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Sample records for intercalator displacement-based discovery

  1. DISPLACEMENT BASED SEISMIC DESIGN METHODS.

    SciTech Connect

    HOFMAYER,C.MILLER,C.WANG,Y.COSTELLO,J.

    2003-07-15

    A research effort was undertaken to determine the need for any changes to USNRC's seismic regulatory practice to reflect the move, in the earthquake engineering community, toward using expected displacement rather than force (or stress) as the basis for assessing design adequacy. The research explored the extent to which displacement based seismic design methods, such as given in FEMA 273, could be useful for reviewing nuclear power stations. Two structures common to nuclear power plants were chosen to compare the results of the analysis models used. The first structure is a four-story frame structure with shear walls providing the primary lateral load system, referred herein as the shear wall model. The second structure is the turbine building of the Diablo Canyon nuclear power plant. The models were analyzed using both displacement based (pushover) analysis and nonlinear dynamic analysis. In addition, for the shear wall model an elastic analysis with ductility factors applied was also performed. The objectives of the work were to compare the results between the analyses, and to develop insights regarding the work that would be needed before the displacement based analysis methodology could be considered applicable to facilities licensed by the NRC. A summary of the research results, which were published in NUREGICR-6719 in July 2001, is presented in this paper.

  2. Displacement Based Seismic Design Criteria

    SciTech Connect

    Costello, J.F.; Hofmayer, C.; Park, Y.J.

    1999-03-29

    The USNRC has initiated a project to determine if any of the likely revisions to traditional earthquake engineering practice are relevant to seismic design of the specialized structures, systems and components of nuclear power plants and of such significance to suggest that a change in design practice might be warranted. As part of the initial phase of this study, a literature survey was conducted on the recent changes in seismic design codes/standards, on-going activities of code-writing organizations/communities, and published documents on displacement-based design methods. This paper provides a summary of recent changes in building codes and on-going activities for future codes. It also discusses some technical issues for further consideration.

  3. DISPLACEMENT BASED SEISMIC DESIGN CRITERIA

    SciTech Connect

    HOFMAYER,C.H.

    1999-03-29

    The USNRC has initiated a project to determine if any of the likely revisions to traditional earthquake engineering practice are relevant to seismic design of the specialized structures, systems and components of nuclear power plants and of such significance to suggest that a change in design practice might be warranted. As part of the initial phase of this study, a literature survey was conducted on the recent changes in seismic design codes/standards, on-going activities of code-writing organizations/communities, and published documents on displacement-based design methods. This paper provides a summary of recent changes in building codes and on-going activities for future codes. It also discusses some technical issues for further consideration.

  4. Harnessing DNA intercalation.

    PubMed

    Persil, Ozgül; Hud, Nicholas V

    2007-10-01

    Numerous small molecules are known to bind to DNA through base pair intercalation. Fluorescent dyes commonly used for nucleic acid staining, such as ethidium, are familiar examples. Biological and physical studies of DNA intercalation have historically been motivated by mutation and drug discovery research. However, this same mode of binding is now being harnessed for the creation of novel molecular assemblies. Recent studies have used DNA scaffolds and intercalators to construct supramolecular assemblies that function as fluorescent 'nanotags' for cell labeling. Other studies have demonstrated how intercalators can be used to promote the formation of otherwise unstable nucleic acid assemblies. These applications illustrate how intercalators can be used to facilitate and expand DNA-based nanotechnology. PMID:17825446

  5. Discovery

    ERIC Educational Resources Information Center

    de Mestre, Neville

    2010-01-01

    All common fractions can be written in decimal form. In this Discovery article, the author suggests that teachers ask their students to calculate the decimals by actually doing the divisions themselves, and later on they can use a calculator to check their answers. This article presents a lesson based on the research of Bolt (1982).

  6. Graphene spintronics: Intercalated boosters

    NASA Astrophysics Data System (ADS)

    Kralj, Marko

    2015-01-01

    Graphene is a candidate spintronics material, but its weak intrinsic spin-orbit coupling is problematic. Intercalating graphene on an iridium substrate with islands of lead is now shown to induce a strong, spatially varying spin-orbit coupling.

  7. Measurement of chest wall displacement based on terahertz wave

    NASA Astrophysics Data System (ADS)

    Li, Hui; Lv, Hao; Jiao, Teng; Lu, Guohua; Li, Sheng; Li, Zhao; Liu, Miao; Jing, Xijing; Wang, Jianqi

    2015-02-01

    Measurement of chest wall displacement is an important approach for measuring mechanics of chest wall, which has considerable significance for assessing respiratory system and diagnosing pulmonary diseases. However, existing optical methods for measuring chest wall displacement are inconvenient for some specific patients such as the female patients and the patients with bandaged chest. In this letter, we proposed a method for measuring chest wall displacement based on terahertz wave and established corresponding mathematic model and set up a terahertz measurement system. The main advantages of this method are that it can measure the chest wall displacement of the subjects without taking off clothes or arranging any markers. To validate this method and assess the performance of the terahertz system, in vitro, the displacement of a water module driven by a linear guide rail was measured by the terahertz system and compared with the actual displacement of the water module. The results showed that the waveforms measured with two methods have a good agreement, and the relative error is less than 5% and sufficiently good for measurement demands. In vivo, the synchronous experiment was performed on five human volunteers with the terahertz system and a respiratory belt transducer. The results demonstrate that this method has good performance and promising prospects for measuring chest wall displacement.

  8. Superconductivity in graphite intercalation compounds

    SciTech Connect

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P. M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.

  9. Superconductivity in graphite intercalation compounds

    DOE PAGESBeta

    Smith, Robert P.; Weller, Thomas E.; Howard, Christopher A.; Dean, Mark P. M.; Rahnejat, Kaveh C.; Saxena, Siddharth S.; Ellerby, Mark

    2015-02-26

    This study examines the field of superconductivity in the class of materials known as graphite intercalation compounds which has a history dating back to the 1960s. This paper recontextualizes the field in light of the discovery of superconductivity in CaC₆ and YbC₆ in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic statesmore » and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.« less

  10. Efficiency Improvements to the Displacement Based Multilevel Structural Optimization Algorithm

    NASA Technical Reports Server (NTRS)

    Plunkett, C. L.; Striz, A. G.; Sobieszczanski-Sobieski, J.

    2001-01-01

    Multilevel Structural Optimization (MSO) continues to be an area of research interest in engineering optimization. In the present project, the weight optimization of beams and trusses using Displacement based Multilevel Structural Optimization (DMSO), a member of the MSO set of methodologies, is investigated. In the DMSO approach, the optimization task is subdivided into a single system and multiple subsystems level optimizations. The system level optimization minimizes the load unbalance resulting from the use of displacement functions to approximate the structural displacements. The function coefficients are then the design variables. Alternately, the system level optimization can be solved using the displacements themselves as design variables, as was shown in previous research. Both approaches ensure that the calculated loads match the applied loads. In the subsystems level, the weight of the structure is minimized using the element dimensions as design variables. The approach is expected to be very efficient for large structures, since parallel computing can be utilized in the different levels of the problem. In this paper, the method is applied to a one-dimensional beam and a large three-dimensional truss. The beam was tested to study possible simplifications to the system level optimization. In previous research, polynomials were used to approximate the global nodal displacements. The number of coefficients of the polynomials equally matched the number of degrees of freedom of the problem. Here it was desired to see if it is possible to only match a subset of the degrees of freedom in the system level. This would lead to a simplification of the system level, with a resulting increase in overall efficiency. However, the methods tested for this type of system level simplification did not yield positive results. The large truss was utilized to test further improvements in the efficiency of DMSO. In previous work, parallel processing was applied to the

  11. Thin flexible intercalation anodes

    SciTech Connect

    Levy, S.C.; Cieslak, W.R.; Klassen, S.E.; Lagasse, R.R.

    1994-10-01

    Poly(acrylonitrile) fibers have been pyrolyzed under various conditions to form flexible carbon yarns capable of intercalating lithium ions. These fibers have also been formed into both woven and non woven cloths. Potentiostatic, potentiodynamic and galvanostatic tests have been conducted with these materials in several electrolytes. In some tests, a potential hold was used after each constant current charge and discharge. These tests have shown some of these flexible materials to reversibly intercalate lithium ions to levels that are suitable for use as a practical battery anode.

  12. Graphite fiber intercalation: Dynamics of the bromine intercalation process

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Zinolabedini, R.

    1985-01-01

    The resistance of pitch-based graphite fibers was monitored, in situ, during a series of bromine intercalation experiments. The threshold pressure for the bromine intercalation of pitch-based fibers was estimated to be 102 torr. When the bromine atmosphere was removed from the reaction chamber, the resistivity of the intercalated graphite fibers increased consistently. This increase was attributed to loss of bromine from the perimeter of the fiber. The loss was confirmed by mapping the bromine concentration across the diameter of single intercalated fibers with either energy dispersive spectroscopy or scanning Auger microscopy. A statistical study comparing fibers intercalated in bromine vapor with fibers intercalated in bromine liquid showed that similar products were obtained with both methods of intercalation.

  13. Photofunctions of intercalation compounds

    SciTech Connect

    Ogawa, Makoto; Kuroda, Kazuyuki

    1995-03-01

    In this article, the authors review the studies on the photofunctions of intercalation compounds. (The structures and properties of host materials which have been used for immobilizing photoactive species have been summarized in the following section.) some of these studies are for the purpose of characterizing the properties of host materials and host-guest systems, and others are for the purpose of contributing to future practical applications. The well-defined layered structures as well as the ability to accommodate guest species on the surface of the layers are very useful for organizing photoactive species to evaluate and control the photofunctions. Table 1 summarizes the characteristics of typical host-guest systems studied for immobilizing photoactive species. Attention is mainly focused on the role of layered structure on the organization of photoactive species; the photofunctions of intercalation compounds are discussed only in connection with the microscopic structures. 321 refs.

  14. Intercalating oleylamines in graphite oxide.

    PubMed

    Yang, Kaikun; Liang, Si; Zou, Lianfeng; Huang, Liwei; Park, Cheol; Zhu, Lisheng; Fang, Jiye; Fu, Qiang; Wang, Howard

    2012-02-01

    Graphite oxide has been synthesized from raw graphite particles and been treated with various mass amounts of oleylamine as intercalants to form intercalation compounds. X-ray diffraction patterns reveal that the inter-sheet distances strongly depend on the graphite oxide to oleylamine mass ratios. The equilibrium-like behavior implies diffusion-dominated oleylamine adsorption on graphite oxide in solution and excluded volume intercalations among oleylamine-adsorbed graphite oxide during restacking. The intercalation compounds are soluble in organic solvents, and their applications in the fabrication of transparent and conductive coatings have been demonstrated. PMID:22229856

  15. Stacking interactions and DNA intercalation

    SciTech Connect

    Li, Dr. Shen; Cooper, Valentino R; Thonhauser, Prof. Timo; Lundqvist, Prof. Bengt I.; Langreth, David C.

    2009-01-01

    The relationship between stacking interactions and the intercalation of proflavine and ellipticine within DNA is investigated using a nonempirical van der Waals density functional for the correlation energy. Our results, employing a binary stack model, highlight fundamental, qualitative differences between base-pair base-pair interactions and that of the stacked intercalator base pair system. Most notable result is the paucity of torque which so distinctively defines the Twist of DNA. Surprisingly, this model, when combined with a constraint on the twist of the surrounding base-pair steps to match the observed unwinding of the sugar-phosphate backbone, was sufficient for explaining the experimentally observed proflavine intercalator configuration. Our extensive mapping of the potential energy surface of base-pair intercalator interactions can provide valuable information for future nonempirical studies of DNA intercalation dynamics.

  16. Durability of Intercalated Graphite Epoxy Composites in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Davidson, Michelle L.; Shively, Rhonda

    1996-01-01

    The electrical conductivity of graphite epoxy composites can be substantially increased by intercalating (inserting guest atoms or molecules between the graphene planes) the graphite fibers before composite formation. The resulting high strength, low density, electrically conducting composites have been proposed for EMI shielding in spacecraft. Questions have been raised, however, about their durability in the space environment, especially with respect to outgassing of the intercalates, which are corrosive species such as bromine. To answer those concerns, six samples of bromine intercalated graphite epoxy composites were included in the third Evaluation of Oxygen Interaction with Materials (EOIM-3) experiment flown on the Space Shuttle Discovery (STS-46). Changes in electrical conductivity, optical reflectance, surface texture, and mass loss for SiO2 protected and unprotected samples were measured after being exposed to the LEO environment for 42 hours. SiO2 protected samples showed no degradation, verifying conventional protection strategies are applicable to bromine intercalated composites. The unprotected samples showed that bromine intercalation does not alter the degradation of graphite-epoxy composites. No bromine was detected to have been released by the fibers allaying fears that outgassing could be disruptive to the sensitive electronics the EMI shield is meant to protect.

  17. Superconductivity in alkali metal intercalated iron selenides.

    PubMed

    Krzton-Maziopa, A; Svitlyk, V; Pomjakushina, E; Puzniak, R; Conder, K

    2016-07-27

    Alkali metal intercalated iron selenide superconductors A x Fe2-y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations. PMID:27248118

  18. Superconductivity in alkali metal intercalated iron selenides

    NASA Astrophysics Data System (ADS)

    Krzton-Maziopa, A.; Svitlyk, V.; Pomjakushina, E.; Puzniak, R.; Conder, K.

    2016-07-01

    Alkali metal intercalated iron selenide superconductors A x Fe2‑y Se2 (where A  =  K, Rb, Cs, Tl/K, and Tl/Rb) are characterized by several unique properties, which were not revealed in other superconducting materials. The compounds crystallize in overall simple layered structure with FeSe layers intercalated with alkali metal. The structure turned out to be pretty complex as the existing Fe-vacancies order below ~550 K, which further leads to an antiferromagnetic ordering with Néel temperature fairly above room temperature. At even lower temperatures a phase separation is observed. While one of these phases stays magnetic down to the lowest temperatures the second is becoming superconducting below ~30 K. All these effects give rise to complex relationships between the structure, magnetism and superconductivity. In particular the iron vacancy ordering, linked with a long-range magnetic order and a mesoscopic phase separation, is assumed to be an intrinsic property of the system. Since the discovery of superconductivity in those compounds in 2010 they were investigated very extensively. Results of the studies conducted using a variety of experimental techniques and performed during the last five years were published in hundreds of reports. The present paper reviews scientific work concerning methods of synthesis and crystal growth, structural and superconducting properties as well as pressure investigations.

  19. Superconductivity in intercalated molybdenum disulfide.

    NASA Technical Reports Server (NTRS)

    Somoano, R.; Hadek, V.; Rembaum, A.

    1972-01-01

    X-ray studies show the existence of two different types of expansions of the intercalated unit cell in both Na and K compounds. Two different phases are also indicated in the superconducting behavior of the K compound. All intercalated samples studied show a superconducting transition. K and Rb compounds become superconductors in the temperature range from 6.5 to 6.0 K. The Na compounds become superconductors at about 4.5 K. In all cases, the superconductivity disappears upon a short exposure of the sample to air. This phenomenon confirms that the superconductivity is due to the presence of the alkali metal.

  20. The Mechanics of Cell Intercalation

    NASA Astrophysics Data System (ADS)

    Mani, Madhav; Shraiman, Boris; Lecuit, Thomas

    2014-03-01

    Cell-intercalation involves the cytoskeleton-driven exchange of cellular neighbors. Developmental cues produce directional biases in the pattern of neighbor-exchanges, resulting in the alteration of tissue shape - morphogenesis. Focusing on cell-intercalation during early fly development, I will address both static and dynamical aspects. A quantitative correspondence is drawn between cytoskeletal levels, stresses and geometry. This construction of a constitutive law, relies on a novel image analysis tool that infers mechanical features of the cellular lattice from live imaging (from the Lecuit Lab, Marseilles). Building on our understanding of these static aspects, we construct a phenomenological, and physically-motivated, model for cytoskeletal remodeling based on temporal correlation analyses. This model predicts the qualitative phases of junctional states, insights into the T1 event that mediates intercalation, and several of the collective properties of cell-intercalation that have remained unaddressed so far - we go on to validate these predictions. We conclude with introducing the idea that tissue-wide anisotropies, central to morphogenesis and patterning in the embryo, can emerge as a consequences of the collective aspects of mechanical interactions.

  1. ASSESSMENT OF THE RELEVANCE OF DISPLACEMENT BASED DESIGN METHODS/CRITERIA TO NUCLEAR PLANT STRUCTURES.

    SciTech Connect

    HOFMAYER,C.; MILLER,C.; WANG,Y.; COSTELLO,J.

    2001-08-12

    Revisions to the USNRC Regulatory Guides and Standard Review Plan Sections devoted to earthquake engineering practice are currently in process. The intent is to reflect changes in engineering practice that have evolved in the twenty years that have passed since those criteria were originally published. Additionally, field observations of the effects of the Northridge (1994) and Kobe (1995) earthquakes have inspired some reassessment in the technical community about certain aspects of design practice. In particular, questions have arisen about the effectiveness of basing earthquake resistant designs on resistance to seismic forces and, then evaluating tolerability of the expected displacements. Therefore, a research effort was undertaken to examine the implications for NRC's seismic practice of the move, in the earthquake engineering community, toward using expected displacement rather than force (or stress) as the basis for assessing design adequacy. The results of the NRC sponsored research on this subject are reported in this paper. A slow trend toward the utilization of displacement based methods for design was noted. However, there is a more rapid trend toward the use of displacement based methods for seismic evaluation of existing facilities. A document known as FEMA 273, has been developed and is being used as the basis for the design of modifications to enhance the seismic capability of existing non-nuclear facilities. The research concluded that displacement based methods, such as given in FEMA 273, may be useful for seismic margin studies of existing nuclear power stations. They are unlikely to be useful for the basic design of new stations since nuclear power stations are designed to remain elastic during a seismic event. They could, however, be useful for estimating the margins associated with that design.

  2. Intercalation of cyclic ketones into vanadyl phosphate

    SciTech Connect

    Zima, Vitezslav . E-mail: vitezslav.zima@upce.cz; Melanova, Klara; Benes, Ludvik; Trchova, Miroslava; Dybal, Jiri

    2005-01-15

    Intercalation compounds of vanadyl phosphate with cyclic ketones (cyclopentanone, cyclohexanone, 4-methylcyclohexanone, and 1,4-cyclohexanedione) were prepared from corresponding propanol or ethanol intercalates by a molecular exchange. The intercalates prepared were characterized using powder X-ray diffraction and thermogravimetric analysis. The intercalates are stable in dry environment and decompose slowly in humid air. Infrared and Raman spectra indicate that carbonyl oxygens of the guest molecules are coordinated to the vanadium atoms of the host layers. The local structure and interactions in the cyclopentanone intercalate have been suggested on the basis of quantum chemical calculations.

  3. Graphite fiber intercalation: Basic properties of copper chloride intercalated fibers

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Miller, J. D.

    1986-01-01

    In situ resistance measurements were used to follow the intercalation of copper chloride in pitch-based fibers. Subsequent single fiber resistivity measurements reveal a large range of resistivities, from 13 to 160 micro-ohms cm. Additional density measurements reveal a bimodal distribution of mass densities. The dense fibers have lower resistivities and correspond to the stage III compound identified by X-ray diffraction. Neither resistivity nor density correlate with diameter. Both energy dispersive spectroscopy and mass density data suggest that excess chlorine resides in the intercalated fiber, resulting in a stoichiometry of C4.9n CuCl2.5 (where n is the stage number) for the denser fibers. Finally, thermogravimetric analysis shows a 33 percent loss in mass upon heating to 700C. This loss in mass is attributed to loss of both chlorine and carbon.

  4. The mechanism of caesium intercalation of graphene

    NASA Astrophysics Data System (ADS)

    Petrović, M.; Šrut Rakić, I.; Runte, S.; Busse, C.; Sadowski, J. T.; Lazić, P.; Pletikosić, I.; Pan, Z.-H.; Milun, M.; Pervan, P.; Atodiresei, N.; Brako, R.; Šokčević, D.; Valla, T.; Michely, T.; Kralj, M.

    2013-11-01

    Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene, can be manipulated by the inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers; however, the microscopic mechanisms and dynamics of these processes are not well understood. Here we report on a novel mechanism for intercalation and entrapment of alkali atoms under epitaxial graphene. We find that the intercalation is adjusted by the van der Waals interaction, with the dynamics governed by defects anchored to graphene wrinkles. Our findings are relevant for the future design and application of graphene-based nano-structures. Similar mechanisms can also have a role for intercalation of layered materials.

  5. The mechanism of caesium intercalation of graphene.

    PubMed

    Petrović, M; Šrut Rakić, I; Runte, S; Busse, C; Sadowski, J T; Lazić, P; Pletikosić, I; Pan, Z-H; Milun, M; Pervan, P; Atodiresei, N; Brako, R; Šokčević, D; Valla, T; Michely, T; Kralj, M

    2013-01-01

    Properties of many layered materials, including copper- and iron-based superconductors, topological insulators, graphite and epitaxial graphene, can be manipulated by the inclusion of different atomic and molecular species between the layers via a process known as intercalation. For example, intercalation in graphite can lead to superconductivity and is crucial in the working cycle of modern batteries and supercapacitors. Intercalation involves complex diffusion processes along and across the layers; however, the microscopic mechanisms and dynamics of these processes are not well understood. Here we report on a novel mechanism for intercalation and entrapment of alkali atoms under epitaxial graphene. We find that the intercalation is adjusted by the van der Waals interaction, with the dynamics governed by defects anchored to graphene wrinkles. Our findings are relevant for the future design and application of graphene-based nano-structures. Similar mechanisms can also have a role for intercalation of layered materials. PMID:24212475

  6. Alkali metal intercalates of molybdenum disulfide.

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1973-01-01

    Study of some of the physicochemical properties of compounds obtained by subjecting natural molybdenite and single crystals of molybdenum disulfide grown by chemical vapor transport to intercalation with the alkali group of metals (Li, Na, K, Rb, and Cs) by means of the liquid ammonia technique. Reported data and results include: (1) the intercalation of the entire alkali metal group, (2) stoichiometries and X-ray data on all of the compounds, and (3) superconductivity data for all the intercalation compounds.

  7. The alkaline earth intercalates of molybdenum disulfide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.; Samson, S.; Woollam, J. A.

    1975-01-01

    Molybdenum disulfide has been intercalated with calcium and strontium by means of the liquid ammonia technique. Chemical, X-ray, and superconductivity data are presented. The X-ray data reveal a lowering of crystal symmetry and increase of complexity of the structure upon intercalation with the alkaline earth metals. The Ca and Sr intercalates start to superconduct at 4 and 5.6 K, respectively, and show considerable anisotropy regarding the critical magnetic field.

  8. Environmental stability of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, J. R.; Jaworske, D. A.

    1985-01-01

    Graphite fibers intercalated with bromine, iodine monochloride, ferric chloride, and cupric chloride were subjected to stability tests under four environments which are encountered by engineering materials in the aerospace industry: ambient laboratory conditions, as would be experienced during handling operations and terrestrial applications; high vacuum, as would be experienced in space applications; high humidity, as would be experienced in marine applications; and high temperature, as would be experienced in some processing steps and applications. Monitoring the resistance of the fibers at ambient laboratory conditions revealed that only the ferric chloride intercalated fibers were unstable, due to absorption of water from the air. All four types of intercalated fibers were unstable, due to absorption of water from the air. All four types of intercalated fibers were stable for long periods under high vacuum. Ferric chloride, cupric chloride, and iodine monochloride intercalated fibers were sensitive to high humidity conditions. All intercalated fibers began to degrade above 250 C. The order of their thermal stability, from lowest to highest, was cupric chloride, iodine monochloride, bromine, and ferric chloride. Of the four types of intercalated fibers tested, the bromine intercalated fibers appear to have the most potential for application, based on environmental stability.

  9. Intercalation chemistry of zirconium 4-sulfophenylphosphonate

    SciTech Connect

    Svoboda, Jan; Zima, Vítězslav; Melánová, Klára; Beneš, Ludvík; Trchová, Miroslava

    2013-12-15

    Zirconium 4-sulfophenylphosphonate is a layered material which can be employed as a host for the intercalation reactions with basic molecules. A wide range of organic compounds were chosen to represent intercalation ability of zirconium 4-sulfophenylphosphonate. These were a series of alkylamines from methylamine to dodecylamine, 1,4-phenylenediamine, p-toluidine, 1,8-diaminonaphthalene, 1-aminopyrene, imidazole, pyridine, 4,4′-bipyridine, poly(ethylene imine), and a series of amino acids from glycine to 6-aminocaproic acid. The prepared compounds were characterized by powder X-ray diffraction, thermogravimetry analysis and IR spectroscopy and probable arrangement of the guest molecules in the interlayer space of the host is proposed based on the interlayer distance of the prepared intercalates and amount of the intercalated guest molecules. - Graphical abstract: Nitrogen-containing organic compounds can be intercalated into the interlayer space of zirconium 4-sulfophenylphosphonate. - Highlights: • Zirconium 4-sulfophenylphosphonate was examined as a host material in intercalation chemistry. • A wide range of nitrogen-containing organic compounds were intercalated. • Possible arrangement of the intercalated species is described.

  10. Intercalation of lactones into vanadyl phosphate

    NASA Astrophysics Data System (ADS)

    Melánová, Klára; Beneš, Ludvík; Svoboda, Jan; Zima, Vítězslav

    2006-05-01

    Intercalates of vanadyl phosphate with α-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-valerolactone, and ɛ-caprolactone were prepared by a displacement reaction of ethanol-intercalated VOPO4. As follows from the results of elemental analyses and thermogravimetry, intercalates contain about one molecule of the guest per formula unit. The diffractograms of the intercalates show a series of sharp (001) reflections, (200) reflection and some (hkl) lines with low intensity. The tetragonal lattice parameters of the intercalates were calculated. Both δ-valerolactone and ɛ-caprolactone intercalates are stable in air. The intercalates of lactones with side aliphatic chains are less stable. The CO stretching vibration in IR spectra of the intercalates prepared was shifted to lower wavenumbers in comparison with spectra of the pure guests, indicating that lactones are anchored to the host layers by their carbonyl oxygen. Analogously to the arrangement of γ-butyrolactone, also arrangement of molecules of other lactones in the interlayer space of the host layers was proposed.

  11. Triplex glue by synthesizing conjugated flexible intercalators.

    PubMed

    Pedersen, Erik B; Osman, Amany M A; Globisch, Daniel; Paramasivam, Manikandan; Cogoi, Susanna; Bomholt, Niels; Jørgensen, Per T; Xodo, Luigi E; Filichev, Vyacheslav V

    2008-01-01

    Bulge insertions of conjugated intercalators into the DNA triplex structure are found to give a dramatic contribution to the triplex stability. On the other hand insertions of conjugated intercalators are found to diminish quadruplex structures and in this way breaking down the self association of G-rich oligonucleotides under physiologically potassium ion conditions. A large number of intercalators are described here and they all result in dramatic increases of thermal stability of the corresponding triplexes. Another interesting aspect of conjugated intercalators is their use for assembling alternate strand triplexes. Targeting of neighbouring purine sequences on each their strand in the duplex DNA is a challenge for the 5'- 5' connectivity of the TFOs because of a large distance between the 5'-ends. The intercalator approach offers a linkage with the proper combination of flexibility and rigidity to produce alternate strand triplexes with higher stability than a similar wild type triplex of the same total length. PMID:18776241

  12. Displacement-Based Seismic Design Procedure for Framed Buildings with Dissipative Braces Part I: Theoretical formulation

    SciTech Connect

    Mazza, Fabio; Vulcano, Alfonso

    2008-07-08

    The insertion of steel braces equipped with dissipative devices proves to be very effective in order to enhance the performance of a framed building under horizontal seismic loads. Multi-level design criteria were proposed according to the Performance-Based Design, in order to get, for a specific level of the seismic intensity, a designated performance objective of the building (e.g., an assigned damage level of either the framed structure or non-structural elements). In this paper a design procedure aiming to proportion braces with hysteretic dampers in order to attain, for a specific level of the seismic intensity, a designated performance level of the building is proposed. Exactly, a proportional stiffness criterion, which assumes the elastic lateral storey-stiffness due to the braces proportional to that of the unbraced frame, is combined with the Direct Displacement-Based Design, in which the design starts from target deformations. A computer code has been prepared for the nonlinear static and dynamic analyses, using a step-by-step procedure. Frame members and hysteretic dampers are idealized by bilinear models.

  13. Displacement-Based Seismic Design Procedure for Framed Buildings with Dissipative Braces Part II: Numerical Results

    SciTech Connect

    Mazza, Fabio; Vulcano, Alfonso

    2008-07-08

    For a widespread application of dissipative braces to protect framed buildings against seismic loads, practical and reliable design procedures are needed. In this paper a design procedure based on the Direct Displacement-Based Design approach is adopted, assuming the elastic lateral storey-stiffness of the damped braces proportional to that of the unbraced frame. To check the effectiveness of the design procedure, presented in an associate paper, a six-storey reinforced concrete plane frame, representative of a medium-rise symmetric framed building, is considered as primary test structure; this structure, designed in a medium-risk region, is supposed to be retrofitted as in a high-risk region, by insertion of diagonal braces equipped with hysteretic dampers. A numerical investigation is carried out to study the nonlinear static and dynamic responses of the primary and the damped braced test structures, using step-by-step procedures described in the associate paper mentioned above; the behaviour of frame members and hysteretic dampers is idealized by bilinear models. Real and artificial accelerograms, matching EC8 response spectrum for a medium soil class, are considered for dynamic analyses.

  14. Displacement-based seismic design of flat slab-shear wall buildings

    NASA Astrophysics Data System (ADS)

    Sen, Subhajit; Singh, Yogendra

    2016-06-01

    Flat slab system is becoming widely popular for multistory buildings due to its several advantages. However, the performance of flat slab buildings under earthquake loading is unsatisfactory due to their vulnerability to punching shear failure. Several national design codes provide guidelines for designing flat slab system under gravity load only. Nevertheless, flat slab buildings are also being constructed in high seismicity regions. In this paper, performance of flat slab buildings of various heights, designed for gravity load alone according to code, is evaluated under earthquake loading as per ASCE/SEI 41 methodology. Continuity of slab bottom reinforcement through column cage improves the performance of flat slab buildings to some extent, but it is observed that these flat slab systems are not adequate in high seismicity areas and need additional primary lateral load resisting systems such as shear walls. A displacement-based method is proposed to proportion shear walls as primary lateral load resisting elements to ensure satisfactory performance. The methodology is validated using design examples of flat slab buildings with various heights.

  15. A complete solution of cartographic displacement based on elastic beams model and Delaunay triangulation

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Guo, Q.; Sun, Y.

    2014-04-01

    In map production and generalization, it is inevitable to arise some spatial conflicts, but the detection and resolution of these spatial conflicts still requires manual operation. It is become a bottleneck hindering the development of automated cartographic generalization. Displacement is the most useful contextual operator that is often used for resolving the conflicts arising between two or more map objects. Automated generalization researches have reported many approaches of displacement including sequential approaches and optimization approaches. As an excellent optimization approach on the basis of energy minimization principles, elastic beams model has been used in resolving displacement problem of roads and buildings for several times. However, to realize a complete displacement solution, techniques of conflict detection and spatial context analysis should be also take into consideration. So we proposed a complete solution of displacement based on the combined use of elastic beams model and constrained Delaunay triangulation (CDT) in this paper. The solution designed as a cyclic and iterative process containing two phases: detection phase and displacement phase. In detection phase, CDT of map is use to detect proximity conflicts, identify spatial relationships and structures, and construct auxiliary structure, so as to support the displacement phase on the basis of elastic beams. In addition, for the improvements of displacement algorithm, a method for adaptive parameters setting and a new iterative strategy are put forward. Finally, we implemented our solution on a testing map generalization platform, and successfully tested it against 2 hand-generated test datasets of roads and buildings respectively.

  16. Graphite intercalation compound with iodine as the major intercalate

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh; Kucera, Donald

    1994-01-01

    Halogenated graphite CBr(x)I(y) (I less than y/x less than 10) was made by exposing graphite materials to either pure Br2 or an I2/Br2/HBr mixture to initiate the reaction, and then to iodine vapor containing a small amount of Br2/HBr/IBr to complete the intercalation reaction. Wetting of the graphite materials by the I2/Br2/HBr mixture is needed to start the reaction, and a small amount of Br2/HBr/IBr is needed to complete the charge transfer between iodine and carbon. The interplanar spacings for the graphite materials need to be in the 3.35 to 3.41 A range. The X-ray diffraction data obtained from the halogenated HOPG indicate that the distance between the two carbon layers containing intercalate is 7.25 A. Electrical resistivity of the fiber product is from 3 to 6.5 times the pristine value, The presence of a small amount of isoprene rubber in the reaction significantly increased the iodine-to-bromine ratio in the product. In this reaction, rubber is known to generate HBr and to slowly remove bromine from the vapor. The halogenation generally caused a 22 percent to 25 percent weight increase. The halogens were found uniformly distributed in the product interior. However, although the surface contains very little iodine, it has high concentrations of bromine and oxygen. It is believed that the high concentrations of bromine and oxygen in this surface cause the halogenated fiber to be more resistant to structural damage during subsequent fluorination to fabricate graphite fluoride fibers.

  17. Electrochemical Li-Ion Intercalation in Octacyanotungstate-Bridged Coordination Polymer with Evidence of Three Magnetic Regimes.

    PubMed

    Long, Jérôme; Asakura, Daisuke; Okubo, Masashi; Yamada, Atsuo; Guari, Yannick; Larionova, Joulia

    2016-08-01

    Discovery of novel compounds capable of electrochemical ion intercalation is a primary step toward development of advanced electrochemical devices such as batteries. Although cyano-bridged coordination polymers including Prussian blue analogues have been intensively investigated as ion intercalation materials, the solid-state electrochemistry of the octacyanotungstate-bridged coordination polymer has not been investigated. Here, we demonstrate that an octacyanotungstate-bridged coordination polymer Tb(H2O)5[W(CN)8] operates as a Li(+)-ion intercalation electrode material. The detailed magnetic measurements reveal that the tunable amount of intercalated Li(+) ion in the solid-state redox reaction between paramagnetic [W(V)(CN)8](3-) and diamagnetic [W(IV)(CN)8](4-) in the framework enables the electrochemical control of different magnetic regimes. While the initial ferromagnetic long-range ordering is irreversibly lost upon lithium insertion, electrochemical switching between paramagnetic and short-range ordering regimes can be achieved. PMID:27420412

  18. Intercalated hybrid graphite fiber composite

    NASA Technical Reports Server (NTRS)

    Gaier, James R. (Inventor)

    1993-01-01

    The invention is directed to a highly conductive lightweight hybrid material and methods of producing the same. The hybrid composite is obtained by weaving strands of a high strength carbon or graphite fiber into a fabric-like structure, depositing a layer of carbon onto the structure, heat treating the structure to graphitize the carbon layer, and intercalating the graphitic carbon layer structure. A laminate composite material useful for protection against lightning strikes comprises at least one layer of the hybrid material over at least one layer of high strength carbon or graphite fibers. The composite material of the present invention is compatible with matrix compounds, has a coefficient of thermal expansion which is the same as underlying fiber layers, and is resistant to galvanic corrosion in addition to being highly conductive. These materials are useful in the aerospace industry, in particular as lightning strike protection for airplanes.

  19. The intercalated cells of the amygdala.

    PubMed

    Millhouse, O E

    1986-05-01

    The intercalated cell groups, or massa intercalata, of the amygdala have been studied in rodent brains with Golgi methods. They also have been examined in gallocyanin-chromalum-, AChE-, and Timm-stained rat brains. The Golgi data indicate that the intercalated cells are not confined to a series of isolated cell clumps but form a neuronal net that covers the rostral half of the lateral-basolateral nuclear complex, stretches across a major portion of rostral amygdala, and continues rostrally beneath the anterior commissure. There are two general types of intercalated neuron--medium and large neurons. The medium intercalated neurons are more common. They have round to elongate somata, 9-18 microns in diameter, and round to bipolar dendritic trees, depending on their location. Most of the dendrites are spine-bearing, as are 20% of the somata. Their axons often have locally ramifying collaterals. The parent axons apparently terminate in either the lateral-basolateral or central nuclei and some of them appear to enter the external capsule. There is a unique medium intercalated neuron that has nearly spine-free, varicose dendrites and an axon that is typical of short axon (Golgi II) cells. There are two varieties of large intercalated neuron-spiny and aspiny. Most of them are aspiny, although they usually have a few spines scattered along their dendrites. Both varieties have elongate, sometimes round, somata that can be as much as 60 microns long. Their dendrites are long, thick, and have few branch points. Only the initial part of the large aspiny cell axon has been impregnated. The large spiny cell axons have several local collaterals; the destination of the parent axons is unknown. The intercalated cells occur along fiber bundles, which are probably afferent to them. The axons that travel among the intercalated cells give off short collaterals and boutons en passant. The sources of these fibers are not known. From the published experimental data, it is likely that they

  20. Stability of Bromine Intercalated Graphite Fibers

    NASA Technical Reports Server (NTRS)

    Gaier, J. R.

    1984-01-01

    Previous evidence suggested that bromine intercalation compounds of crystalline graphite spontaneously deintercalate when the bromine atmosphere is removed. However, results show that bromine intercalated P-100 graphite fibers are stable for long periods of time. They are stable under vacuum conditions, high humidity, and current densities up to 24,000 A/sq cm. They are thermally stable to 200 C, and at temperatures as high as 400 C still retain 80 percent of the conductivity gained by intercalation. At temperatures greater than 300 C, there is significant oxidative degradation of the fibers. The environmental stability shown by the bromine compound makes it a promising candidate for practical applications in aerospace technology.

  1. Effect of water intercalation on VOx layers in dodecylamine-intercalated vanadium oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Kweon, Hyocheon; Lee, Kyu Won; Lee, Eun Mo; Park, Jitae; Kim, I.-M.; Lee, Cheol Eui; Jung, G.; Gedanken, A.; Koltypin, Yu.

    2007-07-01

    Dodecylamine-intercalated vanadium oxide nanotubes were obtained by distinct synthesis processes. Water intercalation in the nanotube structure was identified in a marked manner by the distortion of the VOx layers in the x-ray diffraction patterns and enhanced V4+O absorption in the Fourier-transform infrared spectra. Our electron spin resonance measurements sensitively reflect changes in the microscopic structure and magnetic interactions introduced by the water intercalation in the vanadium oxide nanotubes.

  2. A method to remove intercalates from bromine and iodine intercalated carbon fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1993-01-01

    Upon exposure to room-temperature fluorine, intercalated carbon fibers (containing either bromine alone or iodine and bromine together) become heavier and less stable. For Amoco P-100 graphitized carbon fibers which were intercalated with 18 percent bromine by weight, 1 hr of fluorine exposure results in a large weight increase, but causes only a small decrease in thermal stability. More than l hr of fluorine exposure time results in small additional increases in fiber weight, but significant further decreases in fiber thermal stability. Such phenomena do not occur if the fluorine exposure is at 250 C. These observations suggest the mechanism that at room temperature, fluorine is absorbed quickly by the intercalated fibers and intercalated slowly into the fibers. Most of the original intercalates are replaced by fluorine in the process of fluorine intercalation. Under an inert environment, the bromine intercalated fibers are much more thermally stable. After 800 C vacuum heating for two weeks, the brominated fibers lost about 45 percent of their bromine, and their resistivity increased from 64 omega-cm to a range of 95 to 170 micro omega-cm. This is still much lower than the 300 micro omega-cm value for pristine P-100. For practical purposes, in order to preserve their thermal stability, brominated fibers need to be protected from exposure to fluorine at room temperature, or to any intercalate at a temperature where, upon direct contact to graphite, an intercalation compound can easily be formed.

  3. Organic intercalation of structure modified vermiculite.

    PubMed

    Wu, Nian; Wu, Limei; Liao, Libing; Lv, Guocheng

    2015-11-01

    The experiment used cationic surfactants of different chain lengths to intercalate structure modified vermiculites. The influences of structure modification, chain length and dosage of surfactants on the intercalation behavior of vermiculites were studied, and intercalation mechanism and features of interlayer chemical reactions were discussed. Results indicate that structure modified vermiculites with different layer charge have different intercalation behavior. The basal spacing of the organic intercalated modified vermiculite is the largest when acid concentration used in structure modification is 0.003 mol/L, and increases with increasing the chain length and dosage of the organics. Molecular dynamics simulation verifies that interlayer organics align almost parallel to structure layer of vermiculite, with alkyl chain stretching to the middle of interlayer space. -N(+) groups of the three surfactants locate above the leached [SiO4], which has stronger interaction with interlayer organic cations. Electrostatic force is the main interaction force between interlayer organics and structure layer of vermiculite, and then is Van der Waals force, no chemical bond formed. PMID:26196709

  4. Collecting duct intercalated cell function and regulation.

    PubMed

    Roy, Ankita; Al-bataineh, Mohammad M; Pastor-Soler, Núria M

    2015-02-01

    Intercalated cells are kidney tubule epithelial cells with important roles in the regulation of acid-base homeostasis. However, in recent years the understanding of the function of the intercalated cell has become greatly enhanced and has shaped a new model for how the distal segments of the kidney tubule integrate salt and water reabsorption, potassium homeostasis, and acid-base status. These cells appear in the late distal convoluted tubule or in the connecting segment, depending on the species. They are most abundant in the collecting duct, where they can be detected all the way from the cortex to the initial part of the inner medulla. Intercalated cells are interspersed among the more numerous segment-specific principal cells. There are three types of intercalated cells, each having distinct structures and expressing different ensembles of transport proteins that translate into very different functions in the processing of the urine. This review includes recent findings on how intercalated cells regulate their intracellular milieu and contribute to acid-base regulation and sodium, chloride, and potassium homeostasis, thus highlighting their potential role as targets for the treatment of hypertension. Their novel regulation by paracrine signals in the collecting duct is also discussed. Finally, this article addresses their role as part of the innate immune system of the kidney tubule. PMID:25632105

  5. Hydrogen intercalation under graphene on Ir(111)

    NASA Astrophysics Data System (ADS)

    Grånäs, Elin; Gerber, Timm; Schröder, Ulrike A.; Schulte, Karina; Andersen, Jesper N.; Michely, Thomas; Knudsen, Jan

    2016-09-01

    Using high resolution X-ray photoelectron spectroscopy and scanning tunneling microscopy we study the intercalation of hydrogen under graphene/Ir(111). The hydrogen intercalated graphene is characterized by a component in C 1s that is shifted -0.10 to -0.18 eV with respect to pristine graphene and a component in Ir 4f at 60.54 eV. The position of this Ir 4f component is identical to that of the Ir(111) surface layer with hydrogen atoms adsorbed, indicating that the atomic hydrogen adsorption site on bare Ir(111) and beneath graphene is the same. Based on co-existence of fully- and non-intercalated graphene, and the inability to intercalate a closed graphene film covering the entire Ir(111) surface, we conclude that hydrogen dissociatively adsorbs at bare Ir(111) patches, and subsequently diffuses rapidly under graphene. A likely entry point for the intercalating hydrogen atoms is identified to be where graphene crosses an underlying Ir(111) step.

  6. Intercalation of Aldehydes into Vanadyl Phosphate

    NASA Astrophysics Data System (ADS)

    Melánová, Klára; Beneš, Ludvík.; Zima, Vítězslav; Votinský, Jiří

    2001-02-01

    Intercalates of VOPO4 with several aliphatic aldehydes, benzaldehyde, and 4-methylbenzaldehyde were prepared and characterized by thermogravimetric analysis, X-ray diffractometry, and IR and UV-vis spectroscopies. Aliphatic aldehyde intercalates are unstable and the guests undergo aldol condensation and oxidation. The arrangement of the guest molecules in the interlayer space of the host is discussed. A part of aliphatic aldehydes is anchored to the host layers by coordination of their carbonyl oxygen to the vanadium atom; the rest is probably bonded by weak van der Waals forces. In the benzaldehyde and 4-methylbenzaldehyde intercalates, all guest molecules are coordinated to the vanadium atoms with their benzene rings perpendicular to the sheets of the host.

  7. Feasibility of intercalated graphite railgun armatures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Gooden, Clarence E.; Yashan, Doreen; Naud, Steven

    1990-01-01

    Graphite intercalation compounds may provide an excellent material for the fabrication of electro-magnetic railgun armatures. As a pulse of power is fed into the armature the intercalate could be excited into the plasma state around the edges of the armature, while the bulk of the current would be carried through the graphite block. Such an armature would have the desirable characteristics of both diffuse plasma armatures and bulk conduction armatures. In addition, the highly anisotropic nature of these materials could enable the electrical and thermal conductivity to be tailored to meet the specific requirements of electromagnetic railgun armatures. Preliminary investigations were performed in an attempt to determine the feasibility of using graphite intercalation compounds as railgun armatures. Issues of fabrication, resistivity, stability, and electrical current spreading are addressed for the case of highly oriented pyrolytic graphite.

  8. Demonstration of Einstein-Podolsky-Rosen Steering Using Single-Photon Path Entanglement and Displacement-Based Detection

    NASA Astrophysics Data System (ADS)

    Guerreiro, T.; Monteiro, F.; Martin, A.; Brask, J. B.; Vértesi, T.; Korzh, B.; Caloz, M.; Bussières, F.; Verma, V. B.; Lita, A. E.; Mirin, R. P.; Nam, S. W.; Marsilli, F.; Shaw, M. D.; Gisin, N.; Brunner, N.; Zbinden, H.; Thew, R. T.

    2016-08-01

    We demonstrate the violation of an Einstein-Podolsky-Rosen steering inequality developed for single-photon path entanglement with displacement-based detection. We use a high-rate source of heralded single-photon path-entangled states, combined with high-efficiency superconducting-based detectors, in a scheme that is free of any postselection and thus immune to the detection loophole. This result conclusively demonstrates single-photon entanglement in a one-sided device-independent scenario, and opens the way towards implementations of device-independent quantum technologies within the paradigm of path entanglement.

  9. Demonstration of Einstein-Podolsky-Rosen Steering Using Single-Photon Path Entanglement and Displacement-Based Detection.

    PubMed

    Guerreiro, T; Monteiro, F; Martin, A; Brask, J B; Vértesi, T; Korzh, B; Caloz, M; Bussières, F; Verma, V B; Lita, A E; Mirin, R P; Nam, S W; Marsilli, F; Shaw, M D; Gisin, N; Brunner, N; Zbinden, H; Thew, R T

    2016-08-12

    We demonstrate the violation of an Einstein-Podolsky-Rosen steering inequality developed for single-photon path entanglement with displacement-based detection. We use a high-rate source of heralded single-photon path-entangled states, combined with high-efficiency superconducting-based detectors, in a scheme that is free of any postselection and thus immune to the detection loophole. This result conclusively demonstrates single-photon entanglement in a one-sided device-independent scenario, and opens the way towards implementations of device-independent quantum technologies within the paradigm of path entanglement. PMID:27563941

  10. Metal Ion Intercalated graphitic as Transparent Electrodes

    NASA Astrophysics Data System (ADS)

    Wan, Jiayu; Bao, Wenzhong; Gu, Feng; Fuhrer, Michael; Hu, Liangbing; UMD Team

    To best utilize the performance of graphene based transparent electrodes, we novelized Li-ion intercalation in graphene, and achieved highest performance of carbon based transparent electrodes. Transmission as high as 91.7% with a sheet resistance of 3.0 ohm/sq is achieved for 19-layer LiC6, significantly higher than any other continuous transparent electrodes. The unconventional modification of ultrathin graphite optoelectronic properties is explained by the suppression of interband optical transitions and a small intraband Drude conductivity near the interband edge. To achieve low cost, large scale graphene-based transparent electrodes, we further developed Na-ion intercalated printed reduced graphene oxide (RGO) film. The larger layer-layer distance of RGO allows Na-ion intercalation, leading to simultaneously much higher DC conductivity and higher optical transmittance. Typical increase of transmittance from 36% to 79% and decrease of sheet resistance from 83 kohms/sq to 311 ohms/sq in the printed network was observed. This study demonstrated the great potential of metal-ion intercalation to improve the performance of graphene-based materials for transparent conductor applications.

  11. Hexacyanoferrate-intercalated nickel zinc hydroxy double salts

    NASA Astrophysics Data System (ADS)

    Rajamathi, Jacqueline T.; Raviraj, N. H.; Ahmed, Mohammed F.; Rajamathi, Michael

    2009-12-01

    When anionic clay like nickel zinc hydroxyacetate was subjected to anion exchange reaction with either hexacyanoferrate(II) or hexacyanoferrate(III) ions, the complex anion intercalation was accompanied by auto redox reactions. In both the cases a mixture of hexacyanoferrate(II) and hexacyanoferrate(III) ions was found to be intercalated in the anionic clay. The mixed anion intercalated anionic clays could be oxidized by hydrogen peroxide to get pure hexacyanoferrate(III) intercalated anionic clay. Thermal decomposition of the intercalated anionic clays yields mixed oxides of Ni, Zn and Fe.

  12. Mg intercalation into Ti2C building block

    NASA Astrophysics Data System (ADS)

    Yu, Xue-fang; Cheng, Jianbo; Liu, Zhenbo; Li, Qingzhong; Li, Wenzuo; Yang, Xin; Xiao, Bo

    2015-06-01

    Generally, intercalation occurs when foreign atoms intercalate into multi-layer structures, while adsorption occurs when foreign atoms interact with monolayer structures or surfaces. We performed an investigation on the Mg intercalation into Ti2C building block (MXene) from first-principles simulation. We found that Mg can favorably intercalate into MXene, forming the stable compound Ti2MgC, which corresponds to the stage I in the Li intercalation into graphite. Based on the evaluation of the average cell potential and the energy barrier of Mg diffusion for the most energetically stable structure, our results suggest that Ti2MgC is a potential anode for Mg ion batteries.

  13. Assessment of Soil-Structure Interaction in Seismic Bridge Pier Analysis Using Force and Displacement Based Approaches

    NASA Astrophysics Data System (ADS)

    Singh, R. N. P.; Vinayak, Hemant Kumar

    2015-11-01

    The seismic analysis carried out assuming foundation to be perfectly rigid and bonded to the soil underneath is far from truth and therefore, the soil-structure interaction effect on the dynamic behavior of the bridge pier should be considered. The assessment of soil-structure effect on the design force generated has been estimated using Force based, Capacity Spectrum and Direct Displacement based methods considering fixed and flexible foundations. For this purpose a single cantilever bridge pier of constant diameter with varying heights has been considered for the analysis in different type of soils and earthquake zones. The study has revealed that soil-Structure Interaction index is negative in some cases, especially in soft soil, implying base shear demand being greater than that of fixed base contrary to the traditional views.

  14. Guided Discoveries.

    ERIC Educational Resources Information Center

    Ehrlich, Amos

    1991-01-01

    Presented are four mathematical discoveries made by students on an arithmetical function using the Fibonacci sequence. Discussed is the nature of the role of the teacher in directing the students' discovery activities. (KR)

  15. Discovery Systems

    NASA Technical Reports Server (NTRS)

    Pell, Barney

    2003-01-01

    A viewgraph presentation on NASA's Discovery Systems Project is given. The topics of discussion include: 1) NASA's Computing Information and Communications Technology Program; 2) Discovery Systems Program; and 3) Ideas for Information Integration Using the Web.

  16. Phosphate-stabilized Lithium intercalation compounds

    SciTech Connect

    Richardson, Thomas J.

    2002-07-22

    Four manganese and iron phosphates with alluaudite or fillowite structures have been prepared by solid state reactions: Na2FeMn2(PO4)3, LiNaFeMn2(PO4)3, NaFe3(PO4)3, and Na2Mn3(PO4)3. LixNa2-xFeMn2(PO4)3 with x close to 2 was prepared from Na2FeMn2(PO4)3 by molten salt ion exchange. These materials are similar in stoichiometry to the phospho-olivines LiFe(Mn)PO4, but have a more complex structure that can accommodate mixed transition metal oxidation states. They are of interest as candidates for lithium battery cathodes because of their somewhat higher electronic conductivity, high intercalant ion mobility, and ease of preparation. Their performance as intercalation electrodes in non-aqueous lithium cells was, however, poor.

  17. Monte Carlo simulation of intercalated carbon nanotubes.

    PubMed

    Mykhailenko, Oleksiy; Matsui, Denis; Prylutskyy, Yuriy; Le Normand, Francois; Eklund, Peter; Scharff, Peter

    2007-01-01

    Monte Carlo simulations of the single- and double-walled carbon nanotubes (CNT) intercalated with different metals have been carried out. The interrelation between the length of a CNT, the number and type of metal atoms has also been established. This research is aimed at studying intercalated systems based on CNTs and d-metals such as Fe and Co. Factors influencing the stability of these composites have been determined theoretically by the Monte Carlo method with the Tersoff potential. The modeling of CNTs intercalated with metals by the Monte Carlo method has proved that there is a correlation between the length of a CNT and the number of endo-atoms of specific type. Thus, in the case of a metallic CNT (9,0) with length 17 bands (3.60 nm), in contrast to Co atoms, Fe atoms are extruded out of the CNT if the number of atoms in the CNT is not less than eight. Thus, this paper shows that a CNT of a certain size can be intercalated with no more than eight Fe atoms. The systems investigated are stabilized by coordination of 3d-atoms close to the CNT wall with a radius-vector of (0.18-0.20) nm. Another characteristic feature is that, within the temperature range of (400-700) K, small systems exhibit ground-state stabilization which is not characteristic of the higher ones. The behavior of Fe and Co endo-atoms between the walls of a double-walled carbon nanotube (DW CNT) is explained by a dominating van der Waals interaction between the Co atoms themselves, which is not true for the Fe atoms. PMID:17033783

  18. EMI Shields made from intercalated graphite composites

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Terry, Jennifer

    1995-01-01

    Electromagnetic interference (EMI) shielding typically makes up about twenty percent of the mass of a spacecraft power system. Graphite fiber/polymer composites have significantly lower densities and higher strengths than aluminum, the present material of choice for EMI shields, but they lack the electrical conductivity that enables acceptable shielding effectiveness. Bromine intercalated pitch-based graphite/epoxy composites have conductivities fifty times higher than conventional structural graphite fibers. Calculations are presented which indicate that EMI shields made from such composites can have sufficient shielding at less than 20% of the mass of conventional aluminum shields. EMI shields provide many functions other than EMI shielding including physical protection, thermal management, and shielding from ionizing radiation. Intercalated graphite composites perform well in these areas also. Mechanically, they have much higher specific strength and modulus than aluminum. They also have shorter half thicknesses for x-rays and gamma radiation than aluminum. Thermally, they distribute infra-red radiation by absorbing and re-radiating it rather than concentrating it by reflection as aluminum does. The prospects for intercalated graphite fiber/polymer composites for EMI shielding are encouraging.

  19. Superconducting graphite intercalation compounds with calcium

    NASA Astrophysics Data System (ADS)

    Emery, N.; Hérold, C.; Marêché, J.-F.; Lagrange, P.; Bellouard, C.; Lamura, G.; Di Gennaro, E.; Andreone, A.

    2008-04-01

    In the graphite-lithium-calcium system, four well-defined intercalation compounds were synthesised. Two of them, CaC 6 and Li 3Ca 2C 6, exhibit superconducting properties at 11.5 K and 11.15 K, respectively, the highest critical temperatures among those of graphite intercalation compounds. The samples are synthesised using a liquid-solid method allowing the preparation of pure bulk samples, auspicious for crystallographic and magnetic measurements. The crystal structure of CaC 6 was entirely specified; this compound crystallises in the R-3 m space group. The two-dimensional unit cell of Li 3Ca 2C 6 is hexagonal and commensurate with that of graphite and the intercalated sheets, very rich in metal, are seven-layered. The magnetic properties of these phases were studied with an applied field parallel and perpendicular to the graphene sheets. In both cases the magnetic phase diagram indicates that these compounds are type II superconducting materials slightly anisotropic in spite of their lamellar structure. In the case of CaC 6, in-plane magnetic penetration depth measurements show a clear exponential behaviour at low temperatures, consistent with an s-wave symmetry of the gap function, well fitted by the standard BCS theory in the dirty limit.

  20. Pristine and intercalated transition metal dichalcogenide superconductors

    NASA Astrophysics Data System (ADS)

    Klemm, Richard A.

    2015-07-01

    Transition metal dichalcogenides (TMDs) are quasi-two-dimensional layered compounds that exhibit strongly competing effects of charge-density wave (CDW) formation and superconductivity (SC). The weak van der Waals interlayer bonding between hexagonal layers of octahedral or trigonal prismatic TMD building blocks allows many polytypes to form. In the single layer 1 T polytype materials, one or more CDW states can form, but the pristine TMDs are not superconducting. The 2 H polytypes have two or more Fermi surfaces and saddle bands, allowing for dual orderings, which can be coexisting CDW and SC orderings, two SC gaps as in MgB2, two CDW gaps, and possibly even pseudogaps above the onset TCDW s of CDW orderings. Higher order polytypes allow for multiple CDW gaps and at least one superconducting gap. The CDW transitions TCDW s usually greatly exceed the superconducting transitions at their low Tc values, their orbital order parameters (OPs) are generally highly anisotropic and can even contain nodes, and the SC OPs can be greatly affected by their simultaneous presence. The properties of the CDWs ubiquitously seen in TMDs are remarkably similar to those of the pseudogaps seen in the high-Tc cuprates. In 2H-NbSe2, for example, the CDW renders its general s-wave SC OP orbital symmetry to be highly anisotropic and strongly reduces its Josephson coupling strength (IcRn) with the conventional SC, Pb. Hence, the pristine TMDs are highly "unconventional" in comparison with Pb, but are much more "conventional" than are the ferromagnetic superconductors such as URhGe. Applied pressure and intercalation generally suppress the TMD CDWs, allowing for enhanced SC formation, even in the 1 T polytype materials. The misfit intercalation compound (LaSe)1.14(NbSe2) and many 2 H -TMDs intercalated with organic Lewis base molecules, such as TaS2(pyridine)1/2, have completely incoherent c-axis transport, dimensional-crossover effects, and behave as stacks of intrinsic Josephson junctions

  1. Intercalation compounds and electrodes for batteries

    DOEpatents

    Chiang, Yet-Ming; Sadoway, Donald R.; Jang, Young-Il; Huang, Biyan

    2004-09-07

    This invention concerns intercalation compounds and in particular lithium intercalation compounds which have improved properties for use in batteries. Compositions of the invention include particulate metal oxide material having particles of multicomponent metal oxide, each including an oxide core of at least first and second metals in a first ratio, and each including a surface coating of metal oxide or hydroxide that does not include the first and second metals in the first ratio formed by segregation of at least one of the first and second metals from the core. The core may preferably comprise Li.sub.x M.sub.y N.sub.z O.sub.2 wherein M and N are metal atom or main group elements, x, y and z are numbers from about 0 to about 1 and y and z are such that a formal charge on M.sub.y N.sub.z portion of the compound is (4-x), and having a charging voltage of at least about 2.5V. The invention may also be characterized as a multicomponent oxide microstructure usable as a lithium intercalation material including a multiphase oxide core and a surface layer of one material, which is a component of the multiphase oxide core, that protects the underlying intercalation material from chemical dissolution or reaction. In a particular preferred example the multicomponent oxide may be an aluminum-doped lithium manganese oxide composition. Such aluminum-doped lithium manganese oxide compositions, having an orthorhombic structure, also form a part of the invention. In addition, the invention includes articles, particularly electrodes, for batteries formed from the compositions of the invention, and batteries including such electrodes. The invention further relates to a composite intercalation material comprising at least two compounds in which at least one compound has an orthorhombic structure Li.sub.x Al.sub.y Mn.sub.1-y O.sub.2, where y is nonzero, or a mixture of orthorhombic and monoclinic Li.sub.x Al.sub.y Mn.sub.1-y O.sub.2.

  2. Synthesis and stability of Br2, ICl and IBr intercalated pitch-based graphite fibers

    NASA Technical Reports Server (NTRS)

    Wessbecher, Dorothy E.; Forsman, William C.; Gaier, James R.

    1988-01-01

    The intercalation of halogens in pitch-based fiber is studied as well as the stability of the resultant intercalation compounds. It is found that IBr intercalates P-100 to yield a high-sigma GIC with attractive stability properties. During ICl intercalation, the presence of O2 interferes with the reaction and necessitates a higher threshold pressure for intercalation.

  3. Physics and chemistry of MoS2 intercalation compounds

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Somoano, R. B.

    1977-01-01

    An investigation is made of the physics and chemistry of MoS2 intercalation compounds. These compounds may be separated into two groups according to their stoichiometry, structure and superconducting properties. The first group consists of Na, Ca, and Sr intercalates, and the second group consists of K, Rb, and Cs intercalates. Particular attention is given to the structure of the electronic energy band and to the normal state and superconducting properties of these compounds.

  4. Tuning frictions between graphene layers via Li ion intercalation

    NASA Astrophysics Data System (ADS)

    Lu, Aijiang; Wan, Jiayu; Li, Teng; Hu, Liangbing; Univerisyt of Maryland, College Park Team

    Graphite intercalated with Li ions are widely studied and applied in Li ion batteries. It was revealed in experiments that, the Li ion intercalation leads to a phase transition of the graphite with about 10% volume expansion. The increased interlayer distance should contribute to decrease the frictions between the grahene layers, but the Li ion intercalation would take an opposite effect. In order to show the total effect of the Li ion interalation, we studied the frictions between graphene layers with and without lithiation, based on density functional theory (DFT). In a sandwich-like model, slipping of the middle sheet of the graphene was simulated. Displacements between layers were fixed and the other parts were relaxed, thus the energies were record to estimate the energy barriers accordingly. We found that the frictions between the graphene layers with the Li ion intercalation are higher than those without intercalation. The energy barrier appears correlated with the concentration of the intercalated ions. As the atomic ratio between lithium and carbon increases from 0 (no intercalation) to 1:6, the energy barriers increase from 0.01 eV/atom to 0.05 eV/atom or so. Such an interesting result indicates that, just via ion intercalation, we can effectively tune the friction between graphene layers. Tuning frictions between graphene layers via Li ion intercalation.

  5. Intercalation of Anionic Oxalato Complexes into Layered Double Hydroxides

    NASA Astrophysics Data System (ADS)

    Prevot, V.; Forano, C.; Besse, J. P.

    2000-09-01

    Intercalation compounds of layered double hydroxide (LDH), MII1-xMIIIx(OH)2Ax/y·nH2O (with MII=Zn, Cu and MIII=Al, Cr, Ga), with oxalato complexes of aluminium, gallium, chromium, copper, and beryllium, were obtained via anion-exchange processes. Powder X-ray diffraction indicated that the intercalation reactions were successful. The basal spacings measured after intercalation are near 0.98±0.02 nm, whatever the host matrix composition. Studies by FTIR spectroscopy confirmed the intercalation of the oxalato complex, too. In order to study the thermal decomposition of the exchanged products, TGA-coupled mass spectrometry was performed.

  6. Superconductivity in Li{sub 3}Ca{sub 2}C{sub 6} intercalated graphite

    SciTech Connect

    Emery, Nicolas; Herold, Claire . E-mail: Claire.Herold@lcsm.uhp-nancy.fr; Mareche, Jean-Francois; Bellouard, Christine; Loupias, Genevieve; Lagrange, Philippe

    2006-04-15

    In this paper, we report the discovery of superconductivity in Li{sub 3}Ca{sub 2}C{sub 6}. Several graphite intercalation compounds (GICs) with electron donors, are well known as superconductors [T. Enoki, S. Masatsugu, E. Morinobu, Graphite Intercalation Compounds and Applications, Oxford University Press, Oxford, 2003]. It is probably not astonishing, since it is generally admitted that low dimensionality promotes high superconducting transition temperatures. Superconductivity is lacking in pristine graphite, but after charging the graphene planes by intercalation, its electronic properties change considerably and superconducting behaviour can appear. Li{sub 3}Ca{sub 2}C{sub 6} is a ternary GIC [S. Pruvost, C. Herold, A. Herold, P. Lagrange, Eur. J. Inorg. Chem. 8 (2004) 1661-1667], for which the intercalated sheets are very thick and poly layered (five lithium layers and two calcium ones). It contains a great amount of metal (five metallic atoms for six carbon ones). Its critical temperature of 11.15 K is very close to that of CaC{sub 6} GIC [T.E. Weller, M. Ellerby, S.S. Saxena, R.P. Smith, N.T. Skipper, Nat. Phys. 1 (2005) 39-41; N. Emery, C. Herold, M. d'Astuto, V. Garcia, Ch. Bellin, J.F. Mareche, P. Lagrange, G. Loupias, Phys. Rev. Lett. 95 (2005) 087003] (11.5 K). Both CaC{sub 6} and Li{sub 3}Ca{sub 2}C{sub 6} GICs possess currently the highest transition temperatures among all the GICs.

