

    Zanin, H.; Rosa, C. M. R.; Eliaz, N.; May, P. W.; Marciano, F. R.; Lobo, A. O.

    2015-05-01

    Electrodeposited nano-hydroxyapatite (nHAp) is more similar to biological apatite in terms of microstructure and dimension than apatites prepared by other processes. Reinforcement with carbon nanotubes (CNTs) enhances its mechanical properties and increases adhesion of osteoblasts. Here, we carefully studied nHAp deposited onto vertically aligned multi-walled CNT (VAMWCNT) scaffolds by electrodeposition and soaking in a simulated body fluid (SBF). VAMWCNTs are porous biocompatible scaffolds with nanometric porosity and exceptional mechanical and chemical properties. The VAMWCNT films were prepared on a Ti substrate by a microwave plasma chemical vapour deposition method, and then oxidized and exfoliated by oxygen plasma etching (OPE) to produce graphene oxide (GO) at the VAMWCNT tips. The attachment of oxygen functional groups was found to be crucial for nHAp nucleation during electrodeposition. A thin layer of plate-like and needle-like nHAp with high crystallinity was formed without any need for thermal treatment. This composite (henceforth referred to as nHAp-VAMWCNT-GO) served as the scaffold for in vitro biomineralization when soaked in the SBF, resulting in the formation of both carbonate-rich and carbonate-poor globular-like nHAp. Different steps in the deposition of biological apatite onto VAMWCNT-GO and during the short-term biomineralization process were analysed. Due to their unique structure and properties, such nano-bio-composites may become useful in accelerating in vivo bone regeneration processes.

  5. Thermal annealing and exposure to divertor-like deuterium plasma of tailored tungsten oxide coatings

    NASA Astrophysics Data System (ADS)

    Pezzoli, A.; Dellasega, D.; Russo, V.; Gallo, A.; Zeijlmans van Emmichoven, P. A.; Passoni, M.

    2015-08-01

    In this work we produced tungsten (W) and W oxide (WOx) films by pulsed laser deposition (PLD) with the aim of the addressing modifications of structure and morphology that occur after annealing treatments and high-flux deuterium plasma. Thanks to the high flexibility of PLD we produced nanostructured W containing non-bounded oxygen, different types of WOx and multilayered films. W coatings are dense, non-porous and exhibit a nanocrystalline structure, resembling the coatings used as first wall in tokamaks. The oxide films are nearly stoichiometric amorphous WOx (x = 3) with different morphology from compact to porous. Depending on annealing temperature, nucleation of different crystalline phases (e.g. WO3, W18O49) occurs. Exposure of films to high-flux (∼1024 m-2 s-1) deuterium plasmas in Magnum-PSI at different surface temperatures (Tmax = 580 K) determines material modifications at the nanoscale (e.g. nanometric defects) but no delamination. In addition preliminary deuterium retention results are reported.

  6. PREFACE: Semiconducting oxides Semiconducting oxides

    NASA Astrophysics Data System (ADS)

    Catlow, Richard; Walsh, Aron

    2011-08-01

    Semiconducting oxides are amongst the most widely studied and topical materials in contemporary condensed matter science, with interest being driven both by the fundamental challenges posed by their electronic and magnetic structures and properties, and by the wide range of applications, including those in catalysis and electronic devices. This special section aims to highlight recent developments in the physics of these materials, and to show the link between developing fundamental understanding and key application areas of oxide semiconductors. Several aspects of the physics of this wide and expanding range of materials are explored in this special section. Transparent semiconducting oxides have a growing role in several technologies, but challenges remain in understanding their electronic structure and the physics of charge carriers. A related problem concerns the nature of redox processes and the reactions which interconvert defects and charge carriers—a key issue which may limit the extent to which doping strategies may be used to alter electronic properties. The magnetic structures of the materials pose several challenges, while surface structures and properties are vital in controlling catalytic properties, including photochemical processes. The field profits from and exploits a wide range of contemporary physical techniques—both experimental and theoretical. Indeed, the interplay between experiment and computation is a key aspect of contemporary work. A number of articles describe applications of computational methods whose use, especially in modelling properties of defects in these materials, has a long and successful history. Several papers in this special section relate to work presented at a symposium within the European Materials Research Society (EMRS) meeting held in Warsaw in September 2010, and we are grateful to the EMRS for supporting this symposium. We would also like to thank the editorial staff of Journal of Physics: Condensed Matter for

  7. Cellular and humoral mediated immunity and distribution of viral antigen in chickens after infection with a low pathogenic avian influenza virus (H4N6) isolated from wild ducks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four-week-old commercial chickens were intranasally inoculated with an H4N6 low pathogenicity avian influenza virus (LPAIV) isolated from a duck in Ukraine. Cecum, spleen, lung, and trachea samples were collected from birds from 1 to 21 days post inoculation (dpi) and examined by immunohistochemica...

  8. Preparation of periodic mesoporous silica-included divacant Keggin units for the catalytic oxidation of styrene to synthesize styrene oxide

    NASA Astrophysics Data System (ADS)

    Yu, Xiaodan; Xu, Leilei; Yang, Xia; Guo, Yingna; Li, Kexin; Hu, Jianglei; Li, Wei; Ma, Fengyan; Guo, Yihang

    2008-05-01

    Periodic mesoporous composite catalysts, [( n-C 4H 9) 4N] 4[γ-SiW 10O 34(H 2O) 2]/SBA-15 (TBA-1*/SBA-15, where TBA-1* = [( n-C 4H 9) 4N] 4[γ-SiW 10O 34(H 2O) 2]), with TBA-1* loadings of 4.3-14.8% were prepared by simultaneous hydrolysis and co-condensation of the tetraethoxysilane (TEOS) in the presence of divacant Keggin-type polyoxometalate and triblock copolymer surfactant (P123) followed by hydrothermal treatment process. Structure integrity of the Keggin unit in as-prepared composites was studied by Fourier transform infrared spectroscopy (FT-IR), Raman scattering spectra, and 29Si magic-angle spinning (MAS) NMR. Periodic mesoporous structure of the composites was evaluated by low-angle X-ray powder diffraction (LXRD) patterns, nitrogen porosimetry, and transmission electron microscope (TEM) measurements. As-prepared TBA-1*/SBA-15 was used as an heterogeneous oxidation catalyst for the styrene epoxidation reaction to synthesize styrene oxide in the presence of dilute H 2O 2 (30%), and influences of solvent, molar ratio of styrene to H 2O 2, TBA-1* loading on the styrene conversion, styrene oxide yield and selectivity were considered.

  9. Synthesis and Structural Elucidation of Triazolylmolybdenum(VI) Oxide Hybrids and Their Behavior as Oxidation Catalysts.

    PubMed

    Lysenko, Andrey B; Senchyk, Ganna A; Domasevitch, Konstantin V; Hauser, Jürg; Fuhrmann, Daniel; Kobalz, Merten; Krautscheid, Harald; Neves, Patrícia; Valente, Anabela A; Gonçalves, Isabel S

    2015-09-01

    A large family of bifunctional 1,2,4-triazole molecular tectons (tr) has been explored for engineering molybdenum(VI) oxide hybrid solids. Specifically, tr ligands bearing auxiliary basic or acidic groups were of the type amine, pyrazole, 1H-tetrazole, and 1,2,4-triazole. The organically templated molybdenum(VI) oxide solids with the general compositions [MoO3(tr)], [Mo2O6(tr)], and [Mo2O6(tr)(H2O)2] were prepared under mild hydrothermal conditions or by refluxing in water. Their crystal structures consist of zigzag chains, ribbons, or helixes of alternating cis-{MoO4N2} or {MoO5N} polyhedra stapled by short [N-N]-tr bridges that for bitriazole ligands convert the motifs into 2D or 3D frameworks. The high thermal (235-350 °C) and chemical stability observed for the materials makes them promising for catalytic applications. The molybdenum(VI) oxide hybrids were successfully explored as versatile oxidation catalysts with tert-butyl hydroperoxide (TBHP) or aqueous H2O2 as an oxygen source, at 70 °C. Catalytic performances were influenced by the different acidic-basic properties and steric hindrances of coordinating organic ligands as well as the structural dimensionality of the hybrid. PMID:26280712

  10. A novel yellow-emitting SrAlSi{sub 4}N{sub 7}:Ce{sup 3+} phosphor for solid state lighting: Synthesis, electronic structure and photoluminescence properties

    SciTech Connect

    Ruan, Jian; Xie, Rong-Jun; Funahashi, Shiro; Tanaka, Yoshinori; Takeda, Takashi; Suehiro, Takayuki; Hirosaki, Naoto; Li, Yuan-Qiang

    2013-12-15

    Ce{sup 3+}-doped and Ce{sup 3+}/Li{sup +}-codoped SrAlSi{sub 4}N{sub 7} phosphors were synthesized by gas pressure sintering of powder mixtures of Sr{sub 3}N{sub 2}, AlN, α-Si{sub 3}N{sub 4}, CeN and Li{sub 3}N. The phase purity, electronic crystal structure, photoluminescence properties of SrAlSi{sub 4}N{sub 7}:Ce{sup 3+}(Ce{sup 3+}/Li{sup +}) were investigated in this work. The band structure calculated by the DMol{sup 3} code shows that SrAlSi{sub 4}N{sub 7} has a direct band gap of 3.87 eV. The single crystal analysis of Ce{sup 3+}-doped SrAlSi{sub 4}N{sub 7} indicates a disordered Si/Al distribution and nitrogen vacnacy defects. SrAlSi{sub 4}N{sub 7} was identified as a major phase of the fired powders, and Sr{sub 5}Al{sub 5}Si{sub 21}N{sub 35}O{sub 2} and AlN as minor phases. Both Ce{sup 3+} and Ce{sup 3+}/Li{sup +} doped SrAlSi{sub 4}N{sub 7} phosphors can be efficiently excited by near-UV or blue light and show a broadband yellow emission peaking around 565 nm. A highest external quantum efficiency of 38.3% under the 450 nm excitation was observed for the Ce{sup 3+}/Li{sup +}-doped SrAlSi{sub 4}N{sub 7} (5 mol%). A white light LED lamp with color temperature of 6300 K and color rendering index of Ra=78 was achieved by combining Sr{sub 0.97}Al{sub 1.03}Si{sub 3.997}N/94/maccounttest14=t0005{sub 1}8193 {sub 7}:Ce{sup 3+}{sub 0.03} with a commercial blue InGaN chip. It indicates that SrAlSi{sub 4}N{sub 7}:Ce{sup 3+} is a promising yellow emitting down-conversion phosphor for white LEDs. - Graphical abstract: One-phosphor converted white light-emitting diode (LED) was fabricated by combining a blue LED chip and a yellow-emitting SrAlSi4N7:Ce{sup 3+} phosphor (see inset), which has the color rendering index of 78 and color temperature of 6300 K. - Highlights: • We reported a new yellow nitride phosphor suitable for solid state lighting. • We solved the crystal structure and evidenced a disordered Si/Al distribution. • We fabricated a high color rendering

  11. Lorentz transmission electron microscopy on nanometric magnetic bubbles and skyrmions in bilayered manganites La{sub 1.2}Sr{sub 1.8}(Mn{sub 1−y}Ru{sub y}){sub 2}O{sub 7} with controlled magnetic anisotropy

    SciTech Connect

    Morikawa, D.; Yu, X. Z.; Kaneko, Y.; Tokunaga, Y.; Arima, T.; Nagai, T.; Kimoto, K.; Tokura, Y.

    2015-11-23

    We have investigated nanometric magnetic textures in thin (<150 nm) plates of Ru-doped bilayered manganites La{sub 1.2}Sr{sub 1.8}(Mn{sub 1−y}Ru{sub y}){sub 2}O{sub 7}. Ru substitution for Mn site changes the magnetic anisotropy from in-plane to out-of-plane easy axis type without any significant change of global magnetic and crystal structures. The combination of conventional and Lorentz transmission electron microscopy observations confirms the emergence of magnetic bubbles and skyrmions in the absence of magnetic field. With the changing Ru concentration, systematic changes in the type of magnetic bubbles are observed. A tiny residual magnetic field also affects the generation and the type-change of magnetic bubbles.

