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Sample records for enhances solution state

  1. Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates.

    PubMed

    Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram

    2016-08-01

    We demonstrate that local and long-range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the substrate with solution-state disentanglement and preaggregation of P3HT in a θ solvent, leading to a very significant enhancement of the field effect carrier mobility. The preaggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of preaggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of preaggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to unaggregated polymer chains in the same conditions. Additional measurements reveal the combined preaggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known preaggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties. PMID:27410517

  2. Innovative Solution to Video Enhancement

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Through a licensing agreement, Intergraph Government Solutions adapted a technology originally developed at NASA's Marshall Space Flight Center for enhanced video imaging by developing its Video Analyst(TM) System. Marshall's scientists developed the Video Image Stabilization and Registration (VISAR) technology to help FBI agents analyze video footage of the deadly 1996 Olympic Summer Games bombing in Atlanta, Georgia. VISAR technology enhanced nighttime videotapes made with hand-held camcorders, revealing important details about the explosion. Intergraph's Video Analyst System is a simple, effective, and affordable tool for video enhancement and analysis. The benefits associated with the Video Analyst System include support of full-resolution digital video, frame-by-frame analysis, and the ability to store analog video in digital format. Up to 12 hours of digital video can be stored and maintained for reliable footage analysis. The system also includes state-of-the-art features such as stabilization, image enhancement, and convolution to help improve the visibility of subjects in the video without altering underlying footage. Adaptable to many uses, Intergraph#s Video Analyst System meets the stringent demands of the law enforcement industry in the areas of surveillance, crime scene footage, sting operations, and dash-mounted video cameras.

  3. Enhanced safeguards via solution monitoring

    SciTech Connect

    Burr, T.; Wangen, L.

    1996-09-01

    Solution monitoring is defined as the essentially continuous monitoring of solution level, density, and temperature in all tanks in the process that contain, or could contain, safeguards-significant quantities of nuclear material. This report describes some of the enhancements that solution monitoring could make to international safeguards. The focus is on the quantifiable benefits of solution monitoring, but qualitatively, solution monitoring can be viewed as a form of surveillance. Quantitatively, solution monitoring can in some cases improve diversion detection probability. For example, the authors show that under certain assumptions, solution monitoring can be used to reduce the standard deviation of the annual material balance, {sigma}{sub MB}, from approximately 17 kg to approximately 4 kg. Such reduction in {sigma}{sub MB} will not always be possible, as they discuss. However, in all cases, solution monitoring would provide assurance that the measurement error models are adequate so that one has confidence in his estimate of {sigma}{sub MB}. Some of the results in this report were generated using data that were simulated with prototype solution monitoring software that they are developing. An accompanying document describes that software.

  4. Transition state structures in solution

    SciTech Connect

    Bertran, J.; Lluch, J. M.; Gonzalez-Lafont, A.; Dillet, V.; Perez, V.

    1995-04-05

    In the present paper the location of transition state structures for reactions in solution has been studied. Continuum model calculations have been carried out on the Friedel-Crafts alkylation reaction and a proton transfer through a water molecule between two oxygen atoms in formic acid. In this model the separation between the chemical system and the solvent has been introduced. On the other hand, the discrete Monte Carlo methodology has also been used to simulate the solvent effect on dissociative electron transfer processes. In this model, the hypothesis of separability is not assumed. Finally, the validity of both approaches is discussed.

  5. Transition state structures in solution

    NASA Astrophysics Data System (ADS)

    Bertrán, J.; Lluch, J. M.; Gonzàlez-Lafont, A.; Dillet, V.; Pérez, V.

    1995-04-01

    In the present paper the location of transition state structures for reactions in solution has been studied. Continuum model calculations have been carried out on the Friedel-Crafts alkylation reaction and a proton transfer through a water molecule between two oxygen atoms in formic acid. In this model the separation between the chemical system and the solvent has been introduced. On the other hand, the discrete Monte Carlo methodology has also been used to simulate the solvent effect on dissociative electron transfer processes. In this model, the hypothesis of separability is not assumed. Finally, the validity of both approaches is discussed.

  6. A new association state of solutes in nanoconfined aqueous solutions

    NASA Astrophysics Data System (ADS)

    Tu, YuSong; Zhao, Liang; Fang, HaiPing

    2016-11-01

    Recently, we have found a reversible transition between the dispersion and aggregation states of solute molecules in aqueous solutions confined in nanoscale geometry, where solutes exhibit distinct behavior in a new association state from that in the dispersion and aggregation states observed usually in macroscopic systems. However, it remains unknown whether this new association state of solute molecules found in nanoconfined systems would vanish with the system size increasing and approaching the macroscopic scale. Here, we achieve the phase diagram of solute association states by making the analyses of Gibbs free energy of solutes in nanoconfined aqueous solutions in detail. In the phase diagram, we observe a closed regime with a finite system size of nanoconfined aqueous solutions and a solute concentration range, only in which there exists the new association state of solutes with the reversible transition between the aggregation and dispersion states, and there indeed exists an upper limit of the system size for the new association state, around several tens nanometers. These findings regarding the intimate connection between the system size and the solute association behavior provides the comprehensive understanding of the association dynamics of solutes in nanoconfined environment.

  7. Effects of Electronic-State-Dependent Solute Polarizability: Application to Solute-Pump/Solvent-Probe Spectra.

    PubMed

    Sun, Xiang; Ladanyi, Branka M; Stratt, Richard M

    2015-07-23

    Experimental studies of solvation dynamics in liquids invariably ask how changing a solute from its electronic ground state to an electronically excited state affects a solution's dynamics. With traditional time-dependent-fluorescence experiments, that means looking for the dynamical consequences of the concomitant change in solute-solvent potential energy. But if one follows the shift in the dynamics through its effects on the macroscopic polarizability, as recent solute-pump/solvent-probe spectra do, there is another effect of the electronic excitation that should be considered: the jump in the solute's own polarizability. We examine the spectroscopic consequences of this solute polarizability change in the classic example of the solvation dye coumarin 153 dissolved in acetonitrile. After demonstrating that standard quantum chemical methods can be used to construct accurate multisite models for the polarizabilities of ground- and excited-state solvation dyes, we show via simulation that this polarizability change acts as a contrast agent, significantly enhancing the observable differences in optical-Kerr spectra between ground- and excited-state solutions. A comparison of our results with experimental solute-pump/solvent-probe spectra supports our interpretation and modeling of this spectroscopy. We predict, in particular, that solute-pump/solvent-probe spectra should be sensitive to changes in both the solvent dynamics near the solute and the electronic-state-dependence of the solute's own rotational dynamics. PMID:25299940

  8. Perspectives on DNP-enhanced NMR spectroscopy in solutions

    NASA Astrophysics Data System (ADS)

    van Bentum, Jan; van Meerten, Bas; Sharma, Manvendra; Kentgens, Arno

    2016-03-01

    More than 60 years after the seminal work of Albert Overhauser on dynamic nuclear polarization by dynamic cross relaxation of coupled electron-nuclear spin systems, the quest for sensitivity enhancement in NMR spectroscopy is as pressing as ever. In this contribution we will review the status and perspectives for dynamic nuclear polarization in the liquid state. An appealing approach seems to be the use of supercritical solvents that may allow an extension of the Overhauser mechanism towards common high magnetic fields. A complementary approach is the use of solid state DNP on frozen solutions, followed by a rapid dissolution or in-situ melting step and NMR detection with substantially enhanced polarization levels in the liquid state. We will review recent developments in the field and discuss perspectives for the near future.

  9. Metastable States of small-molecule solutions.

    PubMed

    He, Guangwen; Tan, Reginald B H; Kenis, Paul J A; Zukoski, Charles F

    2007-12-27

    Metastable states such as gels and glasses that are commonly seen in nanoparticle suspensions have found application in a wide range of products including toothpaste, hand cream, paints, and car tires. The equilibrium and metastable state behavior of nanoparticle suspensions are often described by simple fluid models where particles are treated as having hard cores and interacting with short-range attractions. Here we explore similar models to describe the presence of metastable states of small-molecule solutions. We have recently shown that the equilibrium solubilities of small hydrogen-bonding molecules and nanoparticles fall onto a corresponding-states solubility curve suggesting that with similar average strengths of attraction these molecules have similar solubilities. This observation implies that metastable states in small-molecule solutions may be found under conditions similar to those where metastable states are observed in nanoparticle and colloidal suspensions. Here we seek confirmation of this concept by exploring the existence of metastable states in solutions of small molecules.

  10. Fracture-Flow-Enhanced Solute Diffusion into Fractured Rock

    SciTech Connect

    Wu, Yu-Shu; Ye, Ming; Sudicky, E.A.

    2007-12-15

    We propose a new conceptual model of fracture-flow-enhanced matrix diffusion, which correlates with fracture-flow velocity, i.e., matrix diffusion enhancement induced by rapid fluid flow within fractures. According to the boundary-layer or film theory, fracture flow enhanced matrix diffusion may dominate mass-transfer processes at fracture-matrix interfaces, because rapid flow along fractures results in large velocity and concentration gradients at and near fracture-matrix interfaces, enhancing matrix diffusion at matrix surfaces. In this paper, we present a new formulation of the conceptual model for enhanced fracture-matrix diffusion, and its implementation is discussed using existing analytical solutions and numerical models. In addition, we use the enhanced matrix diffusion concept to analyze laboratory experimental results from nonreactive and reactive tracer breakthrough tests, in an effort to validate the new conceptual model.

  11. Robustness enhancement of neurocontroller and state estimator

    NASA Technical Reports Server (NTRS)

    Troudet, Terry

    1993-01-01

    The feasibility of enhancing neurocontrol robustness, through training of the neurocontroller and state estimator in the presence of system uncertainties, is investigated on the example of a multivariable aircraft control problem. The performance and robustness of the newly trained neurocontroller are compared to those for an existing neurocontrol design scheme. The newly designed dynamic neurocontroller exhibits a better trade-off between phase and gain stability margins, and it is significantly more robust to degradations of the plant dynamics.

  12. 44 CFR 201.5 - Enhanced State Mitigation Plans.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 44 Emergency Management and Assistance 1 2014-10-01 2014-10-01 false Enhanced State Mitigation..., DEPARTMENT OF HOMELAND SECURITY DISASTER ASSISTANCE MITIGATION PLANNING § 201.5 Enhanced State Mitigation Plans. (a) A State with a FEMA approved Enhanced State Mitigation Plan at the time of a...

  13. 44 CFR 201.5 - Enhanced State Mitigation Plans.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 44 Emergency Management and Assistance 1 2012-10-01 2011-10-01 true Enhanced State Mitigation..., DEPARTMENT OF HOMELAND SECURITY DISASTER ASSISTANCE MITIGATION PLANNING § 201.5 Enhanced State Mitigation Plans. (a) A State with a FEMA approved Enhanced State Mitigation Plan at the time of a...

  14. 44 CFR 201.5 - Enhanced State Mitigation Plans.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 44 Emergency Management and Assistance 1 2011-10-01 2011-10-01 false Enhanced State Mitigation..., DEPARTMENT OF HOMELAND SECURITY DISASTER ASSISTANCE MITIGATION PLANNING § 201.5 Enhanced State Mitigation Plans. (a) A State with a FEMA approved Enhanced State Mitigation Plan at the time of a...

  15. Contrast enhancing solution for use in confocal microscopy

    DOEpatents

    Tannous, Zeina; Torres, Abel; Gonzalez, Salvador

    2006-10-31

    A method of optically detecting a tumor during surgery. The method includes imaging at least one test point defined on the tumor using a first optical imaging system to provide a first tumor image. The method further includes excising a first predetermined layer of the tumor for forming an in-vivo defect area. A predetermined contrast enhancing solution is disposed on the in-vivo defect area, which is adapted to interact with at least one cell anomaly, such as basal cell carcinoma, located on the in-vivo defect area for optically enhancing the cell anomaly. Thereafter the defect area can be optically imaged to provide a clear and bright representation of the cell anomaly to aid a surgeon while surgically removing the cell anomaly.

  16. Enhanced removal of radioactive particles by fluorocarbon surfactant solutions

    SciTech Connect

    Kaiser, R.; Harling, O.K.

    1993-08-01

    The proposed research addressed the application of ESI`s particle removal process to the non-destructive decontamination of nuclear equipment. The cleaning medium used in this process is a solution of a high molecular weight fluorocarbon surfactant in an inert perfluorinated liquid which results in enhanced particle removal. The perfluorinated liquids of interest, which are recycled in the process, are nontoxic, nonflammable, and environmentally compatible, and do not present a hazard to the ozone layer. The information obtained in the Phase 1 program indicated that the proposed ESI process is technically effective and economically attractive. The fluorocarbon surfactant solutions used as working media in the ESI process survived exposure of up to 10 Mrad doses of gamma rays, and are considered sufficiently radiation resistant for the proposed process. Ultrasonic cleaning in perfluorinated surfactant solutions was found to be an effective method of removing radioactive iron (Fe 59) oxide particles from contaminated test pieces. Radioactive particles suspended in the process liquids could be quantitatively removed by filtration through a 0.1 um membrane filter. Projected economics indicate a pre-tax pay back time of 1 month for a commercial scale system.

  17. Enhancement of flagellated bacterial motility in polymer solutions

    NASA Astrophysics Data System (ADS)

    Zhang, Wenyu; Sha, Sha; Pelcovits, Robert; Tang, Jay

    2015-11-01

    Measurements of the swimming speed of many species of flagellated bacteria in polymer solutions have shown that with the addition of high molecular weight polymers, the speed initially increases as a function of the kinematic viscosity. It peaks at around 1.5-2 cP with typically 10-30% higher values than in cell media without added polymers (~ 1 cP). Past the peak, the average speed gradually decreases as the solution becomes more viscous. Swimming motility persists until solution viscosity reaches 5-10 cP. Models have been proposed to account for this behavior, and the magnitude of the peak becomes a crucial test of theoretical predictions. The status of the field is complicated in light of a recent report (Martinez et al., PNAS, 2014), stressing that low-molecular weight impurities account for the peaked speed-viscosity curves in some cases. We measured the swimming speed of a uni-flagellated bacterium, caulobacter crescentus, in solutions of a number of polymers of several different sizes. Our findings confirm the peaked speed-viscosity curve, only as the molecular weight of the flexible polymers used surpassed ~ 50,000 da. The threshold molecular weight required to augment swimming speed varies somewhat with the polymer species, but it generally corresponds to radius of gyration over tens of nanometers. This general feature is consistent with the model of Powers et al. (Physics of Fluid, 2009), predicting that nonlinear viscoelasticity of the fluid enhances swimming motility. Work Supported by the NSF Fluid Physics Program (Award number CBET 1438033).

  18. An Enhanced Artificial Bee Colony Algorithm with Solution Acceptance Rule and Probabilistic Multisearch.

    PubMed

    Yurtkuran, Alkın; Emel, Erdal

    2016-01-01

    The artificial bee colony (ABC) algorithm is a popular swarm based technique, which is inspired from the intelligent foraging behavior of honeybee swarms. This paper proposes a new variant of ABC algorithm, namely, enhanced ABC with solution acceptance rule and probabilistic multisearch (ABC-SA) to address global optimization problems. A new solution acceptance rule is proposed where, instead of greedy selection between old solution and new candidate solution, worse candidate solutions have a probability to be accepted. Additionally, the acceptance probability of worse candidates is nonlinearly decreased throughout the search process adaptively. Moreover, in order to improve the performance of the ABC and balance the intensification and diversification, a probabilistic multisearch strategy is presented. Three different search equations with distinctive characters are employed using predetermined search probabilities. By implementing a new solution acceptance rule and a probabilistic multisearch approach, the intensification and diversification performance of the ABC algorithm is improved. The proposed algorithm has been tested on well-known benchmark functions of varying dimensions by comparing against novel ABC variants, as well as several recent state-of-the-art algorithms. Computational results show that the proposed ABC-SA outperforms other ABC variants and is superior to state-of-the-art algorithms proposed in the literature. PMID:26819591

  19. An Enhanced Artificial Bee Colony Algorithm with Solution Acceptance Rule and Probabilistic Multisearch

    PubMed Central

    Yurtkuran, Alkın

    2016-01-01

    The artificial bee colony (ABC) algorithm is a popular swarm based technique, which is inspired from the intelligent foraging behavior of honeybee swarms. This paper proposes a new variant of ABC algorithm, namely, enhanced ABC with solution acceptance rule and probabilistic multisearch (ABC-SA) to address global optimization problems. A new solution acceptance rule is proposed where, instead of greedy selection between old solution and new candidate solution, worse candidate solutions have a probability to be accepted. Additionally, the acceptance probability of worse candidates is nonlinearly decreased throughout the search process adaptively. Moreover, in order to improve the performance of the ABC and balance the intensification and diversification, a probabilistic multisearch strategy is presented. Three different search equations with distinctive characters are employed using predetermined search probabilities. By implementing a new solution acceptance rule and a probabilistic multisearch approach, the intensification and diversification performance of the ABC algorithm is improved. The proposed algorithm has been tested on well-known benchmark functions of varying dimensions by comparing against novel ABC variants, as well as several recent state-of-the-art algorithms. Computational results show that the proposed ABC-SA outperforms other ABC variants and is superior to state-of-the-art algorithms proposed in the literature. PMID:26819591

  20. An Enhanced Artificial Bee Colony Algorithm with Solution Acceptance Rule and Probabilistic Multisearch.

    PubMed

    Yurtkuran, Alkın; Emel, Erdal

    2016-01-01

    The artificial bee colony (ABC) algorithm is a popular swarm based technique, which is inspired from the intelligent foraging behavior of honeybee swarms. This paper proposes a new variant of ABC algorithm, namely, enhanced ABC with solution acceptance rule and probabilistic multisearch (ABC-SA) to address global optimization problems. A new solution acceptance rule is proposed where, instead of greedy selection between old solution and new candidate solution, worse candidate solutions have a probability to be accepted. Additionally, the acceptance probability of worse candidates is nonlinearly decreased throughout the search process adaptively. Moreover, in order to improve the performance of the ABC and balance the intensification and diversification, a probabilistic multisearch strategy is presented. Three different search equations with distinctive characters are employed using predetermined search probabilities. By implementing a new solution acceptance rule and a probabilistic multisearch approach, the intensification and diversification performance of the ABC algorithm is improved. The proposed algorithm has been tested on well-known benchmark functions of varying dimensions by comparing against novel ABC variants, as well as several recent state-of-the-art algorithms. Computational results show that the proposed ABC-SA outperforms other ABC variants and is superior to state-of-the-art algorithms proposed in the literature.

  1. Intermediates in the cation reactions in solution probed by an in situ surface enhanced Raman scattering method

    NASA Astrophysics Data System (ADS)

    Tan, Chih-Shan; Chen, Hung-Ying; Chen, Hsueh-Szu; Gwo, Shangjr; Chen, Lih-Juann

    2015-09-01

    For chemical reactions in liquid state, such as catalysis, understanding of dynamical changes is conducive to practical applications. Solvation of copper salts in aqueous solution has implications for life, the environment, and industry. In an ongoing research, the question arises that why the color of aqueous CuCl2 solution changes with solution concentration? In this work, we have developed a convenient and efficient in situ surface enhanced Raman scattering technique to probe the presence of many intermediates, some of them are responsible for color change, in crystallization of aqueous copper chloride solution. The versatility of the novel technique was confirmed in the identification of five intermediates states in the transition from CdS to MoS2 nanowires in solution. The facile in situ method is expected to be widely applicable in probing intermediate states in a variety of chemical reactions in solution.

  2. Intermediates in the cation reactions in solution probed by an in situ surface enhanced Raman scattering method.

    PubMed

    Tan, Chih-Shan; Chen, Hung-Ying; Chen, Hsueh-Szu; Gwo, Shangjr; Chen, Lih-Juann

    2015-01-01

    For chemical reactions in liquid state, such as catalysis, understanding of dynamical changes is conducive to practical applications. Solvation of copper salts in aqueous solution has implications for life, the environment, and industry. In an ongoing research, the question arises that why the color of aqueous CuCl2 solution changes with solution concentration? In this work, we have developed a convenient and efficient in situ surface enhanced Raman scattering technique to probe the presence of many intermediates, some of them are responsible for color change, in crystallization of aqueous copper chloride solution. The versatility of the novel technique was confirmed in the identification of five intermediates states in the transition from CdS to MoS2 nanowires in solution. The facile in situ method is expected to be widely applicable in probing intermediate states in a variety of chemical reactions in solution. PMID:26333518

  3. Intermediates in the cation reactions in solution probed by an in situ surface enhanced Raman scattering method

    PubMed Central

    Tan, Chih-Shan; Chen, Hung-Ying; Chen, Hsueh-Szu; Gwo, Shangjr; Chen, Lih-Juann

    2015-01-01

    For chemical reactions in liquid state, such as catalysis, understanding of dynamical changes is conducive to practical applications. Solvation of copper salts in aqueous solution has implications for life, the environment, and industry. In an ongoing research, the question arises that why the color of aqueous CuCl2 solution changes with solution concentration? In this work, we have developed a convenient and efficient in situ surface enhanced Raman scattering technique to probe the presence of many intermediates, some of them are responsible for color change, in crystallization of aqueous copper chloride solution. The versatility of the novel technique was confirmed in the identification of five intermediates states in the transition from CdS to MoS2 nanowires in solution. The facile in situ method is expected to be widely applicable in probing intermediate states in a variety of chemical reactions in solution. PMID:26333518

  4. Enhanced Semiconductor Nanocrystal Conductance via Solution Grown Contacts

    SciTech Connect

    Sheldon, Matthew T.; Trudeau, Paul-Emile; Mokari, Taleb; Wang, Lin-Wang; Alivisatos, A. Paul

    2009-08-19

    We report a 100,000-fold increase in the conductance of individual CdSe nanorods when they are electrically contacted via direct solution phase growth of Au tips on the nanorod ends. Ensemble UV-Vis and X-Ray photoelectron spectroscopy indicate this enhancement does not result from alloying of the nanorod. Rather, low temperature tunneling and high temperature (250-400 K) thermionic emission across the junction at the Au contact reveal a 75percent lower interface barrier to conduction compared to a control sample. We correlate this barrier lowering with the electronic structure at the Au-CdSe interface. Our results emphasize the importance of nanocrystal surface structure for robust device performance and the advantage of this contact method.

  5. Matrix-enhanced secondary ion mass spectrometry: The Alchemist's solution?

    NASA Astrophysics Data System (ADS)

    Delcorte, Arnaud

    2006-07-01

    Because of the requirements of large molecule characterization and high-lateral resolution SIMS imaging, the possibility of improving molecular ion yields by the use of specific sample preparation procedures has recently generated a renewed interest in the static SIMS community. In comparison with polyatomic projectiles, however, signal enhancement by a matrix might appear to some as the alchemist's versus the scientist's solution to the current problems of organic SIMS. In this contribution, I would like to discuss critically the pros and cons of matrix-enhanced SIMS procedures, in the new framework that includes polyatomic ion bombardment. This discussion is based on a short review of the experimental and theoretical developments achieved in the last decade with respect to the three following approaches: (i) blending the analyte with a low-molecular weight organic matrix (MALDI-type preparation procedure); (ii) mixing alkali/noble metal salts with the analyte; (iii) evaporating a noble metal layer on the analyte sample surface (organic molecules, polymers).

  6. Microbially-enhanced redox solution reoxidation for sweetening sour natural gas

    SciTech Connect

    Rai, C.

    1995-06-01

    About twenty five percent of natural gas produced in the United States is sour containing significant volumes of hydrogen sulfide and other contaminants. Liquid redox processes remove hydrogen sulfide from natural gas. Aqueous solution of chelated ferric ions oxidize the hydrogen sulfide to elemental sulfur. The reduced iron chelate is then oxidized by contact with air and recycled. This requires expensive equipment for regeneration, costly chemicals and the process is usually energy intensive. Recent studies show that the ferric ion regeneration rates are substantially enhanced in presence of acidophilic bacteria. The specific objectives of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes utilizing biologically-enhanced reoxidation of the redox solutions used in these processes, such as LO-CAT II and SulFerox.

  7. Convergence to steady state of solutions of Burgers' equation

    NASA Technical Reports Server (NTRS)

    Kreiss, G.; Kreiss, H. O.

    1985-01-01

    Consider the initial boundary value problem for Burgers' equation. It is shown that its solutions converge, in time, to a unique steady state. The speed of the convergence depends on the boundary conditions and can be exponentially slow. Methods to speed up the rate of convergence are also discussed.

  8. A theoretical framework for modeling dilution enhancement of non-reactive solutes in heterogeneous porous media.

    PubMed

    de Barros, F P J; Fiori, A; Boso, F; Bellin, A

    2015-01-01

    Spatial heterogeneity of the hydraulic properties of geological porous formations leads to erratically shaped solute clouds, thus increasing the edge area of the solute body and augmenting the dilution rate. In this study, we provide a theoretical framework to quantify dilution of a non-reactive solute within a steady state flow as affected by the spatial variability of the hydraulic conductivity. Embracing the Lagrangian concentration framework, we obtain explicit semi-analytical expressions for the dilution index as a function of the structural parameters of the random hydraulic conductivity field, under the assumptions of uniform-in-the-average flow, small injection source and weak-to-mild heterogeneity. Results show how the dilution enhancement of the solute cloud is strongly dependent on both the statistical anisotropy ratio and the heterogeneity level of the porous medium. The explicit semi-analytical solution also captures the temporal evolution of the dilution rate; for the early- and late-time limits, the proposed solution recovers previous results from the literature, while at intermediate times it reflects the increasing interplay between large-scale advection and local-scale dispersion. The performance of the theoretical framework is verified with high resolution numerical results and successfully tested against the Cape Cod field data.

  9. Sargassum as a Natural Solution to Enhance Dune Plant Growth

    NASA Astrophysics Data System (ADS)

    Williams, Amy; Feagin, Rusty

    2010-11-01

    Many beach management practices focus on creating an attractive environment for tourists, but can detrimentally affect long-term dune integrity. One such practice is mechanical beach raking in which the wrack line is removed from the beach front. In Texas, Sargassum fluitans and natans, types of brown alga, are the main components of wrack and may provide a subsidy to the ecosystem. In this study, we used greenhouse studies to test the hypothesis that the addition of sargassum can increase soil nutrients and produce increased growth in dune plants. We also conducted an analysis of the nutrients in the sargassum to determine the mechanisms responsible for any growth enhancement. Panicum amarum showed significant enhancement of growth with the addition of sargassum, and while Helianthus debilis, Ipomoea stolonifera, Sporobolus virginicus, and Uniola paniculata responded slightly differently to the specific treatments, none were impaired by the addition of sargassum. In general, plants seemed to respond well to unwashed sargassum and multiple additions of sargassum, indicating that plants may have adapted to capitalize on the subsidy in its natural state directly from the ocean. For coastal managers, the use of sargassum as a fertilizer could be a positive, natural, and efficient method of dealing with the accumulation of wrack on the beach.

  10. Heat transfer enhancement accompanying Leidenfrost state suppression at ultrahigh temperatures.

    PubMed

    Shahriari, Arjang; Wurz, Jillian; Bahadur, Vaibhav

    2014-10-14

    The well-known Leidenfrost effect is the formation of a vapor layer between a liquid and an underlying hot surface. This insulating vapor layer severely degrades heat transfer and results in surface dryout. We measure the heat transfer enhancement and dryout prevention benefits accompanying electrostatic suppression of the Leidenfrost state. Interfacial electric fields in the vapor layer can attract liquid toward the surface and promote wetting. This principle can suppress dryout even at ultrahigh temperatures exceeding 500 °C, which is more than 8 times the Leidenfrost superheat for organic solvents. Robust Leidenfrost state suppression is observed for a variety of liquids, ranging from low electrical conductivity organic solvents to electrically conducting salt solutions. Elimination of the vapor layer increases heat dissipation capacity by more than 1 order of magnitude. Heat removal capacities exceeding 500 W/cm(2) are measured, which is 5 times the critical heat flux (CHF) of water on common engineering surfaces. Furthermore, the heat transfer rate can be electrically controlled by the applied voltage. The underlying science is explained via a multiphysics analytical model which captures the coupled electrostatic-fluid-thermal transport phenomena underlying electrostatic Leidenfrost state suppression. Overall, this work uncovers the physics underlying dryout prevention and demonstrates electrically tunable boiling heat transfer with ultralow power consumption.

  11. Solid-State and Solution Characterization of Myricetin.

    PubMed

    Franklin, Stephen J; Myrdal, Paul B

    2015-12-01

    Myricetin (MYR) is a natural compound that has been investigated as a chemopreventative agent. MYR has been shown to suppresses ultraviolet B (UVB)-induced cyclooxygenase-2 (COX-2) protein expression and reduce the incidence of UVB-induced skin tumors in mice. Despite MYR's promise as a therapeutic agent, minimal information is available to guide the progression of formulations designed for future drug development. Here, data is presented describing the solid-state and solution characterization of MYR. Investigation into the solid-state properties of MYR identified four different crystal forms, two hydrates (MYR I and MYR II) and two metastable forms (MYR IA and MYR IIA). From solubility studies, it was evident that all forms are very insoluble (<5 μg/ml) in pure water. MYR I was found to be the most stable form at 23, 35, and 56°C. Stability determination indicated that MYR undergoes rapid apparent first-order degradation under basic pH conditions, and that degradation was influenced by buffer species. Apparent first-order degradation was also seen when MYR was introduced to an oxidizing solution. Improved stability was achieved after introducing 0.1% antioxidants to the solution. MYR was found to have good stability following exposure to ultraviolet radiation (UVR), which is a consideration for topical applications. Finally, a partitioning study indicated that MYR possess a log P of 2.94 which, along with its solid-state properties, contributes to its poor aqueous solubility. Both the solid-state properties and solution stability of MYR are important to consider when developing future formulations.

  12. Effect of solution saturation state and temperature on diopside dissolution

    SciTech Connect

    Dixit, S; Carroll, S A

    2007-03-23

    Steady-state dissolution rates of diopside are measured as a function of solution saturation state using a titanium flow-through reactor at pH 7.5 and temperature ranging from 125 to 175 C. Diopside dissolved stoichiometrically under all experimental conditions and rates were not dependent on sample history. At each temperature, rates continuously decreased by two orders of magnitude as equilibrium was approached and did not exhibit a dissolution plateau of constant rates at high degrees of undersaturation. The variation of diopside dissolution rates with solution saturation can be described equally well with a ion exchange model based on transition state theory or pit nucleation model based on crystal growth/dissolution theory from 125 to 175 C. At 175 C, both models over predict dissolution rates by two orders of magnitude indicating that a secondary phase precipitated in the experiments. The ion exchange model assumes the formation of a Si-rich, Mg-deficient precursor complex. Lack of dependence of rates on steady-state aqueous calcium concentration supports the formation of such a complex, which is formed by exchange of protons for magnesium ions at the surface.

  13. Anharmonic densities of states: A general dynamics-based solution.

    PubMed

    Jellinek, Julius; Aleinikava, Darya

    2016-06-01

    Density of states is a fundamental physical characteristic that lies at the foundation of statistical mechanics and theoretical constructs that derive from them (e.g., kinetic rate theories, phase diagrams, and others). Even though most real physical systems are anharmonic, the vibrational density of states is customarily treated within the harmonic approximation, or with some partial, often limited, account for anharmonicity. The reason for this is that the problem of anharmonic densities of states stubbornly resisted a general and exact, yet convenient and straightforward in applications, solution. Here we formulate such a solution within both classical and quantum mechanics. It is based on actual dynamical behavior of systems as a function of energy and as observed, or monitored, on a chosen time scale, short or long. As a consequence, the resulting anharmonic densities of states are fully dynamically informed and, in general, time-dependent. As such, they lay the ground for formulation of new statistical mechanical frameworks that incorporate time and are ergodic, by construction, with respect to actual dynamical behavior of systems. PMID:27276941

  14. Investigation on intermolecular interaction between two solutes where one solute occurs in two states

    NASA Astrophysics Data System (ADS)

    Kang, Xiaoyan; He, Anqi; Guo, Ran; Chen, Jing; Zhai, Yanjun; Xu, Yizhuang; Noda, Isao; Wu, Jinguang

    2016-11-01

    The spectral behavior of a pair of 2D asynchronous spectra generated by using the double asynchronous orthogonal sample design (DAOSD) approach on a chemical system is investigated. Two solutes (P and Q) are dissolved in the solution and intermolecular interaction between P and Q is characterized. In this particular system, P occurs in two exchangeable states when it is dissolved in the solutions. Results on mathematical analysis and computer simulation demonstrated that interference unrelated to the intermolecular interaction can be completely removed. Hence the resultant 2D asynchronous spectra generated by using the DAOSD approach can reflect intermolecular interaction reliably. Moreover, properties of cross peaks in different regions of the pair of asynchronous spectra are discussed. In our previous works, cross peaks generated by using the DAOSD and relevant techniques reflect variations on peak position, bandwidth or absorptivity of the characteristic peaks of solutes caused by intermolecular interaction. However, we find that cross peak can still be produced even if intermolecular interaction do not bring about any changes on the characteristic peaks of solutes. Mathematical analysis demonstrates that cross peaks are related to the variations of chemical systems caused by intermolecular interaction at a network level.

  15. Grating enhanced solid-state laser amplifiers

    SciTech Connect

    Erlandson, Alvin C.; Britten, Jerald A.

    2010-11-09

    A novel method and apparatus for suppressing ASE and parasitic oscillation modes in a high average power laser is introduced. Such an invention, as disclosed herein, uses diffraction gratings to increase gain, stored energy density, and pumping efficiency of solid-state laser gain media, such as, but not limited to rods, disks and slabs. By coupling predetermined gratings to solid-state gain media, such as crystal or ceramic laser gain media, ASE and parasitic oscillation modes can be effectively suppressed.

  16. Do State Lotteries Enhance the Financing of Public Education?

    ERIC Educational Resources Information Center

    Jones, Thomas H.; Amalfitano, John L.

    By the late 1980s, fiscal crises, tax revolt measures, education reform, and other factors had prompted 28 states to institute state lotteries as a supplemental means of public finance. This paper presents findings of a study that examined whether or not lotteries enhance public education spending. Data for 1987 from all 50 states were compared…

  17. New solution method for steady-state canopy structural loads

    SciTech Connect

    Sundberg, W.D.

    1986-08-01

    A new computer code has been written to perform structural analysis canopies. Although an existing code, CANO, has been available, the new code has better convergence reliability, is more understandably written, and is easier to use. The equations have been reformulated for the new solution method. The new code assumes a symmetric canopy, a steady-state condition, and no strength in the vertical direction. It computes the inflated shape, loads in the horizontal members, radial members, vent lines, and suspension lines, and total drag. Constructed geometry, material properties, dynamic pressure, and pressure distribution are required as input.

  18. Ground state solutions for non-autonomous fractional Choquard equations

    NASA Astrophysics Data System (ADS)

    Chen, Yan-Hong; Liu, Chungen

    2016-06-01

    We consider the following nonlinear fractional Choquard equation, {(‑Δ)su+u=(1+a(x))(Iα ∗ (|u| p))|u| p‑2uin RN,u(x)→0as |x|→∞, here s\\in (0,1) , α \\in (0,N) , p\\in ≤ft[2,∞ \\right) and \\frac{N-2s}{N+α}<\\frac{1}{p}<\\frac{N}{N+α} . Assume {{\\lim}|x|\\to ∞}a(x)=0 and satisfying suitable assumptions but not requiring any symmetry property on a(x), we prove the existence of ground state solutions for (0.1).

  19. Ground state solutions for non-autonomous fractional Choquard equations

    NASA Astrophysics Data System (ADS)

    Chen, Yan-Hong; Liu, Chungen

    2016-06-01

    We consider the following nonlinear fractional Choquard equation, {(-Δ)su+u=(1+a(x))(Iα ∗ (|u| p))|u| p-2uin RN,u(x)→0as |x|→∞, here s\\in (0,1) , α \\in (0,N) , p\\in ≤ft[2,∞ \\right) and \\frac{N-2s}{N+α}<\\frac{1}{p}<\\frac{N}{N+α} . Assume {{\\lim}|x|\\to ∞}a(x)=0 and satisfying suitable assumptions but not requiring any symmetry property on a(x), we prove the existence of ground state solutions for (0.1).

  20. Enhancing physiologic simulations using supervised learning on coarse mesh solutions.

    PubMed

    Kolandaivelu, Kumaran; O'Brien, Caroline C; Shazly, Tarek; Edelman, Elazer R; Kolachalama, Vijaya B

    2015-03-01

    Computational modelling of physical and biochemical processes has emerged as a means of evaluating medical devices, offering new insights that explain current performance, inform future designs and even enable personalized use. Yet resource limitations force one to compromise with reduced order computational models and idealized assumptions that yield either qualitative descriptions or approximate, quantitative solutions to problems of interest. Considering endovascular drug delivery as an exemplary scenario, we used a supervised machine learning framework to process data generated from low fidelity coarse meshes and predict high fidelity solutions on refined mesh configurations. We considered two models simulating drug delivery to the arterial wall: (i) two-dimensional drug-coated balloons and (ii) three-dimensional drug-eluting stents. Simulations were performed on computational mesh configurations of increasing density. Supervised learners based on Gaussian process modelling were constructed from combinations of coarse mesh setting solutions of drug concentrations and nearest neighbourhood distance information as inputs, and higher fidelity mesh solutions as outputs. These learners were then used as computationally inexpensive surrogates to extend predictions using low fidelity information to higher levels of mesh refinement. The cross-validated, supervised learner-based predictions improved fidelity as compared with computational simulations performed at coarse level meshes--a result consistent across all outputs and computational models considered. Supervised learning on coarse mesh solutions can augment traditional physics-based modelling of complex physiologic phenomena. By obtaining efficient solutions at a fraction of the computational cost, this framework has the potential to transform how modelling approaches can be applied in the evaluation of medical technologies and their real-time administration in an increasingly personalized fashion. PMID:25652458

  1. Enhancing physiologic simulations using supervised learning on coarse mesh solutions

    PubMed Central

    Kolandaivelu, Kumaran; O'Brien, Caroline C.; Shazly, Tarek; Edelman, Elazer R.; Kolachalama, Vijaya B.

    2015-01-01

    Computational modelling of physical and biochemical processes has emerged as a means of evaluating medical devices, offering new insights that explain current performance, inform future designs and even enable personalized use. Yet resource limitations force one to compromise with reduced order computational models and idealized assumptions that yield either qualitative descriptions or approximate, quantitative solutions to problems of interest. Considering endovascular drug delivery as an exemplary scenario, we used a supervised machine learning framework to process data generated from low fidelity coarse meshes and predict high fidelity solutions on refined mesh configurations. We considered two models simulating drug delivery to the arterial wall: (i) two-dimensional drug-coated balloons and (ii) three-dimensional drug-eluting stents. Simulations were performed on computational mesh configurations of increasing density. Supervised learners based on Gaussian process modelling were constructed from combinations of coarse mesh setting solutions of drug concentrations and nearest neighbourhood distance information as inputs, and higher fidelity mesh solutions as outputs. These learners were then used as computationally inexpensive surrogates to extend predictions using low fidelity information to higher levels of mesh refinement. The cross-validated, supervised learner-based predictions improved fidelity as compared with computational simulations performed at coarse level meshes—a result consistent across all outputs and computational models considered. Supervised learning on coarse mesh solutions can augment traditional physics-based modelling of complex physiologic phenomena. By obtaining efficient solutions at a fraction of the computational cost, this framework has the potential to transform how modelling approaches can be applied in the evaluation of medical technologies and their real-time administration in an increasingly personalized fashion. PMID:25652458

  2. Enhanced electrodes for solid state gas sensors

    DOEpatents

    Garzon, Fernando H.; Brosha, Eric L.

    2001-01-01

    A solid state gas sensor generates an electrical potential between an equilibrium electrode and a second electrode indicative of a gas to be sensed. A solid electrolyte substrate has the second electrode mounted on a first portion of the electrolyte substrate and a composite equilibrium electrode including conterminous transition metal oxide and Pt components mounted on a second portion of the electrolyte substrate. The composite equilibrium electrode and the second electrode are electrically connected to generate an electrical potential indicative of the gas that is being sensed. In a particular embodiment of the present invention, the second electrode is a reference electrode that is exposed to a reference oxygen gas mixture so that the electrical potential is indicative of the oxygen in a gas stream.

  3. Enhanced consumption of salient solutions following pedunculopontine tegmental lesions

    PubMed Central

    MacLaren, Duncan AA; Markovic, Tamara; Daniels, Derek; Clark, Stewart D

    2014-01-01

    Rats with lesions of the pedunculopontine tegmental nucleus (PPTg) reliably overconsume high concentration sucrose solution. This effect is thought to be indicative of response-perseveration or loss of behavioral control in conditions of high excitement. While these theories have anatomical and behavioral support, they have never been explicitly tested. Here, we used a contact lickometer to examine the microstructure of drinking behavior to gain insight into the behavioral changes during overconsumption. Rats received either excitotoxic (ibotenic acid) damage to all PPTg neuronal subpopulations or selective depletion of the cholinergic neuronal sub-population (Dtx-UII lesions). We offered rats a variety of pleasant, neutral and aversive tastants to assess the generalizability and specificity of the overconsumption effect. Ibotenic lesioned rats consumed significantly more 20% sucrose than sham controls, and did so through licking significantly more times. However, the behavioral microstructure during overconsumption was unaffected by the lesion and showed no indications of response-perseveration. Furthermore, the overconsumption effect did not generalize to highly consumed saccharin. In contrast, while only consuming small amounts of quinine solution, ibotenic lesioned rats had significantly more licks and bursts for this tastant. Selective depletion of cholinergic PPTg neurons had no effect on consumption of any tastant. We then assessed whether it is the salience of the solution which determines overconsumption by ibotenic lesioned rats. While maintained on free-food, ibotenic lesioned rats had normal consumption of sucrose and hypertonic saline. After mild food deprivation ibotenic PPTg lesioned rats overconsumed 20% sucrose. Subsequently, after dietary induced sodium deficiency, lesioned rats consumed significantly more saline than controls. These results establish that it is the salience of the solution which is the determining factor leading to

  4. Enhanced consumption of salient solutions following pedunculopontine tegmental lesions.

    PubMed

    MacLaren, D A A; Markovic, T; Daniels, D; Clark, S D

    2015-01-22

    Rats with lesions of the pedunculopontine tegmental nucleus (PPTg) reliably overconsume high concentration sucrose solution. This effect is thought to be indicative of response-perseveration or loss of behavioral control in conditions of high excitement. While these theories have anatomical and behavioral support, they have never been explicitly tested. Here, we used a contact lickometer to examine the microstructure of drinking behavior to gain insight into the behavioral changes during overconsumption. Rats received either excitotoxic (ibotenic acid) damage to all PPTg neuronal subpopulations or selective depletion of the cholinergic neuronal sub-population (diphtheria toxin-urotensin II (Dtx-UII) lesions). We offered rats a variety of pleasant, neutral and aversive tastants to assess the generalizability and specificity of the overconsumption effect. Ibotenic-lesioned rats consumed significantly more 20% sucrose than sham controls, and did so through licking significantly more times. However, the behavioral microstructure during overconsumption was unaffected by the lesion and showed no indications of response-perseveration. Furthermore, the overconsumption effect did not generalize to highly consumed saccharin. In contrast, while only consuming small amounts of quinine solution, ibotenic-lesioned rats had significantly more licks and bursts for this tastant. Selective depletion of cholinergic PPTg neurons had no effect on consumption of any tastant. We then assessed whether it is the salience of the solution which determines overconsumption by ibotenic-lesioned rats. While maintained on free-food, ibotenic-lesioned rats had normal consumption of sucrose and hypertonic saline. After mild food deprivation ibotenic PPTg-lesioned rats overconsumed 20% sucrose. Subsequently, after dietary-induced sodium deficiency, lesioned rats consumed significantly more saline than controls. These results establish that it is the salience of the solution which is the determining

  5. Ordering phenomena of star polymer solutions approaching the Θ state

    NASA Astrophysics Data System (ADS)

    Likos, C. N.; Löwen, H.; Poppe, A.; Willner, L.; Roovers, J.; Cubitt, B.; Richter, D.

    1998-11-01

    The liquid-state ordering phenomena of a semidilute polybutadiene 64-arm star polymer solution were investigated by small-angle neutron scattering. For this purpose, we used deuterated 1,4-dioxane, which is a Θ solvent for the star at 31.5 °C. Its quality was modified by varying the temperature in the range between 40 °C and 80 °C. Besides a swelling of the star, with increasing temperature the development of a strong correlation peak was observed in the experiment. The experimental data were described theoretically by employing an effective pair potential between stars which was introduced earlier by Mewis et al. [J. Mewis, W. J. Frith, T. A. Strivens, and W. B. Russel, AIChE J. 35, 415 (1989)].

  6. Steady state solutions to dynamically loaded periodic structures

    NASA Technical Reports Server (NTRS)

    Kalinowski, A. J.

    1980-01-01

    The general problem of solving for the steady state (time domain) dynamic response (i.e., NASTRAN rigid format-8) of a general elastic periodic structure subject to a phase difference loading of the type encountered in traveling wave propagation problems was studied. Two types of structural configurations were considered; in the first type, the structure has a repeating pattern over a span that is long enough to be considered, for all practical purposes, as infinite; in the second type, the structure has structural rotational symmetry in the circumferential direction. The theory and a corresponding set of DMAP instructions which permits the NASTRAN user to automatically alter the rigid format-8 sequence to solve the intended class of problems are presented. Final results are recovered as with any ordinary rigid format-8 solution, except that the results are only printed for the typical periodic segment of the structure. A simple demonstration problem having a known exact solution is used to illustrate the implementation of the procedure.

  7. Sensitivity Enhancement in Solution NMR: Emerging Ideas and New Frontiers

    PubMed Central

    Lee, Jung Ho; Okuno, Yusuke; Cavagnero, Silvia

    2014-01-01

    Modern NMR spectroscopy has reached an unprecedented level of sophistication in the determination of biomolecular structure and dynamics at atomic resolution in liquids. However, the sensitivity of this technique is still too low to solve a variety of cutting-edge biological problems in solution, especially those that involve viscous samples, very large biomolecules or aggregation-prone systems that need to be kept at low concentration. Despite the challenges, a variety of efforts have been carried out over the years to increase sensitivity of NMR spectroscopy in liquids. This review discusses basic concepts, recent developments and future opportunities in this exciting area of research. PMID:24656077

  8. NEXAFS Chemical State and Bond Lengths of p-Aminobenzoic Acid in Solution and Solid State

    NASA Astrophysics Data System (ADS)

    Stevens, J. S.; Gainar, A.; Suljoti, E.; Xiao, J.; Golnak, R.; Aziz, E. F.; Schroeder, S. L. M.

    2016-05-01

    Solid-state and solution pH-dependent NEXAFS studies allow direct observation of the electronic state of para-aminobenzoic acid (PABA) as a function of its chemical environment, revealing the chemical state and bonding of the chemical species. Variations in the ionization potential (IP) and 1s→π* resonances unequivocally identify the chemical species (neutral, cationic, or anionic) present and the varying local environment. Shifts in σ* shape resonances relative to the IP in the NEXAFS spectra vary with C-N bond length, and the important effect of minor alterations in bond length is confirmed with nitrogen FEFF calculations, leading to the possibility of bond length determination in solution.

  9. Realities and Choices: Helping States Enhance Family Economic Security.

    ERIC Educational Resources Information Center

    Venner, Sandra

    This document, which is designed to help state administrators and legislators formulate policies enhancing family economic security, summarizes research findings regarding barriers to economic self-sufficiency and policies used by various states to improve poor family's available work opportunities and economic security. Discussed in the…

  10. Enhanced non-Gaussianity from excited initial states

    SciTech Connect

    Holman, R; Tolley, Andrew J E-mail: atolley@perimeterinstitute.ca

    2008-05-15

    We use the techniques of effective field theory in an expanding universe to examine the effect of choosing an excited inflationary initial state built over the Bunch-Davies state on the CMB bi-spectrum. We find that, even for Hadamard states, there are unexpected enhancements in the bi-spectrum for certain configurations in momentum space due to interactions of modes in the early stages of inflation. These enhancements can be parametrically larger than the standard ones and are potentially observable in future data. These initial state effects have a characteristic signature in l-space which distinguishes them from the usual contributions, with the enhancement being most pronounced for configurations corresponding to flattened triangles for which two momenta are collinear.

  11. States leverage telepsychiatry solutions to ease ED crowding, accelerate care.

    PubMed

    2015-02-01

    Many states are having success turning to telepsychiatry-based solutions to connect mental health patients with needed care while also decompressing crowded EDs. Just one year into a statewide telepsychiatry initiative in North Carolina (NC-STeP), administrators say the approach has saved as much as $7 million, and hospital demand for the service is higher than anticipated. In Texas, mental health emergency centers (MHEC) that use telepsychiatry to connect patients in rural areas with needed psychiatric care are freeing up EDs to focus on medical care. In just 11 months, 91 North Carolina hospitals have at least started the process to engage in NC-STeP. Much of the savings from NC-STeP come from involuntary commitment orders being overturned as a result of the telepsychiatry consults, reducing the need for expensive inpatient care. Implementing NC-STeP has involved multiple hurdles including credentialing difficulties and technical/firewall challenges. The Texas model provides 24/7 availability of psychiatrists via telemedicine through a network of MHECs. In-person staff at the MHECs perform basic screening tests and blood draws so that medical clearance can be achieved without the need for an ED visit in most cases. Funding for the MHECs comes from the state, hospitals in the region, and local governmental authorities that reap savings or benefits from the initiative. PMID:25688413

  12. States leverage telepsychiatry solutions to ease ED crowding, accelerate care.

    PubMed

    2015-02-01

    Many states are having success turning to telepsychiatry-based solutions to connect mental health patients with needed care while also decompressing crowded EDs. Just one year into a statewide telepsychiatry initiative in North Carolina (NC-STeP), administrators say the approach has saved as much as $7 million, and hospital demand for the service is higher than anticipated. In Texas, mental health emergency centers (MHEC) that use telepsychiatry to connect patients in rural areas with needed psychiatric care are freeing up EDs to focus on medical care. In just 11 months, 91 North Carolina hospitals have at least started the process to engage in NC-STeP. Much of the savings from NC-STeP come from involuntary commitment orders being overturned as a result of the telepsychiatry consults, reducing the need for expensive inpatient care. Implementing NC-STeP has involved multiple hurdles including credentialing difficulties and technical/firewall challenges. The Texas model provides 24/7 availability of psychiatrists via telemedicine through a network of MHECs. In-person staff at the MHECs perform basic screening tests and blood draws so that medical clearance can be achieved without the need for an ED visit in most cases. Funding for the MHECs comes from the state, hospitals in the region, and local governmental authorities that reap savings or benefits from the initiative.

  13. Enhanced Communication Network Solution for Positive Train Control Implementation

    NASA Technical Reports Server (NTRS)

    Fatehi, M. T.; Simon, J.; Chang, W.; Chow, E. T.; Burleigh, S. C.

    2011-01-01

    The commuter and freight railroad industry is required to implement Positive Train Control (PTC) by 2015 (2012 for Metrolink), a challenging network communications problem. This paper will discuss present technologies developed by the National Aeronautics and Space Administration (NASA) to overcome comparable communication challenges encountered in deep space mission operations. PTC will be based on a new cellular wireless packet Internet Protocol (IP) network. However, ensuring reliability in such a network is difficult due to the "dead zones" and transient disruptions we commonly experience when we lose calls in commercial cellular networks. These disruptions make it difficult to meet PTC s stringent reliability (99.999%) and safety requirements, deployment deadlines, and budget. This paper proposes innovative solutions based on space-proven technologies that would help meet these challenges: (1) Delay Tolerant Networking (DTN) technology, designed for use in resource-constrained, embedded systems and currently in use on the International Space Station, enables reliable communication over networks in which timely data acknowledgments might not be possible due to transient link outages. (2) Policy-Based Management (PBM) provides dynamic management capabilities, allowing vital data to be exchanged selectively (with priority) by utilizing alternative communication resources. The resulting network may help railroads implement PTC faster, cheaper, and more reliably.