  7. Intercalation of water into lithium. beta. -alumina

    SciTech Connect

    Dudney, N J; Bates, J B; Wang, J C; Brown, G M; Larson, B C; Engstrom, H

    1981-01-01

    Infrared absorption, neutron diffraction and weight loss techniques have been used to investigate the hydration of single crystals of Li ..beta..-alumina. The hydration is a reversible intercalation reaction. Up to approximately two water molecules per formula unit can penetrate the conduction plane. Other protonated species are formed from the dissociation of the molecular water. The rate of hydration is controlled by the diffusion of water in the conduction plane. A likely diffusion mechanism requires dissociation of the water and an interstitialcy motion of the oxygen.

  8. Lithium intercalation in porous carbon anodes

    SciTech Connect

    Tran, T.D.; Pekala, R.W.; Mayer, S.T.

    1994-11-23

    Carbon foams derived from the phase separation of polyacrylonitrile/solvent mixtures were investigated as lithium intercalation anodes for rechargeable lithium-ion batteries. The carbon foams have a bulk density of 0.35--0.5 g/cm{sup 3}, low surface area (< 50 m{sup 2}/g), and an average cell size of 5--10 {mu}m. Polyacrylonitrile-based carbon foams doped with phosphoric acid had capacity as high as 450 mAh/g. Carbon capacity increased with increasing phosphoric acid concentration in the doping solution. The doped porous carbon anodes exhibited good cyclability and excellent coulombic efficiency.

  9. Intercalation processes of copper complexes in DNA

    PubMed Central

    Galindo-Murillo, Rodrigo; García-Ramos, Juan Carlos; Ruiz-Azuara, Lena; Cheatham, Thomas E.; Cortés-Guzmán, Fernando

    2015-01-01

    The family of anticancer complexes that include the transition metal copper known as Casiopeínas® shows promising results. Two of these complexes are currently in clinical trials. The interaction of these compounds with DNA has been observed experimentally and several hypotheses regarding the mechanism of action have been developed, and these include the generation of reactive oxygen species, phosphate hydrolysis and/or base-pair intercalation. To advance in the understanding on how these ligands interact with DNA, we present a molecular dynamics study of 21 Casiopeínas with a DNA dodecamer using 10 μs of simulation time for each compound. All the complexes were manually inserted into the minor groove as the starting point of the simulations. The binding energy of each complex and the observed representative type of interaction between the ligand and the DNA is reported. With this extended sampling time, we found that four of the compounds spontaneously flipped open a base pair and moved inside the resulting cavity and four compounds formed stacking interactions with the terminal base pairs. The complexes that formed the intercalation pocket led to more stable interactions. PMID:25958394

  10. Lithium intercalation in porous carbon electrodes

    SciTech Connect

    Tran, T.D.; Feikert, J.; Pekala, R.W.

    1995-04-01

    Carbons derived from the phase separation of polyacrylonitrile/solvent mixtures were investigated as lithium intercalation anodes for rechargeable lithium-ion batteries. The carbon electrodes have a bulk density of 0.35-0.5 g/cm{sup 3}, relatively low surface areas (< 10 m{sup 2}/g), and micron-size cells. Pyrolysis temperature influences the reversible lithium intercalation and the irreversible capacity (associated with the formation of the passivating layer). Carbon electrodes pyrolyzed at 600{degrees}C have first-cycle capacity as high as 550 mAh/g as well as large irreversible capacity, 440 mAh/g. Electrodes prepared at 1050{degrees}C have reversible capacities around 270 mAh/g with relatively lower capacity losses (120 mAh/g). Doping the organic precursors with phosphoric acid, prior to pyrolysis at 1050{degrees}C, leads to carbon electrodes with reversible capacities as high as 450 mAh/g. The capacity of doped carbon increased with increasing phosphorus concentration in the samples. The doped carbon anodes exhibited good cycleability and excellent coulombic efficiency. The electrochemical performance is related to morphology, chemical composition, and local structural order.

  11. Plasmon characteristics in stage-1 graphene intercalation compounds

    NASA Astrophysics Data System (ADS)

    Acharya, Sidharth; Sharma, Raman

    2015-05-01

    We report the Plasmon characteristics in stage-1 graphene intercalation compounds (GIC's), using the massless Dirac fermion (MDF) gas approximation. With the discussion of the weak and the strong c-axis coupling at graphene-intercalant hetrojunction plasmon characteristics of GIC's are predicted. We have found a reasonable agreement between our results and the experimental results of Ritsko and Rice.

  12. Intercalation studies of zinc hydroxide chloride: Ammonia and amino acids

    NASA Astrophysics Data System (ADS)

    Arízaga, Gregorio Guadalupe Carbajal

    2012-01-01

    Zinc hydroxide chloride (ZHC) is a layered hydroxide salt with formula Zn5(OH)8Cl2·2H2O. It was tested as intercalation matrix for the first time and results were compared with intercalation products of the well-known zinc hydroxide nitrate and a Zn/Al layered double hydroxide. Ammonia was intercalated into ZHC, while no significant intercalation occurred in ZHN. Aspartic acid intercalation was only achieved by co-precipitation at pH=10 with ZHC and pH=8 with zinc hydroxide nitrate. Higher pH resistance in ZHC favored total deprotonation of both carboxylic groups of the Asp molecule. ZHC conferred more thermal protection against Asp combustion presenting exothermic peaks even at 452 °C while the exothermic event in ZHN was 366 °C and in the LDH at 276 °C.

  13. Superconductivity in the alkali metal intercalates of molybdenum disulphide

    NASA Technical Reports Server (NTRS)

    Somoano, R. B.; Hadek, V.; Rembaum, A.

    1972-01-01

    The complete series of alkali metals, lithium through cesium, have been intercalated into molybdenum disulphide, using both the liquid ammonia and vapor techniques. All the intercalates with the exception of lithium yielded full superconducting transitions with onset temperatures of 6 K for AxMoS2(Ax=K,Rb,Cs) and 4 K for BxMoS2(Bx=Li,Na). The superconducting transition for lithium was incomplete down to 1.5 K. Stoichiometries and unit cell parameters have been determined for the intercalation compounds. Both rhombohedral and hexagonal polymorphs of MoS2 have been intercalated and found to exhibit the same superconductivity behavior. The nature of the extraneous superconducting transition of some intercalated samples on exposure to air was elucidated.

  14. Quasi-freestanding graphene on Ni(111) by Cs intercalation.

    PubMed

    Alattas, M; Schwingenschlögl, U

    2016-01-01

    A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. Cs intercalation between graphene and Ni(111) therefore is investigated using density functional theory, incorporating van der Waals corrections. It is known that direct contact between graphene and Ni(111) perturbs the Dirac states. We find that Cs intercalation restores the linear dispersion characteristic of Dirac fermions, which agrees with experiments, but the Dirac cone is shifted to lower energy, i.e., the graphene sheet is n-doped. Cs intercalation therefore decouples the graphene sheet from the substrate except for a charge transfer. On the other hand, the spin polarization of Ni(111) does not extend through the intercalated atoms to the graphene sheet, for which we find virtually spin-degeneracy. PMID:27225324

  15. Quasi-freestanding graphene on Ni(111) by Cs intercalation

    NASA Astrophysics Data System (ADS)

    Alattas, M.; Schwingenschlögl, U.

    2016-05-01

    A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. Cs intercalation between graphene and Ni(111) therefore is investigated using density functional theory, incorporating van der Waals corrections. It is known that direct contact between graphene and Ni(111) perturbs the Dirac states. We find that Cs intercalation restores the linear dispersion characteristic of Dirac fermions, which agrees with experiments, but the Dirac cone is shifted to lower energy, i.e., the graphene sheet is n-doped. Cs intercalation therefore decouples the graphene sheet from the substrate except for a charge transfer. On the other hand, the spin polarization of Ni(111) does not extend through the intercalated atoms to the graphene sheet, for which we find virtually spin-degeneracy.

  16. Metal intercalation-induced selective adatom mass transport on graphene

    DOE PAGESBeta

    Liu, Xiaojie; Wang, Cai -Zhuang; Hupalo, Myron; Lin, Hai -Qing; Ho, Kai -Ming; Thiel, Patricia A.; Tringides, Michael C.

    2016-03-29

    Recent experiments indicate that metal intercalation is a very effective method to manipulate the graphene-adatom interaction and control metal nanostructure formation on graphene. A key question is mass transport, i.e., how atoms deposited uniformly on graphene populate different areas depending on the local intercalation. Using first-principles calculations, we show that partially intercalated graphene, with a mixture of intercalated and pristine areas, can induce an alternating electric field because of the spatial variations in electron doping, and thus, an oscillatory electrostatic potential. As a result, this alternating field can change normal stochastic adatom diffusion to biased diffusion, leading to selective massmore » transport and consequent nucleation, on either the intercalated or pristine areas, depending on the charge state of the adatoms.« less

  17. Structural analysis of Li-intercalated hexagonal boron nitride

    SciTech Connect

    Sumiyoshi, A.; Hyodo, H.; Kimura, K.

    2012-03-15

    A structural investigation of Li-intercalated hexagonal boron nitride (Li-h-BNIC) was performed by synchrotron powder X-ray diffraction analysis and transmission electron microscopy. The host BN framework of Li-h-BNIC was expanded by Li-intercalation. The intralayer B-N bond length was increased by 2.48(1)% and the interlayer distance was expanded by 12.86(1)%. No superlattice structure of intercalated Li was observed. - Graphical abstract: XRD pattern fitting of the sample and schematic view of host h-BN lattice. Highlights: Black-Right-Pointing-Pointer Li-intercalated h-BN was investigated by synchrotron radiation powder XRD. Black-Right-Pointing-Pointer Lattice parameter of host h-BN lattice was increased by intercalation. Black-Right-Pointing-Pointer Increase ratio of B-N bond length was considerably larger than those of Li GICs.

  18. Homogeneity of pristine and bromine intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, J. R.; Marino, D.

    1985-01-01

    Wide variations in the resistivity of intercalated graphite fibers and to use these materials for electrical applications, their bulk properties must be established. The homogeneity of the diameter, the resistivity, and the mass density of 50 graphite fibers, before and after bromine intercalation was measured. Upon intercalation the diameter was found to expand by about 5%, the resistivity to decrease by a factor of five, and the density to increase by about 6%. Each individual fiber was found to have uniform diameter and resistivity over macroscopic regions for lengths as long as 7 cm. The ratio of pristine to intercalated resistivity increases as the pristine fiber diameter increases at a rate of 0.16 micron, but decreases with the increasing ratio of intercalated diameter to pristine diameter at a rate of 0.08.

  19. Intercalation of solid hydrogen into graphite under pressures

    NASA Astrophysics Data System (ADS)

    Lim, Jinhyuk; Yoo, Choong-Shik

    2016-08-01

    We present the Raman spectral evidence of pressure-induced intercalation of solid hydrogen into graphite to 60 GPa. The intercalation is evident by the emergence of two characteristic Raman bands of hydrogen (νo1 and νo2), which appear upon the solidification of hydrogen and disappear as all sp2-hybridized graphitic carbons convert to sp3-hybridized hexagonal diamond at 57 GPa. The νo1 and νo2 frequencies of intercalated hydrogen, 4250 and 4270 cm-1 at 10 GPa, are substantially higher than the νo of bulk hydrogen, 4228 cm-1 at the same pressure, indicating the presence of strong repulsive interactions between intercalated hydrogen molecules and graphite layers and, thereby, strong internal chemical pressures. Based on the spectral blue shift of intercalated hydrogen vibrons, we estimate the internal pressure to be ˜1 GPa at 10 GPa and ˜10 GPa at 50 GPa.

  20. Quasi-freestanding graphene on Ni(111) by Cs intercalation

    PubMed Central

    Alattas, M.; Schwingenschlögl, U.

    2016-01-01

    A possible approach to achieve quasi-freestanding graphene on a substrate for technological purpose is the intercalation of alkali metal atoms. Cs intercalation between graphene and Ni(111) therefore is investigated using density functional theory, incorporating van der Waals corrections. It is known that direct contact between graphene and Ni(111) perturbs the Dirac states. We find that Cs intercalation restores the linear dispersion characteristic of Dirac fermions, which agrees with experiments, but the Dirac cone is shifted to lower energy, i.e., the graphene sheet is n-doped. Cs intercalation therefore decouples the graphene sheet from the substrate except for a charge transfer. On the other hand, the spin polarization of Ni(111) does not extend through the intercalated atoms to the graphene sheet, for which we find virtually spin-degeneracy. PMID:27225324

  1. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-01

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg-Al and Mg-Fe layered double hydroxides (LDHs) have been synthesized by the calcination-rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV-vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO32- solutions imply that Mg3Al-VC LDH is a better controlled release system than Mg3Fe-VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO32- solution.

  2. Intercalation and controlled release properties of vitamin C intercalated layered double hydroxide

    SciTech Connect

    Gao, Xiaorui; Lei, Lixu; O'Hare, Dermot; Xie, Juan; Gao, Pengran; Chang, Tao

    2013-07-15

    Two drug-inorganic composites involving vitamin C (VC) intercalated in Mg–Al and Mg–Fe layered double hydroxides (LDHs) have been synthesized by the calcination–rehydration (reconstruction) method. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV–vis absorption spectroscopy indicate a successful intercalation of VC into the interlayer galleries of the LDH host. Studies of VC release from the LDHs in deionised water and in aqueous CO{sub 3}{sup 2−} solutions imply that Mg{sub 3}Al–VC LDH is a better controlled release system than Mg{sub 3}Fe–VC LDH. Analysis of the release profiles using a number of kinetic models suggests a solution-dependent release mechanism, and a diffusion-controlled deintercalation mechanism in deionised water, but an ion exchange process in CO{sub 3}{sup 2−} solution. - Graphical abstract: Vitamin C anions have been intercalated in the interlayer space of layered double hydroxide and released in CO{sub 3}{sup 2−} solution and deionised water. - Highlights: • Vitamin C intercalated Mg–Al and Mg–Fe layered double hydroxides were prepared. • Release property of vitamin C in aqueous CO{sub 3}{sup 2−} solution is better. • Avrami-Erofe’ev and first-order models provide better fit for release results. • Diffusion-controlled and ion exchange processes occur in deionised water. • An ion exchange process occurs in CO{sub 3}{sup 2−} solution.

  3. Alkali-metal intercalation in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Béguin, F.; Duclaux, L.; Méténier, K.; Frackowiak, E.; Salvetat, J. P.; Conard, J.; Bonnamy, S.; Lauginie, P.

    1999-09-01

    We report on successful intercalation of multiwall (MWNT) and single wall (SWNT) carbon nanotubes with alkali metals by electrochemical and vapor phase reactions. A LiC10 compound was produced by full electrochemical reduction of MWNT. KC8 and CsC8-MWNT first stage derivatives were synthesized in conditions of alkali vapor saturation. Their identity periods and the 2×2 R 0° alkali superlattice are comparable to their parent graphite compounds. The dysonian shape of KC8 EPR line and the temperature-independent Pauli susceptibility are both characteristic of a metallic behavior, which was confirmed by 13C NMR anisotropic shifts. Exposure of SWNT bundles to alkali vapor led to an increase of the pristine triangular lattice from 1.67 nm to 1.85 nm and 1.87 nm for potassium and rubidium, respectively.

  4. Fabricating graphene devices from graphite intercalation compounds

    NASA Astrophysics Data System (ADS)

    Yagi, Ryuta; Shimomura, Midori; Tahara, Fumiya; Fukada, Seiya

    2013-03-01

    We report a method of making few-layer graphene flakes by mechanically exfoliating SbCl5-graphite intercalation compounds (GICS). The number of exfoliated graphene flakes had a peculiar distribution relevant to the stage structure of GICs. The carrier doping of the few-layer graphene flakes was about two orders of magnitude smaller than that expected from the stoichiometry of the GICs. The measured electric mobility was comparable to that made from pristine graphite. The EPMA measurement showed that inhomogeneous distribution of dopant near the surface of GIC was responsible for obtaining the virtually undoped graphene. Deintercalation of dopant would expand interlayer distance of each graphene layer, and thereby layer-number of exfoliated graphene depended stage number of GIC.

  5. Intercalation compounds involving inorganic layered structures

    PubMed

    Constantino; Barbosa; Bizeto; Dias

    2000-01-01

    Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts. PMID:10932103

  6. Intercalation of hexagonal boron nitride with potassium

    SciTech Connect

    Doll, G.L.; Speck, J.S.; Dresselhaus, G.; Dresselhaus, M.S. ); Nakamura, K.; Tanuma, S.

    1989-09-15

    We have performed photoluminescence, photoexcitation, and transmission electron microscopy measurements on boron nitride films grown by chemical vapor deposition and later reacted with potassium. After reaction, the potassium atoms were found to intercalate the BN host and to form a (2{times}2){ital R}0{degree} in-plane structure which is commensurate with the pristine BN lattice. Optical transitions with {similar to}2.7 eV onsets were found to occur within the {similar to}5-eV BN band gap and have been interpreted as {Gamma}-point transitions between the K(4{ital s}) band and the BN(2{ital p}) bands. The absence of an appreciable shift in the {ital E}{sub 2{ital g}{sub 2}} phonon frequency of the pristine and reacted films suggests that the charge transfer between the K and BN bands is very small.

  7. Carbonaceous materials as lithium intercalation anodes

    SciTech Connect

    Tran, T.D.; Feikert, J.H.; Mayer, S.T.; Song, X.; Kinoshita, K.

    1994-10-01

    Commercial and polymer-derived carbonaceous materials were examined as lithium intercalation anodes in propylene carbonate (pyrolysis < 1350C, carbons) and ethylene carbonate/dimethyl carbonate (graphites) electrolytes. The reversible capacity (180--355 mAh/g) and the irreversible capacity loss (15--200 % based on reversible capacity) depend on the type of binder, carbon type, morphology, and phosphorus doping concentration. A carbon-based binder was chosen for electrode fabrication, producing mechanically and chemically stable electrodes and reproducible results. Several types of graphites had capacity approaching LiC{sub 6}. Petroleum fuel green cokes doped with phosphorous gave more than a 20 % increase in capacity compared to undoped samples. Electrochemical characteristics are related to SEM, TEM, XRD and BET measurements.

  8. Influence of polymeric binder on the stability and intercalation/de-intercalation behaviour of graphite electrodes in non-aqueous solvents

    NASA Astrophysics Data System (ADS)

    Santhanam, R.; Noel, M.

    Cyclic voltammetric and scanning electron microscopic investigations on a highly-packed, crystalline, graphite electrode (HPC) and on a polypropylene composite graphite electrode (CPP) containing 20 wt.% polypropylene binder indicate that the latter has higher mechanical stability and higher electrochemical intercalation/de-intercalation activity. This holds for the intercalation of lithium (Li +) and tetrabutyl ammonium (TBA +) cations from dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF), as well as for the intercalation of perchlorate (Cl0 4-) and fluoroborate (Bf 4-) anions from propylene carbonate (PC) and acetonitrile (AN). There is a linear correlation between the threshold potential for the beginning of intercalation ( Eth) and the intercalation/de-intercalation efficiency (IDE) for cationic intercalation. In the case of anionic intercalation, two distinct linear relationships for HPC and CPP electrodes are observed. Competitive oxidation processes reduce the IDE on the HPC electrode.

  9. Synthesis and characterization of Mn intercalated Mg-Al hydrotalcite.

    PubMed

    Yang, Chengxue; Liao, Libing; Lv, Guocheng; Wu, Limei; Mei, Lefu; Li, Zhaohui

    2016-10-01

    Mn intercalated hydrotalcite was prepared using a reconstruction method. And Mn intercalation was confirmed by XRD, FTIR, and thermal analyses. The different valences of Mn were present as determined by XPS. Calcination slightly promoted the isomorphic replacement of Mn(2+) and Mn(3+) for Mg(2+) and Al(3+), especially the replacement of Mn(2+) for Mg(2+) and Al(3+), and to some extent, reduced Mn intercalation. Ultrasonic treatment significantly increased Mn intercalation in permanganate form (Mn(7+)), and promoted the replacement of Mn(2+) for Mg(2+) and Al(3+). XRF analysis showed that ultrasonic treatment decreased the unbalanced layer charge of Mn intercalated hydrotalcite, while prolonged calcination increased it. These results may provide guidance on the preparation and application of Mn intercalated hydrotalcite. Extended calcination time and ultrasonic vibration increased the interlayer spacing of hydrotalcite, as a result of reduction in layer charge. As the layer charge was not completely balanced after Mn intercalation, a certain amount of CO3(2-) was re-adsorbed into the interlayer space. Mn-hydrotalcites with different layer charges, different contents of Mn with varying valences are expected to have different performances in the process of adsorption, degradation, and catalysis. PMID:27380016

  10. Intercalation studies of zinc hydroxide chloride: Ammonia and amino acids

    SciTech Connect

    Arizaga, Gregorio Guadalupe Carbajal

    2012-01-15

    Zinc hydroxide chloride (ZHC) is a layered hydroxide salt with formula Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}2H{sub 2}O. It was tested as intercalation matrix for the first time and results were compared with intercalation products of the well-known zinc hydroxide nitrate and a Zn/Al layered double hydroxide. Ammonia was intercalated into ZHC, while no significant intercalation occurred in ZHN. Aspartic acid intercalation was only achieved by co-precipitation at pH=10 with ZHC and pH=8 with zinc hydroxide nitrate. Higher pH resistance in ZHC favored total deprotonation of both carboxylic groups of the Asp molecule. ZHC conferred more thermal protection against Asp combustion presenting exothermic peaks even at 452 Degree-Sign C while the exothermic event in ZHN was 366 Degree-Sign C and in the LDH at 276 Degree-Sign C. - Graphical abstract: The zinc hydroxide chloride (ZHC) with formula Zn{sub 5}(OH){sub 8}Cl{sub 2}{center_dot}2H{sub 2}O was tested as intercalation matrix. In comparison with the well-known zinc hydroxide nitrate (ZHN) and layered double hydroxides (LDH), ZHC was the best matrix for thermal protection of Asp combustion, presenting exothermic peaks even at 452 Degree-Sign C, while the highest exothermic event in ZHN was at 366 Degree-Sign C, and in the LDH it was at 276 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Zinc hydroxide chloride (ZHC) was tested as intercalation matrix for the first time. Black-Right-Pointing-Pointer ZHC has higher chemical and thermal stability than zinc hydroxide nitrate and LDH. Black-Right-Pointing-Pointer NH{sub 3} molecules can be intercalated into ZHC. Black-Right-Pointing-Pointer The amino group of amino acids limits the intercalation by ion-exchange.

  11. Prediction of superconductivity in Li-intercalated bilayer phosphorene

    SciTech Connect

    Huang, G. Q.; Xing, Z. W.; Xing, D. Y.

    2015-03-16

    It is shown that bilayer phosphorene can be transformed from a direct-gap semiconductor to a BCS superconductor by intercalating Li atoms. For the Li-intercalated bilayer phosphorene, we find that the electron occupation of Li-derived band is small and superconductivity is intrinsic. With increasing the intercalation of Li atoms, both increased metallicity and strong electron-phonon coupling are favorable for the enhancement of superconductivity. The obtained electron-phonon coupling λ can be larger than 1 and the superconducting temperature T{sub c} can be increased up to 16.5 K, suggesting that phosphorene may be a good candidate for a nanoscale superconductor.

  12. Dissecting the Dynamic Pathways of Stereoselective DNA Threading Intercalation.

    PubMed

    Almaqwashi, Ali A; Andersson, Johanna; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C

    2016-03-29

    DNA intercalators that have high affinity and slow kinetics are developed for potential DNA-targeted therapeutics. Although many natural intercalators contain multiple chiral subunits, only intercalators with a single chiral unit have been quantitatively probed. Dumbbell-shaped DNA threading intercalators represent the next order of structural complexity relative to simple intercalators, and can provide significant insights into the stereoselectivity of DNA-ligand intercalation. We investigated DNA threading intercalation by binuclear ruthenium complex [μ-dppzip(phen)4Ru2](4+) (Piz). Four Piz stereoisomers are defined by the chirality of the intercalating subunit (Ru(phen)2dppz) and the distal subunit (Ru(phen)2ip), respectively, each of which can be either right-handed (Δ) or left-handed (Λ). We used optical tweezers to measure single DNA molecule elongation due to threading intercalation, revealing force-dependent DNA intercalation rates and equilibrium dissociation constants. The force spectroscopy analysis provided the zero-force DNA binding affinity, the equilibrium DNA-ligand elongation Δxeq, and the dynamic DNA structural deformations during ligand association xon and dissociation xoff. We found that Piz stereoisomers exhibit over 20-fold differences in DNA binding affinity, from a Kd of 27 ± 3 nM for (Δ,Λ)-Piz to a Kd of 622 ± 55 nM for (Λ,Δ)-Piz. The striking affinity decrease is correlated with increasing Δxeq from 0.30 ± 0.02 to 0.48 ± 0.02 nm and xon from 0.25 ± 0.01 to 0.46 ± 0.02 nm, but limited xoff changes. Notably, the affinity and threading kinetics is 10-fold enhanced for right-handed intercalating subunits, and 2- to 5-fold enhanced for left-handed distal subunits. These findings demonstrate sterically dispersed transition pathways and robust DNA structural recognition of chiral intercalators, which are critical for optimizing DNA binding affinity and kinetics. PMID:27028636

  13. Amine-intercalated α-zirconium phosphates as lubricant additives

    NASA Astrophysics Data System (ADS)

    Xiao, Huaping; Dai, Wei; Kan, Yuwei; Clearfield, Abraham; Liang, Hong

    2015-02-01

    In this study, three types of amines intercalated α-zirconium phosphate nanosheets with different interspaces were synthesized and examined as lubricant additives to a mineral oil. Results from tribological experiments illustrated that these additives improved lubricating performance. Results of rheological experiments showed that the viscosity of the mineral oil was effectively reduced with the addition of α-zirconium phosphate nanosheets. The two-dimensional structure, with larger interspaces, resulting from amine intercalation, exhibited improved effectiveness in reducing viscosity. This study demonstrates that the nanosheet structure of α-zirconium phosphates is effective in friction reduction. The manufacture of lubricants with tailored viscosity is possible by using different intercalators.

  14. The intercalation of DNA double helices with doxorubicin and nogalamycin.

    PubMed

    Box, Vernon G S

    2007-07-01

    A variety of molecules bind to DNA in its major and minor grooves, and some, like the anthraquinoids, are known to form intercalates in which these molecules are inserted directly into the double helix, between the bases. Several researchers have pointed to an electron transfer mechanism (leading to ion pairing) as one of the factors that could hold the intercalated entities like doxorubicin in place, but the bulky anthraquinone nogalamycin did not seem to become engaged in electron transfer. The molecular modeling program STR3DI32 was used to investigate the stabilities of these intercalated anthraquinone before any possible electron transfer has occurred. PMID:17046298

  15. Intercalated samarium as an agent enabling the intercalation of oxygen under a monolayer graphene film on iridium

    NASA Astrophysics Data System (ADS)

    Afanas'eva, E. Yu.; Rut'kov, E. V.; Gall', N. R.

    2016-06-01

    Using thermal desorption time-of-flight mass spectrometry and thermionic methods, it is shown that oxygen does not intercalate under a graphene monolayer grown correctly on iridium, at least at temperatures of T = 300-400 K and exposures below 12000 L. However, if the graphene film on iridium is preliminary intercalated with samarium atoms (up to coverage of θSm = 0.2-0.45), the penetration of oxygen atoms under the graphene film is observed. The oxygen atoms in the intercalated state are chemically bonded to samarium atoms and remain under graphene up to high temperatures (~2150 K).

  16. Kidney α-Intercalated Cells, NGAL and Urinary Tract Infection

    PubMed Central

    Chen, Lihe; Zhang, Wenzheng

    2016-01-01

    It is well known that kidney α-intercalated cells can acidify the urine and acidified urine can inhibit bacterial growth and other urinary organisms. However, regulation of acid-base balance rather than a dedicated function in preventing urinary tract infection has been assigned to α-intercalated cells. A series of studies, culminated by the publication of a paper (J Clin Invest. 2014 Jul 1;124(7):2963–76) from Dr. Barasch’s lab unearthed a novel mechanism by which α-intercalated cells function in the innate immune defense of urinary tract infection. This mechanism involves production and release of neutrophil gelatinase-associated lipocalin by α-intercalated cells to chelate the siderophore containing host iron to achieve bacteriostasis.

  17. Method for intercalating alkali metal ions into carbon electrodes

    DOEpatents

    Doeff, M.M.; Ma, Y.; Visco, S.J.; DeJonghe, L.

    1995-08-22

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

  18. Method for intercalating alkali metal ions into carbon electrodes

    DOEpatents

    Doeff, Marca M.; Ma, Yanping; Visco, Steven J.; DeJonghe, Lutgard

    1995-01-01

    A low cost, relatively flexible, carbon electrode for use in a secondary battery is described. A method is provided for producing same, including intercalating alkali metal salts such as sodium and lithium into carbon.

  19. Intercalation of a block co-polymer in kaolinite.

    PubMed

    Fafard, Jonathan; Detellier, Christian

    2015-07-15

    Intercalates of kaolinite/Polyethylene-block-poly (ethylene glycol) were successfully prepared by melt intercalation of the polymer with a kaolinite: dimethyl sulfoxide pre-intercalate. Powder X-ray diffraction gives an 11.05 Å d-spacing which remains after washing the material with water. Thermal gravimetric analysis and nuclear magnetic resonance confirm the presence of the polymer in the prepared material. Perturbation of the kaolinite hydroxyl stretch and the polymer's CH2 bending modes in the materials' infrared spectrum suggest strong interaction between the aluminol clay sheet and the ethylene glycol units in the polymer. Dipolar dephasing studies show both polymer blocks experience a significant loss in mobility in the prepared material, indicative of intercalation. The presence of highly hydrophobic polyethylene inside kaolinite is expected to drastically modify the nature of the interlayer space, and could be of interest for applications where retention or sequestration of hydrophobic species is required. PMID:25841062

  20. Graphitized needle cokes and natural graphites for lithium intercalation

    SciTech Connect

    Tran, T.D.; Spellman, L.M.; Pekala, R.W.; Goldberger, W.M.; Kinoshita, K.

    1996-05-10

    This paper examined effects of heat treatment and milling (before or after heat treatment) on the (electrochemical) intercalating ability of needle petroleum coke; natural graphite particles are included for comparison. 1 tab, 4 figs, 7 refs.

  1. Effect of Diffusion on Lithium Intercalation in Titanium Dioxide

    NASA Astrophysics Data System (ADS)

    Koudriachova, Marina V.; Harrison, Nicholas M.; de Leeuw, Simon W.

    2001-02-01

    A new model of Li intercalation into rutile and anatase structured titania has been developed from first principles calculations. The model includes both thermodynamic and kinetic effects and explains the observed differences in intercalation behavior and their temperature dependence. The important role of strong local deformations of the lattice and elastic screening of interlithium interactions is demonstrated. In addition, a new phase of LiTiO2 is reported.

  2. Electronic Band Engineering of Epitaxial Graphene by Atomic Intercalation

    NASA Astrophysics Data System (ADS)

    Jayasekera, Thushari; Sandin, Andreas; Xu, Shu; Wheeler, Virginia; Gaskill, D. K.; Rowe, J. E.; Kim, K. W.; Dougherty, Daniel B.; Buongiorno Nardelli, M.

    2012-02-01

    Using calculations from first principles, we have investigated possible ways of engineering the electronic band structure of epitaxial graphene on SiC. In particular, intercalation of different atomic species, such as Hydrogen, Fluorine, Sodium, Germanium, Carbon and Silicon is shown to modify and tune the interface electronic properties and band alignments. Our results suggest that intercalation in graphene is quite different from that in graphite, and could provide a fundamentally new way to achieve electronic control in graphene electronics.

  3. Intercalation-driven reversible control of magnetism in bulk ferromagnets.

    PubMed

    Dasgupta, Subho; Das, Bijoy; Knapp, Michael; Brand, Richard A; Ehrenberg, Helmut; Kruk, Robert; Hahn, Horst

    2014-07-16

    An extension in magnetoelectric effects is proposed to include reversible chemistry-controlled magnetization variations. This ion-intercalation-driven magnetic control can be fully reversible and pertinent to bulk material volumes. The concept is demonstrated for ferromagnetic iron oxide where the intercalated lithium ions cause valence change and partial redistribution of Fe(3+) cations yielding a large and fully reversible change in magnetization at room temperature. PMID:24591165

  4. Electronic properties of carbon fibers intercalated with copper chloride

    NASA Technical Reports Server (NTRS)

    Oshima, H.; Natarajan, V.; Woollam, J. A.; Yavrouian, A.; Haugland, E. J.; Tsuzuku, T.

    1984-01-01

    Copper chloride intercalated pitch-based carbon fibers are found to have electrical resistivities as low as 12.9 micro-ohm-cm, and are air- and thermally-stable at and above room temperature. This is therefore a good candidate system for conductor application. In addition, Shubnikov-deHaas quantum oscillatory effects were found, and electronic properties of the intercalated fiber are studied using magnetic fields to 20 tesla.

  5. Obtaining graphene nanoplatelets from various graphite intercalation compounds

    NASA Astrophysics Data System (ADS)

    Melezhyk, A.; Galunin, E.; Memetov, N.

    2015-11-01

    The work compares the exfoliation ability of different graphite materials (expanded graphite intercalation compound, thermally expanded and oxidatively intercalated graphites) and describes the properties of graphene nanoplatelets (GNPs) obtained dependently on intercalation/deintercalation conditions and reagents. Among the studied materials, the graphite intercalated with ammonium persulfate in sulfuric acid and expanded at 40 °C possesses the maximum ability for ultrasonic exfoliation in the presence of a surfactant. The exfoliation efficiency strongly depends on the content of water in sulfuric acid during the intercalation. The highest efficiency was achieved for the expanded graphite intercalation compound (EGIC) prepared in sulfuric acid containing diluted oleum, which may be explained by increased acidity of the medium and, correspondingly, redox potential of the persulfate compound. This is also related to increased amounts of oxygen groups in the GNPs obtained from the EGIC synthesized in 100% sulfuric acid and diluted oleum. Besides, the nature of surface groups on the GNPs strongly depends on the nature of a deintercalating reagent. Thus, the treatment of the EGIC with different nucleophilic molecules (such as water, ammonia, carbamide, hexamethylenetetramine, organic amines, etc.) can yield GNPs with various surface groups. The interaction between the EGIC and nucleophilic molecules does not only include the substitution of sulfate groups, but also redox reactions with participation of graphene layers. Depending on the nature of the nucleophile, those reactions can lead to the formation of different groups attached to the graphene surface. GNPs with almost pure surface were obtained when using ammonia and carbamide.

  6. Stochastic Terminal Dynamics in Epithelial Cell Intercalation

    NASA Astrophysics Data System (ADS)

    Eule, Stephan; Metzger, Jakob; Reichl, Lars; Kong, Deqing; Zhang, Yujun; Grosshans, Joerg; Wolf, Fred

    2015-03-01

    We found that the constriction of epithelial cell contacts during intercalation in germ band extension in Drosophila embryos follows intriguingly simple quantitative laws. The mean contact length < L > follows < L > (t) ~(T - t) α , where T is the finite collapse time; the time dependent variance of contact length is proportional to the square of the mean; finally the time dependent probability density of the contact lengths remains close to Gaussian during the entire process. These observations suggest that the dynamics of contact collapse can be captured by a stochastic differential equation analytically tractable in small noise approximation. Here, we present such a model, providing an effective description of the non-equilibrium statistical mechanics of contact collapse. All model parameters are fixed by measurements of time dependent mean and variance of contact lengths. The model predicts the contact length covariance function that we obtain in closed form. The contact length covariance function closely matches experimental observations suggesting that the model well captures the dynamics of contact collapse.

  7. Space Discovery.

    ERIC Educational Resources Information Center

    Blackman, Joan

    1998-01-01

    Describes one teacher's experience taking Space Discovery courses that were sponsored by the United States Space Foundation (USSF). These courses examine the history of space science, theory of orbits and rocketry, the effects of living in outer space on humans, and space weather. (DDR)

  8. Discriminating Intercalative Effects of Threading Intercalator Nogalamycin, from Classical Intercalator Daunomycin, Using Single Molecule Atomic Force Spectroscopy.

    PubMed

    Banerjee, T; Banerjee, S; Sett, S; Ghosh, S; Rakshit, T; Mukhopadhyay, R

    2016-01-01

    DNA threading intercalators are a unique class of intercalating agents, albeit little biophysical information is available on their intercalative actions. Herein, the intercalative effects of nogalamycin, which is a naturally-occurring DNA threading intercalator, have been investigated by high-resolution atomic force microscopy (AFM) and spectroscopy (AFS). The results have been compared with those of the well-known chemotherapeutic drug daunomycin, which is a non-threading classical intercalator bearing structural similarity to nogalamycin. A comparative AFM assessment revealed a greater increase in DNA contour length over the entire incubation period of 48 h for nogalamycin treatment, whereas the contour length increase manifested faster in case of daunomycin. The elastic response of single DNA molecules to an externally applied force was investigated by the single molecule AFS approach. Characteristic mechanical fingerprints in the overstretching behaviour clearly distinguished the nogalamycin/daunomycin-treated dsDNA from untreated dsDNA-the former appearing less elastic than the latter, and the nogalamycin-treated DNA distinguished from the daunomycin-treated DNA-the classically intercalated dsDNA appearing the least elastic. A single molecule AFS-based discrimination of threading intercalation from the classical type is being reported for the first time. PMID:27183010

  9. Discriminating Intercalative Effects of Threading Intercalator Nogalamycin, from Classical Intercalator Daunomycin, Using Single Molecule Atomic Force Spectroscopy

    PubMed Central

    Sett, S.; Ghosh, S.; Rakshit, T.; Mukhopadhyay, R.

    2016-01-01

    DNA threading intercalators are a unique class of intercalating agents, albeit little biophysical information is available on their intercalative actions. Herein, the intercalative effects of nogalamycin, which is a naturally-occurring DNA threading intercalator, have been investigated by high-resolution atomic force microscopy (AFM) and spectroscopy (AFS). The results have been compared with those of the well-known chemotherapeutic drug daunomycin, which is a non-threading classical intercalator bearing structural similarity to nogalamycin. A comparative AFM assessment revealed a greater increase in DNA contour length over the entire incubation period of 48 h for nogalamycin treatment, whereas the contour length increase manifested faster in case of daunomycin. The elastic response of single DNA molecules to an externally applied force was investigated by the single molecule AFS approach. Characteristic mechanical fingerprints in the overstretching behaviour clearly distinguished the nogalamycin/daunomycin-treated dsDNA from untreated dsDNA—the former appearing less elastic than the latter, and the nogalamycin-treated DNA distinguished from the daunomycin-treated DNA—the classically intercalated dsDNA appearing the least elastic. A single molecule AFS-based discrimination of threading intercalation from the classical type is being reported for the first time. PMID:27183010

  10. Application of photochemical reaction in electrochemical detection of DNA intercalation.

    PubMed

    Pandey, P C; Weetall, H H

    1994-04-15

    A flow injection analysis (FIA) system for the detection of the compounds that intercalate within DNA is reported. A derivative of 9,10-anthraquinone has been used as the reference compound for photoelectrochemical detection. The sodium salts of 9,10-anthraquinone-2,6-disulfonic acid and 9,10-anthraquinone-2-sulfonic acid are photochemically activated and then reduced in the presence of an electron donor (glucose). The electrochemical signal is based on the measurement of the anodic current resulting from the oxidation of the reduced form of 9,10-anthraquinone. The reduced form of the 9,10-anthraquinone is oxidized through a mediated mechanism at the surface of a tetracyanoquinodimethane-(TCNQ)-modified graphite paste electrode covered by a Nucleopore membrane. TCNQ acts as an efficient mediator for the oxidation of reduced 9,10-anthraquinone. Cyclic voltammetry, photocyclic voltammetry, and the photoelectrochemical FIA response of 9,10-anthraquinone are reported. Experimental results show that these anthraquinones can be intercalated within the helix of double-stranded calf thymus DNA. The anthraquinone molecules that are intercalated within DNA cannot be oxidized due to their limited transport to the modified electrode surface. This results in a decrease in the anodic current at a constant concentration of anthraquinone after intercalation. There is a linear relation between the decrease in electrochemical response and the DNA concentration at a constant concentration of anthraquinone. The intercalated anthraquinone molecules can be completely replaced by another intercalating agent (i.e., ethidium bromide) that is more strongly intercalated within DNA, thereby regenerating the electrochemical response.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8210041

  11. Intercalation of ethylene glycol into yttrium hydroxide layered materials.

    PubMed

    Xi, Yuanzhou; Davis, Robert J

    2010-04-19

    Intercalation of ethylene glycol into layered yttrium hydroxide containing nitrate counterions was accomplished by heating the reagents in a methanol solution of sodium methoxide under autogenous pressure at 413 K for 20 h. The resulting crystalline material had an expanded interlayer distance of 10.96 A, confirming the intercalation of an ethylene glycol derived species. Characterization of the material by FT-IR spectroscopy, thermogravimetric analysis, and the catalytic transesterification of tributyrin with methanol was consistent with direct bonding of ethylene glycolate anions (O(2)C(2)H(5)(-)) to the yttrium hydroxide layers, forming Y-O-C bonds. The layers of the material are proposed to be held together by H-bonding between the hydroxyls of grafted ethylene glycol molecules attached to adjacent layers. Glycerol can also be intercalated into yttrium hydroxide layered materials by a similar method. PMID:20302308

  12. The preliminary feasibility of intercalated graphite railgun armatures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Gooden, Clarence E.; Yashan, Doreen; Naud, Steve

    1991-01-01

    Graphite intercalation compounds may provide an excellent material for the fabrication of electromagnetic railgun armatures. As a pulse of power is fed into the armature the intercalate could be excited into the plasma state around the edges of the armature, while the bulk of the current would be carried through the graphite block. Such an armature would have both diffuse plasma armatures and bulk conduction armatures. In addition, the highly anisotropic nature of these materials could enable the electrical and thermal conductivity to be tailored to meet the specific requirements of electromagnetic railgun armatures. Preliminary investigations have been performed in an attempt to determine the feasibility of using graphite intercalation compounds as railgun armatures. Issues of fabrication, resistivity, stability, and electrical current spreading have been addressed for the case of highly oriented pyrolytic graphite.

  13. The preliminary feasibility of intercalated graphite railgun armatures

    SciTech Connect

    Gaier, J.R. . Lewis Research Center); Gooden, C.E. ); Yashan, D. ); Naud, S. )

    1991-01-01

    This paper reports on graphite intercalation compounds which may provide an excellent material for the fabrication of electro-magnetic railgun armatures. As a pulse of power is fed into the armature the intercalate could be excited into the plasma state around the edges of the armature, while the bulk of the current would be carried through the graphite block. Such an armature would have desirable characteristics of both diffuse plasma armatures and bulk conduction armatures. In addition, the highly anisotropic nature of these materials could enable the electrical and thermal conductivity to be tailored to meet the specific requirements of electromagnetic railgun armatures. Preliminary investigations have been performed in an attempt to determine the feasibility of using graphite intercalation compounds as railgun armatures. Issues of fabrication, resistivity, stability, and electrical current spreading have been addressed for the case of highly oriented pyrolytic graphite.

  14. The backside of graphene: manipulating adsorption by intercalation.

    PubMed

    Schumacher, Stefan; Wehling, Tim O; Lazić, Predrag; Runte, Sven; Förster, Daniel F; Busse, Carsten; Petrović, Marin; Kralj, Marko; Blügel, Stefan; Atodiresei, Nicolae; Caciuc, Vasile; Michely, Thomas

    2013-11-13

    The ease by which graphene is affected through contact with other materials is one of its unique features and defines an integral part of its potential for applications. Here, it will be demonstrated that intercalation, the insertion of atomic layers in between the backside of graphene and the supporting substrate, is an efficient tool to change its interaction with the environment on the frontside. By partial intercalation of graphene on Ir(111) with Eu or Cs we induce strongly n-doped graphene patches through the contact with these intercalants. They coexist with nonintercalated, slightly p-doped graphene patches. We employ these backside doping patterns to directly visualize doping induced binding energy differences of ionic adsorbates to graphene through low-temperature scanning tunneling microscopy. Density functional theory confirms these binding energy differences and shows that they are related to the graphene doping level. PMID:24131290

  15. Preparation of graphite intercalation compounds containing oligo and polyethers

    NASA Astrophysics Data System (ADS)

    Zhang, Hanyang; Lerner, Michael M.

    2016-02-01

    Layered host-polymer nanocomposites comprising polymeric guests between inorganic sheets have been prepared with many inorganic hosts, but there is limited evidence for the incorporation of polymeric guests into graphite. Here we report for the first time the preparation, and structural and compositional characterization of graphite intercalation compounds (GICs) containing polyether bilayers. The new GICs are obtained by either (1) reductive intercalation of graphite with an alkali metal in the presence of an oligo or polyether and an electrocatalyst, or (2) co-intercalate exchange of an amine for an oligo or polyether in a donor-type GIC. Structural characterization of products using powder X-ray diffraction, Raman spectroscopy, and thermal analyses supports the formation of well-ordered, first-stage GICs containing alkali metal cations and oligo or polyether bilayers between reduced graphene sheets.Layered host-polymer nanocomposites comprising polymeric guests between inorganic sheets have been prepared with many inorganic hosts, but there is limited evidence for the incorporation of polymeric guests into graphite. Here we report for the first time the preparation, and structural and compositional characterization of graphite intercalation compounds (GICs) containing polyether bilayers. The new GICs are obtained by either (1) reductive intercalation of graphite with an alkali metal in the presence of an oligo or polyether and an electrocatalyst, or (2) co-intercalate exchange of an amine for an oligo or polyether in a donor-type GIC. Structural characterization of products using powder X-ray diffraction, Raman spectroscopy, and thermal analyses supports the formation of well-ordered, first-stage GICs containing alkali metal cations and oligo or polyether bilayers between reduced graphene sheets. Electronic supplementary information (ESI) available: Domain size, additional Raman spectra info, compositional calculation, and packing fractions. See DOI: 10.1039/c5

  16. Intercalation of paracetamol into the hydrotalcite-like host

    SciTech Connect

    Kovanda, Frantisek; Maryskova, Zuzana; Kovar, Petr

    2011-12-15

    Hydrotalcite-like compounds are often used as host structures for intercalation of various anionic species. The product intercalated with the nonionic, water-soluble pharmaceuticals paracetamol, N-(4-hydroxyphenyl)acetamide, was prepared by rehydration of the Mg-Al mixed oxide obtained by calcination of hydrotalcite-like precursor at 500 Degree-Sign C. The successful intercalation of paracetamol molecules into the interlayer space was confirmed by powder X-ray diffraction and infrared spectroscopy measurements. Molecular simulations showed that the phenolic hydroxyl groups of paracetamol interact with hydroxide sheets of the host via the hydroxyl groups of the positively charged sites of Al-containing octahedra; the interlayer water molecules are located mostly near the hydroxide sheets. The arrangement of paracetamol molecules in the interlayer is rather disordered and interactions between neighboring molecules cause their tilting towards the hydroxide sheets. Dissolution tests in various media showed slower release of paracetamol intercalated in the hydrotalcite-like host in comparison with tablets containing the powdered pharmaceuticals. - Graphical abstract: Molecular simulations showed disordered arrangement of paracetamol molecules in the interlayer; most of the interlayer water molecules are located near the hydroxide sheets. Black-Small-Square Highlights: Black-Right-Pointing-Pointer Paracetamol was intercalated in Mg-Al hydrotalcite-like host by rehydration/reconstruction procedure. Black-Right-Pointing-Pointer Paracetamol phenolic groups interact with positively charged sites in hydroxide sheets. Black-Right-Pointing-Pointer Molecular simulations showed disordered arrangement of guest molecules in the interlayer. Black-Right-Pointing-Pointer Slower release of paracetamol intercalated in the hydrotalcite-like host was observed.

  17. Revisiting the domain model for lithium intercalated graphite

    SciTech Connect

    Krishnan, Sridevi; Brenet, Gilles; Caliste, Damien; Genovese, Luigi; Deutsch, Thierry; Pochet, Pascal

    2013-12-16

    In this Letter, we study the stability of the domain model for lithium intercalated graphite in stages III and II by means of Density Functional Theory and Kinetic Lattice Monte Carlo simulations. We find that the domain model is either thermodynamically or kinetically stable when compared to the standard model in stages III and II. The existence of domains in the intercalation sequence is well supported by recent high resolution transmission electron microscope observations in lithiated graphite. Moreover, we predict that such domain staging sequences leads to a wide range of diffusivity as reported in experiments.

  18. Layered Compounds and Intercalation Chemistry: An Example of Chemistry and Diffusion in Solids.

    ERIC Educational Resources Information Center

    Whittingham, M. Stanley; Chianelli, Russell R.

    1980-01-01

    Considers a few areas of oxide/sulfide and intercalation-type chemistry. Discusses synthesis of the disulfides of the metals of group IVB, VB, and VIB; the intercalation reaction between lithium and titanium disulfide; other intercalates; and sulfide catalysts. (CS)

  19. Discovery Scarp

    NASA Technical Reports Server (NTRS)

    1974-01-01

    One of the most prominent lobate scarps (Discovery Scarp), photographed by Mariner 10 during it's first encounter with Mercury, is located at the center of this image (extending from the top to near bottom). This scarp is about 350 kilometers long and transects two craters 35 and 55 kilometers in diameter. The maximum height of the scarp south of the 55-kilometer crater is about 3 kilometers. Notice the shallow older crater (near the center of the image) perched on the crest of the scarp. (FDS 17389 and 27399)

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  20. Exfoliation of Hexagonal Boron Nitride via Ferric Chloride Intercalation

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh; Hurst, Janet; Santiago, Diana; Rogers, Richard B.

    2014-01-01

    Sodium fluoride (NaF) was used as an activation agent to successfully intercalate ferric chloride (FeCl3) into hexagonal boron nitride (hBN). This reaction caused the hBN mass to increase by approx.100 percent, the lattice parameter c to decrease from 6.6585 to between 6.6565 and 6.6569 ?, the x-ray diffraction (XRD) (002) peak to widen from 0.01deg to 0.05deg of the full width half maximum value, the Fourier transform infrared (FTIR) spectrum's broad band (1277/cm peak) to change shape, and new FTIR bands to emerge at 3700 to 2700 and 1600/cm. This indicates hBN's structural and chemical properties are significantly changed. The intercalated product was hygroscopic and interacted with moisture in the air to cause further structural and chemical changes (from XRD and FTIR). During a 24-h hold at room temperature in air with 100 percent relative humidity, the mass increased another 141 percent. The intercalated product, hydrated or not, can be heated to 750 C in air to cause exfoliation. Exfoliation becomes significant after two intercalation-air heating cycles, when 20-nm nanosheets are commonly found. Structural and chemical changes indicated by XRD and FTIR data were nearly reversed after the product was placed in hydrochloric acid (HCl), resulting in purified, exfoliated, thin hBN products.

  1. Kinetics of the Formation of Intercalation Compounds in Crystalline Graphite

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Hickey, G. S.

    1995-01-01

    Crystalline graphite has a structure that can be best described as an ordered stack of flat aromatic layers. It is known to form intercalation compounds with bromine and nitric acid. Their formation was studied using thermal measurements and analytical techniques. Samples of graphite treated with either bromine or nitric acid were prepared by contacting these reagents with powdered graphite.

  2. Intercalation of papain enzyme into hydrotalcite type layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Zou, N.; Plank, J.

    2012-09-01

    Intercalation of proteolytic enzyme papain into hydrotalcite type LDH structure was achieved by controlled co-precipitation at pH=9.0 in the presence of papain. Characterization of the MgAl-papain-LDH phase was carried out using X-ray powder diffraction (XRD), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). According to XRD, papain was successfully intercalated. The d-value for the basal spacing of MgAl-papain-LDH was found at ˜5.3 nm. Consequently, original papain (hydrodynamic diameter ˜7.2 nm) attains a compressed conformation during intercalation.Formation of MgAl-papain-LDH was confirmed by elemental analysis and transmission electron microscopy (TEM). Under SEM, MgAl-papain-LDH phases appear as nanothin platelets which are intergrown to flower-like aggregates. Steric size and activity of the enzyme was retained after deintercalation from MgAl-LDH framework, as was evidenced by light scattering and UV/vis measurements. Thus, papain is not denatured during intercalation, and LDH is a suitable host structure which can provide a time-controlled release of the biomolecule.

  3. Methotrexate intercalated ZnAl-layered double hydroxide

    SciTech Connect

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-15

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate ({approx}34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: > ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. > XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. > TG and CHN analyses showed {approx}34 wt% of methotrexate loading into the nanohybrid. > Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

  4. Tethered naphthalene diimide-based intercalators for DNA triplex stabilization

    PubMed Central

    Gianolio, Diego A.; Segismundo, Joanna M.; McLaughlin, Larry W.

    2000-01-01

    The synthesis and triplex stabilizing properties of oligodeoxyribonucleotides functionalized at the 5′- and/or 3′-termini with a naphthalene diimide-based (NDI) intercalator is described. The NDI intercalator was prepared in a single step from the corresponding dianhydride and was attached to the 5′-terminus of an oligodeoxyribonucleotide following a reverse coupling procedure. The DMT protecting group was removed and the sequence phosphitylated to generate the phosphoramidite derivative on the 5′-terminus of the support-bound oligodeoxyribonucleotide. The NDI intercalator with a free hydroxyl was then added in the presence of tetrazole. Attachment of the NDI to the 3′-terminus relied upon a tethered amino group that could be functionalized first with the naphthalene dianhydride, which was subsequently converted to the diimide. Using both procedures, an oligonucleotide conjugate was prepared having the NDI intercalator at both the 5′- and 3′-termini. Thermal denaturation studies were used to determine the remarkable gain in stability for triplexes formed when the NDI-conjugated oligonucleotide was present as the third strand in the complex. PMID:10773082

  5. Capacitive Sensing of Intercalated H2O Molecules Using Graphene.

    PubMed

    Olson, Eric J; Ma, Rui; Sun, Tao; Ebrish, Mona A; Haratipour, Nazila; Min, Kyoungmin; Aluru, Narayana R; Koester, Steven J

    2015-11-25

    Understanding the interactions of ambient molecules with graphene and adjacent dielectrics is of fundamental importance for a range of graphene-based devices, particularly sensors, where such interactions could influence the operation of the device. It is well-known that water can be trapped underneath graphene and its host substrate; however, the electrical effect of water beneath graphene and the dynamics of how the interfacial water changes with different ambient conditions has not been quantified. Here, using a metal-oxide-graphene variable-capacitor (varactor) structure, we show that graphene can be used to capacitively sense the intercalation of water between graphene and HfO2 and that this process is reversible on a fast time scale. Atomic force microscopy is used to confirm the intercalation and quantify the displacement of graphene as a function of humidity. Density functional theory simulations are used to quantify the displacement of graphene induced by intercalated water and also explain the observed Dirac point shifts as being due to the combined effect of water and oxygen on the carrier concentration in the graphene. Finally, molecular dynamics simulations indicate that a likely mechanism for the intercalation involves adsorption and lateral diffusion of water molecules beneath the graphene. PMID:26502269

  6. Intercalation of paracetamol into the hydrotalcite-like host

    NASA Astrophysics Data System (ADS)

    Kovanda, František; Maryšková, Zuzana; Kovář, Petr

    2011-12-01

    Hydrotalcite-like compounds are often used as host structures for intercalation of various anionic species. The product intercalated with the nonionic, water-soluble pharmaceuticals paracetamol, N-(4-hydroxyphenyl)acetamide, was prepared by rehydration of the Mg-Al mixed oxide obtained by calcination of hydrotalcite-like precursor at 500 °C. The successful intercalation of paracetamol molecules into the interlayer space was confirmed by powder X-ray diffraction and infrared spectroscopy measurements. Molecular simulations showed that the phenolic hydroxyl groups of paracetamol interact with hydroxide sheets of the host via the hydroxyl groups of the positively charged sites of Al-containing octahedra; the interlayer water molecules are located mostly near the hydroxide sheets. The arrangement of paracetamol molecules in the interlayer is rather disordered and interactions between neighboring molecules cause their tilting towards the hydroxide sheets. Dissolution tests in various media showed slower release of paracetamol intercalated in the hydrotalcite-like host in comparison with tablets containing the powdered pharmaceuticals.

  7. [Raman and infrared spectrograms of organic borate intercalated hydrotalcite].

    PubMed

    Zhang, Jing-Yu; Bai, Zhi-Min; Zhao, Dong

    2013-03-01

    The pattern of X-ray diffraction, the Raman and infrared spectra of organic borate intercalated hydrotalcite were discussed. The well crystallized zinc-aluminum layered double hydroxides (Zn-Al LDHs) intercalated by carbonate ions and borate ions were respectively prepared by co-precipitation method. Patterns of X-ray diffraction showed that the (003) reflection of borate-LDHs was sharp and symmetric and shifted to lower angle than that of carbonate-LDHs. The gallery height of borate-LDHs increased from 0. 28 nm to 0.42 nm after intercalation, indicating that interlayered carbonate ions were substituted by borate anions. The Raman and IR spectra showed that specific bands of carbonate ions in the borate-LDHs disappeared, but with the presence of B3O3(OH)4- X B4O5(OH)4(2-) and B(OH)4- in the interlayer galleries. The hydroxide interlayer anions had a significant influence on the band positions in Raman and infrared spectra of modes related to the hydroxyl group. Our results indicate that single phase and pure borate-pillared LDHs can be obtained using tributyl orthoborate as intercalating agents, and the change in the structure and nature of hydrotalcite can be detected precisely by Raman spectroscopy. PMID:23705437

  8. Technical Report-Final-Electrochemistry of Nanostructured Intercalation Hosts

    SciTech Connect

    Professor William H. Smyrl, Principal Investigator

    2009-03-09

    We have shown that: (1) Li+ ions are inserted reversibly, without diffusion control, up to the level of at least 4 moles Li+ ions per mole for V2O5, in the aerogel (ARG) form (500 m2/g specific surface area) and aerogel-like (ARG-L) form (200 m2/g specific surface area)(6,7,1,2); (2) polyvalent cations (Al+3, Mg+2, Zn+2) may be intercalated reversibly into V2O5 (ARG) with high capacity (approaching 4 equivalents/mole V2O5 (ARG)) for each (5); (3) dopant cations such as Ag+ and Cu+2 increase the conductivity of V2O5 (XRG) up to three orders of magnitude(3), they are electrochemically active – showing reduction to the metallic-state in parallel to intercalation of Li+ ions – but are not released to the electrolyte upon oxidation and Li+ ion release (Cu+2 ions are reduced to Cu metal and reoxidized to Cu+2 in Li+ ion insertion/release cycles, but the copper ions are not released to the electrolyte over more than 400 cycles of the XRG form); (4) we have shown that Cu+2 ion (dopant) and Zn+2 ions (chemical insertion and dopant) occupy the same intercalation site inV2O5 xerogel and aerogel(4); (5) the reversible intercalation of Zn+2, Mg+2, and Al+3 in the ARG(11) indicates that these cations are “mobile”, but that Cu+2 ions and Ag+ ions are “immobile” in the xerogel, i.e., the latter ions are not exchanged with the electrolyte in Li+ ion intercalation cycling(3).

  9. Formation of intercalated illite and kaolinite in the meteoric environment

    SciTech Connect

    Stonecipher, S.A. )

    1990-05-01

    Intercalations of illite and kaolinite are common diagenetic products in many sandstones. Most literature references suggest that these intercalations formed by the progressive growth of illite within preexisting vermiform kaolinite. This process of illitization has been related to the progressive release of potassium from feldspars and micas during middle- to late-stage burial diagenesis. The application of similar time and process connotations to all intercalations of illite and kaolinite is not justified, however. Petrographic studies of sands of different origins have revealed intercalations of kaolinite and illite which appear to have resulted from the progressive growth of kaolinite on or in between the layers of preexisting clay or mica sheets. Expansion of degraded micas in confining pore spaces produced accordion-like structures. Similarly oriented layers in the accordion were infilled with kaolinite producing pseudovermiform booklets. In each case, the kaolinite appears to have formed early in the sand's diagenetic history before much compaction took place. Examples of this fabric will be shown from diverse settings. Provenance, age, and geographic location vary widely; however, in all cases, the sands were deposited in deltaic to shoreline environments which were subjected to extensive meteoric flushing during deposition and early burial. The kaolinite appears to have formed in response to leaching and dissolution of micas and clays in the meteoric environment. This interpretation raises a caveat for petrologists; the determination of which came first, the kaolinite or the intercalated clay, has serious implications not only for the timing and origin of the kaolinite, but also for the depositional setting of the enclosing sand.

  10. Multi-layer and multi-component intercalation at the graphene/Ir(111) interface

    NASA Astrophysics Data System (ADS)

    Bazarnik, Maciej; Decker, Régis; Brede, Jens; Wiesendanger, Roland

    2015-09-01

    We present a scanning tunneling microscopy study of Fe and Co intercalated at the graphene-Ir(111) interface. In the case of Fe, we investigate the morphology of the surface with respect to the annealing temperature, which activates the intercalation, and as a function of coverage. By increasing the coverage we show that it is possible to intercalate multilayers at the interface. Finally, we demonstrate that the successive intercalation of Co and Fe for the same sample leads to distinct adjacent intercalation areas.

  11. Dynamics of graphite fiber intercalation: In situ resistivity measurements with a four point probe

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.

    1984-01-01

    The dynamics of ferric chloride intercalation of single graphite fibers were studied, in situ, using a four point dc bridge. Measurements before, during and after the intercalation showed that the intercalation occurred within minutes at 200 C. Changes in fiber resistivity after exposure to air suggested hydration of the graphite intercalation compound. Deintercalation of the ferric chloride was initiated at temperatures in excess of 400 C. cycling the intercalant into and out of the graphite fiber gave no improvements in fiber resistivity. The activation energy of the ferric chloride intercalation reaction was found to be 17 + or - 4 kcal/mol 1 consistent with the concept of a preliminary nucleation step in the intercalation reaction.

  12. Materials discovery through crystal growth

    NASA Astrophysics Data System (ADS)

    zur Loye, Hans-Conrad

    2016-04-01

    The discovery of new materials and associated desirable properties has been a driving force behind chemical innovation for centuries. When we look at some of the many recent technological advances, and how widespread and significant their impact has been, we appreciate how much they have relied on new materials. The increase in hard drive storage capacity due to new giant magneto-resistive materials, the ever-shrinking cell phone due to improved microwave dielectric materials, the enhancement in lithium battery storage capacity due to new intercalation materials, or the improved capacitor due to new ferroelectric materials are all excellent examples. How were these materials discovered? While there is no single answer, in all cases there was a First-Material, the archetype in which the phenomenon was first observed, the one that led to further investigations and the subsequent preparation of improved 2nd or 3rd generation materials. It is this First-Material, the archetype, that was discovered - often via crystal growth.

  13. DNA Intercalated Psoralen Undergoes Efficient Photoinduced Electron Transfer.

    PubMed

    Fröbel, Sascha; Reiffers, Anna; Torres Ziegenbein, Christian; Gilch, Peter

    2015-04-01

    The interaction of psoralens with DNA has been used for therapeutic and research purposes for decades. Still the photoinduced behavior of psoralens in DNA has never been observed directly. Femtosecond transient absorption spectroscopy is used here to gain direct insight into the photophysics of a DNA-intercalated psoralen (4'-aminomethyl-4,5',8-trimethyl-psoralen (AMT)). Intercalation reduces the excited singlet lifetime of AMT to 4 ps compared with 1400 ps for AMT in water. This singlet quenching prohibits the population of the triplet state that is accessed in free AMT. Instead, a DNA to AMT electron transfer takes place. The resulting radical pair decays primarily via charge recombination with a time constant of 30 ps. The efficient electron transfer observed here reveals a completely new aspect of the psoralen-DNA interaction. PMID:26262984

  14. Graphene on Mica - Intercalated Water Trapped for Life

    PubMed Central

    Ochedowski, O.; Bussmann, B. Kleine; Schleberger, M.

    2014-01-01

    In this work we study the effect of thermal processing of exfoliated graphene on mica with respect to changes in graphene morphology and surface potential. Mild annealing to temperatures of about 200°C leads to the removal of small amounts of intercalated water at graphene edges. By heating to 600°C the areas without intercalated water are substantially increased enabling a quantification of the charge transfer properties of the water layer by locally resolved Kelvin probe force microscopy data. A complete removal on a global scale cannot be achieved because mica begins to decompose at temperatures above 600°C. By correlating Kelvin probe force microscopy and Raman spectroscopy maps we find a transition from p-type to n-type doping of graphene during thermal processing which is driven by the dehydration of the mica substrate and an accumulation of defects in the graphene sheet. PMID:25132493

  15. Tissue tectonics: morphogenetic strain rates, cell shape change and intercalation

    PubMed Central

    Blanchard, Guy B.; Kabla, Alexandre J.; Schultz, Nora L.; Butler, Lucy C.; Sanson, Benedicte; Gorfinkiel, Nicole; Mahadevan, L.; Adams, Richard J.