  12. Ionic liquids as unique solvents in one-pot synthesis of 4-(n,2,2,2-tetranitroethylamino)-3-R-furazans.

    PubMed

    Sheremetev, Aleksei B; Aleksandrova, Nataly S; Palysaeva, Nadezhda V; Struchkova, Marina I; Tartakovsky, Vladimir A; Suponitsky, Kyrill Yu

    2013-09-01

    An efficient two-step one-pot protocol for the synthesis of N-nitrated trinitroethylamino furazans in an ionic liquid has been developed involving the condensation of aminofurazans with trinitroethanol and the N-nitration of an intermediate Mannich base. Trinitroethylnitramino derivatives have been synthesized and characterized by multinuclear NMR spectroscopy and X-ray crystallography. A role of the N,2,2,2-tetranitroethylamino group for stabilization of the high-density crystal-packing motif is described. The performance calculations gave detonation pressures and velocities for the furazan derivatives in a range of about 31-36 GPa and 8330-8745 ms(-1), respectively, which makes them competitive energetic materials. Furthermore, due to the positive oxygen balance, the compounds could be potential oxidizers for energetic formulations.

  13. Structure of the Escherichia coli ArnA N-formyltransferase domain in complex with N(5) -formyltetrahydrofolate and UDP-Ara4N.

    PubMed

    Genthe, Nicholas A; Thoden, James B; Holden, Hazel M

    2016-08-01

    ArnA from Escherichia coli is a key enzyme involved in the formation of 4-amino-4-deoxy-l-arabinose. The addition of this sugar to the lipid A moiety of the lipopolysaccharide of pathogenic Gram-negative bacteria allows these organisms to evade the cationic antimicrobial peptides of the host immune system. Indeed, it is thought that such modifications may be responsible for the repeated infections of cystic fibrosis patients with Pseudomonas aeruginosa. ArnA is a bifunctional enzyme with the N- and C-terminal domains catalyzing formylation and oxidative decarboxylation reactions, respectively. The catalytically competent cofactor for the formylation reaction is N(10) -formyltetrahydrofolate. Here we describe the structure of the isolated N-terminal domain of ArnA in complex with its UDP-sugar substrate and N(5) -formyltetrahydrofolate. The model presented herein may prove valuable in the development of new antimicrobial therapeutics.

  14. Effects of Elevated CO2 on Soil Trace Gas (CH4, N2O and NO) Fluxes in a Scrub Oak Ecosystem at Kennedy Space Center, FL, USA

    NASA Astrophysics Data System (ADS)

    Hartley, A. E.; Bracho, R. G.; Stover, D.

    2008-05-01

    Rising atmospheric CO2 concentrations increase the plant demand for soil nutrients, which in turn can impose a nitrogen limitation on unmanaged ecosystems. The microbial responses to CO2 enrichment are complex and difficult to predict. Some studies suggest that CO2 enrichment increases microbial mineralization of nitrogen, making nitrogen more available through a carbon priming effect. Alternatively, microbes may contribute to nitrogen limitation through accelerated soil nitrogen losses. In this study, we examined the effects of CO2 enrichment on trace gases that are released or taken up during soil microbial reactions: nitrification, denitrification and methane consumption. Ambient and approximately twice-ambient CO2 treatments were applied to a coastal scrub oak community at Kennedy Space Center, FL, via open-top chambers since May 1996. The CO2 treatments ended in July 2007 before an aboveground harvest took place inside the chambers. Nitrous oxide (N2O), nitric oxide (NO) and methane (CH4) fluxes were measured in the field from 2006-2008. Soil N2O losses from the study site were low (< 1 ng N2O-N cm-2 h-1) with no CO2 treatment effect. Soil NO losses were similarly low (< 1 ng N2O-N cm-2 h-1), but fluxes were consistently lower in elevated CO2 than in ambient CO2. NO production was higher for 3 months post-harvest in ambient CO2. Methane consumption was lower in elevated vs. ambient CO2 in 2006, although this trend was not significant. Over a decade of CO2 enrichment has reduced soil nitrogen availability, which could explain the low overall rates of nitrogen trace gas emission. Reduced soil carbon stores in elevated CO2 measured at this site could also explain the lower nitrification rates, measured as NO efflux. Trace gas emissions in this sandy, nutrient-poor scrub oak forest are comparable to published rates in desert ecosystems.

  15. Strength by atomic force microscopy (AFM): Molecular dynamics of water layer squeezing on magnesium oxide

    NASA Astrophysics Data System (ADS)

    Kendall, K.; Dhir, Aman; Yong, Chin W.

    2010-11-01

    Localised strength testing of materials is often carried out in an atomic force microscope (AFM), as foreseen by Kelly in his book Strong Solids (Clarendon Press, Oxford, 1966). During AFM indentation experiments, contamination can strongly influence the observed strength and theoretical interpretation of the results is a major problem. Here, we use molecular dynamics computer modelling to describe the contact of NaCl and MgO crystal probes onto surfaces, comparable to an AFM experiment. Clean NaCl gave elastic, brittle behaviour in contact simulations at 300 K, whereas MgO was more plastic, leading to increased toughness. This paper also considers the strength of an oxide substrate contaminated by water molecules and tested by indentation with a pyramidal probe of oxide crystal. Recent theory on the effect of liquid contaminant layers on surface strength has been mainly focussed on Lennard Jones (LJ) molecules with some studies on alcohols and water, described by molecular dynamics, which allows the molecules to be squeezed out as the crystal lattice is deformed. In this work, we have focused on water by studying the forces between a magnesium oxide (MgO) atomic force microscope (AFM) probe and an MgO slab. Force versus separation has been plotted as the AFM probe was moved towards and away from the substrate. Simulation results showed that the water layers could be removed in steps, giving up to four force peaks. The last monolayer of water could not be squeezed out, even at pressures where MgO deformed plastically. Interestingly, with water present, strength was reduced, but more in tensile than compressive measurements. In conclusion, water contaminating the oxide surface in AFM strength testing is structured. Water layer squeezing removal can be predicted by molecular modelling, which may be verified by AFM experiments to show that water can influence the strength of perfect crystals at the nanometre scale.

  16. Physical properties of superbulky lanthanide metallocenes: synthesis and extraordinary luminescence of [Eu(II)(Cp(BIG))2] (Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl).

    PubMed

    Harder, Sjoerd; Naglav, Dominik; Ruspic, Christian; Wickleder, Claudia; Adlung, Matthias; Hermes, Wilfried; Eul, Matthias; Pöttgen, Rainer; Rego, Daniel B; Poineau, Frederic; Czerwinski, Kenneth R; Herber, Rolfe H; Nowik, Israel

    2013-09-01

    The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-α-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)⋅⋅⋅Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mössbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215 K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203 K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8 eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100 K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature

  17. Micro-arc oxidation as a tool to develop multifunctional calcium-rich surfaces for dental implant applications.

    PubMed

    Ribeiro, A R; Oliveira, F; Boldrini, L C; Leite, P E; Falagan-Lotsch, P; Linhares, A B R; Zambuzzi, W F; Fragneaud, B; Campos, A P C; Gouvêa, C P; Archanjo, B S; Achete, C A; Marcantonio, E; Rocha, L A; Granjeiro, J M

    2015-09-01

    Titanium (Ti) is commonly used in dental implant applications. Surface modification strategies are being followed in last years in order to build Ti oxide-based surfaces that can fulfill, simultaneously, the following requirements: induced cell attachment and adhesion, while providing a superior corrosion and tribocorrosion performance. In this work micro-arc oxidation (MAO) was used as a tool for the growth of a nanostructured bioactive titanium oxide layer aimed to enhance cell attachment and adhesion for dental implant applications. Characterization of the surfaces was performed, in terms of morphology, topography, chemical composition and crystalline structure. Primary human osteoblast adhesion on the developed surfaces was investigated in detail by electronic and atomic force microscopy as well as immunocytochemistry. Also an investigation on the early cytokine production was performed. Results show that a relatively thick hybrid and graded oxide layer was produced on the Ti surface, being constituted by a mixture of anatase, rutile and amorphous phases where calcium (Ca) and phosphorous (P) were incorporated. An outermost nanometric-thick amorphous oxide layer rich in Ca was present in the film. This amorphous layer, rich in Ca, improved fibroblast viability and metabolic activity as well as osteoblast adhesion. High-resolution techniques allowed to understand that osteoblasts adhered less in the crystalline-rich regions while they preferentially adhere and spread over in the Ca-rich amorphous oxide layer. Also, these surfaces induce higher amounts of IFN-γ cytokine secretion, which is known to regulate inflammatory responses, bone microarchitecture as well as cytoskeleton reorganization and cellular spreading. These surfaces are promising in the context of dental implants, since they might lead to faster osseointegration. PMID:26046283

  18. Oxidation resistance of silicon ceramics

    NASA Technical Reports Server (NTRS)

    Yasutoshi, H.; Hirota, K.

    1984-01-01

    Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented graphically. An assessment is made of the oxidation process, and an oxidation example of silicon ceramics is given.

  19. Signal transduction pathways in erythrocyte nitric oxide metabolism under high fibrinogen levels

    NASA Astrophysics Data System (ADS)

    Saldanha, Carlota; Freitas, T.; Lopez de Almeida, J. P.; Silva-Herdade, A.

    2014-05-01

    Previous studies show that the fibrinogen molecule modulates the metabolism of nitric oxide (NO) in erythrocyte. The in vitro induced hiperfibrinogenemia interferes in the metabolism of the NO in the erythrocyte in dependence of the phosphorylation degree of the band 3. The soluble form of fibrinogen binds into CD47 protein present in the erythrocyte membrane. The soluble thrombomodulin is an inflammatory marker that binds to the erythrocyte CD47 in a site with a sequence peptide known as 4N1K. A study done in vitro shows that when hiperfibrinogenemia was induced in the presence of the peptide 4N1K agonist of CD47 it were observed variations in the efflux of NO from erythrocyte and an increase in the concentrations of GSNO, peroxinitrite, nitrite and nitrate of the erythrocytes. The aim of this work was to study the influence of the peptide 4N1K, on the metabolism of NO in the erythrocyte under high fibrinogen concentration and in the presence of inhibitors of the status of phosphorylation of protein band 3. In this in vitro study, whole blood samples were harvested from healthy subjects and NO, peroxynitrite, nitrite, nitrate and S-nitro-glutathione (GSNO) were determined in presence of 4N1K, calpeptine, Syk inhibitor and under high fibrinogen concentrations. The results obtained in erythrocytes under high fibrinogen levels when 4N1K is present with the Syk inhibitor or with calpeptine, showed in relation to the control samples increased significant concentrations of efflux of NO and of peroxynitrite, nitrite, nitrate and GSNO. In conclusion it was verified that in the in vitro model of hiperfibrinogenemia the peptide 4N1K, agonist of CD47, induces mobilization of NO in the erythrocyte in dependence of the status of phosphorylation of protein band 3.

  20. Nitric oxide inhibition strategies

    PubMed Central

    Wong, Vivian (Wai Chong); Lerner, Ethan

    2015-01-01

    Nitric oxide is involved in many physiologic processes. There are efforts, described elsewhere in this volume, to deliver nitric oxide to tissues as a therapy. Nitric oxide also contributes to pathophysiologic processes. Inhibiting nitric oxide or its production can thus also be of therapeutic benefit. This article addresses such inhibitory strategies. PMID:26634146

  1. Electrochemical oxidation of cholesterol

    PubMed Central

    2015-01-01

    Summary Indirect cholesterol electrochemical oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and affords different products depending on the reaction conditions. PMID:25977713

  2. Thermally exfoliated graphite oxide

    NASA Technical Reports Server (NTRS)

    Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor); Abdala, Ahmed (Inventor)

    2011-01-01

    A modified graphite oxide material contains a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, wherein the thermally exfoliated graphite oxide displays no signature of the original graphite and/or graphite oxide, as determined by X-ray diffraction.