  14. Solution-state polymer assemblies influence BCS class II drug dissolution and supersaturation maintenance.

    PubMed

    Dalsin, Molly C; Tale, Swapnil; Reineke, Theresa M

    2014-02-10

    Spray dried dispersions (SDDs), solid dispersions of polymer excipients and active pharmaceuticals, are important to the field of oral drug delivery for improving active stability, bioavailability, and efficacy. Herein, we examine the influence of solution-state polymer assemblies on amorphous spray-dried dispersion (SDD) performance with two BCS II model drugs, phenytoin and probucol. These drugs were spray dried with 4 model polymer excipients consisting of poly(ethylene-alt-propylene) (PEP), N,N,-dimethylacrylamide (DMA), or 2-methacrylamido glucopyranose (MAG): amphiphilic diblock ter- and copolymers, PEP-P(DMA-grad-MAG) and PEP-PDMA, and their respective hydrophilic analogues, P(DMA-grad-MAG) and PDMA. Selective and nonselective solvents for the hydrophilic block of the diblock ter- and copolymers were used to induce or repress solution-state assemblies prior to spray drying. Prespray dried solution-state assemblies of these four polymers were probed with dynamic light scattering (DLS) and showed differences in solution assembly size and structure (free polymer versus aggregates versus micelles). Solid-state structures of spray dried dispersions (SDDs) showed a single glass transition event implying a homogeneous mixture of drug/polymer. Crystallization temperatures and enthalpies indicated that the drugs interact mostly with the DMA-containing portions of the polymers. Scanning electron microscopy was used to determine SDD particle size and morphology for the various polymer-drug pairings. In vitro dissolution tests showed excellent performance for one system, spray-dried PEP-PDMA micelles with probucol. Dissolution structures were investigated through DLS to determine drug-polymer aggregates that lead to enhanced SDD performance. Forced aggregation of the polymer into regular micelle structures was found to be a critical factor to increase the dissolution rate and supersaturation maintenance of SDDs, and may be an attractive platform to exploit in excipient

  15. Enhancing performance characteristics of organic semiconducting films by improved solution processing

    SciTech Connect

    Bazan, Guillermo C; Heeger, Alan J; Moses, Daniel; Peet, Jeffrey

    2013-09-25

    Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

  16. Enhancing performing characteristics of organic semiconducting films by improved solution processing

    SciTech Connect

    Bazan, Guillermo C; Moses, Daniel; Peet, Jeffrey; Heeger, Alan J

    2014-05-13

    Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

  17. Enhancing performance characteristics of organic semiconducting films by improved solution processing

    SciTech Connect

    Bazan, Guillermo C; Mikhailovsky, Alexander; Moses, Daniel; Nguyen, Thuc-Quyen; Peet, Jeffrey; Soci, Cesare

    2012-11-27

    Improved processing methods for enhanced properties of conjugated polymer films are disclosed, as well as the enhanced conjugated polymer films produced thereby. Addition of low molecular weight alkyl-containing molecules to solutions used to form conjugated polymer films leads to improved photoconductivity and improvements in other electronic properties. The enhanced conjugated polymer films can be used in a variety of electronic devices, such as solar cells and photodiodes.

  18. Carbohydrate Electrolyte Solutions Enhance Endurance Capacity in Active Females

    PubMed Central

    Sun, Feng-Hua; Wong, Stephen Heung-Sang; Chen, Shi-Hui; Poon, Tsz-Chun

    2015-01-01

    The purpose of the present study was to investigate the effects of supplementation with a carbohydrate-electrolyte solution (CES) in active females during a prolonged session of submaximal running to exhaustion. Eight healthy active females volunteered to perform a session of open-ended running to exhaustion at 70% of their maximal oxygen consumption on a treadmill during the follicular phase of their menstrual cycle on two occasions. During each run, the subjects consumed either 3mL·kg−1 body mass of a 6% CES or a placebo drink (PL) every 20 min during exercise. The trials were administered in a randomized double-blind, cross-over design. During the run, the subjects ingested similar volumes of fluid in two trials (CES: 644 ± 75 mL vs. PL: 593 ± 66 mL, p > 0.05). The time to exhaustion was 16% longer during the CES trial (106.2 ± 9.4 min) than during the PL trial (91.6 ± 5.9 min) (p < 0.05). At 45 min during exercise, the plasma glucose concentration in the CES trial was higher than that in PL trial. No differences were observed in the plasma lactate level, respiratory exchange ratio, heart rate, perceived rate of exertion, sensation of thirst, or abdominal discomfort between the two trials (p > 0.05). The results of the present study confirm that CES supplementation improves the moderate intensity endurance capacity of active females during the follicular phases of the menstrual cycle. However, the exogenous oxidation of carbohydrate does not seem to explain the improved capacity after CES supplementation. PMID:25988766

  19. The nature of enhanced linear and nonlinear optical effects in fullerene solutions

    SciTech Connect

    Sheka, E. F. Razbirin, B. S. Starukhin, A. N.; Nelson, D. K.; Degunov, M. Yu.; Lyubovskaya, R. N.; Troshin, P. A.

    2009-05-15

    The 'blue' emission from fullerene C{sub 60} and its derivatives in frozen toluene solution is discovered and analyzed in the framework of the electromagnetic theory of enhanced optical effects. It is shown that the emission, combining enhanced spectra of Raman scattering and one-photon luminescence, is due to clustering of fullerene molecules in solution. Photoexcitation of charge-transfer excitons in clusters provides the polarization required for the enhancement. A direct relationship is established between the observed phenomenon and nonlinear optical properties of the medium. Empirical and computational tests are proposed to select matrices with various nonlinear optical properties.

  20. Enhancement of stability in systems with metastable states

    SciTech Connect

    Spagnolo, B.; Augello, G.; Pizzolato, N.; Valenti, D.; Fiasconaro, A.

    2007-12-06

    The investigation of noise-induced phenomena in far from equilibrium systems is one of the approach used to understand the behaviour of physical and biological complex systems. Metastability is a generic feature of many nonlinear systems, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. The enhancement of the life-time of metastable states through the noise enhanced stability effect and the role played by the resonant activation phenomenon will be discussed in models of interdisciplinary physics: (i) Ising model (ii) Josephson junction; (iii) stochastic FitzHugh-Nagumo model; (iv) a population dynamics model, and (v) a market model with stochastic volatility.

  1. Solid state lighting for the developing world: the only solution

    NASA Astrophysics Data System (ADS)

    Peon, Rudolfo; Doluweera, Ganesh; Platonova, Inna; Irvine-Halliday, Dave; Irvine-Halliday, Gregor

    2005-09-01

    Approximately two billion people, one third of humanity still has no access to electricity, and thus relies on fuel-based lighting, a dangerous alternative of last resort that is unhealthy, expensive, and offers very poor levels of illumination. This lack of light makes it difficult to perform most evening activities including studies by children and adults alike and therefore represents a significant barrier to human development. Over the past five years The Light Up The World Foundation (LUTW) has pioneered the use of the white light emitting diode (WLED) as an alternative home lighting solution, bringing clean, affordable light to thousands of non-electrified homes around the world. The information presented herein is intended to increase awareness of the enormous potential possessed by this emergent technology, "Solid State Lighting" (SSL), to improve the quality of life of millions of people around the world. The feasibility of its implementation is demonstrated with results from comprehensive field experience and laboratory research work. The mutual economic, social and environmental benefits for both stakeholders and SSL suppliers are discussed. Strategies conducive to the dissemination of this technology throughout the developing world are also presented.

  2. Unsteady-state transfer of impurities during crystal growth of sucrose in sugarcane solutions

    NASA Astrophysics Data System (ADS)

    Martins, P. M.; Ferreira, A.; Polanco, S.; Rocha, F.; Damas, A. M.; Rein, P.

    2009-07-01

    In this work, we present growth rate data of sucrose crystals in the presence of impurities that can be used by both sugar technologists and crystal growth scientists. Growth rate curves measured in a pilot-scale evaporative crystallizer suggest a period of slow growth that follows the seeding of crystals into supersaturated technical solutions. The observed trend was enhanced by adding typical sugarcane impurities such as starch, fructose or dextran to the industrial syrups. Maximum growth rates of sucrose resulted at intermediate rather than high supersaturation levels in the presence of the additives. The effects of the additives on the sucrose solubility and sucrose mass transfer in solution were taken into account to explain the observed crystal growth kinetics. A novel mechanism was identified of unsteady-state adsorption of impurities at the crystal surface and their gradual replacement by the crystallizing solute towards the equilibrium occupation of the active sites for growth. Specifically designed crystallization experiments at controlled supersaturation confirmed this mechanism by showing increasing crystal growth rates with time until reaching a steady-state value for a given supersaturation level and impurity content.

  3. Novel silver nanoparticle-enhanced fluorometric determination of trace tetracyclines in aqueous solutions.

    PubMed

    Wang, Ping; Wu, Tun-Hua; Zhang, Yong

    2016-01-01

    Metal-enhanced fluorescence (MEF) has exhibited promise for applications in fluorometric assays. The effects of silver nanoparticles (AgNP) on the fluorescence behaviours of tetracycline hydrochloride (TCH) and chlortetracycline hydrochloride (CTC) in aqueous solutions were investigated. The experimental results demonstrated that the fluorescence intensities of each tetracycline in water solutions were greatly enhanced by AgNP through the MEF effect. In addition, a novel silver nanoparticle-enhanced fluorometric method was established for the direct determination of TCH and CTC in aqueous solutions. Under optimum experimental conditions, the linear dynamic ranges for the determination of TCH and CTC in aqueous solutions varied from 0.10 to 6.0 mg L(-1) and 0.050 to 3.0 mg L(-1) with detection limits of 0.63 µg L(-1) and 0.19 µg L(-1), respectively, and with the relative standard deviation of less than 1.9% (n=9). The experimental recovery results for the determination of TCH and CTC in aqueous solutions ranged from 93-106% and 95-104%, respectively. Compared with the established method without the addition of AgNP, the limits of quantitation of the silver nanoparticle-enhanced fluorometric method were approximately 5-fold lower for TCH and 3-fold lower for CTC. Moreover, the newly established silver nanoparticle-enhanced fluorometric method was successfully applied to the direct determination of TCH and CTC in pharmaceutical preparations.

  4. Selecting enhancing solutions for electrokinetic remediation of dredged sediments polluted with fuel.

    PubMed

    Rozas, F; Castellote, M

    2015-03-15

    In this paper a procedure for selecting the enhancing solutions in electrokinetic remediation experiments is proposed. For this purpose, dredged marine sediment was contaminated with fuel, and a total of 22 different experimental conditions were tested, analysing the influence of different enhancing solutions by using three commercial non-ionic surfactants, one bio-surfactant, one chelating agent, and one weak acid. Characterisation, microelectrophoretic and electrokinetic remediation trials were carried out. The results are explained on the basis of the interactions between the fuel, the enhancing electrolytes and the matrix. For one specific system, the electrophoretic zeta potential, (ζ), of the contaminated matrix in the solution was found to be related to the electroosmotic averaged ζ in the experiment and not to the efficiency in the extraction. This later was correlated to a parameter accounting for both contributions, the contaminant and the enhancing solution, calculated on the basis of differences in the electrophoretic ζ in different conditions which has allowed to propose a methodology for selection of enhancing solutions. PMID:25559497

  5. Permeability in a state of partial solidification of aqueous solution

    NASA Astrophysics Data System (ADS)

    Okada, Masashi; Kang, Chaedong; Okiyama, Haruhiko

    A mushy region was formed by solidifying NaCl aqueous solution in a circular tube or a rectangular tube. The measurements of permeability were performed by changing volume fraction of liquid region in the mushy region. The dendritic ice in the solidification process was observed with a CCD microscope. The following results were obtained. The permeability increases with the volume fraction of liquid phase, and decreases with increasing the super-cooling degree of the solution or increasing the initial concentration of the solution, and is constant after the mushy region was formed. The arm space of dendrite becomes narrower as the super-cooling degree of the solution increases.

  6. Complete solution for unambiguous discrimination of three pure states with real inner products

    SciTech Connect

    Sugimoto, H.; Hashimoto, T.; Horibe, M.; Hayashi, A.

    2010-09-15

    Complete solutions are given in a closed analytic form for unambiguous discrimination of three general pure states with real mutual inner products. For this purpose, we first establish some general results on unambiguous discrimination of n linearly independent pure states. The uniqueness of solution is proved. The condition under which the problem is reduced to an (n-1)-state problem is clarified. After giving the solution for three pure states with real mutual inner products, we examine some difficulties in extending our method to the case of complex inner products. There is a class of set of three pure states with complex inner products for which we obtain an analytical solution.

  7. Solutions of the Noh Problem for Various Equations of State Using Lie Groups

    SciTech Connect

    Axford, R.A.

    1998-08-01

    A method for developing invariant equations of state for which solutions of the Noh problem will exist is developed. The ideal gas equation of state is shown to be a special case of the general method. Explicit solutions of the Noh problem in planar, cylindrical and spherical geometry are determined for a Mie-Gruneisen and the stiff gas equation of state.

  8. Relationships between the solution and solid-state properties of solution-cast low-k silica thin films.

    PubMed

    Chiang, Chao-Ching; Su, Chien-You; Yang, An-Chih; Wang, Ting-Yu; Lee, Wen-Ya; Hua, Chi-Chung; Kang, Dun-Yen

    2016-07-27

    This paper reports on the fabrication of low-k (amorphous) silica thin films cast from solutions without and with two different types of surfactants (TWEEN® 80 and Triton™ X-100) to elucidate the relationships between the structural/morphological features of the casting solutions and the physical properties of the resulting thin films. Cryogenic transmission microscopy (cryo-TEM), static/dynamic light scattering (SLS/DLS), and small-angle X-ray scattering (SAXS) revealed contrasting colloidal dispersion states and phase behavior among the three casting solutions. Casting solution with the Triton™ X-100 surfactant produced stable (>90 days) nanoparticles with good dispersion in solution (mean particle size ∼10 nm) as well as good mesopore volume (characterized by nitrogen physisorption) in powder and thin films of high mechanical strength (characterized by the nanoindentation test). The longer main chain and bulkier side units of the TWEEN® 80 surfactant led to stable micelle-nanoparticle coexisting dispersion, which resulted in the highest mesopore volume in powder and thin films with the lowest dielectric constant (∼3) among the samples in this study. The casting solution without the surfactant failed to produce a stabilized solution or thin films of acceptable uniformity. These findings demonstrate the possibility of fine-tuning low-k silica film properties by controlling the colloidal state of casting solutions. PMID:27401818

  9. Controlling Molecular Ordering in Solution-State Conjugated Polymers

    SciTech Connect

    Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; Hong, Kunlun; Bonnesen, Peter V.; Sumpter, Bobby G.; Smith, Gregory Scott; Ivanov, Ilia N.; Do, Changwoo

    2015-07-17

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.

  10. Controlling molecular ordering in solution-state conjugated polymers

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Han, Y.; Kumar, R.; He, Y.; Hong, K.; Bonnesen, P. V.; Sumpter, B. G.; Smith, S. C.; Smith, G. S.; Ivanov, I. N.; Do, C.

    2015-09-01

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering

  11. Ultraviolet resonance Raman spectroscopy of explosives in solution and the solid state.

    PubMed

    Emmons, Erik D; Tripathi, Ashish; Guicheteau, Jason A; Fountain, Augustus W; Christesen, Steven D

    2013-05-23

    Resonance Raman cross sections of common explosives have been measured by use of excitation wavelengths in the deep-UV from 229 to 262 nm. These measurements were performed both in solution and in the native solid state for comparison. While measurements of UV Raman cross sections in solution with an internal standard are straightforward and commonly found in the literature, measurements on the solid phase are rare. This is due to the difficulty in preparing a solid sample in which the molecules of the internal standard and absorbing analyte/explosive experience the same laser intensity. This requires producing solid samples that are mixtures of strongly absorbing explosives and an internal standard transparent at the UV wavelengths used. For the solid-state measurements, it is necessary to use nanostructured mixtures of the explosive and the internal standard in order to avoid this bias due to the strong UV absorption of the explosive. In this study we used a facile spray-drying technique where the analyte of interest was codeposited with the nonresonant standard onto an aluminum-coated microscope slide. The generated resonance enhancement profiles and quantitative UV-vis absorption spectra were then used to plot the relative Raman return as a function of excitation wavelength and particle size.

  12. 2D steady-state general solution and fundamental solution for fluid-saturated, orthotropic, poroelastic materials

    NASA Astrophysics Data System (ADS)

    Pan, Li-Hua; Hou, Peng-Fei; Chen, Jia-Yun

    2016-08-01

    The 2D steady-state solutions regarding the expressions of stress and strain for fluid-saturated, orthotropic, poroelastic plane are derived in this paper. For this object, the general solutions of the corresponding governing equation are first obtained and expressed in harmonic functions. Based on these compact general solutions, the suitable harmonic functions with undetermined constants for line fluid source in the interior of infinite poroelastic body and a line fluid source on the surface of semi-infinite poroelastic body are presented, respectively. The fundamental solutions can be obtained by substituting these functions into the general solution, and the undetermined constants can be obtained by the continuous conditions, equilibrium conditions and boundary conditions.

  13. Solid state and solution nitrate photochemistry: photochemical evolution of the solid state lattice.

    PubMed

    Asher, Sanford A; Tuschel, David D; Vargson, Todd A; Wang, Luling; Geib, Steven J

    2011-05-01

    We examined the deep UV 229 nm photochemistry of NaNO(3) in solution and in the solid state. In aqueous solution excitation within the deep UV NO(3)¯ strong π → π* transition causes the photochemical reaction NO(3)¯ → NO(2)¯ + O·. We used UV resonance Raman spectroscopy to examine the photon dose dependence of the NO(2)¯ band intensities and measure a photochemical quantum yield of 0.04 at pH 6.5. We also examined the response of solid NaNO(3) samples to 229 nm excitation and also observe formation of NO(2)¯. The quantum yield is much smaller at ∼10(-8). The solid state NaNO(3) photochemistry phenomena appear complex by showing a significant dependence on the UV excitation flux and dose. At low flux/dose conditions NO(2)¯ resonance Raman bands appear, accompanied by perturbed NO(3)¯ bands, indicating stress in the NaNO(3) lattice. Higher flux/dose conditions show less lattice perturbation but SEM shows surface eruptions that alleviate the stress induced by the photochemistry. Higher flux/dose measurements cause cratering and destruction of the NaNO(3) surface as the surface layers are converted to NO(2)¯. Modest laser excitation UV beams excavate surface layers in the solid NaNO(3) samples. At the lowest incident fluxes a pressure buildup competes with effusion to reach a steady state giving rise to perturbed NO(3)¯ bands. Increased fluxes result in pressures that cause the sample to erupt, relieving the pressure.

  14. Future Models of Higher Education in Scotland: Can Collaborative, Technology-Enhanced Learning Offer Solutions?

    ERIC Educational Resources Information Center

    Comrie, Andrew

    2011-01-01

    Purpose: This paper aims to discuss and provide examples of different collaborative models that are emerging and to argue that a technology-enhanced, socio-constructivist approach to future collaborative curriculum design and delivery enables partnership working and provides curriculum design solutions that supports delivery in different ways. The…

  15. Enhancing Pre-Service Elementary Teachers' Conceptual Understanding of Solution Chemistry with Conceptual Change Text

    ERIC Educational Resources Information Center

    Calik, Muammer; Ayas, Alipasa; Coll, Richard Kevin

    2007-01-01

    This paper reports on the use of a constructivist-based pedagogy to enhance understanding of some features of solution chemistry. Pre-service science teacher trainees' prior knowledge about the dissolution of salts and sugar in water were elicited by the use of a simple diagnostic tool. The test revealed widespread alternative conceptions. These…

  16. Argentine ant (Hymenoptera: Formicidae) trail pheromone enhances consumption of liquid sucrose solution.

    PubMed

    Greenberg, L; Klotz, J H

    2000-02-01

    We investigated whether the Argentine ant, Linepithema humile (Mayr), trail pheromone, Z9-16:Ald, could enhance recruitment to and consumption of liquid sucrose solutions. All tests were done as paired comparisons with a 10% sucrose solution as food. In the laboratory, mixing 20 microl of a 10-microg/ml solution of the pheromone with 50 microl of the 10% sucrose solution increased the number of ants feeding by >150%. In a field test, we combined the trail pheromone with a 10% sucrose solution in 50-ml vials. These vials were covered with a plastic membrane that has 1.5-mm-diameter holes punched uniformly across its surface. Ants could drink from the holes after the vials were inverted. For half of the vials, 1 microg of the pheromone was put onto the plastic membrane before the vials were filled with a 10% sucrose solution. The remaining vials had no pheromone on the plastic membrane. After 4 h we measured the consumption in each vial. Bait consumption with the pheromone was enhanced by 29%. In a 2nd series of tests, vials were left outside for 24 h. The consumption rate was 33% higher with the pheromone compared with the controls that didn't have pheromone. PMID:14658521

  17. Controlling molecular ordering in solution-state conjugated polymers.

    PubMed

    Zhu, J; Han, Y; Kumar, R; He, Y; Hong, K; Bonnesen, P V; Sumpter, B G; Smith, S C; Smith, G S; Ivanov, I N; Do, C

    2015-10-01

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.

  18. Controlling Molecular Ordering in Solution-State Conjugated Polymers

    DOE PAGES

    Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; Hong, Kunlun; Bonnesen, Peter V.; Sumpter, Bobby G.; Smith, Gregory Scott; Ivanov, Ilia N.; Do, Changwoo

    2015-07-17

    Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution,more » we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.« less

  19. NASA Water-Cycle Solutions Networks and Community of Practice Approaches to enhance Decision-making

    NASA Astrophysics Data System (ADS)

    Pozzi, W.; Ward, J.; Cox, E. L.; Lawford, R. G.; Matthews, D.; Houser, P.; Doherty, M.

    2009-12-01

    The Japanese Aerospace Exploration Agency (JAXA) has created the Asian Water Cycle Initiative regional network for South Asia and NASA has launched two networks to enhance the rapid transitioning of scientific achievements and NASA technology into operational use. All three networks meet a new type of scientific challenge by providing strong linkage among the scientific communities, the space agencies, and decision makers. We focus here on the two NASA-sponsored networks that carry out complementary approaches: WaterNet focused on large-scale national/international collaborations; North Olympic Peninsula Solution Network developed a local proof of concept project first, then began integration and collaboration at progressively larger scales, culminating with a national-level discourse via the National Association of Resource, Conservation and Development councils (NARC&DC). The ultimate goals of both groups were to bring NASA Science and Technology products to organizations/groups to improve decision making and to create collaborations and networks that would extend beyond the parent groups and expand and continue to be sustainable, after the original projects were completed. This paper provides a summary of lessons learned. The primary objective of the NOPSN is to bring NASA science and technology tools to watershed managers to improve the scientific basis of decision making in NASA national application areas of water management, agricultural efficiency, and ecological forecasting. To achieve this objective, the NOPSN team first developed and implemented a local proof-of-concept project for the Dungeness River, Washington, to improve water forecasting. The team then developed local and regional collaborations with water resource managers, stakeholder groups, and local, state, and federal agencies to identify environmental issues, challenges, and needs that could be addressed with NASA technology. Finally,through its partnership with NARC&D, it provided the NOPSN

  20. Is State-Mandated Redesign an Effective and Sustainable Solution?

    ERIC Educational Resources Information Center

    Young, Michelle D.

    2013-01-01

    There is a pervasive and ongoing perception that leadership preparation is a problem. Important questions remain about the intentions, capacity, and impact of state departments of education engaged in leadership preparation program redesign. In this essay, I take up several issues concerning this state policy work, including whether a one size…

  1. Enhancement of phosphorescence and unimolecular behavior in the solid state by perfect insulation of platinum-acetylide polymers.

    PubMed

    Masai, Hiroshi; Terao, Jun; Makuta, Satoshi; Tachibana, Yasuhiro; Fujihara, Tetsuaki; Tsuji, Yasushi

    2014-10-22

    Controlling the thermal fluctuations and molecular environment of a phosphorescent polymer backbone is vital to enhancing its phosphorescence intensity in the solid state. Here, we demonstrate enhanced phosphorescence control through a systematic investigation of cyclodextrin-based insulated platinum-acetylide polymers with well-defined coverage areas. Modification of the coverage areas revealed two unprecedented effects of macrocyclic insulation on phosphorescence behavior. First, the insulation of particular areas suppresses the thermal relaxation processes of the triplet species because of the restriction of structural fluctuations. Cyclic insulation fixes a polymer chain and concomitantly enhances the phosphorescence intensity in both the solution and solid states. Second, complete three-dimensional insulation protects the polymer from interactions with other platinum and acetylide units, and even oxygen molecules. Notably, these polymers display identical phosphorescence behaviors in both the solution and solid states, essentially achieving "unimolecular phosphorescence."

  2. The use of series-solutions for batch and sequential estimation. [of nonlinear spacecraft state

    NASA Technical Reports Server (NTRS)

    Feagin, T.; Mikkilineni, R. P.

    1975-01-01

    Iterative methods for the approximate solution of the nonlinear state estimation problem are investigated in which the solution is retained in the form of a finite series of Chebyshev polynomials. Algorithms are presented which allow the state to be estimated from observational data in either the batch or the sequential form. The advantages of these techniques are discussed.

  3. Positive bound state solutions for some Schrödinger-Poisson systems

    NASA Astrophysics Data System (ADS)

    Cerami, Giovanna; Molle, Riccardo

    2016-10-01

    The paper deals with a class of Schrödinger-Poisson systems, where the coupling term and the other coefficients do not have any symmetry property. Moreover, the setting we consider does not allow the existence of ground state solutions. Under suitable assumptions on the decay rate of the coefficients, we prove existence of a bound state, finite energy solution.

  4. Enhanced photovoltaic performance of organic/silicon nanowire hybrid solar cells by solution-evacuated method.

    PubMed

    Wang, Wei-Li; Zou, Xian-Shao; Zhang, Bin; Dong, Jun; Niu, Qiao-Li; Yin, Yi-An; Zhang, Yong

    2014-06-01

    A method has been developed to fabricate organic-inorganic hybrid heterojunction solar cells based on n-type silicon nanowire (SiNW) and poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) hybrid structures by evacuating the PEDOT:PSS solution with dip-dropping on the top of SiNWs before spin-coating (solution-evacuating). The coverage and contact interface between PEDOT:PSS and SiNW arrays can be dramatically enhanced by optimizing the solution-evacuated time. The maximum power conversion efficiency (PCE) reaches 9.22% for a solution-evacuated time of 2 min compared with 5.17% for the untreated pristine device. The improvement photovoltaic performance is mainly attributed to better organic coverage and contact with an n-type SiNW surface.

  5. Yields of excited states of solutes in irradiated benzene and cyclohexane

    SciTech Connect

    Choi, H.T.; Hirayama, F.; Lipsky, S.

    1984-09-13

    The yields of lowest excited singlet states of diphenyloxazole and p-terphenyl in benzene and of diphenyloxazole, p-terphenyl, and biphenyl in cyclohexane have been measured for excitation by using /sup 85/Kr ..beta.. particles. The dependence of the yield on solute concentration for benzene solutions is shown to be accurately represented by a Stern-Volmer function from 5 x 10/sup -4/ to 10/sup -2/ M and to extrapolate at infinite solute concentration to the yield of excited singlet states of neat liquid benzene. The presence of oxygen in the solution does not affect the extrapolation. The absolute efficiencies of energy transfer from irradiated benzene to the solutes are in good agreement with previous measurements made by using optical excitation below the ionization threshold. These results provide additional confirmation that the mechanism of formation of excited solute states in fast-electron-irradiated benzene does not significantly involve electron or hole capture by the solute. They also demonstrate that the inhomogeneity of energy deposition does not affect the ratio of probabilities of the decay of excited benzene by photon emission to its decay by nonradiative energy transfer to the solute. For cyclohexane solutions, it is confirmed that the yields of excited solute states are lower than in benzene solutions at comparable concentration, but larger than would be expected were the same nonionic mechanism to apply as it does in benzene. The consequences of these conclusions are discussed.

  6. Enhanced photoluminescence from group 14 metalloles in aggregated and solid solutions.

    PubMed

    Tracy, Henry J; Mullin, Jerome L; Klooster, Wim T; Martin, James A; Haug, Judith; Wallace, Scott; Rudloe, Isaac; Watts, Kimberly

    2005-03-21

    The unusual photoluminescence characteristics of a series of six group 14 metalloles (1,1-dimethyl-2,3,4,5-tetraphenylmetalloles and 1,1-diphenyl-2,3,4,5-tetraphenylmetalloles) containing silicon, germanium, or tin have been investigated. Although the compounds are weakly luminescent in dilute fluid solution at room temperature, they undergo a substantial enhancement of photoluminescence when forced to aggregate, as in mixed solvent systems. The compounds also exhibit considerable emission when incorporated into rigid room-temperature glasses of sucrose octaacetate. Absorption and emission characteristics of the compounds, including luminescence quantum yields, in fluid solution, solution-phase aggregates, and room-temperature glasses are reported. Quantum yields increase by as much as 2 orders of magnitude in the aggregates and glasses, compared to fluid solution. Experimental evidence supports the conclusion that the aggregation-induced enhancement of luminescence results from restricted intramolecular rotations in the packed metalloles. The unusual aggregation-induced enhancement of these compounds makes them potentially useful for the fabrication of a variety of electrooptical devices and sensors. In addition, the X-ray crystal structure of hexaphenylgermole is reported.

  7. Solubility enhancement of simvastatin by arginine: thermodynamics, solute-solvent interactions, and spectral analysis.

    PubMed

    Meor Mohd Affandi, M M R; Tripathy, Minaketan; Shah, Syed Adnan Ali; Majeed, A B A

    2016-01-01

    We examined the solubility of simvastatin in water in 0.01 mol·dm(-3), 0.02 mol·dm(-3), 0.04 mol·dm(-3), 0.09 mol·dm(-3), 0.18 mol·dm(-3), 0.36 mol·dm(-3), and 0.73 mol·dm(-3) arginine (ARG) solutions. The investigated drug is termed the solute, whereas ARG the cosolute. Phase solubility studies illustrated a higher extent of solubility enhancement for simvastatin. The aforementioned system was subjected to conductometric and volumetric measurements at temperatures (T) of 298.15 K, 303.15 K, 308.15 K, and 313.15 K to illustrate the thermodynamics involved and related solute-solvent interactions. The conductance values were used to evaluate the limiting molar conductance and association constants. Thermodynamic parameters (ΔG (0), ΔH (0), ΔS (0), and E s) for the association process of the solute in the aqueous solutions of ARG were calculated. Limiting partial molar volumes and expansibilities were evaluated from the density values. These values are discussed in terms of the solute-solvent and solute-cosolute interactions. Further, these systems were analyzed using ultraviolet-visible analysis, Fourier-transform infrared spectroscopy, and (13)C, (1)H, and two-dimensional nuclear overhauser effect spectroscopy nuclear magnetic resonance to complement thermophysical explanation.

  8. Enhancement of the absorption of CO{sub 2} in alkaline buffer solutions: Joint action of two enhancers

    SciTech Connect

    Vazquez, G.; Chenlo, F.; Pereira, G.; Vazquez, P.

    1999-05-01

    The authors measured the absorption of CO{sub 2} in alkaline 0.5 M/0.5 M sodium carbonate/bicarbonate buffers containing either saccharose and sodium arsenite or saccharose and formaldehyde. Absorption enhancement increased upon increasing the concentration of either of the catalysts, but the joint action of the two was always less than the sum of their individual effects, the difference being a function of the acidities and concentrations of the catalysts and the pH of the carbonate/bicarbonate buffer solution

  9. Yoga Enhances Positive Psychological States in Young Adult Musicians.

    PubMed

    Butzer, Bethany; Ahmed, Khalique; Khalsa, Sat Bir S

    2016-06-01

    Although yoga has been shown to be a viable technique for improving the performance of the mind and body, little attention has been directed to studying the relationship between yoga and the psychological states of flow and mindfulness. Musicians enrolled in a 2-month fellowship program in 2005, 2006 and 2007 were invited to participate in a yoga and meditation program. Fellows not participating in the yoga program were recruited separately as controls. All participants completed baseline and end-program questionnaires evaluating dispositional flow, mindfulness, confusion, and music performance anxiety. Compared to controls, yoga participants reported significant decreases in confusion and increases in dispositional flow. Yoga participants in the 2006 sample also reported significant increases in the mindfulness subscale of awareness. Correlational analyses revealed that increases in participants' dispositional flow and mindfulness were associated with decreases in confusion and music performance anxiety. This study demonstrates the commonalities between positive psychology and yoga, both of which are focused on enhancing human performance and promoting beneficial psychological states. The results suggest that yoga and meditation may enhance the states of flow and mindful awareness, and reduce confusion. PMID:26721471

  10. Mechanism for the Enhanced Excited-State Lewis Acidity of Methyl Viologen.

    PubMed

    Hohenstein, Edward G

    2016-02-17

    Aqueous solutions of methyl viologen (MV(2+)) exhibit anomalous fluorescence behavior. Although it has long fluorescence lifetimes in polar solvents such as acetonitrile, MV(2+) has a short fluorescence lifetime in water. Recent experiments by Kohler and co-workers (Henrich et al. J. Phys. Chem. B 2015, 119, 2737-2748) have implicated an excited-state acid/base reaction as the source of the nonradiative decay pathway. While many chemical species exhibit enhanced Brønsted acidity in their excited state, MV(2+) is the first example of a species with enhanced Lewis acidity. Using a complete active space configuration interaction (CASCI) approach, excited-state molecular dynamics simulations of aqueous MV(2+) are performed in order to test the hypothesis that MV(2+) acts as a Lewis photoacid and to elucidate a mechanism for this behavior. These simulations show that the Lewis acidity of MV(2+) is indeed enhanced by photoexcitation. On its S1 excited state, MV(2+) reacts with water to generate a hydronium ion approximately 1.5 ps after excitation. After the hydronium ion is produced, the corresponding hydroxide ion adds to MV(2+) to form a covalently bound photoproduct and, subsequently, evolves toward a conical intersection.

  11. Enhancement of femtosecond laser-induced nucleation of protein in a gel solution

    NASA Astrophysics Data System (ADS)

    Murai, Ryota; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Maruyama, Mihoko; Sugiyama, Shigeru; Sazaki, Gen; Adachi, Hiroaki; Takano, Kazufumi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke

    2010-01-01

    We found that the use of a gel solution with agarose enhanced femtosecond laser-induced nucleation and produced hen egg white lysozyme crystals at three to five times lower supersaturation than those by the femtosecond laser or agarose alone. The fast fluorescence imaging of the protein in the gel solution revealed that cavitation bubbles created high-concentration regions at the focal point, which could be the trigger for protein nucleation. The lower diffusions of protein molecules in agarose gel retained the high-concentration regions for a longer time, and facilitated the nucleation.

  12. State-based coverage solutions: the California Health Benefit Exchange.

    PubMed

    Weinberg, Micah; Haase, Leif Wellington

    2011-05-01

    California was the first state to create its own health insurance exchange after the passage of the Affordable Care Act. Because of its front-runner status and the sheer size of its coverage expansion, California's choices will have implications for other states as they address difficult issues, including minimizing adverse selection, promoting cost-conscious consumer choice, and seamlessly coordinating with public programs. California took advantage of the flexibility in the federal health reform law to create an exchange that will function as an active purchaser in the marketplace; take significant steps to combat adverse selection both against and within the exchange, including requiring all insurers to sell all tiers of products and making exchange participation a condition of selling catastrophic plans; and allow community-based health plans to develop commercial offerings for the exchange. This brief examines these decisions, which will provide a roadmap for other states as they set up their exchanges. PMID:21630546

  13. Enhancing wastewater reuse by forward osmosis with self-diluted commercial fertilizers as draw solutes.

    PubMed

    Zou, Shiqiang; He, Zhen

    2016-08-01

    Using fertilizers as draw solutes in forward osmosis (FO) can accomplish wastewater reuse with elimination of recycling draw solute. In this study, three commercial fast-release all-purpose solid fertilizers (F1, F2 and F3) were examined as draw solutes in a submerged FO system for water extraction from either deionized (DI) water or the treated wastewater. Systematic optimizations were conducted to enhance water extraction performance, including operation modes, initial draw concentrations and in-situ chemical fouling control. In the mode of the active layer facing the feed (AL-F or FO), a maximum of 324 mL water was harvested using 1-M F1, which provided 41% of the water need for fertilizer dilution for irrigation. Among the three fertilizers, F1 containing a lower urea content was the most favored because of a higher water extraction and a lower reverse solute flux (RSF) of major nutrients. Using the treated wastewater as a feed solution resulted in a comparable water extraction performance (317 mL) to that of DI water in 72 h and a maximum water flux of 4.2 LMH. Phosphorus accumulation on the feed side was mainly due to the FO membrane solute rejection while total nitrogen and potassium accumulation was mainly due to RSF from the draw solute. Reducing recirculation intensity from 100 to 10 mL min(-1) did not obviously decrease water flux but significantly reduced the energy consumption from 1.86 to 0.02 kWh m(-3). These results have demonstrated the feasibility of using commercial solid fertilizers as draw solutes for extracting reusable water from wastewater, and challenges such as reverse solute flux will need to be further addressed. PMID:27174605

  14. Charge-state enhancement for radioactive beam post-acceleration

    SciTech Connect

    Nolen, J.A.; Dooling, J.

    1995-08-01

    A critical question for an ISOL-type radioactive-beam facility, such as that being discussed by the North American Isospin Laboratory Committee, is the efficiency and q/m of the ion source for the radioactive species. ISOLDE at CERN demonstrated that high efficiency is obtained for a wide variety of species in the 1{sup +} charge state. These ion sources also generally have excellent transverse emittances and low energy spreads. One possibility is to use this proven technology plus an ionizer stage to increase the output of such sources to 2, 3, or 4{sup +} with high efficiency. We are currently investigating technical options for such charge-state enhancement. There is a proposal by a Heidelberg/ISOLDE collaboration to build a {open_quotes}charge-state breeder{close_quotes} as part of an experiment called REX-ISOLDE. This concept would deliver batches of radioactive ions with low duty cycle, optimized for relatively low-intensity secondary beams, on the order of 10{sup 6}/sec. We are independently doing simulations of an alternative approach, called the Electron-Beam Charge-State Amplifier (EBQA), which would yield DC beams with improved transverse emittance and would not have the intensity limitation of the batch transfer process. The cost and efficiency of the EBQA will have to be compared with those of a normally-conducting CW RFQ followed by ion stripping, as alternatives for the first stage of a secondary ion accelerator.

  15. VMCast: A VM-Assisted Stability Enhancing Solution for Tree-Based Overlay Multicast.

    PubMed

    Gu, Weidong; Zhang, Xinchang; Gong, Bin; Zhang, Wei; Wang, Lu

    2015-01-01

    Tree-based overlay multicast is an effective group communication method for media streaming applications. However, a group member's departure causes all of its descendants to be disconnected from the multicast tree for some time, which results in poor performance. The above problem is difficult to be addressed because overlay multicast tree is intrinsically instable. In this paper, we proposed a novel stability enhancing solution, VMCast, for tree-based overlay multicast. This solution uses two types of on-demand cloud virtual machines (VMs), i.e., multicast VMs (MVMs) and compensation VMs (CVMs). MVMs are used to disseminate the multicast data, whereas CVMs are used to offer streaming compensation. The used VMs in the same cloud datacenter constitute a VM cluster. Each VM cluster is responsible for a service domain (VMSD), and each group member belongs to a specific VMSD. The data source delivers the multicast data to MVMs through a reliable path, and MVMs further disseminate the data to group members along domain overlay multicast trees. The above approach structurally improves the stability of the overlay multicast tree. We further utilized CVM-based streaming compensation to enhance the stability of the data distribution in the VMSDs. VMCast can be used as an extension to existing tree-based overlay multicast solutions, to provide better services for media streaming applications. We applied VMCast to two application instances (i.e., HMTP and HCcast). The results show that it can obviously enhance the stability of the data distribution.

  16. VMCast: A VM-Assisted Stability Enhancing Solution for Tree-Based Overlay Multicast

    PubMed Central

    Gu, Weidong; Zhang, Xinchang; Gong, Bin; Zhang, Wei; Wang, Lu

    2015-01-01

    Tree-based overlay multicast is an effective group communication method for media streaming applications. However, a group member’s departure causes all of its descendants to be disconnected from the multicast tree for some time, which results in poor performance. The above problem is difficult to be addressed because overlay multicast tree is intrinsically instable. In this paper, we proposed a novel stability enhancing solution, VMCast, for tree-based overlay multicast. This solution uses two types of on-demand cloud virtual machines (VMs), i.e., multicast VMs (MVMs) and compensation VMs (CVMs). MVMs are used to disseminate the multicast data, whereas CVMs are used to offer streaming compensation. The used VMs in the same cloud datacenter constitute a VM cluster. Each VM cluster is responsible for a service domain (VMSD), and each group member belongs to a specific VMSD. The data source delivers the multicast data to MVMs through a reliable path, and MVMs further disseminate the data to group members along domain overlay multicast trees. The above approach structurally improves the stability of the overlay multicast tree. We further utilized CVM-based streaming compensation to enhance the stability of the data distribution in the VMSDs. VMCast can be used as an extension to existing tree-based overlay multicast solutions, to provide better services for media streaming applications. We applied VMCast to two application instances (i.e., HMTP and HCcast). The results show that it can obviously enhance the stability of the data distribution. PMID:26562152

  17. VMCast: A VM-Assisted Stability Enhancing Solution for Tree-Based Overlay Multicast.

    PubMed

    Gu, Weidong; Zhang, Xinchang; Gong, Bin; Zhang, Wei; Wang, Lu

    2015-01-01

    Tree-based overlay multicast is an effective group communication method for media streaming applications. However, a group member's departure causes all of its descendants to be disconnected from the multicast tree for some time, which results in poor performance. The above problem is difficult to be addressed because overlay multicast tree is intrinsically instable. In this paper, we proposed a novel stability enhancing solution, VMCast, for tree-based overlay multicast. This solution uses two types of on-demand cloud virtual machines (VMs), i.e., multicast VMs (MVMs) and compensation VMs (CVMs). MVMs are used to disseminate the multicast data, whereas CVMs are used to offer streaming compensation. The used VMs in the same cloud datacenter constitute a VM cluster. Each VM cluster is responsible for a service domain (VMSD), and each group member belongs to a specific VMSD. The data source delivers the multicast data to MVMs through a reliable path, and MVMs further disseminate the data to group members along domain overlay multicast trees. The above approach structurally improves the stability of the overlay multicast tree. We further utilized CVM-based streaming compensation to enhance the stability of the data distribution in the VMSDs. VMCast can be used as an extension to existing tree-based overlay multicast solutions, to provide better services for media streaming applications. We applied VMCast to two application instances (i.e., HMTP and HCcast). The results show that it can obviously enhance the stability of the data distribution. PMID:26562152

  18. Aqueous solutions of acidic ionic liquids for enhanced stability of polyoxometalate-carbon supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Hu, Chenchen; Zhao, Enbo; Nitta, Naoki; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

    2016-09-01

    Nanocomposites based on polyoxometalates (POMs) nanoconfined in microporous carbons have been synthesized and used as electrodes for supercapacitors. The addition of the pseudocapacitance from highly reversible redox reaction of POMs to the electric double-layer capacitance of carbon lead to an increase in specific capacitance of ∼90% at 1 mV s-1. However, high solubility of POM in traditional aqueous electrolytes leads to rapid capacity fading. Here we demonstrate that the use of aqueous solutions of protic ionic liquids (P-IL) as electrolyte instead of aqueous sulfuric acid solutions offers an opportunity to significantly improve POM cycling stability. Virtually no degradation in capacitance was observed in POM-based positive electrode after 10,000 cycles in an asymmetric capacitor with P-IL aqueous electrolyte. As such, POM-based carbon composites may now present a viable solution for enhancing energy density of electrical double layer capacitors (EDLC) based on pure carbon electrodes.

  19. Engineered Injection and Extraction for Enhanced In-situ Remediation of Sorbing Solutes in Groundwater

    NASA Astrophysics Data System (ADS)

    Webber, B. D.; Neupauer, R. M.; Piscopo, A. N.; Mays, D. C.

    2012-12-01

    Groundwater remediation is becoming increasingly more important as the world's population grows and the necessity of access to clean drinking water persists. The majority of current groundwater treatment methods involve pumping the contaminated groundwater out of the soil and treating it above ground. Sorbed contaminants are difficult to remediate using this conventional pump-and-treat method, and often produce poor treatment results because sorbed contaminants are difficult to extract from the aquifer; therefore in-situ remediation research is of particular importance. One type of in-situ groundwater remediation involves a treatment solution of varying composition being injected into the polluted aquifer to react with the contaminant and degrade it to an acceptable byproduct. Increasing the amount of spreading between the contaminant and the treatment solution promotes an increase in contact area and more desired reactions. It has been previously determined that sequential injection and extraction using four wells for in-situ remediation can enhance the spreading of an aqueous contaminant and treatment solution and increase degradation through more reactions. In this work, we focus on sorbing contaminants and investigate the effectiveness of the injection and extraction methods on varying degrees of contaminant sorption. Tests were conducted in homogeneous and heterogeneous soil media, and with instantaneous and kinetic reaction. It was determined that engineered injection and extraction methods previously developed for aqueous contaminants also enhance in-situ remediation of sorbing solutes.

  20. Ultrafast excited-state deactivation of 9-methylhypoxanthine in aqueous solution: A QM/MM MD study

    NASA Astrophysics Data System (ADS)

    Guo, Xugeng; Yuan, Huijuan; An, Beibei; Zhu, Qiuling; Zhang, Jinglai

    2016-04-01

    Photoinduced ultrafast non-adiabatic decay of 9-methylhypoxanthine (9MHPX) in aqueous solution was investigated by ab initio surface-hopping dynamics calculations using a combined quantum mechanical/molecular mechanical approach. The absorption spectra of 9MHPX in aqueous solution were also explored by the hybrid cluster-continuum model at the level of time-dependent density functional theory along with the polarizable continuum model (PCM). The static electronic-structure calculations indicate that the absorption spectra of 9MHPX simulated by TD-B3LYP/PCM and TD-X3LYP/PCM can reproduce very well the experimental findings, with the accuracy of about 0.20 eV. According to dynamics simulations, irradiation of 9MHPX populates the bright excited singlet S1 state, which may undergo an ultrafast non-radiative deactivation to the S0 state. The lifetime of the S1 state of 9MHPX in aqueous solution is predicted to be 115.6 fs, slightly longer than that in the gas phase (88.8 fs), suggesting that the solvent water has no significant influence on the excited-state lifetime of 9MHPX. Such a behavior in 9MHPX is distinctly different from its parent hypoxanthine keto-N9H tautomer in which the excited-state lifetime of the latter in water solution was remarkably enhanced as compared to the gas phase. The significant difference of the photodynamical behaviors between 9MHPX and keto-N9H can be ascribed to their different hydrogen bond environment in aqueous solution.

  1. Indolic uremic solutes enhance procoagulant activity of red blood cells through phosphatidylserine exposure and microparticle release.

    PubMed

    Gao, Chunyan; Ji, Shuting; Dong, Weijun; Qi, Yushan; Song, Wen; Cui, Debin; Shi, Jialan

    2015-11-01

    Increased accumulation of indolic uremic solutes in the blood of uremic patients contributes to the risk of thrombotic events. Red blood cells (RBCs), the most abundant blood cells in circulation, may be a privileged target of these solutes. However, the effect of uremic solutes indoxyl sulfate (IS) and indole-3-acetic acid (IAA) on procoagulant activity (PCA) of erythrocyte is unclear. Here, RBCs from healthy adults were treated with IS and IAA (mean and maximal concentrations reported in uremic patients). Phosphatidylserine (PS) exposure of RBCs and their microparticles (MPs) release were labeled with Alexa Fluor 488-lactadherin and detected by flow cytometer. Cytosolic Ca(2+) ([Ca(2+)]) with Fluo 3/AM was analyzed by flow cytometer. PCA was assessed by clotting time and purified coagulation complex assays. We found that PS exposure, MPs generation, and consequent PCA of RBCs at mean concentrations of IS and IAA enhanced and peaked in maximal uremic concentrations. Moreover, 128 nM lactadherin, a PS inhibitor, inhibited over 90% PCA of RBCs and RMPs. Eryptosis or damage, by indolic uremic solutes was due to, at least partially, the increase of cytosolic [Ca(2+)]. Our results suggest that RBC eryptosis in uremic solutes IS and IAA plays an important role in thrombus formation through releasing RMPs and exposing PS. Lactadherin acts as an efficient anticoagulant in this process. PMID:26516916

  2. Finite element solution of optimal control problems with state-control inequality constraints

    NASA Technical Reports Server (NTRS)

    Bless, Robert R.; Hodges, Dewey H.

    1992-01-01

    It is demonstrated that the weak Hamiltonian finite-element formulation is amenable to the solution of optimal control problems with inequality constraints which are functions of both state and control variables. Difficult problems can be treated on account of the ease with which algebraic equations can be generated before having to specify the problem. These equations yield very accurate solutions. Owing to the sparse structure of the resulting Jacobian, computer solutions can be obtained quickly when the sparsity is exploited.

  3. Ammonium citrate as enhancement for electrodialytic soil remediation and investigation of soil solution during the process.

    PubMed

    Dias-Ferreira, Celia; Kirkelund, Gunvor M; Ottosen, Lisbeth M

    2015-01-01

    Seven electrodialytic experiments were conducted using ammonium citrate as enhancing agent to remediate copper and chromium-contaminated soil from a wood-preservation site. The purpose was to investigate the effect of current density (0.2, 1.0 and 1.5 mA cm(-2)), concentration of enhancing agent (0.25, 0.5 and 1.0 M) and remediation times (21, 42 and 117 d) for the removal of Cu and Cr from a calcareous soil. To gain insight on metal behavior, soil solution was periodically collected using suction cups. It was seen that current densities higher than 1.0 mA cm(-2) did not increase removal and thus using too high current densities can be a waste of energy. Desorption rate is important and both remediation time and ammonium citrate concentration are relevant parameters. It was possible to collect soil solution samples following an adaptation of the experimental set-up to ensure continuous supply of ammonium citrate to the soil in order to keep it saturated during the remediation. Monitoring soil solution gives valuable information on the evolution of remediation and helps deciding when the soil is remediated. Final concentrations in the soil ranged from 220 to 360 mg Cu kg(-1) (removals: 78-86%) and 440-590 mg Cr kg(-1) (removals: 35-51%), being within the 500 mg kg(-1) limit for a clean soil only for Cu. While further optimization is still required for Cr, the removal percentages are the highest achieved so far, for a real Cu and Cr-contaminated, calcareous soil. The results highlight EDR potential to remediate metal polluted soils at neutral to alkaline pH by choosing a good enhancement solution.

  4. Ammonium citrate as enhancement for electrodialytic soil remediation and investigation of soil solution during the process.

    PubMed

    Dias-Ferreira, Celia; Kirkelund, Gunvor M; Ottosen, Lisbeth M

    2015-01-01

    Seven electrodialytic experiments were conducted using ammonium citrate as enhancing agent to remediate copper and chromium-contaminated soil from a wood-preservation site. The purpose was to investigate the effect of current density (0.2, 1.0 and 1.5 mA cm(-2)), concentration of enhancing agent (0.25, 0.5 and 1.0 M) and remediation times (21, 42 and 117 d) for the removal of Cu and Cr from a calcareous soil. To gain insight on metal behavior, soil solution was periodically collected using suction cups. It was seen that current densities higher than 1.0 mA cm(-2) did not increase removal and thus using too high current densities can be a waste of energy. Desorption rate is important and both remediation time and ammonium citrate concentration are relevant parameters. It was possible to collect soil solution samples following an adaptation of the experimental set-up to ensure continuous supply of ammonium citrate to the soil in order to keep it saturated during the remediation. Monitoring soil solution gives valuable information on the evolution of remediation and helps deciding when the soil is remediated. Final concentrations in the soil ranged from 220 to 360 mg Cu kg(-1) (removals: 78-86%) and 440-590 mg Cr kg(-1) (removals: 35-51%), being within the 500 mg kg(-1) limit for a clean soil only for Cu. While further optimization is still required for Cr, the removal percentages are the highest achieved so far, for a real Cu and Cr-contaminated, calcareous soil. The results highlight EDR potential to remediate metal polluted soils at neutral to alkaline pH by choosing a good enhancement solution. PMID:25240953

  5. Positive periodic solutions for a neutral Lotka-Volterra system with state dependent delays

    NASA Astrophysics Data System (ADS)

    Li, Yongkun; Zhao, Lili

    2009-04-01

    By using a fixed point theorem of strict-set-contraction, some new criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with state dependent delays

  6. The bound state solution for the Morse potential with a localized mass profile

    NASA Astrophysics Data System (ADS)

    Miraboutalebi, S.