    2016-01-01

    The dynamic reshaping of tissues during morphogenesis results from a combination of individual cell behaviours and collective cell rearrangements. However, a comprehensive framework to unambiguously measure and link cell behaviour to tissue morphogenesis is lacking. Here we introduce such a kinematic framework, bridging cell and tissue behaviours at an intermediate, mesoscopic, level of cell clusters or domains. By measuring domain deformation in terms of the relative motion of cell positions and the evolution of their shapes, we characterize the basic invariant quantities that measure fundamental classes of cell behaviour, namely tensorial rates of cell shape change and cell intercalation. In doing so we introduce an explicit definition of cell intercalation as a continuous process. We demonstrate how spatiotemporal mapping of strain rates in three models of tissue morphogenesis leads to new insight into morphogenetic mechanisms. Our quantitative approach has broad relevance for the precise characterisation and comparison of morphogenetic phenotypes. PMID:19412170

  16. Sonochemical intercalation of preformed gold nanoparticles into multilayered clays.

    PubMed

    Belova, Valentina; Möhwald, Helmuth; Shchukin, Dmitry G

    2008-09-01

    Multilayered Na (+)-montmorillonite clays intercalated with Au nanoparticles were synthesized by direct ultrasonic impregnation of preformed gold colloid into the clay matrix. The sonicated composite product then consists of Au nanoparticles homogeneously dispersed in the clay. The resulting clay/nano-Au composite was calcined at 800 degrees C and characterized by BET surface area analysis, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared measurements. Nearly spherical-shaped gold nanoparticles, with a size of 6 +/- 0.5 nm, are located in the pores of clay calcined at 800 degrees C. Their nanocomposites are thermally stable as was shown by thermogravimetric analysis. No aggregation of the gold nanoparticles was observed during calcination. The proposed ultrasonic intercalation approach is an universal one and can be employed for synthesis of catalytically active metal-clay nanocomposites stable at high temperatures with high dispersability of the metal nanoparticles in the clay matrix. PMID:18652497

  17. Intercalation of Trichloroethene by Sediment-Associated Clay Minerals

    SciTech Connect

    Matthieu, Donald E.; Brusseau, Mark; Johnson, G. R.; Artiola, J. L.; Bowden, Mark E.; Curry, J. E.

    2013-01-01

    The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site inTucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer dspacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (*26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment.

  18. An advanced model framework for solid electrolyte intercalation batteries.

    PubMed

    Landstorfer, Manuel; Funken, Stefan; Jacob, Timo

    2011-07-28

    Recent developments of solid electrolytes, especially lithium ion conductors, led to all solid state batteries for various applications. In addition, mathematical models sprout for different electrode materials and battery types, but are missing for solid electrolyte cells. We present a mathematical model for ion flux in solid electrolytes, based on non-equilibrium thermodynamics and functional derivatives. Intercalated ion diffusion within the electrodes is further considered, allowing the computation of the ion concentration at the electrode/electrolyte interface. A generalized Frumkin-Butler-Volmer equation describes the kinetics of (de-)intercalation reactions and is here extended to non-blocking electrodes. Using this approach, numerical simulations were carried out to investigate the space charge region at the interface. Finally, discharge simulations were performed to study different limitations of an all solid state battery cell. PMID:21681301

  19. Lithium intercalation behavior of surface modified carbonaceous materials

    SciTech Connect

    Tran, T.D.; Murguia, L.X.; Song, X.; Kinoshita, K.

    1997-07-17

    The surface properties of several well-characterized commercial carbon materials were modified by thermal and chemical treatments. The reversible capacities for lithium intercalation of a sponge green coke and a fuel green coke for lithium intercalation increased by as much as 25% after heat treatment in both reducing (5% H{sub 2}/Ar) and oxidizing (CO{sub 2}) environments. The irreversible capacity loss increased significantly with CO{sub 2} treatment at 800{degrees}C. The trend of larger capacity losses with CO{sub 2} treatment is also observed with a synthetic graphite (SFG6) which was produced by heat treatment at about 3000{degrees}C. Carbon fibers that were first impregnated with LiOH solution followed by reaction with CO{sub 2} to form Li{sub 2}CO{sub 3} tended to show lower irreversible capacity losses.

  20. Multiparameter single-molecule fluorescence measurements of DNA intercalating fluorophores

    NASA Astrophysics Data System (ADS)

    Bowen, Benjamin P.; Enderlein, Jorg; Woodbury, Neal W. T.

    2003-06-01

    Experiments using single-molecules of TOTO-1 intercalated into dsDNA were performed to investigate the DNA sequence dependence on the fluorescence detectable with single-molecule fluorescence spectroscopy. Previous work has shown that there is a difference in the fluorescence lifetime when TOTO-1 is intercalated in poly-AT DNA or in poly-GC DNA. The fluorescence detected from single-molecules in this work for poly-GC and poly-AT DNA showed fluorescence lifetimes of 2.1 and 1.8 nsec, respectively. Analysis of the fluorescence intensity detected from single-molecules of TOTO-1 was performed by fluorescence cross-correlation spectroscopy. TOTO-1 is shown to spend large amounts of time in dark states. These dark states reduce the detectable fluorescence intensity to approximately 10 photons per millisecond on average.

  1. Controlling the photoconductivity: Graphene oxide and polyaniline self assembled intercalation

    SciTech Connect

    Vempati, Sesha; Ozcan, Sefika; Uyar, Tamer

    2015-02-02

    We report on controlling the optoelectronic properties of self-assembled intercalating compound of graphene oxide (GO) and HCl doped polyaniline (PANI). Optical emission and X-ray diffraction studies revealed a secondary doping phenomenon of PANI with –OH and –COOH groups of GO, which essentially arbitrate the intercalation. A control on the polarity and the magnitude of the photoresponse (PR) is harnessed by manipulating the weight ratios of PANI to GO (viz., 1:1.5 and 1:2.2 are abbreviated as PG1.5 and PG2.2, respectively), where ±PR = 100(R{sub Dark} – R{sub UV-Vis})/R{sub Dark} and R corresponds to the resistance of the device in dark or UV-Vis illumination. To be precise, the PR from GO, PANI, PG1.5, and PG2.2 are +34%, −111%, −51%, and +58%, respectively.

  2. Superconductivity in the Graphite Intercalation Compound BaC 6

    NASA Astrophysics Data System (ADS)

    Heguri, Satoshi; Kawade, Naoya; Fujisawa, Takumi; Yamaguchi, Akira; Sumiyama, Akihiko; Tanigaki, Katsumi; Kobayashi, Mototada

    2015-06-01

    Among many two-dimensional (2D) high TC superconductors, graphite intercalation compounds (GICs) are the most famous intercalation family, which are classified as typical electron-phonon mediated superconductors. We show unambiguous experimental facts that BaC 6 , the superconductivity of which has been missing for many years so far among various alkaline earth metal (Ca, Sr, and Ba) intercalted GICs, exhibits superconductivity at TC=65 mK . By adding this finding as the additional experimental point, a complete figure displaying the relationship between TC and interlayer distance (d ) for GICs is now provided, and their possible superconducting mechanisms raised so far are revisited. The present study settles a long-running debate between theories and experiments on the superconductivity in the first stage GICs.

  3. Technological hurdles to the application of intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1988-01-01

    Before intercalated graphite fibers can be developed as an effective power material, there are several technological hurdles which must be overcome. These include the environmental stability, homogeneity and bulk properties, connection procedures, and costs. Strides were made within the last several years in stability and homogeneity of intercalated graphite fibers. Bulk properties and connection procedures are areas of active research now. Costs are still prohibitive for all but the most demanding applications. None of these problems, however, appear to be unsolvable, and their solution may result in wide spread GOC application. The development of a relatively simple technology application, such as EMI shielding, would stimulate the solution of scale-up problems. Once this technology is developed, then more demanding applications, such as power bus bars, may be possible.

  4. Intercalated graphite fiber composites as EMI shields in aerospace structures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1990-01-01

    The requirements for electromagnetic interference (EMI) shielding in aerospace structures are complicated over that of ground structures by their weight limitations. As a result, the best EMI shielding materials must blend low density, high strength, and high elastic modulus with high shielding ability. In addition, fabrication considerations including penetrations and joints play a major role. The EMI shielding properties are calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compared to preliminary experimental results and to shields made from aluminum. Calculations indicate that EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding properties alone.

  5. Intercalated graphite fiber composites as EMI shields in aerospace structures

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1992-01-01

    The requirements for electromagnetic interference (EMI) shielding in aerospace structures are more complicated than those for ground structures because of their weight limitations. As a result, the best EMI shielding materials must combine low density, high strength, and high elastic modulus with high shielding ability. EMI shielding characteristics were calculated for shields formed from pristine and intercalated graphite fiber/epoxy composites and compare to preliminary experimental results for these materials and to the characteristics of shields made from aluminum. Calculations indicate that effective EMI shields could be fabricated from intercalated graphite composites which would have less than 12 percent of the mass of conventional aluminum shields, based on mechanical properties and shielding characteristics alone.

  6. Poly(pyrrole)/MoS{sub 2} intercalation compounds

    SciTech Connect

    Wang, L.; Kanatzidis, M.G.

    1995-12-31

    It is known that polymer/MoS{sub 2} intercalation compounds can be prepared through methods such as polymerizing intercalated monomers in MoS{sub 2} or mixing a polymer solution with MoS{sub 2} single layers suspended in water. The latter method is easy to perform, but can only be applied to soluble polymers. We have developed an in-situ polymerization-encapsulation method which was used to insert poly(pyrrole), an insoluble conjugated polymer, into MoS{sub 2}. Synthesis, characterization and electrical properties of the poly(pyrrole)/MoS{sub 2} materials, prepared by this method, will be presented and compared with other related lamellar systems.

  7. Controlled release of donepezil intercalated in smectite clays.

    PubMed

    Park, Jin Kuen; Choy, Young Bin; Oh, Jae-Min; Kim, Ju Young; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-07-01

    The inorganic-organic hybrid for a drug delivery system was successfully realized by intercalating donepezil molecules into smectite clays (laponite XLG, saponite, and montmorillonite). According to the powder XRD patterns, TG profiles, and FT-IR spectra, it was confirmed that donepezil molecules were well stabilized in the interlayer space of clay via mono or double layer stacking. The adsorption amount and molecular structure of donepezil appeared to depend on the cation exchange capacity of the clay, which in turn, tailored the drug release patterns. Especially in the presence of a bulky cationic polymer (Eudragit E-100) in the release media, the release rate was found to be improved due to its effective replacement with intercalated donepezil molecules. Therefore, to formulate a complete drug delivery system, the hybrids were coated with Eudragit E-100 using a spray dryer, which also showed great enhancement in the release rate during a short period of time (180min). PMID:18502063

  8. INTERCALATION OF TRICHLOROETHENE BY SEDIMENT-ASSOCIATED CLAY MINERALS

    PubMed Central

    Matthieu, D.E.; Brusseau, M.L.; Johnson, G.R.; Artiola, J.L.; Bowden, M.L.; Curry, J.E.

    2012-01-01

    The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site in Tucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer d-spacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (~26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment. PMID:22921434

  9. Controlling the photoconductivity: Graphene oxide and polyaniline self assembled intercalation

    NASA Astrophysics Data System (ADS)

    Vempati, Sesha; Ozcan, Sefika; Uyar, Tamer

    2015-02-01

    We report on controlling the optoelectronic properties of self-assembled intercalating compound of graphene oxide (GO) and HCl doped polyaniline (PANI). Optical emission and X-ray diffraction studies revealed a secondary doping phenomenon of PANI with -OH and -COOH groups of GO, which essentially arbitrate the intercalation. A control on the polarity and the magnitude of the photoresponse (PR) is harnessed by manipulating the weight ratios of PANI to GO (viz., 1:1.5 and 1:2.2 are abbreviated as PG1.5 and PG2.2, respectively), where ±PR = 100(RDark - RUV-Vis)/RDark and R corresponds to the resistance of the device in dark or UV-Vis illumination. To be precise, the PR from GO, PANI, PG1.5, and PG2.2 are +34%, -111%, -51%, and +58%, respectively.

  10. Graphene Made by Mechanical Exfoliation of Graphite Intercalation Compound

    NASA Astrophysics Data System (ADS)

    Fukada, Seiya; Shintani, Yumi; Shimomura, Midori; Tahara, Fumiya; Yagi, Ryuta

    2012-08-01

    We report a method of making few-layer graphene flakes by mechanically exfoliating SbCl5-graphite intercalation compounds (GICs). The number of layers of exfoliated graphene flakes had a particular distribution relevant to the stage structure of the GICs. The carrier doping of the few-layer graphene flakes was about two orders of magnitude smaller than that expected from the stoichiometry of the GICs. The measured electric mobility was comparable to that made from pristine graphite.

  11. Synthesis, Characterization, and Intercalation of Vanadyl Phosphate Modified with Manganese

    NASA Astrophysics Data System (ADS)

    Richtrová, Klára; Votinský, Jiří; Kalousová, Jaroslava; Beneš, Ludvík.; Zima, Vítěslav

    1995-05-01

    A yellow-brown crystalline solid, stable in air and having a variable composition of [Mn(H 2O] x(VO) 1- xPO 4 · 2H 2O (0 ≤ x ≤ 0.25), has been prepared by the reaction of solid V 2O 5 with a bolling aqueous solution of H 3PO 4 and KMnO 4. The elementary cell of this compound is tetragonal (space symmetry group either P4/ n or P 4/ nmm) with the following parameters for x = 0.25: a = 0.62034 nm, c = 1.3814 nm, V = 0.51359 nm 3, Z = 4, Mr = 199.44, Dcalc = 2.492 g/cm 3, and Dexp = 2.52 g/cm 3. The magnetic behavior of this substance indicates the presence of manganese atoms at the oxidation level of III. The paramagnetic centers formed by the Mn III atoms are not markedly magnetically coupled. The structure of the compound is probably derived from the original layered lattice of vanadyl phosphate hydrate VOPO 4 · 2H 2O by replacement of at most one quarter of the vanadyl groups (V VO) 3+ by [Mn III(H 2O)] 3+ groups. Upon being heated, the substance forms a monohydrate at first, then the anhydrous salt forms, and finally the water coordinated with manganese atoms escapes. The compound can be intercalated with foreign molecules and ions in the same way as vanadyl phosphate, and the results of intercalation experiments with methanol, ethanol, 1-propanol, l-butanol, 1-butylamine, 1-octylamine, formic acid, acetic acid, and pyridine, as well as those of oxidation-reduction intercalation with a solution of sodium iodide in acetone, are presented. The experimental conditions of the intercalations are described. The layered complexes formed have been identified by powder X-ray structure analysis, thermogravimetry, differential thermal analysis, and infrared absorption spectroscopy.

  12. Exfoliation and intercalation of montmorillonite by small peptides

    PubMed Central

    Block, Karin A.; Trusiak, Adrianna; Katz, Al; Alimova, Alexandra; Wei, Hui; Gottlieb, Paul; Steiner, Jeffrey C.

    2015-01-01

    Understanding structural changes in clay minerals induced by complexation with organic matter is relevant to soil science and agricultural applications. In this study, the effect of peptide storage in montmorillonite and the thermal stability of peptide-clay complexes was examined through characterization by X-ray diffraction (XRD), electron microscopy, UV absorption, and thermogravimetric analysis (TGA). XRD analysis of small peptide-montmorillonite clay complexes produced profiles consisting of reflections associated with the smectite 001 reflection and related peaks similar to that produced by a mixed layer clay mineral structure. Shifts in higher order diffraction maxima were attributed to disorder caused by the intercalation with the peptides. Increasing peptide concentrations resulted in greater shifts towards smaller 2θ from 6.37° (1.39 nm) to 5.45° (1.62 nm) as the interlayer space expanded. The expansion was accompanied by broadening of the 001 reflection (FWHM increases from 0.51 to 1.22° 2θ). The XRD line broadening was interpreted as caused by poorer crystallinity resulting from intercalation and tactoid exfoliation. SEM images revealed montmorillonite platelets with upwardly rolled edges that tend toward cylindrical structures with the production of tubules. High-resolution TEM images revealed bending of montmorillonite platelets, confirming exfoliation. The distribution of basal spacings in the micrographs was determined from the spatial frequencies obtained by Fourier analysis of density profiles. The distribution indicated the presence of discrete coherent crystallite domains. XRD and TGA results indicated that higher peptide concentrations resulted in a greater fraction of intercalated peptides and that surface adsorption of peptides mediated intercalation. Therefore, higher peptide concentration led to more stable organoclay complexes. However, UV absorption and TGA found that peptide adsorption onto montmorillonite had a finite limit at

  13. Synthesis and characterization of intercalated few-layer graphenes

    NASA Astrophysics Data System (ADS)

    Sato, Shogo; Ichikawa, Hiroaki; Iwata, Nobuyuki; Yamamoto, Hiroshi

    2014-02-01

    Toward achieving room-temperature superconductivity, FeCl3-intercalated few-layer graphenes (FeCl3-FLGs) and Ca-intercalated few-layer graphenes (Ca-FLGs) were synthesized. FeCl3-FLGs were synthesized by the two-zone method and Ca-FLGs were synthesized using Ca-Li alloy. The Raman spectra of the FeCl3-FLGs showed a lower-intensity peak at 1607 cm-1 than that of the corresponding bare G. The peak at 1607 cm-1 suggested that the sample was stage 4-5 FeCl3-FLGs. The room-temperature electrical resistivity of FeCl3-FLGs was 2.65 × 10-5 Ω·m, which linearly decreased with decreasing temperature with a marked change occurring at approximately 200 K. From a XRD pattern of Ca-FLGs, we concluded that Ca is intercalated in FLGs. The room-temperature resistivity of Ca-FLGs was 3.45 × 10-5 Ω·m, which increased with decreasing temperature.

  14. Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

    NASA Technical Reports Server (NTRS)

    West, William C.; Whitacre, Jay F.; Leifer, Nicole; Greenbaum, Steve; Smart, Marshall; Bugga, Ratnakumar; Blanco, Mario; Narayanan, S. R.

    2007-01-01

    We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium-fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and B-11 nuclear magnetic resonance studies suggest that cointercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties.

  15. Ferric chloride graphite intercalation compounds prepared from graphite fluoride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1994-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp3 electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp2 electronic structure and are electrical conductors. They contain first stage FeCl3 intercalated graphite. Some of the products contain FeCl2*2H2O, others contain FeF3 in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearing of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol %), this new GIC deintercalates without losing its molecular structure. However, when the compounds are heated to 800 C in quartz tube, they lost most of its halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber. This iron-oxide-covered fiber may be useful in making carbon-fiber/ceramic-matrix composites with strong bonding at the fiber-ceramic interface.

  16. Ferrix Chloride-Graphite Intercalation Compounds Prepared From Graphite Flouride

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1995-01-01

    The reaction between graphite fluoride and ferric chloride was observed in the temperature range of 300 to 400 C. The graphite fluorides used for this reaction have an sp(sup 3) electronic structure and are electrical insulators. They can be made by fluorinating either carbon fibers or powder having various degrees of graphitization. Reaction is fast and spontaneous and can occur in the presence of air. The ferric chloride does not have to be predried. The products have an sp(sup 2) electronic structure and are electrical conductors. They contain first-stage FeCl3 intercalated graphite. Some of the products contain FeCl2 (center dot) 2H2O, others contain FeF3, in concentrations that depend on the intercalation condition. The graphite intercalated compounds (GIC) deintercalated slowly in air at room temperature, but deintercalated quickly and completely at 370 C. Deintercalation is accompanied by the disappearance of iron halides and the formation of rust (hematite) distributed unevenly on the fiber surface. When heated to 400 C in pure N2 (99.99 vol%), this new GIC deintercalates without losing its molecular structure. However, when the compounds are exposed to 800 C N2, in a quartz tube, they lost most of their halogen atoms and formed iron oxides (other than hematite), distributed evenly in or on the fiber.

  17. Manipulate the Doping of Graphene at Nanoscale with Intercalated Oxygen

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Luo, Hong; Liu, Lei; Gu, Gong; Stradi, Daniele; Brandbyge, Mads

    2015-03-01

    We have created nanoscale p- and n-doped graphene regions side by side, by partially removing the oxygen between the graphene and the Cu foil growth substrate intercalated upon elongated air exposure. The Cu foil surface is almost exclusively (100) oriented, and the removal of intercalated oxygen is by thermal annealing. Scanning tunneling microscopy (STM) reveals a 0.72 × 0.72 nm square superlattice in the single layer (1L) graphene/O/Cu(100) structure, assigned to be Cu(2√{ 2} × 2√{ 2})R45°-O, which has not been reported so far. Graphene with intercalated oxygen underneath it is p-doped while the surrounding graphene areas, directly in contact with the copper surface, are n-doped. Comparing the scanning tunneling spectra (STS) of the two types of regions, we show a charge transfer-induced shift of the electronic structure. Such a shift is also observed between p- and n-doped twisted bilayer (2L) graphene regions, where the van Hove singularity (vHS) peaks are used as markers to precisely determine the energy shift. Across the boundaries between the p- and n-doped regions, the shift of the electronic structure is spatially resolved, showing the vanishing and reappearance of the vHS peaks. The experimental observations are consistent with first-principles calculations.

  18. Electrochemical Intercalation of Lithium Ions into Carbon Nanotube Bundles

    NASA Astrophysics Data System (ADS)

    Allen, J. L.; Sumanasekera, G. U.; Rao, A. M.; Fang, S.; Eklund, P. C.

    1998-03-01

    We have investigated the electrochemical intercalation of lithium ions into ropes of single-walled carbon nanotubes (SWNTs) in a standard three electrode cell. The SWNT mat pressed onto a Pt plate was the working electrode. Lithium was used at both the counter and reference electrodes, and 1M LiAsF6 in ethylene carbonate:diethyl carbonate (1:1 by volume) served as the electrolyte. Raman spectra of the SWNTs were recorded in situ as a function of electrochemical charge using 514.5 nm excitation. During galvanostatic intercalation, we observed a relatively steep decrease in voltage until a plateau at around 1.2 V is reached. We attribute this initial decrease to the intercalation of lithium into SWNT and a concurrent electron doping of the SWNT π band. In the Raman spectrum, as the voltage reaches 1.2 V, the tangential mode frequency down shifted from 1593 cm-1 to 1591 cm-1 consistent with electron addition to the π^* band. We speculate that surface reactions of the lithium doped SWNT and the electrolyte are occuring during the plateau. During the evolution of the plateau, the Raman signal of the tangential mode gradually diminishes without further downshift of the its frequency and eventually disappears completely. Cyclic voltammograms show a minimum at around 1.2 V and peaks at around 0.7 V and 1.7 V. The origin of this structure is not presently understood.

  19. Sodium-Ion Intercalation Mechanism in MXene Nanosheets.

    PubMed

    Kajiyama, Satoshi; Szabova, Lucie; Sodeyama, Keitaro; Iinuma, Hiroki; Morita, Ryohei; Gotoh, Kazuma; Tateyama, Yoshitaka; Okubo, Masashi; Yamada, Atsuo

    2016-03-22

    MXene, a family of layered compounds consisting of nanosheets, is emerging as an electrode material for various electrochemical energy storage devices including supercapacitors, lithium-ion batteries, and sodium-ion batteries. However, the mechanism of its electrochemical reaction is not yet fully understood. Herein, using solid-state (23)Na magic angle spinning NMR and density functional theory calculation, we reveal that MXene Ti3C2Tx in a nonaqueous Na(+) electrolyte exhibits reversible Na(+) intercalation/deintercalation into the interlayer space. Detailed analyses demonstrate that Ti3C2Tx undergoes expansion of the interlayer distance during the first sodiation, whereby desolvated Na(+) is intercalated/deintercalated reversibly. The interlayer distance is maintained during the whole sodiation/desodiation process due to the pillaring effect of trapped Na(+) and the swelling effect of penetrated solvent molecules between the Ti3C2Tx sheets. Since Na(+) intercalation/deintercalation during the electrochemical reaction is not accompanied by any substantial structural change, Ti3C2Tx shows good capacity retention over 100 cycles as well as excellent rate capability. PMID:26891421

  20. Crystal structures of superconducting sodium intercalates of hafnium nitride chloride

    SciTech Connect

    Oro-Sole, J.; Frontera, C.; Beltran-Porter, D.; Van Tendeloo, G.; Fuertes, A. . E-mail: amparo.fuertes@icmab.es

    2006-05-25

    Sodium intercalation compounds of HfNCl have been prepared at room temperature in naphtyl sodium solutions in tetrahydrofuran and their crystal structure has been investigated by Rietveld refinement using X-ray powder diffraction data and high-resolution electron microscopy. The structure of two intercalates with space group R3-bar m and lattice parameters a=3.58131(6)A, c=57.752(6)A, and a=3.58791(8)A, c=29.6785(17)A is reported, corresponding to the stages 2 and 1, respectively, of Na{sub x}HfNCl. For the stage 2 phase an ordered model is presented, showing two crystallographically independent [HfNCl] units with an alternation of the Hf-Hf interlayer distance along the c-axis, according with the occupation by sodium atoms of one out of two van der Waals gaps. Both stages 1 and 2 phases are superconducting with critical temperatures between 20 and 24K, they coexist in different samples with proportions depending on the synthesis conditions, and show a variation in c spacing that can be correlated with the sodium stoichiometry. High-resolution electron microscopy images of the host and intercalated samples show bending of the HfNCl bilayers as well as stacking faults in some regions, which coexist in the same crystal with ordered domains.

  1. Intercalation of stable organic radicals into layered saponite clay.

    PubMed

    Hemme, Wilhelm L; Fujita, Wataru; Awaga, Kunio; Eckert, Hellmut

    2009-10-14

    2-(3- and 4-N-methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-N-oxide (abbreviated as m- and p-MPYNN), the butyl derivative (m- and p-BuPYNN), 4-(N-ethylammonium)-2,2,5,5-tetramethylpiperidin-1-oxyl (ETEP) and N,N,N',N'-Tetramethyl-1,4-phenylenediamine radical cation (TMPD(+)) have been successfully intercalated into saponite clay. The amount of intercalated material has been determined via UV/VIS spectroscopy, elemental analysis and EPR spectroscopy, and the expansion of the layer distance from approximately 12.0 to ca. 15 A has been measured by X-ray powder diffraction. The magnetic properties of these materials, which result from the interplay of the modified intermolecular interactions between the guest species, and the additional interaction with the host lattice, have been characterized by magnetic susceptibility, EPR and solid state NMR measurements. While the (29)Si and (27)Al NMR spectra show little influence of the radical species on the local structural environments of the nuclei in the host lattice, the guest-host interaction manifests itself in significant line-broadening and (in some cases) resonance displacements of the (1)H NMR signals belonging to the molecular radical cations. In the case of TMPD(+) intercalates, the NMR and EPR data indicate predominant radical dimerization within the interlayer space. PMID:19771362

  2. Non-oxidative intercalation and exfoliation of graphite by Brønsted acids

    NASA Astrophysics Data System (ADS)

    Kovtyukhova, Nina I.; Wang, Yuanxi; Berkdemir, Ayse; Cruz-Silva, Rodolfo; Terrones, Mauricio; Crespi, Vincent H.; Mallouk, Thomas E.

    2014-11-01

    Graphite intercalation compounds are formed by inserting guest molecules or ions between sp2-bonded carbon layers. These compounds are interesting as synthetic metals and as precursors to graphene. For many decades it has been thought that graphite intercalation must involve host-guest charge transfer, resulting in partial oxidation, reduction or covalent modification of the graphene sheets. Here, we revisit this concept and show that graphite can be reversibly intercalated by non-oxidizing Brønsted acids (phosphoric, sulfuric, dichloroacetic and alkylsulfonic acids). The products are mixtures of graphite and first-stage intercalation compounds. X-ray photoelectron and vibrational spectra indicate that the graphene layers are not oxidized or reduced in the intercalation process. These observations are supported by density functional theory calculations, which indicate a dipolar interaction between the guest molecules and the polarizable graphene sheets. The intercalated graphites readily exfoliate in dimethylformamide to give suspensions of crystalline single- and few-layer graphene sheets.

  3. Magnetic field effects on superconductivity in alkali metal intercalates of MoS2

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Flood, D. J.; Wagoner, D. E.; Somoano, R. B.; Rembaum, A.

    1972-01-01

    The effects of a magnetic field on the superconducting transition in MoS2 intercalated with potassium and sodium were studied. It was found that the potassium intercalated MoS2 has better properties in a magnetic field. In zero magnetic field the transition to superconductivity begins near 6.4 K. Diagrams of the basic circuitry for superconducting transition studies, and charts showing critical magnetic field versus critical temperature for the intercalated MoS2 are included.

  4. High field superconductivity in alkali metal intercalates of MoS2

    NASA Technical Reports Server (NTRS)

    Woollam, J. A.; Flood, D. J.; Wagoner, D. E.; Somoano, R. B.; Rembaum, A.

    1973-01-01

    In the search for better high temperature, high critical field superconductors, a class of materials was found which have layered structures and can be intercalated with various elements and compounds. Since a large number of compounds can be formed, intercalation provides a method of control of superconducting properties. They also provide the possible medium for excitonic superconductivity. Results of magnetic field studies are presented on alkali metal (Na, K, Rb, and Cs) intercalated MoS2 (2H polymorph).

  5. Superconductivity in Pd-intercalated charge-density-wave rare earth poly-tellurides RETe n

    NASA Astrophysics Data System (ADS)

    He, J. B.; Wang, P. P.; Yang, H. X.; Long, Y. J.; Zhao, L. X.; Ma, C.; Yang, M.; Wang, D. M.; Shangguan, X. C.; Xue, M. Q.; Zhang, P.; Ren, Z. A.; Li, J. Q.; Liu, W. M.; Chen, G. F.

    2016-06-01

    Charge density waves (CDWs) are periodic modulations of the conduction electron density in solids, which are generally considered to remove electrons from the Fermi level, and thus preclude a superconducting state. However, in a variety of CDW materials, such as the prototypical transition metal chalcogenides, superconductivity has also been observed at very low temperature (Yokoya et al 2001 Science 294 2518; Morosan et al 2006 Nat. Phys. 2 544; Kiss et al 2007 Nat. Phys. 3 720), in which, although the two electronic correlated states are believed to occur in different parts of Fermi surface sheets derived mainly from chalcogen p-states and transition metal d-states, the nature of the relationship between them has not yet been unambiguously determined. Here we report the discovery of superconductivity in Pd-intercalated RETe n (RE = rare earth; n = 2.5, 3) CDW systems, in which the chalcogen layers alone are responsible for both superconductivity and CDW instability. Our finding could provide an ideal model system for comprehensive study of the interplay between CDW and superconductivity due to the remarkable simplicity of the electronic structure of Te planes.

  6. Nickel hexacyanoferrate, a versatile intercalation host for divalent ions from nonaqueous electrolytes

    NASA Astrophysics Data System (ADS)

    Lipson, Albert L.; Han, Sang-Don; Kim, Soojeong; Pan, Baofei; Sa, Niya; Liao, Chen; Fister, Timothy T.; Burrell, Anthony K.; Vaughey, John T.; Ingram, Brian J.

    2016-09-01

    New energy storage chemistries based on Mg ions or Ca ions can theoretically improve both the energy density and reduce the costs of batteries. To date there has been limited progress in implementing these systems due to the challenge of finding a high voltage high capacity cathode that is compatible with an electrolyte that can plate and strip the elemental metal. In order to accelerate the discovery of such a system, model systems are needed that alleviate some of the issues of incompatibility. This report demonstrates the ability of nickel hexacyanoferrate to electrochemically intercalate Mg, Ca and Zn ions from a nonaqueous electrolyte. This material has a relatively high insertion potential and low overpotential in the electrolytes used in this study. Furthermore, since it is not an oxide based cathode it should be able to resist attack by corrosive electrolytes such as the chloride containing electrolytes that are often used to plate and strip magnesium. This makes it an excellent cathode for use in developing and understanding the complex electrochemistry of multivalent ion batteries.

  7. Tuning the properties of polymer bulk heterojunction solar cells by adjusting fullerene size to control intercalation

    SciTech Connect

    Cates, N.C.

    2010-02-24

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells.

  8. Solar flare discovery

    NASA Technical Reports Server (NTRS)

    Hudson, Hugh S.

    1987-01-01

    This paper considers the discoveries that have appreciably changed our understanding of the physics of solar flares. A total of 42 discoveries from all disciplines, ranging from Galileo's initial observation of faculae to the recent discovery of strong limb brightening in 10-MeV gamma-radiation, are identified. The rate of discovery increased dramatically over the past four decades as new observational tools became available. The assessment of significance suggests that recent discoveries -though more numerous - are individually less significant; perhaps this is because the minor early discoveries tend to be taken for granted.

  9. The intercalated nuclear complex of the primate amygdala.

    PubMed

    Zikopoulos, Basilis; John, Yohan J; García-Cabezas, Miguel Ángel; Bunce, Jamie G; Barbas, Helen

    2016-08-25

    The organization of the inhibitory intercalated cell masses (IM) of the primate amygdala is largely unknown despite their key role in emotional processes. We studied the structural, topographic, neurochemical and intrinsic connectional features of IM neurons in the rhesus monkey brain. We found that the intercalated neurons are not confined to discrete cell clusters, but form a neuronal net that is interposed between the basal nuclei and extends to the dorsally located anterior, central, and medial nuclei of the amygdala. Unlike the IM in rodents, which are prominent in the anterior half of the amygdala, the primate inhibitory net stretched throughout the antero-posterior axis of the amygdala, and was most prominent in the central and posterior extent of the amygdala. There were two morphologic types of intercalated neurons: spiny and aspiny. Spiny neurons were the most abundant; their somata were small or medium size, round or elongated, and their dendritic trees were round or bipolar, depending on location. The aspiny neurons were on average slightly larger and had varicose dendrites with no spines. There were three non-overlapping neurochemical populations of IM neurons, in descending order of abundance: (1) Spiny neurons that were positive for the striatal associated dopamine- and cAMP-regulated phosphoprotein (DARPP-32+); (2) Aspiny neurons that expressed the calcium-binding protein calbindin (CB+); and (3) Aspiny neurons that expressed nitric oxide synthase (NOS+). The unique combinations of structural and neurochemical features of the three classes of IM neurons suggest different physiological properties and function. The three types of IM neurons were intermingled and likely interconnected in distinct ways, and were innervated by intrinsic neurons within the amygdala, or by external sources, in pathways that underlie fear conditioning and anxiety. PMID:27256508

  10. High-Temperature Intercalated Graphite Fiber Conductors Fabricated

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    2002-01-01

    Composites of intercalated graphite fibers show promise to significantly reduce the weight of electromagnetic interference shielding in spacecraft and aircraft. Bromine intercalated pitch-based fibers have been among the most heavily studied systems because of their attractive electrical and thermal conductivities and their stability over a wide range of environmental conditions. Previous studies found that the resistivity of bromineintercalated graphite fibers began to increase when the fibers were exposed to temperatures in excess of about 200 C in air for long periods of time. If the temperature was as high as 450 C, the resistivity increased dramatically within a few hours. It remained unclear, however, whether the increase was due to deintercalation of the bromine or to air oxidation of the fibers. Studies were initially directed toward determining the temperature at which bromine would deintercalate from the fibers, and perhaps become a hazard to both personnel and equipment. So the mass of bromine-intercalated graphite fibers was carefully monitored as it was heated in an inert atmosphere, since the fibers are known to oxidize at a lower temperature than they deintercalate. What was found was that the fibers, which are about 18-wt% bromine, did not lose any appreciable mass even at temperatures approaching 1000 C. X-ray diffraction studies showed that there were also no changes in the overall structure of the compound. Resistivity measurements indicated that there is some slight degradation in the electronic structure, in that the resistivity increased by a few percent. Overall, the results show that these materials may be suitable for applications at temperatures at least this high, provided oxygen is excluded. This may enable their use in carbon-ceramic, and perhaps even carbon-carbon composites.

  11. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    SciTech Connect

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J.

    1994-12-31

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer.

  12. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol.

    PubMed

    Worcester, D L; Hamacher, K; Kaiser, H; Kulasekere, R; Torbet, J

    1996-01-01

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer. PMID:9031514

  13. Synthesis, characterization, and intercalation of vanadyl phsophate modified with manganese

    SciTech Connect

    Richtrova, K.; Votinsky, J.; Kalousova, J.

    1995-05-01

    A yellow-brown crystalline solid, stable in air and having a variable composition of [Mn(H{sub 2}O)]{sub x}(VO){sub 1-x}PO{sub 4}{center_dot}2H{sub 2}O (0 {le} x {le} 0.25), has been prepared by the reaction of solid V{sub 2}O{sub 5} with a boiling aqueous solution of H{sub 3}PO{sub 4} and KMnO{sub 4}. The elementary cell of this compound is tetragonal (space symmetry group either P4/n or P4/nmm) with the following parameters for x = 0.25; a = 0.62034 nm, c = 1.3813 nm, V = 0.51359 nm{sup 3}, Z = 4, M{sub r} = 199.44, D{sub calc} = 2.492 g/cm{sup 3}, and D{sub exp} = 2.52 g/cm{sup 3}. The magnetic behavior of this substance indicates the presence of manganese atoms at the oxidation level of III. The paramagnetic centers formed by the Mn{sub III} atoms are not markedly magnetically coupled. The structure of the compound is probably derived from the original layered lattice of vanadyl phosphate hydrate VOPO{sub 4}{center_dot}2H{sub 2}O by replacement of at most one quarter of the vanadyl groups (V{sup V}O){sup 3+} by [Mn{sup III}(H{sub 2}O)]{sup 3+} groups. Upon being heated, the substance forms a monohydrate at first, then the anhydrous salt forms, and finally the water coordinated with manganese atoms escapes. The compound can be intercalated with foreign molecules and ions in the same way as vanadyl phosphate, and the results of intercalation experiments with methanol, ethanol, 1-propanol, 1-butanol, 1-butylamine, 1-octylamine, formic acid, acetic acid, and pyridine, as well as those of oxidation-reduction intercalation with a solution of sodium intercalations are described. The layered complexes formed have been identified by powder X-ray structure analysis, thermogravimetry, differential thermal analysis, and infrared absorption spectroscopy.

  14. C-13 nuclear magnetic resonance in graphite intercalation compounds

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Resing, H. A.

    1985-01-01

    The C-13 NMR chemical shifts of graphite intercalation compounds have been calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about - 140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal-conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

  15. The 13C nuclear magnetic resonance in graphite intercalation compounds

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Resing, H. A.

    1985-01-01

    The (13)C NMR chemical shifts of graphite intercalation compounds were calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about -140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

  16. Understanding Li diffusion in Li-intercalation compounds.

    PubMed

    Van der Ven, Anton; Bhattacharya, Jishnu; Belak, Anna A

    2013-05-21

    Intercalation compounds, used as electrodes in Li-ion batteries, are a fascinating class of materials that exhibit a wide variety of electronic, crystallographic, thermodynamic, and kinetic properties. With open structures that allow for the easy insertion and removal of Li ions, the properties of these materials strongly depend on the interplay of the host chemistry and crystal structure, the Li concentration, and electrode particle morphology. The large variations in Li concentration within electrodes during each charge and discharge cycle of a Li battery are often accompanied by phase transformations. These transformations include order-disorder transitions, two-phase reactions that require the passage of an interface through the electrode particles, and structural phase transitions, in which the host undergoes a crystallographic change. Although the chemistry of an electrode material determines the voltage range in which it is electrochemically active, the crystal structure of the compound often plays a crucial role in determining the shape of the voltage profile as a function of Li concentration. While the relationship between the voltage profile and crystal structure of transition metal oxide and sulfide intercalation compounds is well characterized, far less is known about the kinetic behavior of these materials. For example, because these processes are especially difficult to isolate experimentally, solid-state Li diffusion, phase transformation mechanisms, and interface reactions remain poorly understood. In this respect, first-principles statistical mechanical approaches can elucidate the effect of chemistry and crystal structure on kinetic properties. In this Account, we review the key factors that govern Li diffusion in intercalation compounds and illustrate how the complexity of Li diffusion mechanisms correlates with the crystal structure of the compound. A variety of important diffusion mechanisms and associated migration barriers are sensitive to

  17. Lithium Intercalation in Core-Shell Materials-Theoretical Analysis

    SciTech Connect

    Suthar, B; Subramanian, VR

    2014-03-04

    Core-shell composite structures are potential candidates for Li-ion battery electrodes as they can take advantage of materials with higher energy density and materials with higher cyclability. This paper derives an analytical solution for isotropic 1-dimensional diffusion with galvanostatic boundary condition in composite slab, cylinder and sphere using separation of variables method. A general interfacial condition has been used to represent the dynamics at the interface of the composite material rendering the solution useful for wide variety of battery materials. Using the derived analytical solution for diffusion, intercalation induced stresses were estimated for spherical core-shell materials. (C) 2014 The Electrochemical Society. All rights reserved.

  18. Lithium intercalation reaction into the Keggin type polyoxomolybdates

    NASA Astrophysics Data System (ADS)

    Sonoyama, Noriyuki; Suganuma, Yoshiaki; Kume, Tomohiro; Quan, Zhen

    The electrochemical property of Keggin type hetero polyoxomolybdate K 3[PMo 12O 40] (KPM) as the cathode electrode material for lithium battery was examined. KPM showed charge-discharge performance in the potential region from 4.2 V to 1.5 V with capacity of over 200 mAh g -1. From the result of the ex situ XRD measurement, it is presumed that the electrochemical reaction of KPM proceeds via the lithium (de-)intercalation. The cycle performance of KPM is largely dependent on the charge-discharge potential range. The capacity fade caused by deep discharging seems to be concerned to the < to ® isomerization of KPM.

  19. Structural and electronic properties of sodium-intercalated C60

    NASA Astrophysics Data System (ADS)

    Rosseinsky, M. J.; Murphy, D. W.; Fleming, R. M.; Tycko, R.; Ramirez, A. P.; Siegrist, T.; Dabbagh, G.; Barrett, S. E.

    1992-04-01

    The synthesis and initial characterization of bulk Na(x)C60 (x = 2-6) and mixed alkali phase Na2AC60 (where A is K, Rb, or Cs) are reported. All of these phases have intercalated fcc structures. The Na6C60 structure has a Na4 cluster centered on the octahedral site. The Na2AC60 compounds superconduct for the larger A cations, but a crossover to nonsuperconducting behavior occurs with decreasing cation size and correlates with a minimum in the unit cell volume.

  20. Modeling of alkyl quaternary ammonium cations intercalated into montmorillonite lattice

    SciTech Connect

    Daoudi, El Mehdi; Boughaleb, Yahia; El Gaini, Layla; Meghea, Irina; Bakasse, Mina

    2013-05-15

    Highlights: ► The modification of montmorillonites by three surfactants increases the basal spacing. ► The model proposed show a bilayer conformation for the surfactant ODTMA. ► The DODMA and TOMA surfactants adopt a paraffin type arrangement. ► Behavior of surfactants in interlayer space was confirmed by TGA and ATR analysis. - Abstract: The objective of this work was to study the conformation of the quaternary ammonium cations viz., octadecyl trimethyl ammonium (ODTMA), dioctadecyl dimethyl ammonium (DMDOA) and trioctadecyl methyl ammonium (TOMA) intercalated within montmorillonite. The modified montmorillonite was characterized by X-ray diffraction in small angle (SAXS), thermal analysis (TGA) and infrared spectroscopy of attenuated total reflection (ATR). The modification of organophilic montmorillonites by the three surfactants ODTMA, DMDOA and TOMA increases the basal spacing from their respective intercalated distances of 1.9 nm, 2.6 nm and 3.4 nm respectively. The increase in the spacing due to the basic organic modification was confirmed by the results of thermal analysis (TGA) and infrared spectroscopy (ATR), and also supported by theoretical calculations of longitudinal and transversal chain sizes of these alkyl quaternary ammonium cations.

  1. Two Dimensional Ice crystals intercalated between graphene and mica

    NASA Astrophysics Data System (ADS)

    Bampoulis, Pantelis; Siekman, Martin H.; Kooij, E. Stefan; Lohse, Detlef; Zandvliet, Harold J. W.; Poelsema, Bene; Mesa+ Institute for Nanotechnology Team

    The physics and chemistry of the interfacial contact between water and solid surfaces are of the highest fundamental and practical interest in environmental sciences, many biological systems and corrosion effects. Water intercalated between graphene and mica has recently received much interest, even amplified by intriguing intercalation effects and by the evolution of fractals. These confined water layers are argued to be ice-like at room temperature. Due to its good thermal isolation from the environment, as a result of poor perpendicular heat transport through both mica and graphene, this system is uniquely suited for studying the consequences of heat transport, due to latent heat effects, during growth and melting of 2D ice crystals. The enigmatic growth of ice crystals poses a longstanding fundamental problem and its solution is possibly hidden in influences of heat and particle transport. Indeed, we find that heat and particle transport play a crucial role in the growth of ice crystals under high-temperature and high supersaturation conditions.

  2. Membrane-intercalating conjugated oligoelectrolytes: impact on bioelectrochemical systems.

    PubMed

    Yan, Hengjing; Catania, Chelsea; Bazan, Guillermo C

    2015-05-20

    Conjugated oligoelectrolytes (COEs), molecules that are defined by a π-delocalized backbone and terminal ionic pendant groups, have been previously demonstrated to effectively reduce charge-injection/extraction barriers at metal/organic interfaces in thin-film organic-electronic devices. Recent studies demonstrate a spontaneous affinity of certain COEs to intercalate into, and align within, lipid bilayers in an ordered orientation, thereby allowing modification of membrane properties and the functions of microbes in bioelectrochemical and photosynthetic systems. Several reports have provided evidence of enhanced current generation and bioproduction. Mechanistic approaches suggest that COEs influence microbial extracellular electron transport to abiotic electrode surfaces via more than one proposed pathway, including direct electron transfer and meditated electron transfer. Molecular dynamics simulations as a function of molecular structure suggest that insertion of cationic COEs results in membrane thinning as the lipid phosphate head groups are drawn toward the center of the bilayer. Since variations in molecular structures, especially the length of the conjugated backbone, distribution of ionic groups, and hydrophobic substitutions, show an effect on their antimicrobial properties, preferential cell localization, and microbial selection, it is promising to further design novel membrane-intercalating molecules based on COEs for practical applications, including energy generation, environmental remediation, and antimicrobial treatment. PMID:25846107

  3. Electron Beam Irradiated Intercalated CNT Yarns For Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Waters, Deborah L.; Gaier, James R.; Williams, Tiffany S.; Lopez Calero, Johnny E.; Ramirez, Christopher; Meador, Michael A.

    2015-01-01

    Multi-walled CNT yarns have been experimentally and commercially created to yield lightweight, high conductivity fibers with good tensile properties for application as electrical wiring and multifunctional tendons. Multifunctional tendons are needed as the cable structures in tensegrity robots for use in planetary exploration. These lightweight robust tendons can provide mechanical strength for movement of the robot in addition to power distribution and data transmission. In aerospace vehicles, such as Orion, electrical wiring and harnessing mass can approach half of the avionics mass. Use of CNT yarns as electrical power and data cables could reduce mass of the wiring by thirty to seventy percent. These fibers have been intercalated with mixed halogens to increase their specific electrical conductivity to that near copper. This conductivity, combined with the superior strength and fatigue resistance makes it an attractive alternative to copper for wiring and multifunctional tendon applications. Electron beam irradiation has been shown to increase mechanical strength in pristine CNT fibers through increased cross-linking. Both pristine and intercalated CNT yarns have been irradiated using a 5-megavolt electron beam for various durations and the conductivities and tensile properties will be discussed. Structural information obtained using a field emission scanning electron microscope, energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy will correlate microstructural details with bulk properties.

  4. Resistivity of pristine and intercalated graphite fiber epoxy composites

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Hambourger, Paul D.; Slabe, Melissa E.

    1989-01-01

    Laminar composites were fabricated from pristine and bromine intercalated Amoco P-55, P-75, and P-100 graphite fibers and Hysol-Grafil EAG101-1 film epoxy. The thickness and r.f. eddy current resistivity of several samples were measured at grid points and averaged point by point to obtain final values. Although the values obtained this way have high precision (less than 3 percent deviation), the resistivity values appear to be 20 to 90 percent higher than resistivities measured on high aspect ratio samples using multi-point techniques, and by those predicted by theory. The temperature dependence of the resistivity indicates that the fibers are neither damaged nor deintercalated by the composite fabrication process. The resistivity of the composites is a function of sample thickness (i.e., resin content). Composite resistivity is dominated by fiber resistivity, so lowering the resistivity of the fibers, either through increased graphitization or intercalation, results in a lower composite resistivity. A modification of the simple rule of mixtures model appears to predict the conductivity of high aspect ratio samples measured along a fiber direction, but a directional dependence appears which is not predicted by the theory. The resistivity of these materials is clearly more complex than that of homogeneous materials.

  5. NLP-1: a DNA intercalating hypoxic cell radiosensitizer and cytotoxin

    SciTech Connect

    Panicucci, R.; Heal, R.; Laderoute, K.; Cowan, D.; McClelland, R.A.; Rauth, A.M.

    1989-04-01

    The 2-nitroimidazole linked phenanthridine, NLP-1 (5-(3-(2-nitro-1-imidazoyl)-propyl)-phenanthridinium bromide), was synthesized with the rationale of targeting the nitroimidazole to DNA via the phenanthridine ring. The drug is soluble in aqueous solution (greater than 25 mM) and stable at room temperature. It binds to DNA with a binding constant 1/30 that of ethidium bromide. At a concentration of 0.5 mM, NLP-1 is 8 times more toxic to hypoxic than aerobic cells at 37 degrees C. This concentration is 40 times less than the concentration of misonidazole, a non-intercalating 2-nitroimidazole, required for the same degree of hypoxic cell toxicity. The toxicity of NLP-1 is reduced at least 10-fold at 0 degrees C. Its ability to radiosensitize hypoxic cells is similar to misonidazole at 0 degrees C. Thus the putative targeting of the 2-nitroimidazole, NLP-1, to DNA, via its phenanthridine group, enhances its hypoxic toxicity, but not its radiosensitizing ability under the present test conditions. NLP-1 represents a lead compound for intercalating 2-nitroimidazoles with selective toxicity for hypoxic cells.

  6. Methotrexate intercalated ZnAl-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  7. An intercalation-locked parallel-stranded DNA tetraplex

    PubMed Central

    Tripathi, Shailesh; Zhang, Daoning; Paukstelis, Paul J.

    2015-01-01

    DNA has proved to be an excellent material for nanoscale construction because complementary DNA duplexes are programmable and structurally predictable. However, in the absence of Watson–Crick pairings, DNA can be structurally more diverse. Here, we describe the crystal structures of d(ACTCGGATGAT) and the brominated derivative, d(ACBrUCGGABrUGAT). These oligonucleotides form parallel-stranded duplexes with a crystallographically equivalent strand, resulting in the first examples of DNA crystal structures that contains four different symmetric homo base pairs. Two of the parallel-stranded duplexes are coaxially stacked in opposite directions and locked together to form a tetraplex through intercalation of the 5′-most A–A base pairs between adjacent G–G pairs in the partner duplex. The intercalation region is a new type of DNA tertiary structural motif with similarities to the i-motif. 1H–1H nuclear magnetic resonance and native gel electrophoresis confirmed the formation of a parallel-stranded duplex in solution. Finally, we modified specific nucleotide positions and added d(GAY) motifs to oligonucleotides and were readily able to obtain similar crystals. This suggests that this parallel-stranded DNA structure may be useful in the rational design of DNA crystals and nanostructures. PMID:25628357

  8. Intercalation of cellulase enzyme into a hydrotalcite layer structure

    NASA Astrophysics Data System (ADS)

    Zou, N.; Plank, J.

    2015-01-01

    A new inorganic-organic hybrid material whereby cellulase enzyme is incorporated into a hydrotalcite type layered double hydroxide (LDH) structure is reported. The Mg2Al-cellulase-LDH was synthesized via co-precipitation from Mg/Al nitrate at pH=9.6. Characterization was performed using X-ray powder diffraction (XRD), small angle X-ray scattering (SAXS), elemental analysis, infrared spectroscopy (IR) and thermogravimetry (TG). From XRD and SAXS measurements, a d-value of ~5.0 nm was identified for the basal spacing of the Mg2Al-cellulase-LDH. Consequently, the cellulase enzyme (hydrodynamic diameter ~6.6 nm) attains a slightly compressed conformation when intercalated. Formation of the LDH hybrid was also confirmed via scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mg2Al-cellulase-LDH phases appear as ~20 nm thin foils which are intergrown to flower-like aggregates. Activity of the enzyme was retained after deintercalation from the Mg2Al-LDH framework using anion exchange. Accordingly, cellulase is not denatured during the intercalation process, and LDH presents a suitable host structure for time-controlled release of the biomolecule.

  9. Sulfuric Acid Intercalated Graphite Oxide for Graphene Preparation

    NASA Astrophysics Data System (ADS)

    Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

    2013-12-01

    Graphene has shown enormous potential for innovation in various research fields. The current chemical approaches based on exfoliation of graphite via graphite oxide (GO) are potential for large-scale synthesis of graphene but suffer from high cost, great operation difficulties, and serious waste discharge. We report a facile preparation of graphene by rapid reduction and expansion exfoliation of sulfuric acid intercalated graphite oxide (SIGO) at temperature just above 100°C in ambient atmosphere, noting that SIGO is easily available as the immediate oxidation descendent of graphite in sulfuric acid. The oxygenic and hydric groups in SIGO are mainly removed through dehydration as catalyzed by the intercalated sulfuric acid (ISA). The resultant consists of mostly single layer graphene sheets with a mean diameter of 1.07 μm after dispersion in DMF. This SIGO process is reductant free, easy operation, low-energy, environmental friendly and generates graphene with low oxygen content, less defect and high conductivity. The provided synthesis route from graphite to graphene via SIGO is compact and readily scalable.

  10. Sulfuric Acid Intercalated Graphite Oxide for Graphene Preparation

    PubMed Central

    Hong, Yanzhong; Wang, Zhiyong; Jin, Xianbo

    2013-01-01

    Graphene has shown enormous potential for innovation in various research fields. The current chemical approaches based on exfoliation of graphite via graphite oxide (GO) are potential for large-scale synthesis of graphene but suffer from high cost, great operation difficulties, and serious waste discharge. We report a facile preparation of graphene by rapid reduction and expansion exfoliation of sulfuric acid intercalated graphite oxide (SIGO) at temperature just above 100°C in ambient atmosphere, noting that SIGO is easily available as the immediate oxidation descendent of graphite in sulfuric acid. The oxygenic and hydric groups in SIGO are mainly removed through dehydration as catalyzed by the intercalated sulfuric acid (ISA). The resultant consists of mostly single layer graphene sheets with a mean diameter of 1.07 μm after dispersion in DMF. This SIGO process is reductant free, easy operation, low-energy, environmental friendly and generates graphene with low oxygen content, less defect and high conductivity. The provided synthesis route from graphite to graphene via SIGO is compact and readily scalable. PMID:24310650

  11. Anion-Intercalating Cathodes for High-Energy-Density Cells

    NASA Technical Reports Server (NTRS)

    West, William

    2006-01-01

    A report discusses physicochemical issues affecting a fluoride-intercalating cathode that operates in conjunction with a lithium ion-intercalating anode in a rechargeable electrochemical cell described in a cited prior report. The instant report also discusses corresponding innovations made in solvent and electrolyte compositions since the prior report. The advantages of this cell, relative to other lithium-ion-based cells, are said to be greater potential (5 V vs. 4 V), and greater theoretical cathode specific capacity (0.9 to 2.2 A-h/g vs. about 0.18 A-h/g). The discussion addresses a need for the solvent to be unreactive toward the lithium anode and to resist anodic oxidation at potentials greater than about 4.5 V vs. lithium; the pertinent innovation is the selection of propylene carbonate (PC) as a solvent having significantly more stability, relative to other solvents that have been tried. The discussion also addresses the need for an electrolyte additive, denoted an anion receptor, to complex the fluoride ion; the pertinent innovation is the selection of tris(hexafluoroisopropyl) borate as a superior alternative to the prior anion receptor, which was tris(pentafluorophenyl) borate.

  12. Microscopic physical and chemical properties of graphite intercalation compounds

    SciTech Connect

    Eklund, P.C.

    1992-08-24

    Optical spectroscopy (Raman, FTIR and Reflection ) was used to study a variety of acceptor- and donor-type compounds synthesized to determine the microscopic models consistent with the spectrocsopic results. General finding is that the electrical conduction properties of these compounds can be understood on the basis that the intercalation of atomic and/or molecular species between the host graphite layers either raises or lowers the Fermi level (E{sub F)} in a graphitic band structure. This movement of E{sub F} is accomplished via a charge transfer of electrons from the intercalate layers to the graphitic layers (donor compounds), or vice versa (acceptor compounds). Furthermore, the band structure must be modified to take into account the layers of charge that occur as a result of the charge transfer. This charge layering introduces additional bands of states near E{sub F}, which are discussed. Charge-transfer also induces a perturbation of the graphitic normal mode frequencies which can be understood as the result of a contraction (acceptor compounds) or expansion (donor compounds) of the intralayer C-C bonds. Ab-initio calculations support this view and are in reasonable agreement with experimental data.

  13. An intercalation-locked parallel-stranded DNA tetraplex

    DOE PAGESBeta

    Tripathi, S.; Zhang, D.; Paukstelis, P. J.

    2015-01-27

    DNA has proved to be an excellent material for nanoscale construction because complementary DNA duplexes are programmable and structurally predictable. However, in the absence of Watson–Crick pairings, DNA can be structurally more diverse. Here, we describe the crystal structures of d(ACTCGGATGAT) and the brominated derivative, d(ACBrUCGGABrUGAT). These oligonucleotides form parallel-stranded duplexes with a crystallographically equivalent strand, resulting in the first examples of DNA crystal structures that contains four different symmetric homo base pairs. Two of the parallel-stranded duplexes are coaxially stacked in opposite directions and locked together to form a tetraplex through intercalation of the 5'-most A–A base pairs betweenmore » adjacent G–G pairs in the partner duplex. The intercalation region is a new type of DNA tertiary structural motif with similarities to the i-motif. 1H–1H nuclear magnetic resonance and native gel electrophoresis confirmed the formation of a parallel-stranded duplex in solution. Finally, we modified specific nucleotide positions and added d(GAY) motifs to oligonucleotides and were readily able to obtain similar crystals. This suggests that this parallel-stranded DNA structure may be useful in the rational design of DNA crystals and nanostructures.« less

  14. An intercalation-locked parallel-stranded DNA tetraplex

    SciTech Connect

    Tripathi, S.; Zhang, D.; Paukstelis, P. J.

    2015-01-27

    DNA has proved to be an excellent material for nanoscale construction because complementary DNA duplexes are programmable and structurally predictable. However, in the absence of Watson–Crick pairings, DNA can be structurally more diverse. Here, we describe the crystal structures of d(ACTCGGATGAT) and the brominated derivative, d(ACBrUCGGABrUGAT). These oligonucleotides form parallel-stranded duplexes with a crystallographically equivalent strand, resulting in the first examples of DNA crystal structures that contains four different symmetric homo base pairs. Two of the parallel-stranded duplexes are coaxially stacked in opposite directions and locked together to form a tetraplex through intercalation of the 5'-most A–A base pairs between adjacent G–G pairs in the partner duplex. The intercalation region is a new type of DNA tertiary structural motif with similarities to the i-motif. 1H–1H nuclear magnetic resonance and native gel electrophoresis confirmed the formation of a parallel-stranded duplex in solution. Finally, we modified specific nucleotide positions and added d(GAY) motifs to oligonucleotides and were readily able to obtain similar crystals. This suggests that this parallel-stranded DNA structure may be useful in the rational design of DNA crystals and nanostructures.

  15. Duplex-Selective Ruthenium-based DNA Intercalators

    PubMed Central

    Shade, Chad M.; Kennedy, Robert D.; Rouge, Jessica L.; Rosen, Mari S.; Wang, Mary X.; Seo, Soyoung E.; Clingerman, Daniel J.

    2016-01-01

    We report the design and synthesis of small molecules that exhibit enhanced luminescence in the presence of duplex rather than single-stranded DNA. The local environment presented by a well-known [Ru(dipyrido[2,3-a:3',2'-c]phenazine)L2]2+-based DNA intercalator was modified by functionalizing the bipyridine ligands with esters and carboxylic acids. By systematically varying the number and charge of the pendant groups, it was determined that decreasing the electrostatic interaction between the intercalator and the anionic DNA backbone reduced single-strand interactions and translated to better duplex specificity. In studying this class of complexes, a single RuII complex emerged that selectively luminesces in the presence of duplex DNA with little to no background from interacting with single stranded DNA. This complex shows promise as a new dye capable of selectively staining double versus single-stranded DNA in gel electrophoresis, which cannot be done with conventional SYBR dyes. PMID:26119581

  16. Controlled Sequestration of DNA Intercalated Drug by Polymer-Surfactant Supramolecular Assemblies.

    PubMed

    Mora, Aruna K; Singh, Prabhat K; Nath, Sukhendu

    2016-05-01

    Triblock copolymer and surfactant based supramolecular assemblies have been used for the controlled sequestration of the DNA intercalator. The triblock copolymer micelles do not affect the molecules that are intercalated in the DNA. However, on addition of charged surfactant to the triblock copolymer micellar solution, sequestration of the intercalated molecules from DNA to the polymer-surfactant supramolecular assemblies takes place. Such sequestration of the intercalated molecules in the polymer-surfactant supramolecular assemblies has been explained on the basis of the charged surface formed in the polymer micelles due to the addition of surfactants. Sequestration of the intercalated molecules from the DNA to the polymer-surfactant supramolecular assemblies has been monitored through the ground state absorption, steady state, and time-resolved emission measurements. It is shown that the extent of sequestration of the intercalated molecules can be finely tuned by tuning the concentration of the surfactant in the triblock copolymer solution. Quantitative sequestration of the intercalated molecules by the supramolecular assemblies has been achieved. Such controlled sequestration of the DNA intercalated molecules by polymer-surfactant supramolecular assemblies can be used to study the binding of drug with DNA and may be useful in applications like detoxification in the case of drug overdose. PMID:27077791

  17. Adsorption and intercalation of Cs atoms on epitaxial graphene on Ir(111)

    NASA Astrophysics Data System (ADS)

    Lazic, Predrag; Petrovic, Marin; Srut, Iva; Pletikosic, Ivo; Milun, Milorad; Pervan, Petar; Runte, Sven; Busse, Carsten; Michely, Thomas; Sokcevic, Damir; Brako, Radovan; Atodiresei, Nicolae; Sadowski, Jurek; Pan, Zhi-Hu; Valla, Tonica; Kralj, Marko

    2013-03-01

    From the experimental studies of surface adsorption of Cs atoms and their intercalation under epitaxial graphene on Ir(111) it is known that both - adsorbed and intercalated phase of Cs atoms coexist. However, adsorbed phase is realized as a diluted superlattice adlayer of Cs atom while intercalated phase is a dense Cs layer. The preference for intercalated phase at large Cs layer densities can not be obtained from the DFT calculations with semilocal (GGA) functionals. Only after the van der Waals interaction is taken into account the agreement with experiment is achieved. From the results of calculations it follows that the main energy contribution responsible for the switching of preference from adsorption to intercalation is the graphene delamination energy from the Ir(111) surface which is dominantly of the van der Waals nature.

  18. Dual Element Intercalation into 2D Layered Bi₂Se₃ Nanoribbons.

    PubMed

    Chen, Karen P; Chung, Frank R; Wang, Mengjing; Koski, Kristie J

    2015-04-29

    We demonstrate the intercalation of multiple zero-valent atomic species into two-dimensional (2D) layered Bi2Se3 nanoribbons. Intercalation is performed chemically through a stepwise combination of disproportionation redox reactions, hydrazine reduction, or carbonyl decomposition. Traditional intercalation is electrochemical thus limiting intercalant guests to a single atomic species. We show that multiple zero-valent atoms can be intercalated through this chemical route into the host lattice of a 2D crystal. Intermetallic species exhibit unique structural ordering demonstrated in a variety of superlattice diffraction patterns. We believe this method is general and can be used to achieve a wide variety of new 2D materials previously inaccessible. PMID:25851420

  19. Melamine/Stearic Acid Composite Nanowires and Vesicles with an Intercalated Nanostructure Prepared through NCCM Method

    NASA Astrophysics Data System (ADS)

    Guo, Juan; Chen, Dao-yong

    2012-12-01

    A solvent-non-solvent method invented in our laboratory for preparing non-covalently connected micelles (NCCM) was used to intercalate melamine (MA) molecules into stearic acid (SA) bilayers to form the composite nanoparticles with an intercalated nanostructure in which a melamine bilayer is sandwiched between two stearic acid bilayers, NCCM method helps to sufficiently mix the two components in nanospace and meanwhile inhibits the strong tendency of self-crystallization of MA, leading to the intercalation. Although the nanoparticles have a regular inner structure, the primary MA/SA nanoparticles have an irregular morphology. Regular nanoparticles were obtained through annealing the suspension of the primary nanoparticles. Through annealing at different temperatures, the MA/SA composite nanowires and vesicles with an intercalated structure were prepared respectively. It is proposed that the morphological change results from the change in the intercalated structure.