  3. Improvement of the electron collection efficiency in porous hematite using a thin iron oxide underlayer: towards efficient all-iron based photoelectrodes.

    PubMed

    Dalle Carbonare, Nicola; Carli, Stefano; Argazzi, Roberto; Orlandi, Michele; Bazzanella, Nicola; Miotello, Antonio; Caramori, Stefano; Bignozzi, Carlo A

    2015-11-28

    Different approaches have been explored to increase the water oxidation activity of nanostructured hematite (α-Fe2O3) photoanodes, including doping with various elements, surface functionalization with both oxygen evolving catalysts (OEC) and functional overlayers and, more recently, the introduction of ultrathin oxide underlayers as tunneling back contacts. Inspired by this latter strategy, we present here a photoanode design with a nanometric spin-coated iron oxide underlayer coupled with a mesoporous hematite film deposited by electrophoresis. The electrodes equipped with the thin underlayer exhibit a four-fold improvement in photoactivity over the simple hematite porous film, reaching a stable photocurrent density of ca. 1 mA cm(-2) at 0.65 V versus the saturated calomel electrode (SCE) at pH 13.3 (NaOH 0.1 M) under air mass (AM) 1.5G illumination. A further improvement to 1.5 mA cm(-2) is observed after decoration of the hematite surface with a Fe(iii)-OEC. These results demonstrate that by combining different iron oxide morphologies, it is possible to improve the selectivity of the interfaces towards both electron collection at the back contact and hole transfer to the electrolyte, obtaining an efficient all-iron based photoelectrode entirely realized with simple wet solution scalable procedures. PMID:26477966

  4. Photo-oxidation catalysts

    DOEpatents

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  5. The Enzymatic Oxidation of Graphene Oxide

    PubMed Central

    Kotchey, Gregg P.; Allen, Brett L.; Vedala, Harindra; Yanamala, Naveena; Kapralov, Alexander A.; Tyurina, Yulia Y.; Klein-Seetharaman, Judith; Kagan, Valerian E.; Star, Alexander

    2011-01-01

    Two-dimensional graphitic carbon is a new material with many emerging applications, and studying its chemical properties is an important goal. Here, we reported a new phenomenon – the enzymatic oxidation of a single layer of graphitic carbon by horseradish peroxidase (HRP). In the presence of low concentrations of hydrogen peroxide (~40 µM), HRP catalyzed the oxidation of graphene oxide, which resulted in the formation of holes on its basal plane. During the same period of analysis, HRP failed to oxidize chemically reduced graphene oxide (RGO). The enzymatic oxidation was characterized by Raman, UV-Vis, EPR and FT-IR spectroscopy, TEM, AFM, SDS-PAGE, and GC-MS. Computational docking studies indicated that HRP was preferentially bound to the basal plane rather than the edge for both graphene oxide and RGO. Due to the more dynamic nature of HRP on graphene oxide, the heme active site of HRP was in closer proximity to graphene oxide compared to RGO, thereby facilitating the oxidation of the basal plane of graphene oxide. We also studied the electronic properties of the reduced intermediate product, holey reduced graphene oxide (hRGO), using field-effect transistor (FET) measurements. While RGO exhibited a V-shaped transfer characteristic similar to a single layer of graphene that was attributed to its zero band gap, hRGO demonstrated a p-type semiconducting behavior with a positive shift in the Dirac points. This p-type behavior rendered hRGO, which can be conceptualized as interconnected graphene nanoribbons, as a potentially attractive material for FET sensors. PMID:21344859

  6. Dielectric barrier discharge plasma treatment on E. coli: Influence of CH{sub 4}/N{sub 2}, O{sub 2}, N{sub 2}/O{sub 2}, N{sub 2}, and Ar gases

    SciTech Connect

    Majumdar, Abhijit; Hippler, Rainer; Singh, Rajesh Kumar; Palm, Gottfried J.

    2009-10-15

    Atmospheric pressure dielectric barrier discharge (DBD) plasma has been employed on Gram-negative bacteria, Escherichia coli BL21. Treatment was carried out using plasma generated with different compositions of gases: CH{sub 4}/N{sub 2} (1:2), O{sub 2}, N{sub 2}/O{sub 2} (1:1), N{sub 2}, and Ar, and by varying plasma power and treatment time. E. coli cells were exposed under the DBD plasma in triplicates, and their surviving numbers were observed in terms of colony forming units. It has been observed that the CH{sub 4}/N{sub 2} plasma exhibits relatively higher sterilization property toward E. coli compared to plasma generated by using O{sub 2}, N{sub 2}/O{sub 2}, N{sub 2}, and Ar gas mixtures. The time to kill up to 90% of the initial population of the E. coli cells was found to be about 2-3 min for CH{sub 4}/N{sub 2} and O{sub 2} gas mixture DBD plasma. A prolongation of treatment time and an increase in the dissipated power significantly improved the E. coli killing efficiency of the atmospheric pressure DBD plasma.

  7. Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations.

    PubMed

    Oishi, Ryu; Tada, Chika; Asano, Ryoki; Yamamoto, Nozomi; Suyama, Yoshihisa; Nakai, Yutaka

    2012-05-01

    A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10 mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10 mM NH (4) (+) -N, whereas AOA grew at 46°C and 10 mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.

  8. Extension of the T{sub z} = {minus}3/2, A = 4n + 1 series of beta-delayed proton emitters to {sup 65}Se and {sup 73}Sr, and low energy beta-delayed proton emission from the T{sub z} = {minus}3/2, A = 4n + 3 nucleus {sup 23}Al

    SciTech Connect

    Batchelder, J.C.

    1993-12-01

    The series of known Tz = {minus}3/2, A = 4n + 1 nuclei has been extended to include the previously undiscovered isotopes {sup 65}Se and {sup 73}Sr, through the observation of beta-delayed proton emission via the isobaric analog state (IAS) of the beta-daughter (emitter). Due to the relatively large proton energies involved, these experiments were conducted using standard Si-Si {Delta}E-E telescopes. Beta-delayed protons arising from {sup 65}Se have been observed at an energy (laboratory) of 3.55 {plus_minus} 0.03 MeV, corresponding to the decay of the T = 3/2 isobaric analog state in {sup 65}As to the ground state of {sup 64}Ge. Similarly, beta-delayed protons from {sup 73}Sr at an energy of 3.75 {plus_minus} 0.04 MeV have been observed, corresponding to decay of the T = 3/2 isobaric analog state in {sup 73}Rb to the ground state of {sup 72}Kr. From the energies of these proton transitions, an improved prediction of the mass excesses of the two parent nuclei ({sup 65}Se and {sup 73}Sr) is made through the use of a Coulomb displacement formula. These predictions are {minus}33.41 {plus_minus} 0.26 and {minus}31.87 {plus_minus} 0.24 MeV for {sup 65}Se and {sup 73}Sr, respectively. Studies of low energy (down to {approximately}200 keV) beta-delayed protons from {sup 23}Al necessitated that a particle identification telescope with a low energy threshold for observation and identification of protons be developed. {sup 23}Al is of interest because of its role in the breakout of the hot CNO cycle leading to the astrophysical rp process.

  9. The Significance of Myriophyllum elatinoides for Swine Wastewater Treatment: Abundance and Community Structure of Ammonia-Oxidizing Microorganisms in Sediments

    PubMed Central

    Li, Xi; Zhang, Miaomiao; Liu, Feng; Li, Yong; He, Yang; Zhang, Shunan; Wu, Jinshui

    2015-01-01

    Myriophyllum elatinoides was reported to effectively treat wastewater by removing nitrogen (N) and phosphorus (P). However, little is known about the abundance and community structure of ammonia-oxidizing microorganisms associated with M. elatinoides purification systems. The objective of this research was to characterize the abundance and community structure of ammonia-oxidizing microorganisms in swine wastewater and determine the main nitrogen removal pathways. In this study, five different waters were treated by M. elatinoides in microcosms for one month. The five waters included tap water (Control), swine wastewater (SW), 50% diluted swine wastewater (50% SW), and two synthetic wastewaters: 200 mg NH4+-N L−1 (200 NH4+-N) and 400 mg NH4+-N L−1 (400 NH4+-N). The most dramatic changes were in NH4+-N and total N (TN) concentrations, with average removal rates of 84% and 90%, respectively, in the treatments containing swine wastewater. On days 7, 14, and 28, the dissolved oxygen (DO) increased by 81.8%, 210.4% and 136.5%, respectively, compared with on day 0, in the swine wastewater. The results also showed that the bacterial amoA (AOB) copy numbers in the sediments of the treatments were significantly higher than those of archaeal amoA (AOA) copy numbers (p = 0.015). In addition, the high DO concentrations in swine wastewater responded well to the high abundance of AOB. The AOA and AOB community distributions were positively related with NO3-N and were negatively related with DO in swine wastewater treatments. In summary, our experimental results suggested that the M. elatinoides purification system could improve the activity of ammonia-oxidizing microorganisms and consequently might contribute to the significant N removal from the swine wastewater. PMID:26444015

  10. Differences in carbon density and soil CH4/N2O flux among remnant and agro-ecosystems established since European settlement in the Mornington Peninsula, Australia.

    PubMed

    Livesley, Stephen J; Idczak, Daniel; Fest, Benedikt J

    2013-11-01

    National and regional C emissions from historical land use change (LUC) and fossil fuel use are proposed as a basis to ascribe 'burden-sharing' for global emission reduction targets. Changes in non-CO2 greenhouse gas emissions as a result of LUC have not been considered, but may be considerable. We measured soil-atmosphere exchange of methane (CH4) and nitrous oxide (N2O) in remnant forest, pasture and viticulture systems in four seasons, as well as differences in soil C density and the C density of remnant forest vegetation. This approach enabled comparative assessment of likely changes in ecosystem C density and soil non-CO2 greenhouse gas exchange along a LUC continuum since European settlement. Soil CH4 uptake was moderate in forest soil (-27 μg C m(-2) h(-1)), and significantly different to occasionally large CH4 emissions from viticulture and pasture soils. Soil N2O emissions were small and did not significantly differ. Soil C density increased significantly with conversion from forest (5 kg m(-2)) to pasture (9 kg m(-2)), and remained high in viticulture. However, there was a net decrease in ecosystem C density with forest conversion to pasture. Concurrently, net soil non-CO2 emissions (CH4 and N2O combined) increased with conversion from forest to pasture. Since European settlement 170 years ago, it was estimated ~8114 Gg CO2-e has been released from changes in ecosystem C density in the Mornington Peninsula, whereas ~383 Gg CO2-e may have been released from changes in soil non-CO2 exchange processes. Principally, a switch from soil CH4 uptake to soil CH4 emission after forest clearing to agro-pastoral systems provided this further ~5% contribution to the historical landscape CO2-e source strength. Conserving and restoring remnant forests and establishing new tree-based systems will enhance landscape C density. Similarly, minimising anaerobic, wet conditions in pasture/viticulture soils will help reduce non-CO2 greenhouse gas emissions.

  11. Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget

    NASA Astrophysics Data System (ADS)

    Teodoru, C. R.; Nyoni, F. C.; Borges, A. V.; Darchambeau, F.; Nyambe, I.; Bouillon, S.

    2015-04-01

    Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. We present data on greenhouse gas (GHG: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) concentrations and fluxes, as well as data that allow for characterization of sources and dynamics of carbon pools collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHG concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O). Overall, there was no unidirectional pattern along the river stretch (i.e., decrease or increase towards the ocean), as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands as well as the presence of man-made structures (reservoirs) and natural barriers (waterfalls, rapids). Highest CO2 and CH4 concentrations in the main channel were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic of the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of the floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River, whereas low values were characteristic of more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to 2-fold) were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced, but higher values

  12. Spatial variability and temporal dynamics of greenhouse gas (CO2, CH4, N2O) concentrations and fluxes along the Zambezi River mainstem and major tributaries

    NASA Astrophysics Data System (ADS)

    Teodoru, C. R.; Nyoni, F. C.; Borges, A. V.; Darchambeau, F.; Nyambe, I.; Bouillon, S.