    2016-10-01

    We investigate an analytical solution for the Schrödinger equation with a position-dependent mass distribution, with the Morse potential via Laplace transformations. We considered a mass function localized around the equilibrium position. The mass distribution depends on the energy spectrum of the state and the intrinsic parameters of the Morse potential. An exact bound state solution is obtained in the presence of this mass distribution.

  7. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to ·OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to ·OH, electro-reduction of O3 to ·OH at the cathode, and O3 decomposition to ·OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process.

  8. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to ·OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to ·OH, electro-reduction of O3 to ·OH at the cathode, and O3 decomposition to ·OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process. PMID:25989593

  9. Discontinuous steady-state analytical solutions of the Boussinesq equation and their numerical representation by MODFLOW.

    PubMed

    Zaidel, Jacob

    2013-01-01

    Known analytical solutions of groundwater flow equations are routinely used for verification of computer codes. However, these analytical solutions (e.g., the Dupuit solution for the steady-state unconfined unidirectional flow in a uniform aquifer with a flat bottom) represent smooth and continuous water table configurations, simulating which does not pose any significant problems for the numerical groundwater flow models, like MODFLOW. One of the most challenging numerical cases for MODFLOW arises from drying-rewetting problems often associated with abrupt changes in the elevations of impervious base of a thin unconfined aquifer. Numerical solutions of groundwater flow equations cannot be rigorously verified for such cases due to the lack of corresponding exact analytical solutions. Analytical solutions of the steady-state Boussinesq equation, associated with the discontinuous water table configurations over a stairway impervious base, are presented in this article. Conditions resulting in such configurations are analyzed and discussed. These solutions appear to be well suited for testing and verification of computer codes. Numerical solutions, obtained by the latest versions of MODFLOW (MODFLOW-2005 and MODFLOW-NWT), are compared with the presented discontinuous analytical solutions. It is shown that standard MODFLOW-2005 code (as well as MODFLOW-2000 and older versions) has significant convergence problems simulating such cases. The problems manifest themselves either in a total convergence failure or erroneous results. Alternatively, MODFLOW-NWT, providing a good match to the presented discontinuous analytical solutions, appears to be a more reliable and appropriate code for simulating abrupt changes in water table elevations.

  10. Glucose enhancement of memory is not state-dependent.

    PubMed

    Kopf, S R; Opezzo, J W; Baratti, C M

    1993-11-01

    Immediate post-training intraperitoneal administration of alpha-D[+]-glucose (10-300 mg/kg) significantly enhanced retention of male Swiss mice tested 24 h after training in an inhibitory avoidance task. The dose-response curve was an inverted U in this range of dose. However, of the doses tested, only 30 mg/kg was effective. Glucose did not affect response latencies in mice not given the footshock on the training trial, suggesting that the actions of glucose on retention performance were not due to nonspecific effects on response latencies. The influence of glucose (30 mg/kg) was time-dependent, which suggests that glucose facilitated memory consolidation processes. Administration of glucose (30 mg/kg) 2 or 10 min prior to the retention test did not affect the retention performance of mice given post-training injections of either saline or glucose (30 mg/kg). These findings indicate that the memory-enhancing effects of post-training administration of glucose are not state-dependent and are consistent with the view that the behavioral effects of glucose are mediated through an interaction with the neural or neurohumoral processes underlying the storage of acquired information. PMID:8297314

  11. Glucose enhancement of memory is not state-dependent.

    PubMed

    Kopf, S R; Opezzo, J W; Baratti, C M

    1993-11-01

    Immediate post-training intraperitoneal administration of alpha-D[+]-glucose (10-300 mg/kg) significantly enhanced retention of male Swiss mice tested 24 h after training in an inhibitory avoidance task. The dose-response curve was an inverted U in this range of dose. However, of the doses tested, only 30 mg/kg was effective. Glucose did not affect response latencies in mice not given the footshock on the training trial, suggesting that the actions of glucose on retention performance were not due to nonspecific effects on response latencies. The influence of glucose (30 mg/kg) was time-dependent, which suggests that glucose facilitated memory consolidation processes. Administration of glucose (30 mg/kg) 2 or 10 min prior to the retention test did not affect the retention performance of mice given post-training injections of either saline or glucose (30 mg/kg). These findings indicate that the memory-enhancing effects of post-training administration of glucose are not state-dependent and are consistent with the view that the behavioral effects of glucose are mediated through an interaction with the neural or neurohumoral processes underlying the storage of acquired information.

  12. [Fluorescence enhancement of flavoxate hydrochloride in alkali solution and its application in pharmaceutical analysis].

    PubMed

    Li, Wen-hong; Sun, Chong-mei; Wei, Yong-ju

    2015-10-01

    Fluorescence enhancement reaction of flavoxate hydrochloride (FX) in strong alkali solution was studied, the mechanism of the reaction was investigated, and a novel fluorimetric method for analysis of FX in drug sample was established. FX has no intrinsic fluorescence, but it can slowly produce fluorescence in strong alkali solution. Heating can promote the fluorescence enhancement reaction. In 3D fluorescence spectra of the decomposition product of FX, two fluorescence peaks, located respectively at excitation wavelengths λex/ emission wavelength λem =223/410 nm, and 302/410 nm, were observed. Using quinine sulfate as a reference, fluorescence quantum yield of the decomposition product was measured to be 0.50. The structural characteriza- tion and spectral analysis of the decomposition product reveal that ester bond hydrolysis reaction of FX is firstly occurred during heating process, forming 3-methylflavone-8-carboxylic acid (MFA), then a cleavage reaction of the γ-pyrone ring of MFA occurred, producing α, β-unsaturated ketone. This product includes adjacent hydroxyl benzoic acid group in its molecule, which can form intramolecular hydrogen bond under alkaline condition, so that increase the conjugate degree and enhance the rigidity of the molecule, and thereby cause fluorescence enhancement. Based on this fluorescence enhancement reaction, a fluorimetric method was proposed for the determination of FX. A linear calibration curve covered the concentration range 0.020 3-0.487 µg · mL. The regression equation was I(F) = 23.9 + 5357.3 c, with correlation coefficient r = 0.999 7 (n = 8), detection limit D = 1.1 ng · mL(-1). The method was applied to the analysis of FX tablets, with a spiked recovery rate of 100.2%. The reliability of the method was verified by a UV-spectrophotometric method.

  13. [Fluorescence enhancement of flavoxate hydrochloride in alkali solution and its application in pharmaceutical analysis].

    PubMed

    Li, Wen-hong; Sun, Chong-mei; Wei, Yong-ju

    2015-10-01

    Fluorescence enhancement reaction of flavoxate hydrochloride (FX) in strong alkali solution was studied, the mechanism of the reaction was investigated, and a novel fluorimetric method for analysis of FX in drug sample was established. FX has no intrinsic fluorescence, but it can slowly produce fluorescence in strong alkali solution. Heating can promote the fluorescence enhancement reaction. In 3D fluorescence spectra of the decomposition product of FX, two fluorescence peaks, located respectively at excitation wavelengths λex/ emission wavelength λem =223/410 nm, and 302/410 nm, were observed. Using quinine sulfate as a reference, fluorescence quantum yield of the decomposition product was measured to be 0.50. The structural characteriza- tion and spectral analysis of the decomposition product reveal that ester bond hydrolysis reaction of FX is firstly occurred during heating process, forming 3-methylflavone-8-carboxylic acid (MFA), then a cleavage reaction of the γ-pyrone ring of MFA occurred, producing α, β-unsaturated ketone. This product includes adjacent hydroxyl benzoic acid group in its molecule, which can form intramolecular hydrogen bond under alkaline condition, so that increase the conjugate degree and enhance the rigidity of the molecule, and thereby cause fluorescence enhancement. Based on this fluorescence enhancement reaction, a fluorimetric method was proposed for the determination of FX. A linear calibration curve covered the concentration range 0.020 3-0.487 µg · mL. The regression equation was I(F) = 23.9 + 5357.3 c, with correlation coefficient r = 0.999 7 (n = 8), detection limit D = 1.1 ng · mL(-1). The method was applied to the analysis of FX tablets, with a spiked recovery rate of 100.2%. The reliability of the method was verified by a UV-spectrophotometric method. PMID:26837181

  14. State-constrained booster trajectory solutions via finite elements and shooting

    NASA Technical Reports Server (NTRS)

    Bless, Robert R.; Hodges, Dewey H.; Seywald, Hans

    1993-01-01

    This paper presents an extension of a FEM formulation based on variational principles. A general formulation for handling internal boundary conditions and discontinuities in the state equations is presented, and the general formulation is modified for optimal control problems subject to state-variable inequality constraints. Solutions which only touch the state constraint and solutions which have a boundary arc of finite length are considered. Suitable shape and test functions are chosen for a FEM discretization. All element quadrature (equivalent to one-point Gaussian quadrature over each element) may be done in closed form. The final form of the algebraic equations is then derived. A simple state-constrained problem is solved. Then, for a practical application of the use of the FEM formulation, a launch vehicle subject to a dynamic pressure constraint (a first-order state inequality constraint) is solved. The results presented for the launch-vehicle trajectory have some interesting features, including a touch-point solution.

  15. Quantum Dot Light Enhancement Substrate for OLED Solid-State Lighting

    SciTech Connect

    James Perkins; Matthew Stevenson; Gagan Mahan; Seth Coe-Sullivan; Peter Kazlas

    2011-01-21

    With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitive solution for increasing the light extraction efficiency of OLEDs with efficient and stable color rendering index (CRI) for solid state lighting (SSL). Solution processable quantum dot (QD) films were integrated into OLED ITO-glass substrates to generate tunable white emission from blue emitting OLED) devices as well as outcouple light from the ITO film. This QD light-enhancement substrate (QD-LED) technology demonstrated a 60% increase in OLED forward light out-coupling, a value which increases to 76% when considering total increase in multi-directional light output. The objective for the first year was an 80% increase in light output. This project seeks to develop and demonstrate a cost-competitive solution for realizing increased extraction efficiency organic light emitting devices (OLEDs) with efficient and stable color rendering index (CRI) for SSL. Solution processible quantum dot (QD) films will be utilized to generate tunable white emission from blue emitting phosphorescent OLED (Ph-OLED) devices.

  16. PROCESS OF SECURING PLUTONIUM IN NITRIC ACID SOLUTIONS IN ITS TRIVALENT OXIDATION STATE

    DOEpatents

    Thomas, J.R.

    1958-08-26

    >Various processes for the recovery of plutonium require that the plutonium be obtalned and maintained in the reduced or trivalent state in solution. Ferrous ions are commonly used as the reducing agent for this purpose, but it is difficult to maintain the plutonium in a reduced state in nitric acid solutions due to the oxidizing effects of the acid. It has been found that the addition of a stabilizing or holding reductant to such solution prevents reoxidation of the plutonium. Sulfamate ions have been found to be ideally suitable as such a stabilizer even in the presence of nitric acid.

  17. Integrating matrix solution of the hybrid state vector equations for beam vibration

    NASA Technical Reports Server (NTRS)

    Lehman, L. L.

    1982-01-01

    A simple, versatile, and efficient computational technique has been developed for dynamic analysis of linear elastic beam and rod type of structures. Moreover, the method provides a rather general solution approach for two-point boundary value problems that are described by a single independent spatial variable. For structural problems, the method is implemented by a mixed state vector formulation of the differential equations, combined with an integrating matrix solution procedure. Highly accurate solutions are easily achieved with this approach. Example solutions are given for beam vibration problems including discontinuous stiffness and mass parameters, elastic restraint boundary conditions, concentrated inertia loading, and rigid body modes

  18. Solution of steady-state one-dimensional conservation laws by mathematical programming

    NASA Technical Reports Server (NTRS)

    Lavery, J. E.

    1989-01-01

    Solution techniques for a class of steady-state scalar conservation laws are developed analytically. Discretization by finite-volume formulas is employed to obtain an overdetermined system of algebraic equations, which are then perturbed nonsingularly (with perturbation coefficient = epsilon) and solved using the l(1) mathematical-programming algorithm of Seneta and Steiger (1984); this approach limits the matrix bandwidth to two, so that an explicit solution can be found efficiently. It is shown that, for small values of epsilon, the l(1) solutions exhibit sharp correctly located shocks and are nonoscillatory O(epsilon) approximations of the physically relevant solutions.

  19. Resolution enhanced T1-insensitive steady-state imaging.

    PubMed

    Derakhshan, Jamal J; Nour, Sherif G; Sunshine, Jeffrey L; Griswold, Mark A; Duerk, Jeffrey L

    2012-08-01

    Resolution enhanced T(1)-insensitive steady-state imaging (RE-TOSSI) is a new MRI pulse sequence for the generation of rapid T(2) contrast with high spatial resolution. TOSSI provides T(2) contrast by using nonequally spaced inversion pulses throughout a balanced steady-state free precession (SSFP) acquisition. In RE-TOSSI, these energy and time intensive adiabatic inversion pulses and associated magnetization preparation are removed from TOSSI after acquisition of the data around the center of k-space. Magnetization evolution simulations demonstrate T(2) contrast in TOSSI as well as reduction in the widening of the point spread function width (by up to a factor of 4) to a near ideal case for RE-TOSSI. Phantom experimentation is used to characterize and compare the contrast and spatial resolution properties of TOSSI, RE-TOSSI, balanced SSFP, Half-Fourier Acquisition Single-Shot Turbo Spin Echo (HASTE), and turbo spin echo and to optimize the fraction of k-space acquired using TOSSI. Comparison images in the abdomen and brain demonstrate similar contrast and improved spatial resolution in RE-TOSSI compared with TOSSI; comparison balanced SSFP, HASTE, and turbo spin echo images are provided. RE-TOSSI is capable of providing high spatial resolution T(2)-weighted images in 1 s or less per image.

  20. Mathematical analysis of steady-state solutions in compartment and continuum models of cell polarization.

    PubMed

    Zheng, Zhenzhen; Chou, Ching-Shan; Yi, Tau-Mu; Nie, Qing

    2011-10-01

    Cell polarization, in which substances previously uniformly distributed become asymmetric due to external or/and internal stimulation, is a fundamental process underlying cell mobility, cell division, and other polarized functions. The yeast cell S. cerevisiae has been a model system to study cell polarization. During mating, yeast cells sense shallow external spatial gradients and respond by creating steeper internal gradients of protein aligned with the external cue. The complex spatial dynamics during yeast mating polarization consists of positive feedback, degradation, global negative feedback control, and cooperative effects in protein synthesis. Understanding such complex regulations and interactions is critical to studying many important characteristics in cell polarization including signal amplification, tracking dynamic signals, and potential trade-off between achieving both objectives in a robust fashion. In this paper, we study some of these questions by analyzing several models with different spatial complexity: two compartments, three compartments, and continuum in space. The step-wise approach allows detailed characterization of properties of the steady state of the system, providing more insights for biological regulations during cell polarization. For cases without membrane diffusion, our study reveals that increasing the number of spatial compartments results in an increase in the number of steady-state solutions, in particular, the number of stable steady-state solutions, with the continuum models possessing infinitely many steady-state solutions. Through both analysis and simulations, we find that stronger positive feedback, reduced diffusion, and a shallower ligand gradient all result in more steady-state solutions, although most of these are not optimally aligned with the gradient. We explore in the different settings the relationship between the number of steady-state solutions and the extent and accuracy of the polarization. Taken together

  1. Enhancement of anammox activity by addition of compatible solutes at high salinity conditions.

    PubMed

    Liu, Mu; Peng, Yongzhen; Wang, Shuying; Liu, Tiantian; Xiao, Han

    2014-09-01

    The enhancement effect of compatible solutes on anammox activity under salinity stress was investigated. Glycine betaine (GB) was the most effective in alleviating salt toxicity, although all the compatible solutes (GB, trehalose and ectoine) were found to be valid. Acclimation potential of anammox biomass under salinity of 30 g/L increased significantly with GB addition. The recovery time in the reactor with GB addition (RB) (49 days) accompanied by a more stable stoichiometric ratio was 2.65 times shorter than in the control reactor (RC) (130 days). After 49 days, the extracellular polymeric substances and the tetrazolium chloride-dehydrogenase activity were 217.9 mg/g VSS and 38.7 μg TF/g VSS/h in RB, 1.86 times lower and 3.17 times higher than the levels in RC, respectively. RB possessed evident superiority in the aspects of microbial population proportion. And thus, compatible solutes addition was regarded as one of the feasible solution to counteract saline inhibition on anammox. PMID:25024098

  2. Enhanced sorption of polycyclic aromatic hydrocarbons from aqueous solution by modified pine bark.

    PubMed

    Li, Yungui; Chen, Baoliang; Zhu, Lizhong

    2010-10-01

    To enhance removal efficiency of natural sorbent with polycyclic aromatic hydrocarbons (PAHs), single-solute and bi-solute sorption of phenanthrene and pyrene onto raw and modified pine bark were investigated. Pine bark was modified using Soxhlet extraction, saponification and acid hydrolysis, yielding six bark fractions with different chemical compositions. Raw pine bark exhibited high affinities with PAHs, and sorption was dominated by partitioning. The relatively nonlinear sorption isotherms of modified bark were attributed to the specific interaction between sorbate and aromatic core of sorbent. Comparison with lipid and suberin, lignin was the most powerful sorption medium, but which was almost completely suppressed by coexisting polysaccharide. After consuming polysaccharide by acid hydrolysis, sorption of pine bark fractions was notably increased (4-17 folds); and sorption of pyrene just decreased 16-34% with phenanthrene as a competitor. These observations suggest that pine bark is of great potential for PAHs removal and can be significantly promoted by acid hydrolysis for environmental application.

  3. Flow-enhanced solution printing of all-polymer solar cells.

    PubMed

    Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; Shaw, Leo; Wang, Cheng; Park, Steve; Guo, Yikun; Reinspach, Julia A; Gu, Kevin; Gu, Xiaodan; Tee, Benjamin C K; Pang, Changhyun; Yan, Hongping; Zhao, Dahui; Toney, Michael F; Mannsfeld, Stefan C B; Bao, Zhenan

    2015-08-12

    Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a ∼90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. We expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility.

  4. Flow-enhanced solution printing of all-polymer solar cells

    SciTech Connect

    Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; Shaw, Leo; Wang, Cheng; Park, Steve; Guo, Yikun; Reinspach, Julia A.; Gu, Kevin; Gu, Xiaodan; Tee, Benjamin C. K.; Pang, Changhyun; Yan, Hongping; Zhao, Dahui; Toney, Michael F.; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2015-08-12

    Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a similar to 90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. However, we expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility.

  5. Flow-enhanced solution printing of all-polymer solar cells

    PubMed Central

    Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; Shaw, Leo; Wang, Cheng; Park, Steve; Guo, Yikun; Reinspach, Julia A.; Gu, Kevin; Gu, Xiaodan; Tee, Benjamin C. K.; Pang, Changhyun; Yan, Hongping; Zhao, Dahui; Toney, Michael F.; Mannsfeld, Stefan C. B.; Bao, Zhenan

    2015-01-01

    Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a ∼90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhanced all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. We expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility. PMID:26264528

  6. Analytical solution of the heat equation in a longitudinally pumped cubic solid-state laser.

    PubMed

    Sabaeian, Mohammad; Nadgaran, Hamid; Mousave, Laleh

    2008-05-01

    Knowledge about the temperature distribution inside solid-state laser crystals is essential for calculation of thermal phase shift, thermal lensing, thermally induced birefringence, and heat-induced crystal bending. Solutions for the temperature distribution for the case of steady-state heat loading have appeared in the literature only for simple cylindrical crystal shapes and are usually based on numerical techniques. For the first time, to our knowledge, a full analytical solution of the heat equation for an anisotropic cubic cross-section solid-state crystal is presented. The crystal is assumed to be longitudinally pumped by a Gaussian pump profile. The pump power attenuation along the crystal and the real cooling mechanisms, such as convection, are considered in detail. A comparison between our analytical solutions and its numerical counterparts shows excellent agreement when just a few terms are employed in the series solutions.

  7. Analytical solution of the heat equation in a longitudinally pumped cubic solid-state laser

    SciTech Connect

    Sabaeian, Mohammad; Nadgaran, Hamid; Mousave, Laleh

    2008-05-01

    Knowledge about the temperature distribution inside solid-state laser crystals is essential for calculation of thermal phase shift, thermal lensing, thermally induced birefringence, and heat-induced crystal bending. Solutions for the temperature distribution for the case of steady-state heat loading have appeared in the literature only for simple cylindrical crystal shapes and are usually based on numerical techniques. For the first time, to our knowledge, a full analytical solution of the heat equation for an anisotropic cubic cross-section solid-state crystal is presented. The crystal is assumed to be longitudinally pumped by a Gaussian pump profile. The pump power attenuation along the crystal and the real cooling mechanisms, such as convection, are considered in detail. A comparison between our analytical solutions and its numerical counterparts shows excellent agreement when just a few terms are employed in the series solutions.

  8. On the accuracy of limiters and convergence to steady state solutions

    NASA Technical Reports Server (NTRS)

    Venkatakrishnan, V.

    1993-01-01

    This paper addresses the practical problem of obtaining convergence to steady state solutions when limiters are used in conjunction with upwind schemes on unstructured grids. The base scheme forms a gradient and limits it by imposing monotonicity conditions in the reconstruction stage. It is shown by analysis in one dimension that such an approach leads to various schemes meeting TVD requirements in one dimension. It is further shown that these formally second order accurate schemes are less than second order accurate in practice because of the action of the limiter function in smooth regions of the solution. Modifications are proposed to the limiter that restore the second order accuracy. In multiple dimensions these schemes produce steady state solutions that are monotone and devoid of oscillations. However, convergence stalls after a few orders of reduction in the residual. With the modified limiter, on the other hand, it is shown that converged steady state solutions can be obtained.

  9. Ultrafast excited-state deactivation of 9-methylhypoxanthine in aqueous solution: A QM/MM MD study.

    PubMed

    Guo, Xugeng; Yuan, Huijuan; An, Beibei; Zhu, Qiuling; Zhang, Jinglai

    2016-04-21

    Photoinduced ultrafast non-adiabatic decay of 9-methylhypoxanthine (9MHPX) in aqueous solution was investigated by ab initio surface-hopping dynamics calculations using a combined quantum mechanical/molecular mechanical approach. The absorption spectra of 9MHPX in aqueous solution were also explored by the hybrid cluster-continuum model at the level of time-dependent density functional theory along with the polarizable continuum model (PCM). The static electronic-structure calculations indicate that the absorption spectra of 9MHPX simulated by TD-B3LYP/PCM and TD-X3LYP/PCM can reproduce very well the experimental findings, with the accuracy of about 0.20 eV. According to dynamics simulations, irradiation of 9MHPX populates the bright excited singlet S1 state, which may undergo an ultrafast non-radiative deactivation to the S0 state. The lifetime of the S1 state of 9MHPX in aqueous solution is predicted to be 115.6 fs, slightly longer than that in the gas phase (88.8 fs), suggesting that the solventwater has no significant influence on the excited-state lifetime of 9MHPX. Such a behavior in 9MHPX is distinctly different from its parent hypoxanthine keto-N9H tautomer in which the excited-state lifetime of the latter in watersolution was remarkably enhanced as compared to the gas phase. The significant difference of the photodynamical behaviors between 9MHPX and keto-N9H can be ascribed to their different hydrogen bond environment in aqueous solution. PMID:27389219

  10. Stability of curcumin in different solvent and solution media: UV-visible and steady-state fluorescence spectral study.

    PubMed

    Mondal, Satyajit; Ghosh, Soumen; Moulik, Satya P

    2016-05-01

    In aqueous solution, curcumin is photodegradable (light sensitive), it is also self-degradable in the dark. In basic medium, the second process is enhanced. The dark process has been studied in water and also in a number of protic and aprotic solvents, and aqueous solutions of ionic liquids, pluronics, reverse micelles and salt. The kinetics of the process followed the first order rate law; a comparative as well as individual assessment of which has been made. The kinetics of curcumin self-degradation has been found to be fairly dependent on salt (NaCl) concentration. Curcumin molecules in solution may remain in the enol or keto-enol form. From the visible spectral analysis, an estimate of the proportions of these forms in aqueous ethanol medium has been made. The temperature effect on the visible and fluorescence spectra of curcumin has been also studied. The steady state fluorescence anisotropy of the photoactive curcumin has been evaluated in different solvent and solution media. The reversibility of the steady state fluorescence anisotropy of curcumin on heating and cooling conditions has been examined. The results herein presented are new and ought to be useful as the study of physicochemistry of curcumin has been gaining importance in the light of its biological importance. PMID:26985735

  11. Outbreaks caused by sprouts, United States, 1998-2010: lessons learned and solutions needed.

    PubMed

    Dechet, Amy M; Herman, Karen M; Chen Parker, Cary; Taormina, Peter; Johanson, Joy; Tauxe, Robert V; Mahon, Barbara E

    2014-08-01

    After a series of outbreaks associated with sprouts in the mid-1990s, the U.S. Food and Drug Administration (FDA) published guidelines in 1999 for sprouts producers to reduce the risk of contamination. The recommendations included treating seeds with an antimicrobial agent such as calcium hypochlorite solution and testing spent irrigation water for pathogens. From 1998 through 2010, 33 outbreaks from seed and bean sprouts were documented in the United States, affecting 1330 reported persons. Twenty-eight outbreaks were caused by Salmonella, four by Shiga toxin-producing Escherichia coli, and one by Listeria. In 15 of the 18 outbreaks with information available, growers had not followed key FDA guidelines. In three outbreaks, however, the implicated sprouts were produced by firms that appeared to have implemented key FDA guidelines. Although seed chlorination, if consistently applied, reduces pathogen burden on sprouts, it does not eliminate the risk of human infection. Further seed and sprouts disinfection technologies, some recently developed, will be needed to enhance sprouts safety and reduce human disease. Improved seed production practices could also decrease pathogen burden but, because seeds are a globally distributed commodity, will require international cooperation. PMID:25076040

  12. A simple solution for antibody signal enhancement in immunofluorescence and triple immunogold assays.

    PubMed

    Rosas-Arellano, Abraham; Villalobos-González, Juan B; Palma-Tirado, Lourdes; Beltrán, Felipe A; Cárabez-Trejo, Alfonso; Missirlis, Fanis; Castro, Maite A

    2016-10-01

    Immunolocalization techniques are standard in biomedical research. Tissue fixation with aldehydes and cell membrane permeabilization with detergents can distort the specific binding of antibodies to their high affinity epitopes. In immunofluorescence protocols, it is desirable to quench the sample's autofluorescence without reduction of the antibody-dependent signal. Here we show that adding glycine to the blocking buffer and diluting the antibodies in a phosphate saline solution containing glycine, Triton X-100, Tween20 and hydrogen peroxide increase the specific antibody signal in tissue immunofluorescence and immunogold electron microscopy. This defined antibody signal enhancer (ASE) solution gives similar results to the commercially available Pierce Immunostain Enhancer (PIE). Furthermore, prolonged tissue incubation in resin and fixative and application of ASE or PIE are described in an improved protocol for triple immunogold electron microscopy that is used to show co-localization of GABA-A ρ2 and dopamine D2 receptors in GFAP-positive astrocytes in the mouse striatum. The addition of glycine, Triton X-100, Tween20 and hydrogen peroxide during antibody incubation steps is recommended in immunohistochemistry methods.

  13. Enhanced soil washing of phenanthrene by mixed solutions of TX100 and SDBS.

    PubMed

    Yang, Kun; Zhu, Lizhong; Xing, Baoshan

    2006-07-01

    Increased desorption of hydrophobic organic compounds (HOCs) from soils and sediments is a key to the remediation of contaminated soils and groundwater. In this study, phenanthrene desorption from a contaminated soil by mixed solutions of a nonionic surfactant(octylphenol polyethoxylate, TX100) and an anionic surfactant (sodium dodecylbenzenesulfonate, SDBS) was investigated. Phenanthrene desorption depended on not only aqueous surfactant concentrations and phenanthrene solubility enhancement but also the soil-sorbed surfactant amount and the corresponding sorption capacity of sorbed surfactants. The added surfactant critical desorption concentrations (CDCs) for phenanthrene from soil depended on both sorbed concentrations of surfactants and their critical micelle concentrations (CMCs). Phenanthrene desorption by mixed solutions was more efficient than individual surfactants due to the low sorption loss of mixed surfactants to soil. Among the tested surfactant systems, mixed TX100 and SDBS with a 1:9 mass ratio exhibited the highest phenanthrene desorption. Mixed micelle formation, showing negative deviation of CMCs from the ones predicted by the ideal mixing theory, was primarily responsible for the significant reduction of soil-sorbed amounts of TX100 and SDBS in their mixed systems. Therefore, mixed anionic-nonionic surfactants had great potential in the area of enhanced soil and groundwater remediation.

  14. Enhanced solid-state metathesis routes to carbon nanotubes.

    PubMed

    Mack, Julia J; Tari, Susanne; Kaner, Richard B

    2006-05-15

    Ignition of three solids creates multiwalled carbon nanotubes in seconds. A solid-state metathesis (exchange) reaction between hexachloroethane (C2Cl6) and lithium acetylide (Li2C2) with 5% cobalt dichloride (CoCl2) added as an initiator produces up to 7% carbon nanotubes, as observed via transmission electron microscopy. Using the concept that sulfur can promote nanotube growth, the reaction yield can be increased to 15% by switching to CoS as the initiator. The more readily available, inexpensive calcium carbide (CaC2) can be substituted for lithium acetylide while maintaining comparable yields. Switching initiators to FeS can be used to further enhance the yield. A systematic study of the C2Cl6/CaC2 reaction system indicates that a yield up to 25% can be realized by using 6% FeS as the initiator. Reaction temperatures for the C(2)Cl6/CaC2 system of up to 3550 degrees C are calculated using thermodynamic data assuming quantitative yield and adiabatic conditions.

  15. Billion-fold enhancement in sensitivity of nuclear magnetic resonance spectroscopy for magnesium ions in solution.

    PubMed

    Gottberg, Alexander; Stachura, Monika; Kowalska, Magdalena; Bissell, Mark L; Arcisauskaite, Vaida; Blaum, Klaus; Helmke, Alexander; Johnston, Karl; Kreim, Kim; Larsen, Flemming H; Neugart, Rainer; Neyens, Gerda; Garcia Ruiz, Ronald F; Szunyogh, Daniel; Thulstrup, Peter W; Yordanov, Deyan T; Hemmingsen, Lars

    2014-12-15

    β-nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β-NMR has previously been successfully applied in the fields of nuclear and solid-state physics. In this work, β-NMR is applied, for the first time, to record an NMR spectrum for a species in solution. (31)Mg β-NMR spectra are measured for as few as 10(7) magnesium ions in ionic liquid (EMIM-Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β-NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry.

  16. Billion-fold enhancement in sensitivity of nuclear magnetic resonance spectroscopy for magnesium ions in solution.

    PubMed

    Gottberg, Alexander; Stachura, Monika; Kowalska, Magdalena; Bissell, Mark L; Arcisauskaite, Vaida; Blaum, Klaus; Helmke, Alexander; Johnston, Karl; Kreim, Kim; Larsen, Flemming H; Neugart, Rainer; Neyens, Gerda; Garcia Ruiz, Ronald F; Szunyogh, Daniel; Thulstrup, Peter W; Yordanov, Deyan T; Hemmingsen, Lars

    2014-12-15

    β-nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β-NMR has previously been successfully applied in the fields of nuclear and solid-state physics. In this work, β-NMR is applied, for the first time, to record an NMR spectrum for a species in solution. (31)Mg β-NMR spectra are measured for as few as 10(7) magnesium ions in ionic liquid (EMIM-Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β-NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry. PMID:25303164

  17. Numerical solution of a coupled pair of elliptic equations from solid state electronics

    NASA Technical Reports Server (NTRS)

    Phillips, T. N.

    1983-01-01

    Iterative methods are considered for the solution of a coupled pair of second order elliptic partial differential equations which arise in the field of solid state electronics. A finite difference scheme is used which retains the conservative form of the differential equations. Numerical solutions are obtained in two ways, by multigrid and dynamic alternating direction implicit methods. Numerical results are presented which show the multigrid method to be an efficient way of solving this problem.

  18. Infinite product expansion of the Fokker–Planck equation with steady-state solution

    PubMed Central

    Martin, R. J.; Craster, R. V.; Kearney, M. J.

    2015-01-01

    We present an analytical technique for solving Fokker–Planck equations that have a steady-state solution by representing the solution as an infinite product rather than, as usual, an infinite sum. This method has many advantages: automatically ensuring positivity of the resulting approximation, and by design exactly matching both the short- and long-term behaviour. The efficacy of the technique is demonstrated via comparisons with computations of typical examples. PMID:26346100

  19. Anti-periodic solutions of Liénard equations with state dependent impulses

    NASA Astrophysics Data System (ADS)

    Belley, J.-M.; Bondo, É.

    2016-10-01

    Subject to a priori bounds, Liénard equations with state dependent impulsive forcing are shown to admit a unique absolutely continuous anti-periodic solution with first derivative of bounded variation on finite intervals. The point-wise convergence of a sequence of iterates to the solution is obtained, along with a bound for the rate of convergence. The results are applied to Josephson's and van der Pol's equations.

  20. Approximate semi-analytical solutions for the steady-state expansion of a contactor plasma

    NASA Astrophysics Data System (ADS)

    Camporeale, E.; Hogan, E. A.; MacDonald, E. A.

    2015-04-01

    We study the steady-state expansion of a collisionless, electrostatic, quasi-neutral plasma plume into vacuum, with a fluid model. We analyze approximate semi-analytical solutions, that can be used in lieu of much more expensive numerical solutions. In particular, we focus on the earlier studies presented in Parks and Katz (1979 American Institute of Aeronautics, Astronautics Conf. vol 1), Korsun and Tverdokhlebova (1997 33rd Joint Prop. Conf. (Seattle, WA) AIAA-97-3065), and Ashkenazy and Fruchtman (2001 27th Int. Electric Propulsion Conf. (Pasadena, CA)). By calculating the error with respect to the numerical solution, we can judge the range of validity for each solution. Moreover, we introduce a generalization of earlier models that has a wider range of applicability, in terms of plasma injection profiles. We conclude by showing a straightforward way to extend the discussed solutions to the case of a plasma plume injected with non-null azimuthal velocity.

  1. Similarity Solutions of the Compressible Flow Equations for a General Equation of State

    NASA Astrophysics Data System (ADS)

    Boyd, Zachary; Ramsey, Scott; Baty, Roy

    2015-11-01

    The Euler compressible flow equations admit discontinuous (e.g. shock) solutions regardless of the equation of state (EOS) used to close them. In addition, certain classes of initial conditions and EOS admit special flows known as similarity solutions, including some containing shocks. These are useful (1) as test problems for hydrocodes, (2) as intermediate asymptotic estimates for non-symmetric problems, and (3) in forecasting experimental results. To date, the vast majority of work pertaining to similarity solutions of the Euler equations has been accomplished in the context of the ideal gas EOS; the case where the material is arbitrary is less well-understood. In this work, we classify using Lie-group analysis those materials which admit similarity solutions. We also indicate how such solutions may be found for a variety of materials of interest, including those characterized by particular forms of the Gruneisen EOS. Graduate Student Department of Mathematics, UCLA.

  2. f-state luminescence of lanthanide and actinide ions in solution

    SciTech Connect

    Beitz, J.V.

    1993-09-01

    Detailed studies of the luminescence of aquated Am{sup 3+} are presented in the context of prior lanthanide and actinide ion work. The luminescing state of aquated Am{sup 3+} is confirmed to be {sup 5}D{sub l} based on observed emission and excitation spectra. The luminescence lifetime of Am{sup 3+} in H{sub 2}O solution is (22 {plus_minus} 3) ns and (155 {plus_minus} 4) ns in D{sub 2}O solution at 295 K. Judd-Ofelt transition intensity theory qualitatively describes the observed Am{sup 3+} relative integrated fluorescence intensities. Recent luminescence studies on complexed trivalent f-element ions in solution are reviewed as to the similarities and differences between lanthanide ion 4f state and actinide ion 5f state properties.

  3. Model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory.

    PubMed

    Fletcher, Paul D I; Savory, Luke D; Woods, Freya; Clarke, Andrew; Howe, Andrew M

    2015-03-17

    With the aim of elucidating the details of enhanced oil recovery by surfactant solution flooding, we have determined the detailed behavior of model systems consisting of a packed column of calcium carbonate particles as the porous rock, n-decane as the trapped oil, and aqueous solutions of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The AOT concentration was varied from zero to above the critical aggregation concentration (cac). The salt content of the aqueous solutions was varied to give systems of widely different, post-cac oil-water interfacial tensions. The systems were characterized in detail by measuring the permeability behavior of the packed columns, the adsorption isotherms of AOT from the water to the oil-water interface and to the water-calcium carbonate interface, and oil-water-calcium carbonate contact angles. Measurements of the percent oil recovery by pumping surfactant solutions into calcium carbonate-packed columns initially filled with oil were analyzed in terms of the characterization results. We show that the measured contact angles as a function of AOT concentration are in reasonable agreement with those calculated from values of the surface energy of the calcium carbonate-air surface plus the measured adsorption isotherms. Surfactant adsorption onto the calcium carbonate-water interface causes depletion of its aqueous-phase concentration, and we derive equations which enable the concentration of nonadsorbed surfactant within the packed column to be estimated from measured parameters. The percent oil recovery as a function of the surfactant concentration is determined solely by the oil-water-calcium carbonate contact angle for nonadsorbed surfactant concentrations less than the cac. For surfactant concentrations greater than the cac, additional oil removal occurs by a combination of solubilization and emulsification plus oil mobilization due to the low oil-water interfacial tension and a pumping pressure increase. PMID

  4. Does State Aid Stimulate Public Library Expenditures? Evidence from Pennsylvania's Enhancement Aid Program

    ERIC Educational Resources Information Center

    Stine, William F.

    2006-01-01

    Pennsylvania public libraries began receiving increased allotments of state aid in 2000. In the first two years of enhancement aid, total state aid received by Pennsylvania libraries more than doubled. This reversed the trend of little growth in the years preceding 2000. The enhancement aid program also redesigned certain categories of state aid…

  5. Analytical steady-state solutions for water-limited cropping systems using saline irrigation water

    NASA Astrophysics Data System (ADS)

    Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.

    2014-12-01

    Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess advantages over available alternatives, including: (i) the solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.

  6. Spatial and temporal variation of surface-enhanced Raman scattering at Ag nanowires in aqueous solution

    SciTech Connect

    Clayton, Daniel A.; McPherson, Tyler; Pan, Shanlin; Chen, Mingyang; Dixon, David A.; Hu, Dehong

    2012-12-13

    We present surface enhanced Raman spectroscopy (SERS) and Raman imaging of small organic molecules at well-defined nanostructures formed by single silver nanowires (NWs). We show that SERS can be obtained at single, crossed, and bundled Ag NWs for mercaptopyridine, adenine, cytosine, guanine, and thymine. Crossed wires and parallel Ag NWs have SERS enhancement factors much higher than single Ag NWs. New additional junctions formed by a silver nanoparticle and a single Ag NW, and bundled NWs provide SERS intensity higher than a single Ag NW. The SERS signal of single Ag NWs can be further enhanced by decorating the Ag NW surface with gold nanoparticles using electroless deposition. Single Ag NW Raman imaging with a 10 ms time resolution when compared with photoluminescence (PL) imaging results reveal a different dynamic response of SERS and PL under steady state laser excitation. Dynamic photoluminescence blinking activities are suppressed in the presence of the surface coating of Raman active molecules (e.g., mercaptopyridine) and the SERS signal is quite stable in a wide field excitation configuration. The Discrete Dipole Approximation (DDA) method was used to calculate the local field intensity that can be applied to help understand the enhanced PL and SERS at the junction of Ag NWs

  7. Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li-O2 batteries

    NASA Astrophysics Data System (ADS)

    Aetukuri, Nagaphani B.; McCloskey, Bryan D.; García, Jeannette M.; Krupp, Leslie E.; Viswanathan, Venkatasubramanian; Luntz, Alan C.

    2015-01-01

    Given their high theoretical specific energy, lithium-oxygen batteries have received enormous attention as possible alternatives to current state-of-the-art rechargeable Li-ion batteries. However, the maximum discharge capacity in non-aqueous lithium-oxygen batteries is limited to a small fraction of its theoretical value due to the build-up of insulating lithium peroxide (Li2O2), the battery’s primary discharge product. The discharge capacity can be increased if Li2O2 forms as large toroidal particles rather than as a thin conformal layer. Here, we show that trace amounts of electrolyte additives, such as H2O, enhance the formation of Li2O2 toroids and result in significant improvements in capacity. Our experimental observations and a growth model show that the solvating properties of the additives prompt a solution-based mechanism that is responsible for the growth of Li2O2 toroids. We present a general formalism describing an additive’s tendency to trigger the solution process, providing a rational design route for electrolytes that afford larger lithium-oxygen battery capacities.

  8. Composite versus single transportable carbohydrate solution enhances race and laboratory cycling performance.

    PubMed

    Rowlands, David S; Swift, Marilla; Ros, Marjolein; Green, Jackson G

    2012-06-01

    When ingested at high rates (1.8-2.4 g·min(-1)) in concentrated solutions, carbohydrates absorbed by multiple (e.g., fructose and glucose) vs. single intestinal transporters can increase exogenous carbohydrate oxidation and endurance performance, but their effect when ingested at lower, more realistic, rates during intermittent high-intensity endurance competition and trials is unknown. Trained cyclists participated in two independent randomized crossover investigations comprising mountain-bike races (average 141 min; n = 10) and laboratory trials (94-min high-intensity intervals followed by 10 maximal sprints; n = 16). Solutions ingested during exercise contained electrolytes and fructose + maltodextrin or glucose + maltodextrin in 1:2 ratio ingested, on average, at 1.2 g carbohydrate·kg(-1)·h(-1). Exertion, muscle fatigue, and gastrointestinal discomfort were recorded. Data were analysed using mixed models with gastrointestinal discomfort as a mechanism covariate; inferences were made against substantiveness thresholds (1.2% for performance) and standardized difference. The fructose-maltodextrin solution substantially reduced race time (-1.8%; 90% confidence interval = ±1.8%) and abdominal cramps (-8.1 on a 0-100 scale; ±6.6). After accounting for gastrointestinal discomfort, the effect of the fructose-maltodextrin solution on lap time was reduced (-1.1%; ±2.4%), suggesting that gastrointestinal discomfort explained part of the effect of fructose-maltodextrin on performance. In the laboratory, mean sprint power was enhanced (1.4%; ±0.8%) with fructose-maltodextrin, but the effect on peak power was unclear (0.7%; ±1.5%). Adjusting out gastrointestinal discomfort augmented the fructose-maltodextrin effect on mean (2.6%; ±1.9%) and peak (2.5%; ±3.0%) power. Ingestion of multiple transportable vs. single transportable carbohydrates enhanced mountain-bike race and high-intensity laboratory cycling performance, with inconsistent but not irreconcilable effects

  9. Rapid assignment of solution 31P NMR spectra of large proteins by solid-state spectroscopy.

    PubMed

    Iuga, Adriana; Spoerner, Michael; Ader, Christian; Brunner, Eike; Kalbitzer, Hans Robert

    2006-07-21

    The application of the (31)P NMR spectroscopy to large proteins or protein complexes in solution is hampered by a relatively low intrinsic sensitivity coupled with large line widths. Therefore, the assignment of the phosphorus signals by two-dimensional NMR methods in solution is often extremely time consuming. In contrast, the quality of solid-state NMR spectra is not dependent on the molecular mass and the solubility of the protein. For the complex of Ras with the GTP-analogue GppCH(2)p we show solid-state (31)P NMR methods to be more sensitive by almost one order of magnitude than liquid-state NMR. Thus, solid-state NMR seems to be the method of choice for obtaining the resonance assignment of the phosphorus signals of protein complexes in solution. Experiments on Ras.GDP complexes show that the microcrystalline sample can be substituted by a precipitate of the sample and that unexpectedly the two structural states observed earlier in solution are present in crystals as well.

  10. On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid-State and Dissolution (13) C NMR Spectroscopy.

    PubMed

    Bretschneider, Christian O; Akbey, Ümit; Aussenac, Fabien; Olsen, Greg L; Feintuch, Akiva; Oschkinat, Hartmut; Frydman, Lucio

    2016-09-01

    Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid-state polarization enhancement at ambient conditions, and the maximization of (13) C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's (13) C behavior in nano- and micro-particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid-state experiments. It was found that (13) C NMR signals could be boosted by orders of magnitude in either low- or room-temperature solid-state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin-lattice relaxation times characteristic of diamond, coupled with a time-independent cross-effect-like polarization transfer mechanism facilitated by a matching of the nitrogen-related hyperfine coupling and the (13) C Zeeman splitting. The efficiency of this solid-state polarization process, however, is harder to exploit in dissolution DNP-enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed. PMID:27416769

  11. On The Potential of Dynamic Nuclear Polarization Enhanced Diamonds in Solid-State and Dissolution (13) C NMR Spectroscopy.

    PubMed

    Bretschneider, Christian O; Akbey, Ümit; Aussenac, Fabien; Olsen, Greg L; Feintuch, Akiva; Oschkinat, Hartmut; Frydman, Lucio

    2016-09-01

    Dynamic nuclear polarization (DNP) is a versatile option to improve the sensitivity of NMR and MRI. This versatility has elicited interest for overcoming potential limitations of these techniques, including the achievement of solid-state polarization enhancement at ambient conditions, and the maximization of (13) C signal lifetimes for performing in vivo MRI scans. This study explores whether diamond's (13) C behavior in nano- and micro-particles could be used to achieve these ends. The characteristics of diamond's DNP enhancement were analyzed for different magnetic fields, grain sizes, and sample environments ranging from cryogenic to ambient temperatures, in both solution and solid-state experiments. It was found that (13) C NMR signals could be boosted by orders of magnitude in either low- or room-temperature solid-state DNP experiments by utilizing naturally occurring paramagnetic P1 substitutional nitrogen defects. We attribute this behavior to the unusually long electronic/nuclear spin-lattice relaxation times characteristic of diamond, coupled with a time-independent cross-effect-like polarization transfer mechanism facilitated by a matching of the nitrogen-related hyperfine coupling and the (13) C Zeeman splitting. The efficiency of this solid-state polarization process, however, is harder to exploit in dissolution DNP-enhanced MRI contexts. The prospects for utilizing polarized diamond approaching nanoscale dimensions for both solid and solution applications are briefly discussed.

  12. Anomalously enhanced hydration of aqueous electrolyte solution in hydrophobic carbon nanotubes to maintain stability.

    PubMed

    Ohba, Tomonori

    2014-02-24

    An understanding of the structure and behavior of electrolyte solutions in nanoenvironements is crucial not only for a wide variety of applications, but also for the development of physical, chemical, and biological processes. We demonstrate the structure and stability of electrolyte in carbon nanotubes using hybrid reverse Monte Carlo simulations of X-ray diffraction patterns. Hydrogen bonds between water are adequately formed in carbon nanotubes, although some hydrogen bonds are restricted by the interfaces of carbon nanotubes. The hydrogen bonding network of water in electrolyte in the carbon nanotubes is further weakened. On the other hand, formation of the ion hydration shell is significantly enhanced in the electrolyte in the carbon nanotubes in comparison to ion hydration in bulk electrolyte. The significant hydrogen bond and hydration shell formation are a result of gaining stability in the hydrophobic nanoenvironment.

  13. Cavity enhanced detection methods for probing the dynamics of spin correlated radical pairs in solution

    NASA Astrophysics Data System (ADS)

    Neil, Simon R. T.; Maeda, Kiminori; Henbest, Kevin B.; Goez, Martin; Hemmens, Robert; Timmel, Christiane R.; Mackenzie, Stuart R.

    2010-04-01

    Cavity enhanced absorption spectroscopy (CEAS) combined with phase-sensitive detection is employed to study the effects of static magnetic fields on radical recombination reactions. The chemical system comprises the photochemically generated thionine semiquinone radical and a 1,4-diazabicyclo[2.2.2]octane (DABCO) cationic radical in a micellar solution of sodium dodecyl sulphate. Data obtained using the modulated CEAS technique, describing the magnetic field effect (MFE) on reaction yields, are shown to be superior to those obtained using conventional transient absorption (TA) flash photolysis methods typically employed for these measurements. The high sensitivity afforded by modulated CEAS detection is discussed in terms of the new possibilities it offers such as the measurement of magnetic field effects in real biological systems which have hitherto been largely beyond the detection capabilities of existing techniques.

  14. Dependence of fluorescent protein brightness on protein concentration in solution and enhancement of it

    PubMed Central

    Morikawa, Takamitsu J.; Fujita, Hideaki; Kitamura, Akira; Horio, Takashi; Yamamoto, Johtaro; Kinjo, Masataka; Sasaki, Akira; Machiyama, Hiroaki; Yoshizawa, Keiko; Ichimura, Taro; Imada, Katsumi; Nagai, Takeharu; Watanabe, Tomonobu M.

    2016-01-01

    Fluorescent proteins have been widely used in biology because of their compatibility and varied applications in living specimens. Fluorescent proteins are often undesirably sensitive to intracellular conditions such as pH and ion concentration, generating considerable issues at times. However, harnessing these intrinsic sensitivities can help develop functional probes. In this study, we found that the fluorescence of yellow fluorescent protein (YFP) depends on the protein concentration in the solution and that this dependence can be enhanced by adding a glycine residue in to the YFP; we applied this finding to construct an intracellular protein-crowding sensor. A Förster resonance energy transfer (FRET) pair, involving a cyan fluorescent protein (CFP) insensitive to protein concentration and a glycine-inserted YFP, works as a genetically encoded probe to evaluate intracellular crowding. By measuring the fluorescence of the present FRET probe, we were able to detect dynamic changes in protein crowding in living cells. PMID:26956628

  15. Enhanced ozonation of dichloroacetic acid in aqueous solution using nanometer ZnO powders.

    PubMed

    Zhai, Xu; Chen, Zhonglin; Zhao, Shuqing; Wang, He; Yang, Lei

    2010-01-01

    Nanometer zinc oxide (ZnO) powders were used as a catalyst to enhance the ozonation for the degradation of dichloroacetic acid (DCAA) in aqueous solution. The batch experiments were carried out to investigate the effects of key factors such as catalyst dosage, ozone dosage, solution pH and tert-butyl alcohol (t-BuOH) on the degradation efficiency of DCAA. Density functional theory (DFT) was adopted to explore the mechanism of generating hydroxyl radical (*OH) on the ZnO surface. The results showed that adsorption and ozonation processes were not effective for DCAA removal, and the addition of ZnO catalyst improved the degradation efficiency of DCAA during ozonation, which caused an increase of 22.8% for DCAA decomposition compared to the case of ozonation alone after 25 min. Under the same experimental conditions, the DCAA decomposition was enhanced by increasing catalyst dosage from 100 to 500 mg/L and ozone dosage from 0.83 to 3.2 mg/L. The catalytic ozonation process is more pronounced than the ozonation process alone at pH 3.93, 6.88, and 10. With increasing the concentration of t-BuOH from 10 to 200 mg/L, the degradation of DCAA was significantly inhibited in the process of catalytic ozonation, indicating that ZnO catalytic ozonation followed *OH reaction mechanism. Based on the experimental results and DFT analysis, it is deduced that the generation of *OH on the ZnO surface is ascribed to the adsorption of molecule ozone followed by the interaction of adsorbed ozone with active sites of the catalyst surface. It is also concluded that ZnO may be an effective catalyst for DCAA removal, which could promote the formation of *OH derived from the catalytic decomposition of ozone. PMID:21235181

  16. Microbially-Enhanced Redox Solution Reoxidation for Sour Natural Gas Sweetening

    SciTech Connect

    Kenneth Brezinsky

    2008-01-15

    The specific objective of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes such as LO-CAT II and SulFerox process utilizing biologically enhanced reoxidation of the redox solutions used in these processes. The project is based on the use of chelated ferric iron as the catalyst for the production of elemental sulfur, and then oxidizing bacteria, such as Thiobacillus Ferrooxidans (ATCC 23270) as an oxidizer. The regeneration of Fe{sup 3+} - chelate is accomplished by the use of these same microbes under mild conditions at 25-30 C and at atmospheric pressure to minimize the chelate degradation process. The pH of the redox solution was observed to be a key process parameter. Other parameters such as temperature, total iron concentration, gas to liquid ratio and bacterial cell densities also influence the overall process. The second part of this project includes experimental data and a kinetic model of microbial H{sub 2}S removal from sour natural gas using thiobacillus species. In the experimental part, a series of experiments were conducted with a commercial chelated iron catalyst at pH ranges from 8.7 to 9.2 using a total iron concentration range from 925 ppm to 1050 ppm in the solution. Regeneration of the solution was carried out by passing air through the solution. Iron oxidizing bacteria were used at cell densities of 2.3 x 10{sup 7}cells/ml for optimum effective performance. In the modeling part, oxidation of Fe{sup 2+} ions by the iron oxidizing bacteria - Thiobacillus Ferrooxidans was studied for application to a continuous stirred tank reactor (CSTR). The factors that can directly affect the oxidation rate such as dilution rate, temperature, and pH were analyzed. The growth of the microorganism was assumed to follow Monod type of growth kinetics. Dilution rate had influence on the rate of oxidation of ferrous iron. Higher dilution rates caused washout of the biomass. The oxidation rate was

  17. Enhanced copper surface protection in aqueous solutions containing short-chain alkanoic acid potassium salts.

    PubMed

    Abelev, Esta; Starosvetsky, David; Ein-Eli, Yair

    2007-10-23

    The ability of dissolved potassium monocarboxylate salts to produce surface passivation and to inhibit aqueous corrosion of copper was studied. The electrochemical measurements indicate that the inhibiting efficiency of these compounds, with a general formula Cn-1H2n-1COOK or CnK (n=3...12), is dependent on the hydrocarbon chain length. The inhibiting efficiency was higher for a longer hydrocarbon chain of n-alkanoic acid. The degree of copper protection was found to increase with an increase in n-alkanoic acid potassium salt concentration; the optimum concentration of potassium dodecanoate (C12K) in sulfate solutions was found to be 0.07 M. The protective layers formed at the copper surface subsequent to exposure in various n-alkanoic acid potassium salt solutions were characterized by contact angle measurements, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared reflection spectroscopy. Pronounced copper protection was attributed to the growth of a protective film on the copper surface, containing both copper oxides and copper carboxylate compounds. It is suggested that the organic molecules enhance copper protection by covering copper oxides with a thin and dense organic layer, which prevents water molecules or aggressive anions from interacting with the copper surface.