  20. Transient analysis of intercalation electrodes for parameter estimation

    NASA Astrophysics Data System (ADS)

    Devan, Sheba

    An essential part of integrating batteries as power sources in any application, be it a large scale automotive application or a small scale portable application, is an efficient Battery Management System (BMS). The combination of a battery with the microprocessor based BMS (called "smart battery") helps prolong the life of the battery by operating in the optimal regime and provides accurate information regarding the battery to the end user. The main purposes of BMS are cell protection, monitoring and control, and communication between different components. These purposes are fulfilled by tracking the change in the parameters of the intercalation electrodes in the batteries. Consequently, the functions of the BMS should be prompt, which requires the methodology of extracting the parameters to be efficient in time. The traditional transient techniques applied so far may not be suitable due to reasons such as the inability to apply these techniques when the battery is under operation, long experimental time, etc. The primary aim of this research work is to design a fast, accurate and reliable technique that can be used to extract parameter values of the intercalation electrodes. A methodology based on analysis of the short time response to a sinusoidal input perturbation, in the time domain is demonstrated using a porous electrode model for an intercalation electrode. It is shown that the parameters associated with the interfacial processes occurring in the electrode can be determined rapidly, within a few milliseconds, by measuring the response in the transient region. The short time analysis in the time domain is then extended to a single particle model that involves bulk diffusion in the solid phase in addition to interfacial processes. A systematic procedure for sequential parameter estimation using sensitivity analysis is described. Further, the short time response and the input perturbation are transformed into the frequency domain using Fast Fourier Transform

  1. Copper-Intercalated Birnessite as a Water Oxidation Catalyst.

    PubMed

    Thenuwara, Akila C; Shumlas, Samantha L; Attanayake, Nuwan H; Cerkez, Elizabeth B; McKendry, Ian G; Frazer, Laszlo; Borguet, Eric; Kang, Qing; Zdilla, Michael J; Sun, Jianwei; Strongin, Daniel R

    2015-11-24

    We report a synthetic method to increase the catalytic activity of birnessite toward water oxidation by intercalating copper in the interlayer region of the layered manganese oxide. Intercalation of copper, verified by XRD, XPS, ICP, and Raman spectroscopy, was accomplished by exposing a suspension of birnessite to a Cu(+)-bearing precursor molecule that underwent disproportionation in solution to yield Cu(0) and Cu(2+). Electrocatalytic studies showed that the Cu-modified birnessite exhibited an overpotential for water oxidation of ∼490 mV (at 10 mA/cm(2)) and a Tafel slope of 126 mV/decade compared to ∼700 mV (at 10 mA/cm(2)) and 240 mV/decade, respectively, for birnessite without copper. Impedance spectroscopy results suggested that the charge transfer resistivity of the Cu-modified sample was significantly lower than Cu-free birnessite, suggesting that Cu in the interlayer increased the conductivity of birnessite leading to an enhancement of water oxidation kinetics. Density functional theory calculations show that the intercalation of Cu(0) into a layered MnO2 model structure led to a change of the electronic properties of the material from a semiconductor to a metallic-like structure. This conclusion from computation is in general agreement with the aforementioned impedance spectroscopy results. X-ray photoelectron spectroscopy (XPS) showed that Cu(0) coexisted with Cu(2+) in the prepared Cu-modified birnessite. Control experiments using birnessite that was decorated with only Cu(2+) showed a reduction in water oxidation kinetics, further emphasizing the importance of Cu(0) for the increased activity of birnessite. The introduction of Cu(0) into the birnessite structure also increased the stability of the electrocatalyst. At a working current of 2 mA, the Cu-modified birnessite took ∼3 times longer for the overpotential for water oxdiation to increase by 100 mV compared to when Cu was not present in the birnessite. PMID:26477450

  2. STS-92 Discovery Launch

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Viewed from across the waters of Banana Creek, clouds of smoke and steam are illuminated by the flames from Space Shuttle Discovery'''s perfect on-time launch at 7:17 p.m. EDT. Discovery carries a crew of seven on a construction flight to the International Space Station. Discovery also carries a payload that includes the Integrated Truss Structure Z-1, first of 10 trusses that will form the backbone of the Space Station, and the third Pressurized Mating Adapter that will provide a Shuttle docking port for solar array installation on the sixth Station flight and Lab installation on the seventh Station flight. Discovery'''s landing is expected Oct. 22 at 2:10 p.m. EDT.

  3. Computational drug discovery

    PubMed Central

    Ou-Yang, Si-sheng; Lu, Jun-yan; Kong, Xiang-qian; Liang, Zhong-jie; Luo, Cheng; Jiang, Hualiang

    2012-01-01

    Computational drug discovery is an effective strategy for accelerating and economizing drug discovery and development process. Because of the dramatic increase in the availability of biological macromolecule and small molecule information, the applicability of computational drug discovery has been extended and broadly applied to nearly every stage in the drug discovery and development workflow, including target identification and validation, lead discovery and optimization and preclinical tests. Over the past decades, computational drug discovery methods such as molecular docking, pharmacophore modeling and mapping, de novo design, molecular similarity calculation and sequence-based virtual screening have been greatly improved. In this review, we present an overview of these important computational methods, platforms and successful applications in this field. PMID:22922346

  4. Morphology and Structure of Amino-fatty Acid Intercalated Montmorillonite

    NASA Astrophysics Data System (ADS)

    Reyes, Larry; Sumera, Florentino

    2015-04-01

    Natural clays and its modified forms have been studied for their wide range of applications, including polymer-layered silicate, catalysts and adsorbents. For nanocomposite production, montmorillonite (MMT) clays are often modified with organic surfactants to favor its intermixing with the polymer matrix. In the present study, Na+-montmorillonite (Na+-MMT) was subjected to organo-modification with a protonated 12-aminolauric acid (12-ALA). The amount of amino fatty acid surfactants loaded was 25, 50, 100 and 200% the cation exchange capacity (CEC) of Na+-MMT (25CEC-AMMT, 50CEC-AMMT, 100CEC-AMMT and 200CEC-AMMT). Fatty acid-derived surfactants are an attractive resource of intercalating agents for clays due to their renewability and abundance. X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) were performed to determine the occurrence of intercalation of 12-ALA and their molecular structure in the clay's silicates. XRD analysis revealed that the interlayer spacing between the alumino-silicate layers increased from 1.25 nm to 1.82 nm with increasing ALA content. The amino fatty acid chains were considered to be in a flat monolayer structure at low surfactant loading, and a bilayered to a pseudotrilayered structure at high surfactant loading. On the other hand, FTIR revealed that the alkyl chains adopt a gauche conformation, indicating their disordered state based on their CH2symmetric and asymmetric vibrations. Thermogravimetric analyses (TGA) allows the determination of the moisture and organic content in clays. Here, TGA revealed that the surfactant in the clay was thermally stable, with Td ranging from 353° C to 417° C. The difference in the melting behavior of the pristine amino fatty acids and confined fatty acids in the interlayer galleries of the clay were evaluated by Differential Scanning Calorimerty (DSC). The melting temperatures (Tm) of the amino fatty acid in the clay were initially found to be higher than those of the free

  5. Dielectric properties of halloysite and halloysite-formamide intercalate

    SciTech Connect

    Adamczyk, M. Rok, M.; Wolny, A.; Orzechowski, K.

    2014-01-14

    Due to a high increase in electromagnetic pollution, the protection from non-ionizing electromagnetic radiation (EMR) represents an important problem of contemporary environmental science. We are searching for natural materials with the potential for EMR screening. We have discovered that hydro-halloysite has interesting properties as an EMR absorber. Unfortunately, it is a very unstable material. Drying it for even a short period of time leads to the loss of desired properties. In the paper, we have demonstrated that the intercalation of halloysite (the process of introducing guest molecules into the mineral structure) makes it possible to recover the ability to absorb an electromagnetic wave and obtain a promising material for electromagnetic field shielding applications.

  6. Water Intercalation for Seamless, Electrically Insulating, and Thermally Transparent Interfaces.

    PubMed

    Wang, Yanlei; Xu, Zhiping

    2016-01-27

    The interface between functional nanostructures and host substrates is of pivotal importance in the design of their nanoelectronic applications because it conveys energy and information between the device and environment. We report here an interface-engineering approach to establish a seamless, electrically insulating, while thermally transparent interface between graphene and metal substrates by introducing water intercalation. Molecular dynamics simulations and first-principles calculations are performed to demonstrate this concept of design, showing that the presence of the interfacial water layer helps to unfold wrinkles formed in the graphene membrane, insulate the electronic coupling between graphene and the substrate, and elevate the interfacial thermal conductance. The findings here lay the ground for a new class of nanoelectronic setups through interface engineering, which could lead to significant improvement in the performance of nanodevices, such as the field-effect transistors. PMID:26720217

  7. Dielectric properties of halloysite and halloysite-formamide intercalate

    NASA Astrophysics Data System (ADS)

    Adamczyk, M.; Rok, M.; Wolny, A.; Orzechowski, K.

    2014-01-01

    Due to a high increase in electromagnetic pollution, the protection from non-ionizing electromagnetic radiation (EMR) represents an important problem of contemporary environmental science. We are searching for natural materials with the potential for EMR screening. We have discovered that hydro-halloysite has interesting properties as an EMR absorber. Unfortunately, it is a very unstable material. Drying it for even a short period of time leads to the loss of desired properties. In the paper, we have demonstrated that the intercalation of halloysite (the process of introducing guest molecules into the mineral structure) makes it possible to recover the ability to absorb an electromagnetic wave and obtain a promising material for electromagnetic field shielding applications.

  8. Intercalation of graphene on iridium with samarium atoms

    NASA Astrophysics Data System (ADS)

    Afanas'eva, E. Yu.; Rut'kov, E. V.; Gall, N. R.

    2016-07-01

    Intercalation of graphene on Ir (111) with Sm atoms is studied by methods of thermal desorption spectroscopy and thermionic emission. It is shown that adsorption of samarium at T = 300 K on graphene to concentrations of N ≤ 6 × 1014 atoms cm-2 followed by heating of the substrate leads to practically complete escape of adsorbate underneath the graphene layer. At N > 6 × 1014 atoms cm-2 and increasing temperature, a fraction of adsorbate remains on graphene in the form of two-dimensional "gas" and samarium islands and are desorbed in the range of temperatures of 1000-1200 K. Samarium remaining under the graphene is desorbed from the surface in the temperature range 1200-2150 K. Model conceptions for the samarium-graphene-iridium system in a wide temperature range are developed.

  9. An enhanced hydrogen adsorption enthalpy for fluoride intercalated graphite compounds.

    PubMed

    Cheng, Hansong; Sha, Xianwei; Chen, Liang; Cooper, Alan C; Foo, Maw-Lin; Lau, Garret C; Bailey, Wade H; Pez, Guido P

    2009-12-16

    We present a combined theoretical and experimental study on H(2) physisorption in partially fluorinated graphite. This material, first predicted computationally using ab initio molecular dynamics simulation and subsequently synthesized and characterized experimentally, represents a novel class of "acceptor type" graphite intercalated compounds that exhibit significantly higher isosteric heat of adsorption for H(2) at near ambient temperatures than previously demonstrated for commonly available porous carbon-based materials. The unusually strong interaction arises from the semi-ionic nature of the C-F bonds. Although a high H(2) storage capacity (>4 wt %) at room temperature is predicted not to be feasible due to the low heat of adsorption, enhanced storage properties can be envisaged by doping the graphitic host with appropriate species to promote higher levels of charge transfer from graphene to F(-) anions. PMID:19928879

  10. Many electron correlations in stage-1 graphene intercalation compounds

    SciTech Connect

    Acharya, Sidharth Sharma, Raman

    2015-05-15

    Many electron correlations in stage-1 graphene intercalation compounds (GICs) are studied in generalized-random-phase-approximation. With this approximation, we are able to study short range exchange and correlation effects in GICs. These exchange correlations leads to BCS superconducting states in which one electron correlates with another via its correlation hole to form a stable pair of electrons known as Cooper pair. Cooper pair energies are calculated as the excitations in S(q,ω) following a method similar to exciton energy calculations. Short range effects governing local field correction G(q,ω) are studied for all wave vectors and frequencies. We have found a reasonable agreement between our results and the earlier theoretical results.

  11. Gas insulated transmission line having low inductance intercalated sheath

    DOEpatents

    Cookson, Alan H.

    1978-01-01

    A gas insulated transmission line including an outer sheath, an inner conductor disposed within the outer sheath, and an insulating gas between the inner conductor and the outer sheath. The outer sheath comprises an insulating tube having first and second ends, and having interior and exterior surfaces. A first electrically conducting foil is secured to the interior surface of the insulating tube, is spirally wound from one tube end to the second tube end, and has a plurality of overlapping turns. A second electrically conducting foil is secured to the exterior surface of the insulating tube, and is spirally wound in the opposite direction from the first electrically conducting foil. By winding the foils in opposite directions, the inductances within the intercalated sheath will cancel each other out.

  12. Dry synthesis of lithium intercalated graphite powders and carbon fibers

    SciTech Connect

    Sacci, Robert L; Adamczyk, Leslie A; Veith, Gabriel M; Dudney, Nancy J

    2014-01-01

    Herein we describe the direct synthesis of lithium intercalated graphite by heating under vacuum or ball milling under pressurized Ar(g). Both methods allow for stoichometric control of Li-C ratio in batter-grade graphites and carbon fibers prior formation of a solid electrolyte interphase. The products' surface chemistries, as probed by XPS, suggest that LiC6 are extremely reactive with trace amounts of moisture or oxygen. The open circuit potential and SEM data show that the reactivity of the lithiated battery-grade graphite and the carbon fiber can be related to the density of edge/defect sites on the surfaces. Preliminary results of spontaneous SEI formation on Li-graphite in electrolyte are also given.

  13. Advantages of GPU technology in DFT calculations of intercalated graphene

    NASA Astrophysics Data System (ADS)

    Pešić, J.; Gajić, R.

    2014-09-01

    Over the past few years, the expansion of general-purpose graphic-processing unit (GPGPU) technology has had a great impact on computational science. GPGPU is the utilization of a graphics-processing unit (GPU) to perform calculations in applications usually handled by the central processing unit (CPU). Use of GPGPUs as a way to increase computational power in the material sciences has significantly decreased computational costs in already highly demanding calculations. A level of the acceleration and parallelization depends on the problem itself. Some problems can benefit from GPU acceleration and parallelization, such as the finite-difference time-domain algorithm (FTDT) and density-functional theory (DFT), while others cannot take advantage of these modern technologies. A number of GPU-supported applications had emerged in the past several years (www.nvidia.com/object/gpu-applications.html). Quantum Espresso (QE) is reported as an integrated suite of open source computer codes for electronic-structure calculations and materials modeling at the nano-scale. It is based on DFT, the use of a plane-waves basis and a pseudopotential approach. Since the QE 5.0 version, it has been implemented as a plug-in component for standard QE packages that allows exploiting the capabilities of Nvidia GPU graphic cards (www.qe-forge.org/gf/proj). In this study, we have examined the impact of the usage of GPU acceleration and parallelization on the numerical performance of DFT calculations. Graphene has been attracting attention worldwide and has already shown some remarkable properties. We have studied an intercalated graphene, using the QE package PHonon, which employs GPU. The term ‘intercalation’ refers to a process whereby foreign adatoms are inserted onto a graphene lattice. In addition, by intercalating different atoms between graphene layers, it is possible to tune their physical properties. Our experiments have shown there are benefits from using GPUs, and we reached an

  14. Single-molecule kinetics and footprinting of DNA bis-intercalation: the paradigmatic case of Thiocoraline

    PubMed Central

    Camunas-Soler, Joan; Manosas, Maria; Frutos, Silvia; Tulla-Puche, Judit; Albericio, Fernando; Ritort, Felix

    2015-01-01

    DNA bis-intercalators are widely used in molecular biology with applications ranging from DNA imaging to anticancer pharmacology. Two fundamental aspects of these ligands are the lifetime of the bis-intercalated complexes and their sequence selectivity. Here, we perform single-molecule optical tweezers experiments with the peptide Thiocoraline showing, for the first time, that bis-intercalation is driven by a very slow off-rate that steeply decreases with applied force. This feature reveals the existence of a long-lived (minutes) mono-intercalated intermediate that contributes to the extremely long lifetime of the complex (hours). We further exploit this particularly slow kinetics to determine the thermodynamics of binding and persistence length of bis-intercalated DNA for a given fraction of bound ligand, a measurement inaccessible in previous studies of faster intercalating agents. We also develop a novel single-molecule footprinting technique based on DNA unzipping and determine the preferred binding sites of Thiocoraline with one base-pair resolution. This fast and radiolabelling-free footprinting technique provides direct access to the binding sites of small ligands to nucleic acids without the need of cleavage agents. Overall, our results provide new insights into the binding pathway of bis-intercalators and the reported selectivity might be of relevance for this and other anticancer drugs interfering with DNA replication and transcription in carcinogenic cell lines. PMID:25690887

  15. Thermodynamic Complexing of Monocyclopentadienylferrum (II) Intercalates with Double-Walled Carbon Nanotubes.

    PubMed

    Мykhailenko, О V; Prylutskyy, Yu I; Кomarov, І V; Strungar, А V

    2016-12-01

    By employing the methods of molecular mechanics, semi-empirical quantum-chemical РМ3 and Monte-Carlo, the positioning of monocyclopentadienylferrum (II) molecules in double-walled (5,5)@(10,10) carbon nanotubes (CNT) depending on their concentration and temperature has been studied. The molecules have been found out to form stable bonds with CNT walls, with a tendency between intercalate stability and the CNT structure. The temperature growth (over ~500 K) causes gradual bond ruining followed by extrusion of interwall intercalate. Further temperature increase up to 600-700 K is characterised with intercalate external surface desorption, stabilising the whole system and keeping the interwall intercalate only. The CNT's UV-spectrum (5,5)@(10,10) depending on the intercalate concentration and association constant of the "double-walled CNT-intercalate" system have been calculated. A combination of unique optical, electrical and magnetic behaviour of cyclopentadienyl complexes with their ability to form high-stable intercalate with CNT opens a prospect of their applying in nanotechnology. PMID:26951128

  16. A new way to synthesize superconducting metal-intercalated C60 and FeSe

    PubMed Central

    Takahei, Yuuki; Tomita, Keitaro; Itoh, Yugo; Ashida, Keishi; Lee, Ji-Hyun; Nishimoto, Naoki; Kimura, Takumi; Kudo, Kazutaka; Nohara, Minoru; Kubozono, Yoshihiro; Kambe, Takashi

    2016-01-01

    Doping with the optimum concentration of carriers (electrons or holes) can modify the physical properties of materials. Therefore, improved ways to achieve carrier doping have been pursued extensively for more than 50 years. Metal-intercalation is one of the most important techniques for electron doping of organic / inorganic solids, and has produced superconductors from insulators and metallic solids. The most successful examples are metal-intercalated graphite and C60 superconductors. Metal intercalation has been performed using solid-reaction and liquid solvent techniques. However, precise control of the quantity of intercalants in the target solids can be difficult to achieve using these methods, as that quantity depends largely on the initial conditions. Here we report an electrochemical method for metal-intercalation, and demonstrate the preparation of superconductors using organic and inorganic materials (C60 and FeSe). The metal atoms are effectively intercalated into the spaces in C60 and FeSe solids by supplying an electric current between electrodes in a solvent that includes electrolytes. The recorded superconducting transition temperatures, Tc’s, were the same as those of metal-intercalated C60 and FeSe prepared using solid-reaction or liquid solvent techniques. This technique may open a new avenue in the search for organic / inorganic superconductors. PMID:26732250

  17. Strong DNA deformation required for extremely slow DNA threading intercalation by a binuclear ruthenium complex.

    PubMed

    Almaqwashi, Ali A; Paramanathan, Thayaparan; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C

    2014-10-01

    DNA intercalation by threading is expected to yield high affinity and slow dissociation, properties desirable for DNA-targeted therapeutics. To measure these properties, we utilize single molecule DNA stretching to quantify both the binding affinity and the force-dependent threading intercalation kinetics of the binuclear ruthenium complex Δ,Δ-[μ-bidppz-(phen)4Ru2]4+ (Δ,Δ-P). We measure the DNA elongation at a range of constant stretching forces using optical tweezers, allowing direct characterization of the intercalation kinetics as well as the amount intercalated at equilibrium. Higher forces exponentially facilitate the intercalative binding, leading to a profound decrease in the binding site size that results in one ligand intercalated at almost every DNA base stack. The zero force Δ,Δ-P intercalation Kd is 44 nM, 25-fold stronger than the analogous mono-nuclear ligand (Δ-P). The force-dependent kinetics analysis reveals a mechanism that requires DNA elongation of 0.33 nm for association, relaxation to an equilibrium elongation of 0.19 nm, and an additional elongation of 0.14 nm from the equilibrium state for dissociation. In cells, a molecule with binding properties similar to Δ,Δ-P may rapidly bind DNA destabilized by enzymes during replication or transcription, but upon enzyme dissociation it is predicted to remain intercalated for several hours, thereby interfering with essential biological processes. PMID:25245944

  18. A new way to synthesize superconducting metal-intercalated C60 and FeSe.

    PubMed

    Takahei, Yuuki; Tomita, Keitaro; Itoh, Yugo; Ashida, Keishi; Lee, Ji-Hyun; Nishimoto, Naoki; Kimura, Takumi; Kudo, Kazutaka; Nohara, Minoru; Kubozono, Yoshihiro; Kambe, Takashi

    2016-01-01

    Doping with the optimum concentration of carriers (electrons or holes) can modify the physical properties of materials. Therefore, improved ways to achieve carrier doping have been pursued extensively for more than 50 years. Metal-intercalation is one of the most important techniques for electron doping of organic / inorganic solids, and has produced superconductors from insulators and metallic solids. The most successful examples are metal-intercalated graphite and C60 superconductors. Metal intercalation has been performed using solid-reaction and liquid solvent techniques. However, precise control of the quantity of intercalants in the target solids can be difficult to achieve using these methods, as that quantity depends largely on the initial conditions. Here we report an electrochemical method for metal-intercalation, and demonstrate the preparation of superconductors using organic and inorganic materials (C60 and FeSe). The metal atoms are effectively intercalated into the spaces in C60 and FeSe solids by supplying an electric current between electrodes in a solvent that includes electrolytes. The recorded superconducting transition temperatures, Tc's, were the same as those of metal-intercalated C60 and FeSe prepared using solid-reaction or liquid solvent techniques. This technique may open a new avenue in the search for organic / inorganic superconductors. PMID:26732250

  19. A new way to synthesize superconducting metal-intercalated C60 and FeSe

    NASA Astrophysics Data System (ADS)

    Takahei, Yuuki; Tomita, Keitaro; Itoh, Yugo; Ashida, Keishi; Lee, Ji-Hyun; Nishimoto, Naoki; Kimura, Takumi; Kudo, Kazutaka; Nohara, Minoru; Kubozono, Yoshihiro; Kambe, Takashi

    2016-01-01

    Doping with the optimum concentration of carriers (electrons or holes) can modify the physical properties of materials. Therefore, improved ways to achieve carrier doping have been pursued extensively for more than 50 years. Metal-intercalation is one of the most important techniques for electron doping of organic / inorganic solids, and has produced superconductors from insulators and metallic solids. The most successful examples are metal-intercalated graphite and C60 superconductors. Metal intercalation has been performed using solid-reaction and liquid solvent techniques. However, precise control of the quantity of intercalants in the target solids can be difficult to achieve using these methods, as that quantity depends largely on the initial conditions. Here we report an electrochemical method for metal-intercalation, and demonstrate the preparation of superconductors using organic and inorganic materials (C60 and FeSe). The metal atoms are effectively intercalated into the spaces in C60 and FeSe solids by supplying an electric current between electrodes in a solvent that includes electrolytes. The recorded superconducting transition temperatures, Tc’s, were the same as those of metal-intercalated C60 and FeSe prepared using solid-reaction or liquid solvent techniques. This technique may open a new avenue in the search for organic / inorganic superconductors.

  20. Strong DNA deformation required for extremely slow DNA threading intercalation by a binuclear ruthenium complex

    PubMed Central

    Almaqwashi, Ali A.; Paramanathan, Thayaparan; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C.

    2014-01-01

    DNA intercalation by threading is expected to yield high affinity and slow dissociation, properties desirable for DNA-targeted therapeutics. To measure these properties, we utilize single molecule DNA stretching to quantify both the binding affinity and the force-dependent threading intercalation kinetics of the binuclear ruthenium complex Δ,Δ-[μ‐bidppz‐(phen)4Ru2]4+ (Δ,Δ-P). We measure the DNA elongation at a range of constant stretching forces using optical tweezers, allowing direct characterization of the intercalation kinetics as well as the amount intercalated at equilibrium. Higher forces exponentially facilitate the intercalative binding, leading to a profound decrease in the binding site size that results in one ligand intercalated at almost every DNA base stack. The zero force Δ,Δ-P intercalation Kd is 44 nM, 25-fold stronger than the analogous mono-nuclear ligand (Δ-P). The force-dependent kinetics analysis reveals a mechanism that requires DNA elongation of 0.33 nm for association, relaxation to an equilibrium elongation of 0.19 nm, and an additional elongation of 0.14 nm from the equilibrium state for dissociation. In cells, a molecule with binding properties similar to Δ,Δ-P may rapidly bind DNA destabilized by enzymes during replication or transcription, but upon enzyme dissociation it is predicted to remain intercalated for several hours, thereby interfering with essential biological processes. PMID:25245944

  1. Single-molecule kinetics and footprinting of DNA bis-intercalation: the paradigmatic case of Thiocoraline.

    PubMed

    Camunas-Soler, Joan; Manosas, Maria; Frutos, Silvia; Tulla-Puche, Judit; Albericio, Fernando; Ritort, Felix

    2015-03-11

    DNA bis-intercalators are widely used in molecular biology with applications ranging from DNA imaging to anticancer pharmacology. Two fundamental aspects of these ligands are the lifetime of the bis-intercalated complexes and their sequence selectivity. Here, we perform single-molecule optical tweezers experiments with the peptide Thiocoraline showing, for the first time, that bis-intercalation is driven by a very slow off-rate that steeply decreases with applied force. This feature reveals the existence of a long-lived (minutes) mono-intercalated intermediate that contributes to the extremely long lifetime of the complex (hours). We further exploit this particularly slow kinetics to determine the thermodynamics of binding and persistence length of bis-intercalated DNA for a given fraction of bound ligand, a measurement inaccessible in previous studies of faster intercalating agents. We also develop a novel single-molecule footprinting technique based on DNA unzipping and determine the preferred binding sites of Thiocoraline with one base-pair resolution. This fast and radiolabelling-free footprinting technique provides direct access to the binding sites of small ligands to nucleic acids without the need of cleavage agents. Overall, our results provide new insights into the binding pathway of bis-intercalators and the reported selectivity might be of relevance for this and other anticancer drugs interfering with DNA replication and transcription in carcinogenic cell lines. PMID:25690887

  2. Thermodynamic Complexing of Monocyclopentadienylferrum (II) Intercalates with Double-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Mykhailenko, O. V.; Prylutskyy, Yu I.; Komarov, I. V.; Strungar, A. V.

    2016-03-01

    By employing the methods of molecular mechanics, semi-empirical quantum-chemical PM3 and Monte-Carlo, the positioning of monocyclopentadienylferrum (II) molecules in double-walled (5,5)@(10,10) carbon nanotubes (CNT) depending on their concentration and temperature has been studied. The molecules have been found out to form stable bonds with CNT walls, with a tendency between intercalate stability and the CNT structure. The temperature growth (over ~500 K) causes gradual bond ruining followed by extrusion of interwall intercalate. Further temperature increase up to 600-700 K is characterised with intercalate external surface desorption, stabilising the whole system and keeping the interwall intercalate only. The CNT's UV-spectrum (5,5)@(10,10) depending on the intercalate concentration and association constant of the "double-walled CNT-intercalate" system have been calculated. A combination of unique optical, electrical and magnetic behaviour of cyclopentadienyl complexes with their ability to form high-stable intercalate with CNT opens a prospect of their applying in nanotechnology.

  3. Fabrication and Resistivity of IBr Intercalated Vapor-Grown Carbon Fiber Composites

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Smith, Jaclyn M.; Gahl, Gregory K.; Stevens, Eric C.; Gaier, Elizabeth M.

    1998-01-01

    Composites using vapor-crown carbon fibers (VGCF), the most conductive of the carbon fiber types, are attractive for applications where low density, high strength, and at least moderate conductivity are required, such as electromagnetic interference shielding covers for spacecraft. The conductivity can be enhanced another order of magnitude by intercalation of the VGCF. If a high Z intercalate is used, the protection of components from ionizing radiation can be enhanced also. Thus, the intercalation of VGCF with IBr is reported. Since composite testing is required to verify properties, the intercalation reaction optimization, stability of the intercalation compound, scale-up of the intercalation reaction, composite fabrication, and resistivity of the resulting composites is also reported. The optimum conditions for low resistivity and uniformity for the scaled up reaction (20-30 g of product) were 114 C for at least 72 hr, yielding a fiber with a resistivity of 8.7+/-2 micro-Omega-cm. The thermal stability of these fibers was poor, with degradation occurring at temperatures as low as 40 C in air, though they were insensitive to water vapor. Composite resistivity was 20-30 micro-Omega-cm, as measured by contactless conductivity measurements, about a factor of five higher than would be expected from a simple rule of mixtures. The addition of 1.0 percent Br2, intercalated microfibers increased the resistivity of the composites by more than 20 percent.

  4. Carbon dioxide intercalation in Na-fluorohectorite clay at near-ambient conditions

    NASA Astrophysics Data System (ADS)

    Fossum, Jon Otto; Hemmen, Henrik; Rolseth, Erlend G.; Fonseca, Davi; Lindbo Hansen, Elisabeth; Plivelic, Tomas

    2012-02-01

    A molecular dynamics study by Cygan et al.[1] shows the possibility of intercalation and retention of CO2 in smectite clays at 37 ^oC and 200 bar, which suggests that clay minerals may prove suitable for carbon capture and carbon dioxide sequestration. In this work we show from x-ray diffraction measurements that gaseous CO2 intercalates into the interlayer space of the synthetic smectite clay Na-fluorohectorite. The mean interlayer distance of the clay when CO2 is intercalated is 12.5 å at -20 C and 15 bar. The magnitude of the expansion of the interlayer upon intercalation is indistinguishable from that of the dehydrated-monohydrated intercalation of H2O, but this possibility is ruled out by careful repeating the measurements exposing the clay to nitrogen gas. The dynamics of the CO2 intercalation process displays a higher intercalation rate at increased pressure, and the rate is several orders of magnitude slower than that of water or vapor at ambient pressure and temperature.[4pt] [1] Cygan, R. T.; Romanov, V. N.; Myshakin, E. M. Natural materials for carbon capture; Techincal report SAND2010-7217; Sandia National Laboratories: Albuquerque, New Mexico, November, 2010.

  5. Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

    SciTech Connect

    Martins, Marcel G.; Martins, Daniel O.T.A.; Carvalho, Beatriz L.C. de; Mercante, Luiza A.; Soriano, Stéphane; Andruh, Marius; Vieira, Méri D.; Vaz, Maria G.F.

    2015-08-15

    In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide – CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad{sup +}) and two binuclear coordination compounds, [Ni(valpn)Ln]{sup 3+}, where H{sub 2}valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=Gd{sup III}; Dy{sup III}. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar space of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species. - Graphical abstract: Montmorillonite clay was employed as inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange - Highlights: • Montmorillonite was employed as a host material. • Three molecular magnetic compounds were intercalated through ion exchange. • The compounds were successful intercalated maintaining the layered structure. • The hybrid materials exhibited similar magnetic behavior as the pure magnetic guest.

  6. The intercalation of bicyclic and tricyclic carboxylates into layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Khan, Aamir I.; Williams, Gareth R.; Hu, Gang; Rees, Nicholas H.; O'Hare, Dermot

    2010-12-01

    Twenty-four nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised for the first time. Eight carboxylates were successfully intercalated into [LiAl 2(OH) 6]Cl· yH 2O, [Ca 2Al(OH) 6]NO 3· yH 2O, and [Mg 2Al(OH) 6]NO 3· yH 2O, and the products fully characterised. Guest species incorporated include 1-adamantane carboxylate (1- AC) and 5-norbornene-2- endo-3- exo-dicarboxylate. In some cases, carbonate anions were co-intercalated with the organic guest, and in others poorly crystalline aluminium hydroxides formed as by-products. Sharper resonances were observed in the 13C solid-state NMR spectra of the 1- AC intercalates than in the spectrum of pure 1- AC, suggesting increased order in the arrangement of the cyclic cages in the intercalates. Where possible, time-resolved in situ X-ray diffraction was employed to study the nanoscopic steps involved in the intercalation reactions. These investigations showed that the reactions are one-step processes, proceeding directly to the fully exchanged intercalate with no intermediate phases. The intercalation processes were found to be nucleation controlled.

  7. The effect of drug-DNA interactions on the intercalation site formation

    NASA Astrophysics Data System (ADS)

    Miroshnychenko, K. V.; Shestopalova, A. V.

    The problem of intercalation site formation in the undistorted B-DNA of different length and sequence was considered. Three models of DNA intercalation targets were proposed that accounted for the binding features of intercalators ethidium, daunomycin and 9-amino[N-(2-dimethylamino)ethyl]-acridine-4-carboxamide (9-amino-DACA). The automated docking of ligands into the constructed DNA-targets produced correct structures of complexes for ethidium and daunomycin when asymmetrically unwound DNA was used as target. To obtain the correct structure of 9-amino-DACA-DNA complex, the manual docking was applied. The results of docking of ligands into different DNA-targets indicate that, upon formation of the intercalation target, it is sufficient to take into account only the most significant unwinding in one particular helical step: in the intercalation step (for ethidium and 9-amino-DACA) or in the adjacent helical step (for daunomycin). The unwinding or overwinding of subsequent helical steps could be refined later during the optimization of the obtained intercalation complex. The unwinding of the DNA helical step on the large angle produces the 5‧-North/3‧-South asymmetry of sugar conformations in this step. The value of the total unwinding of the DNA in the intercalation complex was found to be dependent on the sequence and length of the DNA-target.

  8. Antibiotic drug discovery.

    PubMed

    Wohlleben, Wolfgang; Mast, Yvonne; Stegmann, Evi; Ziemert, Nadine

    2016-09-01

    Due to the threat posed by the increase of highly resistant pathogenic bacteria, there is an urgent need for new antibiotics; all the more so since in the last 20 years, the approval for new antibacterial agents had decreased. The field of natural product discovery has undergone a tremendous development over the past few years. This has been the consequence of several new and revolutionizing drug discovery and development techniques, which is initiating a 'New Age of Antibiotic Discovery'. In this review, we concentrate on the most significant discovery approaches during the last and present years and comment on the challenges facing the community in the coming years. PMID:27470984

  9. Discovery and Classification in Astronomy

    NASA Astrophysics Data System (ADS)

    Dick, Steven J.

    2013-10-01

    Preface; Abbreviations; Introduction: the natural history of the heavens and the natural history of discovery; Part I. Entrée: 1. The Pluto affair; Part II. Narratives of Discovery: 2. Moons, rings, and asteroids: discovery in the realm of the planets; 3. In Herschel's gardens: nebulous discoveries in the realm of the stars; 4. Dwarfs, giants, and planets (again!): the discovery of the stars themselves; 5. Galaxies, quasars, and clusters: discovery in the realm of the galaxies; Part III. Patterns of Discovery: 6. The structure of discovery; 7. The varieties of discovery; 8. Discovery and classification; Part IV. Drivers of Discovery: 9. Technology and theory as drivers of discovery; Part V. The Synthesis of Discovery: 10. Luxuriant gardens and the master narrative; 11. The meaning of discovery; Appendix I; Appendix II.

  10. Cerium Oxide Nanoclusters on Graphene/Ru(0001): Intercalation of Oxygen via Spillover.

    PubMed

    Novotny, Zbynek; Netzer, Falko P; Dohnálek, Zdenek

    2015-08-25

    Cerium oxide is an important catalytic material known for its ability to store and release oxygen, and as such, it has been used in a range of applications, both as an active catalyst and as a catalyst support. Using scanning tunneling microscopy and Auger electron spectroscopy, we investigated oxygen interactions with CeOx nanoclusters on a complete graphene monolayer-covered Ru(0001) surface at elevated temperatures (600-725 K). Under oxidizing conditions (PO2 = 1 × 10(-7) Torr), oxygen intercalation under the graphene layer is observed. Time dependent studies demonstrate that the intercalation proceeds via spillover of oxygen from CeOx nanoclusters through the graphene (Gr) layer onto the Ru(0001) substrate and extends until the Gr layer is completely intercalated. Atomically resolved images further show that oxygen forms a p(2 × 1) structure underneath the Gr monolayer. Temperature dependent studies yield an apparent kinetic barrier for the intercalation of 1.21 eV. This value correlates well with the theoretically determined value for the reduction of small CeO2 clusters reported previously. At higher temperatures, the intercalation is followed by a slower etching of the intercalated graphene (apparent barrier of 1.60 eV). Vacuum annealing of the intercalated Gr leads to the formation of carbon monoxide, causing etching of the graphene film, demonstrating that the spillover of oxygen is not reversible. In agreement with previous studies, no intercalation is observed on a complete graphene monolayer without CeOx clusters, even in the presence of a large number of point defects. These studies demonstrate that the easily reducible CeOx clusters act as intercalation gateways capable of efficiently delivering oxygen underneath the graphene layer. PMID:26230753

  11. Synthesis of reduced graphene oxide intercalated ZnO quantum dots nanoballs for selective biosensing detection

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Zhao, Minggang; Li, Yingchun; Fan, Sisi; Ding, Longjiang; Liang, Jingjing; Chen, Shougang

    2016-07-01

    ZnO quantum dots (QDs), reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) are always used in sensors due to their excellent electrochemical characteristics. In this work, ZnO QDs were intercalated by rGO sheets with cross-linked MWCNTs to construct intercalation nanoballs. A MWCNTs/rGO/ZnO QDs 3D hierarchical architecture was fabricated on supporting Ni foam, which exhibited excellent mechanical, kinetic and electrochemical properties. The intercalation construction can introduce strong interfacial effects to improve the surface electronic state. The selectively determinate of uric acid, dopamine, and ascorbic acid by an electrode material using distinct applied potentials was realized.

  12. High voltage and high specific capacity dual intercalating electrode Li-ion batteries

    NASA Technical Reports Server (NTRS)

    West, William C. (Inventor); Blanco, Mario (Inventor)

    2010-01-01

    The present invention provides high capacity and high voltage Li-ion batteries that have a carbonaceous cathode and a nonaqueous electrolyte solution comprising LiF salt and an anion receptor that binds the fluoride ion. The batteries can comprise dual intercalating electrode Li ion batteries. Methods of the present invention use a cathode and electrode pair, wherein each of the electrodes reversibly intercalate ions provided by a LiF salt to make a high voltage and high specific capacity dual intercalating electrode Li-ion battery. The present methods and systems provide high-capacity batteries particularly useful in powering devices where minimizing battery mass is important.

  13. Unique properties of α-NaFeO{sub 2}: De-intercalation of sodium via hydrolysis and the intercalation of guest molecules into the extract solution

    SciTech Connect

    Monyoncho, Evans; Bissessur, Rabin

    2013-07-15

    Graphical abstract: - Highlights: • Facile de-intercalating Na from NaFeO2. • Formation of layered sodium hydrogen carbonate hydrate. • Intercalation chemistry on layered sodium hydrogen carbonate hydrate. - Abstract: We report on a versatile method for the de-intercalation of Na from α-NaFeO{sub 2} by using water to produce α-Na{sub 1−x}FeO{sub 2}, where x ≈ 1. This de-intercalation technique provides an excellent route to ion exchange Na with other metal ions in α-NaFeO{sub 2}. The hydrolysis mechanism is provided. We show that the extracted solution captures CO{sub 2} from the atmosphere leading to the formation of sodium hydrogen carbonate hydrate crystals. The lamellar structure of the hydrate crystals was confirmed by powder X-ray diffraction, and were found Na-deficient via elemental analysis. Intercalation of guest molecules such as polymers, alcohols, and inorganic ions into the gallery space of the newly formed sodium hydrogen carbonate hydrate crystals was demonstrated by the use of powder X-ray diffraction technique. The reported materials were also characterized by Mössbauer spectroscopy, thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy.

  14. Decades of Discovery

    DOE R&D Accomplishments Database

    2011-06-01

    For the past two-and-a-half decades, the Office of Science at the U.S. Department of Energy has been at the forefront of scientific discovery. Over 100 important discoveries supported by the Office of Science are represented in this document.

  15. Drug discovery in academia.

    PubMed

    Verkman, A S

    2004-03-01

    Drug discovery and development is generally done in the commercial rather than the academic realm. Drug discovery involves target discovery and validation, lead identification by high-throughput screening, and lead optimization by medicinal chemistry. Follow-up preclinical evaluation includes analysis in animal models of compound efficacy and pharmacology (ADME: administration, distribution, metabolism, elimination) and studies of toxicology, specificity, and drug interactions. Notwithstanding the high-cost, labor-intensive, and non-hypothesis-driven aspects of drug discovery, the academic setting has a unique and expanding niche in this important area of investigation. For example, academic drug discovery can focus on targets of limited commercial value, such as third-world and rare diseases, and on the development of research reagents such as high-affinity inhibitors for pharmacological "gene knockout" in animal models ("chemical genetics"). This review describes the practical aspects of the preclinical drug discovery process for academic investigators. The discovery of small molecule inhibitors and activators of the cystic fibrosis transmembrane conductance regulator is presented as an example of an academic drug discovery program that has yielded new compounds for physiology research and clinical development. PMID:14761879

  16. Serendipity and Scientific Discovery.

    ERIC Educational Resources Information Center

    Rosenman, Martin F.

    1988-01-01

    The discovery of penicillin is cited in a discussion of the role of serendipity as it relates to scientific discovery. The importance of sagacity as a personality trait is noted. Successful researchers have questioning minds, are willing to view data from several perspectives, and recognize and appreciate the unexpected. (JW)

  17. Friends' Discovery Camp

    ERIC Educational Resources Information Center

    Seymour, Seth

    2008-01-01

    This article features Friends' Discovery Camp, a program that allows children with and without autism spectrum disorder to learn and play together. In Friends' Discovery Camp, campers take part in sensory-rich experiences, ranging from hands-on activities and performing arts to science experiments and stories teaching social skills. Now in its 7th…

  18. "Eureka, Eureka!" Discoveries in Science

    ERIC Educational Resources Information Center

    Agarwal, Pankaj

    2011-01-01

    Accidental discoveries have been of significant value in the progress of science. Although accidental discoveries are more common in pharmacology and chemistry, other branches of science have also benefited from such discoveries. While most discoveries are the result of persistent research, famous accidental discoveries provide a fascinating…

  19. Gd(III) complexes intercalated into hydroxy double salts as potential MRI contrast agents.

    PubMed

    Jin, Miao; Spillane, Dominic E M; Geraldes, Carlos F G C; Williams, Gareth R; Bligh, S W Annie

    2015-12-21

    The ion exchange intercalation of two Gd-based magnetic resonance imaging contrast agents into hydroxy double salts (HDSs) is reported. The presence of Gd(3+) diethylenetriaminepentaacetate and Gd(3+) diethylenetriaminepenta(methylenephosphonate) complexes in the HDS lattice after intercalation was confirmed by microwave plasma-atomic emission spectroscopy. The structural aspects of the HDS-Gd composites were studied by X-ray diffraction, with the intercalates having an interlayer spacing of 14.5-18.6 Å. Infrared spectroscopy confirmed the presence of characteristic vibration peaks associated with the Gd(3+) complexes in the intercalation compounds. The proton relaxivities of the Gd(3+) complex-loaded composites were 2 to 5-fold higher in longitudinal relaxivity, and up to 10-fold higher in transverse relaxivity, compared to solutions of the pure complexes. These data demonstrate that the new composites reported here are potentially potent MRI contrast agents. PMID:26568157

  20. Synthesis of new oligothiophene derivatives and their intercalation compounds: Orientation effects

    USGS Publications Warehouse

    Ibrahim, M.A.; Lee, B.-G.; Park, N.-G.; Pugh, J.R.; Eberl, D.D.; Frank, A.J.

    1999-01-01

    The orientation dependence of intercalated oligothiophene derivatives in vermiculite and metal disulfides MS2 (M = Mo, Ti and Zr) on the pendant group on the thiophene ring and the host material was studied by X-ray diffraction (XRD) and solid state nuclear magnetic resonance spectroscopy. Amino and nitro derivatives of bi-, ter- and quarter-thiophenes were synthesized for the first time. The amino-oligothiophenes were intercalated into vermiculite by an exchange reaction with previously intercalated octadecylammonium vermiculite and into MS2 by the intercalation-exfoliation technique. Analysis of the XRD data indicates that a monolayer of amino-oligothiophene orients perpendicularly to the silicate surface in vermiculite and lies flat in the van der Waals gap of MS2.

  1. Periodic arrays of intercalated atoms in twisted bilayer graphene: An ab initio investigation

    NASA Astrophysics Data System (ADS)

    Miwa, R. H.; Venezuela, P.; Morell, Eric Suárez

    2015-09-01

    We have performed an ab initio investigation of transition metals (TMs =Mo ,Ru ,Co ,andPt ) embedded in twisted bilayer graphene (tBG) layers. Our total energy results reveal that, triggered by the misalignment between the graphene layers, Mo and Ru atoms may form a quasiperiodic (triangular) array of intercalated atoms. In contrast, the formation of those structures is not expected for the other TMs, the Co and Pt atoms. The net magnetic moment (m ) of Mo and Ru atoms may be quenched upon intercalation, depending on the stacking region (AA or AB). For instance, we find a magnetic moment of 0.3 μB(1.8 μB) for Ru atoms intercalated between the AA (AB) regions of the stacked twisted layers. Through simulated scanning tunneling microscopy (STM) images, we verify that the presence of intercalated TMs can be identified by the formation of bright (hexagonal) spots lying on the graphene surface.

  2. Optimization of the Thermoelectric Figure of Merit in Crystalline C60 with Intercalation Chemistry.

    PubMed

    Kim, Jeong Yun; Grossman, Jeffrey C

    2016-07-13

    Crystalline C60 is an appealing candidate material for thermoelectric (TE) applications due to its extremely low thermal conductivity and potentially high electrical conductivity with metal atom intercalation. We investigate the TE properties of crystalline C60 intercalated with alkali and alkaline earth metals using both classical and quantum mechanical calculations. For the electronic structure, our results show that variation of intercalated metal atoms has a large impact on energy dispersions, which leads to broad tunability of the power factor. For the thermal transport, we show that dopants introduce strong phonon scattering into crystalline C60, leading to considerably lower thermal conductivity. Taking both into account, our calculations suggest that appropriate choice of metal atom intercalation in crystalline C60 could yield figures of merit near 1 at room temperature. PMID:27322341

  3. A micrographic and gravimetric study of intercalation and deintercalation of graphite fibers

    NASA Technical Reports Server (NTRS)

    Hung, C. C.

    1985-01-01

    Intercalation and deintercalation of Union Carbide P-100 graphite fibers with liquid and vaporous bromine was studied gravimetrically and microscopically. The mass of the bromine intercalated fibers was found to be 17 to 20 percent greater than their pristine counterpart. This variation decreased to 17 to 18 percent after heating in air for 3 days at 200 C and to 14.5 to 18 percent after 6 days of 260 C heating. The fiber length did not change throughout the experiment. The fiber diameter increased during intercalation and decreased slightly upon deintercalation but was not affected by heating to 260 C for 3 days in air. Comparing the mass and volume data to those with highly oriented pyrolitic graphite or natural single crystal graphite suggested the possibility that the intercalated P-100 fibers could be mostly stage 4.

  4. Novel alkylimidazolium/vanadium pentoxide intercalation compounds with excellent adsorption performance for methylene blue

    NASA Astrophysics Data System (ADS)

    Kong, AiGuo; Ding, Yong Jie; Wang, Ping; Zhang, Heng Qiang; Yang, Fan; Shan, Yong Kui

    2011-02-01

    Novel alkylimidazolium-intercalated V 2O 5 compounds were synthesized by a redox reaction between iodide ion and V 2O 5. The X-ray photoelectron spectroscopy and the diffuse reflectance UV-vis spectrometry experiments reveal that the vanadium in the intercalated V 2O 5 products was partially reduced by an iodide ion and the resultant iodine can be removed in the final products. The transmission electron microscope observation and X-ray diffraction analysis testify that the prepared alkylimidazolium/V 2O 5 intercalation compounds have typical lamellar structure with different d100 interlayer spacing values and the special straw-like nanofiber morphology with the length of 0.5-10 μm. Systematic investigation indicates that new intercalation compounds possess the extraordinary adsorption performance for methylene blue in an aqueous solution.

  5. Fabrication of a single layer graphene by copper intercalation on a SiC(0001) surface

    SciTech Connect

    Yagyu, Kazuma; Tochihara, Hiroshi; Tomokage, Hajime; Suzuki, Takayuki; Tajiri, Takayuki; Kohno, Atsushi; Takahashi, Kazutoshi

    2014-02-03

    Cu atoms deposited on a zero layer graphene grown on a SiC(0001) substrate, intercalate between the zero layer graphene and the SiC substrate after the thermal annealing above 600 °C, forming a Cu-intercalated single layer graphene. On the Cu-intercalated single layer graphene, a graphene lattice with superstructure due to moiré pattern is observed by scanning tunneling microscopy, and specific linear dispersion at the K{sup ¯} point as well as a characteristic peak in a C{sub 1s} core level spectrum, which is originated from a free-standing graphene, is confirmed by photoemission spectroscopy. The Cu-intercalated single layer graphene is found to be n-doped.

  6. Reversible chemochromic MoO3 nanoribbons through zerovalent metal intercalation.

    PubMed

    Wang, Mengjing; Koski, Kristie J

    2015-03-24

    Molybdenum trioxide (α-MoO3) is a 2D layered oxide with use in electrochromic and photochromic devices owing to its ability to reversibly change color between transparent and light blue with electrochemical or hydrogen intercalation. Despite its significant application potential, MoO3 performance is largely limited by the destructiveness of these intercalation techniques, insignificant coloration, and slow color response. We demonstrate a reversible chemochromic method, using intercalation of zerovalent metals into α-MoO3 nanoribbons (Sn, ∼2 at. %; Co, ∼4 at. %), to chemically alter MoO3 from transparent white to a deep blue indigo, resulting in enhanced coloration and chemically tunable optical properties. We present two strategies to reversibly tune the color response of MoO3 nanoribbons. Chromism can be reversed (i) by complete oxidative deintercalation with hydrogen peroxide or iodine or (ii) through a temperature-driven disorder-order phase transition of the intercalated zerovalent metal. PMID:25734624

  7. Strain-enhanced superconductivity of Mo X2(X =S or Se) bilayers with Na intercalation

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Jie; Gao, Bin; Dong, Shuai

    2016-04-01

    Mo X2(X =S or Se) is a semiconductor family with two-dimensional structure. And a recent calculation predicted the superconductivity in the electron-doped MoS2 monolayer. In this work, the electronic structure and lattice dynamics of Mo X2 bilayers with monolayer Na intercalated have been calculated. According to the electron-phonon interaction, it is predicted that these bilayers can be transformed from indirect-gap semiconductors to superconductors by Na intercalation. More interestingly, the biaxial tensile strain can significantly enhance the superconducting temperature up to ˜10 K in Na-intercalated MoS2. In addition, the phonon mean free path at room temperature is also greatly improved in Na-intercalated MoSe2, which is advantageous for related applications.

  8. Intercalating dyes for enhanced contrast in second-harmonic generation imaging of protein crystals.

    PubMed

    Newman, Justin A; Scarborough, Nicole M; Pogranichniy, Nicholas R; Shrestha, Rashmi K; Closser, Richard G; Das, Chittaranjan; Simpson, Garth J

    2015-07-01

    The second-harmonic generation (SHG) activity of protein crystals was found to be enhanced by up to ∼1000-fold by the intercalation of SHG phores within the crystal lattice. Unlike the intercalation of fluorophores, the SHG phores produced no significant background SHG from solvated dye or from dye intercalated into amorphous aggregates. The polarization-dependent SHG is consistent with the chromophores adopting the symmetry of the crystal lattice. In addition, the degree of enhancement for different symmetries of dyes is consistent with theoretical predictions based on the molecular nonlinear optical response. Kinetics studies indicate that intercalation arises over a timeframe of several minutes in lysozyme, with detectable enhancements within seconds. These results provide a potential means to increase the overall diversity of protein crystals and crystal sizes amenable to characterization by SHG microscopy. PMID:26143918

  9. Mapping the phase diagram of DNA force-induced melting in the presence of DNA intercalators

    NASA Astrophysics Data System (ADS)

    Vladescu, Ioana; McCauley, Micah; Nunez, Megan; Rouzina, Ioulia; Williams, Mark

    2006-03-01

    The interactions between single DNA molecules and different non-covalent binding agents - the classical intercalator ethidium and compounds from the family of ruthenium complexes - are investigated using an optical tweezers instrument and their effects on the structure and mechanical stability of DNA molecules are quantitatively analyzed using a model of force-induced melting. When a single DNA molecule is stretched beyond its normal contour length, a melting phase transition is observed. Drug binding increases the dsDNA contour length, decreases the DNA elongation upon melting, and increases the DNA melting force. At concentrations of intercalator above critical, no force induced melting of dsDNA is possible. The DNA stretching curves map out a phase diagram for DNA melting in the presence of intercalator, and define its critical point in the force-extension-drug concentration space. Our results allow for the complete thermodynamic characterization of the interaction of these intercalators with DNA.

  10. Preparation of titanate nanosheets and nanoribbons by exfoliation of amine intercalated titanates.

    PubMed

    Jeffery, A Anto; Pradeep, A; Rajamathi, Michael

    2016-05-14

    Amine intercalated titanates were synthesized by direct exchange of potassium ions of K2Ti4O9 by alkyl ammonium ions of various alkyl chain lengths. These intercalated solids exfoliate well in alcohols of different alkyl chain lengths and non-polar solvents such as toluene and hexane to yield colloidal dispersions of titanate nanosheets. The longer the alkyl chain of the intercalated amine the better the exfoliation of the intercalated titanate in long chain alcohols and non-polar solvents. While non-uniform rectangular nanosheets were obtained when aggressive sonication was employed for exfoliating the solids, nanoribbons were obtained when the exfoliation was carried out by gently stirring the solids in the solvent. PMID:27089839

  11. Drug-nucleic acid interactions: conformational flexibility at the intercalation site.

    PubMed Central

    Berman, H M; Neidle, S; Stodola, R K

    1978-01-01

    The conformational features of the intercalation site in polynucleotides were examined. We found that, for all the crystal structures of drug-dinucleoside complexes studied thus far, two torsion angles differ from those found in A RNA (phi and chi) and that alternate sugar puckering is not a prerequisite for intercalation. This intercalation geometry, which is the basis of helix axis displacement in a polymer, would necessitate conformational changes in the adjacent nucleotides. The base-turn angle is less sensitive to the conformation of the backbone than it is to small alterations in the base-pairing geometry. We postulate that this angle is dependent on the nature of the intercalating drug. PMID:273246

  12. Selective intercalation of o-phenylene diamine into molybdenum oxide layers

    SciTech Connect

    Shao Ke Cao Huiqun; Qiu Qi

    2009-03-05

    o-Phenylene diamine molecules were intercalated into molybdenum oxide layers by an in situ co-precipitation method. The structure and composition of the intercalated material were studied by X-ray diffraction (XRD), infrared spectroscopy (IR) and elemental analysis. XRD data evidenced a layered structure with a spacing of 18 A, which corresponds to an organic-inorganic hybrid-layered structure. IR and UV-vis spectra indicated the polymerization of o-phenylene between the molybdenum oxide layers. It was also observed that compared with aniline molecules, o-phenylene diamine molecules can be selectively intercalated into molybdenum oxide layers. We provide evidence that affinity for o-phenylene diamine to form intermolecular polymers is the reason for its selective intercalation. The polymer chain structure of o-phenylene diamine makes it a preferential guest species compared with aniline. We believe that this opens a new way to create organic-inorganic hybrid structures.

  13. Momentum shift of Dirac cones in the silicene-intercalated compound CaSi2

    NASA Astrophysics Data System (ADS)

    Dutta, Sudipta; Wakabayashi, Katsunori

    2015-05-01

    Recent experimental realization of CaSi2 paves the way of restoring the Dirac dispersion in layered materials by means of intercalation [E. Noguchi et al., Adv. Mater. 27, 856 (2015), 10.1002/adma.201403077]. Here we investigate this new material with several possible stacking sequences within ab initio calculations. The robust Dirac dispersion, a characteristic of monolayer honeycomb lattice, moves below the Fermi energy due to electron doping of silicene layers by intercalated Ca atoms. Moreover, the Dirac cone shifts away from the high symmetric point of the hexagonal Brillouin zone with the opening of a small gap. This happens due to the sublattice symmetry breaking and consequent enhanced asymmetric interlayer hopping, enforced by the enhanced buckling of the honeycomb layers. Our further studies on Ca intercalated multilayer germanene compound provide the microscopic understanding of the Dirac electrons in intercalated buckled layered materials.

  14. Intercalating dyes for enhanced contrast in second-harmonic generation imaging of protein crystals

    PubMed Central

    Newman, Justin A.; Scarborough, Nicole M.; Pogranichniy, Nicholas R.; Shrestha, Rashmi K.; Closser, Richard G.; Das, Chittaranjan; Simpson, Garth J.

    2015-01-01

    The second-harmonic generation (SHG) activity of protein crystals was found to be enhanced by up to ∼1000-fold by the intercalation of SHG phores within the crystal lattice. Unlike the intercalation of fluorophores, the SHG phores produced no significant background SHG from solvated dye or from dye intercalated into amorphous aggregates. The polarization-dependent SHG is consistent with the chromophores adopting the symmetry of the crystal lattice. In addition, the degree of enhancement for different symmetries of dyes is consistent with theoretical predictions based on the molecular nonlinear optical response. Kinetics studies indicate that intercalation arises over a timeframe of several minutes in lysozyme, with detectable enhancements within seconds. These results provide a potential means to increase the overall diversity of protein crystals and crystal sizes amenable to characterization by SHG microscopy. PMID:26143918

  15. Intercalation of Layered Silicates, Layered Double Hydroxides, and Lead Iodide: Synthesis, Characterization and Properties.

    NASA Astrophysics Data System (ADS)

    Mehrotra, Vivek

    Layered silicates, layered double hydroxides, and lead iodide are lamellar solids that can incorporate guest species into the galleries between their layers. Various intercalated forms of these layered materials have been synthesized and their properties studied. The dielectric behavior of pristine fluorohectorite, a typical layered silicate, and Zn-Al layered double hydroxide is explained by considering the structural ordering and mobility of the intercalated water molecules, as well as models invoking fractal time processes and fractal structure. Intercalative polymerization of aniline and pyrrole into fluorohectorite leads to a multilayered structure consisting of single polymer chains alternately stacked with the 9.6 A thick silicate layers. The polymer chains are confined to the quasi two-dimensional interlayer space between the rigid host layers. The hybrid films exhibit highly anisotropic properties. The optical, electrical and mechanical behavior is discussed in terms of the molecular confinement of the polymer chains. Ethylenediamine functionalized C _{60} clusters have also been intercalated into fluorohectorite via an ion-exchange procedure. Intercalation results in an improved thermal stability of the functionalized C_{60} clusters. Rutherford backscattering spectrometry has been used to elucidate the mechanism of intercalative ion exchange of silver in muscovite mica, a layered silicate with a layer charge density of 2e per unit cell. It is proposed that ion-exchange progresses by intercalating successive galleries through the edges of the mica layers. Guest-host interactions have been studied in the system aniline-PbI_2. The optical and structural effects of aniline intercalation in lead iodide thin films is discussed. Intercalation leads to a large shift in the optical band gap of PbI_2. The observed change in band gap is not only due to the increased separation between the PbI_2 layers but also because of an electrostatic interaction between the

  16. Worldwide Discoveries Help People Everywhere

    MedlinePlus

    ... Home Current Issue Past Issues Special Section Worldwide Discoveries Help People Everywhere Past Issues / Spring 2008 Table ... shows examples of discoveries and their impact. Diseases Discoveries The Benefits for All Americans Huntington's Disease Venezuela— ...

  17. Purposive discovery of operations

    NASA Technical Reports Server (NTRS)

    Sims, Michael H.; Bresina, John L.

    1992-01-01

    The Generate, Prune & Prove (GPP) methodology for discovering definitions of mathematical operators is introduced. GPP is a task within the IL exploration discovery system. We developed GPP for use in the discovery of mathematical operators with a wider class of representations than was possible with the previous methods by Lenat and by Shen. GPP utilizes the purpose for which an operator is created to prune the possible definitions. The relevant search spaces are immense and there exists insufficient information for a complete evaluation of the purpose constraint, so it is necessary to perform a partial evaluation of the purpose (i.e., pruning) constraint. The constraint is first transformed so that it is operational with respect to the partial information, and then it is applied to examples in order to test the generated candidates for an operator's definition. In the GPP process, once a candidate definition survives this empirical prune, it is passed on to a theorem prover for formal verification. We describe the application of this methodology to the (re)discovery of the definition of multiplication for Conway numbers, a discovery which is difficult for human mathematicians. We successfully model this discovery process utilizing information which was reasonably available at the time of Conway's original discovery. As part of this discovery process, we reduce the size of the search space from a computationally intractable size to 3468 elements.

  18. Room-Temperature Fluorine-Induced Decrease in the Stability of Bromine and Iodine Intercalated Carbon Fibers

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheh

    1995-01-01

    Upon exposure to room-temperature fluorine, intercalated carbon fibers (containing either bromine alone or iodine and bromine together) become heavier and less stable. For Amoco P-100 graphitized carbon fibers, which were intercalated with 18 wt percent bromine, 1 hour of fluorine exposure resulted in a large weight increase but caused only a small decrease in thermal stability. An additional 89 hours of fluorine exposure time resulted in small additional increases in fiber weight, but significant further decreases in fiber thermal stability. Such phenomena of weight increase and stability decrease do not occur if the intercalated fibers are exposed to 250 C fluorine. These observations suggest that, at room temperature, fluorine is absorbed quickly by the intercalated fibers and is intercalated slowly into the fibers. Most of the original intercalates are replaced by fluorine in the process of fluorine intercalation. In an inert environment, the bromine intercalated fibers are much more thermally stable. After 800 C vacuum heating for 2 weeks, the brominated fibers lost about 45% of their bromine, and their resistivity increased from 64 mu(Omega)-cm to a range of 95-170 mu(Omega)-cm. This is still much lower than the value of 300 mu(Omega)-cm for pristine P-100. For practical purposes, to preserve their thermal stability, brominated fibers need to be protected from exposure to fluorine at room temperature or to any intercalate at a temperature where, upon direct contact with graphite, an intercalation compound can easily be formed.

  19. Evolution of interfacial intercalation chemistry on epitaxial graphene/SiC by surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ferralis, Nicola; Carraro, Carlo

    2014-11-01

    A rapid and facile evaluation of the effects of physical and chemical processes on the interfacial layer between epitaxial graphene monolayers on SiC(0 0 0 1) surfaces is essential for applications in electronics, photonics, and optoelectronics. Here, the evolution of the atomic scale epitaxial graphene-buffer-layer-SiC interface through hydrogen intercalation, thermal annealings, UV-ozone etching and oxygen exposure is studied by means of single microparticle mediated surface enhanced Raman spectroscopy (smSERS). The evolution of the interfacial chemistry in the buffer layer is monitored through the Raman band at 2132 cm-1 corresponding to the Sisbnd H stretch mode. Graphene quality is monitored directly by the selectively enhanced Raman signal of graphene compared to the SiC substrate signal. Through smSERS, a simultaneous correlation between optimized hydrogen intercalation in epitaxial graphene/SiC and an increase in graphene quality is uncovered. Following UV-ozone treatment, a fully hydrogen passivated interface is retained, while a moderate degradation in the quality of the hydrogen intercalated quasi-freestanding graphene is observed. While hydrogen intercalated defect free quasi-freestanding graphene is expected to be robust upon UV-ozone, thermal annealing, and oxygen exposure, ozonolytic reactivity at the edges of H-intercalated defected graphene results in enhanced amorphization of the quasi-freestanding (compared to non-intercalated) graphene, leading ultimately to its complete etching.