    2014-11-01

    Spanning over 3000 km in length and with a catchment of approximately 1.4 million km2, the Zambezi River is the fourth largest river in Africa and the largest flowing into the Indian Ocean from the African continent. As part of a~broader study on the riverine biogeochemistry in the Zambezi River basin, we present data on greenhouse gas (GHG, carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O)) concentrations and fluxes collected along the Zambezi River, reservoirs and several of its tributaries during 2012 and 2013 and over two climatic seasons (dry and wet) to constrain the interannual variability, seasonality and spatial heterogeneity along the aquatic continuum. All GHGs concentrations showed high spatial variability (coefficient of variation: 1.01 for CO2, 2.65 for CH4 and 0.21 for N2O). Overall, there was no unidirectional pattern along the river stretch (i.e. decrease or increase towards the ocean), as the spatial heterogeneity of GHGs appeared to be determined mainly by the connectivity with floodplains and wetlands, and the presence of man-made structures (reservoirs) and natural barriers (waterfalls, rapids). Highest CO2 and CH4 concentrations in the mainstream river were found downstream of extensive floodplains/wetlands. Undersaturated CO2 conditions, in contrast, were characteristic for the surface waters of the two large reservoirs along the Zambezi mainstem. N2O concentrations showed the opposite pattern, being lowest downstream of floodplains and highest in reservoirs. Among tributaries, highest concentrations of both CO2 and CH4 were measured in the Shire River whereas low values were characteristic for more turbid systems such as the Luangwa and Mazoe rivers. The interannual variability in the Zambezi River was relatively large for both CO2 and CH4, and significantly higher concentrations (up to two fold) were measured during wet seasons compared to the dry season. Interannual variability of N2O was less pronounced but generally higher

  13. NOpiates: Novel Dual Action Neuronal Nitric Oxide Synthase Inhibitors with μ-Opioid Agonist Activity

    PubMed Central

    2012-01-01

    A novel series of benzimidazole designed multiple ligands (DMLs) with activity at the neuronal nitric oxide synthase (nNOS) enzyme and the μ-opioid receptor was developed. Targeting of the structurally dissimilar heme-containing enzyme and the μ-opioid GPCR was predicated on the modulatory role of nitric oxide on μ-opioid receptor function. Structure–activity relationship studies yielded lead compound 24 with excellent nNOS inhibitory activity (IC50 = 0.44 μM), selectivity over both endothelial nitric oxide synthase (10-fold) and inducible nitric oxide synthase (125-fold), and potent μ-opioid binding affinity, Ki = 5.4 nM. The functional activity as measured in the cyclic adenosine monosphospate secondary messenger assay resulted in full agonist activity (EC50 = 0.34 μM). This work represents a novel approach in the development of new analgesics for the treatment of pain. PMID:24900459

  14. Enhanced tunnelling electroresistance effect due to a ferroelectrically induced phase transition at a magnetic complex oxide interface.

    PubMed

    Yin, Y W; Burton, J D; Kim, Y-M; Borisevich, A Y; Pennycook, S J; Yang, S M; Noh, T W; Gruverman, A; Li, X G; Tsymbal, E Y; Li, Qi

    2013-05-01

    The range of recently discovered phenomena in complex oxide heterostructures, made possible owing to advances in fabrication techniques, promise new functionalities and device concepts. One issue that has received attention is the bistable electrical modulation of conductivity in ferroelectric tunnel junctions (FTJs) in response to a ferroelectric polarization of the tunnelling barrier, a phenomenon known as the tunnelling electroresistance (TER) effect. Ferroelectric tunnel junctions with ferromagnetic electrodes allow ferroelectric control of the tunnelling spin polarization through the magnetoelectric coupling at the ferromagnet/ferroelectric interface. Here we demonstrate a significant enhancement of TER due to a ferroelectrically induced phase transition at a magnetic complex oxide interface. Ferroelectric tunnel junctions consisting of BaTiO3 tunnelling barriers and La(0.7)Sr(0.3)MnO3 electrodes exhibit a TER enhanced by up to ~10,000% by a nanometre-thick La(0.5)Ca(0.5)MnO3 interlayer inserted at one of the interfaces. The observed phenomenon originates from the metal-to-insulator phase transition in La(0.5)Ca(0.5)MnO3, driven by the modulation of carrier density through ferroelectric polarization switching. Electrical, ferroelectric and magnetoresistive measurements combined with first-principles calculations provide evidence for a magnetoelectric origin of the enhanced TER, and indicate the presence of defect-mediated conduction in the FTJs. The effect is robust and may serve as a viable route for electronic and spintronic applications. PMID:23416728

  15. Vascular oxidative stress, nitric oxide and atherosclerosis.

    PubMed

    Li, Huige; Horke, Sven; Förstermann, Ulrich

    2014-11-01

    In the vascular wall, reactive oxygen species (ROS) are produced by several enzyme systems including NADPH oxidase, xanthine oxidase, uncoupled endothelial nitric oxide synthase (eNOS) and the mitochondrial electron transport chain. On the other hand, the vasculature is protected by antioxidant enzyme systems, including superoxide dismutases, catalase, glutathione peroxidases and paraoxonases, which detoxify ROS. Cardiovascular risk factors such as hypercholesterolemia, hypertension, and diabetes mellitus enhance ROS generation, resulting in oxidative stress. This leads to oxidative modification of lipoproteins and phospholipids, mechanisms that contribute to atherogenesis. In addition, oxidation of tetrahydrobiopterin may cause eNOS uncoupling and thus potentiation of oxidative stress and reduction of eNOS-derived NO, which is a protective principle in the vasculature. This review summarizes the latest advances in the role of ROS-producing enzymes, antioxidative enzymes as well as NO synthases in the initiation and development of atherosclerosis.

  16. The electrochemiluminescence of luminol on titania nanotubes functionalised indium tin oxide glass for flow injection analysis.

    PubMed

    Zhao, Qun; Xiao, Changbin; Tu, Yifeng

    2015-10-01

    The titania nanotubes (TiNTs) had been immobilised onto the indium tin oxide (ITO) coated glass to intensify the electrochemiluminescence (ECL) of luminol. The morphology, structure and properties such as specific surface area and transmittance of synthesised TiNTs were characterised. The results indicated that the TiNTs was several hundred nanometres in length with the diameter of 20 nm. In flow injection analysis (FIA) mode, the TiNTs dramatically enhanced the ECL emission of luminol for about 25 multiple, meanwhile decreased the requirement of buffer pH and exciting potential. The ECL emission of luminol on functionalised ITO electrode has sensitive response toward hydrogen peroxide, and extraordinarily responsive toward the antioxidant. Under the optimal conditions, the ECL emission exhibited a linear response within the concentration range from 0.1 mg L(-1) to 30 mg L(-1) and an absolute detection limit of 1.65×10(-10) g of resveratrol. The gross antioxidant activity of blueberry and kiwi were determined with satisfactory recoveries.

  17. LETTER TO THE EDITOR: A potential oxide for magnetic refrigeration application: CrO2 particles

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyu; Chen, Yajie; Lü, Liya; Li, Zhenya

    2006-11-01

    The magnetocaloric effect (MCE) of half-metallic CrO2 particles has been studied with respect to particle size on the nanometre scale. Results from superconducting quantum interference device (SQUID) measurements indicate that acicular CrO2 particles with a length of 400 nm yield a large magnetic entropy change ΔSM of 5.1 J kg-1 K-1 at an applied field of 15 kOe and an adiabatic temperature change ΔTad of 2.0 K near the Curie temperature (~390 K). These results are among the highest for magnetic oxides, and are comparable to that for pure Gd. However, smaller CrO2 particles with a length of 260 nm only exhibit ΔSM = 2.25 J kg-1 K-1 and ΔTad = 0.95 K. The difference in MCE between these two sizes of CrO2 particles results primarily from disordered spins on the surface of the particles. In addition, measurements and calculations of the specific heat capacity for the CrO2 particles are presented. These results indicate that the total specific heat capacity is dominated by the magnetic specific heat contribution. Therefore, we believe that these CrO2 nanoparticles may hold future promise in the development of new magnetic refrigerants.

  18. High-temperature interface superconductivity between metallic and insulating copper oxides.

    PubMed

    Gozar, A; Logvenov, G; Kourkoutis, L Fitting; Bollinger, A T; Giannuzzi, L A; Muller, D A; Bozovic, I

    2008-10-01

    The realization of high-transition-temperature (high-T(c)) superconductivity confined to nanometre-sized interfaces has been a long-standing goal because of potential applications and the opportunity to study quantum phenomena in reduced dimensions. This has been, however, a challenging target: in conventional metals, the high electron density restricts interface effects (such as carrier depletion or accumulation) to a region much narrower than the coherence length, which is the scale necessary for superconductivity to occur. By contrast, in copper oxides the carrier density is low whereas T(c) is high and the coherence length very short, which provides an opportunity-but at a price: the interface must be atomically perfect. Here we report superconductivity in bilayers consisting of an insulator (La(2)CuO(4)) and a metal (La(1.55)Sr(0.45)CuO(4)), neither of which is superconducting in isolation. In these bilayers, T(c) is either approximately 15 K or approximately 30 K, depending on the layering sequence. This highly robust phenomenon is confined within 2-3 nm of the interface. If such a bilayer is exposed to ozone, T(c) exceeds 50 K, and this enhanced superconductivity is also shown to originate from an interface layer about 1-2 unit cells thick. Enhancement of T(c) in bilayer systems was observed previously but the essential role of the interface was not recognized at the time. PMID:18843365

  19. Nucleation and growth of intragranular defect and insoluble atom clusters in nuclear oxide fuels

    NASA Astrophysics Data System (ADS)

    Garcia, P.; Martin, G.; Sabathier, C.; Carlot, G.; Michel, A.; Martin, P.; Dorado, B.; Freyss, M.; Bertolus, M.; Skorek, R.; Noirot, J.; Noirot, L.; Kaitasov, O.; Maillard, S.

    2012-04-01

    Uranium and plutonium oxides are subjected to high levels of radiation damage due to the slowing of fission fragments. In addition the composition of the material evolves over time as a result of fission events. Rare gases which constitute an abundant class of fission products are particularly insoluble and therefore tend either to be released from the fuel or form small nanometre size clusters. Bubbles are liable to grow and become trapping sites for migrating defects or other insoluble atoms. Interactions between migrating atoms, defects and existing clusters will determine the rate and extent to which clusters grow. Because the transfer of gas from within the grain to the grain boundaries is thought of as being the rate limiting process for fission gas release, a review of phenomena occurring on the sub-grain scale is carried out. The microstructural modifications induced by neutron irradiations of UO2 fuels are discussed with an emphasis on their relation to fission gas release. Based mainly on TEM studies, the phenomena which are usually taken into account in fission gas behaviour models are looked at and the limitations of these models outlined. More recent experimental and modelling approaches involving ion-irradiation experiments and atomic scale modelling are presented. It is shown that combining these approaches may lead, despite the complexity inherent to the system, to a better understanding of basic radiation induced microstructural changes, clustering events, and rare gas behaviour.