  18. State-space solutions to standard H2 and H(infinity) control problems

    NASA Technical Reports Server (NTRS)

    Doyle, John C.; Glover, Keith; Khargonekar, Pramod P.; Francis, Bruce A.

    1989-01-01

    Simple state-space formulas are derived for all controllers solving the standard H(infinity) problem of finding, for a given number gamma greater than 0, all controllers such that the H(infinity) norm of the closed-loop transfer function is (strictly) less than gamma. It is known that a controller exists if and only if the unique stabilizing solutions to two algebraic Riccati equations are positive definite and the spectral radius of their product is less than gamma squared. Under these conditions, a parameterization of all controllers solving the problem is given as a linear fractional transformation (LFT) on a contractive stable free parameter. The state dimension of the coefficient matrix for the LFT, constructed using the two Riccati solutions, equals that of the plant and has a separation structure reminiscent of classical LQG (i.e., H2) theory. A standard H2 solution is developed in parallel.

  19. αB-Crystallin. A Hybrid Solid-State/Solution-State NMR Investigation Reveals Structural Aspects of the Heterogeneous Oligomer

    SciTech Connect

    Jehle, Stefan; van Rossum, Barth; Stout, Joseph R.; Noguchi, Satoshi M.; Falber, Katja; Rehbein, Kristina; Oschkinat, Hartmut; Klevit, Rachel E.; Rajagopal, Ponni

    2008-11-14

    Atomic-level structural information on αB-Crystallin (αB), a prominent member of the small heat-shock protein family, has been a challenge to obtain due its polydisperse oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on an ~580-kDa human αB assembled from 175-residue 20-kDa subunits. An ~100-residue α-crystallin domain is common to all small heat-shock proteins, and solution-state NMR was performed on two different α- crystallin domain constructs isolated from αB. In vitro, the chaperone-like activities of full-length αB and the isolated α-crystallin domain are identical. Chemical shifts of the backbone and Cβ resonances have been obtained for residues 64–162 (α-crystallin domain plus part of the C-terminus) in αB and the isolated α-crystallin domain by solid-state and solution-state NMR, respectively. Both sets of data strongly predict six β-strands in the α-crystallin domain. A majority of residues in the α-crystallin domain have similar chemical shifts in both solid-state and solution-state, indicating similar structures for the domain in its isolated and oligomeric forms. Sites of intersubunit interaction are identified from chemical shift differences that cluster to specific regions of the α-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within αB. Evidence for a novel dimerization motif in the human α-crystallin domain is obtained by a comparison of (i) solid-state and solution-state chemical shift data and (ii) 1H–15N heteronuclear single quantum coherence spectra as a function of pH. The isolated α-crystallin domain undergoes a dimer–monomer transition over the pH range 7.5–6.8. This steep pHdependent switch may be important for αB to function optimally (e.g., to preserve the filament integrity

  20. The equation of state for solutions of the sunflower oil+isomerhexane system

    NASA Astrophysics Data System (ADS)

    Safarov, M. M.; Abdukhamidova, Z.

    1995-11-01

    The article presents the results of an experimental investigation into the density of solutions of the sunflower oil+isomerhexane system (from 23 to 75%) at temperatures of from 293 to 450 K and pressures of from 0.101 to 98.1 MPa. An equation of state is obtained.

  1. USING HIGH-RESOLUTION SOLUTION-STATE NMR SPECTROSCOPY TO INVESTIGATE PMDI REACTIONS WITH WOOD

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solution-state NMR spectroscopy provides a powerful tool for understanding the formation of chemical bonds between wood components and adhesives. Finely ground cell wall (CW) material fully dissolves in a solvent system containing dimethylsulfoxide (DMSO-d6) and N-methyl¬imidazole (NMI-d6), keeping ...

  2. Bound and Scattering State Solutions of Schrodinger Equation for Asymmetric Woods Saxon Potential

    NASA Astrophysics Data System (ADS)

    Candemir, N.

    2012-06-01

    The one-dimensional time-independent Schrödinger equation is solved for asymmetric Woods-Saxon potential. The reflection and transmission coefficients and bound state solutions are obtained in terms of hypergeometric functions. Some useful figures are plotted to show the accuracy of the obtained results.

  3. Convergence to steady state solutions of the Euler equations on unstructured grids with limiters

    SciTech Connect

    Venkatakrishnan, V.

    1995-04-01

    This paper addresses the practical problem of obtaining convergence to steady state solutions of the Euler equations when limiters are used in conjunction with upwind schemes on unstructured grids. The base scheme forms a gradient and limits it by imposing monotonicity conditions in the reconstruction stage. It is shown by analysis in one dimension that such an approach leads to various schemes meeting total-variation-diminishing requirements in one dimension. In multiple dirnensions these schemes produce steadystate solutions that are monotone and devoid of oscillations. However, convergence stalls after a few orders of reduction in the residual. A new limiter is introduced that is particularly suited for unstructured grid applications. When reduced to one dimension, it is shown that this limiter satisfies the standard theory. With this limiter, it is shown that converged steady-state solutions can be obtained. However, the solutions are not monotone. There appears to be a conflict between achieving convergence and monotone solutions with the higher order schemes that employ limiters in the framework presented.

  4. Combining solid-state and solution-state 31P NMR to study in vivo phosphorus metabolism.

    PubMed Central

    Cholli, A L; Yamane, T; Jelinski, L W

    1985-01-01

    Otherwise unavailable information concerning the distribution of phosphorylated compounds in biological systems is obtained by a combined solid-state/solution-state NMR approach, illustrated here for oocytes from Rana pipiens. General methodology is developed, and further extensions are proposed. The following conclusions pertain to the specific system under examination. (i) Nucleoside phosphates can be observed by magic-angle sample spinning of the lyophilized material. (ii) The solid-state NMR technique of dipolar decoupling provides no additional resolution of the phospholipid and phosphoprotein components of the yolk. However, cellular death produces sufficient pH changes to cause the phospholipid and protein phosphate peaks to become resolvable. The concentration of nucleoside phosphates also decreases. (iii) The phospholipid and phosphoprotein components are shown by computer simulation to be present in a ratio of 40:60, respectively. (iv) The amounts of inorganic phosphate, nucleoside phosphates, and sugar phosphates are determined by solution-state NMR observation of the perchloric acid extract of the oocytes. PMID:3871524

  5. The potential for solubilizing agents to enhance the remediation of hydrophobic organic solutes in soil-water suspensions. [Quarterly report

    SciTech Connect

    Laha, S.; Liu, Z.; Edwards, D.; Luthy, R.G.

    1991-02-01

    This paper discusses the feasibility for use of surfactant solubilizing agents to enhance the solubility and the rate of microbial degradation of hydrophobic organic solutes in soil-water suspensions. Hydrophobic organic contaminants are strongly sorbed to soil or sediment material, and as a consequence the rate of microbial degradation may depend greatly on the desorption of the sorbed-phase contaminant and the accessibility of the contaminant to soil microorganisms. Chemical solubilizing agents may enhance the rate of hydrophobic organic solute degradation by increasing the rate of solute desorption from soil and the extent of solute partitioning to the aqueous phase. The presentation will review on-going research on: surfactant solubilization of polycyclic aromatic hydrocarbon (PAH) compounds in clean water, and in soil-water suspensions; and experiments to assess if the addition of surfactant to soil-water suspension results in faster rate of mineralization of PAH compounds in soil.

  6. The potential for solubilizing agents to enhance the remediation of hydrophobic organic solutes in soil-water suspensions

    SciTech Connect

    Laha, S.; Liu, Z.; Edwards, D.; Luthy, R.G.

    1991-02-01

    This paper discusses the feasibility for use of surfactant solubilizing agents to enhance the solubility and the rate of microbial degradation of hydrophobic organic solutes in soil-water suspensions. Hydrophobic organic contaminants are strongly sorbed to soil or sediment material, and as a consequence the rate of microbial degradation may depend greatly on the desorption of the sorbed-phase contaminant and the accessibility of the contaminant to soil microorganisms. Chemical solubilizing agents may enhance the rate of hydrophobic organic solute degradation by increasing the rate of solute desorption from soil and the extent of solute partitioning to the aqueous phase. The presentation will review on-going research on: surfactant solubilization of polycyclic aromatic hydrocarbon (PAH) compounds in clean water, and in soil-water suspensions; and experiments to assess if the addition of surfactant to soil-water suspension results in faster rate of mineralization of PAH compounds in soil.

  7. Numerical solution of a coupled pair of elliptic equations from solid state electronics

    NASA Technical Reports Server (NTRS)

    Phillips, T. N.

    1984-01-01

    Iterative methods are considered for the solution of a coupled pair of second order elliptic partial differential equations which arise in the field of solid state electronics. A finite difference scheme is used which retains the conservative form of the differential equations. Numerical solutions are obtained in two ways, by multigrid and dynamic alternating direction implicit methods. Numerical results are presented which show the multigrid method to be an efficient way of solving this problem. Previously announced in STAR as N83-30109

  8. A multi-level solution algorithm for steady-state Markov chains

    NASA Technical Reports Server (NTRS)

    Horton, Graham; Leutenegger, Scott T.

    1993-01-01

    A new iterative algorithm, the multi-level algorithm, for the numerical solution of steady state Markov chains is presented. The method utilizes a set of recursively coarsened representations of the original system to achieve accelerated convergence. It is motivated by multigrid methods, which are widely used for fast solution of partial differential equations. Initial results of numerical experiments are reported, showing significant reductions in computation time, often an order of magnitude or more, relative to the Gauss-Seidel and optimal SOR algorithms for a variety of test problems. The multi-level method is compared and contrasted with the iterative aggregation-disaggregation algorithm of Takahashi.

  9. State Financial Aid: Policies to Enhance Articulation and Transfer

    ERIC Educational Resources Information Center

    Long, Bridget Terry

    2005-01-01

    Financing and financial aid issues in higher education continue to plague state policymakers and higher education leaders. Every year, they struggle with questions of how to meet growing needs through state allocations, how best to ensure shared and equitable responsibility for paying for higher education, and how best to use subsidies such as…

  10. A hybrid multigrid technique for computing steady-state solutions to supersonic flows

    NASA Technical Reports Server (NTRS)

    Sanders, Richard

    1992-01-01

    Recently, Li and Sanders have introduced a class of finite difference schemes to approximate generally discontinuous solutions to hyperbolic systems of conservation laws. These equations have the form together with relevant boundary conditions. When modelling hypersonic spacecraft reentry, the differential equations above are frequently given by the compressible Euler equations coupled with a nonequilibrium chemistry model. For these applications, steady state solutions are often sought. Many tens (to hundreds) of super computer hours can be devoted to a single three space dimensional simulation. The primary difficulty is the inability to rapidly and reliably capture the steady state. In these notes, we demonstrate that a particular variant from the schemes presented can be combined with a particular multigrid approach to capture steady state solutions to the compressible Euler equations in one space dimension. We show that the rate of convergence to steady state coming from this multigrid implementation is vastly superior to the traditional approach of artificial time relaxation. Moreover, we demonstrate virtual grid independence. That is, the rate of convergence does not depend on the degree of spatial grid refinement.

  11. Nanofibers of Elastin and Hydrophilic Segmented Polyurethane Solution Blends Show Enhanced Mechanical Properties through Intermolecular Protein-Polymer H Bonding.

    PubMed

    Heiny, Markus; Shastri, V Prasad

    2016-04-11

    Combining mechanical properties with enhanced cell interaction is highly desirable in a biomaterial. In this study, a new paradigm for enhancing the mechanical properties of segmented polyurethanes (SPUs) through solution blending with a biopolymer is presented. This noncovalent approach is based on the premise that molecular level blending of SPUs rich in hydrogen bonding (H bonding) domains with a biopolymer capable of H bonding will promote H-bond bridges between the components, leading to molecular annealing and modification of the physicochemical properties of the SPU. We demonstrate that by solution-blending solubilized elastin with a triblock copolymer-derived SPU, a 5-fold increase in tensile modulus of electrospun constructs of the SPU can be achieved, with concomitant enhancement in human endothelial cell attachment. Spectroscopic and calorimetric analysis confirm the role of H bonding in the enhancement, thus providing the impetus to further explore blending with biopolymers as a means of improving the property profiles of synthetic polymeric biomaterials. PMID:26940665

  12. Nanofibers of Elastin and Hydrophilic Segmented Polyurethane Solution Blends Show Enhanced Mechanical Properties through Intermolecular Protein-Polymer H Bonding.

    PubMed

    Heiny, Markus; Shastri, V Prasad

    2016-04-11

    Combining mechanical properties with enhanced cell interaction is highly desirable in a biomaterial. In this study, a new paradigm for enhancing the mechanical properties of segmented polyurethanes (SPUs) through solution blending with a biopolymer is presented. This noncovalent approach is based on the premise that molecular level blending of SPUs rich in hydrogen bonding (H bonding) domains with a biopolymer capable of H bonding will promote H-bond bridges between the components, leading to molecular annealing and modification of the physicochemical properties of the SPU. We demonstrate that by solution-blending solubilized elastin with a triblock copolymer-derived SPU, a 5-fold increase in tensile modulus of electrospun constructs of the SPU can be achieved, with concomitant enhancement in human endothelial cell attachment. Spectroscopic and calorimetric analysis confirm the role of H bonding in the enhancement, thus providing the impetus to further explore blending with biopolymers as a means of improving the property profiles of synthetic polymeric biomaterials.

  13. Enhanced control of saddle steady states of dynamical systems.

    PubMed

    Tamaševičius, Arūnas; Tamaševičiūtė, Elena; Mykolaitis, Gytis; Bumelienė, Skaidra

    2013-09-01

    An adaptive feedback technique for stabilizing a priori unknown saddle steady states of dynamical systems is described. The method is based on an unstable low-pass filter combined with a stable low-pass filter. The cutoff frequencies of both filters can be set relatively high. This allows considerable increase in the rate of convergence to the steady state. We demonstrate numerically and experimentally that the technique is robust to the influence of unknown external forces, which change the position of the steady state in the phase space. Experiments have been performed using electrical circuits imitating the damped Duffing-Holmes and chaotic Lindberg systems. PMID:24125322

  14. Steady-state thermal-solutal convection and diffusion in a simulated float zone

    NASA Technical Reports Server (NTRS)

    Young, G. W.; Chait, A.

    1990-01-01

    Models describing the steady-state thermal diffusion in a pure system, the thermal-solutal diffusion in a binary system, and heat and momentum transverse in a pure system are presented. The geometry of the model is described by a 2D Cartesian coordinate system that is applicable for crystal sheets. The melting, solidifying, and melt/gas interfacial shapes as well as the thermal, flow, and solutal profiles are analytically evaluated as functions of the heat and ambient temperature profiles and material properties. The solution procedure involves a coupled asymptotic/numerical approach which reduces the coupled set of partial differential equations to ordinary type. The results should be applicable in situations where melt flows are not intense enough to change the thermal field in pure systems, or where the physical properties of the melt are such that the convective field is decoupled from the thermal field, the latter being established primarily by diffusion.

  15. State space truncation with quantified errors for accurate solutions to discrete Chemical Master Equation

    PubMed Central

    Cao, Youfang; Terebus, Anna; Liang, Jie

    2016-01-01

    The discrete chemical master equation (dCME) provides a general framework for studying stochasticity in mesoscopic reaction networks. Since its direct solution rapidly becomes intractable due to the increasing size of the state space, truncation of the state space is necessary for solving most dCMEs. It is therefore important to assess the consequences of state space truncations so errors can be quantified and minimized. Here we describe a novel method for state space truncation. By partitioning a reaction network into multiple molecular equivalence groups (MEG), we truncate the state space by limiting the total molecular copy numbers in each MEG. We further describe a theoretical framework for analysis of the truncation error in the steady state probability landscape using reflecting boundaries. By aggregating the state space based on the usage of a MEG and constructing an aggregated Markov process, we show that the truncation error of a MEG can be asymptotically bounded by the probability of states on the reflecting boundary of the MEG. Furthermore, truncating states of an arbitrary MEG will not undermine the estimated error of truncating any other MEGs. We then provide an overall error estimate for networks with multiple MEGs. To rapidly determine the appropriate size of an arbitrary MEG, we also introduce an a priori method to estimate the upper bound of its truncation error. This a priori estimate can be rapidly computed from reaction rates of the network, without the need of costly trial solutions of the dCME. As examples, we show results of applying our methods to the four stochastic networks of 1) the birth and death model, 2) the single gene expression model, 3) the genetic toggle switch model, and 4) the phage lambda bistable epigenetic switch model. We demonstrate how truncation errors and steady state probability landscapes can be computed using different sizes of the MEG(s) and how the results validate out theories. Overall, the novel state space

  16. State Space Truncation with Quantified Errors for Accurate Solutions to Discrete Chemical Master Equation.

    PubMed

    Cao, Youfang; Terebus, Anna; Liang, Jie

    2016-04-01

    The discrete chemical master equation (dCME) provides a general framework for studying stochasticity in mesoscopic reaction networks. Since its direct solution rapidly becomes intractable due to the increasing size of the state space, truncation of the state space is necessary for solving most dCMEs. It is therefore important to assess the consequences of state space truncations so errors can be quantified and minimized. Here we describe a novel method for state space truncation. By partitioning a reaction network into multiple molecular equivalence groups (MEGs), we truncate the state space by limiting the total molecular copy numbers in each MEG. We further describe a theoretical framework for analysis of the truncation error in the steady-state probability landscape using reflecting boundaries. By aggregating the state space based on the usage of a MEG and constructing an aggregated Markov process, we show that the truncation error of a MEG can be asymptotically bounded by the probability of states on the reflecting boundary of the MEG. Furthermore, truncating states of an arbitrary MEG will not undermine the estimated error of truncating any other MEGs. We then provide an overall error estimate for networks with multiple MEGs. To rapidly determine the appropriate size of an arbitrary MEG, we also introduce an a priori method to estimate the upper bound of its truncation error. This a priori estimate can be rapidly computed from reaction rates of the network, without the need of costly trial solutions of the dCME. As examples, we show results of applying our methods to the four stochastic networks of (1) the birth and death model, (2) the single gene expression model, (3) the genetic toggle switch model, and (4) the phage lambda bistable epigenetic switch model. We demonstrate how truncation errors and steady-state probability landscapes can be computed using different sizes of the MEG(s) and how the results validate our theories. Overall, the novel state space

  17. Longitudinal-relaxation-enhanced NMR experiments for the study of nucleic acids in solution.

    PubMed

    Farjon, Jonathan; Boisbouvier, Jérôme; Schanda, Paul; Pardi, Arthur; Simorre, Jean-Pierre; Brutscher, Bernhard

    2009-06-24

    Atomic-resolution information on the structure and dynamics of nucleic acids is essential for a better understanding of the mechanistic basis of many cellular processes. NMR spectroscopy is a powerful method for studying the structure and dynamics of nucleic acids; however, solution NMR studies are currently limited to relatively small nucleic acids at high concentrations. Thus, technological and methodological improvements that increase the experimental sensitivity and spectral resolution of NMR spectroscopy are required for studies of larger nucleic acids or protein-nucleic acid complexes. Here we introduce a series of imino-proton-detected NMR experiments that yield an over 2-fold increase in sensitivity compared to conventional pulse schemes. These methods can be applied to the detection of base pair interactions, RNA-ligand titration experiments, measurement of residual dipolar (15)N-(1)H couplings, and direct measurements of conformational transitions. These NMR experiments employ longitudinal spin relaxation enhancement techniques that have proven useful in protein NMR spectroscopy. The performance of these new experiments is demonstrated for a 10 kDa TAR-TAR*(GA) RNA kissing complex and a 26 kDa tRNA.

  18. Iridium-Tin oxide solid-solution nanocatalysts with enhanced activity and stability for oxygen evolution

    NASA Astrophysics Data System (ADS)

    Li, Guangfu; Yu, Hongmei; Yang, Donglei; Chi, Jun; Wang, Xunying; Sun, Shucheng; Shao, Zhigang; Yi, Baolian

    2016-09-01

    Addressing major challenges from the material cost, efficiency and stability, it is highly desirable to develop high-performance catalysts for oxygen evolution reaction (OER). Herein we explore a facile surfactant-assisted approach for fabricating Irsbnd Sn (Ir/Sn = 0.6/0.4, by mol.) nano-oxide catalysts with good morphology control. Direct proofs from XRD and X-ray photoelectron spectra indicate hydrophilic triblock polymer (TBP, like Pluronic® F108) surfactant can boost the formation of stable solid-solution structure. With the TBP hydrophilic and block-length increase, the fabricated Irsbnd Sn oxides undergoing the rod-to-sphere transition obtain the relatively lower crystallization, decreased crystallite size, Ir-enriched surface and incremental available active sites, all of which can bolster the OER activity and stability. Meanwhile, it is observed that the coupled Ir oxidative etching takes a crucial role in determining the material structure and performance. Compared with commercial Ir black, half-cell tests confirm F108-assistant catalysts with over 40 wt% Ir loading reduction show 2-fold activity enhancement as well as significant stability improvement. The lowest cell voltage using 0.88 mg cm-2 Ir loading is only 1.621 V at 1000 mA cm-2 and 80 °C with a concomitant energy efficiency of 75.8% which is beyond the DOE 2017 efficiency target of 74%.

  19. Contribution of various components to the enhanced accuracy of GIPSY/OASIS II PPP solutions

    NASA Astrophysics Data System (ADS)

    Hayal, Adem G.; Ugur Sanli, D.

    2016-04-01

    The accuracy of GIPSY PPP has now been revised following the substantial improvements in JPL analysis strategies and product quality after the year 2007. The accuracy improvement in GIPSY solutions was due mainly to the rigorous analysis procedures adopted in computing the satellite orbits in JPL, incorporating single receiver ambiguity resolution among GIPSY modules, and applying a new 2nd order ionosphere modeling. The 2010 positioning accuracy model, which accounts for the procedures prior to 2007 enhancements, was refined in 2015 using a global set of International GNSS Service (IGS) stations and v. 6.3 of GIPSY/OASIS II software. This was just after the reprocessing of JPL final orbit products with second order ionospheric corrections (Oct/Nov 2014).The improvement in regard to precise satellite orbits was previously shared with research community by the NASA. However, comparative contribution of single receiver ambiguity resolution and 2nd order ionosphere correction into the accuracy model has not been assessed yet. Here we perform the so-called assessment and find that contribution of single receiver ambiguity resolution is comparatively greater than that of the 2nd order ionosphere modeling for our particular global sampling.

  20. Polymorphs of Theophylline Characterized by DNP Enhanced Solid-State NMR

    PubMed Central

    2015-01-01

    We show how dynamic nuclear polarization (DNP) enhanced solid-state NMR spectroscopy can be used to characterize polymorphs and solvates of organic solids. We applied DNP to three polymorphs and one hydrated form of the asthma drug molecule theophylline. For some forms of theophylline, sample grinding and impregnation with the radical-containing solution, which are necessary to prepare the samples for DNP, were found to induce polymorphic transitions or desolvation between some forms. We present protocols for sample preparation for solid-state magic-angle spinning (MAS) DNP experiments that avoid the polymorphic phase transitions in theophylline. These protocols include cryogrinding, grinding under inert atmosphere, and the appropriate choice of the impregnating liquid. By applying these procedures, we subsequently demonstrate that two-dimensional correlation experiments, such as 1H–13C and 1H–15N HETCOR or 13C–13C INADEQUATE, can be obtained at natural isotopic abundance in reasonable times, thus enabling more advanced structural characterization of polymorphs. PMID:26393368

  1. Polymorphs of Theophylline Characterized by DNP Enhanced Solid-State NMR.

    PubMed

    Pinon, Arthur C; Rossini, Aaron J; Widdifield, Cory M; Gajan, David; Emsley, Lyndon

    2015-11-01

    We show how dynamic nuclear polarization (DNP) enhanced solid-state NMR spectroscopy can be used to characterize polymorphs and solvates of organic solids. We applied DNP to three polymorphs and one hydrated form of the asthma drug molecule theophylline. For some forms of theophylline, sample grinding and impregnation with the radical-containing solution, which are necessary to prepare the samples for DNP, were found to induce polymorphic transitions or desolvation between some forms. We present protocols for sample preparation for solid-state magic-angle spinning (MAS) DNP experiments that avoid the polymorphic phase transitions in theophylline. These protocols include cryogrinding, grinding under inert atmosphere, and the appropriate choice of the impregnating liquid. By applying these procedures, we subsequently demonstrate that two-dimensional correlation experiments, such as (1)H-(13)C and (1)H-(15)N HETCOR or (13)C-(13)C INADEQUATE, can be obtained at natural isotopic abundance in reasonable times, thus enabling more advanced structural characterization of polymorphs.

  2. Stochastic quasi-steady state approximations for asymptotic solutions of the chemical master equation.

    PubMed

    Alarcón, Tomás

    2014-05-14

    In this paper, we propose two methods to carry out the quasi-steady state approximation in stochastic models of enzyme catalytic regulation, based on WKB asymptotics of the chemical master equation or of the corresponding partial differential equation for the generating function. The first of the methods we propose involves the development of multiscale generalisation of a WKB approximation of the solution of the master equation, where the separation of time scales is made explicit which allows us to apply the quasi-steady state approximation in a straightforward manner. To the lowest order, the multi-scale WKB method provides a quasi-steady state, Gaussian approximation of the probability distribution. The second method is based on the Hamilton-Jacobi representation of the stochastic process where, as predicted by large deviation theory, the solution of the partial differential equation for the corresponding characteristic function is given in terms of an effective action functional. The optimal transition paths between two states are then given by those paths that maximise the effective action. Such paths are the solutions of the Hamilton equations for the Hamiltonian associated to the effective action functional. The quasi-steady state approximation is applied to the Hamilton equations thus providing an approximation to the optimal transition paths and the transition time between two states. Using this approximation we predict that, unlike the mean-field quasi-steady approximation result, the rate of enzyme catalysis depends explicitly on the initial number of enzyme molecules. The accuracy and validity of our approximated results as well as that of our predictions regarding the behaviour of the stochastic enzyme catalytic models are verified by direct simulation of the stochastic model using Gillespie stochastic simulation algorithm.

  3. Stochastic quasi-steady state approximations for asymptotic solutions of the chemical master equation.

    PubMed

    Alarcón, Tomás

    2014-05-14

    In this paper, we propose two methods to carry out the quasi-steady state approximation in stochastic models of enzyme catalytic regulation, based on WKB asymptotics of the chemical master equation or of the corresponding partial differential equation for the generating function. The first of the methods we propose involves the development of multiscale generalisation of a WKB approximation of the solution of the master equation, where the separation of time scales is made explicit which allows us to apply the quasi-steady state approximation in a straightforward manner. To the lowest order, the multi-scale WKB method provides a quasi-steady state, Gaussian approximation of the probability distribution. The second method is based on the Hamilton-Jacobi representation of the stochastic process where, as predicted by large deviation theory, the solution of the partial differential equation for the corresponding characteristic function is given in terms of an effective action functional. The optimal transition paths between two states are then given by those paths that maximise the effective action. Such paths are the solutions of the Hamilton equations for the Hamiltonian associated to the effective action functional. The quasi-steady state approximation is applied to the Hamilton equations thus providing an approximation to the optimal transition paths and the transition time between two states. Using this approximation we predict that, unlike the mean-field quasi-steady approximation result, the rate of enzyme catalysis depends explicitly on the initial number of enzyme molecules. The accuracy and validity of our approximated results as well as that of our predictions regarding the behaviour of the stochastic enzyme catalytic models are verified by direct simulation of the stochastic model using Gillespie stochastic simulation algorithm. PMID:24832255

  4. Stochastic quasi-steady state approximations for asymptotic solutions of the chemical master equation

    SciTech Connect

    Alarcón, Tomás

    2014-05-14

    In this paper, we propose two methods to carry out the quasi-steady state approximation in stochastic models of enzyme catalytic regulation, based on WKB asymptotics of the chemical master equation or of the corresponding partial differential equation for the generating function. The first of the methods we propose involves the development of multiscale generalisation of a WKB approximation of the solution of the master equation, where the separation of time scales is made explicit which allows us to apply the quasi-steady state approximation in a straightforward manner. To the lowest order, the multi-scale WKB method provides a quasi-steady state, Gaussian approximation of the probability distribution. The second method is based on the Hamilton-Jacobi representation of the stochastic process where, as predicted by large deviation theory, the solution of the partial differential equation for the corresponding characteristic function is given in terms of an effective action functional. The optimal transition paths between two states are then given by those paths that maximise the effective action. Such paths are the solutions of the Hamilton equations for the Hamiltonian associated to the effective action functional. The quasi-steady state approximation is applied to the Hamilton equations thus providing an approximation to the optimal transition paths and the transition time between two states. Using this approximation we predict that, unlike the mean-field quasi-steady approximation result, the rate of enzyme catalysis depends explicitly on the initial number of enzyme molecules. The accuracy and validity of our approximated results as well as that of our predictions regarding the behaviour of the stochastic enzyme catalytic models are verified by direct simulation of the stochastic model using Gillespie stochastic simulation algorithm.

  5. An approximate solution to the stress and deformation states of functionally graded rotating disks

    NASA Astrophysics Data System (ADS)

    Sondhi, Lakshman; Sanyal, Shubhashis; Saha, Kashi Nath; Bhowmick, Shubhankar

    2016-07-01

    The present work employs variational principle to investigate the stress and deformation states and estimate the limit angular speed of functionally graded high-speed rotating annular disks of constant thickness. Assuming a series approximation following Galerkin's principle, the solution of the governing equation is obtained. In the present study, elasticity modulus and density of the disk material are taken as power function of radius with the gradient parameter ranging between 0.0 and 1.0. Results obtained from numerical solutions are validated with benchmark results and are found to be in good agreement. The results are reported in dimensional form and presented graphically. The results provide a substantial insight in understanding the behavior of FGM rotating disks with constant thickness and different gradient parameter. Furthermore, the stress and deformation state of the disk at constant angular speed and limit angular speed is investigated to explain the existence of optimum gradient parameters.

  6. Navigating the information technology highway: computer solutions to reduce errors and enhance patient safety.

    PubMed

    Koshy, Ranie

    2005-10-01

    Standardized, seamless, integrated information technology in the health-care environment used with other industry tools can markedly decrease preventable errors or adverse events and increase patient safety. According to an Institute of Medicine (IOM) report released in 1999, preventable errors have caused between 44,000 and 98,000 deaths per year. Following the report, President Bill Clinton requested that the Agency of Healthcare Research and Quality, a government agency, look into the issue and fund, at the local or state level, processes that can reduce errors. Funding subsequently was made available for research that utilizes best practice tools in clinical practice to increase patient safety. The Joint Commission on Accreditation of Healthcare Organization has placed a great deal of emphasis on strategies to reduce patient identification errors. Fragmented systems tout the individual as well as enhanced safety applications. These applications, however, are related to prevention in specific conditions and in specific health-care settings. Systems are not integrated with common reference data and common terminology aggregated at a regional or national level to provide access to patient safety risks for timely interventions before errors and adverse events occur. Standardized integrated patient care information systems are not available either on a regional or on a national level. This article examines tangible options to increase patient safety through improved state-of-the-art tools that can be incorporated into the health-care system to prevent errors.

  7. On the efficient and reliable numerical solution of rate-and-state friction problems

    NASA Astrophysics Data System (ADS)

    Pipping, Elias; Kornhuber, Ralf; Rosenau, Matthias; Oncken, Onno

    2016-03-01

    We present a mathematically consistent numerical algorithm for the simulation of earthquake rupture with rate-and-state friction. Its main features are adaptive time stepping, a novel algebraic solution algorithm involving nonlinear multigrid and a fixed point iteration for the rate-and-state decoupling. The algorithm is applied to a laboratory scale subduction zone which allows us to compare our simulations with experimental results. Using physical parameters from the experiment, we find a good fit of recurrence time of slip events as well as their rupture width and peak slip. Computations in 3-D confirm efficiency and robustness of our algorithm.

  8. Bifurcating steady-state solutions of the dissipative quasi-geostrophic equation in Lagrangian formulation

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Min

    2016-10-01

    It is shown that the non-homogeneous dissipative quasi-geostrophic equation ∂θ∂t+uṡ∇θ+κ(-Δ)αθ=sin⁡x2,   u=(-∂x2, ∂x1)(-Δ)-β/2θ with α =0 and β >1 losses stability at a critical value {κc}>0 and this instability gives rise to a circle of steady-state solutions.

  9. Positive periodic solutions of periodic neutral Lotka-Volterra system with state dependent delays

    NASA Astrophysics Data System (ADS)

    Li, Yongkun

    2007-06-01

    By using a fixed point theorem of strict-set-contraction, some new criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with state dependent delays where (i,j=1,2,...,n) are [omega]-periodic functions and (i=1,2,...,n) are [omega]-periodic functions with respect to their first arguments, respectively.

  10. Fully tuneable, Purcell-enhanced solid-state quantum emitters

    SciTech Connect

    Petruzzella, M. Xia, T.; Pagliano, F.; Birindelli, S.; Zobenica, Z.; Fiore, A.; Midolo, L.; Li, L. H.; Linfield, E. H.

    2015-10-05

    We report the full energy control over a semiconductor cavity-emitter system, consisting of single Stark-tunable quantum dots embedded in mechanically reconfigurable photonic crystal membranes. A reversible wavelength tuning of the emitter over 7.5 nm as well as an 8.5 nm mode shift are realized on the same device. Harnessing these two electrical tuning mechanisms, a single exciton transition is brought on resonance with the cavity mode at several wavelengths, demonstrating a ten-fold enhancement of its spontaneous emission. These results open the way to bring several cavity-enhanced emitters mutually into resonance and therefore represent a key step towards scalable quantum photonic circuits featuring multiple sources of indistinguishable single photons.

  11. Analytical solution of steady-state equations for chemical reaction networks with bilinear rate laws.

    PubMed

    Halász, Adám M; Lai, Hong-Jian; McCabe Pryor, Meghan; Radhakrishnan, Krishnan; Edwards, Jeremy S

    2013-01-01

    True steady states are a rare occurrence in living organisms, yet their knowledge is essential for quasi-steady-state approximations, multistability analysis, and other important tools in the investigation of chemical reaction networks (CRN) used to describe molecular processes on the cellular level. Here, we present an approach that can provide closed form steady-state solutions to complex systems, resulting from CRN with binary reactions and mass-action rate laws. We map the nonlinear algebraic problem of finding steady states onto a linear problem in a higher-dimensional space. We show that the linearized version of the steady-state equations obeys the linear conservation laws of the original CRN. We identify two classes of problems for which complete, minimally parameterized solutions may be obtained using only the machinery of linear systems and a judicious choice of the variables used as free parameters. We exemplify our method, providing explicit formulae, on CRN describing signal initiation of two important types of RTK receptor-ligand systems, VEGF and EGF-ErbB1.

  12. Transformation of photophysical properties from solution to solid state in alkoxy-cyano-diphenylacetylene molecules.

    PubMed

    Karunakaran, Venugopal; Prabhu, Deepak D; Das, Suresh; Varughese, Sunil

    2015-07-28

    Detailed photophysical properties of cyano and mono (MA)/bis alkoxy (DA) substituted diphenylacetylene moieties with different alkyl chain lengths (methyl (1), octyl (8) and dodecyl (12)) were investigated in solution and the solid state in an effort to determine the effect of self-aggregation on these properties. The solvated molecules showed a minimal bathochromic shift with an increase of solvent polarity in their absorption spectra, whereas a significant shift was observed in the emission spectra. This could be attributed to the relatively low change in dipole moment between ground and Franck-Condon excited states and luminescence arising from the intramolecular charge transfer state with a dipole moment significantly higher than that of the ground state. In solid state the emission quantum yields of these materials were significantly higher than in solution. For DA1, polymorphic materials with distinct photophysical properties were obtained. The DA1 materials obtained by fast precipitation (DA1) showed broad fluorescence with peaks at 398, 467 and 535 nm upon excitation at different wavelengths. Detailed analysis of absorption, emission and excitation spectra and lifetime experiments indicated that these peaks could be attributed to the monomer, J- and H-type aggregates respectively. Whereas the crystals obtained by slow crystallization (DA1C) showed only one emission peak at around 396 nm attributed to the monomer. This is supported by the single crystal X-ray structure which consists of a monomer molecule having minimal interaction with nearest neighbour molecules.

  13. Analytical Solution of Steady State Equations for Chemical Reaction Networks with Bilinear Rate Laws

    PubMed Central

    Halász, Ádám M.; Lai, Hong-Jian; McCabe, Meghan M.; Radhakrishnan, Krishnan; Edwards, Jeremy S.

    2014-01-01

    True steady states are a rare occurrence in living organisms, yet their knowledge is essential for quasi-steady state approximations, multistability analysis, and other important tools in the investigation of chemical reaction networks (CRN) used to describe molecular processes on the cellular level. Here we present an approach that can provide closed form steady-state solutions to complex systems, resulting from CRN with binary reactions and mass-action rate laws. We map the nonlinear algebraic problem of finding steady states onto a linear problem in a higher dimensional space. We show that the linearized version of the steady state equations obeys the linear conservation laws of the original CRN. We identify two classes of problems for which complete, minimally parameterized solutions may be obtained using only the machinery of linear systems and a judicious choice of the variables used as free parameters. We exemplify our method, providing explicit formulae, on CRN describing signal initiation of two important types of RTK receptor-ligand systems, VEGF and EGF-ErbB1. PMID:24334389

  14. Enhanced recovery pathways in pancreatic surgery: State of the art.

    PubMed

    Pecorelli, Nicolò; Nobile, Sara; Partelli, Stefano; Cardinali, Luca; Crippa, Stefano; Balzano, Gianpaolo; Beretta, Luigi; Falconi, Massimo

    2016-07-28

    Pancreatic surgery is being offered to an increasing number of patients every year. Although postoperative outcomes have significantly improved in the last decades, even in high-volume centers patients still experience significant postoperative morbidity and full recovery after surgery takes longer than we think. In recent years, enhanced recovery pathways incorporating a large number of evidence-based perioperative interventions have proved to be beneficial in terms of improved postoperative outcomes, and accelerated patient recovery in the context of gastrointestinal, genitourinary and orthopedic surgery. The role of these pathways for pancreatic surgery is still unclear as high-quality randomized controlled trials are lacking. To date, non-randomized studies have shown that care pathways for pancreaticoduodenectomy and distal pancreatectomy are safe with no difference in postoperative morbidity, leading to early discharge and no increase in hospital readmissions. Hospital costs are reduced due to better organization of care and resource utilization. However, further research is needed to clarify the effect of enhanced recovery pathways on patient recovery and post-discharge outcomes following pancreatic resection. Future studies should be prospective and follow recent recommendations for the design and reporting of enhanced recovery pathways. PMID:27605881

  15. Enhanced recovery pathways in pancreatic surgery: State of the art

    PubMed Central

    Pecorelli, Nicolò; Nobile, Sara; Partelli, Stefano; Cardinali, Luca; Crippa, Stefano; Balzano, Gianpaolo; Beretta, Luigi; Falconi, Massimo

    2016-01-01

    Pancreatic surgery is being offered to an increasing number of patients every year. Although postoperative outcomes have significantly improved in the last decades, even in high-volume centers patients still experience significant postoperative morbidity and full recovery after surgery takes longer than we think. In recent years, enhanced recovery pathways incorporating a large number of evidence-based perioperative interventions have proved to be beneficial in terms of improved postoperative outcomes, and accelerated patient recovery in the context of gastrointestinal, genitourinary and orthopedic surgery. The role of these pathways for pancreatic surgery is still unclear as high-quality randomized controlled trials are lacking. To date, non-randomized studies have shown that care pathways for pancreaticoduodenectomy and distal pancreatectomy are safe with no difference in postoperative morbidity, leading to early discharge and no increase in hospital readmissions. Hospital costs are reduced due to better organization of care and resource utilization. However, further research is needed to clarify the effect of enhanced recovery pathways on patient recovery and post-discharge outcomes following pancreatic resection. Future studies should be prospective and follow recent recommendations for the design and reporting of enhanced recovery pathways.

  16. Enhanced recovery pathways in pancreatic surgery: State of the art

    PubMed Central

    Pecorelli, Nicolò; Nobile, Sara; Partelli, Stefano; Cardinali, Luca; Crippa, Stefano; Balzano, Gianpaolo; Beretta, Luigi; Falconi, Massimo

    2016-01-01

    Pancreatic surgery is being offered to an increasing number of patients every year. Although postoperative outcomes have significantly improved in the last decades, even in high-volume centers patients still experience significant postoperative morbidity and full recovery after surgery takes longer than we think. In recent years, enhanced recovery pathways incorporating a large number of evidence-based perioperative interventions have proved to be beneficial in terms of improved postoperative outcomes, and accelerated patient recovery in the context of gastrointestinal, genitourinary and orthopedic surgery. The role of these pathways for pancreatic surgery is still unclear as high-quality randomized controlled trials are lacking. To date, non-randomized studies have shown that care pathways for pancreaticoduodenectomy and distal pancreatectomy are safe with no difference in postoperative morbidity, leading to early discharge and no increase in hospital readmissions. Hospital costs are reduced due to better organization of care and resource utilization. However, further research is needed to clarify the effect of enhanced recovery pathways on patient recovery and post-discharge outcomes following pancreatic resection. Future studies should be prospective and follow recent recommendations for the design and reporting of enhanced recovery pathways. PMID:27605881

  17. Understanding the solution phase chemistry and solid state thermodynamic behavior of pharmaceutical cocrystals

    NASA Astrophysics Data System (ADS)

    Maheshwari, Chinmay

    Cocrystals have drawn a lot of research interest in the last decade due to their potential to favorably alter the physicochemical and biopharmaceutical properties of active pharmaceutical ingredients. This dissertation focuses on the thermodynamic stability and solubility of pharmaceutical cocrystals. Specifically, the objectives are to; (i) investigate the influence of coformer properties such as solubility and ionization characteristics on cocrystal solubility and stability as a function of pH, (ii) to measure the thermodynamic solubility of metastable cocrystals, and study the solubility differences measured by kinetic and equilibrium methods, (iii) investigate the role of surfactants on the solubility and synthesis of cocrystals, (iv) investigate the solid state phase transformation of reactants to cocrystals and the factors that influence the reaction kinetics and, (v) provide models that enable the prediction of cocrystal formation by calculating the free energy of formation for a solid to solid transformation of reactants to cocrystals. Cocrystal solubilities were measured directly when cocrystals were thermodynamically stable, while solubilities were calculated from eutectic concentration measurements when cocrystals were of higher solubility than its components. Cocrystal solubility was highly dependent on coformer solubilities for gabapentin-lactam and lamotrigine cocrystals. It was found that melting point is not a good indicator of cocrystal solubility as solute-solvent interactions quantified by the activity coefficient play a huge role in the observed solubility. Similar to salts, cocrystals also exhibit pHmax, however the salts and cocrystals have different dependencies on the parameters that govern the value of pHmax. It is also shown that cocrystals could provide solubility advantage over salts as lamotrigine-nicotinamide cocrystal hydrate has about 6 fold higher solubility relative to lamotrigine-saccharin salt. In the case of mixtures of solid

  18. Steady-state electrodiffusion. Scaling, exact solution for ions of one charge, and the phase plane.

    PubMed Central

    Leuchtag, H R; Swihart, J C

    1977-01-01

    This is the first of two papers dealing with electrodiffusion theory (the Nernst-Planck equation coupled with Gauss's law) and its application to the current-voltage behavior of squid axon. New developments in the exact analysis of the steady-state electrodiffusion problem presented here include (a) a scale transformation that connects a given solution to an infinity of other solutions, suggesting the po-sibility of direct comparison of electrical data for membranes with different thicknesses and other properties; (b) a first-integral relation between the electric field and ion densities more general than analogous relations previously reported, and (c) an exact solution for the homovalent system, i.e., a membrane system permeated by various ion species of the same charge. The latter is a generalization of the known one-ion solution. The properties of the homovalent solution are investigated analytically and graphically. In particular we study the phase-plane curves, which reduce to the parabolas discussed by K. S. Cole in the special case in which the current-density parameter (a linear combination of the ionic current densities) is zero. PMID:831855

  19. Structural characterization of NaOH aqueous solution in the glass and liquid states

    NASA Astrophysics Data System (ADS)

    Bruni, F.; Ricci, M. A.; Soper, A. K.

    2001-05-01

    Using the technique of hydrogen and deuterium substitution, the structure of water in concentrated NaOH solution (10 M) is explored. It is found that major changes in water structure occur both in the liquid phase at T=300 K and in the glassy phase at T=173 K. In particular the 4.4 Å peak in the OO pair correlation function of pure water, which is normally viewed as indicating tetrahedral short-range coordination in water, is totally absent in the NaOH solution at room temperature, and shows up only as a small feature in the NaOH solution in the glassy state. Corresponding changes occur in the OH and HH correlation functions: The hydrogen bond peak position is shifted from 1.85 Å in pure water to 1.65 Å for both the liquid and glassy NaOH, with a reduced number of hydrogen bonds in the glassy phase. The intramolecular HH distance, 1.5 Å, of the water molecule is unaffected by the presence of the solute, but the positions of the peaks in the HH function at 2.4 and 3.8 Å, due to the orientational correlation between neighboring pure water molecules, are respectively, shifted to 2.15 and 3.5 Å. The above findings indicate that ions in aqueous solutions induce a change in water structure equivalent to the application of high pressures.

  20. Direct approach to bound-state solutions of the Yukawa potential

    NASA Astrophysics Data System (ADS)

    Peña, J. J.; Morales, J.; García-Martínez, J.; García-Ravelo, J.

    2015-02-01

    In this work, a straightforward approach to finding bound-state solutions of the Yukawa potential is presented. The proposal essentially converts the Schrödinger equation into a hypergeometric differential equation by means of a coordinate transformation together with a function transformation with the aim of finding the bound-state solutions of the multiparameter exponential-type potentials. The usefulness of the proposal is shown with the study of the bound-state solutions of the Yukawa potential in the frame of the Green and Aldrich approximation to the centrifugal term. Besides that the proposal is by far simpler than procedures developed with the same purpose, our algorithm accepts other kind of approximations to the 1/r2 term as well as the treatment of other specific exponential potentials, which can be obtained using a proper selection of the involved parameters. That is, instead of studying a given exponential-type potential with a specialised method, the energy spectra and wavefunctions are directly obtained as a particular case from the proposal.

  1. Enhanced ozonation degradation of di-n-butyl phthalate by zero-valent zinc in aqueous solution: performance and mechanism.

    PubMed

    Wen, Gang; Wang, Sheng-Jun; Ma, Jun; Huang, Ting-Lin; Liu, Zheng-Qian; Zhao, Lei; Su, Jun-Feng

    2014-01-30

    Enhanced ozonation degradation of di-n-butyl phthalate (DBP) by zero-valent zinc (ZVZ) has been investigated using a semi-continuous reactor in aqueous solution. The results indicated that the combination of ozone (O3) and ZVZ showed an obvious synergetic effect, i.e. an improvement of 54.8% on DBP degradation was obtained by the O3/ZVZ process after 10min reaction compared to the cumulative effect of O3 alone and O2/ZVZ. The degradation efficiency of DBP increased gradually with the increase of ZVZ dosage, enhanced as solution pH increasing from 2.0 to 10.0, and more amount of DBP was degraded with the initial concentration of DBP arising from 0.5 to 2.0mgL(-1). Recycling use of ZVZ resulted in the enhancement of DBP degradation, because the newly formed zinc oxide took part in the reaction. The mechanism investigation demonstrated that the enhancement effect was attributed to the introduction of ZVZ, which could promote the utilization of O3, enhance the formation of superoxide radical by reducing O2 via one-electron transfer, accelerate the production of hydrogen peroxide and the generation of hydroxyl radical. Additionally, the newly formed zinc oxide on ZVZ surface also contributed to the enhancement of DBP degradation in the recycling use of ZVZ. Most importantly, the O3/ZVZ process was also effective in enhanced ozonation degradation of DBP under the background of actual waters.

  2. Enhanced ozonation degradation of di-n-butyl phthalate by zero-valent zinc in aqueous solution: performance and mechanism.

    PubMed

    Wen, Gang; Wang, Sheng-Jun; Ma, Jun; Huang, Ting-Lin; Liu, Zheng-Qian; Zhao, Lei; Su, Jun-Feng

    2014-01-30

    Enhanced ozonation degradation of di-n-butyl phthalate (DBP) by zero-valent zinc (ZVZ) has been investigated using a semi-continuous reactor in aqueous solution. The results indicated that the combination of ozone (O3) and ZVZ showed an obvious synergetic effect, i.e. an improvement of 54.8% on DBP degradation was obtained by the O3/ZVZ process after 10min reaction compared to the cumulative effect of O3 alone and O2/ZVZ. The degradation efficiency of DBP increased gradually with the increase of ZVZ dosage, enhanced as solution pH increasing from 2.0 to 10.0, and more amount of DBP was degraded with the initial concentration of DBP arising from 0.5 to 2.0mgL(-1). Recycling use of ZVZ resulted in the enhancement of DBP degradation, because the newly formed zinc oxide took part in the reaction. The mechanism investigation demonstrated that the enhancement effect was attributed to the introduction of ZVZ, which could promote the utilization of O3, enhance the formation of superoxide radical by reducing O2 via one-electron transfer, accelerate the production of hydrogen peroxide and the generation of hydroxyl radical. Additionally, the newly formed zinc oxide on ZVZ surface also contributed to the enhancement of DBP degradation in the recycling use of ZVZ. Most importantly, the O3/ZVZ process was also effective in enhanced ozonation degradation of DBP under the background of actual waters. PMID:24333716

  3. A study of the system of pyrene and β-cyclodextrin in aqueous solution utilizing the intensity enhancement phenomenon

    NASA Astrophysics Data System (ADS)

    Nakajima, A.