  20. In situ intercalation dynamics in inorganic-organic layered perovskite thin films.

    PubMed

    Ahmad, Shahab; Kanaujia, Pawan K; Niu, Wendy; Baumberg, Jeremy J; Vijaya Prakash, G

    2014-07-01

    The properties of layered inorganic semiconductors can be manipulated by the insertion of foreign molecular species via a process known as intercalation. In the present study, we investigate the phenomenon of organic moiety (R-NH3I) intercalation in layered metal-halide (PbI2)-based inorganic semiconductors, leading to the formation of inorganic-organic (IO) perovskites [(R-NH3)2PbI4]. During this intercalation strong resonant exciton optical transitions are created, enabling study of the dynamics of this process. Simultaneous in situ photoluminescence (PL) and transmission measurements are used to track the structural and exciton evolution. On the basis of the experimental observations, a model is proposed which explains the process of IO perovskite formation during intercalation of the organic moiety through the inorganic semiconductor layers. The interplay between precursor film thickness and organic solution concentration/solvent highlights the role of van der Waals interactions between the layers, as well as the need for maintaining stoichiometry during intercalation. Nucleation and growth occurring during intercalation matches a Johnson-Mehl-Avrami-Kolmogorov model, with results fitting both ideal and nonideal cases. PMID:24905435

  1. Optical properties of NbCl5 and ZnMg intercalated graphite compounds

    NASA Astrophysics Data System (ADS)

    Jung, Eilho; Lee, Seokbae; Roh, Seulki; Meng, Xiuqing; Tongay, Sefaattin; Kang, Jihoon; Park, Tuson; Hwang, Jungseek

    2014-12-01

    We studied NbCl5 and ZnMg alloy intercalated graphite compounds using an optical spectroscopy technique. These intercalated metallic graphite samples were quite challenging to obtain optical reflectance spectra since they were not flat and quite thin. By using both a new method and an in situ gold evaporation technique we were able to obtain reliable reflectance spectra of our samples in the far and mid infrared range (80-7000 cm-1). We extracted the optical constants including the optical conductivity and the dielectric function from the measured reflectance spectra using a Kramers-Kronig analysis. We also extracted the dc conductivity and the plasma frequencies from the optical conductivity and dielectric functions. NbCl5 intercalated graphite samples show similar optical conductivity spectra as bare highly oriented pyrolytic graphite even though there are some differences in detail. ZnMg intercalated samples show significantly different optical conductivity spectra from the bare graphite. Optical spectroscopy is one of the most reliable experimental techniques to obtain the electronic band structures of materials. The obtained optical conductivities support the recent theoretically calculated electronic band structures of NbCl5 and ZnMg intercalated graphite compounds. Our results also provide important information of electronic structures and charge carrier properties of these two new intercalated materials for applications.

  2. Intercalation and Distribution of Silver in the Transition Metal Dichalcogenide 1T-TITANIUM-DISULFIDE.

    NASA Astrophysics Data System (ADS)

    Kaluarachchi, Dayakanthi

    The intercalation and motion of silver (Ag) in partially intercalated titanium disulphide (TiS _{rm 2}) crystals were studied using a scanning Auger electron microscope with ion sputtering, a scanning electron microscope with an x-ray fluorescence attachment, an optical microscope and radioactive tracers. The x-ray fluorescence results indicated a rapid conversion of stage 1 Ag into stage 2 Ag at room temperature and a stationary behavior of the stage 2 Ag after the stage conversion was completed. The radioactive tracer results showed that stage 2 Ag was mobile during the stage 1 to stage 2 conversion and also when a crystal was being intercalated. The motion of stage 2 Ag in the bulk of a crystal was observed only when stage 1 was present in the crystal. Auger analysis with ion sputtering yielded the 3-dimensional distribution of Ag in a partially intercalated stage 2 crystal. Ag was observed to be intercalated across the crystal surface region while the bulk was intercalated only for a short distance, indicating that the Ag has a high rate of motion near the crystal surface. A stage 2 region with a high Ag concentration was observed to be unstable near the crystal surface.

  3. Synthesis of (cinnamate-zinc layered hydroxide) intercalation compound for sunscreen application

    PubMed Central

    2013-01-01

    Background Zinc layered hydroxide (ZLH) intercalated with cinnamate, an anionic form of cinnamic acid (CA), an efficient UVA and UVB absorber, have been synthesized by direct method using zinc oxide (ZnO) and cinnamic acid as the precursor. Results The resulting obtained intercalation compound, ZCA, showed a basal spacing of 23.9 Å as a result of cinnamate intercalated in a bilayer arrangement between the interlayer spaces of ZLH with estimated percentage loading of cinnamate of about 40.4 % w/w. The UV–vis absorption spectrum of the intercalation compound showed excellent UVA and UVB absorption ability. Retention of cinnamate in ZLH interlayers was tested against media usually came across with sunscreen usage to show low release over an extended period of time. MTT assay of the intercalation compound on human dermal fibroblast (HDF) cells showed cytotoxicity of ZCA to be concentration dependent and is overall less toxic than its precursor, ZnO. Conclusions (Cinnamate-zinc layered hydroxide) intercalation compound is suitable to be used as a safe and effective sunscreen with long UV protection effect. PMID:23383738

  4. Facile synthesis of deoxycholate intercalated layered double hydroxide nanohybrids via a coassembly process

    SciTech Connect

    Wu, Xiaowen; Wang, Shuang; Du, Na; Zhang, Renjie; Hou, Wanguo

    2013-07-15

    In this paper, we describe a synthesis strategy of deoxycholate (DC) intercalated layered double hydroxide (LDH) nanohybrids via a coassembly method at room temperature. For this strategy, LDH particles were delaminated to well-dispersed 2D nanosheets in formamide, and the resulting LDH nanosheets were then coassembled with DC anions into the DC intercalated LDH (DC-LDH) nanohybrids. The so-synthesized nanohybrids were characterized by XRD, TEM, FT-IR, elemental analyses and TG-DSC. It was found that the loading amount of DC in the nanohybrids could be easily controlled by changing the ratio of DC to LDH. In addition, the nanohybrids have similar characteristics with the DC-LDH nanohybrids synthesized by the hydrothermal method, including their DC loading, crystal structure, morphology and thermal gravimetric behavior. However, this strategy exhibited the advantages of short reaction time and mild experimental conditions compared with the hydrothermal method. - Graphical abstract: Deoxycholate intercalated layered double hydroxide nanohybrids were successfully synthesized via a coassembly strategy. In this strategy, the interlayer spaces of LDHs can be efficiently used for the intercalation of guest species. - Highlights: • Deoxycholate intercalated layered double hydroxide nanohybrids were synthesized via a coassembly strategy. • This strategy exhibited the advantages of short time and mild conditions. • This strategy can enable organic species to be readily intercalated into the LDH galleries.

  5. Early stage intercalation of doxorubicin to DNA fragments observed in molecular dynamics binding simulations.

    PubMed

    Lei, Hongxing; Wang, Xiaofeng; Wu, Chun

    2012-09-01

    The intercalation mode between doxorubicin (an anticancer drug) and two 6-base-pair DNA model fragments (d(CGATCG)₂ and d(CGTACG)₂) has been well studied by X-ray crystallography and NMR experimental methods. Yet, the detailed intercalation pathway at molecular level remains elusive. In this study, we conducted molecular dynamics binding simulations of these two systems using AMBER DNA (parmbsc0) and drug (GAFF) force fields starting from the unbound state. We observed outside binding (minor groove binding or end-binding) in all six independent binding simulations (three for each DNA fragment), followed by the complete intercalation of a drug molecule in two simulations (one for each DNA fragment). First, our data directly supported that the minor groove binding is the dominant pre-intercalation step. Second, we observed that the opening and flipping of a local base pair (A3-T10 for d(CGATCG)₂ and C1-G12 for d(CGTACG)₂) in the two intercalation trajectories. This locally cooperative flipping-intercalation mechanism was different from the previously proposed rise-insertion mechanism by which the distance between two neighboring intact base pairs increases to create a space for the drug insertion. Third, our simulations provided the first set of data to support the applicability of the AMBER DNA and drug force fields in drug-DNA atomistic binding simulations. Implications on the kinetics pathway and drug action are also discussed. PMID:23079648

  6. Sugar-anionic clay composite materials: intercalation of pentoses in layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Aisawa, Sumio; Hirahara, Hidetoshi; Ishiyama, Kayoko; Ogasawara, Wataru; Umetsu, Yoshio; Narita, Eiichi

    2003-09-01

    The intercalation of non-ionized guest pentoses (ribose and 2-deoxyribose) into the Mg-Al and Zn-Al layered double hydroxides (LDHs) was carried out at 298 K by the calcination-rehydration reaction using the Mg-Al and Zn-Al oxide precursors calcined at 773 K. The resulting solid products reconstructed the LDH structure with incorporating pentoses, and the maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 20 times that by the Zn-Al oxide precursor. The ribose/Mg-Al LDH was observed to have the expanded LDH structure with a broad (003) spacing of 0.85 nm. As the thickness of the LDH hydroxide basal layer is 0.48 nm, the interlayer distance of the ribose/Mg-Al LDH is 0.37 nm. This value corresponds to molecular size of ribose in thickness (0.36 nm), supporting that ribose is horizontally oriented in the interlayer space of LDH. The maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 5 times that of 2-deoxyribose. Ribose is substituted only by the hydroxyl group at C-2 position for 2-deoxyribose. Therefore, the number of hydroxyl group of sugar is essentially important for the intercalation of sugar molecule into the LDH, suggesting that the intercalation behavior of sugar for the LDH was greatly influenced by hydrogen bond between hydroxyl group of the intercalated pentose and the LDH hydroxide basal layers.

  7. In Situ Intercalation Dynamics in Inorganic–Organic Layered Perovskite Thin Films

    PubMed Central

    2014-01-01

    The properties of layered inorganic semiconductors can be manipulated by the insertion of foreign molecular species via a process known as intercalation. In the present study, we investigate the phenomenon of organic moiety (R-NH3I) intercalation in layered metal-halide (PbI2)-based inorganic semiconductors, leading to the formation of inorganic–organic (IO) perovskites [(R-NH3)2PbI4]. During this intercalation strong resonant exciton optical transitions are created, enabling study of the dynamics of this process. Simultaneous in situ photoluminescence (PL) and transmission measurements are used to track the structural and exciton evolution. On the basis of the experimental observations, a model is proposed which explains the process of IO perovskite formation during intercalation of the organic moiety through the inorganic semiconductor layers. The interplay between precursor film thickness and organic solution concentration/solvent highlights the role of van der Waals interactions between the layers, as well as the need for maintaining stoichiometry during intercalation. Nucleation and growth occurring during intercalation matches a Johnson–Mehl–Avrami–Kolmogorov model, with results fitting both ideal and nonideal cases. PMID:24905435

  8. The Greatest Mathematical Discovery?

    SciTech Connect

    Bailey, David H.; Borwein, Jonathan M.

    2010-05-12

    What mathematical discovery more than 1500 years ago: (1) Is one of the greatest, if not the greatest, single discovery in the field of mathematics? (2) Involved three subtle ideas that eluded the greatest minds of antiquity, even geniuses such as Archimedes? (3) Was fiercely resisted in Europe for hundreds of years after its discovery? (4) Even today, in historical treatments of mathematics, is often dismissed with scant mention, or else is ascribed to the wrong source? Answer: Our modern system of positional decimal notation with zero, together with the basic arithmetic computational schemes, which were discovered in India about 500 CE.

  9. Viral surveillance and discovery

    PubMed Central

    Lipkin, Walter Ian; Firth, Cadhla

    2014-01-01

    The field of virus discovery has burgeoned with the advent of high throughput sequencing platforms and bioinformatics programs that enable rapid identification and molecular characterization of known and novel agents, investments in global microbial surveillance that include wildlife and domestic animals as well as humans, and recognition that viruses may be implicated in chronic as well as acute diseases. Here we review methods for viral surveillance and discovery, strategies and pitfalls in linking discoveries to disease, and identify opportunities for improvements in sequencing instrumentation and analysis, the use of social media and medical informatics that will further advance clinical medicine and public health. PMID:23602435

  10. Two different ground states in K-intercalated polyacenes

    NASA Astrophysics Data System (ADS)

    Phan, Quynh T. N.; Heguri, Satoshi; Tamura, Hiroyuki; Nakano, Takehito; Nozue, Yasuo; Tanigaki, Katsumi

    2016-02-01

    The electronic states of potassium- (K-) intercalated zigzag-type polycyclic aromatic (PLA) hydrocarbon [polyacene PLAs] Kx(PLAs ) are studied for a series of the four smallest molecules: naphthalene (NN), anthracene (AN), tetracene (TN), and pentacene (PN), focusing on their 1:1 stoichiometric phases. Clear experimental differences are identified between the first group [K1(NN ) and K1(AN ) ] and the second group [K1(TN ) and K1(PN ) ] by magnetic, vibrational, and optical measurements. The first group is categorized as a Mott insulator with an antiferromagnetic ground state with energy of ˜10 meV, whereas the second group is classified as a band insulator via dimer formation due to the spin Peierls instability. In the latter system, the first thermally accessible triplet states are located far apart from the singlet ground states and are not detected by electron spin-resonance spectroscopy until 300 K being very different from what is observed for the hole-doped PN reported earlier. The results give a new systematic understanding on the electronic states of electron-doped PLAs sensitive to the energetic balance among on-site Coulomb repulsion, bandwidth, and the Peierls instability.

  11. Electroactive intercalators for DNA analysis on microchip electrophoresis.

    PubMed

    Castaño-Alvarez, Mario; Fernández-Abedul, M Teresa; Costa-García, Agustín

    2007-12-01

    Miniaturized analytical systems, especially microchip CE (MCE), are becoming a promising tool for analytical purposes including DNA analysis. These microdevices require a sensitive and miniaturizable detection system such as electrochemical detection (ED). Several electroactive DNA intercalators, including the organic dye methylene blue (MB), anthraquinone derivatives, and the metal complexes Fe(phen)3 2+ and Ru(phen)3 2+, have been tested for using in combination with thermoplastic olefin polymer of amorphous structure (Topas) CE-microchips and ED. Two end-channel approaches for integration of gold wire electrodes in CE-ED microchip were used. A 250 microm diameter gold wire was manually aligned at the outlet of the separation channel. A new approach based on a guide channel for integration of 100 and 50 microm diameter gold wire has been also developed in order to reduce the background current and the baseline noise level. Modification of gold wire electrodes has been also tested to improve the detector performance. Application of MCE-ED for ssDNA detection has been studied and demonstrated for the first time using the electroactive dye MB. Electrostatic interaction between cationic MB and anionic ssDNA was used for monitoring the DNA on microchips. Thus, reproducible calibration curves for ssDNA were obtained. This study advances the feasibility of direct DNA analysis using CE-microchip with ED. PMID:18004710

  12. First-principles study of Se-intercalated graphite

    SciTech Connect

    BARTKOWIAK,M.; MODINE,NORMAND A.; SOFO,J.O.; MAHAN,G.D.

    2000-05-11

    Se-intercalated graphite compounds (Se-GICs) are considered as promising candidates for room-temperature thermoelectric cooling devices. Here the authors analyze the crystallographic structure and electronic properties of these materials within the framework of density-functional theory. First, the Adaptive-Coordinate Real-space Electronic Structure (ACRES) code is used to determine the stable structure of a representative stage-2 Se-GIC by relaxing atomic positions. The stable configuration is found to be a pendant-type structure, in which each selenium is bonded covalently to two atoms within the same carbon layer, causing a local distortion of the in-plane conjugation of the graphite. Then, they use the full potential linearized augmented plane wave (FP-LAPW) method to calculate the electronic band structure of the material and discuss its properties. Near the Fermi energy E{sub F}, there are wide bands originating from the host graphitic electronic structure and a few very narrow bands mainly of Se 4p character. The latter bands contribute to high peaks in the density of states close to E{sub F}. They show that this feature, although typical of many good thermoelectrics, does not necessarily imply high thermopower in the case of Se-GICs.

  13. Preparation and Properties of Clay/SEBS Intercalated Composites

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tomohiro; Yamada, Eisuke

    Clay/polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymer (SEBS) intercalated composites were prepared by melt-blending. The clays were a pristine montmorillonite (Mt) and three organically modified montmorillonites (organo-Mts) with different amounts of distearyldimethylammonium (D18) cation. The amounts of D18 were 50, 70 and 100% of the cation exchange capacity (denoted as D18Mt(50), D18Mt(70) and D18Mt(100), respectively). The clay/SEBS composites were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD). The dynamic mechanical analysis (DMA) and the tensile properties were also examined. The size of agglomerated clay particles decreased with the increasing amount of D18. The FE-SEM image of D18Mt(100)/SEBS revealed that the clay particles were dispersed at the sub-μm level (100-500 nm). The XRD patterns suggested that the SEBS chains were inserted into the interlayers of the organo-Mts. The DMA curves indicated that the addition of the organo-Mts produced an increase in the storage modulus in the rubbery plateau region, but a slight decrease in the glass transition temperature of the polystyrene domains. The tensile properties of the organo-Mt/SEBS composites were higher than those of the unmodified Mt/SEBS. D18Mt(100)/SEBS displayed an improved tensile modulus, tear strength and hardness compared to pure SEBS, without sacrificing the tensile strength and elongation at break.

  14. NASA's Discovery Program

    NASA Astrophysics Data System (ADS)

    Kicza, Mary; Bruegge, Richard Vorder

    1995-01-01

    NASA's Discovery Program represents an new era in planetary exploration. Discovery's primary goal: to maintain U.S. scientific leadership in planetary research by conducting a series of highly focused, cost effective missions to answer critical questions in solar system science. The Program will stimulate the development of innovative management approaches by encouraging new teaming arrangements among industry, universities and the government. The program encourages the prudent use of new technologies to enable/enhance science return and to reduce life cycle cost, and it supports the transfer of these technologies to the private sector for secondary applications. The Near-Earth Asteroid Rendezvous and Mars Pathfinder missions have been selected as the first two Discovery missions. Both will be launched in 1996. Subsequent, competitively selected missions will be conceived and proposed to NASA by teams of scientists and engineers from industry, academia, and government organizations. This paper summarizes the status of Discovery Program planning.

  15. The requirements discovery process

    SciTech Connect

    Bahill, A.T.; Dean, F.F.

    1997-02-01

    Cost and schedule overruns are often caused by poor requirements that are produced by people who do not understand the requirement process. This paper provides a high-level overview of the requirements discovery process.

  16. The Discovery of Noggin.

    ERIC Educational Resources Information Center

    Oppenheimer, Steven B.

    1995-01-01

    Discusses recently published work that appears to have many of the answers to the question of how the nervous system develops. Focuses on the discovery of what is believed to be neural inducer, a protein called noggin. (LZ)

  17. Toxins and drug discovery.

    PubMed

    Harvey, Alan L

    2014-12-15

    Components from venoms have stimulated many drug discovery projects, with some notable successes. These are briefly reviewed, from captopril to ziconotide. However, there have been many more disappointments on the road from toxin discovery to approval of a new medicine. Drug discovery and development is an inherently risky business, and the main causes of failure during development programmes are outlined in order to highlight steps that might be taken to increase the chances of success with toxin-based drug discovery. These include having a clear focus on unmet therapeutic needs, concentrating on targets that are well-validated in terms of their relevance to the disease in question, making use of phenotypic screening rather than molecular-based assays, and working with development partners with the resources required for the long and expensive development process. PMID:25448391

  18. Discovery Touches Down!

    NASA Video Gallery

    Discovery has completed its final mission, STS-133, for NASA's Space Shuttle Program landing on-time at Kennedy Space Center in Florida at 11:57 a.m. EST, March 9, 2011 after 202 orbits around Eart...

  19. Model Evidence of an Anisotropic Chiral d+id-Wave Pairing State for the Water-Intercalated NaxCoO2·yH2O Superconductor

    NASA Astrophysics Data System (ADS)

    Kiesel, Maximilian L.; Platt, Christian; Hanke, Werner; Thomale, Ronny

    2013-08-01

    Since its discovery, the superconducting phase in water-intercalated sodium cobaltates NaxCoO2·yH2O (x˜0.3, y˜1.3) has posed fundamental challenges in terms of experimental investigation and theoretical understanding. By a combined cluster calculation and renormalization group approach, we find an anisotropic chiral d+id-wave state as a consequence of multiorbital effects, Fermi surface topology, and magnetic fluctuations. It naturally explains the singlet property and close-to-nodal gap features of the superconducting phase as indicated by experiments.

  20. The intercalation of bicyclic and tricyclic carboxylates into layered double hydroxides

    SciTech Connect

    Khan, Aamir I.; Williams, Gareth R.; Hu, Gang; Rees, Nicholas H.; O'Hare, Dermot

    2010-12-15

    Twenty-four nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised for the first time. Eight carboxylates were successfully intercalated into [LiAl{sub 2}(OH){sub 6}]Cl.yH{sub 2}O, [Ca{sub 2}Al(OH){sub 6}]NO{sub 3}.yH{sub 2}O, and [Mg{sub 2}Al(OH){sub 6}]NO{sub 3}.yH{sub 2}O, and the products fully characterised. Guest species incorporated include 1-adamantane carboxylate (1-AC) and 5-norbornene-2-endo-3-exo-dicarboxylate. In some cases, carbonate anions were co-intercalated with the organic guest, and in others poorly crystalline aluminium hydroxides formed as by-products. Sharper resonances were observed in the {sup 13}C solid-state NMR spectra of the 1-AC intercalates than in the spectrum of pure 1-AC, suggesting increased order in the arrangement of the cyclic cages in the intercalates. Where possible, time-resolved in situ X-ray diffraction was employed to study the nanoscopic steps involved in the intercalation reactions. These investigations showed that the reactions are one-step processes, proceeding directly to the fully exchanged intercalate with no intermediate phases. The intercalation processes were found to be nucleation controlled. -- Graphical abstract: Twenty-four novel nanocomposites built from layered double hydroxides and bicyclic and tricyclic carboxylates have been synthesised and fully characterised. In situ X-ray diffraction was used to study reaction mechanisms and kinetics. Display Omitted

  1. Enhancement of the superconducting transition temperature of FeSe by intercalation of a molecular spacer layer

    NASA Astrophysics Data System (ADS)

    Burrard-Lucas, Matthew; Free, David G.; Sedlmaier, Stefan J.; Wright, Jack D.; Cassidy, Simon J.; Hara, Yoshiaki; Corkett, Alex J.; Lancaster, Tom; Baker, Peter J.; Blundell, Stephen J.; Clarke, Simon J.

    2013-01-01

    The discovery of high-temperature superconductivity in a layered iron arsenide has led to an intensive search to optimize the superconducting properties of iron-based superconductors by changing the chemical composition of the spacer layer between adjacent anionic iron arsenide layers. Superconductivity has been found in iron arsenides with cationic spacer layers consisting of metal ions (for example, Li+, Na+, K+, Ba2+) or PbO- or perovskite-type oxide layers, and also in Fe1.01Se (ref. ) with neutral layers similar in structure to those found in the iron arsenides and no spacer layer. Here we demonstrate the synthesis of Lix(NH2)y(NH3)1-yFe2Se2 (x~0.6 y~0.2), with lithium ions, lithium amide and ammonia acting as the spacer layer between FeSe layers, which exhibits superconductivity at 43(1) K, higher than in any FeSe-derived compound reported so far. We have determined the crystal structure using neutron powder diffraction and used magnetometry and muon-spin rotation data to determine the superconducting properties. This new synthetic route opens up the possibility of further exploitation of related molecular intercalations in this and other systems to greatly optimize the superconducting properties in this family.

  2. Large Intercalated Neurons of Amygdala Relay Noxious Sensory Information

    PubMed Central

    Bienvenu, Thomas C.M.; Busti, Daniela; Micklem, Benjamin R.; Mansouri, Mahnaz; Magill, Peter J.

    2015-01-01

    Various GABAergic neuron types of the amygdala cooperate to control principal cell firing during fear-related and other behaviors, and understanding their specialized roles is important. Among GABAergic neurons, the so-called intercalated cells (ITCcs) are critically involved in the expression and extinction of fear memory. Tightly clustered small-sized spiny neurons constitute the majority of ITCcs, but they are surrounded by sparse, larger neurons (L-ITCcs) for which very little information is known. We report here a detailed neurochemical, structural and physiological characterization of rat L-ITCcs, as identified with juxtacellular recording/labeling in vivo. We supplement these data with anatomical and neurochemical analyses of nonrecorded L-ITCcs. We demonstrate that L-ITCcs are GABAergic, and strongly express metabotropic glutamate receptor 1α and GABAA receptor α1 subunit, together with moderate levels of parvalbumin. Furthermore, L-ITCcs are innervated by fibers enriched with metabotropic glutamate receptors 7a and/or 8a. In contrast to small-sized spiny ITCcs, L-ITCcs possess thick, aspiny dendrites, have highly branched, long-range axonal projections, and innervate interneurons in the basolateral amygdaloid complex. The axons of L-ITCcs also project to distant brain areas, such as the perirhinal, entorhinal, and endopiriform cortices. In vivo recorded L-ITCcs are strongly activated by noxious stimuli, such as hindpaw pinches or electrical footshocks. Consistent with this, we observed synaptic contacts on L-ITCc dendrites from nociceptive intralaminar thalamic nuclei. We propose that, during salient sensory stimulation, L-ITCcs disinhibit local and distant principal neurons, acting as “hub cells,” to orchestrate the activity of a distributed network. PMID:25653362

  3. High transition temperatures in molecular intercalates of FeSe

    NASA Astrophysics Data System (ADS)

    Blundell, Stephen

    2015-03-01

    Molecular groups can now be intercalated into iron-based superconductors with dramatic consequences on the superconducting properties. These species act as charge reservoirs, sources of electrical polarization, and also make subtle structural modifications to superconducting layers, all of which can make novel adjustments to the band structure that in turn can control superconducting properties. By synthesizing the compound Lix(NH2)y(NH3)1 -yFe2Se2 (x ~ 0.6; y ~ 0.2), in which lithium ions, lithium amide and ammonia (NH3) act as the spacer layer between FeSe layers, we have turned a 9 K superconductor into a 43 K superconductor. Further chemical modification allow us to produce a range of new superconducting materials which we have studied using a variety of techniques including muon-spin rotation. Recently, we have used hydrothermal reactions to produce layered lithium iron selenide hydroxides with chemical formula Li1-xFex(OH)Fe1-ySe and thereby producing compounds whose transition temperature can be tuned from zero up to about 40 K. Minimizing the concentration of iron vacancies in the iron selenide layer and simultaneously increasing the electron count on iron in the selenide layers enhance the superconducting properties in this family. Future prospects for new superconducting materials using these novel synthetic routes will be discussed, as will also our current understanding of the superconductivity in these materials. (Work performed in collaboration with S. J. Clarke and coworkers at Oxford, RAL and Durham, UK.) Work supported by EPSRC(UK).

  4. Cobalt intercalation at the graphene/iridium(111) interface: Influence of rotational domains, wrinkles, and atomic steps

    SciTech Connect

    Vlaic, S.; Kimouche, A.; Coraux, J.; Rougemaille, N.; Santos, B.; Locatelli, A.

    2014-03-10

    Using low-energy electron microscopy, we study Co intercalation under graphene grown on Ir(111). Depending on the rotational domain of graphene on which it is deposited, Co is found intercalated at different locations. While intercalated Co is observed preferentially at the substrate step edges below certain rotational domains, it is mostly found close to wrinkles below other domains. These results indicate that curved regions (near substrate atomic steps and wrinkles) of the graphene sheet facilitate Co intercalation and suggest that the strength of the graphene/Ir interaction determines which pathway is energetically more favorable.

  5. A Decade of Discovery

    SciTech Connect

    2008-01-01

    This book provides a fascinating account of some of the most significant scientific discoveries and technological innovations coming out of the U.S. Department of Energy’s National Laboratories. This remarkable book illustrates how the men and women of the National Laboratories are keeping us on the cutting edge. Though few Americans are familiar with the scope and scale of the work conducted at these National Laboratories, their research is literally changing our lives and bettering our planet. The book describes the scientific discoveries and technological advancements "in recognition of the men and women working in DOE's seventeen national laboratories across the country." Through highly vivid and accessible stories, this book details recent breakthroughs in three critical areas: 1) Energy and Environment, 2) National Security and 3) Life and Physical Science. The book illustrates how this government-funded research has resulted in more energy-efficient buildings; new, cleaner alternative fuels that reduce greenhouse gas emissions; safer, more efficient, nuclear power plants; improved responses to disease outbreaks; more secure and streamlined airport security; more effective treatments for cancer and other diseases; and astonishing discoveries that are altering our understanding of the universe and enabling scientific breakthroughs in fields such as nanotechnology and particle physics. Specifically, it contains 37 stories. A Decade of Discovery is truly a recent history of discovery - and a fascinating look at what the next decade holds.

  6. DB DISCOVERY. Discovery Programs for SBH Experiments

    SciTech Connect

    Milosavljevic, A.

    1992-12-01

    DB DISCOVERY is a suite of programs for analyzing results of SBH experiments and for discovering patterns and correlations with the existing sequence data. The bundles of data that are analyzed as a unit are prepared by DB EXP ASSEMBLY programs. The DB DISCOVERY programs are written in the UNIX shell style and execute in the context of the database. The data in the database are accessed through the Sybase db-library. The programs are typically combined in UNIX shell scripts which perform particular data analysis tasks. The suite consists of the DBB, DBC, DBE, DBF, DBG, DBH programs, and an improved version of the SMPL program which is also part of the PYTHIA suite. DBB, DBC, and DBD are used to generate desired clone signatures, which consist either of hybridiztion intensities or a partial sequence. DBE discovers groups of similar clones based on their signatures. DBG, DBH, and DBF are used for analyzing the clustering information, comparing different groupings of clones, and for clustering error correction information. The improved version of SMPL compares partial sequences with known DNA sequences in order to identify already-sequenced clones and possible sequence similarities with sequenced DNA.

  7. Micromechanical properties of intercalated compounds of graphite oxide with dodecahydro- closо-dodecaboric acid

    NASA Astrophysics Data System (ADS)

    Karpenko, A. A.; Saldin, V. I.

    2016-08-01

    The micromechanical properties (Young's modulus, deformation, and adhesion) of the intercalated compound of graphite oxide with dodecahydro- closo-dodecaboric acid were studied by atomic force microscopy, transmission electron microscopy, and Raman spectroscopy and compared with the same characteristics of the starting graphite oxide. The significant difference in the micromechanical properties of the materials under study is dictated by differences in the topography and properties of their film surface, which, in turn, can be determined by their chemical composition. The introduction of dodecahydro- closo-dodecaboric acid in the interplanar space of graphite oxide affects the structuring of the latter. A considerable increase in the adhesion of the intercalated compound relative to that of oxide graphite is explained by high adhesive properties of the introduced acid, the Young's modulus of graphite oxide being higher than that of the intercalated compound. This was attributed to the high hydrophilicity of dodecahydro- closo-dodecaboric acid and the difficulty of water removal from the interplanar space; water plasticizes the material, which becomes softer than graphite oxide. The difference in the structure of the coating of the intercalated compounds and the starting graphite oxide was found to be also reflected by their Raman spectra, namely, by the increased intensity of the D line with the preserved position of the G line, which points to the impurity nature of the intercalate and the unchanged hexagonal lattice of graphite.

  8. Intercalation-assisted longitudinal unzipping of carbon nanotubes for green and scalable synthesis of graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Li, Yan-Sheng; Liao, Jia-Liang; Wang, Shan-Yu; Chiang, Wei-Hung

    2016-03-01

    We have demonstrated an effective intercalation of multi-walled carbon nanotubes (MWCNTs) for the green and scalable synthesis of graphene nanoribbons (GNRs) using an intercalation-assisted longitudinal unzipping of MWCNTs. The key step is to introduce an intercalation treatment of raw MWCNTs with KNO3 and H2SO4, making it promising to decrease the strong van der Waals attractions in the MWCNTs bundles and between the coaxial graphene walls of CNTs. Systematic micro Raman, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) characterizations suggest that potassium, nitrate, and sulfate ions play an important role in the CNT intertube and intratube intercalations during the pretreatment. Detailed scanning electron microscopy (SEM), transmission electron microscopy, XRD, and micro Raman characterizations indicate that the developed methodology possesses the ability to synthesis GNRs effectively with an improved CNT concentration in H2SO4 of 10 mg/ml at 70 °C, which is amenable to industrial-scale production because of the decreased amount of strong acid. Our work provides a scientific understanding how to enhance the GNR formation by accelerating the CNT longitudinal unzipping via suitable molecular intercalation.

  9. Proton enhanced scattering and nuclear reaction analysis microcharacterization of ternary graphite-lithium-calcium intercalation compounds

    NASA Astrophysics Data System (ADS)

    Berger, P.; Pruvost, S.; Hérold, C.; Lagrange, P.

    2004-06-01

    Intercalation of lithium into graphite is of great interest, due to its largely expanded use as negative electrode material in the Li-ion batteries, especially the LiC 6 compound. Recently, the first ternary intercalation compounds associating lithium with a second metallic element were synthesized by immersing pyrographite platelet in a molten Ca-Li alloy. Photonic and neutronic diffractions on these graphite-lithium-calcium compounds reveal that lithium and calcium layers are intercalated between graphene sheets. However, the precise elemental composition still lacks. Chemical analysis gives an average composition but carbon is not measured in the same sample as calcium and lithium. Electron microprobe, SEM and TEM do not allow to determine lithium concentration and its distribution in these compounds. This paper reports the first elemental characterization of carbon-calcium-lithium intercalation compounds by means of nuclear microprobe. Using a 3.1 MeV proton beam, both lithium, calcium and carbon can be determined within a single measurement, from the 7Li(p,α) 4He nuclear reaction and from elastic scattering for calcium and carbon respectively. In the graphite-lithium-calcium system, three different intercalation compounds were synthesized, containing low to high lithium content. The mapping of the samples reveals lateral and also mainly in depth heterogeneity (along the c axis).

  10. Direct intercalation of cisplatin into zirconium phosphate nanoplatelets for potential cancer nanotherapy

    PubMed Central

    Díaz, Agustín; González, Millie L.; Pérez, Riviam J.; David, Amanda; Mukherjee, Atashi; Báez, Adriana; Clearfield, Abraham

    2014-01-01

    We report the use of zirconium phosphate nanoplatelets (ZrP) for the encapsulation of the anticancer drug cisplatin and its delivery to tumor cells. Cisplatin was intercalated into ZrP by direct-ion exchange and was tested in-vitro for cytotoxicity in the human breast cancer (MCF-7) cell line. The structural characterization of the intercalated cisplatin in ZrP suggests that during the intercalation process, the chloride ligands of the cisplatin complex were substituted by phosphate groups within the layers. Consequently, a new phosphate phase with the platinum complex directly bound to ZrP (cisPt@ZrP) is produced with an interlayer distance of 9.3 Å. The in-vitro release profile of the intercalated drug by pH stimulus shows that at low pH under lysosomal conditions the platinum complex is released with simultaneous hydrolysis of the zirconium phosphate material, while at higher pH the complex is not released. Experiments with the MCF-7 cell line show that cisPt@ZrP reduced the cell viability up to 40%. The cisPt@ZrP intercalation product is envisioned as a future nanotherapy agent for cancer. Taking advantage of the shape and sizes of the ZrP particles and controlled release of the drug at low pH, it is intended to exploit the enhanced permeability and retention effect of tumors, as well as their intrinsic acidity, for the destruction of malignant cells. PMID:24072038

  11. Li Intercalation into Graphite: Direct Optical Imaging and Cahn-Hilliard Reaction Dynamics.

    PubMed

    Guo, Yinsheng; Smith, Raymond B; Yu, Zhonghua; Efetov, Dmitri K; Wang, Junpu; Kim, Philip; Bazant, Martin Z; Brus, Louis E

    2016-06-01

    Lithium intercalation into graphite is a critical process in energy storage technology. Studies of Li intercalation kinetics have proved challenging due to structural and phase complexity, and sample heterogeneity. Here we report direct time- and space-resolved, all-optical measurement of Li intercalation. We use a single crystal graphite electrode with lithographically defined disc geometry. All-optical, Raman and reflectance measurements distinguish the intrinsic intercalation process from side reactions, and provide new insight into the microscopic intercalation process. The recently proposed Cahn-Hilliard reaction (CHR) theory quantitatively captures the observed phase front spatial patterns and dynamics, using a two-layer free-energy model with novel, generalized Butler-Volmer kinetics. This approach unites Cahn-Hilliard and electrochemical kinetics, using a thermodynamically consistent description of the Li injection reaction at the crystal edge that involves a cooperative opening of graphene planes. The excellent agreement between experiment and theory presented here, with single-crystal resolution, provides strong support for the CHR theory of solid-state reactions. PMID:27203128

  12. Scalable production of graphene with tunable and stable doping by electrochemical intercalation and exfoliation.

    PubMed

    Hsieh, Ya-Ping; Chiang, Wan-Yu; Tsai, Sun-Lin; Hofmann, Mario

    2016-01-01

    Graphene's unique semimetallic band structure yields carriers with widely tunable energy levels that enable novel electronic devices and energy generators. To enhance the potential of this feature, a scalable synthesis method for graphene with adjustable Fermi levels is required. We here show that the electrochemical intercalation of FeCl3 and subsequent electrochemical exfoliation produces graphene whose energy levels can be finely tuned by the intercalation parameters. X-ray photoelectron spectroscopy reveals that a gradual transition in the bonding character of the intercalant is the source of this behavior. The intercalated graphene exhibits a significantly increased work function that can be varied between 4.8 eV and 5.2 eV by the intercalation potential. Transparent conducting electrodes produced by these graphene flakes exhibit a threefold improvement in performance and the doping effect was found to be stable for more than a year. These findings open up a new route for the scalable production of graphene with adjustable properties for future applications. PMID:26617396

  13. Intercalation of organic molecules in 2D copper (II) nitroprusside: Intermolecular interactions and magnetic properties

    SciTech Connect

    Osiry, H.; Cano, A.; Lemus-Santana, A.A.; Rodríguez, A.; Carbonio, R.E.; Reguera, E.

    2015-10-15

    This contribution discusses the intercalation of imidazole and its 2-ethyl derivative, and pyridine in 2D copper nitroprusside. In the interlayer region, neighboring molecules remain interacting throu gh their dipole and quadrupole moments, which supports the solid 3D crystal structure. The crystal structure of this series of intercalation compounds was solved and refined from powder X-ray diffraction patterns complemented with spectroscopic information. The intermolecular interactions were studied from the refined crystal structures and low temperature magnetic measurements. Due to strong attractive forces between neighboring molecules, the resulting π–π cloud overlapping enables the ferromagnetic coupling between metal centers on neighboring layers, which was actually observed for the solids containing imidazole and pyridine as intercalated molecules. For these two solids, the magnetic data were properly described with a model of six neighbors. For the solid containing 2-ethylimidazole and for 2D copper nitroprusside, a model of four neighbors in a plane is sufficient to obtain a reliable data fitting. - Highlights: • Intercalation of organic molecules in 2D copper (II) nitroprusside. • Molecular properties of intercalation compounds of 2D copper (II) nitroprusside. • Magnetic properties of hybrid inorganic–organic solids. • Hybrid inorganic–organic 3D framework.

  14. High-coverage stable structures of 3d transition metal intercalated bilayer graphene.

    PubMed

    Liao, Ji-Hai; Zhao, Yu-Jun; Tang, Jia-Jun; Yang, Xiao-Bao; Xu, Hu

    2016-06-01

    Alkali-metal intercalated graphite and graphene have been intensively studied for decades, where alkali-metal atoms are found to form ordered structures at the hollow sites of hexagonal carbon rings. Using first-principles calculations, we have predicted various stable structures of high-coverage 3d transition metal (TM) intercalated bilayer graphene (BLG) stabilized by the strain. Specifically, with reference to the bulk metal, Sc and Ti can form stable TM-intercalated BLG without strain, while the stabilization of Fe, Co, and Ni intercalated BLG requires the biaxial strain of over 7%. Under the biaxial strain ranging from 0% to 10%, there are four ordered sandwich structures for Sc with the coverage of 0.25, 0.571, 0.684, and 0.75, in which the Sc atoms are all distributed homogenously instead of locating at the hollow sites. According to the phase diagram, a homogenous configuration of C8Ti3C8 with the coverage of 0.75 and another inhomogeneous structure with the coverage of 0.692 were found. The electronic and magnetic properties as a function of strain were also analyzed to indicate that the strain was important for the stabilities of the high-coverage TM-intercalated BLG. PMID:27167998

  15. Layered double hydroxides as supports for intercalation and sustained release of antihypertensive drugs

    NASA Astrophysics Data System (ADS)

    Xia, Sheng-Jie; Ni, Zhe-Ming; Xu, Qian; Hu, Bao-Xiang; Hu, Jun

    2008-10-01

    Zn/Al layered double hydroxides (LDHs) were intercalated with the anionic antihypertensive drugs Enalpril, Lisinopril, Captopril and Ramipril by using coprecipitation or ion-exchange technique. TG-MS analyses suggested that the thermal stability of Ena -, Lis - (arranged with monolayer, resulted from X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) analysis was enhanced much more than Cap - and Ram - (arranged with bilayer). The release studies show that the release rate of all samples markedly decreased in both pH 4.25 and 7.45. However, the release time of Ena -, Lis - were much longer compared with Cap -, Ram - in both pH 4.25 and 7.45, it is possible that the intercalated guests, arranged with monolayer in the interlayer, show lesser repulsive force and strong affinity with the LDH layers. And the release data followed both the Higuchi-square-root law and the first-order equation well. Based on the analysis of batch release, intercalated structural models as well as the TG-DTA results, we conclude that for drug-LDH, stronger the affinity between intercalated anions and the layers is, better the thermal property and the stability to the acid attack of drug-LDH, and the intercalated anions are easier apt to monolayer arrangement within the interlayer, were presented.

  16. Pyridine intercalated Bi2Se3 heterostructures: controlling the topologically protected states.

    PubMed

    de Oliveira, I S S; Miwa, R H

    2016-01-22

    We use ab initio simulations to investigate the incorporation of pyridine molecules (C5H5N) in the van der Waals (vdW) gaps of Bi2Se3. The intercalated pyridine molecules increase the separation distance between the Bi2Se3 quintuple layers (QLs), suppressing the parity inversion of the electronic states at the Γ-point. We find that (i) the intercalated region becomes a trivial insulator. By combining the pristine Bi2Se3 region with the one intercalated by the molecules (py-Bi2Se3), we have a trivial/topological heterojunction (py-Bi2Se3/Bi2Se3) characterized by the presence of topologically protected metallic states at the interfacial region. Next, (ii) we apply an external compressive pressure to the system, and the results are a decrease of the separation distance between the QLs intercalated by pyridine molecules, and the metallic states are shifted toward the bulk region, turning the system back to the insulator. Our findings indicate that, through the intercalation of pyridine molecules in Bi2Se3 [(i)], we may have a number of topologically protected metallic channels embedded in (py-Bi2Se3) m /(Bi2Se3) n heterostructures/superlattices, in addition, through suitable tuning of the external pressure [(ii)], we can control its topological properties, turning on and off the topologically protected metallic states in (py-Bi2Se3)m /(Bi2Se3)n. PMID:26636668

  17. Pyridine intercalated Bi2Se3 heterostructures: controlling the topologically protected states

    NASA Astrophysics Data System (ADS)

    de Oliveira, I. S. S.; Miwa, R. H.

    2016-01-01

    We use ab initio simulations to investigate the incorporation of pyridine molecules (C5H5N) in the van der Waals (vdW) gaps of Bi2Se3. The intercalated pyridine molecules increase the separation distance between the Bi2Se3 quintuple layers (QLs), suppressing the parity inversion of the electronic states at the Γ-point. We find that (i) the intercalated region becomes a trivial insulator. By combining the pristine Bi2Se3 region with the one intercalated by the molecules (py-Bi2Se3), we have a trivial/topological heterojunction (py-Bi2Se3/Bi2Se3) characterized by the presence of topologically protected metallic states at the interfacial region. Next, (ii) we apply an external compressive pressure to the system, and the results are a decrease of the separation distance between the QLs intercalated by pyridine molecules, and the metallic states are shifted toward the bulk region, turning the system back to the insulator. Our findings indicate that, through the intercalation of pyridine molecules in Bi2Se3 [(i)], we may have a number of topologically protected metallic channels embedded in (py-Bi2Se3) m /(Bi2Se3) n heterostructures/superlattices, in addition, through suitable tuning of the external pressure [(ii)], we can control its topological properties, turning on and off the topologically protected metallic states in (py-Bi2Se3) m /(Bi2Se3) n .

  18. Electrochemical Intercalation of Lithium Ions into NbSe2 Nanosheets.

    PubMed

    Hitz, Emily; Wan, Jiayu; Patel, Anand; Xu, Yue; Meshi, Louisa; Dai, Jiaqi; Chen, Yanan; Lu, Aijiang; Davydov, Albert V; Hu, Liangbing

    2016-05-11

    Transition metal dichalcogenides (TMDCs) have been known for decades to have unique properties and recently attracted broad attention for their two-dimensional (2D) characteristics. NbSe2 is a metallic TMDC that has been studied for its charge density wave transition behavior and superconductivity but is still largely unexplored for its potential use in engineered devices with applications in areas such as electronics, optics, and batteries. Thus, we successfully demonstrate and present evidence of lithium intercalation in NbSe2 as a technique capable of modifying the material properties of NbSe2 for further study. We demonstrate successful intercalation of Li ions into NbSe2 and confirm this result through X-ray diffraction, noting a unit cell size increase from 12.57 to 13.57 Å in the c lattice parameter of the NbSe2 after intercalation. We also fabricate planar half-cell electrochemical devices using ultrathin NbSe2 from platelets to observe evidence of Li-ion intercalation through an increase in the optical transmittance of the material in the visible range. Using 550 nm wavelength light, we observed an increase in optical transmittance of 26% during electrochemical intercalation. PMID:27100021

  19. Intercallation of Li1-xFexO2 in the superconducting FeSe

    NASA Astrophysics Data System (ADS)

    Louca, Despina; Yang, Junjie

    The intercallation of LiFeO2 in the tetragonal lattice of the 8 K superconductor Fe1-ySe leads to a great enhancement of the superconducting transition temperature, TC ~ 43 K, and to an antiferromagnetic transition at 8.5 K. While the LiFeO2 layer acts as a charge reservoir, its Fe3+ ion (3d5) is magnetic creating a magnetic buffer layer. Most recently, we developed a new synthesis method to control the Fe concentration in the intercallating layer as well as the filling ratio of the Li1-xFexO2 : FeSe layers. Neutron scattering measurements were carried out on powder samples of (Li1-xFexO2)yFeSe. With the intercallation, no crystal structural transition from the P4/nmm symmetry occurs but the c-axis lattice constant expands substantially, evidence of the intercallation. At the same time, the tetrahedral FeSe layers remain intact with no compression or expansion and free of vacancies. Moreover, the intercallation along the c-axis although not uniform leads to a reduction in TC when the ratio of Li1 - x FexO2 : FeSe layers is about 1 to 3. Our results also indicate that the amount of Fe in the Li1 - x FexO2 layer has a direct correlation to the transition temperature as well.

  20. Intercalation-assisted longitudinal unzipping of carbon nanotubes for green and scalable synthesis of graphene nanoribbons

    PubMed Central

    Li, Yan-Sheng; Liao, Jia-Liang; Wang, Shan-Yu; Chiang, Wei-Hung

    2016-01-01

    We have demonstrated an effective intercalation of multi-walled carbon nanotubes (MWCNTs) for the green and scalable synthesis of graphene nanoribbons (GNRs) using an intercalation-assisted longitudinal unzipping of MWCNTs. The key step is to introduce an intercalation treatment of raw MWCNTs with KNO3 and H2SO4, making it promising to decrease the strong van der Waals attractions in the MWCNTs bundles and between the coaxial graphene walls of CNTs. Systematic micro Raman, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) characterizations suggest that potassium, nitrate, and sulfate ions play an important role in the CNT intertube and intratube intercalations during the pretreatment. Detailed scanning electron microscopy (SEM), transmission electron microscopy, XRD, and micro Raman characterizations indicate that the developed methodology possesses the ability to synthesis GNRs effectively with an improved CNT concentration in H2SO4 of 10 mg/ml at 70 °C, which is amenable to industrial-scale production because of the decreased amount of strong acid. Our work provides a scientific understanding how to enhance the GNR formation by accelerating the CNT longitudinal unzipping via suitable molecular intercalation. PMID:26948486

  1. Discovery of Charm

    DOE R&D Accomplishments Database

    Goldhaber, G.

    1984-11-01

    In my talk I will cover the period 1973 to 1976 which saw the discoveries of the J/psi and psi' resonances and most of the Psion spectroscopy, the tau lepton and the D0030099,D0015599 charmed meson doublet. Occasionally I will refer briefly to more recent results. Since this conference is on the history of the weak-interactions I will deal primarily with the properties of naked charm and in particular the weakly decaying doublet of charmed mesons. Most of the discoveries I will mention were made with the SLAC-LBL Magnetic Detector or MARK I which we operated at SPEAR from 1973 to 1976.

  2. Hydroxy double salts intercalated with Mn(II) complexes as potential contrast agents

    NASA Astrophysics Data System (ADS)

    Jin, Miao; Li, Wanjing; Spillane, Dominic E. M.; Geraldes, Carlos F. G. C.; Williams, Gareth R.; Bligh, S. W. Annie

    2016-03-01

    A series of Mn(II) aminophosphonate complexes were successfully synthesized and intercalated into the hydroxy double salt [Zn5(OH)8]Cl2·yH2O. Complex incorporation led to an increase in the interlayer spacing from 7.8 to 10-12 Å. Infrared spectroscopy showed the presence of the characteristic vibration peaks of the Mn(II) complexes in the intercalates' spectra, indicating successful incorporation. The complex-loaded composites had somewhat lower proton relaxivities than the pure complexes. Nevertheless, these intercalates may have use as MRI contrast agents for patients with poor kidney function, where traditional Gd(III)-based contrast agents cause severe renal failure.

  3. Controlling the actuation properties of MXene paper electrodes upon cation intercalation

    SciTech Connect

    Come, Jeremy E.; Black, Jennifer M.; Naguib, Michael; Lukatskaya, Maria R.; Beidaghi, Majid; Wesolowski, David J.; Gogotsi, Yury; Rondinone, Adam J.; Balke, Nina; Kalinin, Sergei V.

    2015-08-05

    Atomic force microscopy was used to monitor the macroscopic deformation in a delaminated Ti₃C₂ paper electrode in-situ, during charge/discharge in a variety of aqueous electrolytes to examine the effect of the cation intercalation on the electrochemical behavior and mechanical response. The results show a strong dependence of the electrode deformation on cation size and charge. The electrode undergoes a large contraction during Li⁺, Na⁺ or Mg²⁺ intercalation, differentiating the Ti₃C₂ paper from conventional electrodes where redox intercalation of ions (e.g. Li⁺) into the bulk phase (e.g. graphite, silicon) results in volumetric expansion. This feature may explain the excellent rate performance and cyclability reported for MXenes. We also demonstrated that the variation of the electromechanical contraction can be easily adjusted by electrolyte exchange, and shows interesting characteristics for the design of actuators based on 2D metal carbides.

  4. Effect of lightning strike on bromine intercalated graphite fiber/epoxy composites

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Slabe, Melissa E.; Brink, Norman O.

    1991-01-01

    Laminar composites were fabricated from pristine and bromine intercalated pitch based graphite fibers. It was found that laminar composites could be fabricated using either pristine or intercalated graphite fibers using standard fabrication techniques. The intercalated graphite fiber composites had electrical properties which were markedly improved over both the corresponding pitch based and polyacrylonitrile (PAN) based composites. Despite composites resistivities more than an order of magnitude lower for pitch based fiber composites, the lightning strike resistance was poorer than that of the Pan based fiber composites. This leads to the conclusion that the mechanical properties of the pitch fibers are more important than electrical or thermal properties in determining the lightning strike resistance. Based on indicated lightning strike tolerance for high elongation to failure materials, the use of vapor grown, rather than pitch based graphite fibers appears promising.

  5. Electron doping through lithium intercalation to interstitial channels in tetrahedrally bonded SiC

    SciTech Connect

    Sakai, Yuki; Oshiyama, Atsushi

    2015-11-07

    We report on first-principles calculations that clarify the effect of lithium atom intercalation into zinc blende 3C-silicon carbide (3C-SiC) on electronic and structural properties. Lithium atoms inside 3C-SiC are found to donate electrons to 3C-SiC that is an indication of a new way of electron doping through the intercalation. The electrons doped into the conduction band interact with lithium cations and reduce the band spacing between the original valence and conduction bands. We have also found that a silicon monovacancy in 3C-SiC promotes the lithium intercalation, showing that the vacancy generation makes SiC as a possible anode material for lithium-ion battery.

  6. Electronic and geometric structure of graphene/SiC(0001) decoupled by lithium intercalation

    NASA Astrophysics Data System (ADS)

    Bisti, F.; Profeta, G.; Vita, H.; Donarelli, M.; Perrozzi, F.; Sheverdyaeva, P. M.; Moras, P.; Horn, K.; Ottaviano, L.

    2015-06-01

    Graphene formation on top of SiC(0001) by decoupling the carbon buffer layer through lithium intercalation is investigated. Low-energy electron diffraction and core-level photoemission spectroscopy results show that graphene formation already occurs at room temperature, and that the interface morphology is improved after thermal annealing. Angle-resolved photoemission spectroscopy (ARPES) shows that the resulting graphene layer is strongly n -type doped, and in spite of the decoupling by lithium intercalation, a persistent interaction with the substrate imposes a superperiodicity on the graphene band structure that modulates the π band intensity and gives rise to quasi-(2 ×2 ) π replica bands. Through a comparison of the ARPES-derived band structure with density-functional-theory calculations, we assign the observed bands to SiC-derived states and interface-related ones; this assignment permits us to establish that the intercalated lithium occupies the T4 site on the topmost SiC layer.

  7. Reversible modification of the structural and electronic properties of a boron nitride monolayer by CO intercalation.

    PubMed

    Ng, May Ling; Shavorskiy, Andrey; Rameshan, Christoph; Mikkelsen, Anders; Lundgren, Edvin; Preobrajenski, Alexei; Bluhm, Hendrik

    2015-04-01

    We demonstrate the reversible intercalation of CO between a hexagonal boron nitride (h-BN) monolayer and a Rh(111) substrate above a threshold CO pressure of 0.01 mbar at room temperature. The intercalation of CO results in the flattening of the originally corrugated h-BN nanomesh and an electronic decoupling of the BN layer from the Rh substrate. The intercalated CO molecules assume a coverage and adsorption site distribution comparable to that on the free Rh(111) surface at similar conditions. The pristine h-BN nanomesh is reinstated upon heating to above 625 K. These observations may open up opportunities for a reversible tuning of the electronic and structural properties of monolayer BN films. PMID:25712198

  8. The forces that shape embryos: physical aspects of convergent extension by cell intercalation

    NASA Astrophysics Data System (ADS)

    Keller, Ray; Shook, David; Skoglund, Paul

    2008-03-01

    We discuss the physical aspects of the morphogenic process of convergence (narrowing) and extension (lengthening) of tissues by cell intercalation. These movements, often referred to as 'convergent extension', occur in both epithelial and mesenchymal tissues during embryogenesis and organogenesis of invertebrates and vertebrates, and they play large roles in shaping the body plan during development. Our focus is on the presumptive mesodermal and neural tissues of the Xenopus (frog) embryo, tissues for which some physical measurements have been made. We discuss the physical aspects of how polarized cell motility, oriented along future tissue axes, generate the forces that drive oriented cell intercalation and how this intercalation results in convergence and extension or convergence and thickening of the tissue. Our goal is to identify aspects of these morphogenic movements for further biophysical, molecular and cell biological, and modeling studies.

  9. Porphyrin intercalation in G4-DNA quadruplexes by molecular dynamics simulations.

    PubMed

    Cavallari, Manuela; Garbesi, Anna; Di Felice, Rosa

    2009-10-01

    We investigated the intercalation of a porphyrin derivative (TMPyP) between guanine tetrads (G4-tetrads, G4t's) in 4-stranded G4-DNA oligomers by classical molecular dynamics simulations. Contrary to experimental evidence on very short oligomers that contain stabilizing cations, we find that TMPyP can stack with the G4-tetrads in the absence of interplane cations. A high TMPyP/G4t stoichiometric ratio of 1/2 induces strong deformations of the G4-quadruplexes. A lower ratio of 1/8 is better compatible with the helical conformation. When a TMPyP is accommodated between two tetrads, the stacking distance between the intercalated molecule and a G4-tetrad is approximately 4.3-4.7 A. We find that the possibility of regular TMPyP intercalation depends on the length of the quadruplex, on the stoichiometric ratio and on the edge termination motif. PMID:19754127

  10. H-1 NMR study of ternary ammonia-alkali metal-graphite intercalation compounds

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Fronko, R. M.; Resing, H. A.; Qian, X. W.; Solin, S. A.

    1987-01-01

    For the first-stage ternary ammonia-alkali metal-graphite intercalation compounds M(NH3)(x)C24(x of about 4, M = K, Rb, Cs), three sets of triplet H-1 NMR spectral lines have been observed at various temperatures and orientations due to the H-1 - H-1 and N-14 - H-1 dipolar interactions. The structures of these compounds have been inferred as mobile (liquid-like) intercalant layers of planar M(NH3)4 ions in between the carbon layers. For the intercalated ammonia molecules, the potential barrier is about 0.2 eV and the molecular geometry is very close to the free NH3 in gas phase.

  11. Anion charge storage through oxygen intercalation in LaMnO3 perovskite pseudocapacitor electrodes.

    PubMed

    Mefford, J Tyler; Hardin, William G; Dai, Sheng; Johnston, Keith P; Stevenson, Keith J

    2014-07-01

    Perovskite oxides have attracted significant attention as energy conversion materials for metal-air battery and solid-oxide fuel-cell electrodes owing to their unique physical and electronic properties. Amongst these unique properties is the structural stability of the cation array in perovskites that can accommodate mobile oxygen ions under electrical polarization. Despite oxygen ion mobility and vacancies having been shown to play an important role in catalysis, their role in charge storage has yet to be explored. Herein we investigate the mechanism of oxygen-vacancy-mediated redox pseudocapacitance for a nanostructured lanthanum-based perovskite, LaMnO3. This is the first example of anion-based intercalation pseudocapacitance as well as the first time oxygen intercalation has been exploited for fast energy storage. Whereas previous pseudocapacitor and rechargeable battery charge storage studies have focused on cation intercalation, the anion-based mechanism presented here offers a new paradigm for electrochemical energy storage. PMID:24880729

  12. Anion charge storage through oxygen intercalation in LaMnO3 perovskite pseudocapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Mefford, J. Tyler; Hardin, William G.; Dai, Sheng; Johnston, Keith P.; Stevenson, Keith J.

    2014-07-01

    Perovskite oxides have attracted significant attention as energy conversion materials for metal-air battery and solid-oxide fuel-cell electrodes owing to their unique physical and electronic properties. Amongst these unique properties is the structural stability of the cation array in perovskites that can accommodate mobile oxygen ions under electrical polarization. Despite oxygen ion mobility and vacancies having been shown to play an important role in catalysis, their role in charge storage has yet to be explored. Herein we investigate the mechanism of oxygen-vacancy-mediated redox pseudocapacitance for a nanostructured lanthanum-based perovskite, LaMnO3. This is the first example of anion-based intercalation pseudocapacitance as well as the first time oxygen intercalation has been exploited for fast energy storage. Whereas previous pseudocapacitor and rechargeable battery charge storage studies have focused on cation intercalation, the anion-based mechanism presented here offers a new paradigm for electrochemical energy storage.

  13. In vitro biodegradation and biocompatibility of gelatin/montmorillonite-chitosan intercalated nanocomposite.

    PubMed

    Zhuang, Hong; Zheng, Jun Ping; Gao, Hong; De Yao, Kang

    2007-05-01

    The intercalated nanocomposite of gelatin/montmorillonite-chitosan (Gel/MMT-CS) was prepared via the solution intercalation process. In vitro degradation tests showed that the nanocomposite had a lower degradation rate than Gel-CS composite. And the introduced intercalation structure endowed Gel/MMT-CS nanocomposite with a controllable degradation rate when changing the MMT content. Cells attachment, spread and proliferation on the Gel/MMT-CS membranes were investigated by scanning electron microscopy (SEM) and mitochondrial activity assay. The results provided evidences of good adhesion, proliferation and morphology of rat stromal stem cells on Gel/MMT-CS membranes compared to the tissue culture plates (TCPs), making the Gel/MMT-CS nanocomposite a promising candidate towards tissue engineering. PMID:17221313

  14. An Organometallic Compound which Exhibits a DNA Topology-Dependent One-Stranded Intercalation Mode.

    PubMed

    Ma, Zhujun; Palermo, Giulia; Adhireksan, Zenita; Murray, Benjamin S; von Erlach, Thibaud; Dyson, Paul J; Rothlisberger, Ursula; Davey, Curt A

    2016-06-20

    Understanding how small molecules interact with DNA is essential since it underlies a multitude of pathological conditions and therapeutic interventions. Many different intercalator compounds have been studied because of their activity as mutagens or drugs, but little is known regarding their interaction with nucleosomes, the protein-packaged form of DNA in cells. Here, using crystallographic methods and molecular dynamics simulations, we discovered that adducts formed by [(η(6) -THA)Ru(ethylenediamine)Cl][PF6 ] (THA=5,8,9,10-tetrahydroanthracene; RAED-THA-Cl[PF6 ]) in the nucleosome comprise a novel one-stranded intercalation and DNA distortion mode. Conversely, the THA group in fact remains solvent exposed and does not disrupt base stacking in RAED-THA adducts on B-form DNA. This newly observed DNA binding mode and topology dependence may actually be prevalent and should be considered when studying covalently binding intercalating compounds. PMID:27184539

  15. Myosin II-mediated cell shape changes and cell intercalation contribute to primitive streak formation

    PubMed Central

    Song, Feifei; Sang, Helen M.; Martin, René; Knölker, Hans-Joachim; MacDonald, Michael P; Weijer, Cornelis J

    2016-01-01

    Primitive streak formation in the chick embryo involves large scale highly coordinated flows of over 100.000 cells in the epiblast. These large scale tissue flows and deformations can be correlated with specific anisotropic cell behaviours in the forming mesendoderm through a combined light-sheet microscopy and computational analysis. Relevant behaviours include apical contraction, elongation along the apical-basal axis followed by ingression as well as asynchronous directional cell intercalation of small groups of mesendoderm cells. Cell intercalation is associated with sequential, directional contraction of apical junctions, the onset, localisation and direction of which correlate strongly with the appearance of active Myosin II cables in aligned apical junctions in neighbouring cells. Use of a class specific Myosin inhibitors and gene specific knockdowns show that apical contraction and intercalation are Myosin II dependent and also reveal critical roles for Myosin I and Myosin V family members in the assembly of junctional Myosin II cables. PMID:25812521

  16. Intercalation of diclofenac in modified Zn/Al hydrotalcite-like preparation

    NASA Astrophysics Data System (ADS)

    Heraldy, E.; Suprihatin, R. W.; Pranoto

    2016-02-01

    The intercalation of a pharmaceutically active material diclofenac into modified Zn/Al Hydrotalcite-like (Zn/Al HTlc) preparation has been investigated by the coprecipitation and ion exchange method, respectively. The synthetic materials were characterized using X- Ray Diffraction (XRD); Fourier transforms infrared spectroscopy (FTIR); Scanning Electron Microscope (SEM); X-Ray Fluorescence (XRF) and surface area analyzer. The results show that the basal spacing of the product was expanded to 11.03 A for direct synthesis and 10.68 A for indirect synthesis, suggesting that diclofenac anion was intercalated into Zn/Al HTlc and arranged in a tilted bilayer fashion and the specific surface area of material increased after the intercalation of diclofenac.

  17. Kinetics of reactions in interlayer space of titanium diselenide intercalated with iron

    NASA Astrophysics Data System (ADS)

    Titov, A. N.; Shkvarina, E. G.; Zelenina, L. N.; Chusova, T. P.; Sharafutdinov, M. R.

    2016-04-01

    Decomposition of a homogeneous intercalation compound with the formation of inclusions in the interlayer space of a matrix lattice has been directly observed. In full compliance with previously advanced theoretical concepts, it has been shown that the decomposition is accompanied by metallic iron extraction, which then gradually transforms into iron selenide due to the interaction with gaseous selenium.The hierarchy of diffusion mobilities of various defects in Fe x TiSe2 intercalation compound has been determined. It has been found that the largest mobility is inherent to intrinsic defects of the TiSe2 lattice, i.e., vacancies in Ti and Se sublattices. The phenomenon of dissociation pressure oscillations as a function of time has been detected. This phenomenon has been explained by the existence of a slow decomposition stage, i.e., intercalated iron diffusion during the formation and dissolution of its inclusions as an individual phase.