  20. High-temperature interface superconductivity between metallic and insulating copper oxides.

    PubMed

    Gozar, A; Logvenov, G; Kourkoutis, L Fitting; Bollinger, A T; Giannuzzi, L A; Muller, D A; Bozovic, I

    2008-10-01

    The realization of high-transition-temperature (high-T(c)) superconductivity confined to nanometre-sized interfaces has been a long-standing goal because of potential applications and the opportunity to study quantum phenomena in reduced dimensions. This has been, however, a challenging target: in conventional metals, the high electron density restricts interface effects (such as carrier depletion or accumulation) to a region much narrower than the coherence length, which is the scale necessary for superconductivity to occur. By contrast, in copper oxides the carrier density is low whereas T(c) is high and the coherence length very short, which provides an opportunity-but at a price: the interface must be atomically perfect. Here we report superconductivity in bilayers consisting of an insulator (La(2)CuO(4)) and a metal (La(1.55)Sr(0.45)CuO(4)), neither of which is superconducting in isolation. In these bilayers, T(c) is either approximately 15 K or approximately 30 K, depending on the layering sequence. This highly robust phenomenon is confined within 2-3 nm of the interface. If such a bilayer is exposed to ozone, T(c) exceeds 50 K, and this enhanced superconductivity is also shown to originate from an interface layer about 1-2 unit cells thick. Enhancement of T(c) in bilayer systems was observed previously but the essential role of the interface was not recognized at the time.

  1. Electrolytic oxidation of anthracite

    USGS Publications Warehouse

    Senftle, F.E.; Patton, K.M.; Heard, I.

    1981-01-01

    An anthracite slurry can be oxidized only with difficulty by electrolytic methods in which aqueous electrolytes are used if the slurry is confined to the region of the anode by a porous pot or diaphragm. However, it can be easily oxidized if the anthracite itself is used as the anode. No porous pot or diaphragm is needed. Oxidative consumption of the coal to alkali-soluble compounds is found to proceed preferentially at the edges of the aromatic planes. An oxidation model is proposed in which the chief oxidants are molecular and radical species formed by the electrolytic decomposition of water at the coal surface-electrolyte interface. The oxidation reactions proposed account for the opening of the aromatic rings and the subsequent formation of carboxylic acids. The model also explains the observed anisotropic oxidation and the need for the porous pot or diaphragm used in previous studies of the oxidation of coal slurries. ?? 1981.

  2. Zinc oxide overdose

    MedlinePlus

    Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used ... prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of ...

  3. Bridged graphite oxide materials

    NASA Technical Reports Server (NTRS)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  4. Mixed Acid Oxidation

    SciTech Connect

    Pierce, R.A.

    1999-10-26

    Several non-thermal processes have been developed to destroy organic waste compounds using chemicals with high oxidation potentials. These efforts have focused on developing technologies that work at low temperatures, relative to incineration, to overcome many of the regulatory issues associated with obtaining permits for waste incinerators. One such technique with great flexibility is mixed acid oxidation. Mixed acid oxidation, developed at the Savannah River Site, uses a mixture of an oxidant (nitric acid) and a carrier acid (phosphoric acid). The carrier acid acts as a non-volatile holding medium for the somewhat volatile oxidant. The combination of acids allows appreciable amounts of the concentrated oxidant to remain in the carrier acid well above the oxidant''s normal boiling point.

  5. Studies in zirconium oxidation

    NASA Technical Reports Server (NTRS)

    Draley, J. E.; Drunen, C. J.; Levitan, J.

    1968-01-01

    Study provides insight into the oxidation mechanism of zirconium by combining electrical measurements with oxidation data. The measurement of electrical potential across growing scale on zirconium and the determination of conventional weight-change oxidation data were carried out at 550, 700, and 800 degrees C.

  6. Congruently melting complex oxides

    SciTech Connect

    Abrahams, S.C.; Brandle, C.D. Jr.

    1988-04-26

    A device is described comprising: a material including a complex oxide, characterized in that the complex oxide is essentially free of gadolinium scandium gallium garnet, gadolinium gallium garnet and lithium niobate, and the composition of the complex oxide is congruent and differs from stoichiometry by at least 0.1 atomic percent for at least one constituent element.

  7. Diversity and distribution of planktonic anaerobic ammonium-oxidizing bacteria in the Dongjiang River, China.

    PubMed

    Sun, Wei; Xia, Chunyu; Xu, Meiying; Guo, Jun; Wang, Aijie; Sun, Guoping

    2014-12-01

    Anaerobic ammonium-oxidizing (anammox) process has recently been recognized as an important pathway for removing fixed nitrogen (N) from aquatic ecosystems. Anammox organisms are widely distributed in freshwater environments. However, little is known about their presence in the water column of riverine ecosystems. Here, the existence of a diverse anammox community was revealed in the water column of the Dongjiang River by analyzing 16S rRNA and hydrazine oxidation (hzo) genes of anammox bacteria. Phylogenetic analyses of hzo genes showed that Candidatus Jettenia related clades of anammox bacteria were dominant in the river, suggesting the ecological microniche distinction from freshwater/estuary and marine anammox bacteria with Ca. Brocadia and Kuenenia genera mainly detected in freshwater/estuary ecosystems, and Ca. Scalindua genus mainly detected in marine ecosystems. The abundance and diversity of anammox bacteria along the river were both significantly correlated with concentrations of NH4(+)-N based on Pearson and partial correlation analyses. Redundancy analyses showed the contents of NH4(+)-N, NO3(-)-N and the ratio of NH4(+)-N to NO2(-)-N significantly influenced the spatial distributions of anammox bacteria in the water column of the Dongjiang River. These results expanded our understanding of the distribution and potential roles of anammox bacteria in the water column of the river ecosystem.

  8. Iron oxide superparamagnetic nanoparticles conjugated with a conformationally blocked α-Tn antigen mimetic for macrophage activation

    NASA Astrophysics Data System (ADS)

    Manuelli, Massimo; Fallarini, Silvia; Lombardi, Grazia; Sangregorio, Claudio; Nativi, Cristina; Richichi, Barbara

    2014-06-01

    Among new therapies to fight tumors, immunotherapy is still one of the most promising and intriguing. Thanks to the ongoing structural elucidation of several tumor antigens and the development of innovative antigen carriers, immunotherapy is in constant evolution and it is largely used either alone or in synergy with chemotherapy/radiotherapy. With the aim to develop fully synthetic immunostimulants we have recently developed a mimetic of the α-Tn mucin antigen, a relevant tumor antigen. The 4C1 blocked mimetic 1, unique example of an α-Tn mimetic antigen, was functionalized with an ω-phosphonate linker and used to decorate iron oxide superparamagnetic nanoparticles (MNPs), employed as multivalent carriers. MNPs, largely exploited for supporting and carrying biomolecules, like antibodies, drugs or antigens, consent to combine in the same nanometric system the main features of an inorganic magnetic core with a bioactive organic coating. The superparamagnetic glyconanoparticles obtained, named GMNPs, are indeed biocompatible and immunoactive, and they preserve suitable characteristics for use as heat mediators in the magnetic fluid hyperthermia (MFH) treatment of tumors. All together these properties make GMNPs attracting devices for innovative tumor treatment.Among new therapies to fight tumors, immunotherapy is still one of the most promising and intriguing. Thanks to the ongoing structural elucidation of several tumor antigens and the development of innovative antigen carriers, immunotherapy is in constant evolution and it is largely used either alone or in synergy with chemotherapy/radiotherapy. With the aim to develop fully synthetic immunostimulants we have recently developed a mimetic of the α-Tn mucin antigen, a relevant tumor antigen. The 4C1 blocked mimetic 1, unique example of an α-Tn mimetic antigen, was functionalized with an ω-phosphonate linker and used to decorate iron oxide superparamagnetic nanoparticles (MNPs), employed as multivalent

  9. Rhodium oxides in unusual oxidation states

    NASA Astrophysics Data System (ADS)

    Reisner, Barbara Alice

    Mixed valence RhIII/RhIV oxides have been proposed as a promising class of candidate compounds for superconductivity. Unfortunately, it is difficult to stabilize rhodates with a formal oxidation state approaching RhIV, as other techniques used for the synthesis of rhodium. oxides favor the most commonly observed formal oxidation state, RhIII. One technique which has been used to stabilize metal oxides in high formal oxidation states is crystallization from molten hydroxides. This thesis explores the use of molten hydroxides to enhance the reactivity of rhodium oxides in order to synthesize rhodates with high formal oxidation states. K0.5RhO2, Rb0.2RhO2, and CsxRhO2 were synthesized from pure alkali metal hydroxides. All crystallized with a previously unobserved polytype in the alkali metal rhodate system. Due to the low activity of dissolved oxygen species in LiOH and NaOH, LiRhO2 and NaRhO2 cannot be crystallized. The formal oxidation state of rhodium in AxRhO2 (A = K, Rb, Cs) is a function of the alkali metal hydroxide used to synthesize these oxides. These materials exhibit remarkable stability for layered metal oxides containing the heavier alkali metals, but all phases are susceptible to intercalation by water. The synthesis, structural characterization, magnetic susceptibility, and reactivity of these oxides are reported. Sr2RhO4 and a new rhodate were crystallized from a KOH-Sr(OH)2 flux. The synthesis and characterization of these materials is reported. Efforts to substitute platinum for rhodium in Sr 2RhO4 are also discussed. Mixed alkali metal-alkaline earth metal hydroxide fluxes were used to crystallize LiSr3RhO6, and NaSr3RhO 6. The synthesis of LiSr3RhO6 and NaSr3RhO 6 represents the first example of the stabilization of a rhodium oxide with a formal oxidation state approaching RhV. X-ray diffraction, electron beam microprobe analysis, thermogravimetric analysis, potentiometric titrations, X-ray photoelectron spectroscopy, and magnetic susceptibility

  10. In Situ Coupling of Strung Co4N and Intertwined N-C Fibers toward Free-Standing Bifunctional Cathode for Robust, Efficient, and Flexible Zn-Air Batteries.

    PubMed

    Meng, Fanlu; Zhong, Haixia; Bao, Di; Yan, Junmin; Zhang, Xinbo

    2016-08-17

    Flexible power sources with high energy density are crucial for the realization of next-generation flexible electronics. Theoretically, rechargeable flexible zinc-air (Zn-air) batteries could provide high specific energy, while their large-scale applications are still greatly hindered by high cost and resources scarcity of noble-metal-based oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) electrocatalysts as well as inferior mechanical properties of the air cathode. Combining metallic Co4N with superior OER activity and Co-N-C with perfect ORR activity on a free-standing and flexible electrode could be a good step for flexible Zn-air batteries, while lots of difficulties need to be overcome. Herein, as a proof-of-concept experiment, we first propose a strategy for in situ coupling of strung Co4N and intertwined N-C fibers, by pyrolyzation of the novel pearl-like ZIF-67/polypyrrole nanofibers network rooted on carbon cloth. Originating from the synergistic effect of Co4N and Co-N-C and the stable 3D interconnected conductive network structure, the obtained free-standing and highly flexible bifunctional oxygen electrode exhibits excellent electrocatalytic activity and stability for both OER and ORR in terms of low overpotential (310 mV at 10 mA cm(-2)) for OER, a positive half-wave potential (0.8 V) for ORR, and a stable current density retention for at least 20 h, and especially, the obtained Zn-air batteries exhibit a low discharge-charge voltage gap (1.09 V at 50 mA cm(-2)) and long cycle life (up to 408 cycles). Furthermore, the perfect bendable and twistable and rechargeable properties of the flexible Zn-air battery particularly make it a potentially power portable and wearable electronic device.

  11. Sunscreens and T4N5 liposomes differ in their ability to protect against ultraviolet-induced sunburn cell formation, alterations of dendritic epidermal cells, and local suppression of contact hypersensitivity.