    The system of pyrene and β-cyclodextrin in aqueous solution has been studied by fluorescence spectral measurements. The 1:1 inclusion complex is formed between them. The hydrophobic environment in the β-cyclodextrin cavity has been probed with pyrene exhibiting the intensity enhancement phenomenon. The association constant has been estimated as 190 M -1.

  4. Solution NMR Structure Determination of Polytopic α-Helical Membrane Proteins: A Guide to Spin Label Paramagnetic Relaxation Enhancement Restraints.

    PubMed

    Columbus, Linda; Kroncke, Brett

    2015-01-01

    Solution nuclear magnetic resonance structures of polytopic α-helical membrane proteins require additional restraints beyond the traditional Nuclear Overhauser Effect (NOE) restraints. Several methods have been developed and this review focuses on paramagnetic relaxation enhancement (PRE). Important aspects of spin labeling, PRE measurements, structure calculations, and structural quality are discussed.

  5. Enhanced Internet firewall design using stateful filters final report

    SciTech Connect

    Hutchins, J.A.; Simons, R.W.

    1997-08-01

    The current state-of-the-art in firewall design provides a lot of security for company networks, but normally at the expense of performance and/or functionality. Sandia researched a new approach to firewall design which incorporates a highly stateful approach, allowing much more flexibility for protocol checking and manipulation while retaining performance. A prototype system was built and multiple protocol policy modules implemented to test the concept. The resulting system, though implemented on a low-power workstation, performed almost at the same performance as Sandia`s current firewall.

  6. 44 CFR 201.5 - Enhanced State Mitigation Plans.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... criteria for multi-hazard mitigation measures. (ii) A system to determine the cost effectiveness of... Analysis of Federal Programs, and to rank the measures according to the State's eligibility criteria. (iii... comprehensive, multi-year plan to mitigate the risks posed to existing buildings that have been identified...

  7. Final Report - Montana State University - Microbial Activity and Precipitation at Solution-Solution Mixing Zones in Porous Media

    SciTech Connect

    Gerlach, Robin

    2014-10-31

    Background. The use of biological and chemical processes that degrade or immobilize contaminants in subsurface environments is a cornerstone of remediation technology. The enhancement of biological and chemical processes in situ, involves the transport, displacement, distribution and mixing of one or more reactive agents. Biological and chemical reactions all require diffusive transport of solutes to reaction sites at the molecular scale and accordingly, the success of processes at the meter-scale and larger is dictated by the success of phenomena that occur at the micron-scale. However, current understanding of scaling effects on the mixing and delivery of nutrients in biogeochemically dynamic porous media systems is limited, despite the limitations this imposes on the efficiency and effectiveness of the remediation challenges at hand. Objectives. We therefore proposed to experimentally characterize and computationally describe the growth, evolution, and distribution of microbial activity and mineral formation as well as changes in transport processes in porous media that receive two or more reactive amendments. The model system chosen for this project was based on a method for immobilizing 90Sr, which involves stimulating microbial urea hydrolysis with ensuing mineral precipitation (CaCO3), and co-precipitation of Sr. Studies at different laboratory scales were used to visualize and quantitatively describe the spatial relationships between amendment transport and consumption that stimulate the production of biomass and mineral phases that subsequently modify the permeability and heterogeneity of porous media. Biomass growth, activity, and mass deposition in mixing zones was investigated using two-dimensional micro-model flow cells as well as flow cells that could be analyzed using synchrotron-based x-ray tomography. Larger-scale flow-cell experiments were conducted where the spatial distribution of media properties, flow, segregation of biological activity and

  8. Enhanced repertoire of brain dynamical states during the psychedelic experience.

    PubMed

    Tagliazucchi, Enzo; Carhart-Harris, Robin; Leech, Robert; Nutt, David; Chialvo, Dante R

    2014-11-01

    The study of rapid changes in brain dynamics and functional connectivity (FC) is of increasing interest in neuroimaging. Brain states departing from normal waking consciousness are expected to be accompanied by alterations in the aforementioned dynamics. In particular, the psychedelic experience produced by psilocybin (a substance found in "magic mushrooms") is characterized by unconstrained cognition and profound alterations in the perception of time, space and selfhood. Considering the spontaneous and subjective manifestation of these effects, we hypothesize that neural correlates of the psychedelic experience can be found in the dynamics and variability of spontaneous brain activity fluctuations and connectivity, measurable with functional Magnetic Resonance Imaging (fMRI). Fifteen healthy subjects were scanned before, during and after intravenous infusion of psilocybin and an inert placebo. Blood-Oxygen Level Dependent (BOLD) temporal variability was assessed computing the variance and total spectral power, resulting in increased signal variability bilaterally in the hippocampi and anterior cingulate cortex. Changes in BOLD signal spectral behavior (including spectral scaling exponents) affected exclusively higher brain systems such as the default mode, executive control, and dorsal attention networks. A novel framework enabled us to track different connectivity states explored by the brain during rest. This approach revealed a wider repertoire of connectivity states post-psilocybin than during control conditions. Together, the present results provide a comprehensive account of the effects of psilocybin on dynamical behavior in the human brain at a macroscopic level and may have implications for our understanding of the unconstrained, hyper-associative quality of consciousness in the psychedelic state. PMID:24989126

  9. Enhanced repertoire of brain dynamical states during the psychedelic experience.

    PubMed

    Tagliazucchi, Enzo; Carhart-Harris, Robin; Leech, Robert; Nutt, David; Chialvo, Dante R

    2014-11-01

    The study of rapid changes in brain dynamics and functional connectivity (FC) is of increasing interest in neuroimaging. Brain states departing from normal waking consciousness are expected to be accompanied by alterations in the aforementioned dynamics. In particular, the psychedelic experience produced by psilocybin (a substance found in "magic mushrooms") is characterized by unconstrained cognition and profound alterations in the perception of time, space and selfhood. Considering the spontaneous and subjective manifestation of these effects, we hypothesize that neural correlates of the psychedelic experience can be found in the dynamics and variability of spontaneous brain activity fluctuations and connectivity, measurable with functional Magnetic Resonance Imaging (fMRI). Fifteen healthy subjects were scanned before, during and after intravenous infusion of psilocybin and an inert placebo. Blood-Oxygen Level Dependent (BOLD) temporal variability was assessed computing the variance and total spectral power, resulting in increased signal variability bilaterally in the hippocampi and anterior cingulate cortex. Changes in BOLD signal spectral behavior (including spectral scaling exponents) affected exclusively higher brain systems such as the default mode, executive control, and dorsal attention networks. A novel framework enabled us to track different connectivity states explored by the brain during rest. This approach revealed a wider repertoire of connectivity states post-psilocybin than during control conditions. Together, the present results provide a comprehensive account of the effects of psilocybin on dynamical behavior in the human brain at a macroscopic level and may have implications for our understanding of the unconstrained, hyper-associative quality of consciousness in the psychedelic state.

  10. Characterization of berkelium(III) dipicolinate and borate compounds in solution and the solid state.

    PubMed

    Silver, Mark A; Cary, Samantha K; Johnson, Jason A; Baumbach, Ryan E; Arico, Alexandra A; Luckey, Morgan; Urban, Matthew; Wang, Jamie C; Polinski, Matthew J; Chemey, Alexander; Liu, Guokui; Chen, Kuan-Wen; Van Cleve, Shelley M; Marsh, Matthew L; Eaton, Teresa M; van de Burgt, Lambertus J; Gray, Ashley L; Hobart, David E; Hanson, Kenneth; Maron, Laurent; Gendron, Frédéric; Autschbach, Jochen; Speldrich, Manfred; Kögerler, Paul; Yang, Ping; Braley, Jenifer; Albrecht-Schmitt, Thomas E

    2016-08-26

    Berkelium is positioned at a crucial location in the actinide series between the inherently stable half-filled 5f(7) configuration of curium and the abrupt transition in chemical behavior created by the onset of a metastable divalent state that starts at californium. However, the mere 320-day half-life of berkelium's only available isotope, (249)Bk, has hindered in-depth studies of the element's coordination chemistry. Herein, we report the synthesis and detailed solid-state and solution-phase characterization of a berkelium coordination complex, Bk(III)tris(dipicolinate), as well as a chemically distinct Bk(III) borate material for comparison. We demonstrate that berkelium's complexation is analogous to that of californium. However, from a range of spectroscopic techniques and quantum mechanical calculations, it is clear that spin-orbit coupling contributes significantly to berkelium's multiconfigurational ground state. PMID:27563098

  11. A modified two-state empirical valence bond model for proton transport in aqueous solutions

    SciTech Connect

    Mabuchi, Takuya; Fukushima, Akinori; Tokumasu, Takashi

    2015-07-07

    A detailed analysis of the proton solvation structure and transport properties in aqueous solutions is performed using classical molecular dynamics simulations. A refined two-state empirical valence bond (aTS-EVB) method, which is based on the EVB model of Walbran and Kornyshev and the anharmonic water force field, is developed in order to describe efficiently excess proton transport via the Grotthuss mechanism. The new aTS-EVB model clearly satisfies the requirement for simpler and faster calculation, because of the simplicity of the two-state EVB algorithm, while providing a better description of diffusive dynamics of the excess proton and water in comparison with the previous two-state EVB models, which significantly improves agreement with the available experimental data. The results of activation energies for the excess proton and water calculated between 300 and 340 K (the temperature range used in this study) are also found to be in good agreement with the corresponding experimental data.

  12. Steady-state solutions of a diffusive energy-balance climate model and their stability

    NASA Technical Reports Server (NTRS)

    Ghil, M.

    1975-01-01

    A diffusive energy-balance climate model, governed by a nonlinear parabolic partial differential equation, was studied. Three positive steady-state solutions of this equation are found; they correspond to three possible climates of our planet: an interglacial (nearly identical to the present climate), a glacial, and a completely ice-covered earth. Models similar to the main one are considered, and the number of their steady states was determined. All the models have albedo continuously varying with latitude and temperature, and entirely diffusive horizontal heat transfer. The stability under small perturbations of the main model's climates was investigated. A stability criterion is derived, and its application shows that the present climate and the deep freeze are stable, whereas the model's glacial is unstable. The dependence was examined of the number of steady states and of their stability on the average solar radiation.

  13. Critical field enhancement of asymptotic optical bound states in the continuum.

    PubMed

    Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert

    2015-01-01

    We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 10(8) are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications. PMID:26673548

  14. Critical field enhancement of asymptotic optical bound states in the continuum

    NASA Astrophysics Data System (ADS)

    Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert

    2015-12-01

    We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 108 are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications.

  15. Critical field enhancement of asymptotic optical bound states in the continuum

    PubMed Central

    Yoon, Jae Woong; Song, Seok Ho; Magnusson, Robert

    2015-01-01

    We study spectral singularities and critical field enhancement factors associated with embedded photonic bound states in subwavelength periodic Si films. Ultrahigh-Q resonances supporting field enhancement factor exceeding 108 are obtained in the spectral vicinity of exact embedded eigenvalues in spite of deep surface modulation and vertical asymmetry of the given structure. Treating relations between the partial resonance Q and field enhancement factors with an analytical coupled-mode model, we derive a general strategy to maximize the field enhancement associated with these photonic bound states in the presence of material dissipation. The analytical expression for the field enhancement quantitatively agrees with rigorous numerical calculations. Therefore, our results provide a general knowledge for designing practical resonance elements based on optical bound states in the continuum in various applications. PMID:26673548

  16. Creation of Novel Solid-Solution Alloy Nanoparticles on the Basis of Density-of-States Engineering by Interelement Fusion.

    PubMed

    Kobayashi, Hirokazu; Kusada, Kohei; Kitagawa, Hiroshi

    2015-06-16

    Currently 118 known elements are represented in the periodic table. Of these 118 elements, only about 80 elements are stable, nonradioactive, and widely available for our society. From the viewpoint of the "elements strategy", we need to make full use of the 80 elements to bring out their latent ability and create innovative materials. Furthermore, there is a strong demand that the use of rare or toxic elements be reduced or replaced while their important properties are retained. Advanced science and technology could create higher-performance materials even while replacing or reducing minor or harmful elements through the combination of more abundant elements. The properties of elements are correlated directly with their electronic states. In a solid, the magnitude of the density of states (DOS) at the Fermi level affects the physical and chemical properties. In the present age, more attention has been paid to improving the properties of materials by means of alloying elements. In particular, the solid-solution-type alloy is advantageous because the properties can be continuously controlled by tuning the compositions and/or combinations of the constituent elements. However, the majority of bulk alloys are of the phase-separated type under ambient conditions, where constituent elements are immiscible with each other. To overcome the challenge of the bulk-phase metallurgical aspects, we have focused on the nanosize effect and developed methods involving "nonequilibrium synthesis" or "a process of hydrogen absorption/desorption". We propose a new concept of "density-of-states engineering" for the design of materials having the most desirable and suitable properties by means of "interelement fusion". In this Account, we describe novel solid-solution alloys of Pd-Pt, Ag-Rh, and Pd-Ru systems in which the constituent elements are immiscible in the bulk state. The homogeneous solid-solution alloys of Pd and Pt were created from Pd core/Pt shell nanoparticles using a

  17. Creation of Novel Solid-Solution Alloy Nanoparticles on the Basis of Density-of-States Engineering by Interelement Fusion.

    PubMed

    Kobayashi, Hirokazu; Kusada, Kohei; Kitagawa, Hiroshi

    2015-06-16

    Currently 118 known elements are represented in the periodic table. Of these 118 elements, only about 80 elements are stable, nonradioactive, and widely available for our society. From the viewpoint of the "elements strategy", we need to make full use of the 80 elements to bring out their latent ability and create innovative materials. Furthermore, there is a strong demand that the use of rare or toxic elements be reduced or replaced while their important properties are retained. Advanced science and technology could create higher-performance materials even while replacing or reducing minor or harmful elements through the combination of more abundant elements. The properties of elements are correlated directly with their electronic states. In a solid, the magnitude of the density of states (DOS) at the Fermi level affects the physical and chemical properties. In the present age, more attention has been paid to improving the properties of materials by means of alloying elements. In particular, the solid-solution-type alloy is advantageous because the properties can be continuously controlled by tuning the compositions and/or combinations of the constituent elements. However, the majority of bulk alloys are of the phase-separated type under ambient conditions, where constituent elements are immiscible with each other. To overcome the challenge of the bulk-phase metallurgical aspects, we have focused on the nanosize effect and developed methods involving "nonequilibrium synthesis" or "a process of hydrogen absorption/desorption". We propose a new concept of "density-of-states engineering" for the design of materials having the most desirable and suitable properties by means of "interelement fusion". In this Account, we describe novel solid-solution alloys of Pd-Pt, Ag-Rh, and Pd-Ru systems in which the constituent elements are immiscible in the bulk state. The homogeneous solid-solution alloys of Pd and Pt were created from Pd core/Pt shell nanoparticles using a

  18. Hydrodynamics of steady state phloem transport with radial leakage of solute

    PubMed Central

    Cabrita, Paulo; Thorpe, Michael; Huber, Gregor

    2013-01-01

    Long-distance phloem transport occurs under a pressure gradient generated by the osmotic exchange of water associated with solute exchange in source and sink regions. But these exchanges also occur along the pathway, and yet their physiological role has almost been ignored in mathematical models of phloem transport. Here we present a steady state model for transport phloem which allows solute leakage, based on the Navier-Stokes and convection-diffusion equations which describe fluid motion rigorously. Sieve tube membrane permeability Ps for passive solute exchange (and correspondingly, membrane reflection coefficient) influenced model results strongly, and had to lie in the bottom range of the values reported for plant cells for the results to be realistic. This smaller permeability reflects the efficient specialization of sieve tube elements, minimizing any diffusive solute loss favored by the large concentration difference across the sieve tube membrane. We also found there can be a specific reflection coefficient for which pressure profiles and sap velocities can both be similar to those predicted by the Hagen-Poiseuille equation for a completely impermeable tube. PMID:24409189

  19. Photofragmentation, state interaction, and energetics of Rydberg and ion-pair states: Resonance enhanced multiphoton ionization of HI

    SciTech Connect

    Hróðmarsson, Helgi Rafn; Wang, Huasheng; Kvaran, Ágúst

    2014-06-28

    Mass resolved resonance enhanced multiphoton ionization data for hydrogen iodide (HI), for two-photon resonance excitation to Rydberg and ion-pair states in the 69 600–72 400 cm{sup −1} region were recorded and analyzed. Spectral perturbations due to homogeneous and heterogeneous interactions between Rydberg and ion-pair states, showing as deformations in line-positions, line-intensities, and line-widths, were focused on. Parameters relevant to photodissociation processes, state interaction strengths and spectroscopic parameters for deperturbed states were derived. Overall interaction and dynamical schemes to describe the observations are proposed.

  20. Solid-State Recorders Enhance Scientific Data Collection

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Under Small Business Innovation Research (SBIR) contracts with Goddard Space Flight Center, SEAKR Engineering Inc., of Centennial, Colorado, crafted a solid-state recorder (SSR) to replace the tape recorder onboard a Spartan satellite carrying NASA's Inflatable Antenna Experiment. Work for that mission and others has helped SEAKR become the world leader in SSR technology for spacecraft. The company has delivered more than 100 systems, more than 85 of which have launched onboard NASA, military, and commercial spacecraft including imaging satellites that provide much of the high-resolution imagery for online mapping services like Google Earth.

  1. Enhanced arbitrated quantum signature scheme using Bell states

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Liu, Jian-Wei; Shang, Tao

    2014-06-01

    We investigate the existing arbitrated quantum signature schemes as well as their cryptanalysis, including intercept-resend attack and denial-of-service attack. By exploring the loopholes of these schemes, a malicious signatory may successfully disavow signed messages, or the receiver may actively negate the signature from the signatory without being detected. By modifying the existing schemes, we develop counter-measures to these attacks using Bell states. The newly proposed scheme puts forward the security of arbitrated quantum signature. Furthermore, several valuable topics are also presented for further research of the quantum signature scheme.

  2. Soil and soil solution chemistry under red spruce stands across the northeastern united states

    USGS Publications Warehouse

    David, M.B.; Lawrence, G.B.

    1996-01-01

    Red spruce ecosystems in the northeastern United States are of interest because this species is undergoing regional decline. Their underlying soils have been examined closely at only a few sites, and information available on red spruce soils throughout this region is limited.This study was conducted to examine soil and soil solution chemistry at red spruce sites in the northeastern US that encompass the range of soil conditions in which red spruce grow. Soils and soil solutions from Oa and B horizons were obtained over a 2-year period from 12 undisturbed red spruce forests (elevations of 80-975 m) in New York, Vermont, New Hampshire, and Maine. All sites had extremely acid Spodosols (Oa soil pH range 2.56 to 3.11 in 0.01 M CaCl2), with generally low concentrations of base cations and high concentrations of Al on soil exchange sites. There was considerable range in exchange chemistry across the sites, however, with exchangeable Ca in Oa horizons ranging from 2.1 to 21.6 cmolckg-1 and exchangeable Al from 3.6 to 18.3 cmolckg-1. Solution chemistry had high concentrations of DOC in the Oa horizons (1160-15200 ??mol L-1), with higher concentrations in the fall than in the spring, which was probably a reflection of fresh litter inputs. Despite high concentrations of DOC in all solutions, inorganic Al was found in some Oa solutions at concentrations as high as 26 ??mol L-1. Ratios of Ca2+ to inorganic Al concentraturns were less than 1.0 in the Oa horizon of one site, and were well below 1.0 in B horizons of all sites. That soil chemistry was related to soil solution chemistry was demonstrated by solution Al concentrations in the forest floor having significant relationships with pyrophosphate extractable Al, although it was not related in the B horizon. Soil exchangeable Ca/Al ratios in the Oa horizon explained 75% of the variation in solution Ca2+/inorganic Al ratios when mean values were used for each site. Our studies have expanded the range of soil chemical

  3. The transverse magnetic field effect on steady-state solutions of the Bursian diode

    SciTech Connect

    Pramanik, Sourav; Chakrabarti, Nikhil

    2015-04-15

    A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.

  4. Characterization of Swollen States of Polyelectrolyte Brushes in Salt Solution by Neutron Reflectivity

    NASA Astrophysics Data System (ADS)

    Kobayashi, Motoyasu; Mitamura, Koji; Terada, Masami; Yamada, Norifumi L.; Takahara, Atsushi

    2011-01-01

    Cationic and zwitterionic polyelectrolyte brushes on quartz substrate were synthesized by surface-initiated atom transfer radical polymerization of 2-(methacryloyloxy)-ethyltrimethylammonium chloride (MTAC) and 2-(methacryloyloxy)ethyl phosphorylcholine (MPC). The effects of ionic strength on brush structure are investigated by neutron reflectivity (NR) in NaCl deuterium oxide (D2O) solutions. We observed that poly(MTAC) chains were drastically shrunk at concentrations above 0.1 M NaCl/D2O, which may be the change in charge-screening effect against ions on poly(MTAC). On the other hand, effect of salt concentration on a swollen state of poly(MPC) brush was negligible, even at the high concentration (5.0 M) close to saturation. The behaviour of poly(MPC) in salt aqueous solution is completely different from that of poly(MTAC), which may arise from the unique interaction properties, neutral nature, and hydrated water structure of phosphorylcholine units.

  5. Steady-state solutions for relativistically strong electromagnetic waves in plasmas.

    NASA Technical Reports Server (NTRS)

    Max, C. E.

    1973-01-01

    New steady-state solutions are derived which describe electromagnetic waves strong enough to make plasma ions and electrons relativistic. A two-fluid model is used throughout. The following solutions are studied: (1) linearly polarized waves with phase velocity much greater than c; (2) arbitrarily polarized waves with phase velocity near c, in a cold uniform plasma; (3) circularly polarized waves in a uniform plasma characterized by a scalar pressure tensor. All of these waves are capable of propagating in normally overdense plasmas, due to nonlinearities introduced by relativistic effects. The propagation of relativistically strong waves in a density gradient is examined, for the example of a circularly polarized wave strong enough to make electrons but not ions relativistic. It is shown that such a wave propagates at constant energy flux despite the nonlinearity of the system.

  6. The transverse magnetic field effect on steady-state solutions of the Bursian diode

    NASA Astrophysics Data System (ADS)

    Pramanik, Sourav; Ender, A. Ya.; Kuznetsov, V. I.; Chakrabarti, Nikhil

    2015-04-01

    A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.

  7. Surface corrosion enhancement of passive films on NiTi shape memory alloy in different solutions.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-06-01

    The corrosion behaviors of NiTi shape memory alloy in NaCl solution, H2SO4 solution and borate buffer solution were investigated. It was found that TiO2 in passive film improved the corrosion resistance of NiTi shape memory. However, low corrosion resistance of passive film was observed in low pH value acidic solution due to TiO2 dissolution. Moreover, the corrosion resistance of NiTi shape memory alloy decreased with the increasing of passivated potential in the three solutions. The donor density in passive film increased with the increasing of passivated potential. Different solutions affect the semiconductor characteristics of the passive film. The reducing in the corrosion resistance was attributed to the more donor concentrations in passive film and thinner thickness of the passive film.

  8. 1H-detected 13C Photo-CIDNP as a Sensitivity Enhancement Tool in Solution NMR

    PubMed Central

    Lee, Jung Ho; Sekhar, Ashok; Cavagnero, Silvia

    2011-01-01

    NMR is a powerful yet intrinsically insensitive technique. The applicability of NMR to chemical and biological systems would be substantially extended by new approaches going beyond current signal-to-noise capabilities. Here, we exploit the large enhancements arising from 13C photo-chemically induced dynamic nuclear polarization (13C photo-CIDNP) in solution to improve biomolecular NMR sensitivity in the context of heteronuclear correlation spectroscopy. The 13C-PRINT pulse sequence presented here involves an initial 13C nuclear spin polarization via photo-CIDNP followed by conversion to antiphase coherence and transfer to 1H for detection. We observe substantial enhancements, up to ≫200-fold, relative to the dark (laser off) experiment. Resonances of both side-chain and backbone CH pairs are enhanced for the three aromatic residues Trp, His and Tyr and the Trp-containing σ32 peptide. The sensitivity of this experiment, defined as signal-to-noise per unit time (S/N)t, is unprecedented in the NMR polarization enhancement literature dealing with polypeptides in solution. Up to a 16-fold larger (S/N)t than the 1H-13C SE-HSQC reference sequence is achieved, for the σ32 peptide. This gain leads to a reduction in data collection time up to 256-fold, highlighting the advantages of 1H-detected 13C photo-CIDNP in solution NMR. PMID:21548581

  9. Is solid-state NMR enhanced by dynamic nuclear polarization?

    PubMed

    Lee, Daniel; Hediger, Sabine; De Paëpe, Gaël

    2015-01-01

    The recent trend of high-field (~5-20 T), low-temperature (~100 K) ssNMR combined with dynamic nuclear polarization (DNP) under magic angle spinning (MAS) conditions is analyzed. A brief overview of the current theory of hyperpolarization for so-called MAS-DNP experiments is given, along with various reasons why the DNP-enhancement, the ratio of the NMR signal intensities obtained in the presence and absence of microwave irradiation suitable for hyperpolarization, should not be used alone to gauge the value of performing MAS-DNP experiments relative to conventional ssNMR. This is demonstrated through a dissection of the current conditions required for MAS-DNP with particular attention to resulting absolute sensitivities and spectral resolution. Consequently, sample preparation methods specifically avoiding the surplus of glass-forming solvents so as to improve the absolute sensitivity and resolution are discussed, as are samples that are intrinsically pertinent for MAS-DNP studies (high surface area, amorphous, and porous). Owing to their pertinence, examples of recent applications on these types of samples where chemically-relevant information has been obtained that would have been impossible without the sensitivity increases bestowed by MAS-DNP are also detailed. Additionally, a promising further implementation for MAS-DNP is exampled, whereby the sensitivity improvements shown for (correlation) spectroscopy of nuclei at low natural isotopic abundance, facilitate internuclear distance measurements, especially for long distances (absence of dipolar truncation). Finally, we give some speculative perspectives for MAS-DNP.

  10. Michigan State University. Strategy without Deep Pockets: Enhancing Institutional Capacity from Within. Exemplars.

    ERIC Educational Resources Information Center

    Wegner, Gregory

    This paper describes the solution developed by Michigan State University to increase the institutions capacity for strategic innovation while respecting the Universitys limited financial means. One element of Michigan States strategy has been to send cross-institutional teams to participate in the Knight Collaboratives Wharton-IRHE (Institute for…

  11. Why do co-solvents enhance the solubility of solutes in supercritical fluids? New evidence and opinion.

    PubMed

    Zhang, Xiaogang; Han, Buxing; Hou, Zhenshan; Zhang, Jianling; Liu, Zhimin; Jiang, Tao; He, Jun; Li, Hongping

    2002-11-15

    The effects of two polar co-solvents, chlorodifluoromethane and acetone, on the solubility and enthalpy of a solution of 1,4-naphthoquinone in supercritical (SC) CO2 were studied. We found that the dissolution process becomes less exothermic in the presence of the co-solvents relative to that in pure CO2, although the solubility is enhanced significantly by the co-solvents. This indicates that the increase in the solubility by adding co-solvents results from the increase of the entropy of solution. On the basis of the unexpected results we propose a new mechanism for the solubility enhancement of the solute by the co-solvents in supercritical fluids (SCF); this should be applicable to cases in which the local density of the SC solvent around the solute and the co-solvent is larger, and the co-solvent associates preferentially with the solute. The results are also very important for the understanding of other fundamental questions of SCF science, such as the effect of co-solvents on the thermodynamic and kinetic properties of the reactions in SCFs.

  12. Synthesis of silver particles on copper substrates using ethanol-based solution for surface-enhanced Raman spectroscopy

    SciTech Connect

    Chen, Li Zhang, Zuojun; Chen, Gang; Zhou, Hui; Lai, Chunhong

    2014-03-15

    The displacement reaction of AgNO{sub 3} and copper metal is an effective and economical way to fabricate Ag-Cu surface enhanced Raman scattering (SERS) substrates. Aqueous solutions of AgNO{sub 3} are usually used for substrate preparation. In this work, a new method for Ag-Cu SERS substrate preparation is proposed, which uses an ethanol solution rather than an aqueous AgNO{sub 3} solution. Analysis of the surface morphologies of sample substrates by field emission scanning electron microscopy (FESEM) showed that the silver nanoparticles prepared by this new method were more regular than those prepared in the traditional aqueous solution. The SERS spectra of Rhodamine 6G (R6G) adsorbed on these Ag-Cu substrates were then investigated and compared. It was found that the Ag-Cu substrates prepared by this method provide significant improvements in Raman signal sensitivity and large-area uniformity. The enhancement factor of this new substrate is about 330 times higher than that prepared using an aqueous AgNO{sub 3} solution under identical experimental conditions. It was also found that 70% of the original sensitivity of the substrate remains after 15 days of exposure to air.

  13. Synthesis of silver particles on copper substrates using ethanol-based solution for surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Li; Zhang, Zuojun; Chen, Gang; Lai, Chunhong; Zhou, Hui

    2014-03-01

    The displacement reaction of AgNO3 and copper metal is an effective and economical way to fabricate Ag-Cu surface enhanced Raman scattering (SERS) substrates. Aqueous solutions of AgNO3 are usually used for substrate preparation. In this work, a new method for Ag-Cu SERS substrate preparation is proposed, which uses an ethanol solution rather than an aqueous AgNO3 solution. Analysis of the surface morphologies of sample substrates by field emission scanning electron microscopy (FESEM) showed that the silver nanoparticles prepared by this new method were more regular than those prepared in the traditional aqueous solution. The SERS spectra of Rhodamine 6G (R6G) adsorbed on these Ag-Cu substrates were then investigated and compared. It was found that the Ag-Cu substrates prepared by this method provide significant improvements in Raman signal sensitivity and large-area uniformity. The enhancement factor of this new substrate is about 330 times higher than that prepared using an aqueous AgNO3 solution under identical experimental conditions. It was also found that 70% of the original sensitivity of the substrate remains after 15 days of exposure to air.

  14. Enhanced Solid-State Biogas Production from Lignocellulosic Biomass by Organosolv Pretreatment

    PubMed Central

    Mirmohamadsadeghi, Safoora; Zamani, Akram; Horváth, Ilona Sárvári

    2014-01-01

    Organosolv pretreatment was used to improve solid-state anaerobic digestion (SSAD) for methane production from three different lignocellulosic substrates (hardwood elm, softwood pine, and agricultural waste rice straw). Pretreatments were conducted at 150 and 180°C for 30 and 60 min using 75% ethanol solution as an organic solvent with addition of sulfuric acid as a catalyst. The statistical analyses showed that pretreatment temperature was the significant factor affecting methane production. Optimum temperature was 180°C for elmwood while it was 150°C for both pinewood and rice straw. Maximum methane production was 152.7, 93.7, and 71.4 liter per kg carbohydrates (CH), which showed up to 32, 73, and 84% enhancement for rice straw, elmwood, and pinewood, respectively, compared to those from the untreated substrates. An inverse relationship between the total methane yield and the lignin content of the substrates was observed. Kinetic analysis of the methane production showed that the process followed a first-order model for all untreated and pretreated lignocelluloses. PMID:25243134

  15. Steady-state axisymmetric nonlinear magnetohydrodynamic solutions with various boundary conditions

    NASA Astrophysics Data System (ADS)

    Wang, Lile; Lou, Yu-Qing

    2014-04-01

    Axisymmetric magnetohydrodynamics (MHD) can be invoked for describing astrophysical magnetized flows and formulated to model stellar magnetospheres including main-sequence stars (e.g. the Sun), compact stellar objects [e.g. magnetic white dwarfs (MWDs), radio pulsars, anomalous X-ray pulsars, magnetars, isolated neutron stars, etc.] and planets as a major step forward towards a full three-dimensional model construction. Using powerful and reliable numerical solvers based on two distinct finite-difference method and finite-element method schemes of algorithm, we examine axisymmetric steady-state or stationary MHD models in Throumoulopoulos & Tasso, finding that their separable semi-analytic non-linear solutions are actually not unique given their specific selection of several free functionals and chosen boundary conditions. Similar situations of multiple non-linear solutions with the same boundary conditions actually also happen to force-free magnetic field models of Low & Lou. The multiplicity of non-linear steady MHD solutions gives rise to differences in the total energies contained in the magnetic fields and flow velocity fields as well as in the asymptotic behaviours approaching infinity, which may in turn explain why numerical solvers tend to converge to a non-linear solution with a lower energy than the corresponding separable semi-analytic one. By properly adjusting model parameters, we invoke semi-analytic and numerical solutions to describe different kinds of scenarios, including nearly parallel case and the situation in which the misalignment between the plasma flow and magnetic field is considerable. We propose that these MHD models are capable of describing the magnetospheres of MWDs as examples of applications with moderate conditions (including magnetic field) where the typical values of several important parameters are consistent with observations. Physical parameters can also be estimated based on such MHD models directly. We discuss the challenges

  16. Self-regulating genes. Exact steady state solution by using Poisson representation

    NASA Astrophysics Data System (ADS)

    Sugár, István P.; Simon, István

    2014-09-01

    Systems biology studies the structure and behavior of complex gene regulatory networks. One of its aims is to develop a quantitative understanding of the modular components that constitute such networks. The self-regulating gene is a type of auto regulatory genetic modules which appears in over 40% of known transcription factors in E. coli. In this work, using the technique of Poisson Representation, we are able to provide exact steady state solutions for this feedback model. By using the methods of synthetic biology (P.E.M. Purnick and Weiss, R., Nature Reviews, Molecular Cell Biology, 2009, 10: 410-422) one can build the system itself from modules like this.

  17. Zirconium complexes with lactic acid in the solution and solid states

    NASA Astrophysics Data System (ADS)

    Demkowicz, Paul Andrew

    Lactic acid complexes of zirconium are used in a great number of industrial applications. Among these is their use as crosslinking agents for hydraulic fracturing fluids used in secondary oil recovery operations. Because of a poor understanding of zirconium lactate complex chemistry and crosslinking reactions, however, the design of superior fluid systems is often not guided by sound chemical principles and leads to empirical guesswork. Zirconium lactate solutions were characterized using Fourier transform infrared (FT-IR) spectroscopy, 1H, 13C, and 17O nuclear magnetic resonance (NMR) spectroscopy, and potentiometry. The results indicate that lactic acid is coordinated bidentate to zirconium via the alcohol and carboxylate groups. The average number of lactate ligands per zirconium ion is approximately 2 and is demonstrated to be relatively constant from pH 4--9. The lability of the lactate complexes increases as the pH is decreased. The NMR data reveal that there are both large and small complex molecules present in solution, with the size of the complex depending on the extent of zirconium hydrolysis. Large complexes consist of lactic acid coordinated to polynuclear zirconium hydroxy ions. The molecular size of these complexes is sufficient to hinder their tumbling in solution and cause broadening of the measured NMR signals. Small complexes involve lactic acid coordinated to hydroxylated species containing fewer zirconium ions, such that the rotational motion in solution is sufficiently rapid to result in narrow NMR signals. Zirconium lactate complexes were precipitated from solution and analyzed in the solid state using FT-IR spectroscopy, 13C magic angle spinning (MAS) NMR spectroscopy, elemental analysis, thermal gravitational analysis, and x-ray diffraction. Two distinct types of crystalline compounds were synthesized with four lactate ligands per zirconium ion. The coordination of lactic acid to zirconium is different in the two compounds, with one showing

  18. A Solution Space for a System of Null-State Partial Differential Equations: Part 3

    NASA Astrophysics Data System (ADS)

    Flores, Steven M.; Kleban, Peter

    2015-01-01

    This article is the third of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations (PDEs) in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE κ ). The system comprises 2 N null-state equations and three conformal Ward identities that govern CFT correlation functions of 2 N one-leg boundary operators. In the first two articles (Flores and Kleban, in Commun Math Phys, arXiv:1212.2301, 2012; Commun Math Phys, arXiv:1404.0035, 2014), we use methods of analysis and linear algebra to prove that dim , with C N the Nth Catalan number. Extending these results, we prove in this article that dim and entirely consists of (real-valued) solutions constructed with the CFT Coulomb gas (contour integral) formalism. In order to prove this claim, we show that a certain set of C N such solutions is linearly independent. Because the formulas for these solutions are complicated, we prove linear independence indirectly. We use the linear injective map of Lemma 15 in Flores and Kleban (Commun Math Phys, arXiv:1212.2301, 2012) to send each solution of the mentioned set to a vector in , whose components we find as inner products of elements in a Temperley-Lieb algebra. We gather these vectors together as columns of a symmetric matrix, with the form of a meander matrix. If the determinant of this matrix does not vanish, then the set of C N Coulomb gas solutions is linearly independent. And if this determinant does vanish, then we construct an alternative set of C N Coulomb gas solutions and follow a similar procedure to show that this set is linearly independent. The latter situation is closely related to CFT minimal models. We emphasize that, although the system of PDEs arises in CFT in away that is typically non-rigorous, our treatment of this system here and in Flores and Kleban (Commun Math Phys, arXiv:1212.2301, 2012; Commun Math Phys, arXiv:1404

  19. Enhancing Science Teaching through Performing Marbling Art Using Basic Solutions and Base Indicators

    ERIC Educational Resources Information Center

    Çil, Emine; Çelik, Kevser; Maçin, Tuba; Demirbas, Gülay; Gökçimen, Özlem

    2014-01-01

    Basic solutions are an indispensable part of our daily life. Basic solutions are commonly used in industries such as the textile industry, oil refineries, the fertilizer industry, and pharmaceutical products. Most cleaning agents, such as soap, detergent, and bleach, and some of our foods, such as chocolate and eggs, include bases. Bases are the…

  20. Dynamic characterization of hydrophobic and hydrophilic solutes in oleic-acid enhanced transdermal delivery using two-photon fluorescence microscopy

    SciTech Connect

    Tseng, Te-Yu; Yang, Chiu-Sheng; Chen, Yang-Fang; Tsai, Tsung-Hua; Dong, Chen-Yuan

    2014-10-20

    In this letter, we propose an efficient methodology of investigating dynamic properties of sulforhodamine B and rhodamine B hexyl ester molecules transporting across ex-vivo human stratum corneum with and without oleic acid enhancement. Three-dimensional, time-lapse fluorescence images of the stratum corneum can be obtained using two-photon fluorescence microscopy. Furthermore, temporal quantifications of transport enhancements in diffusion parameters can be achieved with the use of Fick's second law. Dynamic characterization of solutes transporting across the stratum corneum is an effective method for understanding transient phenomena in transdermal delivery of probe molecules, leading to improved delivery strategies of molecular species for therapeutic purposes.

  1. Prospects for enhanced oil recovery in the United States

    SciTech Connect

    Claridge, E.L.

    1982-08-01

    It appears that only one third of the crude oil discovered in the United States will be recovered by primary and secondary recovery methods. The application of tertiary recovery methods is not proceeding at a rate sufficient to prevent the abandonment of about 250 billion barrels at a rate of about 10 billion barrels per year, which has begun and will continue unless significant steps are taken, either to make tertiary recovery more immediately attractive or to ''moth-ball'' the oil fields and their leases and operating unit agreements until economic conditions are made more favorable. The current status and prospects of each major process are examined. The reasons why thermal recovery is the principal process at present, but is unable to expand much, why CO/sub 2/ flooding is about to begin on a large scale but not in many places where it would be applicable, and why chemical flooding has lost promise even though it is needed for most of the fields nearing abandonment, are discussed. It appears likely that no more than 15 billion barrels will be recovered by EOR processes by 2000 A.D.

  2. Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz.

    PubMed

    Sousa, Eduardo Gomes Rodrigues de; Carvalho, Erika Martins de; San Gil, Rosane Aguiar da Silva; Santos, Tereza Cristina Dos; Borré, Leandro Bandeira; Santos-Filho, Osvaldo Andrade; Ellena, Javier

    2016-09-01

    Samples of efavirenz (EFZ) were evaluated to investigate the influence of the micronization process on EFZ stability. A combination of X-ray diffraction, thermal analysis, FTIR, observations of isotropic chemical shifts of (1)H in distinct solvents, their temperature dependence and spin-lattice relaxation time constants (T1), solution (1D and 2D) (13)C nuclear magnetic resonance (NMR), and solid-state (13)C NMR (CPMAS NMR) provides valuable structural information and structural elucidation of micronized EFZ and heptane-recrystallized polymorphs (EFZ/HEPT). This study revealed that the micronization process did not affect the EFZ crystalline structure. It was observed that the structure of EFZ/HEPT is in the same form as that obtained from ethyl acetate/hexane, as shown in the literature. A comparison of the solid-state NMR spectra revealed discrepancies regarding the assignments of some carbons published in the literature that have been resolved.

  3. Implicit unified gas-kinetic scheme for steady state solutions in all flow regimes

    NASA Astrophysics Data System (ADS)

    Zhu, Yajun; Zhong, Chengwen; Xu, Kun

    2016-06-01

    This paper presents an implicit unified gas-kinetic scheme (UGKS) for non-equilibrium steady state flow computation. The UGKS is a direct modeling method for flow simulation in all regimes with the updates of both macroscopic flow variables and microscopic gas distribution function. By solving the macroscopic equations implicitly, a predicted equilibrium state can be obtained first through iterations. With the newly predicted equilibrium state, the evolution equation of the gas distribution function and the corresponding collision term can be discretized in a fully implicit way for fast convergence through iterations as well. The lower-upper symmetric Gauss-Seidel (LU-SGS) factorization method is implemented to solve both macroscopic and microscopic equations, which improves the efficiency of the scheme. Since the UGKS is a direct modeling method and its physical solution depends on the mesh resolution and the local time step, a physical time step needs to be fixed before using an implicit iterative technique with a pseudo-time marching step. Therefore, the physical time step in the current implicit scheme is determined by the same way as that in the explicit UGKS for capturing the physical solution in all flow regimes, but the convergence to a steady state speeds up through the adoption of a numerical time step with large CFL number. Many numerical test cases in different flow regimes from low speed to hypersonic ones, such as the Couette flow, cavity flow, and the flow passing over a cylinder, are computed to validate the current implicit method. The overall efficiency of the implicit UGKS can be improved by one or two orders of magnitude in comparison with the explicit one.

  4. Vibrational and electronic spectroscopy of the retro-carotenoid rhodoxanthin in avian plumage, solid-state films, and solution.

    PubMed

    Berg, Christopher J; LaFountain, Amy M; Prum, Richard O; Frank, Harry A; Tauber, Michael J

    2013-11-15

    Rhodoxanthin is one of few retro-carotenoids in nature. These chromophores are defined by a pattern of single and double bond alternation that is reversed relative to most carotenoids. Rhodoxanthin is found in the plumage of several families of birds, including fruit doves (Ptilinopus, Columbidae) and the red cotingas (Phoenicircus, Cotingidae). The coloration associated with the rhodoxanthin-containing plumage of these fruit dove and cotinga species ranges from brilliant red to magenta or purple. In the present study, rhodoxanthin is characterized in situ by UV-Vis reflectance and resonance Raman spectroscopy to gain insights into the mechanisms of color-tuning. The spectra are compared with those of the isolated pigment in solution and in thin solid films. Key vibrational signatures are identified for three isomers of rhodoxanthin, primarily in the fingerprint region. Electronic structure (DFT) calculations are employed to describe the normal modes of vibration, and determine characteristic modes of retro-carotenoids. These results are discussed in the context of various mechanisms that change the electronic absorption, including structural distortion of the chromophore or enhanced delocalization of π-electrons in the ground-state. From the spectroscopic evidence, we suggest that the shift in absorption is likely a consequence of perturbations that primarily affect the excited state of the chromophore. PMID:24055537

  5. Impurity effects in crystal growth from solutions: Steady states, transients and step bunch motion

    NASA Astrophysics Data System (ADS)

    Ranganathan, Madhav; Weeks, John D.

    2014-05-01

    We analyze a recently formulated model in which adsorbed impurities impede the motion of steps in crystals grown from solutions, while moving steps can remove or deactivate adjacent impurities. In this model, the chemical potential change of an atom on incorporation/desorption to/from a step is calculated for different step configurations and used in the dynamical simulation of step motion. The crucial difference between solution growth and vapor growth is related to the dependence of the driving force for growth of the main component on the size of the terrace in front of the step. This model has features resembling experiments in solution growth, which yields a dead zone with essentially no growth at low supersaturation and the motion of large coherent step bunches at larger supersaturation. The transient behavior shows a regime wherein steps bunch together and move coherently as the bunch size increases. The behavior at large line tension is reminiscent of the kink-poisoning mechanism of impurities observed in calcite growth. Our model unifies different impurity models and gives a picture of nonequilibrium dynamics that includes both steady states and time dependent behavior and shows similarities with models of disordered systems and the pinning/depinning transition.

  6. Inverse solution technique of steady-state responses for local nonlinear structures

    NASA Astrophysics Data System (ADS)

    Wang, Xing; Guan, Xin; Zheng, Gangtie

    2016-03-01

    An inverse solution technique with the ability of obtaining complete steady-state primary harmonic responses of local nonlinear structures in the frequency domain is proposed in the present paper. In this method, the nonlinear dynamic equations of motion is first condensed from many to only one algebraic amplitude-frequency equation of relative motion. Then this equation is transformed into a polynomial form, and with its frequency as the unknown variable, the polynomial equation is solved by tracing all the solutions of frequency with the increase of amplitude. With this solution technique, some complicated dynamic behaviors such as sharp tuning, anomalous jumps, breaks in responses and detached resonance curves could be obtained. The proposed method is demonstrated and validated through a finite element beam under force excitations and a lumped parameter model with a local nonlinear element under base excitations. The phenomenon of detached resonance curves in the frequency response and its coupling effects with multiple linear modes in the latter example are observed.

  7. Enhancing and sustaining the topical ocular delivery of fluconazole using chitosan solution and poloxamer/chitosan in situ forming gel.

    PubMed

    Gratieri, Taís; Gelfuso, Guilherme Martins; de Freitas, Osvaldo; Rocha, Eduardo Melani; Lopez, Renata F V

    2011-10-01

    Fungal keratitis is a serious disease that can lead to loss of vision. Unfortunately, current therapeutic options often result in poor bioavailability of antifungal agents due to protective mechanisms of the eye. The aim of this work was to evaluate the potential of a chitosan solution as well as an in situ gel-forming system comprised of poloxamer/chitosan as vehicles for enhanced corneal permeation and sustained release of fluconazole (FLU). For this, in vitro release and ex vivo corneal permeation experiments were carried out as a function of chitosan concentration from formulation containing the chitosan alone and combined with the thermosensitive polymer, poloxamer. Microdialysis was employed in a rabbit model to evaluate the in vivo performance of the formulations. The in vitro release studies showed the sustained release of FLU from the poloxamer/chitosan formulation. Ex vivo permeation studies across porcine cornea demonstrated that the formulations studied have a permeation-enhancing effect that is independent of chitosan concentration in the range from 0.5 to 1.5% w/w. The chitosan solutions alone showed the greatest ex vivo drug permeation; however, the poloxamer/chitosan formulation presented similar in vivo performance than the chitosan solution at 1.0%; both formulations showed sustained release and about 3.5-fold greater total amount of FLU permeated when compared to simple aqueous solutions of the drug. In conclusion, it was demonstrated that both the in situ gelling formulation evaluated and the chitosan solution are viable alternatives to enhance ocular bioavailability in the treatment of fungal keratitis.

  8. Excited States in Solution at Eom-Ccsd Level with the Polarizable Continuum Model of Solvation

    NASA Astrophysics Data System (ADS)

    Caricato, M.

    2011-06-01

    Electronic excited states are at the center of many research areas, and theoretical simulations are increasingly important. Although approximate methods based on time dependent density functional theory represent a useful tool, accurate wave function methods are still the most reliable approach. These methods, however, suffer from high computational cost that limits their range of applicability. This is particularly so when the system under study is in solution. In fact, the treatment of a large number of solvent molecules, even when modeled at a low level of theory (like molecular mechanics), is cumbersome due to the large number of conformations that needs to be considered. When the solvent is not directly involved in the process, its effect can be properly accounted for by using polarizable continuum models (PCMs) where the conformational average is implicit in the solvent dielectric constant. In this contribution, the treatment of electronic excited state energy and structure of molecules in solution at the EOM-CCSD/PCM level of theory is presented. This approach represents an effective compromise between computational cost and accurate treatment of the central part of the system while taking into account the non-negligible effect of the solvent.

  9. Spin-symmetric solution of an interacting quantum dot attached to superconducting leads: Andreev states and the 0- π transition

    NASA Astrophysics Data System (ADS)

    Janiš, Václav; Pokorný, Vladislav; Žonda, Martin

    2016-09-01

    Behavior of Andreev gap states in a quantum dot with Coulomb repulsion symmetrically attached to superconducting leads is studied via the perturbation expansion in the interaction strength. We find the exact asymptotic form of the spin-symmetric solution for the Andreev states continuously approaching the Fermi level. We thereby derive a critical interaction at which the Andreev states at zero temperature merge at the Fermi energy, being the upper bound for the 0-π transition. We show that the spin-symmetric solution becomes degenerate beyond this interaction, in the π phase, and the Andreev states do not split unless the degeneracy is lifted. We further demonstrate that the degeneracy of the spin-symmetric state extends also into the 0 phase in which the solutions with zero and non-zero frequencies of the Andreev states may coexist.

  10. Modification of granular activated carbon using low molecular weight polymer for enhanced removal of Cu(2+) from aqueous solution.

    PubMed

    Yin, C Y; Aroua, M K; Daud, W M A W

    2007-01-01

    Palm shell activated carbon was modified via surface impregnation with polyethyleneimine (PEI) to enhance removal of Cu(2+) from aqueous solution in this study. The effect of PEI modification on batch adsorption of Cu(2+) as well as the equilibrium behavior of adsorption of metal ions on activated carbon were investigated. PEI modification clearly increased the Cu(2+) adsorption capacities by 68% and 75.86% for initial solution pH of 3 and 5 respectively. The adsorption data of Cu(2+) on both virgin and PEI-modified AC for both initial solution pH of 3 and 5 fitted the Langmuir and Redlich-Peterson isotherms considerably better than the Freundlich isotherm.

  11. Bound state solution of Dirac equation for Hulthen plus trigonometric Rosen Morse non-central potential using Romanovski polynomial

    SciTech Connect

    Suparmi, A. Cari, C.; Angraini, L. M.

    2014-09-30

    The bound state solutions of Dirac equation for Hulthen and trigonometric Rosen Morse non-central potential are obtained using finite Romanovski polynomials. The approximate relativistic energy spectrum and the radial wave functions which are given in terms of Romanovski polynomials are obtained from solution of radial Dirac equation. The angular wave functions and the orbital quantum number are found from angular Dirac equation solution. In non-relativistic limit, the relativistic energy spectrum reduces into non-relativistic energy.

  12. Probabilistic modelling of chromatin code landscape reveals functional diversity of enhancer-like chromatin states

    PubMed Central

    Zhou, Jian; Troyanskaya, Olga G.

    2016-01-01

    Interpreting the functional state of chromatin from the combinatorial binding patterns of chromatin factors, that is, the chromatin codes, is crucial for decoding the epigenetic state of the cell. Here we present a systematic map of Drosophila chromatin states derived from data-driven probabilistic modelling of dependencies between chromatin factors. Our model not only recapitulates enhancer-like chromatin states as indicated by widely used enhancer marks but also divides these states into three functionally distinct groups, of which only one specific group possesses active enhancer activity. Moreover, we discover a strong association between one specific enhancer state and RNA Polymerase II pausing, linking transcription regulatory potential and chromatin organization. We also observe that with the exception of long-intron genes, chromatin state transition positions in transcriptionally active genes align with an absolute distance to their corresponding transcription start site, regardless of gene length. Using our method, we provide a resource that helps elucidate the functional and spatial organization of the chromatin code landscape. PMID:26841971

  13. Component Analysis of Multipurpose Contact Lens Solutions To Enhance Activity against Pseudomonas aeruginosa and Staphylococcus aureus.