  18. Force-dependent persistence length of DNA-intercalator complexes measured in single molecule stretching experiments.

    PubMed

    Bazoni, R F; Lima, C H M; Ramos, E B; Rocha, M S

    2015-06-01

    By using optical tweezers with an adjustable trap stiffness, we have performed systematic single molecule stretching experiments with two types of DNA-intercalator complexes, in order to investigate the effects of the maximum applied forces on the mechanical response of such complexes. We have explicitly shown that even in the low-force entropic regime the persistence length of the DNA-intercalator complexes is strongly force-dependent, although such behavior is not exhibited by bare DNA molecules. We discuss the possible physicochemical effects that can lead to such results. In particular, we propose that the stretching force can promote partial denaturation on the highly distorted double-helix of the DNA-intercalator complexes, which interfere strongly in the measured values of the persistence length. PMID:25913936

  19. Electron doping through lithium intercalation to interstitial channels in tetrahedrally bonded SiC

    NASA Astrophysics Data System (ADS)

    Sakai, Yuki; Oshiyama, Atsushi

    2015-11-01

    We report on first-principles calculations that clarify the effect of lithium atom intercalation into zinc blende 3C-silicon carbide (3C-SiC) on electronic and structural properties. Lithium atoms inside 3C-SiC are found to donate electrons to 3C-SiC that is an indication of a new way of electron doping through the intercalation. The electrons doped into the conduction band interact with lithium cations and reduce the band spacing between the original valence and conduction bands. We have also found that a silicon monovacancy in 3C-SiC promotes the lithium intercalation, showing that the vacancy generation makes SiC as a possible anode material for lithium-ion battery.

  20. Unforeseen high temperature and humidity stability of FeCl3 intercalated few layer graphene.

    PubMed

    Wehenkel, Dominique Joseph; Bointon, Thomas Hardisty; Booth, Tim; Bøggild, Peter; Craciun, Monica Felicia; Russo, Saverio

    2015-01-01

    We present the first systematic study of the stability of the structure and electrical properties of FeCl3 intercalated few-layer graphene to high levels of humidity and high temperature. Complementary experimental techniques such as electrical transport, high resolution transmission electron microscopy and Raman spectroscopy conclusively demonstrate the unforseen stability of this transparent conductor to a relative humidity up to 100% at room temperature for 25 days, to a temperature up to 150°C in atmosphere and to a temperature as high as 620°C in vacuum, that is more than twice higher than the temperature at which the intercalation is conducted. The stability of FeCl3 intercalated few-layer graphene together with its unique values of low square resistance and high optical transparency, makes this material an attractive transparent conductor in future flexible electronic applications. PMID:25567796

  1. Unforeseen high temperature and humidity stability of FeCl3 intercalated few layer graphene

    PubMed Central

    Wehenkel, Dominique Joseph; Bointon, Thomas Hardisty; Booth, Tim; Bøggild, Peter; Craciun, Monica Felicia; Russo, Saverio

    2015-01-01

    We present the first systematic study of the stability of the structure and electrical properties of FeCl3 intercalated few-layer graphene to high levels of humidity and high temperature. Complementary experimental techniques such as electrical transport, high resolution transmission electron microscopy and Raman spectroscopy conclusively demonstrate the unforseen stability of this transparent conductor to a relative humidity up to 100% at room temperature for 25 days, to a temperature up to 150°C in atmosphere and to a temperature as high as 620°C in vacuum, that is more than twice higher than the temperature at which the intercalation is conducted. The stability of FeCl3 intercalated few-layer graphene together with its unique values of low square resistance and high optical transparency, makes this material an attractive transparent conductor in future flexible electronic applications. PMID:25567796

  2. NMR studies of the conformation and motion of tetrahydrofuran in graphite intercalation compounds

    SciTech Connect

    Caplan, D. F.

    1991-11-01

    The behavior of tetrahydrofuran (THF) molecules intercalated in graphite layers in compounds Cs(THF){sub 1.3}C{sub 24} and K(THF){sub 2.5}C{sub 24} was studied by proton NMR. The graphite layers in these compounds impose a uniform ordering on the THF molecules, giving rise to sharp NMR spectra. Experimental and simulated proton NMR spectra were used to investigate geometry, orientation and conformation of intercalated THF, and to determine whether pseudorotation, a large amplitude low-frequency vibration observed in gaseous THF, can also occur in the constrained environment provided by the graphite intercalation compounds. Deuterium and multiple quantum proton NMR spectra were also simulated in order to determine if these techniques could further refine the proton NMR results.

  3. Role of Cooperative Interactions in the Intercalation of Heteroatoms between Graphene and a Metal Substrate

    NASA Astrophysics Data System (ADS)

    Du, Shixuan

    Graphene, a two-dimensional crystal of carbon atoms packed in a honeycomb structure, has many promising mechanical, electrical, and optical properties. The intercalation of heteroatoms between graphene and a metal substrate has been studied intensively over the past few years, due to its effect on the graphene properties, and as a method to create vertical heterostructures. Various intercalation processes have been reported with different combinations of heteroatoms and substrates. In this talk, I will present the investigation of the key processes governing the intercalation of heteroatoms between graphene and a substrate by combining atomic-scale characterization with density functional theory (DFT). Si intercalation between graphene and Ru(0001) is chosen as a test bed. We elucidate the role of cooperative interactions between heteroatoms, graphene, and substrate. By combining scanning tunneling microscopy with density functional theory, the intercalation process is confirmed to consist of four key steps, involving creation of defects, migration of heteroatoms, self-repairing of graphene, and growth of an intercalated monolayer. Other combinations of heteroatoms (such as Ni, Pd and Pt) and substrates (such as Ir(111) and SiC(0001)) are also investigated to support the generality of our study. Both theory and experiments indicate that this mechanism applies also to other combinations of heteroatoms and substrates. (G. Li et al., J. Am. Chem. Soc. 137 (2015) 7099. In collaboration with G. Li, H.T. Zhou, L.D. Pan, Y. Zhang, L. Huang, W.Y. Xu, and H.J. Gao in CAS, Min Ouyang in MU, and A.C. Ferrari in U. Cambridge.)

  4. Combined experimental and theoretical investigation of interactions between kaolinite inner surface and intercalated dimethyl sulfoxide

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Liu, Qinfu; Cheng, Hongfei; Zeng, Fangui

    2015-03-01

    Kaolinite intercalation complex with dimethyl sulfoxide (DMSO) was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry-differential scanning calorimetry (TG-DSC) combined with molecular dynamics simulation. The bands assigned to the OH stretching of inner surface of kaolinite were significantly perturbed after intercalation of DMSO into kaolinite. Additionally, the bands attributed to the vibration of gibbsite-like layers of kaolinite shifted to the lower wave number, indicating that the intercalated DMSO were strongly hydrogen bonded to the alumina octahedral surface of kaolinite. The slightly decreased intensity of 1031 cm-1 and 1016 cm-1 band due to the in-plane vibration of Sisbnd O of kaolinite revealed that some DMSO molecules formed weak hydrogen bonds with the silicon tetrahedral surface of kaolinite. Based on the TG result of kaolinite-DMSO intercalation complex, the formula of A12Si2O5(OH)4(DMSO)0.7 was obtained, with which the kaolinite-DMSO complex model was constructed. The molecular dynamics simulation of kaolinite-DMSO complex directly confirmed the monolayer structure of DMSO in interlayer space of kaolinite, where the DMSO arranged almost parallel with kaolinite basal surface with all methyl groups being distributed near the interlayer midplane and oxygen atoms orienting toward to the alumina octahedral surface. The radial distribution function between kaolinite and intercalated DMSO verified the strong hydrogen bonds forming between hydroxyl hydrogen atoms of alumina octahedral surface and oxygen atoms of DMSO. Moreover, some methyl groups of DMSO were weakly hydrogen bonded to the oxygen atoms of silicon tetrahedral surface through the hydrogen atoms. The mean square displacement of DMSO oxygen atoms and hydrogen atoms in z direction kept unchanged during the simulation time because of the hydrogen-bond interaction between inner surface of kaolinite and DMSO, which constrained the mobility

  5. Intercalation behavior of poly(ethylene glycol) in organically modified montmorillonite

    NASA Astrophysics Data System (ADS)

    Zhu, Shipeng; Peng, Hongmei; Chen, Jinyao; Li, Huilin; Cao, Ya; Yang, Yunhua; Feng, Zhihai

    2013-07-01

    In this paper, two kinds of organically modified montmorillonite (OMMT) were prepared using alkylammonium surfactants with different alkyl chain numbers. XRD results showed the interlayer spacing of OMMT increased with low concentration surfactants. With further increasing the surfactants concentration, the interlayer spacing of OMMT was unchanged. Meanwhile, FTIR was used to characterize the local environments of surfactants in the interlayer space of OMMT. The results suggested that the double chain surfactant D-18 preferred to adopt highly ordered conformation compared with single chain surfactant S-18 in interlayer space of OMMT. It indicated that the surface property of the OMMT is affected by the concentration and configuration of the intercalated surfactants. Moreover, the effect of the OMMT type, or more particularly the chemical nature of the organic modifier in the interlayer spacing and the poly(ethylene glycol) (PEG) concentration onintercalation behavior of PEG chains in OMMT were investigated with XRD and DSC.The results indicated that PEG chains could not intercalate into Na-MMT when the surfactants were saturated in interlayer space of Na-MMT. PEG chains could intercalate into the interlayer space of SM when the S-18 concentration was lower than 2.00CEC, implying that the low surfactant concentration modified SM provided a better environment (presumably through the balanced hydrophobic and hydrophilic surfaces) for the PEG intercalation as well. However, PEG did not intercalate into the interlayer space of DM when the D-18 concentration was higher than 1.00CEC. It could be attributed to the hydrophobic double alkyl chains of DM increased with D-18. The increased hydrophobic properties in the interlayer space of 1.50DM hybrids can prevent the intercalation of hydrophilic PEG.

  6. Preparation and release behavior of chlorpyrifos adsolubilized into layered zinc hydroxide nitrate intercalated with dodecylbenzenesulfonate.

    PubMed

    Liu, Jiexiang; Zhang, Xiaoguang; Zhang, Yongqing

    2015-06-01

    A novel method was developed to make the charge-neutral and poorly water-soluble pesticide chlorpyrifos (CPF) adsolubilize into layered zinc hydroxide nitrate intercalated with dodecylbenzenesulfonate (ZHN-DBS). It included two steps: first, CPF was solubilized into the micelles formed by anionic surfactant sodium dodecylbenzenesulfonate (DBS), nonionic surfactant polyoxyethylene (10) nonyl phenyl ether (TX-10) or zwitterionic surfactant dodecyl betaine (DB), and then ZHN-DBS was poured into CPF micelles to synthesize ZHN-DBS-CPF, ZHN-TX-10-CPF, and ZHN-DB-CPF intercalated compounds. These intercalated compounds were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis and differential thermal analysis (TGA/DTA). The results showed that ZHN-DBS-CPF, ZHN-TX-10-CPF, and ZHN-DB-CPF had the basal spacings of 3.29-3.59, 2.57-2.87, and 1.97 nm, respectively, which was discussed from the intercalated mechanism. The intercalated CPF had the higher thermal stability. Release behaviors of CPF from intercalated compounds were investigated and analyzed in buffer solutions (pH 5.0 and 6.8). The results exhibited that the release rates and equilibrium release amounts of CPF were closely dependent on micelles types and release mediums. The release behaviors of ZHN-DBS-CPF and ZHN-TX-10-CPF were well described with pseudo second-order and parabolic diffusion models. The present study suggested that ZHN-DBS-CPF and ZHN-TX-10-CPF could be applied as a potential pesticide delivery system. PMID:25970564

  7. Hydroxy double salts loaded with bioactive ions: Synthesis, intercalation mechanisms, and functional performance

    NASA Astrophysics Data System (ADS)

    Kaassis, Abdessamad Y. A.; Xu, Si-Min; Guan, Shanyue; Evans, David G.; Wei, Min; Williams, Gareth R.

    2016-06-01

    The intercalation of the anions of diclofenac (Dic), naproxen (Nap), and valproic acid (Val) into three hydroxy double salts (HDSs) has been explored in this work. Experiments were performed with [Co1.2Zn3.8(OH)8](NO3)2·2H2O (CoZn-NO3), [Ni2Zn3(OH)8](NO3)2·2H2O (NiZn-NO3) and [Zn5(OH)8](NO3)2·2H2O (Zn-NO3). It proved possible to intercalate diclofenac and naproxen into all three HDSs. In contrast, Val could be intercalated into CoZn-NO3 but when it was reacted with Zn-NO3 the HDS structure was destroyed, and the product comprised ZnO. Successful intercalation was verified by X-ray diffraction, IR spectroscopy, and elemental microanalysis. Molecular dynamics simulations showed the Dic and Nap ions to arrange themselves in an "X" shape in the interlayer space, forming a bilayer. Val was found to adopt a position with its aliphatic groups parallel to the HDS layer, again in a bilayer. In situ time resolved X-ray diffraction experiments revealed that intercalation of Dic and Nap into CoZn-NO3 and Zn-NO3 is mechanistically complex, with a number of intermediate phases observed. In contrast, the intercalation of all three guests into NiZn-NO3 and of Val into CoZn-NO3 are simple one step reactions proceeding directly from the starting material to the product. The HDS-drug composites were found to have sustained release profiles.

  8. Interoperability and information discovery

    USGS Publications Warehouse

    Christian, E.

    2001-01-01

    In the context of information systems, there is interoperability when the distinctions between separate information systems are not a barrier to accomplishing a task that spans those systems. Interoperability so defined implies that there are commonalities among the systems involved and that one can exploit such commonalities to achieve interoperability. The challenge of a particular interoperability task is to identify relevant commonalities among the systems involved and to devise mechanisms that exploit those commonalities. The present paper focuses on the particular interoperability task of information discovery. The Global Information Locator Service (GILS) is described as a policy, standards, and technology framework for addressing interoperable information discovery on a global and long-term basis. While there are many mechanisms for people to discover and use all manner of data and information resources, GILS initiatives exploit certain key commonalities that seem to be sufficient to realize useful information discovery interoperability at a global, long-term scale. This paper describes ten of the specific commonalities that are key to GILS initiatives. It presents some of the practical implications for organizations in various roles: content provider, system engineer, intermediary, and searcher. The paper also provides examples of interoperable information discovery as deployed using GILS in four types of information communities: bibliographic, geographic, environmental, and government.

  9. The Discovery of America

    ERIC Educational Resources Information Center

    Martin, Paul S.

    1973-01-01

    Discusses a model for explaining the spread of human population explosion on North American continent since its discovery 12,000 years ago. The model may help to map the spread of Homo sapiens throughout the New World by using the extinction chronology of the Pleistocene megafauna. (Author/PS)

  10. The Discovery Way

    ERIC Educational Resources Information Center

    Hamlin, Theresa

    2005-01-01

    At the Center for Discovery (The Center), a private, non-profit agency 80 miles northwest of New York City in the Catskill Mountains, children are growing and learning at their own pace, in their own way, with careful attention focused on communication and social/emotional development. Children with autism are being educated to be social beings,…

  11. Birds. Nature Discovery I.

    ERIC Educational Resources Information Center

    Stone, Sally F.

    The birds of New England and their particular habitats are explored in this guide which is part of a series of Nature Discovery publications. The materials are designed to directly supplement the natural science curricula and to complement other subject areas including social studies, language arts, music, and art. The program is designed for…

  12. STS-85 Discovery Launch

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Blasting through the hazy late morning sky, the Space Shuttle Discovery soars from Launch Pad 39A at 10:41 a.m. EDT Aug. 7 on the 11-day STS-85 mission. Aboard Discovery are Commander Curtis L. Brown, Jr.; Pilot Kent V. Rominger, Payload Commander N. Jan Davis, Mission Specialist Robert L. Curbeam, Jr., Mission Specialist Stephen K. Robinson and Payload Specialist Bjarni V. Tryggvason, a Canadian Space Agency astronaut . The primary payload aboard the Space Shuttle orbiter Discovery is the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite-2 (CRISTA-SPAS-2) free-flyer. The CRISTA-SPAS-2 will be deployed on flight day 1 to study trace gases in the Earths atmosphere as a part of NASAs Mission to Planet Earth program. Also aboard the free-flying research platform will be the Middle Atmosphere High Resolution Spectrograph Instrument (MAHRSI). Other payloads on the 11-day mission include the Manipulator Flight Demonstration (MFD), a Japanese Space Agency-sponsored experiment. Also in Discoverys payload bay are the Technology Applications and Science-1 (TAS-1) and International Extreme Ultraviolet Hitchhiker-2 (IEH-2) experiments.

  13. Scientific Discovery for All

    ERIC Educational Resources Information Center

    Zaikowski, Lori; Lichtman, Paul; Quarless, Duncan

    2007-01-01

    The scientific discovery process comes alive for 70 minority students each year at Uniondale High School in New York where students have won top awards for "in-house" projects. Uniondale High School is in a middle-income school district where over 95% of students are from minority groups. Founded in 2000, the Uniondale High School Research Program…

  14. Historian's Discovery of Childhood

    ERIC Educational Resources Information Center

    Frijhoff, Willem

    2012-01-01

    The "discovery of childhood" is a tricky notion because childhood is as much a fact of a biological and psychological nature as a cultural notion that through the centuries has been the object of changing perceptions, definitions, and images. Children barely speak in history; virtually everything we know about them is mediated by adults. Then how…

  15. Knowledge Discovery in Databases.

    ERIC Educational Resources Information Center

    Norton, M. Jay

    1999-01-01

    Knowledge discovery in databases (KDD) revolves around the investigation and creation of knowledge, processes, algorithms, and mechanisms for retrieving knowledge from data collections. The article is an introductory overview of KDD. The rationale and environment of its development and applications are discussed. Issues related to database design…

  16. Atomic stereophotograph of intercalation compound Fe{sub 1/3}NbS{sub 2}

    SciTech Connect

    Guo, F.Z.; Matsushita, T.; Kobayashi, K.; Matsui, F.; Kato, Y.; Daimon, H.; Koyano, M.; Yamamura, Y.; Tsuji, T.; Saitoh, Y.

    2006-01-15

    Stereoatomscope was used to study the atomic arrangements of intercalation compound Fe{sub 1/3}NbS{sub 2}. The three-dimensional atomic arrangements around different kinds of atoms (Nb and Fe) are visualized by taking the photoelectron angular distribution (PEAD) patterns at clockwise and counterclockwise circularly polarized lights. Atomic distances between the emitters and the scatterers are obtained from the PEAD patterns by measuring the rotation angles of the forward focusing peaks. The applications of stereoatomscope to intercalation compound show the possibility to build an ultimate microscope for scientist.

  17. Plasma synthesis of lithium based intercalation powders for solid polymer electrolyte batteries

    SciTech Connect

    Kong, Peter C.; Pink, Robert J.; Nelson, Lee O.

    2005-01-04

    The invention relates to a process for preparing lithium intercalation compounds by plasma reaction comprising the steps of: forming a feed solution by mixing lithium nitrate or lithium hydroxide or lithium oxide and the required metal nitrate or metal hydroxide or metal oxide and between 10-50% alcohol by weight; mixing the feed solution with O.sub.2 gas wherein the O.sub.2 gas atomizes the feed solution into fine reactant droplets, inserting the atomized feed solution into a plasma reactor to form an intercalation powder; and if desired, heating the resulting powder to from a very pure single phase product.

  18. Mg2Si As Li-Intercalation Host For Li Cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo; Surampudi, Subbarao; Attia, Alan; Halpert, Gerald

    1993-01-01

    Compound Mg2Si shows promise as lithium-intercalation host for ambient-temperature rechargeable lithium electrochemical cells. As anode reactant material, LiXMg2Si chemically stable in presence of organic electrolyte used in such cells and stores large amounts of lithium. Intercalation reactions highly reversible at room temperature. Also retains sufficient mechanical strength during charge/discharge cycling. Lithium cells containing LixMg2Si anodes prove useful in spacecraft, military, communications, automotive, and other applications in which high energy-storage densities of lithium cells in general and rechargeability of cells needed.

  19. Intercalation-induced phases in layer compounds of the A /SUP III/ B /SUP VI/ -type

    SciTech Connect

    Kovalyuk, Z.D.; Pyrlya, M.N.; Seredyuk, A.I.; Tovstyuk, K.D.

    1986-03-01

    The authors investigate the kinetics of combined electrochemical intercalation and the physicochemical properties of the introduced phases. InSe and GaSe single crystals were used in the experiments; the crystals were grown by the Bridgman method. The authors determined the concentration dependences of the electrode potentials and electrical conductivity of the compounds InSe and GaSe intercalated with lithium and lead. The results of the measurements are presented. Lithium and lead enter into the matrix of the crystals in a nonconducting state.

  20. Effect of Ni, Fe intercalation on the superconducting properties of ZrTe3

    NASA Astrophysics Data System (ADS)

    Yadav, C. S.; Paulose, P. L.

    2012-06-01

    We report the superconductivity at enhanced temperature of 5.2 K in the polycrystalline sample of ZrTe3 and Ni intercalated ZrTe3. ZrTe3 is a Charge Density Wave (T = 63K) compound, which is known to superconduct only below 2K in single crystalline form. We discuss that the intergrain strains in the polycrystalline samples induces an intrinsic pressure and thus enhances the transition temperature. Fe intercalation of ZrTe3 kills both the charge density wave and superconducting states, gives rise to the magnetic ordering in the compound.

  1. Spectroscopic studies on Rhodamine B intercalated K-10 montmorillonite aqueous dispersions

    NASA Astrophysics Data System (ADS)

    Joseph, Lyjo K.; Suja, H.; Sanjay, G.; Sugunan, S.; Nampoori, V. P. N.; Radhakrishnan, P.

    2015-02-01

    In this paper, the optical absorption and fluorescence studies on rhodamine B (RB) intercalated acid activated K-10 montmorillonite dispersions is presented. The aqueous dispersions were prepared from the dried dye intercalated montmorillonite. The absorption and fluorescence peaks of RB dispersions show a bathochromic shift with respect to the dye concentrations. The samples have a fluorescent emission at 421 nm which is having an intensity variation depending on the concentration of the dyes. The behaviour of samples of same concentration prepared by two different routes is also presented.

  2. The effect of hydrazine intercalation on the structure and capacitance of 2D titanium carbide (MXene)

    DOE PAGESBeta

    Mashtalir, O.; Lukatskaya, Maria R.; Kolesnikov, Alexander I.; Raymundo-Pinero, E.; Naguib, Michael; Barsoum, M. W.; Gogotsi, Yury G.

    2016-03-25

    Herein we show that hydrazine intercalation into 2D titanium carbide (Ti3C2-based MXene) results in changes in its surface chemistry by decreasing the amounts of fluorine, OH surface groups and intercalated water. It also creates a pillaring effect between Ti3C2Tx layers pre-opening the structure and improving the accessability to active sites. Furthermore, the hydrazine treated material has demonstrated a greatly improved capacitance of 250 F g–1 in acidic electrolytes with an excellent cycling ability for electrodes as thick as 75 μm.

  3. Plasma Synthesis of Lithium Based Intercalation Powders for Solid Polymer Electrolyte Batteries

    SciTech Connect

    Kong, Peter C.; Pink, Robert J.; Nelson, Lee O.

    2005-01-04

    The invention relates to a process for preparing lithium intercalation compounds by plasma reaction comprising the steps of: forming a feed solution by mixing lithium nitrate or lithium hydroxide or lithium oxide and the required metal nitrate or metal hydroxide or metal oxide and between 10-50% alcohol by weight; mixing the feed solution with O2 gas wherein the O2 gas atomizes the feed solution into fine reactant droplets, inserting the atomized feed solution into a plasma reactor to form an intercalation powder; and if desired, heating the resulting powder to form a very pure single phase product.

  4. Synthesis, DNA-binding and biological activity of a double intercalating analog of ethidium bromide.

    PubMed Central

    Kuhlmann, K F; Charbeneau, N J; Mosher, C W

    1978-01-01

    A bis-phenanthridinium salt has been synthesized and its DNA-binding studied. Evidence provided by UV and CD spectra, by thermal denaturation profiles and by equilibrium dialysis of the drug-DNA complex lead to the conclusion that both phenanthridine moieties intercalate in the helix. The double intercalator appears to be less potent than ethidium chloride as an inhibitor of nucleic acid synthesis in cultured L1210 cells, though it is more potent than a monomeric analog. The low potency may be due to a low cell influx rate. PMID:673863

  5. Isolation of high quality graphene from Ru by solution phase intercalation

    NASA Astrophysics Data System (ADS)

    Koren, E.; Sutter, E.; Bliznakov, S.; Ivars-Barcelo, F.; Sutter, P.

    2013-09-01

    We introduce a method for isolating graphene grown on epitaxial Ru(0001)/α-Al2O3. The strong graphene/Ru(0001) coupling is weakened by electrochemically driven intercalation of hydrogen underpotentially deposited in aqueous KOH solution, which allows the penetration of water molecules at the graphene/Ru(0001) interface. Following these electrochemically driven processes, the graphene can be isolated by electrochemical hydrogen evolution and transferred to arbitrary supports. Raman and transport measurements demonstrate the high quality of the transferred graphene. Our results show that intercalation, typically carried out in vacuum, can be extended to solution environments for graphene processing under ambient conditions.

  6. Internal pressure in superconducting Cu-intercalated Bi2Se3

    NASA Astrophysics Data System (ADS)

    Ribak, Amit; Chashka, Khanan B.; Lahoud, Elias; Naamneh, Muntaser; Rinott, Shahar; Ein-Eli, Yair; Plumb, Nicholas C.; Shi, Ming; Rienks, Emile; Kanigel, Amit

    2016-02-01

    Angle-resolved photoemission spectroscopy is used to study the band structure of superconducting electrochemically intercalated CuxBi2Se3 . We find that in these samples, the band gap at the Γ point is much larger than in pristine Bi2Se3 . Comparison to the results of band structure calculations indicates that the origin of this large gap is internal stress caused by disorder created by the Cu intercalation. We suggest that the internal pressure may be necessary for superconductivity in CuxBi2Se3 .

  7. Intercalated carbon nanotubes as a template for the preparation of supported heteroatomic nanoparticles.

    PubMed

    Schouler, Marie-Claude; Chamssedine, Fadel; Claves, Daniel

    2011-03-01

    Chemistry in confined conditions is explored at the level of the interlayer space of multiwall carbon nanotubes. Starting from preliminary intercalated tubes, a ligand exchange reaction has been successfully conducted within the former Van der Waals gap, resulting in a final dispersion of heteroatomic particles, around 2 nm large and nearly homogeneous in size, on the outer surface of the tubes. Intercalated tubular carbon architectures thus prove to be interesting templates for a bottom-up preparation of chemically complex supported nanoparticles, with potential activities for versatile applications. PMID:21449382

  8. The effect of hydrazine intercalation on the structure and capacitance of 2D titanium carbide (MXene).

    PubMed

    Mashtalir, O; Lukatskaya, M R; Kolesnikov, A I; Raymundo-Piñero, E; Naguib, M; Barsoum, M W; Gogotsi, Y

    2016-04-28

    Herein we show that hydrazine intercalation into 2D titanium carbide (Ti3C2-based MXene) results in changes in its surface chemistry by decreasing the amounts of fluorine, OH surface groups and intercalated water. It also creates a pillaring effect between Ti3C2Tx layers pre-opening the structure and improving the accessability to active sites. The hydrazine treated material has demonstrated a greatly improved capacitance of 250 F g(-1) in acidic electrolytes with an excellent cycling ability for electrodes as thick as 75 μm. PMID:27088300

  9. Reversible de-intercalation and intercalation induced by polymer crystallization and melting in a poly(ethylene oxide)/organoclay nanocomposite.

    PubMed

    Sun, Lu; Ertel, Ethan A; Zhu, Lei; Hsiao, Benjamin S; Avila-Orta, Carlos A; Sics, Igors

    2005-06-21

    Semicrystalline polymer/layered silicate nanocomposites were prepared by solution blending of a low molecular weight poly(ethylene oxide) (PEO) with an organically modified montmorillonite, Cloisite 10A (C10A). The intercalation morphology was studied by temperature-dependent synchrotron wide-angle X-ray diffraction (WAXD). Unlike PEO homopolymers, significant secondary crystallization was observed in the PEO/C10A nanocomposites. Reversible de-intercalation and intercalation processes were detected during secondary crystallization and subsequent melting of secondary crystals. On the basis of two-dimensional WAXD results on oriented samples, an interphase layer between the silicate primary particles and PEO lamellar crystals was proposed. Secondary PEO crystallization in the interphase regions was inferred to be the primary driving force for polymer chains to diffuse out of the silicate gallery. This study provided a useful method to investigate polymer diffusion in nanoconfined spaces, which can be controlled by PEO secondary crystallization and melting outside the silicate gallery. PMID:15952806

  10. COPD Discovery Might Improve Treatment

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_158852.html COPD Discovery Might Improve Treatment Study may help pinpoint ... will progress, a discovery they believe could improve COPD treatment. Their research might help doctors determine which ...

  11. Fermi Surface of Donor and Acceptor Graphite Intercalation Compounds.

    NASA Astrophysics Data System (ADS)

    Wang, Guonan

    The Fermi surfaces and the electronic properties of the donor-type stage-1 C_8K and stage-2 C_{24}K, as well as the acceptor-type stage-2 BiCl_3, stage-3 HgCl_2 and stage-3 SbF _5 graphite intercalation compounds were investigated by means of the de Haas-van Alphen effect. The dHvA spectra of the stage-1 C_8 K exhibit two dHvA frequencies, 3126 T and 4250 T. The corresponding effective masses were 0.86 m _0 and 0.92 m_0, respectively. The angular dependence of the dHvA frequencies for a direction within +/-18^circ of the c-axis showed that there are both three-dimensional and two dimensional parts of the Fermi surfaces in C _8K. The three-dimensional Fermi surface has a cross-sectional area corresponding to the dHvA frequency of 3126 T. The charge transfer per potassium atom measured from the dHvA effect is 0.97. This implies that the potassium is ionized completely. These dHvA experimental results support both the Tatar and Rabii model and the revised Ohno, Nakao and Kamimura model for C_8K. Two dominant dHvA frequencies were obtained in stage-2 C_{24}K. They are 286 T and 2570 T, respectively. The predictions of Blinowski's model are in agreement with the experimental data. The charge transfer per potassium is found to be 0.88. This suggests that the potassium s-band is above the Fermi level in C_{24}K. The dHvA measurements for the acceptor compounds show that the stage-2 BiCl_3 GIC had two dHvA frequencies, 327T and 1012T, and each stage -3 compound had three dominant frequencies. They are 121T, 523T and 664T for HgCl_2, and 172T, 656T and 852T for SbF_5. The cyclotron masses corresponding to the dHvA frequencies for these compounds were measured from the temperature dependence of the dHvA amplitudes. The theoretical predictions of the dHvA frequencies and the cyclotron masses from the Blinowski's band models for stage-2 and stage-3 compounds are in agreement with the experimental results. The angular dependence of the dHvA frequencies show that the Fermi

  12. The Discovery Method in Training.

    ERIC Educational Resources Information Center

    Belbin, R. M.

    In the form of a discussion between faceless people, this booklet concerns discovery learning and its advantages. Subjects covered in the discussions are: Introducing the Discovery Method; An Experiment with British Railways; The OECD Research Projects in U.S.A., Austria, and Sweden; How the Discovery Method Differs from Other Methods; Discovery…

  13. Recent Discoveries and Bible Translation.

    ERIC Educational Resources Information Center

    Harrelson, Walter

    1990-01-01

    Discusses recent discoveries for "Bible" translation with a focus on the "Dead Sea Scrolls." Examines recent discoveries that provide direct support for alternative reading of biblical passages and those discoveries that have contributed additional insight to knowledge of cultural practices, especially legal and religious practices. (DB)

  14. Discovery of Isotopes

    NASA Astrophysics Data System (ADS)

    May, Erin; Thoennessen, Michael

    2011-10-01

    To date, no comprehensive study has been undertaken regarding the initial detection and identification of isotopes. At NSCL, a project has been initiated to catalog and report the initial observation of every isotope. The conditions characterizing the successful discovery of an isotope include a clear and unambiguous mass and element identification through decay curves, mass spectroscopy, gamma-ray spectra, and/or relationships to other isotopes, as well as the publication of such findings in a refereed journal. I will present the documentation for eight elements: cesium, lanthanum, praseodymium, promethium, samarium, europium, gadolinium, and terbium. The year and author of each initial publication along with the location and methods of production and identification will be shown. A summary and overview of all ~3000 isotopes documented so far as a function of discovery year, method and place will also be presented.

  15. Challenges of Antibacterial Discovery

    PubMed Central

    Silver, Lynn L.

    2011-01-01

    Summary: The discovery of novel small-molecule antibacterial drugs has been stalled for many years. The purpose of this review is to underscore and illustrate those scientific problems unique to the discovery and optimization of novel antibacterial agents that have adversely affected the output of the effort. The major challenges fall into two areas: (i) proper target selection, particularly the necessity of pursuing molecular targets that are not prone to rapid resistance development, and (ii) improvement of chemical libraries to overcome limitations of diversity, especially that which is necessary to overcome barriers to bacterial entry and proclivity to be effluxed, especially in Gram-negative organisms. Failure to address these problems has led to a great deal of misdirected effort. PMID:21233508

  16. Recommendation Knowledge Discovery

    NASA Astrophysics Data System (ADS)

    McSherry, David; Stretch, Christopher

    Recently we presented a novel approach to the discovery of recommendation rules from a product case base that take account of all features of a recommended product, including those with respect to which the user's preferences are unknown. In this paper, we investigate the potential role of default preferences in the discovery of recommendation rules. As we show in the domain of digital cameras, the potential benefits include a dramatic reduction in the effective length of the discovered rules and increased coverage of queries representing the user's personal preferences. Another important finding of the research presented is that in a recommender system that takes account of default preferences, many of the products in the case base may never be recommended.

  17. Discoveries in Photosynthesis

    NASA Astrophysics Data System (ADS)

    Govindjee; Beatty, J. T.; Gest, H.; Allen, J. F.

    "Life Is Bottled Sunshine" [Wynwood Reade, Martyrdom of Man, 1924]. This inspired phrase is a four-word summary of the significance of photosynthesis for life on earth. The study of photosynthesis has attracted the attention of a legion of biologists, biochemists, chemists and physicists for over 200 years. Discoveries in Photosynthesis presents a sweeping overview of the history of photosynthesis investigations, and detailed accounts of research progress in all aspects of the most complex bioenergetic process in living organisms.

  18. Discovery as a process

    SciTech Connect

    Loehle, C.

    1994-05-01

    The three great myths, which form a sort of triumvirate of misunderstanding, are the Eureka! myth, the hypothesis myth, and the measurement myth. These myths are prevalent among scientists as well as among observers of science. The Eureka! myth asserts that discovery occurs as a flash of insight, and as such is not subject to investigation. This leads to the perception that discovery or deriving a hypothesis is a moment or event rather than a process. Events are singular and not subject to description. The hypothesis myth asserts that proper science is motivated by testing hypotheses, and that if something is not experimentally testable then it is not scientific. This myth leads to absurd posturing by some workers conducting empirical descriptive studies, who dress up their study with a ``hypothesis`` to obtain funding or get it published. Methods papers are often rejected because they do not address a specific scientific problem. The fact is that many of the great breakthroughs in silence involve methods and not hypotheses or arise from largely descriptive studies. Those captured by this myth also try to block funding for those developing methods. The third myth is the measurement myth, which holds that determining what to measure is straightforward, so one doesn`t need a lot of introspection to do science. As one ecologist put it to me ``Don`t give me any of that philosophy junk, just let me out in the field. I know what to measure.`` These myths lead to difficulties for scientists who must face peer review to obtain funding and to get published. These myths also inhibit the study of science as a process. Finally, these myths inhibit creativity and suppress innovation. In this paper I first explore these myths in more detail and then propose a new model of discovery that opens the supposedly miraculous process of discovery to doser scrutiny.

  19. Discovery management workshop

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Two dozen participants assembled under the direction of the NASA Solar System Exploration Division (SEED) April 13-15, 1993. Participants supported the goals of cheaper and faster solar system exploration. The workshop concluded that the Discovery Program concept and goals are viable. Management concerns are articulated in the final report. Appendix A includes lists of participants in alphabetical order, by functional area, and by organization type. Appendix B includes the agenda for the meeting.

  20. Discovery with FAST

    NASA Astrophysics Data System (ADS)

    Wilkinson, P.

    2016-02-01

    FAST offers "transformational" performance well-suited to finding new phenomena - one of which might be polarised spectral transients. But discoveries will only be made if "the system" provides its users with the necessary opportunities. In addition to designing in as much observational flexibility as possible, FAST should be operated with a philosophy which maximises its "human bandwidth". This band includes the astronomers of tomorrow - many of whom not have yet started school or even been born.

  1. Discovery concepts for Mars

    NASA Technical Reports Server (NTRS)

    Luhmann, J. G.; Russell, C. T.; Brace, L. H.; Nagy, A. F.; Jakosky, B. M.; Barth, C. A.; Waite, J. H.

    1992-01-01

    Two focused Mars missions that would fit within the guidelines for the proposed Discovery line are discussed. The first mission would deal with the issue of the escape of the atmosphere (Mars') to space. A complete understanding of this topic is crucial to deciphering the evolution of the atmosphere, climate change, and volatile inventories. The second mission concerns the investigation of remanent magnetization of the crust and its relationship to the ionosphere and the atmosphere.

  2. The language of discovery.

    PubMed

    Souba, Wiley

    2011-01-01

    Discovery, as a public attribution, and discovering, the act of conducting research, are experiences that entail "languaging" the unknown. This distinguishing property of language - its ability to bring forth, out of the unspoken realm, new knowledge, original ideas, and novel thinking - is essential to the discovery process. In sharing their ideas and views, scientists create co-negotiated linguistic distinctions that prompt the revision of established mental maps and the adoption of new ones. While scientific mastery entails command of the conversational domain unique to a specific discipline, there is an emerging conversational domain that must be mastered that goes beyond the language unique to any particular specialty. Mastery of this new conversational domain gives researchers access to their hidden mental maps that limit their ways of thinking about and doing science. The most effective scientists use language to recontextualize their approach to problem-solving, which triggers new insights (previously unavailable) that result in new discoveries. While language is not a replacement for intuition and other means of knowing, when we try to understand what's outside of language we have to use language to do so. PMID:21688238

  3. The language of discovery

    PubMed Central

    Souba, Wiley

    2011-01-01

    Discovery, as a public attribution, and discovering, the act of conducting research, are experiences that entail “languaging” the unknown. This distinguishing property of language ‐ its ability to bring forth, out of the unspoken realm, new knowledge, original ideas, and novel thinking – is essential to the discovery process. In sharing their ideas and views, scientists create co‐negotiated linguistic distinctions that prompt the revision of established mental maps and the adoption of new ones. While scientific mastery entails command of the conversational domain unique to a specific discipline, there is an emerging conversational domain that must be mastered that goes beyond the language unique to any particular specialty. Mastery of this new conversational domain gives researchers access to their hidden mental maps that limit their ways of thinking about and doing science. The most effective scientists use language to recontextualize their approach to problem‐solving, which triggers new insights (previously unavailable) that result in new discoveries. While language is not a replacement for intuition and other means of knowing, when we try to understand what’s outside of language we have to use language to do so. PMID:21688238

  4. Temperature dependent local atomic displacements in ammonia intercalated iron selenide superconductor.

    PubMed

    Paris, E; Simonelli, L; Wakita, T; Marini, C; Lee, J-H; Olszewski, W; Terashima, K; Kakuto, T; Nishimoto, N; Kimura, T; Kudo, K; Kambe, T; Nohara, M; Yokoya, T; Saini, N L

    2016-01-01

    Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Lix(NH3)yFe2Se2 superconductor with Tc ~ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across Tc, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity. PMID:27276997

  5. Intercalation and controlled release of pharmaceutically active compounds from a layered double hydroxide.

    PubMed

    Khan, A I; Lei, L; Norquist, A J; O'Hare, D

    2001-11-21

    A series of pharmaceutically active compounds including diclofenac, gemfibrozil, ibuprofen, naproxen, 2-propylpentanoic acid, 4-biphenylacetic acid and tolfenamic acid can be reversibly intercalated into a layered double hydroxide, initial studies suggest that these materials may have application as the basis of a novel tuneable drug delivery system. PMID:12240066

  6. Renal intercalated cells are rather energized by a proton than a sodium pump

    PubMed Central

    Chambrey, Régine; Kurth, Ingo; Peti-Peterdi, Janos; Houillier, Pascal; Purkerson, Jeffrey M.; Leviel, Françoise; Hentschke, Moritz; Zdebik, Anselm A.; Schwartz, George J.; Hübner, Christian A.; Eladari, Dominique

    2013-01-01

    The Na+ concentration of the intracellular milieu is very low compared with the extracellular medium. Transport of Na+ along this gradient is used to fuel secondary transport of many solutes, and thus plays a major role for most cell functions including the control of cell volume and resting membrane potential. Because of a continuous leak, Na+ has to be permanently removed from the intracellular milieu, a process that is thought to be exclusively mediated by the Na+/K+-ATPase in animal cells. Here, we show that intercalated cells of the mouse kidney are an exception to this general rule. By an approach combining two-photon imaging of isolated renal tubules, physiological studies, and genetically engineered animals, we demonstrate that inhibition of the H+ vacuolar-type ATPase (V-ATPase) caused drastic cell swelling and depolarization, and also inhibited the NaCl absorption pathway that we recently discovered in intercalated cells. In contrast, pharmacological blockade of the Na+/K+-ATPase had no effects. Basolateral NaCl exit from β-intercalated cells was independent of the Na+/K+-ATPase but critically relied on the presence of the basolateral ion transporter anion exchanger 4. We conclude that not all animal cells critically rely on the sodium pump as the unique bioenergizer, but can be replaced by the H+ V-ATPase in renal intercalated cells. This concept is likely to apply to other animal cell types characterized by plasma membrane expression of the H+ V-ATPase. PMID:23610411

  7. The effect of hydrazine intercalation on the structure and capacitance of 2D titanium carbide (MXene)

    NASA Astrophysics Data System (ADS)

    Mashtalir, O.; Lukatskaya, M. R.; Kolesnikov, A. I.; Raymundo-Piñero, E.; Naguib, M.; Barsoum, M. W.; Gogotsi, Y.

    2016-04-01

    Herein we show that hydrazine intercalation into 2D titanium carbide (Ti3C2-based MXene) results in changes in its surface chemistry by decreasing the amounts of fluorine, OH surface groups and intercalated water. It also creates a pillaring effect between Ti3C2Tx layers pre-opening the structure and improving the accessability to active sites. The hydrazine treated material has demonstrated a greatly improved capacitance of 250 F g-1 in acidic electrolytes with an excellent cycling ability for electrodes as thick as 75 μm.Herein we show that hydrazine intercalation into 2D titanium carbide (Ti3C2-based MXene) results in changes in its surface chemistry by decreasing the amounts of fluorine, OH surface groups and intercalated water. It also creates a pillaring effect between Ti3C2Tx layers pre-opening the structure and improving the accessability to active sites. The hydrazine treated material has demonstrated a greatly improved capacitance of 250 F g-1 in acidic electrolytes with an excellent cycling ability for electrodes as thick as 75 μm. Electronic supplementary information (ESI) available: Characterization methods, additional XRD patterns (Fig. S1) and INS spectra (Fig. S2-S4). See DOI: 10.1039/c6nr01462c

  8. Structural consequences of hydrogen intercalation of epitaxial graphene on SiC(0001)

    SciTech Connect

    Emery, Jonathan D. E-mail: bedzyk@northwestern.edu; Johns, James E.; McBriarty, Martin E.; Hersam, Mark C.; Wheeler, Virginia H.; Kurt Gaskill, D.; Detlefs, Blanka; Bedzyk, Michael J. E-mail: bedzyk@northwestern.edu

    2014-10-20

    The intercalation of various atomic species, such as hydrogen, to the interface between epitaxial graphene (EG) and its SiC substrate is known to significantly influence the electronic properties of the graphene overlayers. Here, we use high-resolution X-ray reflectivity to investigate the structural consequences of the hydrogen intercalation process used in the formation of quasi-free-standing (QFS) EG/SiC(0001). We confirm that the interfacial layer is converted to a layer structurally indistinguishable from that of the overlying graphene layers. This newly formed graphene layer becomes decoupled from the SiC substrate and, along with the other graphene layers within the film, is vertically displaced by ∼2.1 Å. The number of total carbon layers is conserved during the process, and we observe no other structural changes such as interlayer intercalation or expansion of the graphene d-spacing. These results clarify the under-determined structure of hydrogen intercalated QFS-EG/SiC(0001) and provide a precise model to inform further fundamental and practical understanding of the system.

  9. Quantifying the molecular mechanism for highly stereo-selective DNA threading intercalation

    NASA Astrophysics Data System (ADS)

    Almaqwashi, Ali; Andersson, Johanna; Lincoln, Per; Rouzina, Ioulia; Westerlund, Fredrik; Williams, Mark C.

    2015-03-01

    DNA threading intercalators, such as binuclear ruthenium complexes, are regarded as potential DNA-targeted therapeutic drugs because of slow kinetics and high affinity. Recent bulk studies reported that poly(dAdT) threading intercalation by the binuclear ruthenium complex [ μ-dppzip(phen)4Ru2]4+(Piz) is highly stereo-selective. The largest fractional binding was achieved for Δ, Λ-Piz, with the Δ (right handed) configuration at the intercalating dipyridophenazine (dppz) subunit and the Λ (left handed) configuration at the distal imidazophenanthroline (ip) subunit. To quantify this highly stereo-selective molecular mechanism, we used optical tweezers to probe single λ-DNA molecules elongation due to the threading intercalation by each of Δ, Δ-Piz and Δ, Λ-Piz. While maintaining a DNA stretching force of 30 pN and a ligand concentration of 5 nM, the elongation was traced until reaching equilibrium. Then it was traced back to the free DNA extension by rinsing out the bound ligands. We found that the equilibrium elongation for Δ, Λ-Piz is 30% larger, and the affinity is 50% higher relative to Δ, Δ-Piz. Further force-dependent study will quantitatively determine the differences in the zero-force binding site size, affinity and the DNA structural dynamics for association and dissociation.

  10. Factors controlling the CO intercalation of h-BN overlayers on Ru(0001).

    PubMed

    Dong, Aiyi; Fu, Qiang; Wu, Hao; Wei, Mingming; Bao, Xinhe

    2016-09-21

    The space between a two-dimensional (2D) material overlayer and a metal surface can be regarded as a nanoreactor, in which molecule adsorption and surface reaction may occur. In this work, we present CO intercalation under a hexagonal boron nitride (h-BN) overlayer on Ru(0001) at room temperature, observed using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and scanning tunneling microscopy. Critical factors influencing the interfacial process have been investigated, including CO partial pressure, h-BN coverage, and oxygen pre-adsorption on the Ru surface. It has been identified that CO adsorption on the bare Ru surface region plays an important role in CO intercalation. Comparative studies of CO intercalation at h-BN/Ru(0001) and graphene/Ru(0001) interfaces indicate that CO starts to intercalate h-BN overlayers more easily than graphene. Temperature-programmed CO desorption experiments from h-BN/CO/Ru(0001) and graphene/CO/Ru(0001) surfaces reveal a similar confinement effect of the 2D cover on CO adsorption, which results in a more abrupt and quick CO desorption in comparison with the CO/Ru(0001) surface. PMID:27530273

  11. Optimal design of parallel triplex forming oligonucleotides containing Twisted Intercalating Nucleic Acids--TINA.

    PubMed

    Schneider, Uffe V; Mikkelsen, Nikolaj D; Jøhnk, Nina; Okkels, Limei M; Westh, Henrik; Lisby, Gorm

    2010-07-01

    Twisted intercalating nucleic acid (TINA) is a novel intercalator and stabilizer of Hoogsteen type parallel triplex formations (PT). Specific design rules for position of TINA in triplex forming oligonucleotides (TFOs) have not previously been presented. We describe a complete collection of easy and robust design rules based upon more than 2500 melting points (T(m)) determined by FRET. To increase the sensitivity of PT, multiple TINAs should be placed with at least 3 nt in-between or preferable one TINA for each half helixturn and/or whole helixturn. We find that Delta T(m) of base mismatches on PT is remarkably high (between 7.4 and 15.2 degrees C) compared to antiparallel duplexes (between 3.8 and 9.4 degrees C). The specificity of PT by Delta T(m) increases when shorter TFOs and higher pH are chosen. To increase Delta Tms, base mismatches should be placed in the center of the TFO and when feasible, A, C or T to G base mismatches should be avoided. Base mismatches can be neutralized by intercalation of a TINA on each side of the base mismatch and masked by a TINA intercalating direct 3' (preferable) or 5' of it. We predict that TINA stabilized PT will improve the sensitivity and specificity of DNA based clinical diagnostic assays. PMID:20338879

  12. Optimal design of parallel triplex forming oligonucleotides containing Twisted Intercalating Nucleic Acids—TINA

    PubMed Central

    Schneider, Uffe V.; Mikkelsen, Nikolaj D.; Jøhnk, Nina; Okkels, Limei M.; Westh, Henrik; Lisby, Gorm

    2010-01-01

    Twisted intercalating nucleic acid (TINA) is a novel intercalator and stabilizer of Hoogsteen type parallel triplex formations (PT). Specific design rules for position of TINA in triplex forming oligonucleotides (TFOs) have not previously been presented. We describe a complete collection of easy and robust design rules based upon more than 2500 melting points (Tm) determined by FRET. To increase the sensitivity of PT, multiple TINAs should be placed with at least 3 nt in-between or preferable one TINA for each half helixturn and/or whole helixturn. We find that ΔTm of base mismatches on PT is remarkably high (between 7.4 and 15.2°C) compared to antiparallel duplexes (between 3.8 and 9.4°C). The specificity of PT by ΔTm increases when shorter TFOs and higher pH are chosen. To increase ΔTms, base mismatches should be placed in the center of the TFO and when feasible, A, C or T to G base mismatches should be avoided. Base mismatches can be neutralized by intercalation of a TINA on each side of the base mismatch and masked by a TINA intercalating direct 3′ (preferable) or 5′ of it. We predict that TINA stabilized PT will improve the sensitivity and specificity of DNA based clinical diagnostic assays. PMID:20338879

  13. Temperature dependent local atomic displacements in ammonia intercalated iron selenide superconductor

    NASA Astrophysics Data System (ADS)

    Paris, E.; Simonelli, L.; Wakita, T.; Marini, C.; Lee, J.-H.; Olszewski, W.; Terashima, K.; Kakuto, T.; Nishimoto, N.; Kimura, T.; Kudo, K.; Kambe, T.; Nohara, M.; Yokoya, T.; Saini, N. L.

    2016-06-01

    Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Lix(NH3)yFe2Se2 superconductor with Tc ~ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across Tc, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity.

  14. Temperature dependent local atomic displacements in ammonia intercalated iron selenide superconductor

    PubMed Central

    Paris, E.; Simonelli, L.; Wakita, T.; Marini, C.; Lee, J.-H.; Olszewski, W.; Terashima, K.; Kakuto, T.; Nishimoto, N.; Kimura, T.; Kudo, K.; Kambe, T.; Nohara, M.; Yokoya, T.; Saini, N. L.

    2016-01-01

    Recently, ammonia-thermal reaction has been used for molecular intercalation in layered FeSe, resulting a new Lix(NH3)yFe2Se2 superconductor with Tc ~ 45 K. Here, we have used temperature dependent extended x-ray absorption fine structure (EXAFS) to investigate local atomic displacements in single crystals of this new superconductor. Using polarized EXAFS at Fe K-edge we have obtained direct information on the local Fe-Se and Fe-Fe bondlengths and corresponding mean square relative displacements (MSRD). We find that the Se-height in the intercalated system is lower than the one in the binary FeSe, suggesting compressed FeSe4 tetrahedron in the title system. Incidentally, there is hardly any effect of the intercalation on the bondlengths characteristics, revealed by the Einstein temperatures, that are similar to those found in the binary FeSe. Therefore, the molecular intercalation induces an effective compression and decouples the FeSe slabs. Furthermore, the results reveal an anomalous change in the atomic correlations across Tc, appearing as a clear decrease in the MSRD, indicating hardening of the local lattice mode. Similar response of the local lattice has been found in other families of superconductors, e.g., A15-type and cuprates superconductors. This observation suggests that local atomic correlations should have some direct correlation with the superconductivity. PMID:27276997

  15. Intercalation of heavy alkali metals (K, Rb and Cs) in the bundles of single wall nanotubes

    NASA Astrophysics Data System (ADS)

    Duclaux, L.; Méténier, K.; Lauginie, P.; Salvetat, J. P.; Bonnamy, S.; Beguin, F.

    2000-11-01

    The electric-arc discharge carbon deposits (collaret) containing Single Wall Carbon Nanotubes (SWNTs) were heat treated at 1600 °C during 2 days under N2 flow in order to eliminate the Ni catalyst by sublimation, without modifications of the SWNTs ropes. Sorting this deposit by gravity enabled to obtain in the coarsest particles higher amount of SWNTs ropes than in other particle sizes. The coarser particles of the carbon deposits were reacted with the alkali metals vapor giving intercalated samples with a MC8 composition. The intercalation led to an expansion of the 2D lattice of the SWNTs so that the alkali metals were intercalated in between the tubes within the bundles. Disordered lattices were observed after intercalation of Rb and Cs. The simulations of the X-ray diffractograms of SWNTs reacted with K, gave the best fit for three K ions occupying the inter-tubes triangular cavities. The investigations by EPR, and 13C NMR, showed that doped carbon deposits are metallic.

  16. Band-gap engineering by Bi intercalation of graphene on Ir(111)

    NASA Astrophysics Data System (ADS)

    Warmuth, Jonas; Bruix, Albert; Michiardi, Matteo; Hänke, Torben; Bianchi, Marco; Wiebe, Jens; Wiesendanger, Roland; Hammer, Bjørk; Hofmann, Philip; Khajetoorians, Alexander A.

    2016-04-01

    We report on the structural and electronic properties of a single bismuth layer intercalated underneath a graphene layer grown on an Ir(111) single crystal. Scanning tunneling microscopy (STM) reveals a hexagonal surface structure and a dislocation network upon Bi intercalation, which we attribute to a √{3 }×√{3 }R 30∘ Bi structure on the underlying Ir(111) surface. Ab initio calculations show that this Bi structure is the most energetically favorable and illustrate that STM measurements are most sensitive to C atoms in close proximity to intercalated Bi atoms. Additionally, Bi intercalation induces a band gap (Eg=0.42 eV) at the Dirac point of graphene and an overall n doping (˜0.39 eV ) as seen in angular-resolved photoemission spectroscopy. We attribute the emergence of the band gap to the dislocation network which forms favorably along certain parts of the moiré structure induced by the graphene/Ir(111) interface.

  17. Copper intercalation at the interface of graphene and Ir(111) studied by scanning tunneling microscopy

    SciTech Connect

    Sicot, M. Fagot-Revurat, Y.; Kierren, B.; Vasseur, G.; Malterre, D.

    2014-11-10

    We report on the intercalation of a submonolayer of copper at 775 K underneath graphene epitaxially grown on Ir(111) studied by means of low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) at 77 K. Nucleation and growth dynamics of Cu below graphene have been investigated, and, most importantly, the intercalation mechanism has been identified. First, LEED patterns reveal the pseudomorphic growth of Cu on Ir under the topmost graphene layer resulting in a large Cu in-plane lattice parameter expansion of about 6% compared to Cu(111). Second, large-scale STM topographs as a function of Cu coverage show that Cu diffusion on Ir below graphene exhibits a low energy barrier resulting in Cu accumulation at Ir step edges. As a result, the graphene sheet undergoes a strong edges reshaping. Finally, atomically-resolved STM images reveal a damaged graphene sheet at the atomic scale after metal intercalation. Point defects in graphene were shown to be carbon vacancies. According to these results, a Cu penetration path beneath graphene is proposed to occur via metal aided defect formation with no or poor self healing of the graphene sheet. This work illustrates the fact that Cu intercalation is harmful for graphene grown on Ir(111) at the atomic scale.

  18. Functional binders for reversible lithium intercalation into graphite in propylene carbonate and ionic liquid media

    NASA Astrophysics Data System (ADS)

    Komaba, Shinichi; Yabuuchi, Naoaki; Ozeki, Tomoaki; Okushi, Koji; Yui, Hiroharu; Konno, Kozo; Katayama, Yasushi; Miura, Takashi

    Poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), and poly(vinyl alcohol) (PVA), which have oxygen species as functional groups, were utilized as a binder for graphite electrodes, and the electrochemical reversibility of lithium intercalation was examined in PC medium and ionic liquid electrolyte, lithium bis(trifluoromethanesulfonyl)amide dissolved in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide (BMP-TFSA). Columbic efficiency of 75-80% with more than 300 mAh g -1 was achieved upon first reduction/oxidation cycle in both electrolytes using these binding polymers, which were significantly improved in comparison to a conventional PVdF binder (less than 45% of columbic efficiency for the first cycle). For the graphite-PVdF electrode, co-intercalation and/or decomposition of PC molecules solvating to Li ions were observed by the electrochemical reduction, resulting in the cracking of graphite particles. In contrast, the co-intercalation and decomposition of PC molecules and BMP cations for the first reduction process were completely suppressed for the graphite electrodes prepared with the polymers containing oxygen atoms. It was proposed that the selective permeability of lithium ions was attained by the uniform coating of the graphite particles with PAA, PMA, and PVA polymers, because the electrostatic interaction between the positively charged lithium ions and negatively charged oxygen atom in the polymer should modulate the desolvation process of lithium ions during the lithium intercalation into graphite, showing the similar functions like artificial solid-electrolyte interphase.

  19. Copper intercalation at the interface of graphene and Ir(111) studied by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Sicot, M.; Fagot-Revurat, Y.; Kierren, B.; Vasseur, G.; Malterre, D.

    2014-11-01

    We report on the intercalation of a submonolayer of copper at 775 K underneath graphene epitaxially grown on Ir(111) studied by means of low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) at 77 K. Nucleation and growth dynamics of Cu below graphene have been investigated, and, most importantly, the intercalation mechanism has been identified. First, LEED patterns reveal the pseudomorphic growth of Cu on Ir under the topmost graphene layer resulting in a large Cu in-plane lattice parameter expansion of about 6% compared to Cu(111). Second, large-scale STM topographs as a function of Cu coverage show that Cu diffusion on Ir below graphene exhibits a low energy barrier resulting in Cu accumulation at Ir step edges. As a result, the graphene sheet undergoes a strong edges reshaping. Finally, atomically-resolved STM images reveal a damaged graphene sheet at the atomic scale after metal intercalation. Point defects in graphene were shown to be carbon vacancies. According to these results, a Cu penetration path beneath graphene is proposed to occur via metal aided defect formation with no or poor self healing of the graphene sheet. This work illustrates the fact that Cu intercalation is harmful for graphene grown on Ir(111) at the atomic scale.

  20. Enhancement of electron-phonon coupling in Cs-overlayered intercalated bilayer graphene.

    PubMed

    Kleeman, J; Sugawara, K; Sato, T; Takahashi, T

    2016-05-25

    We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on cesium (Cs) intercalated bilayer graphene with a Cs overlayer (Cs-C8CsC8). Low-energy electron diffraction shows a (2  ×  2) pattern consistent with intercalation of a Cs layer similar to bulk C8Cs, in addition to the signature of a nearly commensurate superstructure created by the Cs overlayer. ARPES results reveal folding of the π bands due to the periodic (2  ×  2) potential of the intercalated Cs atoms, together with a free-electron-like state at the [Formula: see text] point. Significant mass renormalization is observed in the band dispersion near the Fermi level, indicative of strong electron-phonon coupling. Based on analysis of the self-energy, we find anisotropic electron-phonon coupling with an estimated strength of [Formula: see text]  ±  0.02 in the K-[Formula: see text] direction, and [Formula: see text] in the K-M direction. This coupling is much larger than that of other doped graphenes, and comparable to superconducting bulk GICs. We attribute this large electron-phonon coupling constant to the presence of the Cs overlayer, which highly dopes [Formula: see text] bands, and creates a structure similar to stage-I graphite intercalation compounds. PMID:27094681

  1. The Edinburgh intercalated honours BSc in pathology: evaluation of selection methods, undergraduate performance, and postgraduate career.

    PubMed Central

    Wyllie, A H; Currie, A R

    1986-01-01

    In a study of 60 students who entered the intercalated honours BSc course in pathology at the University of Edinburgh over 10 years the conventional criteria of academic excellence and motivation were shown to be appropriate for the selection of honours students. When compared with classmates who did not take the intercalated year but who had shown similar high academic ability in the preclinical course the students who had taken the honours BSc did better in the remainder of the undergraduate curriculum. Of 42 honours students, 18 (43%) entered academic careers, particularly in pathology and medicine, but there was no observed tendency for students without honours BSc to do so. Although it is impossible to establish a causal relation between taking the honours course and subsequent academic distinction, the results suggest that the intercalated honours BSc in pathology serves a useful function in introducing able students into academic careers. The findings justify the financial support made available to such students during their intercalated year by the Medical Research Council and the Scottish Education Department. PMID:3087558

  2. Standard Model for Superconductivity in Graphite Intercalation Compounds: Prediction of Optimum Tc

    NASA Astrophysics Data System (ADS)

    Takada, Yasutami

    2009-03-01

    Based on the model that was successfully applied to the explanation of superconductivity with the transition temperature Tc of about 0.1K or less in the alkali- intercalated graphite compounds such as KC8, RbC8, and CsC8 in 1982 [Y. Takada, J. Phys. Soc. Jpn. 51, 63 (1982) ], we have calculated Tc for the alkaline-earth- intercalated graphite compounds including CaC6, YbC6, and SrC6 with Tc of about 10K or less to find that the same model reproduces the observed Tc in those compounds as well, indicating that it is a standard model for superconductivity in the graphite intercalation compounds with Tc ranging over three orders of magnitude. The difference in Tc by two orders between KC8 and CaC6 can be accounted for by (i) doubling Z the valency of the metal ions, which enhances Tc by one order, and (ii) tripling m^* the effective mass of the superconducting three-dimensional electrons in the interlayer band, which also enhances Tc by one order. Enhancement of Tc well beyond 10 K is also predicted in this model, if intercalant metals are judiciously chosen so that both Z and m^* are increased further.

  3. Structural and electronic properties of Li-intercalated graphene on SiC(0001)

    NASA Astrophysics Data System (ADS)

    Caffrey, Nuala M.; Johansson, Leif I.; Xia, Chao; Armiento, Rickard; Abrikosov, Igor A.; Jacobi, Chariya

    2016-05-01

    We investigate the structural and electronic properties of Li-intercalated monolayer graphene on SiC(0001) using combined angle-resolved photoemission spectroscopy and first-principles density functional theory. Li intercalates at room temperature both at the interface between the buffer layer and SiC and between the two carbon layers. The graphene is strongly n -doped due to charge transfer from the Li atoms and two π bands are visible at the K ¯ point. After heating the sample to 300 ∘C , these π bands become sharp and have a distinctly different dispersion to that of Bernal-stacked bilayer graphene. We suggest that the Li atoms intercalate between the two carbon layers with an ordered structure, similar to that of bulk LiC6. An AA stacking of these two layers becomes energetically favourable. The π bands around the K ¯ point closely resemble the calculated band structure of a C6LiC6 system, where the intercalated Li atoms impose a superpotential on the graphene electronic structure that opens gaps at the Dirac points of the two π cones.

  4. Structure and magnetism of cobalt intercalated graphene/Ir(111) via spin-polarized STM

    NASA Astrophysics Data System (ADS)

    Decker, Regis; Brede, Jens; Atodiresei, Nicolae; Caciuc, Vasile; Bluegel, Stefan; Wiesendanger, Roland

    2013-03-01

    The presence of intercalation compounds in graphite, i.e. impurities or layer(s) trapped between carbon sheets, can lead to changes in the transport, optical and catalytic properties compared to bulk graphite, or even superconductivity. Here, we present the local structure and magnetic properties of graphene on a magnetic substrate, resolved by spin-polarized STM. The magnetic substrate is obtained by the intercalation of a cobalt layer between graphene and an Ir(111) surface. The atomic structure of the graphene layer is dominated by a highly corrugated Moiré pattern, which arises due to the incommensurability and/or twisting angle of the graphene lattice and the Co/Ir(111) surface. Within the Moiré unit cell three different regions, i.e. top, fcc, and hcp regions are identified. Interestingly, these regions show very different electronic and magnetic signatures in the experiments, defining an atomic-scale magnetic Moiré pattern. The observed spin polarization is compared to density functional theory calculations. The calculations reveal that the bonding between the graphene layer and intercalated Co layer varies from weak to strong within the Moiré unit cell. Moreover, the interaction between the graphene and the intercalated cobalt layer leads to a spin dependent charge rearrangement, which induces magnetism in graphene as observed in experiment.

  5. Bipiperidine conjugates as soluble sugar surrogates in DNA-intercalating antiproliferative polyketides.

    PubMed

    Ueberschaar, Nico; Meyer, Florian; Dahse, Hans-Martin; Hertweck, Christian

    2016-04-01

    DNA-intercalating polyketide glycosides are important leads for cancer therapeutics, yet their use is often limited by their low solubility and challenging synthetic protocols. To overcome these limitations, we employed 1,4'-bipiperidine-1'-carbamate residues as sugar surrogates in daunorubicin and chartreusin, yielding water-soluble derivatives and prodrugs with dramatically improved antiproliferative activities. PMID:26974406

  6. Synthesis and characterization of montmorillonite clay intercalated with molecular magnetic compounds

    NASA Astrophysics Data System (ADS)

    Martins, Marcel G.; Martins, Daniel O. T. A.; de Carvalho, Beatriz L. C.; Mercante, Luiza A.; Soriano, Stéphane; Andruh, Marius; Vieira, Méri D.; Vaz, Maria G. F.