    PubMed

    Wolf, P; Cox, P; Yarosh, D B; Kripke, M L

    1995-02-01

    Exposure of skin to ultraviolet (UV) radiation can lead to diverse biologic effects, including inflammation, sunburn cell formation, alterations of cutaneous immune cells, and impaired induction of contact hypersensitivity responses. The molecular mechanisms of these UV-induced effects are not completely understood. We investigated the ability of sunscreens and liposomes containing the DNA excision repair enzyme T4 endonuclease V to prevent these effects of UV radiation. The use of T4N5 liposomes, which increase the repair of cyclobutyl pyrimidine dimers, provides an approach for assessing the role of DNA damage in the effects of UV radiation on the skin. Exposing C3H mice to 500 mJ/cm2 UVB radiation from FS40 sunlamps resulted in skin edema, sunburn cell formation, and morphologic alterations and decreased numbers of Langerhans cells and Thy-1+ dendritic epidermal T cells. In addition, the induction of contact hypersensitivity after application of 2,4-dinitrofluorobenzene on UV-irradiated skin was diminished by 80%. Applying sunscreens containing octyl-N-dimethyl-p-aminobenzoate, 2-ethylhexyl-p-methoxycinnamate, or benzophenone-3 before this dose of UV irradiation gave nearly complete protection against all of these effects of UV irradiation. In contrast, topical application of T4N5 liposomes after UV irradiation had no effect on UV-induced skin edema and only partially protected against sunburn cell formation and local suppression of contact hypersensitivity, although its ability to protect against alterations in dendritic immune cells was comparable to that of the sunscreens. These results suggest that DNA damage is involved in only some of the local effects of UV radiation on the skin. In addition, T4N5 liposomes may be a useful adjunct to sunscreens because they can reduce some of the deleterious effects of UV radiation on skin even after a sunburn has been initiated. PMID:7829886

  12. Synthesis and Mechanical Wear Studies of Ultra Smooth Nanostructured Diamond (USND) Coatings Deposited by Microwave Plasma Chemical Vapor Deposition with He/H2/CH4/N2 Mixtures

    PubMed Central

    Chowdhury, S.; Borham, J.; Catledge, S. A.; Eberhardt, A. W.; Johnson, P. S.; Vohra, Y. K.

    2008-01-01

    Ultra smooth nanostructured diamond (USND) coatings were deposited by microwave plasma chemical vapor deposition (MPCVD) technique using He/H2/CH4/N2 gas mixture. The RMS surface roughness as low as 4 nm (2 micron square area) and grain size of 5–6 nm diamond coatings were achieved on medical grade titanium alloy. Previously it was demonstrated that the C2 species in the plasma is responsible for the production of nanocrystalline diamond coatings in the Ar/H2/CH4 gas mixture. In this work we have found that CN species is responsible for the production of USND coatings in He/H2/CH4/N2 plasma. It was found that diamond coatings deposited with higher CN species concentration (normalized by Balmer Hα line) in the plasma produced smoother and highly nanostructured diamond coatings. The correlation between CN/Hα ratios with the coating roughness and grain size were also confirmed with different set of gas flows/plasma parameters. It is suggested that the presence of CN species could be responsible for producing nanocrystallinity in the growth of USND coatings using He/H2/CH4/N2 gas mixture. The RMS roughness of 4 nm and grain size of 5–6 nm were calculated from the deposited diamond coatings using the gas mixture which produced the highest CN/Hα species in the plasma. Wear tests were performed on the OrthoPOD®, a six station pin-on-disk apparatus with ultra-high molecular weight polyethylene (UHMWPE) pins articulating on USND disks and CoCrMo alloy disk. Wear of the UHMWPE was found to be lower for the polyethylene on USND than that of polyethylene on CoCrMo alloy. PMID:19112519

  13. In Situ Coupling of Strung Co4N and Intertwined N-C Fibers toward Free-Standing Bifunctional Cathode for Robust, Efficient, and Flexible Zn-Air Batteries.

    PubMed

    Meng, Fanlu; Zhong, Haixia; Bao, Di; Yan, Junmin; Zhang, Xinbo

    2016-08-17

    Flexible power sources with high energy density are crucial for the realization of next-generation flexible electronics. Theoretically, rechargeable flexible zinc-air (Zn-air) batteries could provide high specific energy, while their large-scale applications are still greatly hindered by high cost and resources scarcity of noble-metal-based oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) electrocatalysts as well as inferior mechanical properties of the air cathode. Combining metallic Co4N with superior OER activity and Co-N-C with perfect ORR activity on a free-standing and flexible electrode could be a good step for flexible Zn-air batteries, while lots of difficulties need to be overcome. Herein, as a proof-of-concept experiment, we first propose a strategy for in situ coupling of strung Co4N and intertwined N-C fibers, by pyrolyzation of the novel pearl-like ZIF-67/polypyrrole nanofibers network rooted on carbon cloth. Originating from the synergistic effect of Co4N and Co-N-C and the stable 3D interconnected conductive network structure, the obtained free-standing and highly flexible bifunctional oxygen electrode exhibits excellent electrocatalytic activity and stability for both OER and ORR in terms of low overpotential (310 mV at 10 mA cm(-2)) for OER, a positive half-wave potential (0.8 V) for ORR, and a stable current density retention for at least 20 h, and especially, the obtained Zn-air batteries exhibit a low discharge-charge voltage gap (1.09 V at 50 mA cm(-2)) and long cycle life (up to 408 cycles). Furthermore, the perfect bendable and twistable and rechargeable properties of the flexible Zn-air battery particularly make it a potentially power portable and wearable electronic device. PMID:27463122

  14. Assembly of polymeric silver(I) complexes of isomeric phenylenediethynides with the supramolecular synthons Agn subset C2-R-C2 superset Agn (R = p-, m-, o-C6H4; n = 4, 5).

    PubMed

    Zhao, Liang; Mak, Thomas C W

    2005-11-01

    New Agn subset C2-R-C2 supersetAgn (R = p-, m-, o-C6H4; n = 4, 5) supramolecular synthons have been explored in the coordination network assembly of silver(I) complexes of the isomeric phenylenediethynides. An unprecedented mu5-eta1-coordination mode for the ethynide moiety and a mixed mu4,mu5-coordination mode for the o-phenylenediethynide group are observed, providing a rationale for the abundant occurrence of C2@Agn (n

  15. Solid-State Chemistry as a Formation Mechanism for C 4N 2 Ice and Possibly the Haystack (220 cm -1 ice emission feature) in Titan's Stratosphere as Observed by Cassini CIRS

    NASA Astrophysics Data System (ADS)

    Anderson, Carrie; Samuelson, Robert E.; McLain, Jason L.; Nna Mvondo, Delphine; Romani, Paul; Flasar, F. Michael

    2016-10-01

    A profusion of organic ices containing hydrocarbons, nitriles, and combinations of their mixtures comprise Titan's complex stratospheric cloud systems, and are typically formed via vapor condensation. These ice particles are then distributed throughout the mid-to-lower stratosphere, with an increased abundance near the winter poles (see Anderson et al., 2016). The cold temperatures and the associated strong circumpolar winds that isolate polar air act in much the same way as on Earth, giving rise to compositional anomalies and stratospheric clouds that provide heterogeneous chemistry sites.Titan's C4N2 ice emission feature at 478 cm-1 and "the Haystack," a strong unidentified stratospheric ice emission feature centered at 220 cm-1, share a common characteristic. Even though both are distinctive ice emission features evident in Cassini Composite InfraRed (CIRS) far-IR spectra, no associated vapor emission features can be found in Titan's atmosphere. Without a vapor phase, solid-state chemistry provides an alternate mechanism beside vapor condensation for producing these observed stratospheric ices.Anderson et al., (2016) postulated that C4N2 ice formed in Titan's stratosphere via the solid-state photochemical reaction HCN + HC3N → C4N2 + H2 can occur within extant HCN-HC3N composite ice particles. Such a reaction, and potentially similar reactions that may produce the Haystack ice, are specific examples of solid-state chemistry in solar system atmospheres. This is in addition to the reaction HCl + ClONO2 → HNO3 + Cl2, which is known to produce HNO3 coatings on terrestrial water ice particles, a byproduct of the catalytic chlorine chemistry that produces ozone holes in Earth's polar stratosphere (see for example, Molina et al., 1987 Soloman, 1999).A combination of radiative transfer modeling of CIRS far-IR spectra, coupled with optical constants derived from thin film transmittance spectra of organic ice mixtures obtained in our Spectroscopy for Planetary ICes

  16. All-Oxide Photovoltaics.

    PubMed

    Rühle, Sven; Anderson, Assaf Y; Barad, Hannah-Noa; Kupfer, Benjamin; Bouhadana, Yaniv; Rosh-Hodesh, Eli; Zaban, Arie

    2012-12-20

    Recently, a new field in photovoltaics (PV) has emerged, focusing on solar cells that are entirely based on metal oxide semiconductors. The all-oxide PV approach is very attractive due to the chemical stability, nontoxicity, and abundance of many metal oxides that potentially allow manufacturing under ambient conditions. Already today, metal oxides (MOs) are widely used as components in PV cells such as transparent conducting front electrodes or electron-transport layers, while only very few MOs have been used as light absorbers. In this Perspective, we review recent developments of all-oxide PV systems, which until today were mostly based on Cu2O as an absorber. Furthermore, ferroelectric BiFeO3-based PV systems are discussed, which have recently attracted considerable attention. The performance of all-oxide PV cells is discussed in terms of general PV principles, and directions for progress are proposed, pointing toward the development of novel metal oxide semiconductors using combinatorial methods.

  17. Partial oxidation catalyst

    DOEpatents

    Krumpelt, Michael; Ahmed, Shabbir; Kumar, Romesh; Doshi, Rajiv

    2000-01-01

    A two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion. The dehydrogenation portion is a group VIII metal and the oxide-ion conducting portion is selected from a ceramic oxide crystallizing in the fluorite or perovskite structure. There is also disclosed a method of forming a hydrogen rich gas from a source of hydrocarbon fuel in which the hydrocarbon fuel contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion at a temperature not less than about 400.degree. C. for a time sufficient to generate the hydrogen rich gas while maintaining CO content less than about 5 volume percent. There is also disclosed a method of forming partially oxidized hydrocarbons from ethanes in which ethane gas contacts a two-part catalyst comprising a dehydrogenation portion and an oxide-ion conducting portion for a time and at a temperature sufficient to form an oxide.

  18. The study of leachate treatment by using three advanced oxidation process based wet air oxidation

    PubMed Central

    2013-01-01

    Wet air oxidation is regarded as appropriate options for wastewater treatment with average organic compounds. The general purpose of this research is to determine the efficiency of three wet air oxidation methods, wet oxidation with hydrogen peroxide and absorption with activated carbon in removing organic matter and nitrogenous compounds from Isfahan's urban leachate. A leachate sample with the volume of 1.5 liters entered into a steel reactor with the volume of three liters and was put under a 10-bar pressure, at temperatures of 100, 200, and 300° as well as three retention times of 30, 60, and 90 minutes. The sample was placed at 18 stages of leachate storage ponds in Isfahan Compost Plant with the volume of 20 liters, using three WPO, WAO methods and a combination of WAO/GAC for leachate pre-treatment. Thirty percent of pure oxygen and hydrogen peroxide were applied as oxidation agents. The COD removal efficiency in WAO method is 7.8-33.3%, in BOD is 14.7-50.6%, the maximum removal percentage (efficiency) for NH4-N is 53.3% and for NO3-N is 56.4-73.9%. The removal efficiency of COD and BOD5 is 4.6%-34 and 24%-50 respectively in WPO method. Adding GAC to the reactor, the removal efficiency of all parameters was improved. The maximum removal efficiency was increased 48% for COD, 31%-43.6 for BOD5 by a combinational method, and the ratio of BOD5/COD was also increased to 90%. In this paper, WAO and WPO process was used for Leachate pre-treatment and WAO/GAC combinational process was applied for improving the organic matter removal and leachate treatment; it was also determined that the recent process is much more efficient in removing resistant organic matter. PMID:23369258

  19. ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION

    SciTech Connect

    Dang, Y. Y.; Bhuiyan, M.S.; Paranthaman, M. P.