    PubMed

    Lin, Leo; Kim, Janie; Chen, Hope; Kowalski, Regis; Nizet, Victor

    2016-07-01

    More than 125 million people wear contact lenses worldwide, and contact lens use is the single greatest risk factor for developing microbial keratitis. We tested the antibacterial activity of multipurpose contact lens solutions and their individual component preservatives against the two most common pathogens causing bacterial keratitis, Pseudomonas aeruginosa and Staphylococcus aureus The in vitro antibacterial activity of five multipurpose contact lens solutions (Opti-Free GP, Boston Simplus, Boston Advance, Menicare GP, and Lobob) was assayed by the standard broth dilution method. Synergy between the preservative components found in the top performing solutions was assayed using checkerboard and time-kill assays. The ISO 14729 criteria and the standard broth dilution method were used to define an optimized contact lens solution formulation against a clinical panel of drug-susceptible and drug-resistant P. aeruginosa and S. aureus strains. Preservatives with the biguanide function group, chlorhexidine and polyaminopropylbiguanide (PAPB), had the best antistaphylococcal activity, while EDTA was the best antipseudomonal preservative. The combination of chlorhexidine and EDTA had excellent synergy against P. aeruginosa A solution formulation containing chlorhexidine (30 ppm), PAPB (5 ppm), and EDTA (5,000 ppm) had three to seven times more antipseudomonal activity than anything available to consumers today. A multipurpose contact lens solution containing a combination of chlorhexidine, PAPB, and EDTA could help to reduce the incidence of microbial keratitis for contact lens users worldwide. PMID:27139484

  14. Aqueous solutions: state of the art in ab initio molecular dynamics.

    PubMed

    Hassanali, Ali A; Cuny, Jérôme; Verdolino, Vincenzo; Parrinello, Michele

    2014-03-13

    The simulation of liquids by ab initio molecular dynamics (AIMD) has been a subject of intense activity over the last two decades. The significant increase in computational resources as well as the development of new and efficient algorithms has elevated this method to the status of a standard quantum mechanical tool that is used by both experimentalists and theoreticians. As AIMD computes the electronic structure from first principles, it is free of ad hoc parametrizations and has thus been applied to a large variety of physical and chemical problems. In particular, AIMD has provided microscopic insight into the structural and dynamical properties of aqueous solutions which are often challenging to probe experimentally. In this review, after a brief theoretical description of the Born-Oppenheimer and Car-Parrinello molecular dynamics formalisms, we show how AIMD has enhanced our understanding of the properties of liquid water and its constituent ions: the proton and the hydroxide ion. Thereafter, a broad overview of the application of AIMD to other aqueous systems, such as solvated organic molecules and inorganic ions, is presented. We also briefly describe the latest theoretical developments made in AIMD, such as methods for enhanced sampling and the inclusion of nuclear quantum effects. PMID:24516179

  15. A strategy for selecting the pH of protein solutions to enhance crystallization.

    PubMed

    Zhang, Chen Yan; Wu, Zi Qing; Yin, Da Chuan; Zhou, Bo Ru; Guo, Yun Zhu; Lu, Hui Meng; Zhou, Ren Bin; Shang, Peng

    2013-07-01

    The pH of a solution is an important parameter in crystallization that needs to be controlled in order to ensure success. The actual pH of the crystallization droplet is determined by the combined contribution of the buffers in the screening and protein solutions, although the contribution of the latter to the pH is often ignored. In this study, the effects of the buffer and protein solution pH values on the results of screening are systematically investigated. It was found that these parameters significantly affected the results and thus the following strategy for the selection of appropriate pH values is proposed: (i) when screening with only one protein solution, the pH should be as low, as high or as divergent from the pI as possible for a basic, acidic or neutral protein, respectively, within its stable pH range; (ii) when screening with two protein solutions, the pH values should be well separated from one another; and (iii) when multiple pH values are utilized, an even distribution of pH values is the best approach to increase the success rate of crystallization.

  16. A Solution Space for a System of Null-State Partial Differential Equations: Part 1

    NASA Astrophysics Data System (ADS)

    Flores, Steven M.; Kleban, Peter

    2015-01-01

    This article is the first of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations (PDEs) in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE). In CFT, these are null-state equations and conformal Ward identities. They govern partition functions for the continuum limit of a statistical cluster or loop-gas model, such as percolation, or more generally the Potts models and O( n) models, at the statistical mechanical critical point. (SLE partition functions also satisfy these equations.) For such a lattice model in a polygon with its 2 N sides exhibiting a free/fixed side-alternating boundary condition , this partition function is proportional to the CFT correlation function where the w i are the vertices of and where is a one-leg corner operator. (Partition functions for "crossing events" in which clusters join the fixed sides of in some specified connectivity are linear combinations of such correlation functions.) When conformally mapped onto the upper half-plane, methods of CFT show that this correlation function satisfies the system of PDEs that we consider. In this first article, we use methods of analysis to prove that the dimension of this solution space is no more than C N , the Nth Catalan number. While our motivations are based in CFT, our proofs are completely rigorous. This proof is contained entirely within this article, except for the proof of Lemma 14, which constitutes the second article (Flores and Kleban, in Commun Math Phys, arXiv:1404.0035, 2014). In the third article (Flores and Kleban, in Commun Math Phys, arXiv:1303.7182, 2013), we use the results of this article to prove that the solution space of this system of PDEs has dimension C N and is spanned by solutions constructed with the CFT Coulomb gas (contour integral) formalism. In the fourth article (Flores and Kleban, in Commun Math Phys, arXiv:1405

  17. Time-resolved spectroscopy of the singlet excited state of betanin in aqueous and alcoholic solutions.

    PubMed

    Wendel, Monika; Nizinski, Stanislaw; Tuwalska, Dorota; Starzak, Karolina; Szot, Dominika; Prukala, Dorota; Sikorski, Marek; Wybraniec, Slawomir; Burdzinski, Gotard

    2015-07-21

    The photophysical properties of betanin in aqueous and alcoholic solutions were determined at room temperature using ultrafast UV-vis-NIR transient absorption spectroscopy (λexc = 535 nm). Its S1 → Sn (n > 1) absorption bands appear with maxima at about λ ∼ 450 and 1220 nm. The short betanin S1 state lifetime (6.4 ps in water) is mainly determined by the efficient S1 → S0 radiationless relaxation, probably requiring a strong change in geometry, since the S1 lifetime grows to 27 ps in the more viscous ethylene glycol. The fluorescence quantum yield is very low (Φf ∼ 0.0007 in water), therefore this deactivation path is of minor importance. Other processes, such as S1 → T1 intersystem crossing or photoproduct formation, are virtually absent, since full S0 ← S1 ground state recovery is observed within tens of picoseconds after photoexcitation. The observed fast light-to-heat conversion in the absence of triplet excited state formation supports the idea that betanin is a photoprotector in vivo.

  18. Enhancement of sub-daily positioning solutions for surface deformation monitoring at Deception volcano (South Shetland Islands, Antarctica)

    NASA Astrophysics Data System (ADS)

    Prates, G.; Berrocoso, M.; Fernández-Ros, A.; García, A.

    2013-02-01

    Deception Island is one of the most visited places in Antarctica. There are biological, geological, and archeological features that are major attractions within Port Foster, its horse shoe-shaped natural inner bay, and two scientific bases that are occupied during austral summers. Deception Island is an active volcano, however, and needs to be monitored in order to reduce risk to people on the island. Surface deformation in response to fluid pressure is one of the main volcanic activities to observe. Automated data acquisition and processing using the global navigation satellite systems allow measurements of surface deformation in near real time. Nevertheless, the positioning repeatability in sub-daily solutions is affected by geophysical influences such as ocean tidal loading, among others. Such periodic influences must be accurately modeled to achieve similar repeatability as daily solutions that average them. However, a single solution each 24 h will average out the deformation suffered during that period, and the position update waiting time can be a limitation for near real-time purposes. Throughout the last five austral summer campaigns in Deception, using simultaneous wireless communications between benchmarks, a processing strategy was developed to achieve millimeter-level half-hourly positioning solutions that have similar repeatability as those given by 24-h solutions. For these half-hourly solutions, a tidal analysis was performed to assess any mismodeling of ocean tide loading, and a discrete Kalman filter was designed and implemented to enhance the sub-daily positioning repeatability. With these solutions, the volcano-dynamic activity resulting in localized surface deformation for the last five austral summer campaigns is addressed. Although based on only three carefully located benchmarks, it is shown that Deception has been shortening and subsiding during these last 4 years. The method's accuracy in baselines up to a few hundred kilometers assures

  19. GEL-STATE NMR OF BALL-MILLED WHOLE CELL WALLS IN DMSO-d6 USING 2D SOLUTION-STATE NMR SPECTROSCOPY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant cell walls were used for obtaining 2D solution-state NMR spectra without actual solubilization or structural modification. Ball-milled whole cell walls were swelled directly in the NMR tube with DMSO-d6 where they formed a gel. There are relatively few gel-state NMR studies. Most have involved...

  20. Analysis of lasers as a solution to efficiency droop in solid-state lighting

    SciTech Connect

    Chow, Weng W.; Crawford, Mary H.

    2015-10-06

    This letter analyzes the proposal to mitigate the efficiency droop in solid-state light emitters by replacing InGaN light-emitting diodes (LEDs) with lasers. The argument in favor of this approach is that carrier-population clamping after the onset of lasing limits carrier loss to that at threshold, while stimulated emission continues to grow with injection current. A fully quantized (carriers and light) theory that is applicable to LEDs and lasers (above and below threshold) is used to obtain a quantitative evaluation. The results confirm the potential advantage of higher laser output power and efficiency above lasing threshold, while also indicating disadvantages including low efficiency prior to lasing onset, sensitivity of lasing threshold to temperature, and the effects of catastrophic laser failure. As a result, a solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.

  1. Analysis of lasers as a solution to efficiency droop in solid-state lighting

    DOE PAGES

    Chow, Weng W.; Crawford, Mary H.

    2015-10-06

    This letter analyzes the proposal to mitigate the efficiency droop in solid-state light emitters by replacing InGaN light-emitting diodes (LEDs) with lasers. The argument in favor of this approach is that carrier-population clamping after the onset of lasing limits carrier loss to that at threshold, while stimulated emission continues to grow with injection current. A fully quantized (carriers and light) theory that is applicable to LEDs and lasers (above and below threshold) is used to obtain a quantitative evaluation. The results confirm the potential advantage of higher laser output power and efficiency above lasing threshold, while also indicating disadvantages includingmore » low efficiency prior to lasing onset, sensitivity of lasing threshold to temperature, and the effects of catastrophic laser failure. As a result, a solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.« less

  2. Solution to Shape Identification of Steady-state Viscous Flow Fields to Prescribe Flow Velocity Distribution

    NASA Astrophysics Data System (ADS)

    Katamine, Eiji; Kanai, Ryoma

    2015-11-01

    This paper presents a numerical solution to shape identification problem of steady-state viscous flow fields. In this study, a shape identification problem is formulated for flow velocity distribution prescribed problem, while the total dissipated energy is constrained to less than a desired value, in the viscous flow field. The square error integral between the actual flow velocity distributions and the prescribed flow velocity distributions in the prescribed sub-domains is used as the objective functional. Shape gradient of the shape identification problem is derived theoretically using the Lagrange multiplier method, adjoint variable method, and the formulae of the material derivative. Reshaping is carried out by the traction method proposed as an approach to solving shape optimization problems. The validity of proposed method is confirmed by results of 2D numerical analysis.

  3. Photon emission via surface state at the gold/acetonitrile solution interface

    SciTech Connect

    Uosaki, Kohei; Murakoshi, Kei; Kita, Hideaki )

    1991-01-24

    The emission of light caused by an electron-transfer reaction at a gold electrode in acetonitrile solution containing one of three redox species (benzophenone, trans-stilbene, and benzonitrile) with different redox potentials was studied. The high-energy threshold of the spectrum decreases linearly as the potential of the gold electrode becomes more negative. The peak position with respect to the high-energy threshold of the spectrum varies with electrode potential and is not affected by the redox potential of the electron injection species at the same electrode potential. The emission efficiency also depends on the potential. From these results, the authors proposed that the emission is due to a charge-transfer reaction inverse photoemission (CTRIP) process that takes place via a surface state.

  4. Investigating the mechanisms of amylolysis of starch granules by solution-state NMR.

    PubMed

    Baldwin, Andrew J; Egan, Danielle L; Warren, Fredrick J; Barker, Paul D; Dobson, Christopher M; Butterworth, Peter J; Ellis, Peter R

    2015-05-11

    Starch is a prominent component of the human diet and is hydrolyzed by α-amylase post-ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual starch granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfaces of waxy rice starch granules are highly mobile and that during hydrothermal treatment, when the granules swell, the number of flexible residues on the exposed surfaces increases by a factor of 15. Moreover, we show that these flexible chains are the primary substrates for α-amylase, being cleaved in the initial stages of hydrolysis. These findings allow us to conclude that the quantity of flexible α-glucan chains protruding from the granule surface will greatly influence the rate of energy acquisition from digestion of starch.

  5. Solution of steady-state, two-dimensional conservation laws by mathematical programming

    NASA Technical Reports Server (NTRS)

    Lavery, John E.

    1991-01-01

    A truly two-dimensional algorithm is created for solving the steady-state two-dimensional conservation-law problem. An overdetermined system of algebraic equations is obtained through discretization by finite-volume formulas. These equations are perturbed nonsingularly and are solved by an efficient geometrically oriented l(1) procedure. The basic algorithm and the theory for the linear case f(u) = u are presented, and computational results for the nonlinear case f(u) = sq u are also analyzed. It is noted that the l(1) procedure captures boundary shocks as well as oblige and zigzag interior shocks in bands that are one cell wide, and the solution values are accurate up to the edge of the shock.

  6. X-ray line shapes of metals: Exact solutions of a final-state interaction model

    NASA Astrophysics Data System (ADS)

    Swarts, Coenraad A.; Dow, John D.

    2005-10-01

    By means of model calculations for an independent-electron metal, we obtain exact line shapes for the photon absorption, emission, and photoemission spectra of core states, including electronic relaxation. In all cases we find an x-ray edge anomaly. For the absorption and emission spectra this anomaly is superposed on a continuum resembling Elliott exciton theory. We display how the spectra evolve from the exciton limit to the free-electron limit as the final-state interaction strength is decreased or the Fermi energy increased. We compare the spectra obtained for different final-state interactions and find that different types of interactions produce different spectral shapes. Away from threshold the absorption and emission profiles show an enhancement of the free-electron result, as predicted by the screened-exciton theory. Our results offer potential explanations for (i) incompatibilities between threshold exponents and exponents extracted from other data, (ii) the occurrence of nearly symmetric x-ray photoemission lines, and (iii) the lack of mirror symmetry of absorption and emission edges.

  7. Limitations and Extensions of the Lock-and-Key Principle: Differences between Gas State, Solution and Solid State Structures

    PubMed Central

    Schneider, Hans-Jörg

    2015-01-01

    The lock-and-key concept is discussed with respect to necessary extensions. Formation of supramolecular complexes depends not only, and often not even primarily on an optimal geometric fit between host and guest. Induced fit and allosteric interactions have long been known as important modifications. Different binding mechanisms, the medium used and pH effects can exert a major influence on the affinity. Stereoelectronic effects due to lone pair orientation can lead to variation of binding constants by orders of magnitude. Hydrophobic interactions due to high-energy water inside cavities modify the mechanical lock-and-key picture. That optimal affinities are observed if the cavity is only partially filled by the ligand can be in conflict with the lock-and-key principle. In crystals other forces than those between host and guest often dominate, leading to differences between solid state and solution structures. This is exemplified in particular with calixarene complexes, which by X-ray analysis more often than other hosts show guest molecules outside their cavity. In view of this the particular problems with the identification of weak interactions in crystals is discussed. PMID:25815592

  8. A globally convergent algorithm for the solution of the steady-state semiconductor device equations

    NASA Astrophysics Data System (ADS)

    Korman, Can E.; Mayergoyz, Isaak D.

    1990-08-01

    An iterative method for solving the discretized steady-state semiconductor device equations is presented. This method uses Gummel's block iteration technique to decouple the nonlinear Poisson and electron-hole current continuity equations. However, the main feature of this method is that it takes advantage of the diagonal nonlinearity of the discretized equations, and solves each equation iteratively by using the nonlinear Jacobi method. Using the fact that the diagonal nonlinearities are monotonically increasing functions, it is shown that this method has two important advantages. First, it has global convergence, i.e., convergence is guaranteed for any initial guess. Second, the solution of simultaneous algebraic equations is avoided by updating the value of the electrostatic and quasi-Fermi potentials at each mesh point by means of explicit formulae. This allows the implementation of this method on computers with small random access memories, such as personal computers, and also makes it very attractive to use on parallel processor machines. Furthermore, for serial computations, this method is generalized to the faster nonlinear successive overrelaxation method which has global convergence as well. The iterative solution of the nonlinear Poisson equation is formulated with energy- and position-dependent interface traps. It is shown that the iterative method is globally convergent for arbitrary distributions of interface traps. This is an important step in analyzing hot-electron effects in metal-oxide-silicon field-effect transistors (MOSFETs). Various numerical results on two- and three-dimensional MOSFET geometries are presented as well.

  9. Non-constant steady-state solutions for Brusselator type systems

    NASA Astrophysics Data System (ADS)

    Ghergu, Marius

    2008-10-01

    We are concerned with the following stationary system: \\[ \\begin{equation*}\\begin{array}{@{}ll} -\\theta \\Delta u =\\lambda (1-(b+1)u+bu^mv)\\quad& \\mbox{in}\\ \\Omega ,\\\\ \\ms -\\Delta v= \\lambda a^2(u-u^mv) & \\mbox{in}\\ \\Omega, \\label{eqs1bd} \\end{array}\\end{equation*} \\] subject to homogeneous Neumann boundary conditions. Here \\Omega \\subset{\\mathbb R}^N (N >= 1) is a smooth and bounded domain and a, b, m, λ, θ are positive parameters. The particular case m = 2 corresponds to the steady-state Brusselator system. We establish existence and non-existence results for non-constant positive classical solutions. In particular, we provide upper and lower bounds for solutions which allows us to extend the previous works in the literature without any restriction on the dimension N >= 1. Our analysis also emphasizes the role played by the nonlinearity um. The proofs rely essentially on various types of a priori estimates.

  10. State of the Art in LP-WAN Solutions for Industrial IoT Services.

    PubMed

    Sanchez-Iborra, Ramon; Cano, Maria-Dolores

    2016-05-17

    The emergence of low-cost connected devices is enabling a new wave of sensorization services. These services can be highly leveraged in industrial applications. However, the technologies employed so far for managing this kind of system do not fully cover the strict requirements of industrial networks, especially those regarding energy efficiency. In this article a novel paradigm, called Low-Power Wide Area Networking (LP-WAN), is explored. By means of a cellular-type architecture, LP-WAN-based solutions aim at fulfilling the reliability and efficiency challenges posed by long-term industrial networks. Thus, the most prominent LP-WAN solutions are reviewed, identifying and discussing the pros and cons of each of them. The focus is also on examining the current deployment state of these platforms in Spain. Although LP-WAN systems are at early stages of development, they represent a promising alternative for boosting future industrial IIoT (Industrial Internet of Things) networks and services.

  11. State of the Art in LP-WAN Solutions for Industrial IoT Services

    PubMed Central

    Sanchez-Iborra, Ramon; Cano, Maria-Dolores

    2016-01-01

    The emergence of low-cost connected devices is enabling a new wave of sensorization services. These services can be highly leveraged in industrial applications. However, the technologies employed so far for managing this kind of system do not fully cover the strict requirements of industrial networks, especially those regarding energy efficiency. In this article a novel paradigm, called Low-Power Wide Area Networking (LP-WAN), is explored. By means of a cellular-type architecture, LP-WAN–based solutions aim at fulfilling the reliability and efficiency challenges posed by long-term industrial networks. Thus, the most prominent LP-WAN solutions are reviewed, identifying and discussing the pros and cons of each of them. The focus is also on examining the current deployment state of these platforms in Spain. Although LP-WAN systems are at early stages of development, they represent a promising alternative for boosting future industrial IIoT (Industrial Internet of Things) networks and services. PMID:27196909

  12. Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions

    PubMed Central

    Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei

    2010-01-01

    One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K+, Ca2+, Na+ and SO42− ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments. PMID:22163467

  13. Vacuum-drying of maltodextrin aqueous solutions with ethanol in a foamed state

    SciTech Connect

    Kumazawa, E. ); Ido, K. ); Toei, R.; Okazaki, M. )

    1990-01-01

    This paper reports on an aqueous maltodextrin solution in a foamed state with ethanol as a model aroma component, vacuum-dried with radiative heat. A vacuum chamber was made in which the weight and temperature of the material on a belt were measured during the drying process. While measuring the drying rate, the material temperature and the retention of aroma, the effect of the drying conditions on the aroma retention were experimentally studied. Numerical solutions were obtained during the drying process by solving simultaneously two partial differential equations regarding heat and mass transfer. The drying rate depends on the heating temperature, the belt loading, and the initial total solids. Even when heated at a temperature of 150{degrees}C for 30 minutes, the experimentally measured aroma retention is over 65 percent for initial total solids exceeding 70 percent. A satisfactory agreement between the observed and the simulated values were obtained. This analytical model would appear to be useful for setting optimum drying conditions for practical vacuum dryers.

  14. State of the Art in LP-WAN Solutions for Industrial IoT Services.

    PubMed

    Sanchez-Iborra, Ramon; Cano, Maria-Dolores

    2016-01-01

    The emergence of low-cost connected devices is enabling a new wave of sensorization services. These services can be highly leveraged in industrial applications. However, the technologies employed so far for managing this kind of system do not fully cover the strict requirements of industrial networks, especially those regarding energy efficiency. In this article a novel paradigm, called Low-Power Wide Area Networking (LP-WAN), is explored. By means of a cellular-type architecture, LP-WAN-based solutions aim at fulfilling the reliability and efficiency challenges posed by long-term industrial networks. Thus, the most prominent LP-WAN solutions are reviewed, identifying and discussing the pros and cons of each of them. The focus is also on examining the current deployment state of these platforms in Spain. Although LP-WAN systems are at early stages of development, they represent a promising alternative for boosting future industrial IIoT (Industrial Internet of Things) networks and services. PMID:27196909

  15. The Impact of Enhanced Summer Thaw, Hillslope Disturbances, and Late Season Rainfall on Solute Fluxes from High Arctic Headwater Catchments

    NASA Astrophysics Data System (ADS)

    Lafreniere, M. J.; Lamoureux, S. F.

    2011-12-01

    This study examines variations in the composition and total seasonal fluxes of dissolved solutes in several small High Arctic headwater catchments at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island, Nunavut (74°54'N, 109°35'W) over multiple snowmelt seasons (2007, 2008, 2009) with contrasting climate and permafrost active layer conditions. Climate warming in the High Arctic will affect a number processes that will alter the hydrological and biogeochemical exports from the landscape. Climate change is projected to alter precipitation regimes, resulting in increases in both winter and summer precipitation in the High Arctic, thereby altering hydrological regimes. Warming will result in thickening of the seasonal active layer, which will alter hydrological flow paths and water and solute sources. Additionally, active layer thickening and permafrost warming is also project to enhance the development of thermokarst features, including hillslope disturbances, such as active layer detachment slides and retrogressive thaw slumps. This research compares the flux of inorganic and organic solutes emanating from a group of catchments that were subject to a range hillslope disturbances, or active layer detachment slides (ALDs), at the end of summer 2007. One of the catchments, Goose, was not subject to any disturbance, while active layer slides covered between 6% and 46% of the catchment area in the disturbed catchments. It was hypothesised that solute fluxes would increase primarily with increasing extent and degree of disturbance. This however, was not observed. Rather, comparing five sites with varying degrees of disturbance in 2009 illustrates that on a specific area and specific volume of runoff basis, solute fluxes were unrelated to disturbance extent. Comparing two catchments that were monitored from 2007 (pre-disturbance) through to 2009 (2 yrs post disturbance), shows that both catchments were subject to solute flux increases, however the solute

  16. Conflicts between sandhill cranes and farmers in the western United States: evolving issues and solutions

    USGS Publications Warehouse

    Austin, Jane E.

    2012-01-01

    The main conflicts between Sandhill Cranes (Grus canadensis) and farmers in western United States occur in the Rocky Mountain region during migration and wintering periods. Most crop damage by cranes occurs in mature wheat (Triticum aestivum) and barley (Hordeum vulgare), young shoots of alfalfa (Medicago sativa) and cereal grains, chilies (Capsicum annuum), and silage corn (Zea mays). Damage is related to proximity of crop fields to roost sites and timing of crane concentrations relative to crop maturity or vulnerability. The evolution of conflicts between farmers and cranes and current solutions are described for two areas of the Rocky Mountains used by staging, migrating, or wintering cranes: Grays Lake, Idaho, and the Middle Rio Grande Valley, New Mexico. In both areas, conflicts with growing crane populations were aggravated by losses of wetlands and cropland, proximity of crops to roosts and other wetland areas, changing crop types and practices, and increasing urbanization. At Grays Lake, fall-staging cranes damaged barley fields near an important breeding refuge as well as fields 15-50 km away. In the Middle Rio Grande Valley, migrating and wintering cranes damaged young alfalfa fields, chilies, and silage corn. Solutions in both areas have been addressed through cooperative efforts among federal and state agencies, that manage wetlands and croplands to increase food availability and carrying capacity on public lands, provide hazing programs for private landowners, and strategically target crane hunting to problem areas. Sustaining the success of these programs will be challenging. Areas important to Sandhill Cranes in the western United Sates experience continued loss of habitat and food resources due to urbanization, changes in agricultural crops and practices, and water-use conflicts, which threaten the abilities of both public and private landowners to manage wetlands and croplands for cranes. Conservation of habitats and water resources are important

  17. Excited state intramolecular charge transfer reaction in nonaqueous electrolyte solutions: Temperature dependence

    NASA Astrophysics Data System (ADS)

    Pradhan, Tuhin; Gazi, Harun Al Rasid; Biswas, Ranjit

    2009-08-01

    Temperature dependence of the excited state intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) in ethyl acetate (EA), acetonitrile (ACN), and ethanol at several concentrations of lithium perchlorate (LiClO4) has been investigated by using the steady state and time resolved fluorescence spectroscopic techniques. The temperature range considered is 267-343 K. The temperature dependent spectral peak shifts and reaction driving force (-ΔGr) in electrolyte solutions of these solvents can be explained qualitatively in terms of interaction between the reactant molecule and ion-atmosphere. Time resolved studies indicate that the decay kinetics of P4C is biexponential, regardless of solvents, LiClO4 concentrations, and temperatures considered. Except at higher electrolyte concentrations in EA, reaction rates in solutions follow the Arrhenius-type temperature dependence where the estimated activation energy exhibits substantial electrolyte concentration dependence. The average of the experimentally measured activation energies in these three neat solvents is found to be in very good agreement with the predicted value based on data in room temperature solvents. While the rate constant in EA shows a electrolyte concentration induced parabolic dependence on reaction driving force (-ΔGr), the former in ethanol and ACN increases only linearly with the increase in driving force (-ΔGr). The data presented here also indicate that the step-wise increase in solvent reorganization energy via sequential addition of electrolyte induces the ICT reaction in weakly polar solvents to crossover from the Marcus inverted region to the normal region.

  18. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA.

  19. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    PubMed

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA. PMID:26469934

  20. A comparison of water solubility enhancements of organic solutes by aquatic humic materials and commercial humic acids

    USGS Publications Warehouse

    Chlou, C.T.; Kile, D.E.; Brinton, T.I.; Malcolm, R.L.; Leenheer, J.A.; MacCarthy, P.

    1987-01-01

    Water solubility enhancements of 1,1-bis(p-chloro-phenyl)-2,2,2-trichloroethane (p,p???-DDT), 2,4,5,2???,5???-pentachlorobiphenyl (2,4,5,2???,5???-PCB), and 2,4,4???-tri-chlorobiphenyl (2,4,4???-PCB) by dissolved organic matter have been studied with the following samples: (1) acidic water samples from the Suwannee River, Georgia, and the Sopchoppy River, Florida; (2) a humic extract of a nearly neutral pH water from the Calcasieu River, Louisiana; (3) commercial humic acids from the Aldrich Chemical Co. and Fluka-Tridom Chemical Corp. The calculated partition coefficients on a dissolved organic carbon basis (Kdoc) for organic solutes with water samples and aquatic humic extracts from this and earlier studies indicate that the enhancement effect varies with the molecular composition of the aquatic humic materials. The Kdoc values with water and aquatic humic samples are, however, far less than the observed Kdoc values obtained with the two commercial samples, by factors of about 4-20. In view of this finding, one should be cautious in interpreting the effects of the dissolved organic matter on solubility enhancement of organic solutes on the basis of the use of commercial humic acids.

  1. Enhancement of electric field-mediated gene delivery through pretreatment of tumors with a hyperosmotic mannitol solution.

    PubMed

    Henshaw, J; Mossop, B; Yuan, F

    2011-01-01

    Pulsed electric fields can enhance interstitial transport of plasmid DNA (pDNA) in solid tumors. However, the extent of enhancement is still limited. To this end, the effects of cellular resistance to electric field-mediated gene delivery were investigated. The investigation used two tumor cell lines (4T1 (a murine mammary carcinoma) and B16.F10 (a metastatic subline of B16 murine melanoma)) either in suspensions or implanted in two in vivo models (dorsal skin-fold chamber (DSC) and hind leg). The volume fraction of cells was altered by pretreatment with a hyperosmotic mannitol solution (1 M). It was observed that the pretreatment reduced the volumes of 4T1 and B16.F10 cells, suspended in an agarose gel, by 50 and 46%, respectively, over a 20-min period, but did not cause significant changes ex vivo in volumes of hind-leg tumor tissues grown from the same cells in mice. The mannitol pretreatment in vivo improved electric field-mediated gene delivery in the hind-leg tumor models, in terms of reporter gene expression, but resulted in minimal enhancement in pDNA electrophoresis over a few microns distance in the DSC tumor models. These data demonstrated that hyperosmotic mannitol solution could effectively improve electric field-mediated gene delivery around individual cells in vivo by increasing the extracellular space. PMID:20847751

  2. Solution and Solid-State Studies of DNA-Programmable Nanoparticle Single Crystals

    NASA Astrophysics Data System (ADS)

    Auyeung, Evelyn

    This thesis lays the foundation for three main areas that have significantly advanced the field of DNA-programmable nanoparticle assembly: (1) the synthesis of nanoparticle superlattices with novel lattice symmetries (2) post-assembly characterization and applications of superlattices that have been transferred from solution to the solid state and (3) the realization of a slow-cooling strategy for synthesizing faceted nanoparticle single crystals. Together, these advances mark a turning point in the evolution of DNA-programmable assembly from a simple proof-of-concept demonstrated in 1996 to a powerful materials development strategy that has inspired many ongoing investigations in fields including catalysis, plasmonics, and electronics. Chapter 1 begins with an overview of controlled crystallization and its importance across fields including chemistry and materials science. This followed by a description of DNA-programmable assembly and a discussion on its advantages as an assembly strategy. Chapter 2 describes a powerful strategy for synthesizing nanoparticle superlattices using a coreless nanoparticle consisting purely of spherically-oriented oligonucleotides. This "three dimensional spacer approach" allows for the synthesis of nanoparticle superlattices with exotic structures, including one with no mineral equivalent. While DNA is a versatile ligand for nanoparticle assembly, the resulting superlattices are only stable in solution. Chapter 3 addresses these limitations and presents a method for transitioning these materials from solution to the solid state through silica encapsulation. This encapsulation process has transformed the ability to interrogate these materials using electron microscopy, and it has enabled all the studies in subsequent chapters of this thesis. In Chapter 4, a slow-cooling crystallization technique is described that allows for the synthesis of single crystalline microcrystals with well-defined facets from DNA-nanoparticle building blocks

  3. A Solution Space for a System of Null-State Partial Differential Equations: Part 4

    NASA Astrophysics Data System (ADS)

    Flores, Steven M.; Kleban, Peter

    2015-01-01

    This article is the last of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE). The system comprises 2 N null-state equations and three conformal Ward identities that govern CFT correlation functions of 2 N one-leg boundary operators. In the first two articles (Flores and Kleban in Commun Math Phys, 2012; Flores and Kleban, in Commun Math Phys, 2014), we use methods of analysis and linear algebra to prove that dim , with C N the Nth Catalan number. Using these results in the third article (Flores and Kleban, in Commun Math Phys, 2013), we prove that dim and is spanned by (real-valued) solutions constructed with the Coulomb gas (contour integral) formalism of CFT. In this article, we use these results to prove some facts concerning the solution space . First, we show that each of its elements equals a sum of at most two distinct Frobenius series in powers of the difference between two adjacent points (unless is odd, in which case a logarithmic term may appear). This establishes an important element in the operator product expansion for one-leg boundary operators, assumed in CFT. We also identify particular elements of , which we call connectivity weights, and exploit their special properties to conjecture a formula for the probability that the curves of a multiple-SLE process join in a particular connectivity. This leads to new formulas for crossing probabilities of critical lattice models inside polygons with a free/fixed side-alternating boundary condition, which we derive in Flores et al. (Partition functions and crossing probabilities for critical systems inside polygons, in preparation). Finally, we propose a reason for why the exceptional speeds [certain values that appeared in the analysis of the Coulomb gas solutions in Flores and Kleban (Commun Math Phys, 2013)] and

  4. STATE-SPACE SOLUTIONS TO THE DYNAMIC MAGNETOENCEPHALOGRAPHY INVERSE PROBLEM USING HIGH PERFORMANCE COMPUTING

    PubMed Central

    Long, Christopher J.; Purdon, Patrick L.; Temereanca, Simona; Desai, Neil U.; Hämäläinen, Matti S.; Brown, Emery N.

    2011-01-01

    Determining the magnitude and location of neural sources within the brain that are responsible for generating magnetoencephalography (MEG) signals measured on the surface of the head is a challenging problem in functional neuroimaging. The number of potential sources within the brain exceeds by an order of magnitude the number of recording sites. As a consequence, the estimates for the magnitude and location of the neural sources will be ill-conditioned because of the underdetermined nature of the problem. One well-known technique designed to address this imbalance is the minimum norm estimator (MNE). This approach imposes an L2 regularization constraint that serves to stabilize and condition the source parameter estimates. However, these classes of regularizer are static in time and do not consider the temporal constraints inherent to the biophysics of the MEG experiment. In this paper we propose a dynamic state-space model that accounts for both spatial and temporal correlations within and across candidate intra-cortical sources. In our model, the observation model is derived from the steady-state solution to Maxwell's equations while the latent model representing neural dynamics is given by a random walk process. We show that the Kalman filter (KF) and the Kalman smoother [also known as the fixed-interval smoother (FIS)] may be used to solve the ensuing high-dimensional state-estimation problem. Using a well-known relationship between Bayesian estimation and Kalman filtering, we show that the MNE estimates carry a significant zero bias. Calculating these high-dimensional state estimates is a computationally challenging task that requires High Performance Computing (HPC) resources. To this end, we employ the NSF Teragrid Supercomputing Network to compute the source estimates. We demonstrate improvement in performance of the state-space algorithm relative to MNE in analyses of simulated and actual somatosensory MEG experiments. Our findings establish the benefits

  5. Reasons why current speech-enhancement algorithms do not improve speech intelligibility and suggested solutions

    PubMed Central

    Loizou, Philipos C.; Kim, Gibak

    2011-01-01

    Existing speech enhancement algorithms can improve speech quality but not speech intelligibility, and the reasons for that are unclear. In the present paper, we present a theoretical framework that can be used to analyze potential factors that can influence the intelligibility of processed speech. More specifically, this framework focuses on the fine-grain analysis of the distortions introduced by speech enhancement algorithms. It is hypothesized that if these distortions are properly controlled, then large gains in intelligibility can be achieved. To test this hypothesis, intelligibility tests are conducted with human listeners in which we present processed speech with controlled speech distortions. The aim of these tests is to assess the perceptual effect of the various distortions that can be introduced by speech enhancement algorithms on speech intelligibility. Results with three different enhancement algorithms indicated that certain distortions are more detrimental to speech intelligibility degradation than others. When these distortions were properly controlled, however, large gains in intelligibility were obtained by human listeners, even by spectral-subtractive algorithms which are known to degrade speech quality and intelligibility. PMID:21909285

  6. An exact solution for the steady state phase distribution in an array of oscillators coupled on a hexagonal lattice

    NASA Technical Reports Server (NTRS)

    Pogorzelski, Ronald J.

    2004-01-01

    When electronic oscillators are coupled to nearest neighbors to form an array on a hexagonal lattice, the planar phase distributions desired for excitation of a phased array antenna are not steady state solutions of the governing non-linear equations describing the system. Thus the steady state phase distribution deviates from planar. It is shown to be possible to obtain an exact solution for the steady state phase distribution and thus determine the deviation from the desired planar distribution as a function of beam steering angle.

  7. c-Abl Tyrosine Kinase Adopts Multiple Active Conformational States in Solution.

    PubMed

    Badger, John; Grover, Prerna; Shi, Haibin; Panjarian, Shoghag B; Engen, John R; Smithgall, Thomas E; Makowski, Lee

    2016-06-14

    Protein tyrosine kinases of the Abl family have diverse roles in normal cellular regulation and drive several forms of leukemia as oncogenic fusion proteins. In the crystal structure of the inactive c-Abl kinase core, the SH2 and SH3 domains dock onto the back of the kinase domain, resulting in a compact, assembled state. This inactive conformation is stabilized by the interaction of the myristoylated N-cap with a pocket in the C-lobe of the kinase domain. Mutations that perturb these intramolecular interactions result in kinase activation. Here, we present X-ray scattering solution structures of multidomain c-Abl kinase core proteins modeling diverse active states. Surprisingly, the relative positions of the regulatory N-cap, SH3, and SH2 domains in an active myristic acid binding pocket mutant (A356N) were virtually identical to those of the assembled wild-type kinase core, indicating that Abl kinase activation does not require dramatic reorganization of the downregulated core structure. In contrast, the positions of the SH2 and SH3 domains in a clinically relevant imatinib-resistant gatekeeper mutant (T315I) appear to be reconfigured relative to their positions in the wild-type protein. Our results demonstrate that c-Abl kinase activation can occur either with (T315I) or without (A356N) global allosteric changes in the core, revealing the potential for previously unrecognized signaling diversity. PMID:27166638

  8. Molecular dynamics of excited state intramolecular proton transfer: 3-hydroxyflavone in solution

    SciTech Connect

    Bellucci, Michael A.; Coker, David F.

    2012-05-21

    The ultrafast enol-keto photoisomerization in the lowest singlet excited state of 3-hydroxyflavone is investigated using classical molecular dynamics in conjunction with empirical valence bond (EVB) potentials for the description of intramolecular interactions, and a molecular mechanics and variable partial charge model, dependent on transferring proton position, for the description of solute-solvent interactions. A parallel multi-level genetic program was used to accurately fit the EVB potential energy surfaces to high level ab initio data. We have studied the excited state intramolecular proton transfer (ESIPT) reaction in three different solvent environments: methylcyclohexane, acetonitrile, and methanol. The effects of the environment on the proton transfer time and the underlying mechanisms responsible for the varied time scales of the ESIPT reaction rates are analyzed. We find that simulations with our EVB potential energy surfaces accurately reproduce experimentally determined reaction rates, fluorescence spectra, and vibrational frequency spectra in all three solvents. Furthermore, we find that the ultrafast ESIPT process results from a combination of ballistic transfer, and intramolecular vibrational redistribution, which leads to the excitation of a set of low frequency promoting vibrational modes. From this set of promoting modes, we find that an O-O in plane bend and a C-H out of plane bend are present in all three solvents, indicating that they are fundamental to the ultrafast proton transfer. Analysis of the slow proton transfer trajectories reveals a solvent mediated proton transfer mechanism, which is diffusion limited.

  9. Supramolecular stabilization of metastable tautomers in solution and the solid state.

    PubMed

    Juribašić, Marina; Bregović, Nikola; Stilinović, Vladimir; Tomišić, Vladislav; Cindrić, Marina; Sket, Primož; Plavec, Janez; Rubčić, Mirta; Užarević, Krunoslav

    2014-12-22

    This work presents a successful application of a recently reported supramolecular strategy for stabilization of metastable tautomers in cocrystals to monocomponent, non-heterocyclic, tautomeric solids. Quantum-chemical computations and solution studies show that the investigated Schiff base molecule, derived from 3-methoxysalicylaldehyde and 2-amino-3-hydroxypyridine (ap), is far more stable as the enol tautomer. In the solid state, however, in all three obtained polymorphic forms it exists solely as the keto tautomer, in each case stabilized by an unexpected hydrogen-bonding pattern. Computations have shown that hydrogen bonding of the investigated Schiff base with suitable molecules shifts the tautomeric equilibrium to the less stable keto form. The extremes to which supramolecular stabilization can lead are demonstrated by the two polymorphs of molecular complexes of the Schiff base with ap. The molecules of both constituents of molecular complexes are present as metastable tautomers (keto anion and protonated pyridine, respectively), which stabilize each other through a very strong hydrogen bond. All the obtained solid forms proved stable in various solid-state and solvent-mediated methods used to establish their relative thermodynamic stabilities and possible interconversion conditions.

  10. c-Abl Tyrosine Kinase Adopts Multiple Active Conformational States in Solution

    PubMed Central

    2016-01-01

    Protein tyrosine kinases of the Abl family have diverse roles in normal cellular regulation and drive several forms of leukemia as oncogenic fusion proteins. In the crystal structure of the inactive c-Abl kinase core, the SH2 and SH3 domains dock onto the back of the kinase domain, resulting in a compact, assembled state. This inactive conformation is stabilized by the interaction of the myristoylated N-cap with a pocket in the C-lobe of the kinase domain. Mutations that perturb these intramolecular interactions result in kinase activation. Here, we present X-ray scattering solution structures of multidomain c-Abl kinase core proteins modeling diverse active states. Surprisingly, the relative positions of the regulatory N-cap, SH3, and SH2 domains in an active myristic acid binding pocket mutant (A356N) were virtually identical to those of the assembled wild-type kinase core, indicating that Abl kinase activation does not require dramatic reorganization of the downregulated core structure. In contrast, the positions of the SH2 and SH3 domains in a clinically relevant imatinib-resistant gatekeeper mutant (T315I) appear to be reconfigured relative to their positions in the wild-type protein. Our results demonstrate that c-Abl kinase activation can occur either with (T315I) or without (A356N) global allosteric changes in the core, revealing the potential for previously unrecognized signaling diversity. PMID:27166638

  11. Solution-based characterization of surface-enhanced Raman response of single scattering centers

    SciTech Connect

    Laurence, T A; Talley, C; Schwartzberg, A; Braun, G; Moskovits, M; Reich, N; Huser, T

    2008-03-06

    We demonstrate the rapid optical characterization of large numbers of individual metal nanoparticles freely diffusing in colloidal solution by confocal laser spectroscopy. We find that hollow gold nanospheres and solid silver nanoparticles linked with a bifunctional ligand, both designed nanostructures, exhibit significantly higher monodispersity in their Rayleigh and Raman scattering response than randomly aggregated gold and silver nanoparticles. We show that measurements of rotational diffusion timescales allow sizing of particles significantly more reliably than can be obtained using translational diffusion timescales.

  12. Perfusion enhances solute transfer into the shell of hollow fiber membrane bioreactors for bone tissue engineering.

    PubMed

    De Napoli, Ilaria Ester; Catapano, Gerardo

    2010-06-01

    Preparation of tissue engineered (TE) 3D constructs to repair large bone defects is limited by the difficult supply of nutrients and oxygen to cells in the innermost regions of constructs cultured in bioreactors. Poor oxygenation negatively affects cell viability and function. Bioreactor design optimization may help relieve these limitations. Bioreactors in which cells are cultured outside bundles of hollow fiber membranes (HFMBs) are structurally similar to natural bone. HFMB operation in pure diffusion has been reported to suffice for fibroblasts, but is deemed insufficient for bone cells. In this paper, the effect of perfusion flows in the cell compartment on solute transfer was investigated in HFMBs differing in design and operating conditions. HFMBs were designed and operated using values of non-dimensional groups that ensured solutes transfer towards the cell compartment mainly by diffusion; in the presence of low to high Starling flows; in the presence of pulsatile radial flows obtained by periodically stopping the solution flow leaving the bioreactor using a pinch valve. Distribution of matter in cell-free HFMBs was evaluated with tracer experiments in an optimized apparatus. Effectiveness of solute transfer to cell compartment was assessed based on the bioreactor response in terms of the shell volume actively involved in mass transfer (V(MTA)) according to transport models developed specifically for the purpose. V(MTA) increased with increasing Starling flows. In the pulsatile radial flow mode, tracer concentration in the shell increased 3 times faster than at high Starling flows. This suggests that controlled perfusion flows in HFMBs might enable the engineering of large TE bone constructs. PMID:20669143

  13. YbCu2Si2-LaCu2Si2 Solid Solutions with Enhanced Thermoelectric Power Factors

    NASA Astrophysics Data System (ADS)

    Lehr, Gloria J.; Morelli, Donald T.; Jin, Hyungyu; Heremans, Joseph P.

    2015-06-01

    Cryogenic Peltier coolers are ideal for cooling infrared sensors on satellites. To make these thermoelectric devices a realistic option for this application, the efficiency of thermoelectric materials at cryogenic temperatures must be substantially enhanced. Intermediate valence Yb-based compounds have large peaks in the Seebeck coefficient at low temperatures; to optimize these materials this must be understood. We created solid solutions between the intermediate valence compound YbCu2Si2 and an isostructural compound LaCu2Si2 to manipulate the temperature at which the Seebeck coefficient peaks and to maximize zT by reduction of lattice thermal conductivity. An enormous power factor of 110 μW/cm K2 at 100 K and a maximum zT of 0.14 at 125 K were achieved for one of these solid solutions.

  14. Improving microalgal growth with reduced diameters of aeration bubbles and enhanced mass transfer of solution in an oscillating flow field.

    PubMed

    Yang, Zongbo; Cheng, Jun; Lin, Richen; Zhou, Junhu; Cen, Kefa

    2016-07-01

    A novel oscillating gas aerator combined with an oscillating baffle was proposed to generate smaller aeration bubbles and enhance solution mass transfer, which can improve microalgal growth in a raceway pond. A high-speed photography system (HSP) was used to measure bubble diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure mass-transfer coefficient and mixing time. Bubble diameter and generation time decreased with decreased aeration gas rate, decreased orifice diameter, and increased water velocity in the oscillating gas aerator. The optimized oscillating gas aerator decreased bubble diameter and generation time by 25% and 58%, respectively, compared with a horizontal tubular gas aerator. Using an oscillating gas aerator and an oscillating baffle in a raceway pond increased the solution mass-transfer coefficient by 15% and decreased mixing time by 32%; consequently, microalgal biomass yield increased by 19%. PMID:27035474

  15. Improving microalgal growth with reduced diameters of aeration bubbles and enhanced mass transfer of solution in an oscillating flow field.

    PubMed

    Yang, Zongbo; Cheng, Jun; Lin, Richen; Zhou, Junhu; Cen, Kefa

    2016-07-01

    A novel oscillating gas aerator combined with an oscillating baffle was proposed to generate smaller aeration bubbles and enhance solution mass transfer, which can improve microalgal growth in a raceway pond. A high-speed photography system (HSP) was used to measure bubble diameter and generation time, and online precise dissolved oxygen probes and pH probes were used to measure mass-transfer coefficient and mixing time. Bubble diameter and generation time decreased with decreased aeration gas rate, decreased orifice diameter, and increased water velocity in the oscillating gas aerator. The optimized oscillating gas aerator decreased bubble diameter and generation time by 25% and 58%, respectively, compared with a horizontal tubular gas aerator. Using an oscillating gas aerator and an oscillating baffle in a raceway pond increased the solution mass-transfer coefficient by 15% and decreased mixing time by 32%; consequently, microalgal biomass yield increased by 19%.

  16. Enhanced two-photon absorption and fluorescence upconversion in Thioflavin T micelle-type aggregates in glycerol/water solution

    NASA Astrophysics Data System (ADS)

    Donnelly, Julie; Vesga, Yuly; Hernandez, Florencio E.

    2016-09-01

    In this article, we report the systematic characterization of the two-photon absorption of ThT in different mixtures of glycerol/water solution. The relationships of TPA peak position and amplitude revealed a dependence on particle size suggesting that the curious trend observed in TPA with changing glycerol content can be attributed to the presence of micelle-type aggregates. Consequently, the relatively strong TPA cross-section (δTPA = 300 GM) obtained in 8.75% glycerol/water solutions could be attributed to the immobilization of dye molecules and the strong coupling of the molecular transition dipoles in micelle-type aggregates. This enhancement of TPA, in addition to the already reported significant fluorescence quantum yield of ThT attached to brain tissue, is expected to boost the application of this compound for in vitro and perhaps in vivo high resolution multiphoton bioimaging of amyloids in brain tissue.

  17. Accelerometer based solution for precision livestock farming: geolocation enhancement and animal activity identification

    NASA Astrophysics Data System (ADS)

    Terrasson, G.; Llaria, A.; Marra, A.; Voaden, S.

    2016-07-01

    The rapid evolution of electronics and communication technologies in the last years has contributed to the expansion of Precision Livestock Farming applications. In this context, animal geolocation systems applied to extensive farming are interesting for farmers to optimize their daily work organization. Nevertheless, the deployment of these solutions implies several technical challenges which must be resolved, mainly the energy consumption and the suitability of the communication protocols. A recently developed solution that deals with these technical challenges is the e-Pasto platform, which is composed of low power geolocation devices embedded into collars that offer an energetic autonomy of at least seven months, completed with a visualization user interface. The autonomy is assured employing a duty-cycle operation that results in one geolocation position measurement per hour. This work studies the employ of accelerometers to overcome this limitation assuring, at the same time, the required autonomy for the geolocation device. The authors also propose an algorithm that processes the acceleration data in order to identify the steps of an individual. The whole solution (step identification and geolocation) has been validated by means of several experimental tests.

  18. Enhanced capacity of chitosan for transition-metal ions in sulphate-sulphuric acid solutions.

    PubMed

    Muzzarelli, R A; Rocchetti, R

    1974-11-01

    Batch measurements have shown that the collection yields of chitosan for chromium(III), iron(III), nickel, copper(II), zinc and mercury(II) from sulphuric acid solutions are higher when the solutions contain ammonium sulphate, or when chitosan conditioned in ammonium sulphate is used, particularly at pH 3.0 and 5.0. The contrary is verified for the oxy-anions vanadate, chromate and molybdate. Manganese is never collected. At pH 1.0 no collection occurs. A procedure for recycling chromatographic columns includes fixation of Cu or Ni from a sulphate solution at pH 3-5 on sulphate-conditioned chitosan, and elution with 0.1M sulphuric acid/0.1M ammonium sulphate at pH 1.0; the presence of sulphate in the eluent obviates the detrimental effect of sulphuric acid on the next cycle. Sulphate is the favoured counter-ion of the chelated cations and its action produces shorter chromatographic bands. The interaction of sulphate with chitosan is discussed in terms of crystallinity and steric distribution of the protonated amino-groups in the polymer. Data on the new diethylaminohydroxypropylcellulose are included. PMID:18961577

  19. Efficiency enhancement in solution-processed organic small molecule: Fullerene solar cells via solvent vapor annealing

    NASA Astrophysics Data System (ADS)

    Miao, Jingsheng; Chen, Hui; Liu, Feng; Zhao, Baofeng; Hu, Lingyu; He, Zhicai; Wu, Hongbin

    2015-05-01

    We report highly efficient small molecule solar cells (SMSCs) by using dichloromethane solvent vapor annealing method. The resulted devices delivered a power conversion efficiency (PCE) of 8.3%, which is among the highest in SMSCs. Comparing to the control devices, the short circuit current (Jsc), fill factor, and PCE of solvent vapor annealed devices are significantly improved. Summarizing the results of optical absorption, film morphology, and charge carrier transporting properties, we see that the enhanced structure order and reduced size of phase separation are major reasons for the improved device performances, establishing a solid structure-property relationship. The solvent vapor annealing method can thus be a useful method in device fabrication to enhance performances of SMSCs.