    2015-08-01

    In this work montmorillonite (MMT) clay, whose matrix was modified with an ammonium salt (hexadecyltrimethylammonium bromide - CTAB), was employed as an inorganic host for the intercalation of three different molecular magnetic compounds through ion exchange: a nitronyl nitroxide derivative 2-[4-(N-ethyl)-pyridinium]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (p-EtRad+) and two binuclear coordination compounds, [Ni(valpn)Ln]3+, where H2valpn stands for 1,3-propanediyl-bis(2-iminomethylene-6-methoxy-phenol), and Ln=GdIII; DyIII. The pristine MMT and the intercalated materials were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurements. The X-ray diffraction data analysis showed an increase of the interlamellar space of the intercalated MMT, indicating the intercalation of the magnetic compounds. Furthermore, the magnetic properties of the hybrid compounds were investigated, showing similar behavior as the pure magnetic guest species.

  7. Europium underneath graphene on Ir(111): Intercalation mechanism, magnetism, and band structure

    NASA Astrophysics Data System (ADS)

    Schumacher, Stefan; Huttmann, Felix; Petrović, Marin; Witt, Christian; Förster, Daniel F.; Vo-Van, Chi; Coraux, Johann; Martínez-Galera, Antonio J.; Sessi, Violetta; Vergara, Ignacio; Rückamp, Reinhard; Grüninger, Markus; Schleheck, Nicolas; Meyer zu Heringdorf, Frank; Ohresser, Philippe; Kralj, Marko; Wehling, Tim O.; Michely, Thomas

    2014-12-01

    The intercalation of Eu underneath Gr on Ir(111) is comprehensively investigated by microscopic, magnetic, and spectroscopic measurements, as well as by density functional theory. Depending on the coverage, the intercalated Eu atoms form either a (2 ×2 ) or a (√{3 }×√{3 }) R 30∘ superstructure with respect to Gr. We investigate the mechanisms of Eu penetration through a nominally closed Gr sheet and measure the electronic structures and magnetic properties of the two intercalation systems. Their electronic structures are rather similar. Compared to Gr on Ir(111), the Gr bands in both systems are essentially rigidly shifted to larger binding energies resulting in n doping. The hybridization of the Ir surface state S1 with Gr states is lifted, and the moiré superperiodic potential is strongly reduced. In contrast, the magnetic behavior of the two intercalation systems differs substantially, as found by x-ray magnetic circular dichroism. The (2 ×2 ) Eu structure displays plain paramagnetic behavior, whereas for the (√{3 }×√{3 }) R 30∘ structure the large zero-field susceptibility indicates ferromagnetic coupling, despite the absence of hysteresis at 10 K. For the latter structure, a considerable easy-plane magnetic anisotropy is observed and interpreted as shape anisotropy.

  8. Effect of Chemical Lithium Intercalation into Rutile TiO2 Nanorods

    SciTech Connect

    Vijayakumar, M.; Kerisit, Sebastien N.; Wang, Chong M.; Nie, Zimin; Rosso, Kevin M.; Yang, Zhenguo; Graff, Gordon L.; Liu, Jun; Hu, Jian Z.

    2009-08-13

    Rutile TiO2 nanorods were synthesized by hydrolysis of TiCl4 followed by a hydrothermal method. Lithium insertion into the rutile nanorods was achieved by a chemical lithium intercalation process. The structural evolution of nano-structured rutile upon lithium intercalation was characterized by several experimental techniques, namely, XRD, TEM and 6Li MAS NMR. The XRD and TEM studies indicate the formation of a new lithium titanate phase (LixTiO2) during lithium intercalation. Additionally, SAED patterns show that the lithium titanate phase has cubic symmetry. Finally, ultra-high magnetic field (21.1T) 6Li MAS NMR reveals that the lithium titanate phase adopts two different structures depending on lithium content. Taken together, the three techniques consistently show that the intercalation of lithium into rutile TiO2 nanorods causes two consecutive structural phase transformations to lithium titanate phases with spinel (Fd m) and rocksalt (Fm m) structures at x=0.46 and 0.88, respectively. In addition, the broad line widths in the 6Li MAS NMR spectrum of the rocksalt phase are indicative of a disordered structure. Density functional theory calculations of the rutile, spinel and rocksalt bulk phases as a function of lithium content corroborate the observed phase transformations. These phase transitions could account for the large irreversible capacity loss of nano-structured rutile anodes observed in electrochemical cycling experiments.

  9. Structure, molecular simulation, and release of aspirin from intercalated Zn-Al-layered double hydroxides.

    PubMed

    Meng, Zilin; Li, Xiaowei; Lv, Fengzhu; Zhang, Qian; Chu, Paul K; Zhang, Yihe

    2015-11-01

    Aspirin or acetylsalicylic acid (AA), a non-steroidal anti-inflammatory drug, is intercalated into Zn-Al-layered double hydroxides (ZnAl-LDHs) by co-precipitation and reconstruction methods. The composition, structure, and morphology of the intercalated products as well as their release behavior are determined experimentally and theoretically by Material Studio 5.5. Experimental results disclose the strong interaction between the LDHs sheets and AA in the intercalated ZnAl-LDHs produced by co-precipitation and slow release of AA from the intercalated ZnAl-LDHs in both phosphate buffered saline (PBS) and borate buffered saline (BBS) solutions. The percentage of AA released from the ZnAl-LDHs prepared by both methods in PBS (96.87% and 98.12%) are much more than those in BBS (68.59% and 81.22%) implying that both H4BO4(-) and H2PO4(-) can exchange with AA in the ZnAl-LDHs. After AA is released to PBS, ZnAl-LDHs break into small pieces. The experimental results are explained theoretically based on the calculation of the bonding energy between the anions and LDHs sheets as well as the AlO bond length change in the LDHs sheets. PMID:26263219

  10. Enhancement of electron–phonon coupling in Cs-overlayered intercalated bilayer graphene

    NASA Astrophysics Data System (ADS)

    Kleeman, J.; Sugawara, K.; Sato, T.; Takahashi, T.

    2016-05-01

    We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) on cesium (Cs) intercalated bilayer graphene with a Cs overlayer (Cs-C8CsC8). Low-energy electron diffraction shows a (2  ×  2) pattern consistent with intercalation of a Cs layer similar to bulk C8Cs, in addition to the signature of a nearly commensurate superstructure created by the Cs overlayer. ARPES results reveal folding of the π bands due to the periodic (2  ×  2) potential of the intercalated Cs atoms, together with a free-electron-like state at the Γ point. Significant mass renormalization is observed in the band dispersion near the Fermi level, indicative of strong electron–phonon coupling. Based on analysis of the self-energy, we find anisotropic electron–phonon coupling with an estimated strength of λ =0.38   ±  0.02 in the K-Γ direction, and λ =0.60+/- 0.02 in the K-M direction. This coupling is much larger than that of other doped graphenes, and comparable to superconducting bulk GICs. We attribute this large electron–phonon coupling constant to the presence of the Cs overlayer, which highly dopes {π\\ast} bands, and creates a structure similar to stage-I graphite intercalation compounds.

  11. Graphite intercalation compounds - new materials in the technology of electroslag remelting of steel

    SciTech Connect

    Yaroshenko, A.P.; Radchenko, V.N.; Savos`kin, M.V.; Ivanov, E.L.; Popov, A.F.

    1995-10-10

    Thermally cleaving graphite intercalation compounds have been used for producing heat-insulating and gas-tight coatings during electroslag remelting of steel, which decreases the specific consumption of electric power and the burnout of highly active components of the alloy. The authors have shown that thermally cleaved graphite coatings on the surface of slag baths can almost completely prevent heat loss.

  12. Impact of Infralimbic Inputs on Intercalated Amygdale Neurons: A Biophysical Modeling Study

    ERIC Educational Resources Information Center

    Li, Guoshi; Amano, Taiju; Pare, Denis; Nair, Satish S.

    2011-01-01

    Intercalated (ITC) amygdala neurons regulate fear expression by controlling impulse traffic between the input (basolateral amygdala; BLA) and output (central nucleus; Ce) stations of the amygdala for conditioned fear responses. Previously, stimulation of the infralimbic (IL) cortex was found to reduce fear expression and the responsiveness of Ce…

  13. Ca intercalated bilayer graphene as a thinnest limit of superconducting C6Ca

    PubMed Central

    Kanetani, Kohei; Sugawara, Katsuaki; Sato, Takafumi; Shimizu, Ryota; Iwaya, Katsuya; Hitosugi, Taro; Takahashi, Takashi

    2012-01-01

    Success in isolating a 2D graphene sheet from bulky graphite has triggered intensive studies of its physical properties as well as its application in devices. Graphite intercalation compounds (GICs) have provided a platform of exotic quantum phenomena such as superconductivity, but it is unclear whether such intercalation is feasible in the thinnest 2D limit (i.e., bilayer graphene). Here we report a unique experimental realization of 2D GIC, by fabricating calcium-intercalated bilayer graphene C6CaC6 on silicon carbide. We have investigated the structure and electronic states by scanning tunneling microscopy and angle-resolved photoemission spectroscopy. We observed a free-electron–like interlayer band at the Brillouin-zone center, which is thought to be responsible for the superconductivity in 3D GICs, in addition to a large π* Fermi surface at the zone boundary. The present success in fabricating Ca-intercalated bilayer graphene would open a promising route to search for other 2D superconductors as well as to explore its application in devices. PMID:23139407

  14. Synthesis, characterization, and controlled release antibacterial behavior of antibiotic intercalated Mg–Al layered double hydroxides

    SciTech Connect

    Wang, Yi; Zhang, Dun

    2012-11-15

    Graphical abstract: The antibiotic anion released from Mg–Al LDHs provides a controlled release antibacterial activity against the growth of Micrococcus lysodeikticus in 3.5% NaCl solution. Highlights: ► Antibiotic anion intercalated LDHs were synthesized and characterized. ► The ion-exchange one is responsible for the release process. ► The diffusion through particle is the release rate limiting step. ► LDHs loaded with antibiotic anion have high antibacterial capabilities. -- Abstract: Antibiotic–inorganic clay composites including four antibiotic anions, namely, benzoate (BZ), succinate (SU), benzylpenicillin (BP), and ticarcillin (TC) anions, intercalated Mg–Al layered double hydroxides (LDHs) were synthesized via ion-exchange. Powder X-ray diffraction and Fourier transform infrared spectrum analyses showed the successful intercalation of antibiotic anion into the LDH interlayer. BZ and BP anions were accommodated in the interlayer region as a bilayer, whereas SU and TC anions were intercalated in a monolayer arrangement. Kinetic simulation of the release data indicated that ion-exchange was responsible for the release process, and the diffusion through the particles was the rate-limiting step. The antibacterial capabilities of LDHs loaded with antibiotic anion toward Micrococcus lysodeikticus growth were analyzed using a turbidimetric method. Significant high inhibition rate was observed when LDH nanohybrid was introduced in 3.5% NaCl solution. Therefore, this hybrid material may be applied as nanocontainer in active antifouling coating for marine equipment.

  15. Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

    NASA Astrophysics Data System (ADS)

    Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

    2016-01-01

    A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

  16. Direct intercalation of cisplatin into zirconium phosphate nanoplatelets for potential cancer nanotherapy

    NASA Astrophysics Data System (ADS)

    Díaz, Agustín; González, Millie L.; Pérez, Riviam J.; David, Amanda; Mukherjee, Atashi; Báez, Adriana; Clearfield, Abraham; Colón, Jorge L.

    2013-11-01

    We report the use of zirconium phosphate (ZrP) nanoplatelets for the encapsulation of the anticancer drug cisplatin and its delivery to tumor cells. Cisplatin was intercalated into ZrP by direct ion exchange and was tested in vitro for cytotoxicity in the human breast cancer (MCF-7) cell line. The structural characterization of the intercalated cisplatin in ZrP suggests that during the intercalation process, the chloride ligands of the cisplatin complex were substituted by phosphate groups within the layers. Consequently, a new phosphate phase with the platinum complex directly bound to ZrP (cisPt@ZrP) is produced with an interlayer distance of 9.3 Å. The in vitro release profile of the intercalated drug upon a pH stimulus shows that at low pH under lysosomal conditions the platinum complex is released with simultaneous hydrolysis of the zirconium phosphate material, while at higher pH the complex is not released. Experiments with the MCF-7 cell line show that cisPt@ZrP reduced the cell viability up to 40%. The cisPt@ZrP intercalation product is envisioned as a future nanotherapy agent against cancer. Taking advantage of the shape and sizes of the ZrP particles and controlled release of the drug at low pH, it is intended to exploit the enhanced permeability and retention effect of tumors, as well as their intrinsic acidity, for the destruction of malignant cells.We report the use of zirconium phosphate (ZrP) nanoplatelets for the encapsulation of the anticancer drug cisplatin and its delivery to tumor cells. Cisplatin was intercalated into ZrP by direct ion exchange and was tested in vitro for cytotoxicity in the human breast cancer (MCF-7) cell line. The structural characterization of the intercalated cisplatin in ZrP suggests that during the intercalation process, the chloride ligands of the cisplatin complex were substituted by phosphate groups within the layers. Consequently, a new phosphate phase with the platinum complex directly bound to ZrP (cisPt@ZrP) is

  17. Simulated structural and magnetic behavior of Mn-Ti intercalated dichalcogenide crystals.

    PubMed

    Roth, M W; Wandling, B; Kidd, T E; Shand, P M; Stollenwerk, A

    2016-05-11

    We present the results of extensive Monte Carlo simulations of intercalated manganese-titanium (Mn-Ti) layered TiS2 crystals. The computational model involves mixtures of Mn and Ti in various percentages placed on a triangular lattice with fixed lattice sites and up to five layers. The range of concentrations of intercalated Mn studied was 5%  ⩽  X Mn  ⩽  33% and for Ti, 0%  ⩽  X Ti  ⩽  15%, where X A denotes the percentage of the total number of lattice sites occupied by species A. The species are allowed to interact spatially through a screened Coulomb potential and magnetically with external and RKKY field terms. Structurally, the pure Mn systems present as disordered at very low densities and evolve through a 2  ×  2 structure (perfect at X Mn  =  25%) up to a [Formula: see text]  ×  [Formula: see text] lattice (perfect at X Mn  =  33%), with variations of the two 'perfect' lattice structures depending on density. Changes in density for pure Mn systems as well as those intercalated with both Mn and Ti dramatically affects the system's structural and magnetic properties, and the magnetic behavior of various morphological features present in the system are discussed. The RKKY interaction is adjusted based on the intercalant compositions and is very sensitive to structural variations in the intercalant layers. The composition ranges studied here encompass and exceed those that are experimentally accessible, which helps place experimentally relevant densities in perspective. PMID:27058645

  18. Simulated structural and magnetic behavior of Mn–Ti intercalated dichalcogenide crystals

    NASA Astrophysics Data System (ADS)

    Roth, M. W.; Wandling, B.; Kidd, T. E.; Shand, P. M.; Stollenwerk, A.

    2016-05-01

    We present the results of extensive Monte Carlo simulations of intercalated manganese–titanium (Mn–Ti) layered TiS2 crystals. The computational model involves mixtures of Mn and Ti in various percentages placed on a triangular lattice with fixed lattice sites and up to five layers. The range of concentrations of intercalated Mn studied was 5%  ⩽  X Mn  ⩽  33% and for Ti, 0%  ⩽  X Ti  ⩽  15%, where X A denotes the percentage of the total number of lattice sites occupied by species A. The species are allowed to interact spatially through a screened Coulomb potential and magnetically with external and RKKY field terms. Structurally, the pure Mn systems present as disordered at very low densities and evolve through a 2  ×  2 structure (perfect at X Mn  =  25%) up to a \\sqrt{3}   ×  \\sqrt{3} lattice (perfect at X Mn  =  33%), with variations of the two ‘perfect’ lattice structures depending on density. Changes in density for pure Mn systems as well as those intercalated with both Mn and Ti dramatically affects the system’s structural and magnetic properties, and the magnetic behavior of various morphological features present in the system are discussed. The RKKY interaction is adjusted based on the intercalant compositions and is very sensitive to structural variations in the intercalant layers. The composition ranges studied here encompass and exceed those that are experimentally accessible, which helps place experimentally relevant densities in perspective.

  19. New X-ray insight into oxygen intercalation in epitaxial graphene grown on 4H-SiC(0001)

    SciTech Connect

    Kowalski, G. Tokarczyk, M.; Dąbrowski, P.; Ciepielewski, P.; Możdżonek, M.; Strupiński, W.; Baranowski, J. M.

    2015-03-14

    Efficient control of intercalation of epitaxial graphene by specific elements is a way to change properties of the graphene. Results of several experimental techniques, such as X-ray photoelectron spectroscopy, micro-Raman mapping, reflectivity, attenuated total reflection, X-ray diffraction, and X-ray reflectometry, gave a new insight into the intercalation of oxygen in the epitaxial graphene grown on 4H-SiC(0001). These results confirmed that oxygen intercalation decouples the graphene buffer layer from the 4H-SiC surface and converts it into the graphene layer. However, in contrast to the hydrogen intercalation, oxygen does not intercalate between carbon planes (in the case of few layer graphene) and the interlayer spacing stays constant at the level of 3.35–3.32 Å. Moreover, X-ray reflectometry showed the presence of an oxide layer having the thickness of about 0.8 Å underneath the graphene layers. Apart from the formation of the nonuniform thin oxide layer, generation of defects in graphene caused by oxygen was also evidenced. Last but not least, water islands underneath defected graphene regions in both intercalated and non-intercalated samples were most probably revealed. These water islands are formed in the case of all the samples stored under ambient laboratory conditions. Water islands can be removed from underneath the few layer graphene stacks by relevant thermal treatment or by UV illumination.

  20. Charge Transfer in FeOCl Intercalation Compounds and its Pressure Dependence: An X-ray Spectroscopic Study

    SciTech Connect

    I Jarrige; Y Cai; S Shieh; H Ishii; N Hiraoka; S Karna; W Li

    2011-12-31

    We present a study of charge transfer in Na-intercalated FeOCl and polyaniline-intercalated FeOCl using high-resolution x-ray absorption spectroscopy and resonant x-ray emission spectroscopy at the Fe-K edge. By comparing the experimental data with ab initio simulations, we are able to unambiguously distinguish the spectral changes which appear due to intercalation into those of electronic origin and those of structural origin. For both systems, we find that about 25% of the Fe sites are reduced to Fe{sup 2+} via charge transfer between FeOCl and the intercalate. This is about twice as large as the Fe{sup 2+} fraction reported in studies using Moessbauer spectroscopy. This discrepancy is ascribed to the fact that the charge transfer occurs on the same time scale as the Moessbauer effect itself. Our result suggests that every intercalated atom or molecule is involved in the charge-transfer process, thus making this process a prerequisite for intercalation. The Fe{sup 2+} fraction is found to increase with pressure for polyaniline-FeOCl, hinting at an enhancement of the conductivity in the FeOCl intercalation compounds under pressure.

  1. The DNA intercalating alkaloid cryptolepine interferes with topoisomerase II and inhibits primarily DNA synthesis in B16 melanoma cells.

    PubMed

    Bonjean, K; De Pauw-Gillet, M C; Defresne, M P; Colson, P; Houssier, C; Dassonneville, L; Bailly, C; Greimers, R; Wright, C; Quetin-Leclercq, J; Tits, M; Angenot, L

    1998-04-14

    Cryptolepine hydrochloride is an indoloquinoline alkaloid isolated from the roots of Cryptolepis sanguinolenta. It is characterized by a multiplicity of host-mediated biological activities, including antibacterial, antiviral, and antimalarial properties. To date, the molecular basis for its diverse biological effects remains largely uncertain. Several lines of evidence strongly suggest that DNA might correspond to its principal cellular target. Consequently, we studied the strength and mode of binding to DNA of cryptolepine by means of absorption, fluorescence, circular, and linear dichroism, as well as by a relaxation assay using DNA topoisomerases. The results of various optical and gel electrophoresis techniques converge to reveal that the alkaloid binds tightly to DNA and behaves as a typical intercalating agent. In DNAase I footprinting experiments it was found that the drug interacts preferentially with GC-rich sequences and discriminates against homo-oligomeric runs of A and T. This study has also led to the discovery that cryptolepine is a potent topoisomerase II inhibitor and a promising antitumor agent. It stabilizes topoisomerase II-DNA covalent complexes and stimulates the cutting of DNA at a subset of preexisting topoisomerase II cleavage sites. Taking advantage of the fluorescence of the indoloquinoline chromophore, fluorescence microscopy was used to map cellular uptake of the drug. Cryptolepine easily crosses the cell membranes and accumulates selectively into the nuclei rather than in the cytoplasm of B16 melanoma cells. Quantitative analyses of DNA in cells after Feulgen reaction and image cytometry reveal that the drug blocks the cell cycle in G2/M phases. It is also shown that the alkaloid is more potent at inhibiting DNA synthesis rather than RNA and protein synthesis. Altogether, the results provide direct evidence that DNA is the primary target of cryptolepine and suggest that this alkaloid is a valid candidate for the development of tumor

  2. 14 CFR 406.143 - Discovery.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Discovery. 406.143 Section 406.143... Transportation Adjudications § 406.143 Discovery. (a) Initiation of discovery. Any party may initiate discovery... after a complaint has been filed. (b) Methods of discovery. The following methods of discovery...

  3. 5 CFR 1201.73 - Discovery procedures.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 5 Administrative Personnel 3 2014-01-01 2014-01-01 false Discovery procedures. 1201.73 Section... AND PROCEDURES Procedures for Appellate Cases Discovery § 1201.73 Discovery procedures. (a) Initiating discovery. A party seeking discovery must start the process by serving a request for discovery on...

  4. 14 CFR 406.143 - Discovery.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Discovery. 406.143 Section 406.143... Transportation Adjudications § 406.143 Discovery. (a) Initiation of discovery. Any party may initiate discovery... after a complaint has been filed. (b) Methods of discovery. The following methods of discovery...

  5. 14 CFR 406.143 - Discovery.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Discovery. 406.143 Section 406.143... Transportation Adjudications § 406.143 Discovery. (a) Initiation of discovery. Any party may initiate discovery... after a complaint has been filed. (b) Methods of discovery. The following methods of discovery...

  6. The Discovery Channel Telescope

    NASA Astrophysics Data System (ADS)

    Millis, R. L.; Dunham, E. W.; Sebring, T. A.; Smith, B. W.; de Kock, M.; Wiecha, O.

    2004-11-01

    The Discovery Channel Telescope (DCT) is a 4.2-m telescope to be built at a new site near Happy Jack, Arizona. The DCT features a large prime focus mosaic CCD camera with a 2-degree-diameter field of view especially designed for surveys of KBOs, Centaurs, NEAs and other moving or time-variable targets. The telescope can be switched quickly to a Ritchey-Chretien configuration for optical/IR spectroscopy or near-IR imaging. This flexibility allows timely follow-up physical studies of high priority objects discovered in survey mode. The ULE (ultra-low-expansion) meniscus primary and secondary mirror blanks for the telescope are currently in fabrication by Corning Glass. Goodrich Aerospace, Vertex RSI, M3 Engineering and Technology Corp., and e2v Technologies have recently completed in-depth conceptual design studies of the optics, mount, enclosure, and mosaic focal plane, respectively. The results of these studies were subjected to a formal design review in July, 2004. Site testing at the 7760-ft altitude Happy Jack site began in 2001. Differential image motion observations from 117 nights since January 1, 2003 gave median seeing of 0.84 arcsec FWHM, and the average of the first quartile was 0.62 arcsec. The National Environmental Policy Act (NEPA) process for securing long-term access to this site on the Coconino National Forest is nearing completion and ground breaking is expected in the spring of 2005. The Discovery Channel Telescope is a project of the Lowell Observatory with major financial support from Discovery Communications, Inc. (DCI). DCI plans ongoing television programming featuring the construction of the telescope and the research ultimately undertaken with the DCT. An additional partner can be accommodated in the project. Interested parties should contact the lead author.

  7. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    DOEpatents

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  8. Effect of Metal Ion Intercalation on the Structure of MXene and Water Dynamics on its Internal Surfaces.

    PubMed

    Osti, Naresh C; Naguib, Michael; Ostadhossein, Alireza; Xie, Yu; Kent, Paul R C; Dyatkin, Boris; Rother, Gernot; Heller, William T; van Duin, Adri C T; Gogotsi, Yury; Mamontov, Eugene

    2016-04-13

    MXenes are a recently discovered class of 2D materials with an excellent potential for energy storage applications. Because MXene surfaces are hydrophilic and attractive interaction forces between the layers are relatively weak, water molecules can spontaneously intercalate at ambient humidity and significantly influence the key properties of this 2D material. Using complementary X-ray and neutron scattering techniques, we demonstrate that intercalation with potassium cations significantly improves structural homogeneity and water stability in MXenes. In agreement with molecular dynamics simulations, intercalated potassium ions reduce the water self-diffusion coefficient by 2 orders of magnitude, suggesting greater stability of hydrated MXene against changing environmental conditions. PMID:27010763

  9. Drug discovery in jeopardy

    PubMed Central

    Cuatrecasas, Pedro

    2006-01-01

    Despite striking advances in the biomedical sciences, the flow of new drugs has slowed to a trickle, impairing therapeutic advances as well as the commercial success of drug companies. Reduced productivity in the drug industry is caused mainly by corporate policies that discourage innovation. This is compounded by various consequences of mega-mergers, the obsession for blockbuster drugs, the shift of control of research from scientists to marketers, the need for fast sales growth, and the discontinuation of development compounds for nontechnical reasons. Lessons from the past indicate that these problems can be overcome, and herein, new and improved directions for drug discovery are suggested. PMID:17080187

  10. Efficient exact motif discovery

    PubMed Central

    Marschall, Tobias; Rahmann, Sven

    2009-01-01

    Motivation: The motif discovery problem consists of finding over-represented patterns in a collection of biosequences. It is one of the classical sequence analysis problems, but still has not been satisfactorily solved in an exact and efficient manner. This is partly due to the large number of possibilities of defining the motif search space and the notion of over-representation. Even for well-defined formalizations, the problem is frequently solved in an ad hoc manner with heuristics that do not guarantee to find the best motif. Results: We show how to solve the motif discovery problem (almost) exactly on a practically relevant space of IUPAC generalized string patterns, using the p-value with respect to an i.i.d. model or a Markov model as the measure of over-representation. In particular, (i) we use a highly accurate compound Poisson approximation for the null distribution of the number of motif occurrences. We show how to compute the exact clump size distribution using a recently introduced device called probabilistic arithmetic automaton (PAA). (ii) We define two p-value scores for over-representation, the first one based on the total number of motif occurrences, the second one based on the number of sequences in a collection with at least one occurrence. (iii) We describe an algorithm to discover the optimal pattern with respect to either of the scores. The method exploits monotonicity properties of the compound Poisson approximation and is by orders of magnitude faster than exhaustive enumeration of IUPAC strings (11.8 h compared with an extrapolated runtime of 4.8 years). (iv) We justify the use of the proposed scores for motif discovery by showing our method to outperform other motif discovery algorithms (e.g. MEME, Weeder) on benchmark datasets. We also propose new motifs on Mycobacterium tuberculosis. Availability and Implementation: The method has been implemented in Java. It can be obtained from http://ls11-www

  11. [The discovery of insulin].

    PubMed

    Lestradet, H

    1996-02-01

    When a medical problem is intensively studied by many teams in the world, it is frequent to see the solution found simultaneously in different countries. However that was not exactly the case concerning the extraction of a potent insulin able to cure Diabetes Mellitus. It seems necessary, seventy five years later, when passions are quenched, to reconsider the chronology of the history and put Paolesco but also Collip at the right places much before Banting and Best to whom, by a curious misinterpretation of facts, was attributed the priority of this fundamental discovery. PMID:8705382

  12. Research Discoveries After Kubin

    PubMed Central

    Vensko, Nancy W.; Ferguson, Steven M.

    2010-01-01

    This paper will discuss commercializing discoveries made at research organizations, particularly with a view to the In re Kubin case, decided April 3, 2009, by the Federal Circuit. Here, the existence of a general method of isolating DNA molecules was held to be relevant to the question whether the DNA molecules themselves would have been obvious under § 103 of the patent act. How are DNA inventions patented anyway? What does it take for academic research to reach patients? How might the decision of In re Kubin effect research commercialization and technology transfer? PMID:20543971

  13. Network discovery with DCM

    PubMed Central

    Friston, Karl J.; Li, Baojuan; Daunizeau, Jean; Stephan, Klaas E.

    2011-01-01

    This paper is about inferring or discovering the functional architecture of distributed systems using Dynamic Causal Modelling (DCM). We describe a scheme that recovers the (dynamic) Bayesian dependency graph (connections in a network) using observed network activity. This network discovery uses Bayesian model selection to identify the sparsity structure (absence of edges or connections) in a graph that best explains observed time-series. The implicit adjacency matrix specifies the form of the network (e.g., cyclic or acyclic) and its graph-theoretical attributes (e.g., degree distribution). The scheme is illustrated using functional magnetic resonance imaging (fMRI) time series to discover functional brain networks. Crucially, it can be applied to experimentally evoked responses (activation studies) or endogenous activity in task-free (resting state) fMRI studies. Unlike conventional approaches to network discovery, DCM permits the analysis of directed and cyclic graphs. Furthermore, it eschews (implausible) Markovian assumptions about the serial independence of random fluctuations. The scheme furnishes a network description of distributed activity in the brain that is optimal in the sense of having the greatest conditional probability, relative to other networks. The networks are characterised in terms of their connectivity or adjacency matrices and conditional distributions over the directed (and reciprocal) effective connectivity between connected nodes or regions. We envisage that this approach will provide a useful complement to current analyses of functional connectivity for both activation and resting-state studies. PMID:21182971

  14. Automated Supernova Discovery (Abstract)

    NASA Astrophysics Data System (ADS)

    Post, R. S.

    2015-12-01

    (Abstract only) We are developing a system of robotic telescopes for automatic recognition of Supernovas as well as other transient events in collaboration with the Puckett Supernova Search Team. At the SAS2014 meeting, the discovery program, SNARE, was first described. Since then, it has been continuously improved to handle searches under a wide variety of atmospheric conditions. Currently, two telescopes are used to build a reference library while searching for PSN with a partial library. Since data is taken every night without clouds, we must deal with varying atmospheric and high background illumination from the moon. Software is configured to identify a PSN, reshoot for verification with options to change the run plan to acquire photometric or spectrographic data. The telescopes are 24-inch CDK24, with Alta U230 cameras, one in CA and one in NM. Images and run plans are sent between sites so the CA telescope can search while photometry is done in NM. Our goal is to find bright PSNs with magnitude 17.5 or less which is the limit of our planned spectroscopy. We present results from our first automated PSN discoveries and plans for PSN data acquisition.

  15. Network discovery with DCM.

    PubMed

    Friston, Karl J; Li, Baojuan; Daunizeau, Jean; Stephan, Klaas E

    2011-06-01

    This paper is about inferring or discovering the functional architecture of distributed systems using Dynamic Causal Modelling (DCM). We describe a scheme that recovers the (dynamic) Bayesian dependency graph (connections in a network) using observed network activity. This network discovery uses Bayesian model selection to identify the sparsity structure (absence of edges or connections) in a graph that best explains observed time-series. The implicit adjacency matrix specifies the form of the network (e.g., cyclic or acyclic) and its graph-theoretical attributes (e.g., degree distribution). The scheme is illustrated using functional magnetic resonance imaging (fMRI) time series to discover functional brain networks. Crucially, it can be applied to experimentally evoked responses (activation studies) or endogenous activity in task-free (resting state) fMRI studies. Unlike conventional approaches to network discovery, DCM permits the analysis of directed and cyclic graphs. Furthermore, it eschews (implausible) Markovian assumptions about the serial independence of random fluctuations. The scheme furnishes a network description of distributed activity in the brain that is optimal in the sense of having the greatest conditional probability, relative to other networks. The networks are characterised in terms of their connectivity or adjacency matrices and conditional distributions over the directed (and reciprocal) effective connectivity between connected nodes or regions. We envisage that this approach will provide a useful complement to current analyses of functional connectivity for both activation and resting-state studies. PMID:21182971

  16. STS-82 Discovery Launch

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Space Shuttle Discovery cuts a bright swath through the early-morning darkness as it lifts off from Launch Pad 39A on a scheduled 10-day flight to service the Hubble Space Telescope (HST). Liftoff of Mission STS-82 occurred on-time at 3:55:17 a.m. EST, Feb. 11, 1997. Leading the veteran crew is Mission Commander Kenneth D. Bowersox. Scott J. 'Doc' Horowitz is the pilot. Mark C. Lee is the payload commander. Rounding out the seven-member crew are Mission Specialists Steven L. Smith, Gregory J. Harbaugh, Joseph R. 'Joe' Tanner and Steven A. Hawley. Four of the astronauts will be divided into two teams to perform the scheduled four back-to-back extravehicular activities (EVAs) or spacewalks. Lee and Smith will team up for EVAs 1 and 3 on flight days 4 and 6; Harbaugh and Tanner will perform EVAs 2 and 4 on flight days 5 and 7. Among the tasks will be to replace two outdated scientific instruments with two new instruments the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). This is the second servicing mission for HST, which was originally deployed in 1990 and designed to be serviced on-orbit about every three years. Hubble was first serviced in 1993. STS-82 is the second of eight planned flights in 1997. It is the 22nd flight of Discovery and the 82nd Shuttle mission.

  17. Causality discovery technology

    NASA Astrophysics Data System (ADS)

    Chen, M.; Ertl, T.; Jirotka, M.; Trefethen, A.; Schmidt, A.; Coecke, B.; Bañares-Alcántara, R.

    2012-11-01

    Causality is the fabric of our dynamic world. We all make frequent attempts to reason causation relationships of everyday events (e.g., what was the cause of my headache, or what has upset Alice?). We attempt to manage causality all the time through planning and scheduling. The greatest scientific discoveries are usually about causality (e.g., Newton found the cause for an apple to fall, and Darwin discovered natural selection). Meanwhile, we continue to seek a comprehensive understanding about the causes of numerous complex phenomena, such as social divisions, economic crisis, global warming, home-grown terrorism, etc. Humans analyse and reason causality based on observation, experimentation and acquired a priori knowledge. Today's technologies enable us to make observations and carry out experiments in an unprecedented scale that has created data mountains everywhere. Whereas there are exciting opportunities to discover new causation relationships, there are also unparalleled challenges to benefit from such data mountains. In this article, we present a case for developing a new piece of ICT, called Causality Discovery Technology. We reason about the necessity, feasibility and potential impact of such a technology.

  18. Discovery and Classification in Astronomy

    NASA Astrophysics Data System (ADS)

    Dick, Steven J.

    2012-01-01

    Three decades after Martin Harwit's pioneering Cosmic Discovery (1981), and following on the recent IAU Symposium "Accelerating the Rate of Astronomical Discovery,” we have revisited the problem of discovery in astronomy, emphasizing new classes of objects. 82 such classes have been identified and analyzed, including 22 in the realm of the planets, 36 in the realm of the stars, and 24 in the realm of the galaxies. We find an extended structure of discovery, consisting of detection, interpretation and understanding, each with its own nuances and a microstructure including conceptual, technological and social roles. This is true with a remarkable degree of consistency over the last 400 years of telescopic astronomy, ranging from Galileo's discovery of satellites, planetary rings and star clusters, to the discovery of quasars and pulsars. Telescopes have served as "engines of discovery” in several ways, ranging from telescope size and sensitivity (planetary nebulae and spiral galaxies), to specialized detectors (TNOs) and the opening of the electromagnetic spectrum for astronomy (pulsars, pulsar planets, and most active galaxies). A few classes (radiation belts, the solar wind and cosmic rays), were initially discovered without the telescope. Classification also plays an important role in discovery. While it might seem that classification marks the end of discovery, or a post-discovery phase, in fact it often marks the beginning, even a pre-discovery phase. Nowhere is this more clearly seen than in the classification of stellar spectra, long before dwarfs, giants and supergiants were known, or their evolutionary sequence recognized. Classification may also be part of a post-discovery phase, as in the MK system of stellar classification, constructed after the discovery of stellar luminosity classes. Some classes are declared rather than discovered, as in the case of gas and ice giant planets, and, infamously, Pluto as a dwarf planet.

  19. Hubble: 20 Years of Discovery

    NASA Video Gallery

    Hubble's discoveries have revolutionized nearly all areas of current astronomical research from planetary science to cosmology. Actor and writer Brent Spiner narrates a visual journey back in time ...

  20. Optogenetics enlightens neuroscience drug discovery.

    PubMed

    Song, Chenchen; Knöpfel, Thomas

    2016-02-01

    Optogenetics - the use of light and genetics to manipulate and monitor the activities of defined cell populations - has already had a transformative impact on basic neuroscience research. Now, the conceptual and methodological advances associated with optogenetic approaches are providing fresh momentum to neuroscience drug discovery, particularly in areas that are stalled on the concept of 'fixing the brain chemistry'. Optogenetics is beginning to translate and transit into drug discovery in several key domains, including target discovery, high-throughput screening and novel therapeutic approaches to disease states. Here, we discuss the exciting potential of optogenetic technologies to transform neuroscience drug discovery. PMID:26612666

  1. Hybrid organic inorganic materials: Layered hydroxy double salts intercalated with substituted thiophene monomers

    NASA Astrophysics Data System (ADS)

    Tronto, Jairo; Leroux, Fabrice; Dubois, Marc; Taviot-Gueho, Christine; Valim, João Barros

    2006-05-01

    The present paper describes the synthesis and characterization of Layered Hydroxy Double Salts (HDSs) containing substituted thiophene anions (2-thiophenecarboxylate, 3-thiophenecarboxylate, and 3-thiopheneacetate). The HDSs host was synthesized via hydrothermal method and the organic anions were incorporated between the sheets by anion-exchange reaction. The materials were characterized by powder X-ray diffraction (PXRD), thermal gravimetric (TG) analysis and electron spin resonance (ESR) spectroscopy. For the 2D-hybrid materials, the basal spacing is found to be consistent with the formation of bilayers of the intercalated organic monomers. For the hybrid material formed after intercalation of 3-thiopheneacetate anion, the ESR signals suggest that the monomers connect each other directly forming small oligomers, whereas this process is not occurring for the two other monomers presenting short alkyl chain. The TG analyses show different stages of thermal decomposition between HDSs host and 2D-hybrid materials, underlining the enhanced thermal stability of the hybrid assembly.

  2. Forces generated by cell intercalation tow epidermal sheets in mammalian tissue morphogenesis.

    PubMed

    Heller, Evan; Kumar, K Vijay; Grill, Stephan W; Fuchs, Elaine

    2014-03-31

    While gastrulation movements offer mechanistic paradigms for how collective cellular movements shape developing embryos, far less is known about coordinated cellular movements that occur later in development. Studying eyelid closure, we explore a case where an epithelium locally reshapes, expands, and moves over another epithelium. Live imaging, gene targeting, and cell-cycle inhibitors reveal that closure does not require overlying periderm, proliferation, or supracellular actin cable assembly. Laser ablation and quantitative analyses of tissue deformations further distinguish the mechanism from wound repair and dorsal closure. Rather, cell intercalations parallel to the tissue front locally compress it perpendicularly, pulling the surrounding epidermis along the closure axis. Functional analyses in vivo show that the mechanism requires localized myosin-IIA- and α5β1 integrin/fibronectin-mediated migration and E-cadherin downregulation likely stimulated by Wnt signaling. These studies uncover a mode of epithelial closure in which forces generated by cell intercalation are leveraged to tow the surrounding tissue. PMID:24697897

  3. Methotrexate intercalated layered double hydroxides with the mediation of surfactants: Mechanism exploration and bioassay study.

    PubMed

    Dai, Chao-Fan; Tian, De-Ying; Li, Shu-Ping; Li, Xiao-Dong

    2015-12-01

    Methotrexatum intercalated layered double hydroxides (MTX/LDHs) hybrids were synthesized by the co-precipitation method and three kinds of nonionic surfactants with different hydrocarbon chain lengths were used. The resulting hybrids were then characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). XRD and FTIR investigations manifest the successful intercalation of MTX anions into the interlayer of LDHs. TEM graphs indicate that the morphology of the hybrids changes with the variation of the chain length of the surfactants, i.e., the particles synthesized using polyethylene glycol (PEG-7) present regular disc morphology with good monodispersity, while samples with the mediation of alkyl polyglycoside (APG-14) are heavily aggregated and samples with the addition of polyvinylpyrrolidone (PVP-10) exhibit irregular branches. Furthermore, the release and bioassay experiments show that monodisperse MTX/LDHs present good controlled-release and are more efficient in the suppression of the tumor cells. PMID:26354264

  4. Fluorescent DNA Nanotags Featuring Covalently Attached Intercalating Dyes: Synthesis, Antibody Conjugation and Intracellular Imaging

    PubMed Central

    Stadler, Andrea L.; Santos, Junriz Delos; Stensrud, Elizabeth S.; Dembska, Anna; Silva, Gloria L.; Liu, Shengpeng; Shank, Nathaniel I.; Kunttas-Tatli, Ezgi; Sobers, Courtney J.; Gramlich, Philipp M. E.; Carell, Thomas; Peteanu, Linda A.; McCartney, Brooke M.; Armitage, Bruce A.

    2011-01-01

    We have synthesized fluorescent DNA duplexes featuring multiple thiazole orange (TO) intercalating dyes covalently attached to the DNA via a triazole linkage. The intercalating dyes stabilize the duplex against thermal denaturation and show bright fluorescence in the green. The emission color can be changed to orange or red by addition of energy-accepting Cy3 or Cy5 dyes attached covalently to the DNA duplex. The dye-modified DNA duplexes were then attached to a secondary antibody for intracellular fluorescence imaging of centrosomes in Drosophila embryos. Bright fluorescent foci were observed at the centrosomes in both the donor (TO) and acceptor (Cy5) channels, due to the fact that the energy transfer efficiency is moderate. Monitoring the Cy5 emission channel significantly minimized the background signal due to the large shift in emission wavelength allowed by energy transfer. PMID:21755981

  5. Three-dimensional metal-intercalated covalent organic frameworks for near-ambient energy storage

    PubMed Central

    Gao, Fei; Ding, Zijing; Meng, Sheng

    2013-01-01

    A new form of nanoporous material, metal intercalated covalent organic framework (MCOF) is proposed and its energy storage property revealed. Employing density functional and thermodynamical analysis, we find that stable, chemically active, porous materials could form by stacking covalent organic framework (COF) layers with metals as a gluing agent. Metal acts as active sites, while its aggregation is suppressed by a binding energy significantly larger than the corresponding cohesive energy of bulk metals. Two important parameters, metal binding and metal-metal separation, are tuned by selecting suitable building blocks and linkers when constructing COF layers. Systematic searches among a variety of elements and organic molecules identify Ca-intercalated COF with diphenylethyne units as optimal material for H2 storage, reaching a striking gravimetric density ~ 5 wt% at near-ambient conditions (300 K, 20 bar), in comparison to < 0.1 wt% for bare COF-1 under the same condition. PMID:23698018

  6. Mg intercalation in layered and spinel host crystal structures for Mg batteries.

    PubMed

    Emly, Alexandra; Van der Ven, Anton

    2015-05-01

    We investigate electrochemical properties of Mg in layered and spinel intercalation compounds from first-principles using TiS2 as a model system. Our calculations predict that Mg(x)TiS2 in both the layered and spinel crystal structures exhibits sloping voltage profiles with steps at stoichiometric compositions due to Mg-vacancy ordering. Mg ions are predicted to occupy the octahedral sites in both layered and spinel TiS2 with diffusion mediated by hops between octahedral sites that pass through adjacent tetrahedral sites. Predicted migration barriers are substantially higher than typical Li-migration barriers in intercalation compounds. The migration barriers are shown to be very sensitive to lattice parameters of the host crystal structure. We also discuss the possible role of rehybridization between the transition metal and the anion in affecting migration barriers. PMID:25905428

  7. Facile oxygen intercalation between full layer graphene and Ru(0001) under ambient conditions

    NASA Astrophysics Data System (ADS)

    Dong, Aiyi; Fu, Qiang; Wei, Mingming; Liu, Yun; Ning, Yanxiao; Yang, Fan; Bluhm, Hendrik; Bao, Xinhe

    2015-04-01

    Graphene coatings have been widely considered as protection layers on metal surfaces to prevent surface oxidation and corrosion in gaseous atmospheres. Here, using in-situ ambient pressure X-ray photoelectron spectroscopy we demonstrate that oxygen intercalation readily occurs at full monolayer graphene/Ru(0001) interfaces in 0.5 Torr O2 around 150 °C, resulting in decoupling of the graphene overlayer from the Ru surface and oxidation of the metal surface. Moreover, oxygen intercalation has been observed even upon illumination of the graphene/Ru(0001) surface with an infrared lamp in air. These results indicate that the stability of graphene/metal interfaces under ambient conditions should be taken into consideration for future applications.

  8. Poly(styrene)/oligo(fluorene)-intercalated fluoromica hybrids: synthesis, characterization and self-assembly

    PubMed Central

    Porzio, William; Scavia, Guido; Barba, Luisa; Arrighetti, Gianmichele; Ricci, Giovanni; Botta, Chiara

    2014-01-01

    Summary We report on the intercalation of a cationic fluorescent oligo(fluorene) in between the 2D interlayer region of a fluoromica type silicate. The formation of intercalated structures with different fluorophore contents is observed in powders by synchrotron radiation XRD. Successively, the hybrids are dispersed in poly(styrene) through in situ polymerization. Such a procedure allows us to synthesize the materials from solution, to achieve solid films, and to characterize them by optical and morphologic techniques. The polymeric films with homogeneous distribution of the hybrids exhibit ultraviolet–blue photoluminescence with a significantly enhanced photostability compared to the bare oligo(fluorene)s. Finally, under specific conditions, the polymer hybrid with higher oligo(fluorene) content spontaneously assembles into highly ordered microporous films. PMID:25671140

  9. Magnetic, luminescent Eu-doped Mg-Al layered double hydroxide and its intercalation for ibuprofen.

    PubMed

    Wang, Jun; Zhou, Jideng; Li, Zhanshuang; Song, Yanchao; Liu, Qi; Jiang, Zhaohua; Zhang, Milin

    2010-12-27

    A magnetic, luminescent Eu-doped Mg-Al layered double hydroxide with ibuprofen (IBU) intercalated in the gallery has been successfully prepared by a simple coprecipitation method. The physicochemical properties of the samples were well characterized by powder XRD, TEM, FTIR, TGA, inductively coupled plasma MS (ICP-MS), vibrating sample magnetometry (VSM), and fluorospectrophotometry. The results revealed that Fe(3)O(4) nanoparticles are coated on the surface of layered double hydroxides and the obtained (Mg(2)Al(0.95)Eu(0.05))(Fe)-(IBU) sample exhibits both superparamagnetic and luminescent properties, with a saturation magnetization value of 1.86 emu  g(-1) and a strong emission band at 610 nm, respectively. Additionally, it was found that the ibuprofen loading amount is about 31 % (w/w), and the intercalated ibuprofen possesses sustained release behavior when the magnetic, luminescent composite is immersed in simulated body fluid (SBF). PMID:21038324

  10. Left-right asymmetric cell intercalation drives directional collective cell movement in epithelial morphogenesis

    NASA Astrophysics Data System (ADS)

    Sato, Katsuhiko; Hiraiwa, Tetsuya; Maekawa, Emi; Isomura, Ayako; Shibata, Tatsuo; Kuranaga, Erina

    2015-12-01

    Morphogenetic epithelial movement occurs during embryogenesis and drives complex tissue formation. However, how epithelial cells coordinate their unidirectional movement while maintaining epithelial integrity is unclear. Here we propose a novel mechanism for collective epithelial cell movement based on Drosophila genitalia rotation, in which epithelial tissue rotates clockwise around the genitalia. We found that this cell movement occurs autonomously and requires myosin II. The moving cells exhibit repeated left-right-biased junction remodelling, while maintaining adhesion with their neighbours, in association with a polarized myosin II distribution. Reducing myosinID, known to cause counter-clockwise epithelial-tissue movement, reverses the myosin II distribution. Numerical simulations revealed that a left-right asymmetry in cell intercalation is sufficient to induce unidirectional cellular movement. The cellular movement direction is also associated with planar cell-shape chirality. These findings support a model in which left-right asymmetric cell intercalation within an epithelial sheet drives collective cellular movement in the same direction.

  11. In Situ Molecular Spectroscopic Evidence for CO2 Intercalation into Montmorillonite in Supercritical Carbon Dioxide

    SciTech Connect

    Loring, John S.; Schaef, Herbert T.; Turcu, Romulus VF; Thompson, Christopher J.; Miller, Quin RS; Martin, Paul F.; Hu, Jian Z.; Hoyt, David W.; Qafoku, Odeta; Ilton, Eugene S.; Felmy, Andrew R.; Rosso, Kevin M.

    2012-04-25

    The interaction of anhydrous supercritical CO2 (scCO2) with both kaolinite and ~1W (i.e. close to but less than one layer of hydration) calcium-saturated montmorillonite was investigated under conditions relevant to geologic carbon sequestration (50 °C and 90 bar). The CO2 molecular environment was probed in situ using a combination of three novel high-pressure techniques: X-ray diffraction, magic angle spinning nuclear magnetic resonance spectroscopy and attenuated total reflection infrared spectroscopy. We report the first direct evidence that the expansion of montmorillonite under scCO2 conditions is due to CO2 migration into the interlayer. Intercalated CO2 molecules are rotationally constrained and do not appear to react with waters to form bicarbonate or carbonic acid. In contrast, CO2 does not intercalate into kaolinite. The findings show that predicting the seal integrity of caprock will have complex dependence on clay mineralogy and hydration state.

  12. Intercalation of Coordinatively Unsaturated Fe(III) Ion within Interpenetrated Metal-Organic Framework MOF-5.

    PubMed

    Holmberg, Rebecca J; Burns, Thomas; Greer, Samuel M; Kobera, Libor; Stoian, Sebastian A; Korobkov, Ilia; Hill, Stephen; Bryce, David L; Woo, Tom K; Murugesu, Muralee

    2016-06-01

    Coordinatively unsaturated Fe(III) metal sites were successfully incorporated into the iconic MOF-5 framework. This new structure, Fe(III) -iMOF-5, is the first example of an interpenetrated MOF linked through intercalated metal ions. Structural characterization was performed with single-crystal and powder XRD, followed by extensive analysis by spectroscopic methods and solid-state NMR, which reveals the paramagnetic ion through its interaction with the framework. EPR and Mössbauer spectroscopy confirmed that the intercalated ions were indeed Fe(III) , whereas DFT calculations were employed to ascertain the unique pentacoordinate architecture around the Fe(III) ion. Interestingly, this is also the first crystallographic evidence of pentacoordinate Zn(II) within the MOF-5 SBU. This new MOF structure displays the potential for metal-site addition as a framework connector, thus creating further opportunity for the innovative development of new MOF materials. PMID:27061210

  13. Prediction of above 20 K superconductivity of blue phosphorus bilayer with metal intercalations

    NASA Astrophysics Data System (ADS)

    Zhang, Jun-Jie; Dong, Shuai

    2016-09-01

    First-principles calculations predicted monolayer blue phosphorus to be an alternative two-dimensional allotrope of phosphorus, like the recently discovered monolayer black phosphorus. Due to its unique crystalline and electronic structure, blue phosphorus may be a promising candidate as a BCS-superconductor after proper intercalation. In this study, using first-principles calculations, the favorable intercalation sites for some alkali metals and alkaline earths have been identified for Blue-P bilayer and the stacking configuration of bilayer is changed. Then the blue phosphorus bilayer transforms from a semiconductor to a metal due to the charge transfer from metal to phosphorus. Own to the strong electron–phonon coupling, isotropic superconducting state is induced and the calculated transition temperatures are 20.4, 20.1, and 14.4 K for Li-, Na-, and Mg-intercaltion, respectively, which is superior to other predicted or experimentally observed two-dimensional BCS-superconductors.

  14. Silicon layer intercalation of centimeter-scale, epitaxially grown monolayer graphene on Ru(0001)

    NASA Astrophysics Data System (ADS)

    Mao, Jinhai; Huang, Li; Pan, Yi; Gao, Min; He, Junfeng; Zhou, Haitao; Guo, Haiming; Tian, Yuan; Zou, Qiang; Zhang, Lizhi; Zhang, Haigang; Wang, Yeliang; Du, Shixuan; Zhou, Xingjiang; Castro Neto, A. H.; Gao, Hong-Jun

    2012-02-01

    We develop a strategy for graphene growth on Ru(0001) followed by silicon-layer intercalation that not only weakens the interaction of graphene with the metal substrate but also retains its superlative properties. This G/Si/Ru architecture, produced by silicon-layer intercalation approach (SIA), was characterized by scanning tunneling microscopy/spectroscopy and angle resolved electron photoemission spectroscopy. These experiments show high structural and electronic qualities of this new composite. The SIA allows for an atomic control of the distance between the graphene and the metal substrate that can be used as a top gate. Our results show potential for the next generation of graphene-based materials with tailored properties.

  15. Ultrafast Solvent-Assisted Sodium Ion Intercalation into Highly Crystalline Few-Layered Graphene.

    PubMed

    Cohn, Adam P; Share, Keith; Carter, Rachel; Oakes, Landon; Pint, Cary L

    2016-01-13

    A maximum sodium capacity of ∼35 mAh/g has hampered the use of crystalline carbon nanostructures for sodium ion battery anodes. We demonstrate that a diglyme solvent shell encapsulating a sodium ion acts as a "nonstick" coating to facilitate rapid ion insertion into crystalline few-layer graphene and bypass slow desolvation kinetics. This yields storage capacities above 150 mAh/g, cycling performance with negligible capacity fade over 8000 cycles, and ∼100 mAh/g capacities maintained at currents of 30 A/g (∼12 s charge). Raman spectroscopy elucidates the ordered, but nondestructive cointercalation mechanism that differs from desolvated ion intercalation processes. In situ Raman measurements identify the Na(+) staging sequence and isolates Fermi energies for the first and second stage ternary intercalation compounds at ∼0.8 eV and ∼1.2 eV. PMID:26618985

  16. A theoretical study of a carbon lattice system for lithium intercalated carbon anodes

    SciTech Connect

    Scanlon, L.G.; Storch, D.M.; Newton, J.H.; Sandi, G.

    1997-09-01

    A theoretical study was performed using computational chemistry to describe the intermolecular forces between graphite layers as well as spacing and conformation. It was found that electron correlation and a diffuse basis set were important for this calculation. In addition, the high reactivity of edge sites in lithium intercalated carbon anodes was also investigated. In this case, the reactive sites appear to strongly correlate with the relative distribution of the total atomic spin densities as well as total atomic charges. The spacing of graphite layers and lithium ion separation within an {open_quotes}approximated{close_quotes} lithium intercalated carbon anode was also investigated. The spacing of the carbon layers used in this investigation agrees most closely for that found in disordered carbon lattices.

  17. In situ molecular spectroscopic evidence for CO2 intercalation into montmorillonite in supercritical carbon dioxide.

    PubMed

    Loring, John S; Schaef, Herbert T; Turcu, Romulus V F; Thompson, Christopher J; Miller, Quin R S; Martin, Paul F; Hu, Jianzhi; Hoyt, David W; Qafoku, Odeta; Ilton, Eugene S; Felmy, Andrew R; Rosso, Kevin M

    2012-05-01

    The interaction of anhydrous supercritical CO(2) (scCO(2)) with both kaolinite and ~1W (i.e., close to but less than one layer of hydration) calcium-saturated montmorillonite was investigated under conditions relevant to geologic carbon sequestration (50 °C and 90 bar). The CO(2) molecular environment was probed in situ using a combination of three novel high-pressure techniques: X-ray diffraction, magic angle spinning nuclear magnetic resonance spectroscopy, and attenuated total reflection infrared spectroscopy. We report the first direct evidence that the expansion of montmorillonite under scCO(2) conditions is due to CO(2) migration into the interlayer. Intercalated CO(2) molecules are rotationally constrained and do not appear to react with waters to form bicarbonate or carbonic acid. In contrast, CO(2) does not intercalate into kaolinite. The findings show that predicting the seal integrity of caprock will have complex dependence on clay mineralogy and hydration state. PMID:22533894

  18. The effect of length and diameter on the resistivity of bromine intercalated graphite fibers

    NASA Technical Reports Server (NTRS)

    Gaier, James R.

    1989-01-01

    The resistivity of bromine intercalated graphite fibers has been shown to vary with both the diameter and the length of the fibers. This is due to bromine depletion from the fiber surface. Model calculations assuming a 1.0 micron bromine depletion zone for P-100, and 3.0 microns for vapor-grown graphite fibers fit the respective diameter dependence of their resistivities quite well. Length dependence data imply a bromine depletion zone along the length of P-100 fibers which is also a few microns, but that of vapor grown fibers appears to be as large as 300 microns. Despite these values, microfilaments, which are much smaller than the expected depletion zones, do form residual bromine intercalation compounds with resistivities about one-half of their pristine value.

  19. Confinement Effects on the Structure and Dynamics in Intercalated Polymer / Layered Silicates Nanohybrids

    SciTech Connect

    Chrissopoulou, K.; Afratis, A.; Fotiadou, S.; Frick, B.; Anastasiadis, S. H.

    2010-06-02

    The structure and dynamics of PEO/Na{sup +} MMT nanocomposites are investigated by XRD, DSC, and quasielastic neutron scattering (QENS). For concentrations up to 20 wt% the PEO chains within the galleries form either a single- or a double-layered structure of intercalated chains; at higher PEO content only double layers of intercalated PEO chains are formed within the 0.9 nm galleries. Moreover, it is only for polymer content above 70 wt% that peaks corresponding to crystalline PEO and DSC melting transition are observed, indicating that the confined chains remain liquid-like and only the excess polymer outside the completely full galleries can crystallize. QENS investigated the dynamics of PEO in bulk and in confinement. A jump of the bulk PEO dynamics at T{sub m} is observed whereas the dynamics of confined PEO shows only weak wavevector and temperature dependence and goes smoothly through the bulk T{sub m}.

  20. Synthesis and investigation of proton conductivity for intercalated kaolinite with 4-amidinopyridinium chloride

    NASA Astrophysics Data System (ADS)

    Ren, Li-Te; Li, Xiao-Pei; Liu, Jian-Lan; Ren, Xiao-Ming

    2015-12-01

    The proton-conducting materials have potential application in devices such as fuel cells. In this study, a mineral kaolinite-based proton conducting material, kaolinite-4-amidinopyridinium hydrochloride (K-4-APy-HCl), was synthesized by the intercalated compound kaolinite-4-amidinopyridine (K-4-APy) adsorbing volatilizing HCl. The thermogravimetric analysis (TG), powder X-ray diffraction (PXRD) and IR spectrum confirmed the HCl successfully inserting into the interlayer space of kaolinite and the 4-aminopyridine being protonated. The intercalation efficiency is estimated to be ca. 85.6%. With respect to K-4-APy, the interlayer space expends by 1.53 Å. The thermal decomposition mechanism was studied by PXRD and TG techniques. The K-4-APy-HCl shows proton conductivity with σ=3.379×10-8 S cm-1 at 373 K and Ea=1.159 eV in the anhydrous condition, which are comparable to MOFs-based proton conducting materials.

  1. Trafficking Highways to the Intercalated Disc: New Insights Unlocking the Specificity of Connexin 43 Localization

    PubMed Central

    Zhang, Shan-Shan; Shaw, Robin M.

    2016-01-01

    With each heartbeat, billions of cardiomyocytes work in concert to propagate the electrical excitation needed to effectively circulate blood. Regulated expression and timely delivery of connexin proteins to form gap junctions at the specialized cell – cell contact region, known as the intercalated disc, is essential to ventricular cardiomyocyte coupling. We focus this review on several regulatory mechanisms that have been recently found to govern the lifecycle of connexin 43 (Cx43), the short-lived and most abundantly expressed connexin in cardiac ventricular muscle. The Cx43 lifecycle begins with gene expression, followed by oligomerization into hexameric channels, and then cytoskeletal-based transport toward the disc region. Once delivered, hemichannels interact with resident disc proteins and are organized to effect intercellular coupling. We highlight recent studies exploring regulation of Cx43 localization to the intercalated disc, with emphasis on alternatively translated Cx43 isoforms and cytoskeletal transport machinery that together regulate Cx43 gap junction coupling between cardiomyocytes. PMID:24460200

  2. A naproxen complex of dysprosium intercalates into calf thymus DNA base pairs

    NASA Astrophysics Data System (ADS)

    Yang, Mengsi; Jin, Jianhua; Xu, Guiqing; Cui, Fengling; Luo, Hongxia

    2014-01-01

    The binding mode and mechanism of dysprosium-naproxen complex (Dy-NAP) with calf thymus deoxyribonucleic acid (ctDNA) were studied using UV-vis and fluorescence spectra in physiological buffer (pH 7.4). The results showed that more than one type of quenching process occurred and the binding mode between Dy-NAP with ctDNA might be intercalation. In addition, ionic strength, iodide quenching and fluorescence polarization experiments corroborated the intercalation binding mode between Dy-NAP and ctDNA. The calculated thermodynamic parameters ΔG, ΔH and ΔS at different temperature demonstrated that hydrophobic interaction force played a major role in the binding process.

  3. Intercalation of Varied Sulfonates into a Layered MOC: Confinement-Caused Tunable Luminescence and Novel Properties.

    PubMed

    Wen, Yuehong; Sheng, Tianlu; Zhu, Xiaoquan; Zhang, Hao; Zhuo, Chao; Hu, Shengmin; Cao, Wenhai; Wu, Xintao

    2016-04-01

    The pores/channels of porous 3D metal-organic frameworks (MOFs) have been widely applied to incorporate gas, solvent, or organic molecules. On the contrary, the utilization of the interlamellar void of layered metal-organic complexes (MOCs) remains underappreciated, although it is more flexible and available to accommodate molecules with different sizes. In this work, diverse sulfonates have been intercalated purposely into an identical layered MOC, which constructed various novel intercalation compounds possessing fluorescent, white-light emitting, photochromic, homochiral, or nonlinear optical (NLO) properties. With the help of single-crystal X-ray diffraction, their structures and the mutual interactions between the MOC host and the sulfonate guests were characterized. The properties of the guest molecules were tuned and meanwhile some new performances were generated after confining them into the interlayer region. Such a hybrid approach provides an efficient strategy to design and prepare multifunctional materials. PMID:26919304

  4. Transport and thermoelectric properties in Copper intercalated TiS2 chalcogenide

    NASA Astrophysics Data System (ADS)

    Guilmeau, E.; Bréard, Y.; Maignan, A.

    2011-08-01

    We report on the thermoelectric properties of CuxTiS2 bulk compounds. Copper cations have been intercalated into the layered chalcogenide TiS2 by spark plasma sintering. X-ray diffraction analysis coupled to transmission electron microscopy shows that the lattice constant c expands linearly as the Cu content x increases. The Cu-intercalation into TiS2 leads to substantial decrease in both electrical resistivity and lattice thermal conductivity as compared to those of pristine TiS2. The figure of merit, ZT, is increased up to 0.45 at 800 K for x = 0.02. The power factor, PF, reaches 1.7 mW/mK2 in TiS2 at 325 K.

  5. Transport and thermoelectric properties in Copper intercalated TiS{sub 2} chalcogenide

    SciTech Connect

    Guilmeau, E.; Breard, Y.; Maignan, A.

    2011-08-01

    We report on the thermoelectric properties of Cu{sub x}TiS{sub 2} bulk compounds. Copper cations have been intercalated into the layered chalcogenide TiS{sub 2} by spark plasma sintering. X-ray diffraction analysis coupled to transmission electron microscopy shows that the lattice constant c expands linearly as the Cu content x increases. The Cu-intercalation into TiS{sub 2} leads to substantial decrease in both electrical resistivity and lattice thermal conductivity as compared to those of pristine TiS{sub 2}. The figure of merit, ZT, is increased up to 0.45 at 800 K for x = 0.02. The power factor, PF, reaches 1.7 mW/mK{sup 2} in TiS{sub 2} at 325 K.