    2008-01-01

    Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic fi lms can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide fi lm to fl ake off. Further studies are needed to defi ne the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  20. Zirconium Oxide Nanostructures Prepared by Anodic Oxidation

    SciTech Connect

    Dang, Ying Yi; Bhuiyan, Md S; Paranthaman, Mariappan Parans

    2008-01-01

    Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic films can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide film to flake off. Further studies are needed to define the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  1. Metabolic Signatures of Oxidative Stress and Their Relationship with Erythrocyte Membrane Surface Roughness Among Workers of Manual Materials Handling (MMH)

    PubMed Central

    Ghosh, Subrata; Acharyya, Muktish; Majumder, Titlee; Bagchi, Anandi

    2015-01-01

    Background: Brickfield workers in India perform manual materials handling (MMH) and as a result, are at a high risk of developing oxidative stress. This results in an alteration of the various markers of metabolic oxidative stress at the cellular level. Since red blood cell (RBC) is the central point where oxygen, glucose-6-phosphate dehydrogenase (G-6-PD), and glutathione (GSH) are involved, the surface roughness and its alteration and modeling with respect to workers exposed to MMH may be considered as helpful determinants in predicting early damage to the cell and restoring better health to the exposed population, that is, the worker exposed to stress. Hence, nanometric analysis of the surface roughness of the RBC may serve as an early indicator of the stress-related damage in these individuals. Aims: The purpose of the study was to identify early red blood corpuscular surface damage profile in terms of linear modeling correlating various biochemical parameters. Linear modeling has been aimed to be developed in order to demonstrate how individual oxidative stress markers such as malondialdehyde (MDA), G-6-PD, and reduced GSH are related to the RBC surface roughness [root mean square (RMS)]. Materials and Methods: Conventional analysis of these biochemical responses were evaluated in MMH laborers (age varying between 18 years and 21 years) and a comparable control group of the same age group (with sedentary lifestyles). Peak expiratory flow rate (PEFR) and RBC surface analysis by atomic-force microscopy (AFM) and correlated scanning probe microscopy (SPM-analytical software) with corresponding image analysis were performed immediately after completion of standardized exercise (MMH) at the brickfield. Results: A number of correlated significances and regressive linear models were developed among MDA, G-6-PD, GSH, and RBC surface roughness. Conclusion: It appears that these linear models might be instrumental in predicting early oxidative damages related to

  2. Oxidative Cross-Coupling of Two Different Phenols: An Efficient Route to Unsymmetrical Biphenols.

    PubMed

    More, Nagnath Yadav; Jeganmohan, Masilamani

    2015-06-19

    An efficient synthesis of unsymmetrical biphenols via the oxidative cross-coupling of two different phenols in the presence of K2S2O8 and Bu4N(+)·HSO3(-) (10 mol %) in CF3COOH at ambient conditions is described. 1:1 Cross-coupling of substituted phenols with naphthols and 1:2 cross-coupling of naphthols with phenol are also disclosed. By using Bu4N(+)·HSO3(-), the homocoupling of phenols or naphthols was controlled. In these reactions, the ortho C-H bond of two different phenols and the ortho and para C-H bond of phenols were coupled together. PMID:26023816

  3. Reduction of Metal Oxide to Metal using Ionic Liquids

    SciTech Connect

    Dr. Ramana Reddy

    2012-04-12

    A novel pathway for the high efficiency production of metal from metal oxide means of electrolysis in ionic liquids at low temperature was investigated. The main emphasis was to eliminate the use of carbon and high temperature application in the reduction of metal oxides to metals. The emphasis of this research was to produce metals such as Zn, and Pb that are normally produced by the application of very high temperatures. The reduction of zinc oxide to zinc and lead oxide to lead were investigated. This study involved three steps in accomplishing the final goal of reduction of metal oxide to metal using ionic liquids: 1) Dissolution of metal oxide in an ionic liquid, 2) Determination of reduction potential using cyclic voltammetry (CV) and 3) Reduction of the dissolved metal oxide. Ionic liquids provide additional advantage by offering a wide potential range for the deposition. In each and every step of the process, more than one process variable has been examined. Experimental results for electrochemical extraction of Zn from ZnO and Pb from PbO using eutectic mixtures of Urea ((NH2)2CO) and Choline chloride (HOC2H4N(CH3)3+Cl-) or (ChCl) in a molar ratio 2:1, varying voltage and temperatures were carried out. Fourier Transform Infra-Red (FTIR) spectroscopy studies of ionic liquids with and without metal oxide additions were conducted. FTIR and induction coupled plasma spectroscopy (ICPS) was used in the characterization of the metal oxide dissolved ionic liquid. Electrochemical experiments were conducted using EG&G potentiostat/galvanostat with three electrode cell systems. Cyclic voltammetry was used in the determination of reduction potentials for the deposition of metals. Chronoamperometric experiments were carried out in the potential range of -0.6V to -1.9V for lead and -1.4V to -1.9V for zinc. The deposits were characterized using XRD and SEM-EDS for phase, morphological and elemental analysis. The results showed that pure metal was deposited on the cathode

  4. Oxidation Resistant Graphite Studies

    SciTech Connect

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

  5. Chemistry of [Et4N][MoIV(SPh)(PPh3)(mnt)2] as an analogue of dissimilatory nitrate reductase with its inactivation on substitution of thiolate by chloride.

    PubMed

    Majumdar, Amit; Pal, Kuntal; Sarkar, Sabyasachi

    2006-04-01

    Structural-functional analogue of the reduced site of dissimilatory nitrate reductase is synthesized as [Et4N][MoIV(SPh)(PPh3)(mnt)2].CH2Cl2 (1). PPh3 in 1 is readily dissociated in solution to generate the active site of the reduced site of dissimilatory nitrate reductase. This readily reacts with nitrate. The nitrate reducing system is characterized by substrate saturation kinetics. Oxotransfer to and from substrate has been coupled to produce a catalytic system, NO3- + PPh3 --> NO2- + OPPh3, where NO3- is the substrate for dissimilatory nitrate reductase. The corresponding chloro complex, [Et4N][MoIV(Cl)(PPh3)(mnt)2].CH2Cl2 (2), responds to similar PPh3 dissociation but is unable to react with nitrate, showing the indispensable role of thiolate coordination for such oxotransfer reaction. This investigation provides the initial demonstration of the ligand specificity in a model system similar to single point mutation involving site directed mutagenesis in this class of molybdoenzymes.

  6. Growth of silicon-doped Al0.6Ga0.4N with low carbon concentration at high growth rate using high-flow-rate metal organic vapor phase epitaxy reactor

    NASA Astrophysics Data System (ADS)

    Ikenaga, Kazutada; Mishima, Akira; Yano, Yoshiki; Tabuchi, Toshiya; Matsumoto, Koh

    2016-05-01

    The relationship between the carbon concentration and electrical characteristics of silicon-doped AlGaN (Al > 0.5) was investigated using a high-flow-rate metal organic vapor phase epitaxy (MOVPE) reactor. The carbon concentration and electrical properties of AlGaN (Al > 0.5) were measured as a function of the growth rate, V/III ratio, and growth temperature. The growth rate of Al0.6Ga0.4N was linearly controlled up to 7.2 µm/h under a constant ammonia (NH3) flow rate. However, a decrease in V/III ratio resulted in an increase in carbon concentration to 8 × 1017 cm-3. With increased growth temperature, the carbon concentration decreased to less than 2 × 1017 cm-3 without showing any reduction in growth rate. As a result, n-type Al0.6Ga0.4N with a carrier concentration of 5.4 × 1018 cm-3 and a resistivity of 2.2 × 10-2 Ω·cm was obtained.

  7. CRISPR/Cas9-Mediated Genomic Deletion of the Beta-1, 4 N-acetylgalactosaminyltransferase 1 Gene in Murine P19 Embryonal Carcinoma Cells Results in Low Sensitivity to Botulinum Neurotoxin Type C

    PubMed Central

    Tsukamoto, Kentaro; Ozeki, Chikako; Kohda, Tomoko; Tsuji, Takao

    2015-01-01

    Botulinum neurotoxins produced by Clostridium botulinum cause flaccid paralysis by inhibiting neurotransmitter release at peripheral nerve terminals. Previously, we found that neurons derived from the murine P19 embryonal carcinoma cell line exhibited high sensitivity to botulinum neurotoxin type C. In order to prove the utility of P19 cells for the study of the intracellular mechanism of botulinum neurotoxins, ganglioside-knockout neurons were generated by deletion of the gene encoding beta-1,4 N-acetylgalactosaminyltransferase 1 in P19 cells using the clustered regularly interspaced short palindromic repeats combined with Cas9 (CRISPR/Cas9) system. By using this system, knockout cells could be generated more easily than with previous methods. The sensitivity of the generated beta-1,4 N-acetylgalactosaminyltransferase 1-depleted P19 neurons to botulinum neurotoxin type C was decreased considerably, and the exogenous addition of the gangliosides GD1a, GD1b, and GT1b restored the susceptibility of P19 cells to botulinum neurotoxin type C. In particular, addition of a mixture of these three ganglioside more effectively recovered the sensitivity of knockout cells compared to independent addition of GD1a, GD1b, or GT1b. Consequently, the genome-edited P19 cells generated by the CRISPR/Cas9 system were useful for identifying and defining the intracellular molecules involved in the toxic action of botulinum neurotoxins. PMID:26177297

  8. Monitoring dehydration of the organic-inorganic [(C3H7)4N][SnCl5(H2O)]·2H2O compound using simultaneous thermal and Raman studies

    NASA Astrophysics Data System (ADS)

    Hajlaoui, S.; Chaabane, I.; Guidara, K.; Bulou, A.

    2016-07-01

    In this work we report the experimental studies of the structural phase transition in the [(C3H7)4N]SnCl5(H2O)]·2H2O compound by differential scanning calorimetric (DSC) and Raman spectroscopic. The X-ray powder diffraction study of the [(C3H7)4N][SnCl5(H2O)]·2H2O sample at room temperature showed that this compound is monoclinic and has P121/c1 space group. Differential scanning calorimetric disclosed two types of phase transitions in the temperature range 356-376 (T1) K and at 393 K (T2) characterized, by a loss of water molecules and probably a reconstruction of new anionic parts after T2 transition. The Raman scattering spectra recorded at various temperatures in the wavenumber range from 100 to 3800 cm- 1 covering the domains of existence of changes in the vicinity of the two phase transitions detected by DSC measurement. A detailed study of the spectral parameters (wave number, reduced intensity and the full width at half maximum) as a function of temperature of a chosen band, associated with (νs(Snsbnd O) + νs(Snsbnd Cl)), based on an order-disorder model allowed us to obtain information relative to the activation energy and correlation length.

  9. Aerobic cometabolic degradation of trichloroethene by methane and ammonia oxidizing microorganisms naturally associated with Carex comosa roots.

    PubMed

    Powell, C L; Nogaro, G; Agrawal, A

    2011-06-01

    The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade 150 μg l(-1) TCE effectively at 1.9 mg l(-1) of aqueous CH(4). In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 μg l(-1) TCE at 20 mg l(-1) of NH(4)(+)-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated aquatic environments.

  10. Barium oxide, calcium oxide, magnesia, and alkali oxide free glass

    DOEpatents

    Lu, Peizhen Kathy; Mahapatra, Manoj Kumar

    2013-09-24

    A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.

  11. Design for Oxidation Resistance

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Schaeffer, Jon C.; Barrett, Charles A.

    1997-01-01

    Alloys intended for use in high-temperature environment rely on the formation of a continuous, compact, slow-growing oxide layer for oxidation and hot corrosion resistance. To be protective, this oxide layer must be chemically, thermodynamically stable. Successful alloy design for oxidative environment is best achieved by developing alloys that are capable of forming adherent scales of either alumina (Al2O3), chromia (Cr2O3), or silica (SiO2). In this article, emphasis has been placed on the issue related to high-temperature oxidation of superalloys used in gas turbine engine application. Despite the complexity of these alloys, optimal performance has been associated with protective alumina scale formation. As will be described below, both compositional makeup and protective coatings play key role in providing oxidation protection. Other high-temperature materials described include nickel and titanium aluminide intermetallics, refractory metal, and ceramics.