  20. Inclusion of Paracetamol into β-cyclodextrin nanocavities in solution and in the solid state

    NASA Astrophysics Data System (ADS)

    El-Kemary, Maged; Sobhy, Saffaa; El-Daly, Samy; Abdel-Shafi, Ayman

    2011-09-01

    We report on steady-state UV-visible absorption and emission characteristics of Paracetamol, drug used as antipyretic agent, in water and within cyclodextrins (CDs): β-CD, 2-hydroxypropyl- β-CD (HP- β-CD) and 2,6-dimethyl- β-CD (Me- β-CD). The results reveal that Paracetamol forms a 1:1 inclusion complex with CD. Upon encapsulation, the emission intensity enhances, indicating a confinement effect of the nanocages on the photophysical behavior of the drug. Due to its methyl groups, the Me- β-CD shows the largest effect for the drug. The observed binding constant showing the following trend: Me- β-CD > HP- β-CD > β-CD. The less complexing effectiveness of HP- β-CD is due to the steric effect of the hydroxypropyl-substituents, which can hamper the inclusion of the guest molecules. The solid state inclusion complex was prepared by co-precipitation method and its characterization was investigated by Fourier transform infrared spectroscopy, 1H NMR and X-ray diffractometry. These approaches indicated that Paracetamol was able to form an inclusion complex with CDs, and the inclusion compounds exhibited different spectroscopic features and properties from Paracetamol.

  1. Defining the solution-state dimer structure of Escherichia coli SecA using Förster resonance energy transfer†

    PubMed Central

    Auclair, Sarah M.; Oliver, Donald B.; Mukerji, Ishita

    2013-01-01

    The Sec machinery constitutes the major pathway for protein translocation in bacteria. SecA is thought to act as a molecular motor driving preprotein translocation across the membrane by repeated ATP-driven cycles of insertion and retraction at the translocon channel. SecA is predominately a dimer under physiological conditions; however, its oligomeric state during active protein translocation is still unresolved. Five SecA crystal structures have been determined, each displaying a different dimer interface, suggesting that SecA may adopt different dimer configurations. In this study, a Förster resonance energy transfer (FRET) approach was utilized with nine functional monocysteine SecA mutants labeled with appropriate dyes to determine the predominant solution state dimer. Three different dye pairs allowed interprotomer distances ranging from 20-140 Å to be investigated. Comparison of 15 experimentally determined distances with those predicted from X-ray structures showed the greatest agreement with the B. subtilis SecA anti-parallel dimer structure (Hunt, J., Weinkauf, S., Henry, L., Fak, J.J., McNicholas, P., Oliver, D.B., and Deisenhfer, J. (2002) Science 297, 2018-2026). The binding of two signal peptides to SecA was also examined to determine their effect on SecA dimer structure. We found that the SecA dimer is maintained upon peptide binding; however, the preprotein cross-linking domain (PPXD) and helical wing domain (HWD) regions experience significant conformational changes, and the PPXD movement is greatly enhanced by binding of an extended signal peptide containing an additional 19 residues. Modeling of an ‘open’ antiparallel dimer structure suggests that binding of preprotein to SecA induces an activated open conformation suitable for binding to SecYEG. PMID:23484952

  2. Toxicity of hemoglobin solutions: hemoglobin is a lipopolysaccharide (LPS) binding protein which enhances LPS biological activity.

    PubMed

    Roth, R I; Kaca, W

    1994-01-01

    Administration of alpha alpha-crosslinked stroma-free hemoglobin (SFH) as a cell-free resuscitation fluid is associated with multiple organ toxicities. Many of these toxicities are characteristic of the pathophysiological effects of bacterial endotoxins (lipopolysaccharide, LPS). To better understand the potential role of LPS in the observed in vivo toxicities of SFH, we examined mixtures of SFH and E. coli LPS for evidence of LPS-SFH complex formation. LPS-SFH complexes were demonstrated by three techniques: ultrafiltration through 300 kDa cut-off membranes, which distinguished LPS in complexes (87-89% < 300 kDa) from LPS alone (90% > 300 kDa); density centrifugation through 5% sucrose, which distinguished denser LPS alone from LPS-SFH complexes; and precipitation by 67% ethanol, which demonstrated 2-3 fold increased precipitability of complexes compared to SFH alone. Interaction of LPS with SFH was also associated with markedly increased biological activity of LPS, as manifested by enhancement of LPS activation of Limulus amebocyte lysate (LAL), increased release of human mononuclear cell tissue factor, and enhanced production of cultured human endothelial cell tissue factor. These results demonstrated that hemoglobin can serve as an endotoxin binding protein, and that this interaction results in the alteration of several LPS physical characteristics and enhancement of LPS biological activities.

  3. Pool boiling of enhanced heat transfer surfaces in refrigerant-oil mixtures and aqueous calcium sulfate solutions

    SciTech Connect

    Curcio, L.A.; Somerscales, E.F.

    1994-08-01

    Pool boiling data of structured surfaces in R113/3GS oil mixtures show a general decrease in heat transfer with oil concentration, degradation in performance of all surfaces at 10% oil, no change in enhancement of the structured surfaces over plain surface, and restoration of performance of the enhanced surfaces upon cleaning in denatured alcohol. Fouling data of structured surfaces in pool boiling of sat. aq. CaSO{sub 4} solution show that effects of fouling (wall superheat changes, deposit weight) are more pronounced at 80 kW/m{sup 2} than at 10 kW/m{sup 2} heat flux; precipitation fouling show an effect within the first 2 h exposure. High flux surfaces have lower deposition weight than other surfaces; thus the deposition rate may depend strongly on wall superheat. The numerous nucleation sites of the enhanced surfaces provide more turbulent motion near the boiling surface than for the plain surface; thus the removal rate should be greater for an enhanced surface, although no removal of a deposit was ever observed.

  4. Use of a Measure of Reading Comprehension to Enhance Prediction on the State High Stakes Assessment

    ERIC Educational Resources Information Center

    Shapiro, Edward S.; Solari, Emily; Petscher, Yaacov

    2008-01-01

    The current study examined the diagnostic accuracy of two screening measures of risk for future difficulties in reading comprehension, as well as the degree to which adding a screening measure of reading comprehension enhanced the prediction of Oral Reading Fluency to outcomes of student reading performance on the state high stakes assessment for…

  5. Excited state polarizabilities in solution obtained by cubic response theory: Calculations on para-, ortho-, and meta-nitroaniline

    NASA Astrophysics Data System (ADS)

    Jonsson, Dan; Norman, Patrick; Ågren, Hans; Luo, Yi; Sylvester-Hvid, Kristian O.; Mikkelsen, Kurt V.

    1998-10-01

    We show that response theory implemented with a self-consistent reaction field theory model is a viable approach to simulate excited state polarizabilities of molecules in solution. The excited state polarizabilities are in this approach given by the double residue of the ground state cubic response functions, accounting for both equilibrium and nonequilibrium contributions to the interaction with the outer medium. The effects of the inertial polarization of the solvent on the polarizabilities of the solutes are shown to strongly depend on the solvent configuration, whether the solvent is in equilibrium or in nonequilibrium with the charge distribution of the investigated compound. The inertial polarization vector in the nonequilibrium solvent configuration represents the equilibrated solvent configuration when solvating the ground state of the solute. This inertial polarization vector is not in equilibrium with any of the excited states and therefore one observes a rather different behavior between nonequilibrium and equilibrium solvent descriptions of the solute. Illustrative calculations are presented for para-, meta-, and ortho-nitroanilines in gas and solution phases. Results have been compared with experimental data where available.

  6. Multimerization of solution-state proteins by tetrakis(4-sulfonatophenyl)porphyrin.

    PubMed

    Kokhan, Oleksandr; Ponomarenko, Nina; Pokkuluri, P Raj; Schiffer, Marianne; Tiede, David M

    2014-08-12

    Surface binding and interactions of anionic porphyins bound to cationic proteins have been studied for nearly three decades and are relevant as models for protein surface molecular recognition and photoinitiated electron transfer. However, interpretation of data in nearly all reports explicitly or implicitly assumed interaction of porphyrin with monodisperse proteins in solutions. In this report, using small-angle X-ray scattering with solution phase samples, we demonstrate that horse heart cytochrome (cyt) c, triheme cytochrome c7 PpcA from Geobacter sulfurreducens, and hen egg lysozyme multimerize in the presence of zinc tetrakis(4-sulfonatophenyl)porphyrin (ZnTPPS). Multimerization of cyt c showed a pH dependence with a stronger apparent binding affinity under alkaline conditions and was weakened in the presence of a high salt concentration. Ferric-cyt c formed complexes larger than those formed by ferro-cyt c. Free base TPPS and FeTPPS facilitated formation of complexes larger than those of ZnTPPS. No increase in protein aggregation state for cationic proteins was observed in the presence of cationic porphyrins. All-atom molecular dynamics simulations of cyt c and PpcA with free base TPPS corroborated X-ray scattering results and revealed a mechanism by which the tetrasubstituted charged porphyrins serve as bridging ligands nucleating multimerization of the complementarily charged protein. The final aggregation products suggest that multimerization involves a combination of electrostatic and hydrophobic interactions. The results demonstrate an overlooked complexity in the design of multifunctional ligands for protein surface recognition. PMID:25028772

  7. Branched truxene and triindole compounds and their solid-state luminescent enhancement

    NASA Astrophysics Data System (ADS)

    Du, Xianchao; Yuan, Mao-Sen; Xu, Fan; Wang, Hui; Wang, Qin; Wang, Wenji; Wang, Dong-En; Wang, Jinyi

    2016-07-01

    C3-symmetric truxene and triindole have been widely used to design the branched optoelectronic molecules. However, most of them exhibit high luminous efficiency in the solution and quenched luminescence in the solid state. Here, we respectively chose alkylated truxene and triindole as the central core, 2-methylphenyl as the peripheral functional groups to synthesize three branched compounds. Their photophysical properties have been explored combining with the theoretical calculation. The three compounds exhibit good solubility and high solid-state fluorescence quantum yields. The absorption and emission peaks of triindole compound exhibit apparent red-shift in comparison with those of truxene compounds, which indicates triindole more highly electron delocalization than truxene. The single-crystal structure shows that alkylation of the central core and branched steric bulkiness of these molecules effectively reduce the intermolecular π ⋯ π stacking and avoid the non-radiative transition of these molecules from excited state to ground state in the solid state.

  8. Flow-enhanced solution printing of all-polymer solar cells

    DOE PAGES

    Diao, Ying; Zhou, Yan; Kurosawa, Tadanori; Shaw, Leo; Wang, Cheng; Park, Steve; Guo, Yikun; Reinspach, Julia A.; Gu, Kevin; Gu, Xiaodan; et al

    2015-08-12

    Morphology control of solution coated solar cell materials presents a key challenge limiting their device performance and commercial viability. Here we present a new concept for controlling phase separation during solution printing using an all-polymer bulk heterojunction solar cell as a model system. The key aspect of our method lies in the design of fluid flow using a microstructured printing blade, on the basis of the hypothesis of flow-induced polymer crystallization. Our flow design resulted in a similar to 90% increase in the donor thin film crystallinity and reduced microphase separated donor and acceptor domain sizes. The improved morphology enhancedmore » all metrics of solar cell device performance across various printing conditions, specifically leading to higher short-circuit current, fill factor, open circuit voltage and significantly reduced device-to-device variation. However, we expect our design concept to have broad applications beyond all-polymer solar cells because of its simplicity and versatility.« less

  9. Hydrologic and biogeochemical controls of river subsurface solutes under agriculturally enhanced ground water flow

    USGS Publications Warehouse

    Wildman, R.A.; Domagalski, J.L.; Hering, J.G.

    2009-01-01

    The relative influences of hydrologic processes and biogeochemistry on the transport and retention of minor solutes were compared in the riverbed of the lower Merced River (California, USA). The subsurface of this reach receives ground water discharge and surface water infiltration due to an altered hydraulic setting resulting from agricultural irrigation. Filtered ground water samples were collected from 30 drive point locations in March, June, and October 2004. Hydrologic processes, described previously, were verified by observations of bromine concentrations; manganese was used to indicate redox conditions. The separate responses of the minor solutes strontium, barium, uranium, and phosphorus to these influences were examined. Correlation and principal component analyses indicate that hydrologic processes dominate the distribution of trace elements in the ground water. Redox conditions appear to be independent of hydrologic processes and account for most of the remaining data variability. With some variability, major processes are consistent in two sampling transects separated by 100 m. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  10. Enhanced Spin Squeezing in Atomic Ensembles via Control of the Internal Spin States

    NASA Astrophysics Data System (ADS)

    Shojaee, Ezad; Norris, Leigh; Baragiola, Ben; Montano, Enrique; Hemmer, Daniel; Jessen, Poul; Deutsch, Ivan

    2015-05-01

    Abstract: We study the process by which the collective spin squeezing of an ensemble of Cesium atoms is enhanced by control of the internal spin state of the atoms. By increasing the initial atomic projection noise, one can enhance the Faraday interaction that entangles the atoms with a probe. The light acts as a quantum bus for creating atom-atom entanglement via measurement backaction. Further control can be used to transfer this entanglement to metrologically useful squeezing. We numerically simulate this protocol by a stochastic master equation, including QND measurement and optical pumping, which accounts for decoherence and transfer of coherences between magnetic sub-levels. We study the tradeoff between the enhanced entangling interaction and increased rates of decoherence for different initial state preparations. Under realistic conditions, we find that we can achieve squeezing with a ``CAT-State'' superpostion |F = 4, Mz = 4> + |F, Mz = -4> of ~ 9.9 dB and for the spin coherent state |F = 4, Mx = 4> of ~ 7.5 dB. The increased entanglement enabled by the CAT state preparation is partially, but not completely reduced by the increased fragility to decoherence. National Science Foundation.

  11. Marshak Lectureship Talk: Women in Physics in the Baltic States Region: Problems and Solutions

    NASA Astrophysics Data System (ADS)

    Satkovskiene, Dalia

    2008-03-01

    In this contribution the gender equality problem in physics will be discussed on the basis of the results obtained implementing the project ``Baltic States Network: Women in Sciences and High Technology'' (BASNET) initiated by Lithuanian women physicists and financed by European Commission. The main goal of BASNET project was creation of the regional Strategy how to deal with women in sciences problem in the Baltic States. It has some stages and the contribution follows them. The first one was in depth sociological study aiming to find out disincentives and barriers women scientists face in their career and work at science and higher education institutions. Analysis of results revealed wide range of problems concerned with science organization, management and financing common for both counterparts. However it also proved the existence of women discrimination in sciences. As main factors influencing women under-representation in Physics was found: the stereotypes existing in the society where physics is assigned to the masculine area of activity; failings of the science management system, where highest positions are distributed not using the institutionalized objective criteria but by voting, where the correctness of majority solutions is anticipated implicitly. In physics where male scientists are the majority (they also usually compose executive boards, committees etc.) results of such a procedures often are unfavorable for women. The same reasons also influence women ``visibility'' in physicist's community and as the consequence possibility to receive needed recourses for their research as well as appropriate presentation of results obtained. The study revealed also the conservatism of scientific community- reluctance to face existing in the scientific society problems and to start solving them. On the basis of the results obtained as well practice of other countries the common strategy of solving women in physics (sciences) in the Baltic States region was

  12. A Solution Space for a System of Null-State Partial Differential Equations: Part 2

    NASA Astrophysics Data System (ADS)

    Flores, Steven M.; Kleban, Peter

    2015-01-01

    This article is the second of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE). The system comprises 2 N null-state equations and three conformal Ward identities which govern CFT correlation functions of 2 N one-leg boundary operators. In the first article (Flores and Kleban, Commun Math Phys, arXiv:1212.2301, 2012), we use methods of analysis and linear algebra to prove that dim , with C N the Nth Catalan number. The analysis of that article is complete except for the proof of a lemma that it invokes. The purpose of this article is to provide that proof. The lemma states that if every interval among ( x 2, x 3), ( x 3, x 4),…,( x 2 N-1, x 2 N ) is a two-leg interval of (defined in Flores and Kleban, Commun Math Phys, arXiv:1212.2301, 2012), then F vanishes. Proving this lemma by contradiction, we show that the existence of such a nonzero function implies the existence of a non-vanishing CFT two-point function involving primary operators with different conformal weights, an impossibility. This proof (which is rigorous in spite of our occasional reference to CFT) involves two different types of estimates, those that give the asymptotic behavior of F as the length of one interval vanishes, and those that give this behavior as the lengths of two intervals vanish simultaneously. We derive these estimates by using Green functions to rewrite certain null-state PDEs as integral equations, combining other null-state PDEs to obtain Schauder interior estimates, and then repeatedly integrating the integral equations with these estimates until we obtain optimal bounds. Estimates in which two interval lengths vanish simultaneously divide into two cases: two adjacent intervals and two non-adjacent intervals. The analysis of the latter case is similar to that for one vanishing

  13. Enhanced thermal conduction -- An alternative solution for removing a broad range of hydrocarbons from contaminated soils

    SciTech Connect

    Bova, J.C.

    1999-07-01

    This paper presents an overview of Enhanced Thermal Conduction (ETC), an ex-situ soil remediation process. A review of a practical demonstration of this process which was conducted by Woodward-Clyde Consultants to determine the capability of the technology for remediating soils from gasworks sites that have been contaminated with petroleum hydrocarbons, polynuclear hydrocarbons (PAHs) and cyanide is also presented in this paper. Projections for using this process to treat soils contaminated with other hazardous materials such as TCE PCE and PCB's are discussed as well.

  14. Technical constraints limiting application of enhanced oil recovery techniques to petroleum production in the United States

    SciTech Connect

    Not Available

    1984-01-01

    In the interval since the publication in September 1980 of the technical constraints that inhibit the application of enhanced oil recovery techniques in the United States, there has been a large number of successful field trials of enhanced oil recovery (EOR) techniques. The Department of Energy has shared the costs of 28 field demonstrations of EOR with industry, and the results have been made available to the public through DOE documents, symposiums and the technical literature. This report reexamines the constraints listed in 1980, evaluates the state-of-the-art and outlines the areas where more research is needed. Comparison of the 1980 constraints with the present state-of-the-art indicates that most of the constraints have remained the same; however, the constraints have become more specific. 26 references, 6 tables.

  15. Compact metal probes: a solution for atomic force microscopy based tip-enhanced Raman spectroscopy.

    PubMed

    Rodriguez, R D; Sheremet, E; Müller, S; Gordan, O D; Villabona, A; Schulze, S; Hietschold, M; Zahn, D R T

    2012-12-01

    There are many challenges in accomplishing tip-enhanced Raman spectroscopy (TERS) and obtaining a proper tip is probably the greatest one. Since tip size, composition, and geometry are the ultimate parameters that determine enhancement of intensity and lateral resolution, the tip becomes the most critical component in a TERS experiment. However, since the discovery of TERS the cantilevers used in atomic force microscopy (AFM) have remained basically the same: commercial silicon (or silicon nitride) tips covered by a metallic coating. The main issues of using metal-coated silicon cantilevers, such as wearing off of the metal layer or increased tip radius, can be completely overcome by using all-metal cantilevers. Until now in TERS experiments such probes have only been used in a scanning tunneling microscope or in a tuning fork-based shear force microscope but not in AFM. In this work for the first time, we show the use of compact silver cantilevers that are fully compatible with contact and tapping modes in AFM demonstrating their superb performance in TERS experiments.

  16. Compact metal probes: A solution for atomic force microscopy based tip-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rodriguez, R. D.; Sheremet, E.; Müller, S.; Gordan, O. D.; Villabona, A.; Schulze, S.; Hietschold, M.; Zahn, D. R. T.

    2012-12-01

    There are many challenges in accomplishing tip-enhanced Raman spectroscopy (TERS) and obtaining a proper tip is probably the greatest one. Since tip size, composition, and geometry are the ultimate parameters that determine enhancement of intensity and lateral resolution, the tip becomes the most critical component in a TERS experiment. However, since the discovery of TERS the cantilevers used in atomic force microscopy (AFM) have remained basically the same: commercial silicon (or silicon nitride) tips covered by a metallic coating. The main issues of using metal-coated silicon cantilevers, such as wearing off of the metal layer or increased tip radius, can be completely overcome by using all-metal cantilevers. Until now in TERS experiments such probes have only been used in a scanning tunneling microscope or in a tuning fork-based shear force microscope but not in AFM. In this work for the first time, we show the use of compact silver cantilevers that are fully compatible with contact and tapping modes in AFM demonstrating their superb performance in TERS experiments.

  17. Formic acid enhanced effective degradation of methyl orange dye in aqueous solutions under UV-Vis irradiation.

    PubMed

    Wang, Jingjing; Bai, Renbi

    2016-09-15

    Developing efficient technologies to treat recalcitrant organic dye wastewater has long been of great research and practical interest. In this study, a small molecule, formic acid (FA), was applied as a process enhancer for the degradation of methyl orange (MO) dye as a model recalcitrant organic pollutant in aqueous solutions under the condition of UV-Vis light irradiation and air aeration at the ambient temperature of 25 °C. It was found that the decolouration of the dye solutions can be rapidly achieved, reducing the time, for example, from around 17.6 h without FA to mostly about less than 2 h with the presence of FA. The mineralization rate of MO dye reached as high as 81.8% in 1.5 h in the case of initial MO dye concentration at 25 mg L(-1), which is in contrast to nearly no mineralization of the MO dye for a similar system without the FA added. The study revealed that the generation of the H2O2 species in the system was enhanced and the produced OH radicals effectively contributed to the degradation of the MO dye. Process parameters such as the initial concentration of MO dye, FA dosage and solution pH were all found to have some effect on the degradation efficiency under the same condition of UV-Vis light irradiation and air aeration. The MO dye degradation performance was found to follow a first-order reaction rate to the MO dye concentration in most cases and there existed a positive correlation between the reaction rate constant and the initial FA concentration. Compared to the traditional H2O2/UV-Vis oxidation system, the use of FA as a process-enhancing agent can have the advantages of low cost, easy availability, and safe to use. The study hence demonstrates a promising approach to use a readily available small molecule of FA to enhance the degradation of recalcitrant organic pollutants, such as MO dye, especially for their pre-treatment. PMID:27258621

  18. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with (pyrazol-1-yl)acetic acid.

    PubMed

    Chen, Xiao-Yan; Goff, George S; Scott, Brian L; Janicke, Michael T; Runde, Wolfgang

    2013-03-18

    As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Two distinct crystallographic structures are governed by the different coordination modes of carboxylate groups in L: terminal bidentate and bridging tridentate (1-3); terminal bidentate, bridging bidentate, and tridentate coordination in 4. Comparison of the solid state UV-vis-NIR diffuse reflectance spectra with solution state UV-vis-NIR spectra suggests a different species in solution and solid state. The different coordination in solid state and solution was verified by distinctive (13)C NMR signals of the carboxylate groups in the solid state NMR.

  19. New steady-state models for water-limited cropping systems using saline irrigation waters: Analytical solutions and applications

    NASA Astrophysics Data System (ADS)

    Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.

    2014-12-01

    Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two new explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess clear advantages over available alternatives, including: (i) the new solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the new analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.

  20. Localized surface plasmon for enhanced lasing performance in solution-processed perovskites.

    PubMed

    Kao, Tsung Sheng; Hong, Kuo-Bin; Chou, Yu-Hsun; Huang, Jiong-Fu; Chen, Fang-Chung; Lu, Tien-Chang

    2016-09-01

    A promising method to promote the lasing performance of solution-processed organic-inorganic lead-halide perovskites has been demonstrated. With the adding Ag and PMMA thin films, the threshold excitation power for low-temperature lasing action in perovskites can be greatly reduced by over two orders of magnitude than that acquired in bare perovskite layers, ascribing to the strong exciton-plasmon coupling between the Ag and perovskite films. Also, the PMMA layer can be exploited to prevent the perovskite degradation from the hydrolysis in ambient environment, achieving long-lasting light-emitting performance. The advantages exhibited by the hybrid perovskite configuration would be very promising in making practical laser devices. PMID:27607673

  1. X-ray computed tomography system for laboratory small-object imaging: Enhanced tomography solutions.

    PubMed

    Kharfi, F; Yahiaoui, M L; Boussahoul, F

    2015-07-01

    A portable X-ray tomography system has been installed and actually being tested at our medical imaging laboratory. This tomography system employs a combination of scintillator screen and CCD camera as image detector. The limit of spatial resolution of 290 μm of this imaging system is determined by the establishment of its modulation transfer function (MTF). In this work, we present attempts to address some issues such as limited resolution and low contrast through the development of affordable post-acquisition solutions based on the application of super-resolution method (projection onto convex sets, POCS) to create new projections set enabling the reconstruction of an improved 3D image in terms of contrast, resolution and noise. In addition to small-object examination, this tomography system is used for hands-on training activities involving students and scientists.

  2. Enhanced removal of nickel(II) ions from aqueous solutions by SDS-functionalized graphene oxide

    PubMed Central

    Salihi, Elif Çalışkan; Wang, Jiabin; Coleman, Daniel J. L.; Šiller, Lidija

    2016-01-01

    ABSTRACT In this paper, a one-pot and easy-to-handle method at room temperature without additional chemicals for the modification of graphene oxide (GO) with surfactant is found. Removal of nickel (II) ions from aqueous solutions by GO and surfactant (sodium dodecyl sulphate) modified graphene oxide (SDS-GO) was studied spectrophotometrically at room temperature as a function of time, initial concentration and pH. Adsorption capacity of the adsorbent was increased dramatically (from 20.19 to 55.16 mg/g found by Langmuir model) due to the functionalization of the surface by SDS. The driving force of the adsorption of Ni(II) ions is electrostatic attraction and Ni(II) ions adsorbed on the GO surface chemically besides ion exchange. PMID:27365545

  3. Pr(III) luminescence enhancement by chelation in solution and in sol-gel glass

    NASA Astrophysics Data System (ADS)

    Zaitoun, M. A.; El-Qisairi, A. K.; Momani, K. A.; Qaseer, H. A.; Jaradat, Q. M.

    2015-02-01

    Due to the weak emission of lanthanide ions in solution, it is common practice to form complexes of the lanthanide ions with organic ligands that strongly absorbs light and transfers the energy to the lanthanide ion center via the antenna effect. The organic ligands 2-6-pyridinedicarboxylate (L1) and the polytonic diazine (N-N) ligand L2 (C22H16N12O2) were used to synthesize two Pr(III) complexes, namely: Pr-L1 (Na3[Pr(C7H3NO4)3]) and Pr-L2. The prepared complexes were further encapsulated in an optically transparent sol-gel glass. The synthesized ligands and complexes were characterized by FTIR and 1H NMR. Room temperature luminescence of Pr-L1 and Pr-L2 complexes in solution and in sol-gel glass were investigated using a spectrofluorometer. Excitation at the maximum absorption wavelength of the ligands (280 nm) resulted in the typical visible luminescence (centered at around 600 nm) resulting from the 1D2 → 3H4 transition of the Pr(III) ion, which contributes to the efficient energy transfer from the absorbing ligand L1 to the chelated Pr(III) ion (an antenna effect) while the Pr(III) luminescence is not efficiently sensitized by ligand L2. The obtained emission spectra indicated that the excitation energy level for the central Pr(III) is in a slightly lower location than ligand L1 excitation triplet (T1) level and can accept the energy transfer from T1 efficiently.

  4. Pr(III) luminescence enhancement by chelation in solution and in sol-gel glass.

    PubMed

    Zaitoun, M A; El-Qisairi, A K; Momani, K A; Qaseer, H A; Jaradat, Q M

    2015-02-01

    Due to the weak emission of lanthanide ions in solution, it is common practice to form complexes of the lanthanide ions with organic ligands that strongly absorbs light and transfers the energy to the lanthanide ion center via the antenna effect. The organic ligands 2-6-pyridinedicarboxylate (L1) and the polytonic diazine (N-N) ligand L2 (C22H16N12O2) were used to synthesize two Pr(III) complexes, namely: Pr-L1 (Na3[Pr(C7H3NO4)3]) and Pr-L2. The prepared complexes were further encapsulated in an optically transparent sol-gel glass. The synthesized ligands and complexes were characterized by FTIR and (1)H NMR. Room temperature luminescence of Pr-L1 and Pr-L2 complexes in solution and in sol-gel glass were investigated using a spectrofluorometer. Excitation at the maximum absorption wavelength of the ligands (280nm) resulted in the typical visible luminescence (centered at around 600nm) resulting from the (1)D2→(3)H4 transition of the Pr(III) ion, which contributes to the efficient energy transfer from the absorbing ligand L1 to the chelated Pr(III) ion (an antenna effect) while the Pr(III) luminescence is not efficiently sensitized by ligand L2. The obtained emission spectra indicated that the excitation energy level for the central Pr(III) is in a slightly lower location than ligand L1 excitation triplet (T1) level and can accept the energy transfer from T1 efficiently. PMID:25467665

  5. Introduction of bifunctional groups into mesoporous silica for enhancing uptake of thorium(IV) from aqueous solution.

    PubMed

    Yuan, Li-Yong; Bai, Zhi-Qiang; Zhao, Ran; Liu, Ya-Lan; Li, Zi-Jie; Chu, Sheng-Qi; Zheng, Li-Rong; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-04-01

    The potential industrial application of thorium (Th), as well as the environmental and human healthy problems caused by thorium, promotes the development of reliable methods for the separation and removal of Th(IV) from environmental and geological samples. Herein, the phosphonate-amino bifunctionalized mesoporous silica (PAMS) was fabricated by a one-step self-assembly approach for enhancing Th(IV) uptake from aqueous solution. The synthesized sorbent was found to possess ordered mesoporous structures with uniform pore diameter and large surface area, characterized by SEM, XRD, and N2 sorption/desorption measurements. The enhancement of Th(IV) uptake by PAMS was achieved by coupling of an access mechanism to a complexation mechanism, and the sorption can be optimized by adjusting the coverage of the functional groups in the PAMS sorbent. The systemic study on Th(IV) sorption/desorption by using one coverage of PAMS (PAMS12) shows that the Th(IV) sorption by PAMS is fast with equilibrium time of less than 1 h, and the sorption capacity is more than 160 mg/g at a relatively low pH. The sorption isotherm has been successfully modeled by the Langmuir isotherm and D-R isotherm, which reveals a monolayer homogeneous chemisorption of Th(IV) in PAMS. The Th(IV) sorption by PAMS is pH dependent but ionic strength independent. In addition, the sorbed Th(IV) can be completely desorbed using 0.2 mol/L or more concentrated nitric acid solution. The sorption test performed in the solution containing a range of competing metal ions suggests that the PAMS sorbent has a desirable selectivity for Th(IV) ions.

  6. Enhanced Molecular Recognition between Nucleobases and Guanine-5'-monophosphate-disodium (GMP) by Surfactant Aggregates in Aqueous Solution.

    PubMed

    Liu, Zhang; Wang, Dong; Cao, Meiwen; Han, Yuchun; Xu, Hai; Wang, Yilin

    2015-07-15

    Only specific base pairs on DNA can bind with each other through hydrogen bonds, which is called the Watson-Crick (W/C) pairing rule. However, without the constraint of DNA chains, the nucleobases in bulk aqueous solution usually do not follow the W/C pairing rule anymore because of the strong competitive effect of water and the multi-interaction edges of nucleobases. The present work applied surfactant aggregates noncovalently functionalized by nucleotide to enhance the recognition between nucleobases without DNA chains in aqueous solution, and it revealed the effects of their self-assembling ability and morphologies on the recognition. The cationic ammonium monomeric, dimeric, and trimeric surfactants DTAB, 12-3-12, and 12-3-12-3-12 were chosen. The surfactants with guanine-5'-monophosphate-disodium (GMP) form micelles, vesicles, and fingerprint-like and plate-like aggregates bearing the hydrogen-bonding sites of GMP, respectively. The binding parameters of these aggregates with adenine (A), uracil (U), guanine (G), and cytosine(C) indicate that the surfactants can promote W/C recognitions in aqueous solution when they form vesicles (GMP/DTAB) or plate-like aggregates (GMP/12-3-12) with proper molecular packing compactness, which not only provide hydrophobic environments but also shield non-W/C recognition edges. However, the GMP/12-3-12 micelles with loose molecular packing, the GMP/12-3-12 fingerprint-like aggregates where the hydrogen bond sites of GMP are occupied by itself, and the GMP/12-3-12-3-12 vesicles with too strong self-assembling ability cannot promote W/C recognition. This work provides insight into how to design self-assemblies with the performance of enhanced molecule recognition.

  7. Solution and solid state NMR approaches to draw iron pathways in the ferritin nanocage.

    PubMed

    Lalli, Daniela; Turano, Paola

    2013-11-19

    Ferritins are intracellular proteins that can store thousands of iron(III) ions as a solid mineral. These structures autoassemble from four-helix bundle subunits to form a hollow sphere and are a prototypical example of protein nanocages. The protein acts as a reservoir, encapsulating iron as ferric oxide in its central cavity in a nontoxic and bioavailable form. Scientists have long known the structural details of the protein shell, owing to very high resolution X-ray structures of the apoform. However, the atomic level mechanism governing the multistep biomineralization process remained largely elusive. Through analysis of the chemical behavior of ferritin mutants, chemists have found the role of some residues in key reaction steps. Using Mössbauer and XAS, they have identified some di-iron intermediates of the catalytic reaction trapped by rapid freeze quench. However, structural information about the iron interaction sites remains scarce. The entire process is governed by a number of specific, but weak, interactions between the protein shell and the iron species moving across the cage. While this situation may constitute a major problem for crystallography, NMR spectroscopy represents an optimal tool to detect and characterize transient species involving soluble proteins. Regardless, NMR analysis of the 480 kDa ferritin represents a real challenge. Our interest in ferritin chemistry inspired us to use an original combination of solution and solid state approaches. While the highly symmetric structure of the homo-24-mer frog ferritin greatly simplifies the spectra, the large protein size hinders the efficient coherence transfer in solution, thus preventing the sequence specific assignments. In contrast, extensive (13)C-spin diffusion makes the solution (13)C-(13)C NOESY experiment our gold standard to monitor protein side chains both in the apoprotein alone and in its interaction with paramagnetic iron species, inducing line broadening on the resonances of

  8. Mechanisms behind injecting the combination of nano-clay particles and polymer solution for enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Khalili Nezhad, Seyyed Shahram; Cheraghian, Goshtasp

    2016-08-01

    Laboratory investigations and field applications have proved injection of polymer solution to be an effective means to improve oil recovery for reservoirs of medium oil viscosity. The incremental oil produced in this case is the result of an increase in areal and vertical sweep efficiencies. Biopolymers and synthetic polymers are the major categories used in the petroleum industry for specific reasons. Biopolymers like xanthan are limited in their application as they are more susceptible to biodegradation. Synthetic polymers like Hydrolyzed PolyAcrylaMide (HPAM) have a much wider application as they are less susceptible to biodegradation. Furthermore, development of nanotechnology has successfully provided technical and economical viable alternatives for present materials. The objective of this study is to investigate the effect of combining clay nanoparticles with polymer solution on oil recovery. This paper includes a history match of both one-dimensional and two-dimensional polymer floods using a three-dimensional numerical model for fluid flow and mass transport. Results indicated that the amount of polymer adsorption decreased when clay nanoparticles were added to the PolyAcrylaMide solution; however, mobility ratio improvement is believed to be the main contributor for the proposed method in order to enhance much oil recovery compared to xanthan flood and HPAM flood.

  9. Degradation of a monoazo dye Alizarin Yellow GG in aqueous solutions by gamma irradiation: Decolorization and biodegradability enhancement

    NASA Astrophysics Data System (ADS)

    Sun, Weihua; Chen, Lujun; Tian, Jinping; Wang, Jianlong; He, Shijun

    2013-02-01

    The irradiation-induced degradation of an azo dye, Alizarin Yellow GG (AY-GG), was investigated in aqueous solution under gamma irradiation using a 60Cobalt source at a dose rate of 113 Gy/min. The decolorization percentage of AY-GG reached 65% when its initial concentration was 100 mg/l and the absorbed dose was 9 kGy. The decolorization process could be described by first-order kinetic equation. In addition, specific oxygen uptake rate (SOUR, mg O2 (g MLVSS)-1 h-1) of activated sludge using the irradiated azo dye solutions was 8.1 mg O2 (g MLVSS)-1 h-1 after 9 kGy irradiation, indicating that the biodegradability of AY-GG could be enhanced by 30%. However, toxic intermediates including heterocyclic aromatic amines and cyanides were detected during the irradiation process, which inhibited the complete biological degradation of azo dye. Fortunately, the inhibition could be eliminated by further irradiation. The azo dye solution became amenable to biodegradation and can be further treated by biological treatment process.

  10. Disentangling detector data in XFEL studies of temporally resolved solution state chemistry.

    PubMed

    Brandt van Driel, Tim; Kjær, Kasper Skov; Biasin, Elisa; Haldrup, Kristoffer; Lemke, Henrik Till; Nielsen, Martin Meedom

    2015-01-01

    With the arrival of X-ray Free Electron Lasers (XFELs), 2D area detectors with a large dynamic range for detection of hard X-rays with fast readout rates are required for many types of experiments. Extracting the desired information from these detectors has been challenging due to unpredicted fluctuations in the measured images. For techniques such as time-resolved X-ray Diffuse Scattering (XDS), small differences in signal intensity are the starting point for analysis. Fluctuations in the total detected signal remain in the differences under investigation, obfuscating the signal. To correct such artefacts, Singular Value Decomposition (SVD) can be used to identify and characterize the observed detector fluctuations and assist in assigning some of them to variations in physical parameters such as X-ray energy and X-ray intensity. This paper presents a methodology for robustly identifying, separating and correcting fluctuations on area detectors based on XFEL beam characteristics, to enable the study of temporally resolved solution state chemistry on the femtosecond timescale.

  11. Disentangling detector data in XFEL studies of temporally resolved solution state chemistry.

    PubMed

    Brandt van Driel, Tim; Kjær, Kasper Skov; Biasin, Elisa; Haldrup, Kristoffer; Lemke, Henrik Till; Nielsen, Martin Meedom

    2015-01-01

    With the arrival of X-ray Free Electron Lasers (XFELs), 2D area detectors with a large dynamic range for detection of hard X-rays with fast readout rates are required for many types of experiments. Extracting the desired information from these detectors has been challenging due to unpredicted fluctuations in the measured images. For techniques such as time-resolved X-ray Diffuse Scattering (XDS), small differences in signal intensity are the starting point for analysis. Fluctuations in the total detected signal remain in the differences under investigation, obfuscating the signal. To correct such artefacts, Singular Value Decomposition (SVD) can be used to identify and characterize the observed detector fluctuations and assist in assigning some of them to variations in physical parameters such as X-ray energy and X-ray intensity. This paper presents a methodology for robustly identifying, separating and correcting fluctuations on area detectors based on XFEL beam characteristics, to enable the study of temporally resolved solution state chemistry on the femtosecond timescale. PMID:25675434

  12. Chain length dependent excited-state decay processes of diluted PF2/6 solutions.

    PubMed

    Pina, João; Seixas de Melo, J Sérgio; Koenen, Niels; Scherf, Ulli

    2013-06-20

    The excited-state dynamics of a series of four poly[2,7-(9,9-bis(2-ethylhexyl)fluorene] fractions, PF2/6, with different chain length (degrees of polymerization DP: 5, 10, 39, and 205) was investigated in dilute solutions by steady-state and time-resolved fluorescence techniques. Two decay components are extracted from time-resolved fluorescence experiments in the picosecond time domain: a chain length dependent, fast decay time (τ(2)) for shorter emission wavelengths (ranging from 30 to 41 ps), which is associated with a rising component at longer wavelengths, and a longer decay time, τ(1) (ranging from 387 to 452 ps). The system was investigated with kinetic formalisms involving (i) a two-state system (A and B) involving conformational relaxation of the initially excited PF2/6 segment (A) under formation of a more planar (B) relaxed state and (ii) a time-dependent red shift of the emission spectrum using the Stokes shift correlation function (SSCF). In the case of (i), the kinetic scheme was solved considering the simultaneous excitation of A and B or only of A, and the rate constants for formation [k′(CR) or k′(CR)(α)], dissociation (k(–CR)), and deactivation (k(B)(*)) were obtained together with the fraction of species A and B present in the ground state. The use of the SSCF in (ii) was found to be more adequate leading to a decay law with a 3.4 ps component (associated with the slow part of the solvation dynamics process) and a longer decay (43.3 ps) associated with the conformational/torsional relaxation process with a rate constant k(CR). This longer component of the SSCF was found to be identical to the short-living decay (τ(2)) component of the biexponential decays, displaying an Arrhenius-type behavior with activation energy values in the range 5.8–8.9 kJ mol(–1) in toluene and 6.5–10.7 kJ mol(–1) in decalin. From the dependence of the fast decay component (k(CR) ≡ 1/τ(2)) on solvent viscosity and temperature, the activation energy

  13. Enhanced removal of 8-quinolinecarboxylic acid in an activated carbon cloth by electroadsorption in aqueous solution.

    PubMed

    López-Bernabeu, S; Ruiz-Rosas, R; Quijada, C; Montilla, F; Morallón, E

    2016-02-01

    The effect of the electrochemical treatment (potentiostatic treatment in a filter-press electrochemical cell) on the adsorption capacity of an activated carbon cloth (ACC) was analyzed in relation with the removal of 8-quinolinecarboxylic acid pollutant from water. The adsorption capacity of an ACC is quantitatively improved in the presence of an electric field (electroadsorption process) reaching values of 96% in comparison to 55% in absence of applied potential. In addition, the cathodic treatment results in higher removal efficiencies than the anodic treatment. The enhanced adsorption capacity has been proved to be irreversible, since the removed compound remains adsorbed after switching the applied potential. The kinetics of the adsorption processes is also improved by the presence of an applied potential. PMID:26433936

  14. Large scale solution assembly of quantum dot-gold nanorod architectures with plasmon enhanced fluorescence.

    PubMed

    Nepal, Dhriti; Drummy, Lawrence F; Biswas, Sushmita; Park, Kyoungweon; Vaia, Richard A

    2013-10-22

    Tailoring the efficiency of fluorescent emission via plasmon-exciton coupling requires structure control on a nanometer length scale using a high-yield fabrication route not achievable with current lithographic techniques. These systems can be fabricated using a bottom-up approach if problems of colloidal stability and low yield can be addressed. We report progress on this pathway with the assembly of quantum dots (emitter) on gold nanorods (plasmonic units) with precisely controlled spacing, quantum dot/nanorod ratio, and long-term colloidal stability, which enables the purification and encapsulation of the assembled architecture in a protective silica shell. Overall, such controllability with nanometer precision allows one to synthesize stable, complex architectures at large volume in a rational and controllable manner. The assembled architectures demonstrate photoluminescent enhancement (5×) useful for applications ranging from biological sensing to advanced optical communication.

  15. Enhanced removal of 8-quinolinecarboxylic acid in an activated carbon cloth by electroadsorption in aqueous solution.

    PubMed

    López-Bernabeu, S; Ruiz-Rosas, R; Quijada, C; Montilla, F; Morallón, E

    2016-02-01

    The effect of the electrochemical treatment (potentiostatic treatment in a filter-press electrochemical cell) on the adsorption capacity of an activated carbon cloth (ACC) was analyzed in relation with the removal of 8-quinolinecarboxylic acid pollutant from water. The adsorption capacity of an ACC is quantitatively improved in the presence of an electric field (electroadsorption process) reaching values of 96% in comparison to 55% in absence of applied potential. In addition, the cathodic treatment results in higher removal efficiencies than the anodic treatment. The enhanced adsorption capacity has been proved to be irreversible, since the removed compound remains adsorbed after switching the applied potential. The kinetics of the adsorption processes is also improved by the presence of an applied potential.

  16. Enhanced permeation of fentanyl from supersaturated solutions in a model membrane.

    PubMed

    Santos, P; Watkinson, A C; Hadgraft, J; Lane, M E

    2011-04-01

    The aim of the present study was to investigate the permeation of fentanyl from supersaturated formulations when applied to silicone membrane. Silicone was chosen in order to separate the effects of supersaturation from other possible influences of volatile formulation components on biological membranes. Supersaturated formulations containing either propylene glycol/water (PG/H(2)O) or propylene glycol/ethanol (PG/Et) were prepared containing varying degrees of saturation (DS) of fentanyl. Permeation of finite and infinite doses of the PG/H(2)O formulations, and finite doses of the PG/Et formulations was investigated using Franz-type diffusion cells. For the PG/H(2)O formulations a good correlation between the flux and the DS of the formulation up to 5 DS for infinite dose studies (r(2)=0.99), and up to 7 DS for finite dose studies (r(2)=0.98), was evident. Similarly, for the PG/Et formulations there is a good correlation between the mean flux and the theoretical DS of the formulation (r(2)=0.95). Except for the 2 DS formulations, no significant differences were seen in the mean flux between PG/H(2)O and PG/Et finite dose studies. The larger fluxes observed for infinite doses of the PG/H(2)O formulations versus finite doses reflect changes in the effective area of diffusion over the time of the experiment for the latter set of experiments. The permeation enhancement observed for PG/Et formulations confirms that enhanced drug thermodynamic activity was induced by ethanol evaporation. PMID:21256946

  17. Excited-state dynamics of guanosine in aqueous solution revealed by time-resolved photoelectron spectroscopy: experiment and theory.

    PubMed

    Buchner, Franziska; Heggen, Berit; Ritze, Hans-Hermann; Thiel, Walter; Lübcke, Andrea

    2015-12-21

    Time-resolved photoelectron spectroscopy is performed on aqueous guanosine solution to study its excited-state relaxation dynamics. Experimental results are complemented by surface hopping dynamic simulations and evaluation of the excited-state ionization energy by Koopmans' theorem. Two alternative models for the relaxation dynamics are discussed. The experimentally observed excited-state lifetime is about 2.5 ps if the molecule is excited at 266 nm and about 1.1 ps if the molecule is excited at 238 nm. The experimental probe photon energy dependence of the photoelectron kinetic energy distribution suggests that the probe step is not vertical and involves a doubly-excited autoionizing state.

  18. Comparative analysis of zaleplon complexation with cyclodextrins and hydrophilic polymers in solution and in solid state.

    PubMed

    Jablan, Jasna; Szalontai, Gábor; Jug, Mario

    2012-12-01

    The aim of this work was to investigate the potential synergistic effect of water-soluble polymers (hypromellose, HPMC and polyvinylpyrrolidone, PVP) on zaleplon (ZAL) complexation with parent β-cyclodextrin (βCD) and its randomly methylated derivative (RAMEB) in solution and in solid state. The addition of HPMC to the complexation medium improved ZAL complexation and solubilization with RAMEB (K(ZAL/RAMEB)=156±5M(-1) and K(ZAL/RAMEB/HPMC)=189±8M(-1); p<0.01), while such effect was not observed for βCD (K(ZAL/βCD)=112±2M(-1) and K(ZAL/βCD/HPMC)=119±8M(-1); p>0.05). Although PVP increased the ZAL aqueous solubility from 0.22 to 0.27mg/mL, it did not show any synergistic effects on ZAL solubilization with the cyclodextrins tested. Binary and ternary systems of ZAL with βCD, RAMEB and HPMC were prepared by spray-drying. Differential scanning calorimetry, X-ray powder diffraction and scanning electron microscopy demonstrated a partial ZAL amorphization in spray-dried binary and ternary systems with βCD, while the drug was completely amorphous in all samples with RAMEB. Furthermore, inclusion complex formation in all systems prepared was confirmed by solid-state NMR spectroscopy. The in vitro dissolution rate followed the rank order ZAL/RAMEB/HPMC>ZAL/RAMEB=ZAL/βCD/HPMC>ZAL/βCD≫ZAL, clearly demonstrating the superior performance of RAMEB on ZAL complexation in the solid state and its synergistic effect with HPMC on drug solubility. Surprisingly, when loaded into tablets made with insoluble microcrystalline cellulose, RAMEB complexes had no positive effect on drug dissolution, because HPMC and RAMEB acted as a binders inside the tablets, prolonging their disintegration. Oppositely, the formulation with mannitol, a soluble excipient, containing a ternary RAMEB system, released the complete drug-dose in only 5min, clearly demonstrating its suitability for the development of immediate-release oral formulation of ZAL.

  19. Simultaneous tDCS-fMRI Identifies Resting State Networks Correlated with Visual Search Enhancement

    PubMed Central

    Callan, Daniel E.; Falcone, Brian; Wada, Atsushi; Parasuraman, Raja

    2016-01-01

    This study uses simultaneous transcranial direct current stimulation (tDCS) and functional MRI (fMRI) to investigate tDCS modulation of resting state activity and connectivity that underlies enhancement in behavioral performance. The experiment consisted of three sessions within the fMRI scanner in which participants conducted a visual search task: Session 1: Pre-training (no performance feedback), Session 2: Training (performance feedback given), Session 3: Post-training (no performance feedback). Resting state activity was recorded during the last 5 min of each session. During the 2nd session one group of participants underwent 1 mA tDCS stimulation and another underwent sham stimulation over the right posterior parietal cortex. Resting state spontaneous activity, as measured by fractional amplitude of low frequency fluctuations (fALFF), for session 2 showed significant differences between the tDCS stim and sham groups in the precuneus. Resting state functional connectivity from the precuneus to the substantia nigra, a subcortical dopaminergic region, was found to correlate with future improvement in visual search task performance for the stim over the sham group during active stimulation in session 2. The after-effect of stimulation on resting state functional connectivity was measured following a post-training experimental session (session 3). The left cerebellum Lobule VIIa Crus I showed performance related enhancement in resting state functional connectivity for the tDCS stim over the sham group. The ability to determine the relationship that the relative strength of resting state functional connectivity for an individual undergoing tDCS has on future enhancement in behavioral performance has wide ranging implications for neuroergonomic as well as therapeutic, and rehabilitative applications. PMID:27014014

  20. On modeling of chemical stimulation of an enhanced geothermal system using a high pH solution with chelating agent

    SciTech Connect

    Xu, T.; Rose, P.; Fayer, S.; Pruess, K.

    2009-05-01

    Dissolution of silica and calcite in the presence of a chelating agent (NTA) at a high pH was successfully demonstrated in laboratory experiments using a high-temperature flow reactor. (Note that the term 'silica' used here includes amorphous silica, quartz, and silicate glass bead). The mineral dissolution and associated porosity enhancement in the experiments were reproduced by reactive transport modeling using TOUGHREACT. The chemical stimulation method was applied by numerical modeling to a field geothermal injection well system to investigate its effectiveness. Parameters applicable to the quartz monzodiorite unit at the Enhanced Geothermal Systems (EGS) site at Desert Peak (Nevada) were used. Results indicate that the injection of a high pH chelating solution results in dissolution of both calcite and plagioclase, while avoiding precipitation of calcite at high temperature conditions. Consequently reservoir porosity and permeability can be enhanced especially near the injection well. Injection at a lower temperature of 120 C (over 160 C in the base-case) results in a porosity increase that is smaller close to the injection point, but extends to a larger radial distance. A slower kinetic rate results in less aggressive mineral dissolution close to the injection point and larger extent along the flow path, which is favorable for chemical stimulation.

  1. Matching Solid-State to Solution-Phase Photoluminescence for Near-Unity Down-Conversion Efficiency Using Giant Quantum Dots.

    PubMed

    Hanson, Christina J; Buck, Matthew R; Acharya, Krishna; Torres, Joseph A; Kundu, Janardan; Ma, Xuedan; Bouquin, Sarah; Hamilton, Christopher E; Htoon, Han; Hollingsworth, Jennifer A

    2015-06-24

    Efficient, stable, and narrowband red-emitting fluorophores are needed as down-conversion materials for next-generation solid-state lighting that is both efficient and of high color quality. Semiconductor quantum dots (QDs) are nearly ideal color-shifting phosphors, but solution-phase efficiencies have not traditionally extended to the solid-state, with losses from both intrinsic and environmental effects. Here, we assess the impacts of temperature and flux on QD phosphor performance. By controlling QD core/shell structure, we realize near-unity down-conversion efficiency and enhanced operational stability. Furthermore, we show that a simple modification of the phosphor-coated light-emitting diode device-incorporation of a thin spacer layer-can afford reduced thermal or photon-flux quenching at high driving currents (>200 mA).

  2. Implementation into earthquake sequence simulations of a rate- and state-dependent friction law incorporating pressure solution creep

    NASA Astrophysics Data System (ADS)

    Noda, H.