  6. DNA intercalation, topoisomerase II inhibition and cytotoxic activity of the plant alkaloid neocryptolepine.

    PubMed

    Bailly, C; Laine, W; Baldeyrou, B; De Pauw-Gillet, M C; Colson, P; Houssier, C; Cimanga, K; Van Miert, S; Vlietinck, A J; Pieters, L

    2000-06-01

    Cryptolepine and neocryptolepine are two indoloquinoline alkaloids isolated from the roots of the African plant Cryptolepis sanguinolenta. Both drugs have revealed antibacterial and antiparasitic activities and are strongly cytotoxic to tumour cells. We have recently shown that cryptolepine can intercalate into DNA and stimulates DNA cleavage by human topoisomerase II. In this study, we have investigated the mechanism of action and cytotoxicity of neocryptolepine, which differs from the parent isomer only by the orientation of the indole unit with respect to the quinoline moiety. The biochemical and physicochemical results presented here indicate that neocryptolepine also intercalates into DNA, preferentially at GC-rich sequences, but exhibits a reduced affinity for DNA compared with cryptolepine. The two alkaloids interfere with the catalytic activity of human topoisomerase II but the poisoning activity is slightly more pronounced with cryptolepine than with its isomer. The data provide a molecular basis to account for the reduced cytotoxicity of neocryptolepine compared with the parent drug. PMID:11049087

  7. Probing the recognition surface of a DNA triplex: Binding studies with intercalator-neomycin conjugates

    PubMed Central

    Xue, Liang; Xi, Hongjuan; Kumar, Sunil; Gray, David; Davis, Erik; Hamilton, Paris; Skirba, Michael; Arya, Dev P.

    2012-01-01

    Thermodynamic studies on the interactions between intercalator-neomycin conjugates and a DNA polynucleotide triplex [poly(dA)•2poly(dT)] were conducted. To draw a complete picture of such interactions, naphthalenedimide-neomycin (3) and anthraquinone-neomycin (4) were synthesized and used together with two other analogues, previously synthesized pyrene-neomycin (1) and BQQ-neomycin (2), in our investigations. A combination of experiments including UV denaturation, circular dichroism (CD) titration, differential scanning calorimetry (DSC), and isothermal titration calorimetry (ITC) revealed that all four conjugates (1–4) stabilized poly(dA)•2poly(dT) much greater than its parent compound, neomycin. UV melting experiments clearly showed that the temperature (Tm3→2) at which poly(dA)•2poly(dT) dissociated into poly(dA)•poly(dT) and poly(dT) increased dramatically (> 12 °C) in the presence of intercalator-neomycin (1–4) even at a very low concentration (2 µM). In contrast to intercalator-neomycin conjugates, the increment of Tm3→2 of poly(dA)•2poly(dT) induced by neomycin was negligible under the same conditions. The binding preference of intercalator-neomycin (1–4) to poly(dA)•2poly(dT) was also confirmed by competition dialysis and fluorescent intercalator displacement assay. Circular dichroism titration studies revealed that compound 1–4 had slightly larger binding site size (~7–7.5) with poly(dA)•2poly(dT) as compared to neomycin (~6.5). The thermodynamic parameters of these intercalator-neomycin conjugates with poly(dA)•2poly(dT) were derived from an integrated van’t Hoff equation using the Tm3→2 values, the binding site size numbers, and other parameters obtained from DSC and ITC. The binding affinity of all tested ligands with poly(dA)•2poly(dT) increased in the order neomycin < 1 < 3 < 4 < 2. Amongst them, the binding constant [(2.7 ± 0.3) × 108 M−1] of 2 with poly(dA)•2poly(dT) was the highest, almost 1000 fold more

  8. Photostability enhancement of azoic dyes adsorbed and intercalated into Mg-Al-layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Liu, Pengfei; Liu, Pei; Zhao, Kongcao; Li, Lei

    2015-11-01

    Two azoic dyes 4-aminoazobenzene-4-sulfonic (AS) and ethyl orange (EO) were adsorbed on or intercalated into Mg-Al-CO3 layered double hydroxide (LDH) for photostability enhancement. Fluorescence analysis results showed that the photostability of two dyes could be greatly improved after being adsorbed on the surface of Mg-Al-CO3-LDH matrix. Furthermore, photostability of adsorbed dyes was superior to that of intercalated dyes. It was suggested that AS or EO was adsorbed on LDHs surface through a strong chemisorption interaction, resulting in the enhancement of photostability. After the UV irradiation under N2 atmosphere, the absorbed dyes not only show great increase of fluorescence intensity but also exhibited high stability against UV irradiation. This work provides a feasible approach to enhance the photostability of azoic dye confined in an inorganic two-dimensional (2D) matrix via changing the microenvironment, which may be considered to be a promising method of improving photostability of solid fluorescent materials.

  9. Forces Generated by Cell Intercalation Tow Epidermal Sheets in Mammalian Tissue Morphogenesis

    PubMed Central

    Heller, Evan; Kumar, K. Vijay; Grill, Stephan W.; Fuchs, Elaine

    2014-01-01

    Summary While gastrulation movements offer mechanistic paradigms for how collective cellular movements shape developing embryos, far less is known about coordinated cellular movements that occur later in development. Studying eyelid closure, we explore a case where an epithelium locally reshapes, expands, and moves over another epithelium. Live imaging, gene targeting and cell cycle inhibitors reveal that closure does not require overlying periderm, proliferation or supracellular actin cable assembly. Laser ablation and quantitative analyses of tissue deformations further distinguish the mechanism from wound-repair and dorsal closure. Rather, cell intercalations parallel to the tissue front locally compress it perpendicularly, pulling the surrounding epidermis along the closure axis. Functional analyses in vivo show that the mechanism requires localized myosin-IIA and α5β1-fibronectin-mediated migration, and E-cadherin downregulation likely stimulated by Wnt signaling. These studies uncover a mode of epithelial closure in which forces generated by cell intercalation are leveraged to tow the surrounding tissue. PMID:24697897

  10. Indirect measurement of N-14 quadrupolar coupling for NH3 intercalated in potassium graphite

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Fronko, R. M.; Resing, H. A.

    1987-01-01

    A method for indirect measurement of the nuclear quadrupolar coupling was developed and applied to NH3 molecules in the graphite intercalation compound K(NH3)4.3C24, which has a layered structure with alternating carbon and intercalant layers. Three triplets were observed in the H-1 NMR spectra of the compound. The value of the N-14 quadrupolar coupling constant of NH3 (3.7 MHz), determined indirectly from the H-1 NMR spectra, was intermediate between the gas value of 4.1 MHz and the solid-state value of 3.2 MHz. The method was also used to deduce the (H-1)-(H-1) and (N-14)-(H-1) dipolar interactions, the H-1 chemical shifts, and the molecular orientations and motions of NH3.

  11. Transition on the entropic elasticity of DNA induced by intercalating molecules

    NASA Astrophysics Data System (ADS)

    Rocha, M. S.; Ferreira, M. C.; Mesquita, O. N.

    2007-09-01

    We use optical tweezers to perform stretching experiments on DNA molecules when interacting with the drugs daunomycin and ethidium bromide, which intercalate the DNA molecule. Our results show that the persistence length of the DNA-drug complexes increases strongly as the drug concentration increases up to some critical value. Above this critical value, the persistence length decreases abruptly and remains approximately constant for larger drug concentrations, at least in the concentration range used in our experiments. Measured intercalators critical concentrations for the persistence length transition coincide with the reported values for the helix-coil transition of DNA-drug complexes obtained from sedimentation experiments. The contour length of the molecules increases monotonically and saturates as the drug concentration increases. The neighbor exclusion model fits to our results for the total drug concentration as a function of the relative increase of the contour length.

  12. Predicting the voltage dependence of interfacial electrochemical processes at lithium-intercalated graphite edge planes.

    PubMed

    Leung, Kevin

    2015-01-21

    The applied potential governs lithium-intercalation and electrode passivation reactions in lithium ion batteries, but are challenging to calibrate in condensed phase DFT calculations. In this work, the "anode potential" of charge-neutral lithium-intercalated graphite (LiC6) with oxidized edge planes is computed as a function of Li-content (nLi) at edge planes, using ab initio molecular dynamics (AIMD), a previously introduced Li(+) transfer free energy method, and the experimental Li(+)/Li(s) value as reference. The voltage assignments are corroborated using explicit electron transfer from fluoroethylene carbonate radical anion markers. PF6(-) is shown to decompose electrochemically (i.e., not just thermally) at low potentials imposed by our voltage calibration technique. We demonstrate that excess electrons reside in localized states-in-the-gap in the organic carbonate liquid region, which is not semiconductor-like (band-state-like) as widely assumed in the literature. PMID:25438093

  13. Secondary ion mass spectroscopy depth profiling of hydrogen-intercalated graphene on SiC

    NASA Astrophysics Data System (ADS)

    Michałowski, Paweł Piotr; Kaszub, Wawrzyniec; Merkulov, Alexandre; Strupiński, Włodek

    2016-07-01

    For a better comprehension of hydrogen intercalation of graphene grown on a silicon carbide substrate, an advanced analytical technique is required. We report that with a carefully established measurement procedure it is possible to obtain a reliable and reproducible depth profile of bi-layer graphene (theoretical thickness of 0.69 nm) grown on the silicon carbide substrate by the Chemical Vapor Deposition method. Furthermore, we show that with depth resolution as good as 0.2 nm/decade, both hydrogen coming from the intercalation process and organic contamination can be precisely localized. As expected, hydrogen was found at the interface between graphene and the SiC substrate, while organic contamination was accumulated on the surface of graphene and did not penetrate into it. Such a precise measurement may prove to be invaluable for further characterization of 2D materials.

  14. Intercalation chemistry of cobalt and nickel dioxides: A facile route to new compounds containing organocations

    SciTech Connect

    Ramachandran, K.; Oriakhi, C.O.; Lerner, M.M.; Koch, V.R.

    1996-07-01

    A simple chemical method is reported for the intercalation of layered nickel or cobalt dioxide with organocations. Compounds containing anilinium, dodecyltrimethylammonium, octadecyltrimethylammonium, or distearyldimethylammonium cations are obtained by reaction of lithiated hosts with aqueous persulfate, followed by treatment with the desired organocation. Basal-repeat distances for the intercalated products indicate that the arrangements of organocations are similar to those seen with other layered hosts, with bilayers of alkylammonium ions, or a single layer of anilinium, in the pillared galleries. Thermogravimetric and elemental analyses are used to estimate compound stoichiometries, and indicate the partial exchange of organocation for lithium. The anilinium compound contains oligomeric cations, and is unstable when treated with polar solvents. Open circuit measurements indicate that the materials contain Co in an oxidation state of 3+ or higher.

  15. DNA Recognition by a Novel Bis-Intercalator, Potent Anticancer Drug XR5944

    PubMed Central

    Lin, Clement; Yang, Danzhou

    2016-01-01

    XR5944 is a potent anticancer drug with a novel DNA binding mode: DNA bis-intercalationg with major groove binding. XR5944 can bind the estrogen response element (ERE) sequence to block ER-ERE binding and inhibit ERα activities, which may be useful for overcoming drug resistance to currently available antiestrogen treatments. This review discusses the progress relating to the structure and function studies of specific DNA recognition of XR5944. The sites of intercalation within a native promoter sequence appear to be different from the ideal binding site and are context- and sequence- dependent. The structural information may provide insights for rational design of improved ERE-specific XR5944 derivatives, as well as of DNA bis-intercalators in general. PMID:25866279

  16. Three-dimensional metal-intercalated covalent organic frameworks for near-ambient energy storage

    NASA Astrophysics Data System (ADS)

    Gao, Fei; Ding, Zijing; Meng, Sheng

    2013-05-01

    A new form of nanoporous material, metal intercalated covalent organic framework (MCOF) is proposed and its energy storage property revealed. Employing density functional and thermodynamical analysis, we find that stable, chemically active, porous materials could form by stacking covalent organic framework (COF) layers with metals as a gluing agent. Metal acts as active sites, while its aggregation is suppressed by a binding energy significantly larger than the corresponding cohesive energy of bulk metals. Two important parameters, metal binding and metal-metal separation, are tuned by selecting suitable building blocks and linkers when constructing COF layers. Systematic searches among a variety of elements and organic molecules identify Ca-intercalated COF with diphenylethyne units as optimal material for H2 storage, reaching a striking gravimetric density ~ 5 wt% at near-ambient conditions (300 K, 20 bar), in comparison to < 0.1 wt% for bare COF-1 under the same condition.

  17. Discovery of cosmic rays

    NASA Astrophysics Data System (ADS)

    Carlson, Per

    2013-02-01

    The mysterious invisible radiation that ionized air was studied a century ago by many scientists. Finally, on 7 August 1912, Victor Hess in his seventh balloon flight that year, reached an altitude of about 5000 m. With his electroscopes on board the hydrogen-filled balloon he observed that the ionization instead of decreasing with altitude increased significantly. Hess had discovered cosmic rays, a discovery that gave him the 1936 Nobel Prize in physics. When research resumed after World War I focus was on understanding the nature of the cosmic radiation. Particles or radiation? Positive or negative? Electrons, positrons or protons? Progress came using new instruments like the Geiger-Muller tube and around 1940 it was clear that cosmic rays were mostly protons.

  18. Burkitt Lymphoma: beyond discoveries

    PubMed Central

    2013-01-01

    First described in 1958 in Uganda, Burkitt lymphoma (BL) attracted interest worldwide following reports of its uneven geographic distribution and rapidly fatal clinical course. Both suggested infectious etiology and curability. Seminal discoveries followed in quick succession. Viral etiology – due to Epstein-Barr virus (EBV) – was confirmed. Chromosomal translocations, involving cellular MYC, a protooncogene, were discovered, shown to be a hallmark of BL, and central to the genetic basis of cancer. Cure of BL using combination chemotherapy was demonstrated. Unfortunately, civil disturbance in Africa disrupted BL research and blunted its impact on education and oncology care in Africa. Important questions went unanswered. The risk of BL due to malaria or EBV was not quantified. Efforts to answer whether BL could be prevented – by preventing malaria or early EBV infection – were abandoned. The mechanism of malaria in BL is unknown. In Africa, BL remains mostly fatal and diagnosis is still made clinically. Unprecedented advances in molecular, genomics and proteomic technologies, promising to unlock mysteries of cancers, have re-awakened interest in BL. With return of stability to Africa, the unanswered questions about BL are re-attracting global interest. This interest now includes exploiting the knowledge gained about genetics, proteomics, and bioinformatics to enable the development of targeted less toxic treatment for BL; and simpler methods to diagnose BL with high accuracy and sensitivity. The articles in the Burkitt Lymphoma (BL): Beyond Discoveries in Infectious Agents and Cancer highlight BL as priority. Authors explore etiology, pathology, pathogenesis of BL, and whether knowledge gained in the studies of BL can catalyze sustainable cancer services in one of the world’s poorest served regions. PMID:24079372

  19. Multicolour photochromism of colloidal solutions of niobate nanosheets intercalated with several kinds of metal ions.

    PubMed

    Kamada, Kai; Tanaka, Yosuke; Tokunaga, Motoko; Ueda, Taro; Hyodo, Takeo; Shimizu, Yasuhiro

    2016-02-25

    Colourless and transparent colloidal solutions of niobate nanosheets intercalated with some kinds of metal ions (M-NNS, M: metal) showed quasi-reversible photochromism. Ultraviolet light irradiation of the solutions induced a change in color while maintaining the transparency, and the color change was dependent on the metal ions. The coloured solutions were bleached by exposure to an oxidizing atmosphere. This cycle could be repeated several times. PMID:26821602

  20. Preparation and lithium intercalation behavior of TiO{sub 2} in aqueous solutions

    SciTech Connect

    Li, Yunjiao Li, Lin; Chen, Lingpeng; Wang, Xuanyu; Xu, Cang

    2014-04-01

    Highlights: • The poor crystalline anatase phase or amorphous TiO{sub 2} was prepared by TiCl{sub 4} hydrolysis under different pH conditions. • Phase transition behavior and lithium intercalation ability of the obtained TiO{sub 2} were found to be related to TiO{sub 2} property. • The results indicate that TiO{sub 2} products obtained from TiCl{sub 4} hydrolysis at lower pH are favorable for lithium intercalation. - Abstract: The low crystalline or amorphous TiO{sub 2} was prepared by TiCl{sub 4} hydrolysis in aqueous solutions under different pH conditions at 45 °C. The products obtained at lower pH (1.23–3.10) appear to be nano-sized particles with poor crystalline anatase structure and an uniform particle size distribution, while the product prepared at pH 4.10 presents in a poor crystalline anatase structure and the regular morphology starts to disappear, and the products obtained at higher pH (>6.00) are amorphous and irregular morphology. The hydrolysis products obtained at pH 2.60 and 8.80 were heat-treated at 300, 400, 600, 700 and 800 °C for 3 h, respectively, to figure out the phase transition. The differences in phase transition process were observed, which verified the properties difference. The lithium intercalation abilities of the obtained TiO{sub 2} were studied. The results indicated that the TiO{sub 2} obtained at lower pH are more favorable for lithium intercalation and are better precursors.

  1. Intermolecular interactions between imidazole derivatives intercalated in layered solids. Substituent group effect

    SciTech Connect

    González, M.; Lemus-Santana, A.A.; Rodríguez-Hernández, J.; Aguirre-Velez, C.I.; Knobel, M.; Reguera, E.

    2013-08-15

    This study sheds light on the intermolecular interactions between imidazole derive molecules (2-methyl-imidazole, 2-ethyl-imidazole and benzimidazole) intercalated in T[Ni(CN){sub 4}] layers to form a solid of formula unit T(ImD){sub 2}[Ni(CN){sub 4}]. These hybrid inorganic–organic solids were prepared by soft chemical routes and their crystal structures solved and refined from X-ray powder diffraction data. The involved imidazole derivative molecules were found coordinated through the pyridinic N atom to the axial positions for the metal T in the T[Ni(CN){sub 4}] layer. In the interlayers region ligand molecules from neighboring layers remain stacked in a face-to-face configuration through dipole–dipole and quadrupole–quadrupole interactions. These intermolecular interactions show a pronounced dependence on the substituent group and are responsible for an ImD-pillaring concatenation of adjacent layers. This is supported by the structural information and the recorded magnetic data in the 2–300 K temperature range. The samples containing Co and Ni are characterized by presence of spin–orbit coupling and pronounced temperature dependence for the effective magnetic moment except for 2-ethyl-imidazole related to the local distortion for the metal coordination environment. For this last one ligand a weak ferromagnetic ordering ascribed to a super-exchange interaction between T metals from neighboring layers through the ligands π–π interaction was detected. - Graphical abstract: In the interlayers region imidazole derivative molecules are oriented according to their dipolar and quadrupolar interactions and minimizing the steric impediment. Highlights: • Imidazole derivatives intercalation compounds. • Intermolecular interaction between intercalated imidazole derivatives. • Hybrid inorganic–organic solids. • Pi–pi interactions and ferromagnetic coupling. • Dipolar and quadrupolar interactions between intercalated imidazole derivatives.

  2. Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO3 lattice

    NASA Astrophysics Data System (ADS)

    Timoshenko, Janis; Kuzmin, Alexei; Purans, Juris

    2016-05-01

    The influence of hydrogen intercalation on the local structure of rhenium trioxide is studied in-situ by the Re L3-edge EXAFS spectroscopy and analysed using a novel approach, based on the use of evolutionary algorithm and wavelet transform. The proposed method allows us to perform accurate EXAFS analysis within the multiple-scattering approach taking into account contributions from outer coordination shells and to access the information on correlations in atomic thermal motion.

  3. High performance Li-ion sulfur batteries enabled by intercalation chemistry.

    PubMed

    Lv, Dongping; Yan, Pengfei; Shao, Yuyan; Li, Qiuyan; Ferrara, Seth; Pan, Huilin; Graff, Gordon L; Polzin, Bryant; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie

    2015-09-11

    The unstable interface of lithium metal in high energy density Li sulfur (Li-S) batteries raises concerns of poor cycling, low efficiency and safety issues, which may be addressed by using intercalation types of anode. Herein, a new prototype of Li-ion sulfur battery with high performance has been demonstrated by coupling a graphite anode with a sulfur cathode (2 mA h cm(-2)) after successfully addressing the interface issue of graphite in an ether based electrolyte. PMID:26214797

  4. Direct Observation of Reversible Magnesium Ion Intercalation into a Spinel Oxide Host

    SciTech Connect

    Kim, Chunjoong; Phillips, Patrick J.; Key, Baris; Yi, Tanghong; Nordlund, Dennis; Yu, Young-Sang; Bayliss, Ryan D.; Han, Sang-Don; He, Meinan; Zhang, Zhengcheng; Burrell, Anthony K.; Klie, Robert F.; Cabana, Jordi

    2015-04-17

    Direct evidence of Mg2+ intercalation into a spinel-type Mn2O4 is provided. By com­bining tools with different sensitivities, from atomic-resolution X-ray spectro­scopy to bulk X-ray diffraction, it is demonstrated that Mg2+ reversibly occupies the tetrahedral sites of the spinel structure through the reduction of Mn when the electrochemical reaction is performed.

  5. Intercalation between antitumor anthracyclines and DNA as probed by resonance and surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Smulevich, G.; Mantini, A. R.; Casu, M.; Marzocchi, M. P.

    1991-05-01

    The antiturnor anthracyclincs, idarubicin (IDA ), adrianiycin (ADM), epirubicin (EPI), carminomycin (CAR) and 1 1-deoxycarminornycin (DCM), whose siructural formula includes a substituted hydroxyanthraquirionc chrornophore and a sugar residue, form intercalation complexes with DNA. The stacking interaction between the chromophore and the base-pairs of DNA gives rise to noticeable ciTects on resonance Raman (RR) and surface-enhanced resonance Raman (SERRS) scattering as well as on the absorption (ABS), its second derivative (D2) and fluorescence emission (FEM) spectra.

  6. The impact of DNA intercalators on DNA and DNA-processing enzymes elucidated through force-dependent binding kinetics

    PubMed Central

    Biebricher, Andreas S.; Heller, Iddo; Roijmans, Roel F. H.; Hoekstra, Tjalle P.; Peterman, Erwin J. G.; Wuite, Gijs J. L.

    2015-01-01

    DNA intercalators are widely used as fluorescent probes to visualize DNA and DNA transactions in vivo and in vitro. It is well known that they perturb DNA structure and stability, which can in turn influence DNA-processing by proteins. Here we elucidate this perturbation by combining single-dye fluorescence microscopy with force spectroscopy and measuring the kinetics of DNA intercalation by the mono- and bis-intercalating cyanine dyes SYTOX Orange, SYTOX Green, SYBR Gold, YO-PRO-1, YOYO-1 and POPO-3. We show that their DNA-binding affinity is mainly governed by a strongly tension-dependent dissociation rate. These rates can be tuned over a range of seven orders of magnitude by changing DNA tension, intercalating species and ionic strength. We show that optimizing these rates minimizes the impact of intercalators on strand separation and enzymatic activity. These new insights provide handles for the improved use of intercalators as DNA probes with minimal perturbation and maximal efficacy. PMID:26084388

  7. Optical properties of tungsten oxide thin films with protons intercalated during sputtering

    SciTech Connect

    Yamada, Y.; Tajima, K.; Bao, S.; Okada, M.; Yoshimura, K.; Roos, A.

    2008-03-15

    Tungsten oxide thin films with protons intercalated during deposition (H{sub x}WO{sub 3}) were prepared using reactive direct-current-magnetron sputtering in a gas mixture of argon, oxygen, and hydrogen. The as-deposited films fabricated under suitable conditions were colored due to the formation of tungsten bronze. The concentration of intercalated protons, given by the x values in H{sub x}WO{sub 3}, was evaluated by ejecting protons electrochemically from the films. The x value of the films prepared at a constant working pressure was found to be proportional to the hydrogen flow ratio during deposition. On the other hand, the x value of the films prepared at a constant hydrogen flow ratio decreased sharply with increasing working pressure during deposition. The dispersion of the extinction coefficient ({kappa}) of the films was estimated by analyzing the experimental spectra of {psi} and {delta} measured with spectroscopic ellipsometry using the model composed of a homogeneous tungsten bronze layer with an additional surface roughness layer. As a result of this analysis, the {kappa} value was found to increase sharply with the number of intercalated protons. There was a linear dependence between the {kappa} value and the x value for x<0.2, while for x>0.3, the absorption saturated. This indicates that it is possible to evaluate the x value of H{sub x}WO{sub 3} films using spectroscopic ellipsometry.

  8. Structural study and crystal chemistry of the first stage calcium graphite intercalation compound

    SciTech Connect

    Emery, Nicolas; Herold, Claire . E-mail: Claire.Herold@lcsm.uhp-nancy.fr; Lagrange, Philippe

    2005-09-15

    A novel and efficient synthesis method concerning the preparation of the first stage calcium graphite intercalation compound is provided. It makes use of a reaction between liquid metallic alloy and pyrolytic graphite. From now on it is especially easy to obtain bulk CaC{sub 6} samples. Thanks to such samples, it was possible to study in detail the crystal structure of this binary intercalation compound. It has been entirely specified, so that we know that CaC{sub 6} crystal is rhombohedral and belongs to the R3-bar m space group with the following parameters: a=517pm and {alpha}=49.55 deg. The elemental unit cell contains one calcium atom and six carbon atoms. In this paper, we show also how the various MC{sub 6} structures evolve according to the size of the intercalated element and to the bond nature that appears in the final compound. CaC{sub 6} is unique, since all the other MC{sub 6} compounds exhibit a hexagonal symmetry.

  9. Intercalation of organic molecules in 2D copper (II) nitroprusside: Intermolecular interactions and magnetic properties

    NASA Astrophysics Data System (ADS)

    Osiry, H.; Cano, A.; Lemus-Santana, A. A.; Rodríguez, A.; Carbonio, R. E.; Reguera, E.

    2015-10-01

    This contribution discusses the intercalation of imidazole and its 2-ethyl derivative, and pyridine in 2D copper nitroprusside. In the interlayer region, neighboring molecules remain interacting throu gh their dipole and quadrupole moments, which supports the solid 3D crystal structure. The crystal structure of this series of intercalation compounds was solved and refined from powder X-ray diffraction patterns complemented with spectroscopic information. The intermolecular interactions were studied from the refined crystal structures and low temperature magnetic measurements. Due to strong attractive forces between neighboring molecules, the resulting π-π cloud overlapping enables the ferromagnetic coupling between metal centers on neighboring layers, which was actually observed for the solids containing imidazole and pyridine as intercalated molecules. For these two solids, the magnetic data were properly described with a model of six neighbors. For the solid containing 2-ethylimidazole and for 2D copper nitroprusside, a model of four neighbors in a plane is sufficient to obtain a reliable data fitting.

  10. Magnetic properties and surface morphology of layered In2Se3 crystals intercalated with cobalt

    NASA Astrophysics Data System (ADS)

    Bakhtinov, A. P.; Boledzyuk, V. B.; Kovalyuk, Z. D.; Kudrynskyi, Z. R.; Lytvyn, O. S.; Shevchenko, A. D.

    2013-06-01

    The magnetic properties of layered Co x In2Se3 crystals electrochemically intercalated with cobalt in an external magnetic field and without a magnetic field and the morphology of the van der Waals surfaces of layers of these crystals have been investigated. It has been found that the ferromagnetic ordering at room temperature is observed only for Co x In2Se3 crystals intercalated in an external magnetic field. These crystals are nanocomposite materials that consist of a layered matrix and arrays of nanorings and nanowires formed from Co nanocrystals on the van der Waals surfaces of the In2Se3 layers. Cobalt nanocrystals in Co x In2Se3 crystals have a pyramidal equilibrium shape, which is characteristic of the face-centered cubic crystal structure, and their geometrical sizes are of the order of a few nanometers. The specific features of self-organization of cobalt magnetic nanostructures on the van der Waals surfaces of layered semiconductor crystals during their electrolytic intercalation in a magnetic field and the magnetic properties of these structures have been considered.

  11. Charge neutrality of quasi-free-standing monolayer graphene induced by the intercalated Sn layer

    NASA Astrophysics Data System (ADS)

    Kim, Hidong; Dugerjav, Otgonbayar; Lkhagvasuren, Altaibaatar; Seo, Jae M.

    2016-04-01

    It has been confirmed by angle-resolved photoemission spectroscopy that decoupled quasi-free-standing monolayer graphene (QFMLG), obtained by Sn intercalation between the ≤ft(6\\sqrt{3}× 6\\sqrt{3}\\right)R{{30}{^\\circ}} buffer layer and the 6H-SiC(0 0 0 1) substrate, is charge-neutral, i.e. the Dirac point matches with the Fermi level. By combined studies of scanning tunneling microscopy/spectroscopy and core-level/valence-band photoemission spectroscopy on this system, it has been found that the intercalated Sn atoms, bonding with the Si atoms of the top Si-C bilayer on the substrate comprise a hexagonal 10× 10 layer, which turns out to be metallic. Such a metallic character, which has never been found in intercalation using different elements, is a major cause of charge neutrality of QFMLG, since conduction electrons of the Sn layer compensate completely spontaneous polarization charges of 6H-SiC(0 0 0 1). This charge-neutral QFMLG is stable at a high temperature of 850 °C.

  12. Synthesis, characterization and cation adsorption of p-aminobenzoic acid intercalated on calcium phosphate

    SciTech Connect

    Silva, Camila F.N.; Lazarin, Angélica M.; Sernaglia, Rosana L.; Andreotti, Elza I.S.

    2012-06-15

    Graphical abstract: Scanning electron microscopy photographs of calcium phosphate (a) and intercalated with p-aminobenzoic acid (b). Highlights: ► Calcium phosphate was intercalated with p-aminobenzoic acid. ► Guest molecule contains nitrogen and oxygen atoms from amine and carboxylic groups. ► These basic centers are potentially useful for cation coordination in ethanol solution. ► Crystal morphology of compounds is lamellar, it agrees with expected structural characteristics. -- Abstract: Crystalline lamellar calcium phosphate retained 4-aminobenzoic acid inside its cavity without leaching. The intense infrared bands in the 1033 and 1010 cm{sup −1} interval confirmed the presence of the phosphonate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns, which gave basal distances of 712 and 1578 pm for the original and the intercalated compounds, respectively. Solid-state {sup 31}P nuclear magnetic resonance spectra presented only one peak for the phosphate groups attached to the main inorganic polymeric structure near −2.4 ppm. The adsorption isotherms from ethanol gave the maximum adsorption capacities of 6.44 and 3.34 mmol g{sup −1} for nickel and cobalt, respectively, which stability constant and distribution coefficient followed Co > Ni.

  13. Understanding sodium versus lithium intercalation potentials of electrode materials for alkali-ion batteries

    NASA Astrophysics Data System (ADS)

    Arroyo-de Dompablo, M. Elena

    2014-08-01

    Differences in average voltages for the alkali ion intercalation (Li, Na) in a variety of electrode materials are investigated. The average Li and Na insertion potentials in the cavities of ◻ReO3-perovskite, ramsdellite-◻Ti2O4, layered-◻2A2Ti3O7 (A = Li, Na) and NASICON-◻Na3Ti2(PO4)3 have been calculated by first principles calculations at the density functional theory level. The results identify the type of site occupied by the inserted ion as the relevant structural parameter. Occupation of large sites (c.n. = 12, 8) might yield Na insertion voltages higher than Li ones. On the other extreme, occupation of tetrahedral sites raises the Li insertion voltage as much as 0.8 V above the Na one. For octahedral sites the higher polarizing character of Li ions vs. Na ions acts as a key-factor to bring the Li intercalation voltage above that of Na intercalation.

  14. Low-Voltage Voltammetric Electrowetting of Graphite Surfaces by Ion Intercalation/Deintercalation.

    PubMed

    Zhang, Guohui; Walker, Marc; Unwin, Patrick R

    2016-08-01

    We demonstrate low-voltage electrowetting at the surface of freshly cleaved highly oriented pyrolytic graphite (HOPG). Using cyclic voltammetry (CV), electrowetting of a droplet of a sodium perchlorate solution is observed at moderately positive potentials on high-quality (low step edge coverage) HOPG, leading to significant changes in the contact angle and relative contact diameter that are comparable to the results of the widely studied electrowetting on dielectric (EWOD) system, but over a much lower voltage range. The electrowetting behavior is found to be reasonably fast, reversible, and repeatable for at least 20 cyclic scans (maximum tested). In contrast to classical electrowetting, e.g., EWOD, the electrowetting of the droplet on HOPG occurs with the intercalation/deintercalation of anions between the graphene layers of graphite, driven by the applied potential, observed in the CV response, and detected by X-ray photoelectron spectroscopy. The electrowetting behavior is strongly influenced by those factors that affect the extent of the intercalation/deintercalation of ions on graphite, such as potential range scan rate, potential polarity, quality of the HOPG substrate (step edge density and step height), and type of anion in the solution. In addition to perchlorate, sulfate salts also promote electrowetting, but some other salts do not. Our findings suggest a new mechanism for electrowetting based on ion intercalation, and the results are important to fundamental electrochemistry as well as to diversifying the means by which electrowetting can be controlled and applied. PMID:27406680

  15. Intercalating graphene with clusters of Fe3O4 nanocrystals for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Ke, Qingqing; Tang, Chunhua; Liu, Yanqiong; Liu, Huajun; Wang, John

    2014-04-01

    A hierarchical nanostructure consisting of graphene sheets intercalated by clusters of Fe3O4 nanocystals is developed for high-performance supercapacitor electrode. Here we show that the negatively charged graphene oxide (GO) and positively charged Fe3O4 clusters enable a strong electrostatic interaction, generating a hierarchical 3D nanostructure, which gives rise to the intercalated composites through a rational hydrothermal process. The electrocapacitive behavior of the resultant composites is systematically investigated by cyclic voltammeter and galvanostatic charge-discharge techniques, where a positive synergistic effect between graphene and Fe3O4 clusters is identified. A maximum specific capacitance of 169 F g-1 is achieved in the Fe3O4 clusters decorated with effectively reduced graphene oxide (Fe3O4-rGO-12h), which is much higher than those of rGO (101 F g-1) and Fe3O4 (68 F g-1) at the current density of 1 Ag-1. Moreover, this intercalated hierarchical nanostructure demonstrates a good capacitance retention, retaining over 88% of the initial capacity after 1000 cycles.

  16. Spin polarized current injection through HgBr{sub 2} intercalated Bi2212 intrinsic Josephson junctions.

    SciTech Connect

    Ozyuzer, L.; Kurter, C.; Ozdemir, M.; Zasadzinski, J. F.; Gray, K. E.; Hinks, D. G.

    2007-06-01

    To investigate the effect of polarized current on tunneling characteristics of intrinsic Josephson junctions (IJJs), spin-polarized and spin-degenerate current have been injected through the c-axis of HgBr{sub 2} intercalated Bi{sub 2.1}Sr{sub 1.5}Ca{sub 1.4}Cu{sub 2}O{sub 8+delta} (Bi2212) single crystals on which 10 times 10 mum{sup 2} mesas have been fabricated. These two spin conditions are achieved by depositing either Au (15 nm)/Co (80 nm)/Au (156 nm) multilayers or single Au film on HgBr{sub 2} intercalated Bi2212 with T{sub c} = 74 K followed by photolithography and Ar ion beam etching. The I-V characteristics have been measured with and without a magnetic field parallel to c-axis at 4.2 K. A fine, soft Au wire is used to make a gentle mechanical contact on the top of a particular mesa in the array. Tunneling conductance characteristics were obtained and the magnetic field dependence of sumgap voltage peaks was investigated. These peaks do not change in position with increasing magnetic field for both contact configurations. In addition, the temperature dependence of tunneling characteristics of the IJJs are obtained and existence of pseudogap feature is observed above T{sub c} for HgBr{sub 2} intercalated Bi2212.

  17. Synthesis of nanoporous graphite-derived carbon-silica composites by a mechanochemical intercalation approach.

    PubMed

    Chu, Y-H; Wang, Z-M; Yamagishi, M; Kanoh, H; Hirotsu, T; Zhang, Y-X

    2005-03-15

    A mechanochemical intercalation approach which applies a simple mechanical milling to induce intercalation reaction was applied to introduce controlled amount of tetraethoxylsilane (TEOS) into surfactant-preexpanded graphite oxide, and the relationships between the intercalation structure, the porosities of the calcined products, and the Si addition were examined. It was found that a small added amount of TEOS produced a more expanded ordered layer structure with the interlayer distance and silicon content increasing with the amount of TEOS added, although a large amount of added TEOS easily induces layer delamination, resulting in a less ordered structure. The silica structure in the composite is changed from a disordered structure having enhanced bond strain to a condensed silica network when the amount of TEOS added increases. The porosities of the final calcined samples increase with the increase of silicon content but then decrease slightly after reaching a maximum where silicon content starts to become constant, indicating that both silicon content and the composition state of silica particles and carbon layers play important roles in porosity formation. PMID:15752051

  18. Effect of length of chopped pristine and intercalated graphite fibers on the resistivity of fiber networks

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Stahl, Mark

    1988-01-01

    Samples of Amoco P-100 fibers were chopped to lengths of 3.14, 2.53, 1.90, 1.27, 0.66 mm, or milled for 2 hours. The two-point resistivity of compacts of these fibers were measured as a function of pressure from 34 kPa to 143 MPa. Samples of each fiber length were intercalated with bromine at room temperature and similarly measured. The low pressure resistivity of the compacts decreased with increasing fiber length. Intercalation lowered the resistivity of each of the chopped length compacts, but raised the resistivity of the milled fiber compacts. Bulk resistivity of all samples decreased with increasing pressure at similar rates. Even though fiber volumes were as low as 5 percent, all measurements exhibited measurable resistivity. A greater change with pressure in the resistance was observed for shorter fibers than for longer, probably an indication of tighter fiber packing. Intercalation appeared to have no effect on the fiber to fiber contact resistance.

  19. Properties of novel CVD graphite fibers and their bromine intercalation compounds

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Lake, Max L.; Moinuddin, Alia; Marabito, Mark

    1991-01-01

    A hybrid fiber with a PAN core surrounded by a vapor grown carbon fiber (VGCF) sheath was fabricated using a proprietary process. The density, ultimate tensile strength, Young's modulus, and resistivity of pristine and bromine intercalated fibers made by this technique having diameters varying from 5 to 50 microns were compared with the values predicted from the rule of mixtures model. For both the pristine and intercalated fibers, the density, ultimate tensile strength, and Young's modulus of the fibers were lower than predicted, but the resistivity was measured to be consistent with predictions. The lower than theoretical mechanical properties may be evidence of a low density disordered interface between the core and the sheath which would lower the density and degrade the mechanical properties, but would leave the resistivity nearly unaffected. Intercalation had little if any effect on the ultimate tensile strength and Young's modulus, but raised the density by about 11 pct., and lowered the resistivity by an order of magnitude. The diameter dependence of the resistivity showed evidence of a depletion layer of the type found in VGCF.

  20. Magnetic ordering of nickel hydroxide layers 30 Å apart obtained by intercalating dodecyl sulfate

    NASA Astrophysics Data System (ADS)

    Seehra, M. S.; Singh, V.

    2013-09-01

    The nature of magnetic ordering in quasi-2D layered hydroxide of Ni (LH-Ni-DS) with hexagonal structure and synthesized by intercalating dodecyl sulfate (DS) ligand, (C12H25OSO3)-, between the layers using a hydrothermal technique is investigated. The observation of (00l) peaks up to l = 8 in x-ray diffraction on the sample yields an interlayer spacing c ≃ 30.5 Å and a crystallite size ≃ 16 nm. Assignment of the lines observed in the FTIR spectra to the various groups of the DS ligand confirms the intercalation. From the analysis of detailed investigations of the temperature dependence of the magnetization M at different magnetic fields, ac susceptibilities at frequencies from 0.1 to 1 kHz, and electron magnetic resonance spectra at 9.28 GHz, it is concluded that LH-Ni-DS orders ferromagnetically at TC ≃ 23 K. This TC is about 45% higher than TC ≃ 16 K reported for LH-Ni-Ac with c ≃ 8.6 Å obtained by intercalating an acetate ligand between the layers. The roles of the interlayer dipolar interaction, magnetic anisotropy and exchange interactions in determining TC in LH-Ni-L systems for several ligands L yielding different c-axes are discussed.

  1. Interplay between intercalated oxygen superstructures and monolayer h -BN on Cu(100)

    DOE PAGESBeta

    Ma, Chuanxu; Park, Jewook; Liu, Lei; Kim, Yong-Sung; Yoon, Mina; Baddorf, Arthur P.; Gu, Gong; Li, An-Ping

    2016-08-18

    The confinement effect of intercalated atoms in van der Waals heterostructures can lead to interesting interactions between the confined atoms or molecules and the overlaying two-dimensional (2D) materials. In this paper, we report the formation of ordered Cu(100) p(2×2) oxygen superstructures by oxygen intercalation under the monolayer hexagonal boron nitride (h-BN) on Cu after annealing. By using scanning tunneling microscopy and x-ray photoelectron spectroscopy, we identify the superstructure and reveal its roles in passivating the exposed Cu surfaces, decoupling h-BN and Cu, and disintegrating h-BN monolayers. The oxygen superstructure appears as a 2D pattern on the exposed Cu surface ormore » quasi-1D stripes of paired oxygen intercalated in the interface of h-BN and Cu predominantly oriented along the moiré modulations. The oxygen superstructure is shown to etch the overlaying h-BN monolayer in a thermal annealing process. After extended annealing, the h-BN monolayer disintegrates into nanoislands with zigzag edges. Finally, we discuss the implications of these findings on the stability and oxidation resistance of h-BN and relate them to challenges in process integration and 2D heterostructures.« less

  2. Properties of hybrid CVD/PAN graphite fibers and their bromine intercalation compounds

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Lake, Max L.; Moinuddin, Alia; Marabito, Mark

    1992-01-01

    A hybrid fiber with a PAN core surrounded by a vapor grown carbon fiber (VGCF) sheath was fabricated using a proprietary process. The density, ultimate tensile strength, Young's modulus, and resistivity of pristine and bromine intercalated fibers made by this technique having diameters varying from 5 to 50 microns were compared with the values predicted from the rule of mixtures model. For both the pristine and intercalated fibers, the density, ultimate tensile strength, and Young's modulus of the fibers were lower than predicted, but the resistivity was measured to be consistent with predictions. The lower than theoretical mechanical properties may be evidence of a low density disordered interface between the core and the sheath which would lower the density and degrade the mechanical properties, but would leave the resistivity nearly unaffected. Intercalation had little if any effect on the ultimate tensile strength and Young's modulus, but raised the density by about 11 pct., and lowered the resistivity by an order of magnitude. The diameter dependence of the resistivity showed evidence of a depletion layer of the type found in VGCF.

  3. Effect of Temperature on the Local Structure of Kaolinite Intercalated with Potassium Acetate

    SciTech Connect

    White, Claire E.; Provis, John L.; Gordon, Laura E.; Riley, Daniel P.; Proffen, Thomas; van Deventer, Jannie S.J.

    2011-09-06

    Kaolinite intercalated with potassium acetate is of great interest in the areas of environmental remediation and industrial application; however, its exact atomic structure and the changes which occur when heated have remained largely elusive. Here, neutron pair distribution function analysis is used to investigate the local structural characteristics of this complex material, revealing that hydrated potassium acetate exists as a single layer in the interlamellar spacing of kaolinite. Furthermore, the potassium ions within the intercalated complex are most likely associated with the resonance structure of the acetate molecules, and upon heating (and decomposition of the carbon containing molecules), these ions become strongly associated with the negative charge located on the oxygen atoms in the alumina layers of dehydroxylated kaolinite. Several possible orientations of hydrated potassium acetate within the interlamellar spacing of kaolinite have been proposed and investigated using density functional modeling, revealing the complex nature of this material. Nevertheless, this investigation has shown that the dehydroxylated form of the intercalated compound contains highly strained alumina and available alkali (potassium), making it a viable alternative to traditional aluminosilicates.

  4. Enhancement of Thermoelectric Properties of Molybdenum Diselenide Through Combined Mg Intercalation and Nb Doping

    NASA Astrophysics Data System (ADS)

    Ruan, Limin; Zhao, Huaizhou; Li, Dandan; Jin, Shifeng; Li, Shanming; Gu, Lin; Liang, Jingkui

    2016-06-01

    Thermoelectric properties of MoSe2.1 were enhanced through a combination of Mg intercalation and Nb doping. Magnesium intercalation simultaneously enhances the Seebeck coefficient and electrical conductivity, owing to a favorable modification of band structure upon Mg intercalation. And Nb substitution on the Mo site increases carrier concentration by two orders of magnitude, in addition to reducing the thermal conductivity of the lattice. With systematic study of the anisotropic thermal and electrical transport properties, an optimized ZT of 0.2 was achieved at 888 K for a Nb0.03 Mo0.97Se2.1Mg0.2 sample along its out-of-plane direction, far exceeding the ˜0.01 value for intrinsic MoSe2.1. While 2 dimensional (2D) transitional-metal dichalcogenides with layered structure have been extensively studied for the fields of ion batteries, optical and electronic devices, and so on, enhancement of thermoelectric properties for these intrinsic semiconductors has rarely been investigated.

  5. Involvement of apurinic sites in the synergistic action of alkylating and intercalating drugs in Escherichia coli.

    PubMed

    Malvy, C; Safraoui, H; Bloch, E; Bertrand, J R

    1988-03-01

    The toxicity of the intercalating compounds 9-aminoellipticine (9AE) and isopropyl-oxazolopyridocarbazole (Ipr-OPC) were studied. The inhibitory effect of non-toxic doses of 9AE, which incises DNA at apurinic (AP) sites, or Ipr-OPC, which does not cleave DNA at AP sites, with non-toxic doses of the alkylating agent dimethylsulphate (DMS) on the growth of Escherichia coli strain AB1157, is additive. The same result has been observed with an exonuclease III mutant which has only 10% of the AP endonuclease activity. However, 9AE or Ipr-OPC display a synergistic toxic effect with a DMS concentration which allows 20% of E. coli AB1157 survival. This synergy is increased for 9AE in the AP endonuclease mutant when compared to the wild-type strain. Under identical conditions 9AE and Ipr-OPC have no synergistic effect on a mutant deficient in the enzymes which generate AP sites. Therefore AP sites are involved in the synergistic toxicity of DMS and the studied intercalating agents. However, the precise role of the interaction of intercalating agents with AP sites, either without cleavage (type 1 compounds) or with cleavage (type 2 compounds), in the observed effect remains an open question. PMID:3284541

  6. Intercalation of amino acids and oligopeptides into Zn Al layered double hydroxide by coprecipitation reaction

    NASA Astrophysics Data System (ADS)

    Aisawa, Sumio; Sasaki, Shuji; Takahashi, Satoshi; Hirahara, Hidetoshi; Nakayama, Hirokazu; Narita, Eiichi

    2006-05-01

    The coprecipitation of amino acids and oligopeptides with the Zn Al LDH was investigated using phenylalanine (Phe), phenylalanyl-phenylalanine (Phe-Phe), glycyl-phenylalanine (Gly Phe), glycine (Gly), glycyl-glycine (Gly Gly), glycyl-glycyl-glycine (Gly Gly Gly) and N-(N-γ-glutamyl-cysteinyl)-glycine (GSH) as guest species. The coprecipitation behavior of amino acids and oligopeptides was found to be influenced by the solution pH and the kind of their side chain groups, and reached the maximum at pH 8 or 9. The basal spacing, d003, of the Phe, Phe-Phe and GSH/LDH was 1.81, 2.41 and 1.64 nm, supporting that guests were arranged vertical to the LDH basal layer. Acceding to the basal spacing of the Gly, Gly Gly and Gly Gly Gly/LDH (d003=0.84 0.88 nm), these guests were oriented horizontal to the LDH basal layer with the co-intercalated NO3-. Moreover, the amount of Phe-Phe, Gly Gly and Gly Gly Gly intercalated was almost the same as that of Phe and Gly despite increasing the number peptide bond and the molecular size. GSH was intercalated into the LDH interlayer space as GSH oxidized form with bridged LDH layers by their carboxylate groups.

  7. Effect of Non-ionic Surfactants and Its Role in K Intercalation in Electrolytic Manganese Dioxide

    NASA Astrophysics Data System (ADS)

    Biswal, Avijit; Tripathy, B. C.; Subbaiah, T.; Meyrick, D.; Ionescu, Mihail; Minakshi, Manickam

    2014-09-01

    The effect of non-ionic surface active agents (surfactants) Triton X-100 (TX-100) and Tween-20 (Tw-20) and their role in potassium intercalation in electrolytic manganese dioxide (EMD) produced from manganese cake has been investigated. Electrosynthesis of MnO2 in the absence or presence of surfactant was carried out from acidic MnSO4 solution obtained from manganese cake under optimized conditions. A range of characterization techniques, including field emission scanning electron microscopy, transmission electron microscopy (TEM), Rutherford back scattering (RBS), and BET surface area/porosity studies, was carried out to determine the structural and chemical characteristics of the EMD. Galvanostatic (discharge) and potentiostatic (cyclic voltammetric) studies were employed to evaluate the suitability of EMD in combination with KOH electrolyte for alkaline battery applications. The presence of surfactant played an important role in modifying the physicochemical properties of the EMD by increasing the surface area of the material and hence, enhancing its electrochemical performance. The TEM and RBS analyses of the discharged EMD (γ-MnO2) material showed clear evidence of potassium intercalation or at least the formation of a film on the MnO2 surface. The extent of intercalation was greater for EMD deposited in the presence of TX-100. Discharged MnO2 showed products of Mn2+ intermediates such as MnOOH and Mn3O4.

  8. Alkyl substitution effects on the intercalation of carcinogenic hydrocarbon and hydrocarbon metabolites into DNA

    SciTech Connect

    LeBreton, P.R.

    1986-05-01

    A large number of carcinogenic hydrocarbons and hydrocarbon metabolites intercalate into DNA with binding constants in terms of PO/sub 4//sup -/ concentration which lie in the range 10/sup 3/-10/sup 4/ M/sup -1/. These binding constants are similar to those associated with base stacking and hydrogen bonding interactions that occur naturally in DNA. Previous studies show that different metabolites derived from the same parent hydrocarbon exhibit different binding properties. In recent studies the authors have examined the effects of alkyl substitution on hydrocarbon binding to calf thymus DNA. Such groups can enhance or inhibit carcinogenic activity. Studies of 1-alkyl BP/sup +/ derivatives and of their 7,8-dihydrodiols indicate that the alkyl groups ethyl, isopropyl and t-butyl inhibit intercalation. Methyl groups can either inhibit or enhance intercalation into DNA. The binding constants of DMBA and BA are nearly the same. However, DMA, which is a ..pi.. electron model compound of the bay region diol epoxide of DMBA, binds 6.7 times better than anthracene. Similarly, highly carcinogenic 5-methylchyrsene binds to DNA 3.9 times better than chrysene. /sup +/Abbreviations: BP, benzo(a)pyrene; DMBA, 7,12-dimethylbenz(a)anthracene; BA, benz(a)anthracene DMA, 9,10-dimethylanthracene.

  9. Intercalation of methotrexatum into layered double hydroxides via exfoliation-reassembly process

    NASA Astrophysics Data System (ADS)

    Liu, Su-Qing; Li, Shu-Ping; Li, Xiao-Dong

    2015-03-01

    In this paper, the intercalation of methotrexatum (MTX) into layered double hydroxides (LDHs) via an exfoliation-reassembly process was reported and the resulting hybrids were then characterized by X-ray diffraction (XRD) patterns, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) patterns etc. In the synthesis procedure, LDHs particles were firstly delaminated into well-dispersed 2D nanosheets in formamide by ultrasonic treatment at room temperature, and then the resulting LDH nanosheets were reassembled in MTX solution to form MTX intercalated LDH (MTX/LDHs) hybrids. AFM images showed that during the exfoliation process a large part of LDHs particles were delaminated into single and double brucite layers. XRD patterns and FTIR investigations manifested the successful intercalation of MTX anions into LDHs interlayers for the final samples. It was also found out that the drug-loading capacity of the hybrids increased with the concentrations of MTX solutions, while the morphology became even aggregated. At last, the cell cytotoxicity of the hybrids was estimated by MTT assays on the human lung cancer cells (A549), and the results stated that MTX/LDHs hybrids had effective suppress role on the proliferation of cancer cells.

  10. Anion-intercalated layered double hydroxides modified test strips for detection of heavy metal ions.

    PubMed

    Wang, Nan; Sun, Jianchao; Fan, Hai; Ai, Shiyun

    2016-02-01

    In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)6(4-) or S(2-) anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10(-6) mol L(-1). Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields. PMID:26653453

  11. Preparation of graphite oxide by sodium cholate intercalation and sonication from Indonesian natural graphite

    NASA Astrophysics Data System (ADS)

    Panatarani, Camellia; Maulana, Ayu Oktama; Rianto, Anton; Joni, I. Made

    2016-02-01

    Graphite oxide is widely use in renewable energy application such as solar cells, fuel-cells, battery electrodes, catalyst support, etc. This paper reports the preparation of graphite oxide from Indonesian natural graphite by sodium cholate intercalation. The enrichment process of as received graphite with carbon content of 60% was carried out by using acid leaching (HF) method. The enrichment process successfully obtained graphite with carbon content 95.61% with contaminant minerals observed by EDS were magnesium and aluminum. Purified graphite was then intercalated by sodium cholate at various concentration and sonication time. The XRD results shows that preparation with concentration of sodium cholate 2 Wt.% and sonication 10 hours formed a peak characteristic of graphite oxide at 2θ=15°. In addition, the successful oxidation process designated by the C/O ratio of 15.75 observed from EDS and supported by the present of functional C-H and C-O obtained from the FTIR observation. It is concluded that the graphite oxide successfully prepared by intercalation using sodium cholate and sonication.

  12. The Molecular Basis of Radial Intercalation during Tissue Spreading in Early Development

    PubMed Central

    Szabó, András; Cobo, Isidoro; Omara, Sharif; McLachlan, Sophie; Keller, Ray; Mayor, Roberto

    2016-01-01

    Summary Radial intercalation is a fundamental process responsible for the thinning of multilayered tissues during large-scale morphogenesis; however, its molecular mechanism has remained elusive. Using amphibian epiboly, the thinning and spreading of the animal hemisphere during gastrulation, here we provide evidence that radial intercalation is driven by chemotaxis of cells toward the external layer of the tissue. This role of chemotaxis in tissue spreading and thinning is unlike its typical role associated with large-distance directional movement of cells. We identify the chemoattractant as the complement component C3a, a factor normally linked with the immune system. The mechanism is explored by computational modeling and tested in vivo, ex vivo, and in vitro. This mechanism is robust against fluctuations of chemoattractant levels and expression patterns and explains expansion during epiboly. This study provides insight into the fundamental process of radial intercalation and could be applied to a wide range of morphogenetic events. PMID:27165554

  13. Adsorption of the harmful hormone ethinyl estradiol inside hydrophobic cavities of CTA(+) intercalated montmorillonite.

    PubMed

    Burgos, A E; Ribeiro-Santos, Tatiana A; Lago, Rochel M

    2016-01-01

    Hydrophobic cavities produced by cetyltrimethylammonium cation (CTA(+)) exchanged and trapped in the interlayer space of montmorillonite were used to remove the harmful hormone contaminant ethinyl estradiol (EE2) from water. X-ray diffraction, thermogravimetry/derivative thermogravimetry, elemental analysis (carbon, hydrogen, nitrogen), Fourier transform infrared, scanning electron microscopy/energy dispersive spectroscopy, Brunauer-Emmett-Teller and contact angle analyses showed that the intercalation of 9, 16 and 34 wt% CTA(+) in the montmorillonite resulted in the d001 expansion from 1.37 to 1.58, 2.09 and 2.18 nm, respectively. EE2 adsorption experiments showed that the original clay montmorillonite does not remove EE2 from water whereas the intercalated composites showed high efficiency with adsorption capacities of 4.3, 8.8 and 7.3 mg g(-1) for M9CTA(+), M16CTA(+) and M34CTA(+), respectively. Moreover, experiments with montmorillonite simply impregnated with cetyltrimethylammonium bromide showed that the intercalation of CTA(+) to form the hydrophobic cavity is very important for the adsorption properties. Simple solvent extraction can be used to remove the adsorbed EE2 without significant loss of CTA(+), which allows the recovery and reuse of the adsorbent for at least five times. PMID:27508371

  14. Optimization of UV absorptivity of layered double hydroxide by intercalating organic UV-absorbent molecules.

    PubMed

    Mohsin, Sumaiyah Megat Nabil; Hussein, Mohd Zobir; Sarijo, Siti Halimah; Fakurazi, Sharida; Arulselvan, Palanisamy; Taufiq-Yap, Yun Hin

    2014-08-01

    Intercalation of Zn/Al layered double hydroxide (LDH) with benzophenone 9 (B9), a strong ultraviolet (UV) absorber, had been carried out by two different routes; co-precipitation and ion exchange method. Powder X-ray diffraction (PXRD) patterns of co-precipitated (ZB9C) and ion exchanged product (ZB91) showed basal spacing of 15.9 angstrom and 16.6 angstrom, respectively, as a result of the intercalation of B9 anions into the lamellae spaces of LDH. Intercalation was further confirmed by Fourier transform infrared spectra (FTIR), carbon, hydrogen, nitrogen and sulfur (CHNS) and thermogravimetric and differential thermogravimetric (TGA/DTG) studies. UV-vis absorption properties of the nanocomposite was investigated with diffuse reflectance UV-visible spectrometer and showed broader UV absorption range. Furthermore, stability of sunscreen molecules in LDH interlayer space was tested in deionized water, artificial sea water and skin pH condition to show slow deintercalation and high retention in host. Cytotoxicity study of the synthesized nanocomposites on human dermal fibroblast (HDF) cells shows no significant cytotoxicity after 24 h exposure for test concentrations up to 25 microg/mL. PMID:25016649

  15. Controlling the actuation properties of MXene paper electrodes upon cation intercalation

    DOE PAGESBeta

    Come, Jeremy E.; Black, Jennifer M.; Naguib, Michael; Lukatskaya, Maria R.; Beidaghi, Majid; Wesolowski, David J.; Gogotsi, Yury; Rondinone, Adam J.; Balke, Nina; Kalinin, Sergei V.

    2015-08-05

    Atomic force microscopy was used to monitor the macroscopic deformation in a delaminated Ti₃C₂ paper electrode in-situ, during charge/discharge in a variety of aqueous electrolytes to examine the effect of the cation intercalation on the electrochemical behavior and mechanical response. The results show a strong dependence of the electrode deformation on cation size and charge. The electrode undergoes a large contraction during Li⁺, Na⁺ or Mg²⁺ intercalation, differentiating the Ti₃C₂ paper from conventional electrodes where redox intercalation of ions (e.g. Li⁺) into the bulk phase (e.g. graphite, silicon) results in volumetric expansion. This feature may explain the excellent rate performancemore » and cyclability reported for MXenes. We also demonstrated that the variation of the electromechanical contraction can be easily adjusted by electrolyte exchange, and shows interesting characteristics for the design of actuators based on 2D metal carbides.« less

  16. Formation of mixed-layer structures in smectites intercalated with tryptone

    NASA Astrophysics Data System (ADS)

    Block, K. A.; Trusiak, A.; Steiner, J. C.; Katz, A.; Gottlieb, P.; Alimova, A.

    2012-12-01

    Stable clay-protein complexes are fundamental to studies of the critical zone, terrestrial ecosystems, pharmacology, and industrial applications such as bioremediation. Two sets of montmorillonite clays were purified and made homoionic for Na and Mg. Mg-montmorillonite and Na-montmorillonite were mixed with tryptone (casein digest) in a 9:1 and 18:1 clay:tryptone ratio, resulting in the formation of reversible intercalated structures. X-ray diffraction analysis of the protein-clay complexes produced profiles consisting of two peaks associated with the smectite 001 reflection and a related tryptone-packet peak similar to that produced by a mixed layer clay structure. Shifts in the 002, 003, and 004 diffraction maxima are attributed to disorder caused by the interaction with the protein. Line broadening in the smectite-tryptone XRD spectra is interpreted to be the result of interlayer absorption. Adsorption produces coherent crystalline packets of regularly interbedded tryptone and smectite platelets. SEM images reveal clay platelets with upwardly rolled edges that tend toward cylindrical structures with the production of occasional tubes in the smaller platelet size range as noted for organic compound-kaolinite intercalation reported by Fenoll Hach-Ali and Weiss (1969). Reference: Fenoll Hach-Ali, P.F., Weiss, A., 1969. Estudio de la reaccion de caolinita y N-metilform- amida. Quimica LXV, 769-790. Scanning electron micrograph of tryptone-intercalated clay platelets exhibiting rolled edge structure.

  17. Synthesis and reversible hydration behavior of the thiosulfate intercalated layered double hydroxide of Zn and Al

    SciTech Connect

    Radha, S.; Milius, Wolfgang; Breu, Josef; Kamath, P. Vishnu

    2013-08-15

    The thiosulfate-intercalated layered double hydroxide of Zn and Al undergoes reversible hydration with a variation in the relative humidity of the ambient. The hydrated and dehydrated phases, which represent the end members of the hydration cycle, both adopt the structure of the 3R{sub 1} polytype. In the intermediate range of relative humidity values (40–60%), the hydrated and dehydrated phases coexist. The end members of the hydration cycle adopt the structure of the same polytype, and vary only in their basal spacings. This points to the possibility that all the intermediate phases have a kinetic origin. - Graphical abstract: Basal spacing evolution of the thiosulfate ion intercalated [Zn–Al] LDH during one complete hydration–dehydration cycle as a function of relative humidity. Display Omitted - Highlights: • Thiosulfate intercalated [Zn–Al] LDHs were synthesized by co-precipitation. • The LDH exhibits reversible hydration with variation in humidity. • Both the end members of the hydration cycle adopt the same polytype structure. • The interstratified intermediates observed are kinetic in origin.

  18. Use of Propranolol-Magnesium Aluminium Silicate Intercalated Complexes as Drug Reservoirs in Polymeric Matrix Tablets

    PubMed Central

    Pongjanyakul, T.; Rojtanatanya, S.

    2012-01-01

    The objective of the present study was to investigate the use of propranolol–magnesium aluminium silicate intercalated complexes as drug reservoirs in hydroxypropylmethylcellulose tablets. The matrix tablets containing the complexes were prepared and characterised with respect to propranolol release and were subsequently compared with those loading propranolol or a propranolol–magnesium aluminium silicate physical mixture. Additionally, the effects of varying viscosity grades of hydroxypropyl methylcellulose, compression pressures and calcium acetate incorporation on the drug release characteristics of the complex-loaded tablets were also examined. The results showed that the complex-loaded tablets have higher tablet hardness than those containing propranolol or a physical mixture. The drug release from the complex-loaded tablets followed a zero-order release kinetic, whereas an anomalous transport was found in the propranolol or physical mixture tablets. The drug release rate of the complex tablet significantly decreased with increasing hydroxypropylmethylcellulose viscosity grade. Increase in the compression pressure caused a decrease in the drug release rate of the tablets. Furthermore, the incorporation of calcium ions could accelerate propranolol release, particularly in acidic medium, because calcium ions could be exchanged with propranolol molecules intercalated in the silicate layers of magnesium aluminium silicate. These findings suggest that propranolol-magnesium aluminium silicate intercalated complexes show strong potential for use as drug reservoirs in matrix tablets intended for modifying drug release. PMID:23626384

  19. Preparation of poly(aniline-co-o-anisidine)-intercalated mesostructured manganese oxide composites by exchange reaction

    SciTech Connect

    Wang Gengchao Yang Zhenyu; Li Xingwei; Li Chunzhong; Yuan Weikang

    2008-08-04

    Layered mesostructured manganese oxide (mesostructured MnO{sub 2}) was synthesized using manganese chloride and lithium hydroxide as the raw materials and cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. Poly(aniline-co-o-anisidine)-intercalated mesostructured MnO{sub 2} composites (P(An-co-oAs)/MnO{sub 2}) were synthesized in an organic solvent through the exchange reaction between the CTAB in MnO{sub 2} gallery and the P(An-co-oAs). The interlayer spacing (I{sub c} values) of mesostructured MnO{sub 2} enlarged from 2.52 to 4.41 nm as the added amount of P(An-co-oAs) increased from 0 to 0.5 g per 0.5 g of mesostructured MnO{sub 2}. The regularity of the layered structure of the composites was firstly decreased due to intercalation of low amounts of P(An-co-oAs). However, with increasing the intercalated amount of P(An-co-oAs) the layered structure of the composites becomes more regular. The electrical conductivity of the composites is 10{sup 2} to 10{sup 3} times higher than that of the mesostructured MnO{sub 2}.

  20. The Molecular Basis of Radial Intercalation during Tissue Spreading in Early Development.

    PubMed

    Szabó, András; Cobo, Isidoro; Omara, Sharif; McLachlan, Sophie; Keller, Ray; Mayor, Roberto

    2016-05-01

    Radial intercalation is a fundamental process responsible for the thinning of multilayered tissues during large-scale morphogenesis; however, its molecular mechanism has remained elusive. Using amphibian epiboly, the thinning and spreading of the animal hemisphere during gastrulation, here we provide evidence that radial intercalation is driven by chemotaxis of cells toward the external layer of the tissue. This role of chemotaxis in tissue spreading and thinning is unlike its typical role associated with large-distance directional movement of cells. We identify the chemoattractant as the complement component C3a, a factor normally linked with the immune system. The mechanism is explored by computational modeling and tested in vivo, ex vivo, and in vitro. This mechanism is robust against fluctuations of chemoattractant levels and expression patterns and explains expansion during epiboly. This study provides insight into the fundamental process of radial intercalation and could be applied to a wide range of morphogenetic events. PMID:27165554