  12. Infrared rectification in a nanoantenna-coupled metal-oxide-semiconductor tunnel diode.

    PubMed

    Davids, Paul S; Jarecki, Robert L; Starbuck, Andrew; Burckel, D Bruce; Kadlec, Emil A; Ribaudo, Troy; Shaner, Eric A; Peters, David W

    2015-12-01

    Direct rectification of electromagnetic radiation is a well-established method for wireless power conversion in the microwave region of the spectrum, for which conversion efficiencies in excess of 84% have been demonstrated. Scaling to the infrared or optical part of the spectrum requires ultrafast rectification that can only be obtained by direct tunnelling. Many research groups have looked to plasmonics to overcome antenna-scaling limits and to increase the confinement. Recently, surface plasmons on heavily doped Si surfaces were investigated as a way of extending surface-mode confinement to the thermal infrared region. Here we combine a nanostructured metallic surface with a heavily doped Si infrared-reflective ground plane designed to confine infrared radiation in an active electronic direct-conversion device. The interplay of strong infrared photon-phonon coupling and electromagnetic confinement in nanoscale devices is demonstrated to have a large impact on ultrafast electronic tunnelling in metal-oxide-semiconductor (MOS) structures. Infrared dispersion of SiO2 near a longitudinal optical (LO) phonon mode gives large transverse-field confinement in a nanometre-scale oxide-tunnel gap as the wavelength-dependent permittivity changes from 1 to 0, which leads to enhanced electromagnetic fields at material interfaces and a rectified displacement current that provides a direct conversion of infrared radiation into electric current. The spectral and electrical signatures of the nanoantenna-coupled tunnel diodes are examined under broadband blackbody and quantum-cascade laser (QCL) illumination. In the region near the LO phonon resonance, we obtained a measured photoresponsivity of 2.7 mA W(-1) cm(-2) at -0.1 V.

  13. Artificial chemical and magnetic structure at the domain walls of an epitaxial oxide.

    PubMed

    Farokhipoor, S; Magén, C; Venkatesan, S; Íñiguez, J; Daumont, C J M; Rubi, D; Snoeck, E; Mostovoy, M; de Graaf, C; Müller, A; Döblinger, M; Scheu, C; Noheda, B

    2014-11-20

    Progress in nanotechnology requires new approaches to materials synthesis that make it possible to control material functionality down to the smallest scales. An objective of materials research is to achieve enhanced control over the physical properties of materials such as ferromagnets, ferroelectrics and superconductors. In this context, complex oxides and inorganic perovskites are attractive because slight adjustments of their atomic structures can produce large physical responses and result in multiple functionalities. In addition, these materials often contain ferroelastic domains. The intrinsic symmetry breaking that takes place at the domain walls can induce properties absent from the domains themselves, such as magnetic or ferroelectric order and other functionalities, as well as coupling between them. Moreover, large domain wall densities create intense strain gradients, which can also affect the material's properties. Here we show that, owing to large local stresses, domain walls can promote the formation of unusual phases. In this sense, the domain walls can function as nanoscale chemical reactors. We synthesize a two-dimensional ferromagnetic phase at the domain walls of the orthorhombic perovskite terbium manganite (TbMnO3), which was grown in thin layers under epitaxial strain on strontium titanate (SrTiO3) substrates. This phase is yet to be created by standard chemical routes. The density of the two-dimensional sheets can be tuned by changing the film thickness or the substrate lattice parameter (that is, the epitaxial strain), and the distance between sheets can be made as small as 5 nanometres in ultrathin films, such that the new phase at domain walls represents up to 25 per cent of the film volume. The general concept of using domain walls of epitaxial oxides to promote the formation of unusual phases may be applicable to other materials systems, thus giving access to new classes of nanoscale materials for applications in nanoelectronics and

  14. Artificial chemical and magnetic structure at the domain walls of an epitaxial oxide

    NASA Astrophysics Data System (ADS)

    Farokhipoor, S.; Magén, C.; Venkatesan, S.; Íñiguez, J.; Daumont, C. J. M.; Rubi, D.; Snoeck, E.; Mostovoy, M.; de Graaf, C.; Müller, A.; Döblinger, M.; Scheu, C.; Noheda, B.

    2014-11-01

    Progress in nanotechnology requires new approaches to materials synthesis that make it possible to control material functionality down to the smallest scales. An objective of materials research is to achieve enhanced control over the physical properties of materials such as ferromagnets, ferroelectrics and superconductors. In this context, complex oxides and inorganic perovskites are attractive because slight adjustments of their atomic structures can produce large physical responses and result in multiple functionalities. In addition, these materials often contain ferroelastic domains. The intrinsic symmetry breaking that takes place at the domain walls can induce properties absent from the domains themselves, such as magnetic or ferroelectric order and other functionalities, as well as coupling between them. Moreover, large domain wall densities create intense strain gradients, which can also affect the material's properties. Here we show that, owing to large local stresses, domain walls can promote the formation of unusual phases. In this sense, the domain walls can function as nanoscale chemical reactors. We synthesize a two-dimensional ferromagnetic phase at the domain walls of the orthorhombic perovskite terbium manganite (TbMnO3), which was grown in thin layers under epitaxial strain on strontium titanate (SrTiO3) substrates. This phase is yet to be created by standard chemical routes. The density of the two-dimensional sheets can be tuned by changing the film thickness or the substrate lattice parameter (that is, the epitaxial strain), and the distance between sheets can be made as small as 5 nanometres in ultrathin films, such that the new phase at domain walls represents up to 25 per cent of the film volume. The general concept of using domain walls of epitaxial oxides to promote the formation of unusual phases may be applicable to other materials systems, thus giving access to new classes of nanoscale materials for applications in nanoelectronics and

  15. Infrared rectification in a nanoantenna-coupled metal-oxide-semiconductor tunnel diode.

    PubMed

    Davids, Paul S; Jarecki, Robert L; Starbuck, Andrew; Burckel, D Bruce; Kadlec, Emil A; Ribaudo, Troy; Shaner, Eric A; Peters, David W

    2015-12-01

    Direct rectification of electromagnetic radiation is a well-established method for wireless power conversion in the microwave region of the spectrum, for which conversion efficiencies in excess of 84% have been demonstrated. Scaling to the infrared or optical part of the spectrum requires ultrafast rectification that can only be obtained by direct tunnelling. Many research groups have looked to plasmonics to overcome antenna-scaling limits and to increase the confinement. Recently, surface plasmons on heavily doped Si surfaces were investigated as a way of extending surface-mode confinement to the thermal infrared region. Here we combine a nanostructured metallic surface with a heavily doped Si infrared-reflective ground plane designed to confine infrared radiation in an active electronic direct-conversion device. The interplay of strong infrared photon-phonon coupling and electromagnetic confinement in nanoscale devices is demonstrated to have a large impact on ultrafast electronic tunnelling in metal-oxide-semiconductor (MOS) structures. Infrared dispersion of SiO2 near a longitudinal optical (LO) phonon mode gives large transverse-field confinement in a nanometre-scale oxide-tunnel gap as the wavelength-dependent permittivity changes from 1 to 0, which leads to enhanced electromagnetic fields at material interfaces and a rectified displacement current that provides a direct conversion of infrared radiation into electric current. The spectral and electrical signatures of the nanoantenna-coupled tunnel diodes are examined under broadband blackbody and quantum-cascade laser (QCL) illumination. In the region near the LO phonon resonance, we obtained a measured photoresponsivity of 2.7 mA W(-1) cm(-2) at -0.1 V. PMID:26414194

  16. Infrared rectification in a nanoantenna-coupled metal-oxide-semiconductor tunnel diode

    NASA Astrophysics Data System (ADS)

    Davids, Paul S.; Jarecki, Robert L.; Starbuck, Andrew; Burckel, D. Bruce; Kadlec, Emil A.; Ribaudo, Troy; Shaner, Eric A.; Peters, David W.

    2015-12-01

    Direct rectification of electromagnetic radiation is a well-established method for wireless power conversion in the microwave region of the spectrum, for which conversion efficiencies in excess of 84% have been demonstrated. Scaling to the infrared or optical part of the spectrum requires ultrafast rectification that can only be obtained by direct tunnelling. Many research groups have looked to plasmonics to overcome antenna-scaling limits and to increase the confinement. Recently, surface plasmons on heavily doped Si surfaces were investigated as a way of extending surface-mode confinement to the thermal infrared region. Here we combine a nanostructured metallic surface with a heavily doped Si infrared-reflective ground plane designed to confine infrared radiation in an active electronic direct-conversion device. The interplay of strong infrared photon-phonon coupling and electromagnetic confinement in nanoscale devices is demonstrated to have a large impact on ultrafast electronic tunnelling in metal-oxide-semiconductor (MOS) structures. Infrared dispersion of SiO2 near a longitudinal optical (LO) phonon mode gives large transverse-field confinement in a nanometre-scale oxide-tunnel gap as the wavelength-dependent permittivity changes from 1 to 0, which leads to enhanced electromagnetic fields at material interfaces and a rectified displacement current that provides a direct conversion of infrared radiation into electric current. The spectral and electrical signatures of the nanoantenna-coupled tunnel diodes are examined under broadband blackbody and quantum-cascade laser (QCL) illumination. In the region near the LO phonon resonance, we obtained a measured photoresponsivity of 2.7 mA W-1 cm-2 at -0.1 V.

  17. METAL OXIDE NANOPARTICLES

    SciTech Connect

    FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

    2007-10-01

    This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

  18. OXIDATION OF TRANSURANIC ELEMENTS

    DOEpatents

    Moore, R.L.

    1959-02-17

    A method is reported for oxidizing neptunium or plutonium in the presence of cerous values without also oxidizing the cerous values. The method consists in treating an aqueous 1N nitric acid solution, containing such cerous values together with the trivalent transuranic elements, with a quantity of hydrogen peroxide stoichiometrically sufficient to oxidize the transuranic values to the hexavalent state, and digesting the solution at room temperature.

  19. Multifunctional Oxide Heterostructures

    SciTech Connect

    Tsymbal, E Y; Dagotto, Elbio R; Eom, Professor Chang-Beom; Ramesh, Ramamoorthy

    2012-01-01

    This book is devoted to the rapidly developing field of oxide thin-films and heterostructures. Oxide materials combined with atomic-scale precision in a heterostructure exhibit an abundance of macroscopic physical properties involving the strong coupling between the electronic, spin, and structural degrees of freedom, and the interplay between magnetism, ferroelectricity, and conductivity. Recent advances in thin-film deposition and characterization techniques made possible the experimental realization of such oxide heterostructures, promising novel functionalities and device concepts.

  20. Combination of bexarotene and the retinoid CD1530 reduces murine oral-cavity carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide

    PubMed Central

    Tang, Xiao-Han; Osei-Sarfo, Kwame; Urvalek, Alison M.; Zhang, Tuo; Scognamiglio, Theresa; Gudas, Lorraine J.

    2014-01-01

    We investigated the effects of bexarotene (a retinoid X receptor agonist), CD1530 (a retinoic acid receptor γ selective agonist), and the combination of these two drugs for the prevention of oral carcinogenesis induced by the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in a mouse model of human oral-cavity and esophageal squamous-cell carcinoma previously generated in our laboratory. We observed decreased numbers of neoplastic tongue lesions and reduced lesion severity in the 4-NQO plus CD1530 (4N+C) and 4-NQO plus bexarotene plus CD1530 (4N+B+C) groups compared with the 4-NQO group. RNA-Seq analyses showed increases in transcripts in cell proliferation/cell cycle progression pathways in the 4-NQO vs. the untreated group. In addition, β-catenin and matrix metallopeptidase 9 (MMP9) protein levels and reactive oxygen species (ROS), as assessed by 4-hydroxynonenal (4-HNE) staining, were elevated in tongue tissues 17 wk after the termination of the 4-NQO treatment. The 4N+B, 4N+C, and 4N+B+C groups showed dramatically lower levels of β-catenin, MMP9, and 4-HNE staining compared with the 4-NQO group. The major reduction in 4-HNE staining in the retinoid treatment groups suggests a novel mechanism of action, reduction of ROS, by which bexarotene and CD1530 inhibit carcinogenesis. PMID:24927566