    2016-05-01

    Pressure solution creep (PSC) is an important elementary process in rock friction at high temperatures where solubilities of rock-forming minerals are significantly large. It significantly changes the frictional resistance and enhances time-dependent strengthening. A recent microphysical model for PSC-involved friction of clay-quartz mixtures, which can explain a transition between dilatant and non-dilatant deformation (d-nd transition), was modified here and implemented in dynamic earthquake sequence simulations. The original model resulted in essentially a kind of rate- and state-dependent friction (RSF) law, but assumed a constant friction coefficient for clay resulting in zero instantaneous rate dependency in the dilatant regime. In this study, an instantaneous rate dependency for the clay friction coefficient was introduced, consistent with experiments, resulting in a friction law suitable for earthquake sequence simulations. In addition, a term for time-dependent strengthening due to PSC was added which makes the friction law logarithmically rate-weakening in the dilatant regime. The width of the zone in which clasts overlap or, equivalently, the interface porosity involved in PSC plays a role as the state variable. Such a concrete physical meaning of the state variable is a great advantage in future modelling studies incorporating other physical processes such as hydraulic effects. Earthquake sequence simulations with different pore pressure distributions demonstrated that excess pore pressure at depth causes deeper rupture propagation with smaller slip per event and a shorter recurrence interval. The simulated ruptures were arrested a few kilometres below the point of pre-seismic peak stress at the d-nd transition and did not propagate spontaneously into the region of pre-seismic non-dilatant deformation. PSC weakens the fault against slow deformation and thus such a region cannot produce a dynamic stress drop. Dynamic rupture propagation further down to

  3. Ion beam treatment of titanium surfaces for enhancing deposition of hydroxyapatite from solution.

    PubMed

    Maitz, M F; Pham, M T; Matz, W; Reuther, H; Steiner, G; Richter, E

    2002-08-01

    Surface coating with hydroxyapatite (HA) is a common way to improve the osseointegration of orthopaedic and dental titanium (Ti)-based materials. The main problems with current techniques are changes in composition during heating and poor adhesion to the surface. An alternative method is deposition of HA onto an activated surface out of a solution. The present work studies the surface treatment involving ion implantation of Na into Ti to induce a modification in chemistry and morphology, showing sodium titanate (Na(2)TiO(3)) incorporated within the surface layer with concentration, depth distribution, and morphology depending on the parameters of the ion implantation. Such ion-implanted Ti surfaces actively induce heterogeneous precipitation of HA from a simulated body fluid containing physiological concentrations of calcium and phosphate ions. This is compared with the activation by NaOH etching. The growth of bone forming cells on the pure Na implanted surface is oriented without an increased bone formation. Cell growth on the NaOH etched surface is reduced. After deposition of HA on both surfaces cell the growth pattern was improved.

  4. Enhancing the biological degradability of sulfamethoxazole by ionizing radiation treatment in aqueous solution

    NASA Astrophysics Data System (ADS)

    Sági, Gyuri; Kovács, Krisztina; Bezsenyi, Anikó; Csay, Tamás; Takács, Erzsébet; Wojnárovits, László

    2016-07-01

    Changes of biodegradability and toxicity were followed up on aqueous solutions of sulfamethoxazole (SMX), during ionizing radiation treatment. The biodegradability of SMX (0.1 mmol dm-3) was specified by five-day biological oxygen demand (BOD5), using municipal activated sludge, and the results showed an improvement with applying only 0.4 kGy dose. BOD5 further increased with prolonged irradiation, indicating a conversion of SMX, a non-biodegradable compound, to biologically treatable substances. At 2.5 kGy dose, the BOD5/COD ratio increased from 0 to 0.16. The total organic carbon (TOC) content showed a decrease of only 15% at this point, thus high degree of mineralization is not necessary to make SMX digestible for the low concentrations of microorganisms used during BOD5 measurements. Increment in respiration inhibition of municipal activated sludge was observed with increasing the dose. The EC50 values showed a decrease of one order of magnitude when changing the dose from 0.4 kGy to 2.5 kGy. The increase of inhibition and formation of H2O2 showed a strong correlation.

  5. Perovskite solid solutions with multiferroic morphotropic phase boundaries and property enhancement

    NASA Astrophysics Data System (ADS)

    Algueró, M.; Amorín, H.; Fernández-Posada, C. M.; Peña, O.; Ramos, P.; Vila, E.; Castro, A.

    2016-05-01

    Recently, large phase-change magnetoelectric response has been anticipated by a first-principles investigation of phases in the BiFeO3-BiCoO3 perovskite binary system, associated with the existence of a discontinuous morphotropic phase boundary (MPB) between multiferroic polymorphs of rhombohedral and tetragonal symmetries. This might be a general property of multiferroic phase instabilities, and a novel promising approach for room temperature magnetoelectricity. We review here our current investigations on the identification and study of additional material systems, alternative to BiFeO3-BiCoO3 that has only been obtained by high pressure synthesis. Three systems, whose phase diagrams were, in principle, liable to show multiferroic MPBs have been addressed: the BiMnO3-PbTiO3 and BiFeO3-PbTiO3 binary systems, and the BiFeO3-BiMnO3-PbTiO3 ternary one. A comprehensive study of multiferroism across different solid solutions was carried out based on electrical and magnetic characterizations, complemented with mechanical and electromechanical measurements. An in-depth structural analysis was also accomplished when necessary.

  6. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  7. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2014-07-01

    A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

  8. Resolution enhancement of suspended microchannel resonators for weighing of biomolecular complexes in solution.

    PubMed

    Modena, Mario M; Wang, Yu; Riedel, Dietmar; Burg, Thomas P

    2014-01-21

    We introduce the use of correlation analysis to extend the dynamic range of suspended micro- and nanochannel resonator (SMR/SNR) mass sensors by over five orders of magnitude. This method can analyze populations of particles flowing through an embedded channel micromechanical resonator, even when the individual particle masses are far below the noise floor. To characterize the method, we measured the mass of polystyrene nanoparticles with 300 zg resolution. As an application, we monitored the time course of insulin amyloid formation from pre-fibrillar aggregates to mature fibrils of 15 MDa average mass. Results were compared with thioflavin-T (ThT) assays and electron microscopy (EM). Mass measurements offer additional information over ThT during the fluorescent inaccessible lag period, and the average fibril dimensions calculated from the mass signal are in good accordance with EM. In the future, we envision that more detailed modeling will allow the computational deconvolution of multicomponent samples, enabling the mass spectrometric characterization of a variety of biomolecular complexes, small organelles, and nanoparticles in solution.

  9. THE VAPOUR PRESSURES OF AQUEOUS SOLUTIONS WITH SPECIAL REFERENCE TO THE PROBLEM OF THE STATE OF WATER IN BIOLOGICAL FLUIDS.

    PubMed

    Grollman, A

    1931-05-20

    DATA FOR THE DEPRESSION OF VAPOUR PRESSURE ARE PRESENTED FOR THE FOLLOWING AQUEOUS SOLUTIONS: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl(2) (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances-LiCl and CaCl(2)-the principle of the additive nature of colligative properties is also only approximately true-except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances.

  10. Approximate bound-state solutions of the Dirac equation for the generalized yukawa potential plus the generalized tensor interaction

    NASA Astrophysics Data System (ADS)

    Ikot, Akpan N.; Maghsoodi, Elham; Hassanabadi, Hassan; Obu, Joseph A.

    2014-05-01

    In this paper, we obtain the approximate analytical bound-state solutions of the Dirac particle with the generalized Yukawa potential within the framework of spin and pseudospin symmetries for the arbitrary к state with a generalized tensor interaction. The generalized parametric Nikiforov-Uvarov method is used to obtain the energy eigenvalues and the corresponding wave functions in closed form. We also report some numerical results and present figures to show the effect of the tensor interaction.

  11. Solid solution alloy nanoparticles of immiscible Pd and Ru elements neighboring on Rh: changeover of the thermodynamic behavior for hydrogen storage and enhanced CO-oxidizing ability.

    PubMed

    Kusada, Kohei; Kobayashi, Hirokazu; Ikeda, Ryuichi; Kubota, Yoshiki; Takata, Masaki; Toh, Shoichi; Yamamoto, Tomokazu; Matsumura, Syo; Sumi, Naoya; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kitagawa, Hiroshi

    2014-02-01

    Pd(x)Ru(1-x) solid solution alloy nanoparticles were successfully synthesized over the whole composition range through a chemical reduction method, although Ru and Pd are immiscible at the atomic level in the bulk state. From the XRD measurement, it was found that the dominant structure of Pd(x)Ru(1-x) changes from fcc to hcp with increasing Ru content. The structures of Pd(x)Ru(1-x) nanoparticles in the Pd composition range of 30-70% consisted of both solid solution fcc and hcp structures, and both phases coexist in a single particle. In addition, the reaction of hydrogen with the Pd(x)Ru(1-x) nanoparticles changed from exothermic to endothermic as the Ru content increased. Furthermore, the prepared Pd(x)Ru(1-x) nanoparticles demonstrated enhanced CO-oxidizing catalytic activity; Pd0.5Ru0.5 nanoparticles exhibit the highest catalytic activity. This activity is much higher than that of the practically used CO-oxidizing catalyst Ru and that of the neighboring Rh, between Ru and Pd.

  12. Using "human state aware" robots to enhance physical human-robot interaction in a cooperative scenario.

    PubMed

    Guerrero, Carlos Rodriguez; Fraile Marinero, Juan Carlos; Turiel, Javier Perez; Muñoz, Victor

    2013-11-01

    Human motor performance, speed and variability are highly susceptible to emotional states. This paper reviews the impact of the emotions on the motor control performance, and studies the possibility of improving the perceived skill/challenge relation on a multimodal neural rehabilitation scenario, by means of a biocybernetic controller that modulates the assistance provided by a haptic controlled robot in reaction to undesirable physical and mental states. Results from psychophysiological, performance and self assessment data for closed loop experiments in contrast with their open loop counterparts, suggest that the proposed method had a positive impact on the overall challenge/skill relation leading to an enhanced physical human-robot interaction experience.

  13. Measuring a 10,000-fold enhancement of singlet molecular oxygen (1O2*) concentration on illuminated ice relative to the corresponding liquid solution

    NASA Astrophysics Data System (ADS)

    Bower, Jonathan P.; Anastasio, Cort

    2013-08-01

    Much attention has focused on the highly reactive hydroxyl radical in the oxidation of trace organic compounds on snow and ice (and subsequent release of volatile organics to the atmospheric boundary layer) but other oxidants are likely also important in this processing. Here we examine the ice chemistry of singlet molecular oxygen (1O2*), which can be significant in atmospheric water drops but has not been examined in ice or snow. To examine 1O2* on ice we illuminate laboratory ices containing Rose Bengal (RB) as the source of 1O2*, furfuryl alcohol (FFA) as the probe, and Na2SO4 to control the total solute concentration. We find that the 1O2*-mediated loss of FFA (and, thus, the 1O2* concentration) is up to 11,000 times greater on ice than in the equivalent liquid sample at the same photon flux. We attribute this large increase in the 1O2* steady-state concentration to the freeze-concentration of solutes into liquid-like regions (LLRs) in/on ice: compared to the initial solution, in the LLRs of ice the sources for 1O2* are highly concentrated, while the concentration of the dominant sink for 1O2* (i.e., water) remains largely unchanged. Similar to results expected in liquid solution, rates of FFA loss in ice depend on both the initial sensitizer concentration and temperature, providing evidence that these reactions occur in LLRs. However, we find that the enhancement in 1O2* concentrations on ice does not follow predictions from freezing-point depression, likely because experiments were conducted below the eutectic temperature for sodium sulfate, where all of the salt should have precipitated. We also explore a method for separating 1O2* and rad OH contributions to FFA oxidation in laboratory ices and show its application to two natural snow samples. We find that 1O2* concentrations in these snows are approximately 100 times higher than observed in polluted, mid-latitude fog waters, showing that the enhancement of 1O2* on ice is environmentally relevant and that

  14. Continuity of states between the cholesteric → line hexatic transition and the condensation transition in DNA solutions

    SciTech Connect

    Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian

    2014-11-05

    A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric → line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded → condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds some light on the complicated interactions between DNA molecules at high densities.

  15. Continuity of states between the cholesteric → line hexatic transition and the condensation transition in DNA solutions

    DOE PAGES

    Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian

    2014-11-05

    A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric → line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded → condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds somemore » light on the complicated interactions between DNA molecules at high densities.« less

  16. Ergodicity, configurational entropy and free energy in pigment solutions and plant photosystems: influence of excited state lifetime.

    PubMed

    Jennings, Robert C; Zucchelli, Giuseppe

    2014-01-01

    We examine ergodicity and configurational entropy for a dilute pigment solution and for a suspension of plant photosystem particles in which both ground and excited state pigments are present. It is concluded that the pigment solution, due to the extreme brevity of the excited state lifetime, is non-ergodic and the configurational entropy approaches zero. Conversely, due to the rapid energy transfer among pigments, each photosystem is ergodic and the configurational entropy is positive. This decreases the free energy of the single photosystem pigment array by a small amount. On the other hand, the suspension of photosystems is non-ergodic and the configurational entropy approaches zero. The overall configurational entropy which, in principle, includes contributions from both the single excited photosystems and the suspension which contains excited photosystems, also approaches zero. Thus the configurational entropy upon photon absorption by either a pigment solution or a suspension of photosystem particles is approximately zero.

  17. Continuity of states between the cholesteric → line hexatic transition and the condensation transition in DNA solutions

    NASA Astrophysics Data System (ADS)

    Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian

    2014-11-01

    A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric --> line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded --> condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding, together with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds some light on the complicated interactions between DNA molecules at high densities.

  18. The 4-Day School Week: A Partial Solution to Today's Energy Crisis and Declining State Funding to Education.

    ERIC Educational Resources Information Center

    Feldhausen, Thomas

    As a partial solution to the energy crisis and to solve the problem of drastically rising operating costs coupled with less state support, in 1980-81 the Liberty School District (Spangle, Washington) implemented a 4-day school week comparable to the program used by Cimarron School District #3 in New Mexico. A survey conducted in 1975 by the…

  19. Solution-processed ultrathin chemically derived graphene films as soft top contacts for solid-state molecular electronic junctions.

    PubMed

    Li, Tao; Hauptmann, Jonas Rahlf; Wei, Zhongming; Petersen, Søren; Bovet, Nicolas; Vosch, Tom; Nygård, Jesper; Hu, Wenping; Liu, Yunqi; Bjørnholm, Thomas; Nørgaard, Kasper; Laursen, Bo W

    2012-03-01

    A novel method using solution-processed ultrathin chemically derived graphene films as soft top contacts for the non-destructive fabrication of molecular junctions is demonstrated. We believe this protocol will greatly enrich the solid-state test beds for molecular electronics due to its low-cost, easy-processing and flexible nature.

  20. Oxidation of trace amounts of transplutonium elements to the tetravalent state in solutions of mineral acids and their stabilities

    SciTech Connect

    Milyukova, M.S.; Varezhkina, N.S.; Kuzovkina, E.V.; Malikov, D.A.; Myasoedov, B.F.

    1989-01-01

    The behavior of trace amounts of americium(IV) in sulfuric and nitric acid solutions as a function of the mineral acid, potassium phosphotungstate, and ammonium persulfate concentrations was investigated. The stability of americium(IV) was studied. The optimal conditions and time of oxidation of trace amounts of americium to the tetravalent state were found on the basis of the experimental data obtained.

  1. HIGH-RESOLUTION SOLUTION-STATE NMR OF UNFRACTIONATED PLANT CELL WALLS: POTENTIAL FOR BIOMASS SELECTION AND PROCESS OPTIMIZATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Detailed structural studies on the plant cell wall have traditionally been difficult. NMR is one of the preeminent structural tools, but obtaining high-resolution solution-state spectra has typically required fractionation and isolation of components of interest. With new methods for dissolution of,...

  2. Computer program VARI-QUIR 3 provides solution of steady-state, multigroup, two-dimensional neutron diffusion equations

    NASA Technical Reports Server (NTRS)

    Collier, G.

    1967-01-01

    Computer program VARI-QUIR 3 provides Gauss-Seidel type of solution with inner and outer iterations for steady-state, multigroup, two-dimensional neutron diffusion equations. The program has no restrictions on any of the input parameters such as the number of groups, regions, or materials.

  3. Technical note: Analytical drawdown solution for steady-state pumping tests in two-dimensional isotropic heterogeneous aquifers

    NASA Astrophysics Data System (ADS)

    Zech, Alraune; Attinger, Sabine

    2016-05-01

    A new method is presented which allows interpreting steady-state pumping tests in heterogeneous isotropic transmissivity fields. In contrast to mean uniform flow, pumping test drawdowns in heterogeneous media cannot be described by a single effective or equivalent value of hydraulic transmissivity. An effective description of transmissivity is required, being a function of the radial distance to the well and including the parameters of log-transmissivity: mean, variance, and correlation length. Such a model is provided by the upscaling procedure radial coarse graining, which describes the transition of near-well to far-field transmissivity effectively. Based on this approach, an analytical solution for a steady-state pumping test drawdown is deduced. The so-called effective well flow solution is derived for two cases: the ensemble mean of pumping tests and the drawdown within an individual heterogeneous transmissivity field. The analytical form of the solution allows inversely estimating the parameters of aquifer heterogeneity. For comparison with the effective well flow solution, virtual pumping tests are performed and analysed for both cases, the ensemble mean drawdown and pumping tests at individual transmissivity fields. Interpretation of ensemble mean drawdowns showed proof of the upscaling method. The effective well flow solution reproduces the drawdown for two-dimensional pumping tests in heterogeneous media in contrast to Thiem's solution for homogeneous media. Multiple pumping tests conducted at different locations within an individual transmissivity field are analysed, making use of the effective well flow solution to show that all statistical parameters of aquifer heterogeneity can be inferred under field conditions. Thus, the presented method is a promising tool with which to estimate parameters of aquifer heterogeneity, in particular variance and horizontal correlation length of log-transmissivity fields from steady-state pumping test measurements.

  4. Highly sensitive detection of proteins and bacteria in aqueous solution using surface-enhanced Raman scattering and optical fibers.

    PubMed

    Yang, Xuan; Gu, Claire; Qian, Fang; Li, Yat; Zhang, Jin Z

    2011-08-01

    We report the detection of the proteins lysozyme and cytochrome c as well as the live bacterial cells of Shewanella oneidensis MR-1 in aqueous solutions with sensitivities order(s) of magnitude higher than those previously reported. Two highly sensitive surface-enhanced Raman scattering (SERS)-based biosensors using optical fibers have been employed for such label-free macromolecule detections. The first sensor is based on a tip-coated multimode fiber (TCMMF) with a double-substrate "sandwich" structure, and a detection limit of 0.2 μg/mL is achieved in protein detections. The second sensor is based on a liquid core photonic crystal fiber (LCPCF) with a better confinement of light inside the fiber core, and a detection limit of 10(6) cells/mL is achieved for the bacteria detection. Both SERS biosensors show great potential for highly sensitive and molecule-specific detection and identification of biomolecules. PMID:21692506

  5. Power factor enhancement in solution-processed organic n-type thermoelectric materials through side chain design

    NASA Astrophysics Data System (ADS)

    Russ, Boris; Robb, Maxwell J.; Brunetti, Fulvio G.; Miller, Levi; Patel, Shrayesh; Ho, Victor; Urban, Jeffrey J.; Chabinyc, Michael L.; Hawker, Craig J.; Segalman, Rachel A.

    2014-03-01

    Building efficient organic thermoelectric architectures requires complementary p-type (hole transporting) and n-type (electron transporting) components. While several high performance hole-transporting polymers have been developed, the design of n-type organics has proven challenging, and thermoelectric studies of organic n-type systems are scarce. We investigate the properties of a series of charged perylene diimide (PDI) derivatives. Charged side chains in these materials enable both water solubility and self-doping. We show that changing the length of the alkyl spacer between the charged end groups and the PDI core dramatically improves thin film thermoelectric properties. The top derivatives in our study demonstrated the highest power factor reported for n-type solution-processed films. By complementing thermoelectric characterization of these variants with insight on the electronic and structural property changes from optical spectroscopy, EPR, and GIWAXS experiments, our findings shape a promising molecular design strategy for future enhancements in thermoelectric performance.

  6. Effect of Lanthanide Ions on Dynamic Nuclear Polarization Enhancement and Liquid State T1 Relaxation

    PubMed Central

    Gordon, Jeremy; Fain, Sean B.; Rowland, Ian J

    2012-01-01

    In the dynamic nuclear polarization process, microwave irradiation facilitates exchange of polarization from a radical’s unpaired electron to nuclear spins at cryogenic temperatures, increasing polarization by >10000. Doping samples with Gd3+ ions further increases the achievable solid-state polarization. However, upon dissolution, paramagnetic lanthanide metals can be potent relaxation agents, decreasing liquid-state polarization. Here, the effects of lanthanide metals on the solid and liquid-state magnetic properties of [1-13C]pyruvate are studied. The results show that in addition to gadolinium, holmium not only increases the achievable polarization but also the rate of polarization. Liquid-state relaxation studies found that unlike gadolinium, holmium minimally affects T1. Additionally, results reveal that linear contrast agents dissociate in pyruvic acid, greatly reducing liquid-state T1. While macrocyclic agents do not readily dissociate, they yield lower solid-state polarization. Results indicate that polarization with free lanthanides and subsequent chelation during dissolution produces the highest polarization enhancement while minimizing liquid-state relaxation. PMID:22367680

  7. Part 2: A field study of enhanced remediation of Toluene in the vadose zone using a nutrient solution

    USGS Publications Warehouse

    Tindall, J.A.; Weeks, E.P.; Friedel, M.

    2005-01-01

    The objective of this study was to test the effectiveness of a nitrate-rich nutrient solution and hydrogen peroxide (H2O2) to enhance in-situ microbial remediation of toluene in the unsaturated zone. Three sand-filled plots were tested in three phases (each phase lasting approximately 2 weeks). During the control phase, toluene was applied uniformly via sprinkler irrigation. Passive remediation was allowed to occur during this phase. A modified Hoagland nutrient solution, concentrated in 150 L of water, was tested during the second phase. The final phase involved addition of 230 moles of H2O2 in 150 L of water to increase the available oxygen needed for aerobic biodegradation. During the first phase, measured toluene concentrations in soil gas were reduced from 120 ppm to 25 ppm in 14 days. After the addition of nutrients during the second phase, concentrations were reduced from 90 ppm to about 8 ppm within 14 days, and for the third phase (H 2O2), toluene concentrations were about 1 ppm after only 5 days. Initial results suggest that this method could be an effective means of remediating a contaminated site, directly after a BTEX spill, without the intrusiveness and high cost of other abatement technologies such as bioventing or soil-vapor extraction. However, further tests need to be completed to determine the effect of each of the BTEX components. ?? Springer 2005.

  8. An enhanced security solution for electronic medical records based on AES hybrid technique with SOAP/XML and SHA-1.

    PubMed

    Kiah, M L Mat; Nabi, Mohamed S; Zaidan, B B; Zaidan, A A

    2013-10-01

    This study aims to provide security solutions for implementing electronic medical records (EMRs). E-Health organizations could utilize the proposed method and implement recommended solutions in medical/health systems. Majority of the required security features of EMRs were noted. The methods used were tested against each of these security features. In implementing the system, the combination that satisfied all of the security features of EMRs was selected. Secure implementation and management of EMRs facilitate the safeguarding of the confidentiality, integrity, and availability of e-health organization systems. Health practitioners, patients, and visitors can use the information system facilities safely and with confidence anytime and anywhere. After critically reviewing security and data transmission methods, a new hybrid method was proposed to be implemented on EMR systems. This method will enhance the robustness, security, and integration of EMR systems. The hybrid of simple object access protocol/extensible markup language (XML) with advanced encryption standard and secure hash algorithm version 1 has achieved the security requirements of an EMR system with the capability of integrating with other systems through the design of XML messages.

  9. Enhanced Remediation of Toluene in the Vadose Zone via a Nitrate-Rich Nutrient Solution: Field Study

    NASA Astrophysics Data System (ADS)

    Tindall, J. A.; Friedel, M. J.

    2003-12-01

    The objective of this study was to test the effectiveness of nitrate-rich nutrient solutions and hydrogen peroxide (H202) to enhance in-situ microbial remediation of toluene. Three sand filled plots (2 m2 surface area and 1.5 meters deep) were tested in three phases (each phase lasting approximately 2 weeks). During each phase, toluene (21.6 mol as an emulsion in 50L of water) was applied uniformly via sprinkler irrigation. Passive remediation was allowed to occur during the first (control) phase. A nutrient solution (modified Hoagland), concentrated in 40L of water, was tested during the second phase. The final phase involved addition of 230 moles of H202 in 50L of water to increase the available oxygen needed for aerobic biodegradation. During the first phase, toluene concentrations in soil gas were reduced from 120 ppm to 25 ppm in 14 days. After the addition of nutrients during the second phase, concentrations were reduced from 90 ppm to about 8 ppm within 14 days, and for the third phase (H202), toluene concentrations were about 1 ppm after only five days. Initial results suggest that this method could be an effective means of remediating a contaminated site, directly after a BTEX spill, without the intrusiveness and high cost of other abatement technologies such as bioventing and soil vapor extraction. However, further tests need to be completed to determine the effect of each of the BTEX components.

  10. Enhanced aqueous solubility of polycyclic aromatic hydrocarbons by green diester-linked cationic gemini surfactants and their binary solutions

    NASA Astrophysics Data System (ADS)

    Panda, Manorama; Fatma, Nazish; Kabir-ud-Din

    2016-07-01

    Three homologues of a novel biodegradable diester-linked cationic gemini surfactant series, CmH2m+1 (CH3)2N+(CH2COOCH2)2N+(CH3)2CmH2m+1.2Cl- (m-E2-m; m = 12, 14, 16), were used for investigation of the solubilization of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, anthracene and pyrene in single as well as binary surfactant solutions. Physicochemical parameters of the pure/mixed systems were derived by conductivity and surface tension measurements. Dissolution capacity of the equimolar binary surfactant solutions towards the PAHs was studied from the molar solubilization ratio (MSR), micelle-water partition coefficient (Km) and free energy of solubilization (ΔGs0) of the solubilizates. Influence of hydrophobic chain length of the dimeric surfactants on solubilization was characterized. Aqueous solubility of the PAHs was enhanced linearly with concentration of the surfactant in all the pure and mixed gemini-gemini surfactant systems.

  11. An enhanced security solution for electronic medical records based on AES hybrid technique with SOAP/XML and SHA-1.

    PubMed

    Kiah, M L Mat; Nabi, Mohamed S; Zaidan, B B; Zaidan, A A

    2013-10-01

    This study aims to provide security solutions for implementing electronic medical records (EMRs). E-Health organizations could utilize the proposed method and implement recommended solutions in medical/health systems. Majority of the required security features of EMRs were noted. The methods used were tested against each of these security features. In implementing the system, the combination that satisfied all of the security features of EMRs was selected. Secure implementation and management of EMRs facilitate the safeguarding of the confidentiality, integrity, and availability of e-health organization systems. Health practitioners, patients, and visitors can use the information system facilities safely and with confidence anytime and anywhere. After critically reviewing security and data transmission methods, a new hybrid method was proposed to be implemented on EMR systems. This method will enhance the robustness, security, and integration of EMR systems. The hybrid of simple object access protocol/extensible markup language (XML) with advanced encryption standard and secure hash algorithm version 1 has achieved the security requirements of an EMR system with the capability of integrating with other systems through the design of XML messages. PMID:24037086

  12. Enhanced pervaporation performance of multi-layer PDMS/PVDF composite membrane for ethanol recovery from aqueous solution.

    PubMed

    Zhan, Xia; Li, Jiding; Huang, Junqi; Chen, Cuixian

    2010-01-01

    Multi-layer PDMS/PVDF composite membrane with an alternative PDMS/PVDF/non-woven-fiber/PVDF/PDMS configuration was prepared in this paper. The porous PVDF substrate was obtained by casting PVDF solution on both sides of non-woven fiber with immersion precipitation phase inversion method. Polydimethylsiloxane (PDMS) was then cured by phenyltrimethoxylsilane (PTMOS) and coated onto the surface of porous PVDF substrate one layer by the other to obtain multi-layer PDMS/PVDF composite membrane. The multi-layer composite membrane was used for ethanol recovery from aqueous solution by pervaporation, and exhibited enhanced separation performance compared with one side PDMS/PVDF composite membranes, especially in the low ethanol concentration range. The maximum separation factor of multi-layer PDMS/PVDF composite membrane was obtained at 60 degrees C, and the total flux increased exponentially along with the increase of temperature. The composite membrane gave the best pervaporation performance with a separation factor of 15, permeation rate of 450 g/m(2)h with a 5 wt.% ethanol concentration at 60 degrees C.

  13. Aluminum-doped ceria-zirconia solid solutions with enhanced thermal stability and high oxygen storage capacity

    PubMed Central

    2012-01-01

    A facile solvothermal method to synthesize aluminum-doped ceria-zirconia (Ce0.5Zr0.5-xAlxO2-x/2, x = 0.1 to 0.4) solid solutions was carried out using Ce(NH4)2(NO3)6, Zr(NO3)3·2H2O Al(NO3)3·9H2O, and NH4OH as the starting materials at 200°C for 24 h. The obtained solid solutions from the solvothermal reaction were calcined at 1,000°C for 20 h in air atmosphere to evaluate the thermal stability. The synthesized Ce0.5Zr0.3Al0.2O1.9 particle was characterized for the oxygen storage capacity (OSC) in automotive catalysis. For the characterization, X-ray diffraction, transmission electron microscopy, and the Brunauer-Emmet-Teller (BET) technique were employed. The OSC values of all samples were measured at 600°C using thermogravimetric-differential thermal analysis. Ce0.5Zr0.3Al0.2O1.9 solid solutions calcined at 1,000°C for 20 h with a BET surface area of 18 m2 g−1 exhibited a considerably high OSC of 427 μmol-O g−1 and good OSC performance stability. The same synthesis route was employed for the preparation of the CeO2 and Ce0.5Zr0.5O2. The incorporation of aluminum ion in the lattice of ceria-based catalyst greatly enhanced the thermal stability and OSC. PMID:23025588

  14. The solution, solid state stability and kinetic investigation in degradation studies of lercanidipine: study of excipients compatibility of lercanidipine.

    PubMed

    Parmar, Nitin; Amin, Saima; Singla, Neelam; Kohli, Kanchan

    2012-01-01

    The objectives of this research were to evaluate the stability of lercanidipine in solution state and solid state and explore the compatibility of drug with oils, surfactants and cosurfactants as excipients. The effect of pH on the degradation in solution state was studied through pH-rate profile of lercanidipine in constant ionic strength buffer solutions in pH range 1-8 which gives the pH of maximum stability. Powdered lercanidipine was stored under 40°C/0%~75% relative humidities (RH) or 0% RH/5~50°C to study the influence of RH and temperature on the stability of lercanidipine in solid state. Binary mixtures of lercanidipine and different excipients were stored at 40°C/75% RH, 40°C and at room temperature for excipient compatibility evaluation. The degradation of lercanidipine at different pH appears to fit a typical first-order reaction, but in solid state, it does not fit any obvious reaction model. Moisture content and temperature both play important roles affecting the degradation rate. Lercanidipine exhibits good compatibility with surfactants, cosurfactants and oils as excipients under stressed conditions of different storage temperature in a 3-week screening study. Moreover, the proposed high-performance liquid chromatography method was utilized to investigate the kinetics of the acidic and alkaline degradation processes of lercanidipine at different temperatures.

  15. Solid state and solution 43Ca NMR of calcium peroxides involved in the disproportionation of hydrogen peroxide by calcium hydroxide.

    PubMed

    Trokiner, Arlette; Bessière, Aurélie; Thouvenot, René; Hau, Damien; Marko, Jean; Nardello, Véronique; Pierlot, Christel; Aubry, Jean-Marie

    2004-06-01

    In order to get some insight into the mechanism of the disproportionation of hydrogen peroxide catalyzed by calcium hydroxide, 43Ca NMR spectra of enriched samples of calcium peroxides and of their precursors have been studied in both solution and solid state. This study demonstrates that no well-defined peroxidized calcium species are formed in solution, showing that the catalytic role of calcium is likely restricted to the solid state. Most of the calcium compounds that could be involved in the catalytic process have been investigated with solid state NMR. The shift and quadrupolar parameters of Ca(OH)2, CaO2.8H2O and CaO2.2H2O2 are reported for the first time. These parameters are different enough to allow the quantitative analysis of a complex mixture of these compounds by NMR.

  16. Studies of the photophysics of highly fluorescent Red Mega 480 laser dye in solutions: Steady state spectroscopy.

    PubMed

    Tangod, V B; Mastiholi, B M; Raikar, Prasad; Kulkarni, S G; Raikar, U S

    2015-09-01

    The absorption and fluorescence spectra of highly fluorescent industrially useful medium sized Red Mega 480 dye have been studied in various solvents at 298 K. The solute photophysical behavior depends strongly on the solute-solvent interactions. In order to understand the effect of inter molecular interactions on spectral behaviors of the dye in different solvents extent of this behavior can be analyzed by linear solvation energy relationships. In addition, ground and excited state dipole moments were evaluated by various methods. It is observed that excited state dipole moment (μe) is larger than the ground state (μg), absorption spectra show a bathochromic shift with increasing polarity indicating that transition involved is π→π(∗) and Onsager cavity radius is determined by atomic increment method.

  17. Enhanced Removal of Hexavalent Chromium in the Presence of H2O2 in Frozen Aqueous Solutions.

    PubMed

    Kim, Kitae; Kim, Jaesung; Bokare, Alok D; Choi, Wonyong; Yoon, Ho-Il; Kim, Jungwon

    2015-09-15

    The reductive transformation of Cr(VI) to Cr(III) by H2O2 in ice was compared with that in water. The reduction of Cr(VI) was significant at -20 °C (ice), whereas the reduction efficiency was very low at 25 °C (water). This enhanced reduction of Cr(VI) in ice was observed over a wide range of H2O2 concentration (20-1000 μM), pH (3-11), and freezing temperature (-10 to -30 °C). The observed molar ratio of consumed [H2O2] to reduced [Cr(VI)] in ice was in close agreement with the theoretical (stoichiometric) molar ratio (1.5) for H2O2-mediated Cr(VI) reduction through proton-coupled electron transfer (PCET). The synergistic increase in Cr(VI) reduction in water by increasing the H2O2 and proton concentrations confirms that the freeze concentration of both H2O2 and protons in the liquid brine is primarily responsible for the enhanced Cr(VI) reduction in ice. In comparison, the one-electron reduction of Cr(VI) to Cr(V) and subsequent reoxidation of Cr(V) to Cr(VI) is the major reaction mechanism in aqueous solution. The reduction efficiency of Cr(VI) by H2O2 in the frozen aqueous electroplating wastewater was similar to that in the frozen aqueous deionized water, which verifies the enhanced reduction of Cr(VI) by freezing in real Cr(VI)-contaminated aquatic systems.

  18. Monte Carlo simulation and equation of state for flexible charged hard-sphere chain fluids: Polyampholyte and polyelectrolyte solutions

    SciTech Connect

    Jiang, Hao; Adidharma, Hertanto

    2014-11-07

    The thermodynamic modeling of flexible charged hard-sphere chains representing polyampholyte or polyelectrolyte molecules in solution is considered. The excess Helmholtz energy and osmotic coefficients of solutions containing short polyampholyte and the osmotic coefficients of solutions containing short polyelectrolytes are determined by performing canonical and isobaric-isothermal Monte Carlo simulations. A new equation of state based on the thermodynamic perturbation theory is also proposed for flexible charged hard-sphere chains. For the modeling of such chains, the use of solely the structure information of monomer fluid for calculating the chain contribution is found to be insufficient and more detailed structure information must therefore be considered. Two approaches, i.e., the dimer and dimer-monomer approaches, are explored to obtain the contribution of the chain formation to the Helmholtz energy. By comparing with the simulation results, the equation of state with either the dimer or dimer-monomer approach accurately predicts the excess Helmholtz energy and osmotic coefficients of polyampholyte and polyelectrolyte solutions except at very low density. It also well captures the effect of temperature on the thermodynamic properties of these solutions.

  19. Structural studies of bean pod mottle virus, capsid, and RNA in crystal and solution states by laser Raman spectroscopy

    SciTech Connect

    Li, Tiansheng; Thomas, G.J. Jr. ); Chen, Zhongguo; Johnson, J.E. )

    1990-05-29

    Structures of protein and RNA components of bean pod mottle virus (BPMV) have been investigated by use of laser Raman spectroscopy. Raman spectra were collected from both aqueous solutions and single crystals of BPMV capsids (top component) and virions (middle and bottom components, which package, respectively, small and large RNA molecules). Analysis of the data permits the assignment of conformation-sensitive Raman bands to viral protein and RNA constituents and observation of structural similarities and differences between solution and crystalline states of BPMV components. The Raman results show that the protein subunits of the empty capsid contain between 45% and 55% {beta}-strand and {beta}-turn secondary structure, in agreement with the recently determined X-ray crystal structure, and that this total {beta}-strand content undergoes a small increase with packaging of RNA. A comparison of Raman spectra of crystal and solution states of the BPMV middle component reveals only minor structural differences between the two, and these are restricted almost exclusively to Raman bands of RNA in the region of assigned phosphodiester conformation markers. Although in both the crystal and solution only C3{prime} endo/anti nucleosides are detected, the crystal exhibits a weaker 813-cm{sup {minus}1} band and strong 870-cm{sup {minus}1} band, which suggests that {approximately}8% of the nucleotides have O-P-O torsions configured differently in the crystal from that in the solution.

  20. Method of Enhancing On-Board State Estimation Using Communication Signals

    NASA Technical Reports Server (NTRS)

    Anzalone, Evan J. (Inventor); Chuang, Jason C. H. (Inventor)

    2015-01-01

    A method of enhancing on-board state estimation for a spacecraft utilizes a network of assets to include planetary-based assets and space-based assets. Communication signals transmitted from each of the assets into space are defined by a common protocol. Data is embedded in each communication signal transmitted by the assets. The data includes a time-of-transmission for a corresponding one of the communication signals and a position of a corresponding one of the assets at the time-of-transmission. A spacecraft is equipped to receive the communication signals, has a clock synchronized to the space-wide time reference frame, and has a processor programmed to generate state estimates of the spacecraft. Using its processor, the spacecraft determines a one-dimensional range from itself to at least one of the assets and then updates its state estimates using each one-dimensional range.

  1. Enhanced visibility of two-mode thermal squeezed states via degenerate parametric amplification and resonance

    NASA Astrophysics Data System (ADS)

    Mahboob, I.; Okamoto, H.; Yamaguchi, H.

    2016-08-01

    Two-mode squeezed states, generated via non-degenerate parametric down-conversion, are invariably revealed via their entangled vacuum or correlated thermal fluctuations. Here, two-mode thermal squeezed states, generated in an electromechanical system, are made bright by means of degenerate parametric amplification of their constituent modes to the point where they are almost perfect, even when seeded from low intensity non-degenerate parametric down-conversion. More dramatically, activating the degenerate parametric resonances of the underlying modes yields perfect correlations which can be resolved via the coordinated switching of their phase bi-stable vibrations, without recourse to monitoring their thermal fluctuations. This ability to enhance the two-mode squeezed states and to decipher them without needing to observe their intrinsic noise is supported by both analytical and numerical modelling and it suggests that the technical constraints to making this phenomenon more widely available can be dramatically relaxed.

  2. Existence and stability of periodic solution of a Lotka-Volterra predator-prey model with state dependent impulsive effects

    NASA Astrophysics Data System (ADS)

    Nie, Linfei; Peng, Jigen; Teng, Zhidong; Hu, Lin

    2009-02-01

    According to biological and chemical control strategy for pest, we investigate the dynamic behavior of a Lotka-Volterra predator-prey state-dependent impulsive system by releasing natural enemies and spraying pesticide at different thresholds. By using Poincaré map and the properties of the Lambert W function, we prove that the sufficient conditions for the existence and stability of semi-trivial solution and positive periodic solution. Numerical simulations are carried out to illustrate the feasibility of our main results.

  3. Identification of standing fronts in steady state fluid flows: exact and approximate solutions for propagating MHD modes

    NASA Astrophysics Data System (ADS)

    Pantellini, Filippo; Griton, Léa

    2016-10-01

    The spatial structure of a steady state plasma flow is shaped by the standing modes with local phase velocity exactly opposite to the flow velocity. The general procedure of finding the wave vectors of all possible standing MHD modes in any given point of a stationary flow requires numerically solving an algebraic equation. We present the graphical procedure (already mentioned by some authors in the 1960's) along with the exact solution for the Alfvén mode and approximate analytic solutions for both fast and slow modes. The technique can be used to identify MHD modes in space and laboratory plasmas as well as in numerical simulations.

  4. Molecular structures and protonation state of 2-Mercaptopyridine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Eckert, S.; Miedema, P. S.; Quevedo, W.; O'Cinneide, B.; Fondell, M.; Beye, M.; Pietzsch, A.; Ross, M.; Khalil, M.; Föhlisch, A.

    2016-03-01

    The speciation of 2-Mercaptopyridine in aqueous solution has been investigated with nitrogen 1s Near Edge X-ray Absorption Fine Structure spectroscopy and time dependent Density Functional Theory. The prevalence of distinct species as a function of the solvent basicity is established. No indications of dimerization towards high concentrations are found. The determination of different molecular structures of 2-Mercaptopyridine in aqueous solution is put into the context of proton-transfer in keto-enol and thione-thiol tautomerisms.

  5. A closed-form solution for steady-state coupled phloem/xylem flow using the Lambert-W function.

    PubMed

    Hall, A J; Minchin, P E H

    2013-12-01

    A closed-form solution for steady-state coupled phloem/xylem flow is presented. This incorporates the basic Münch flow model of phloem transport, the cohesion model of xylem flow, and local variation in the xylem water potential and lateral water flow along the transport pathway. Use of the Lambert-W function allows this solution to be obtained under much more general and realistic conditions than has previously been possible. Variation in phloem resistance (i.e. viscosity) with solute concentration, and deviations from the Van't Hoff expression for osmotic potential are included. It is shown that the model predictions match those of the equilibrium solution of a numerical time-dependent model based upon the same mechanistic assumptions. The effect of xylem flow upon phloem flow can readily be calculated, which has not been possible in any previous analytical model. It is also shown how this new analytical solution can handle multiple sources and sinks within a complex architecture, and can describe competition between sinks. The model provides new insights into Münch flow by explicitly including interactions with xylem flow and water potential in the closed-form solution, and is expected to be useful as a component part of larger numerical models of entire plants.

  6. Surface-enhanced Raman spectroscopy in the structural studies of biomolecules: the state of the art

    NASA Astrophysics Data System (ADS)

    Nabiev, Igor R.; Sokolov, Konstantin V.; Efremov, R. G.; Chumanov, George D.

    1991-05-01

    It has been recently demonstrated'3 that very large (in some cases up to iOn) enhancement of Raman crosssection for molecules in the close vicinity of a metal surface results from superposition of two main mechanisms: electromagnetic and so-called molecular (or "chemical"). Enhancement of the local electromagnetic field near a "rough" metal surface induces the electromagnetic mechanism, while the "molecular" mechanism is connected with the appearance of new excited states for the molecule/metal complexes in the process of chemisorption. The techniques of surface-enhanced Raman (SER) and surface-enhanced resonance Raman (SERR) spectroscopy are based on these mechanisms and widely used in investigations ofbiological molecules.27 The three main questions of applicability of SERS and SERRS for resolving sophisticated problems in molecular biology, bioorganic and physical chemistry are the following: (i) What are the molecular mechanisms of interaction of the biomolecules with a metal surface in the experimental conditions typical of SERS appearance and is it possible to take measurements while preserving the native conformation of the molecule? (ii) What is the exact relationship between the Raman cross-section enhancement and the distance between the metal and the molecule? Is the mechanism for enhancement short-range or long-range and is it be possible to detect all normal vibrations of macromolecules or only vibrations of groups which directly contact the surface? (iii) What are the lowest concentrations for the detection of SER spectra of biomolecules in different experimental systems (electrodes, hydrosols, surfaces with regular roughness)? Is it possible to detect high-quality SER spectra of subpicogram amounts of different classes of biomolecules for successful competition with the traditional techniques in biotechnology and genetic engineering? This paper deals with applications of SERS to the study of membrane proteins and nucleic acids.

  7. Some Classes of Imperfect Information Finite State-Space Stochastic Games with Finite-Dimensional Solutions

    SciTech Connect

    McEneaney, William M.

    2004-08-15

    Stochastic games under imperfect information are typically computationally intractable even in the discrete-time/discrete-state case considered here. We consider a problem where one player has perfect information.A function of a conditional probability distribution is proposed as an information state.In the problem form here, the payoff is only a function of the terminal state of the system,and the initial information state is either linear ora sum of max-plus delta functions.When the initial information state belongs to these classes, its propagation is finite-dimensional.The state feedback value function is also finite-dimensional,and obtained via dynamic programming,but has a nonstandard form due to the necessity of an expanded state variable.Under a saddle point assumption,Certainty Equivalence is obtained and the proposed function is indeed an information state.

  8. A Holistic, rapid-deployment, solution for safe used nuclear fuel management in the United States of America

    SciTech Connect

    Eriksson, L.G.

    2007-07-01

    Recent political initiatives and increased willingness in the United States of America (U.S. or USA) to consider federal storage and recycling of used nuclear fuel (UNF), augmented by expressed private interest in developing 31 new nuclear power plants, strongly suggest that the U.S. is on the brink of a nuclear-energy renaissance. Unfortunately, the related UNF-management and -disposition research, technology, and facility developments have been virtually dormant for 25 years. Fortunately, other countries have pursued safe UNF-management and -disposition solutions during this period that the U.S. now can take advantage of to develop the required UNF-management technologies and facilities in a timely and cost-effective manner. The following criteria/concepts for the timely and cost-effective development of safe and secure nuclear facilities were applied to current and planned UNF-management in the U.S. to formulate a potential, holistic, 'rapid-deployment' UNF-management solution at the Nevada Test Site (NTS), referred to as the Nevada National Nuclear Fuel Management Center (3NFMC): - Locate pending UNF-storage and -recycling facilities on the NTS in the vicinity of the Nation's candidate deep geological disposal system (repository) for UNF and other high level radioactive waste (HLW) at the Yucca Mountain (YM) site; - Locate all main UNF-management facilities underground; and - Use best-available technology to site, design, and construct the pending facilities. Three main challenges to the timely and cost-effective development of the 3NFMC are: (1) Statutory restrictions preventing the UNF-storage and -disposal facilities from being co-located and co-developed by federal and civilian/private parties; (2) Long-standing, scientific, local-political, key-Congressional, and national-ideological opposition to the YM UNF/HLW repository; and (3) The discouraging track record, and the related lack of trust in, and credibility of the organization currently responsible for

  9. Structural Characterization of Humic Materials Using ^13C NMR Techniques: A Comparison of Solution- and Solid-State Methods

    NASA Astrophysics Data System (ADS)

    Clewett, Catherine; Alam, Todd; Osantowski, Eric; Pullin, Michael

    2011-10-01

    The analysis of the carbon type distribution and chemical structure of natural organic matter (NOM) by ^13C NMR spectroscopy is an important technique for understanding its origins and reactivity. While prior work has used solution-state NMR techniques, solid-state NMR has the potential to provide this information using less instrument time and sample manipulation, while providing an array of advanced filtering techniques. Analyses of four isolated humic materials with ^13C solid-state magic angle spinning (MAS) NMR techniques are described, including three commercially available samples and one fulvic acid sample isolated from the Rio Grande in New Mexico. This study demonstrates the utility of solid-state ^13C NMR for aquatic NOM structural characterization, comparing these results to the existing solution-state determinations. The solid-state ^13C MAS NMR results are used to determine % carbon distribution, estimates of elemental composition (%C, %H, %(O+N)), aromatic fraction (fa), nonprotonated aromatic fraction (faN), an estimate of aromatic cluster size, and ratio of sp^2 to sp^3 carbons. A Gaussian deconvolution method is introduced that allows for a detailed analysis of carbon type.

  10. Wireless Sensor Network Security Enhancement Using Directional Antennas: State of the Art and Research Challenges.

    PubMed

    Curiac, Daniel-Ioan

    2016-04-07

    Being often deployed in remote or hostile environments, wireless sensor networks are vulnerable to various types of security attacks. A possible solution to reduce the security risks is to use directional antennas instead of omnidirectional ones or in conjunction with them. Due to their increased complexity, higher costs and larger sizes, directional antennas are not traditionally used in wireless sensor networks, but recent technology trends may support this method. This paper surveys existing state of the art approaches in the field, offering a broad perspective of the future use of directional antennas in mitigating security risks, together with new challenges and open research issues.

  11. Wireless Sensor Network Security Enhancement Using Directional Antennas: State of the Art and Research Challenges

    PubMed Central

    Curiac, Daniel-Ioan

    2016-01-01

    Being often deployed in remote or hostile environments, wireless sensor networks are vulnerable to various types of security attacks. A possible solution to reduce the security risks is to use directional antennas instead of omnidirectional ones or in conjunction with them. Due to their increased complexity, higher costs and larger sizes, directional antennas are not traditionally used in wireless sensor networks, but recent technology trends may support this method. This paper surveys existing state of the art approaches in the field, offering a broad perspective of the future use of directional antennas in mitigating security risks, together with new challenges and open research issues. PMID:27070601

  12. Wireless Sensor Network Security Enhancement Using Directional Antennas: State of the Art and Research Challenges.

    PubMed

    Curiac, Daniel-Ioan

    2016-01-01

    Being often deployed in remote or hostile environments, wireless sensor networks are vulnerable to various types of security attacks. A possible solution to reduce the security risks is to use directional antennas instead of omnidirectional ones or in conjunction with them. Due to their increased complexity, higher costs and larger sizes, directional antennas are not traditionally used in wireless sensor networks, but recent technology trends may support this method. This paper surveys existing state of the art approaches in the field, offering a broad perspective of the future use of directional antennas in mitigating security risks, together with new challenges and open research issues. PMID:27070601

  13. Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with α-hydroxyisobutyric acid.

    PubMed

    Chen, Xiao-Yan; Goff, George S; Ewing, William C; Scott, Brian L; Runde, Wolfgang

    2012-12-17

    Despite the wide range of applications of α-hydroxyisobutyric acid (HIBA) in biochemical processes, pharmaceutical formulations, and group and elemental separations of lanthanides and actinides, the structures and geometries of lanthanide-HIBA complexes are still not well understood. We reacted HIBA with lanthanides in aqueous solution at pH = 5 and synthesized 14 lanthanide-HIBA complexes of the formula [Ln(HIBA)(2)(H(2)O)(2)](NO(3))·H(2)O (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14)), isolating single crystals (1-7, 10, and 11) and powders (8, 9, and 12-14). Both single-crystal and powder X-ray diffraction studies reveal a two-dimensional extended structure across the entire lanthanide series. The environment around the eight-coordinated Ln(III) atom is best described as a distorted dodecahedron, where HIBA acts as a monoanionic tridentate ligand with one carboxylato oxygen atom and one hydroxyl oxygen atom chelating to one Ln(III) center. The carboxylato oxygen atom from a second HIBA ligand bridges to a neighboring Ln(III) atom to form a two-dimensional extended structure. While the coordination mode for HIBA is identical across the lanthanide series, three different structure types are found for La, Ce-Ho, and Er-Lu. Solution characterization using (13)C NMR further confirmed a single solution complex under the crystallization conditions. Raman and UV-vis-NIR absorbance and diffuse reflectance spectra of HIBA-Ln(III) complexes were also measured.

  14. Towards high concentration enhancement of microfluidic temperature gradient focusing of sample solutes using combined AC and DC field induced Joule heating.

    PubMed

    Ge, Zhengwei; Wang, Wei; Yang, Chun

    2011-04-01

    It is challenging to continuously concentrate sample solutes in microfluidic channels. We present an improved electrokinetic technique for enhancing microfluidic temperature gradient focusing (TGF) of sample solutes using combined AC and DC field induced Joule heating effects. The introduction of an AC electric field component services dual functions: one is to produce Joule heat for generating temperature gradient; the other is to suppress electroosmotic flow. Consequently the required DC voltages for achieving sample concentration by Joule heating induced TGF are reduced, thereby leading to smaller electroosmotic flow (EOF) and thus backpressure effects. As a demonstration, the proposed technique can lead to concentration enhancement of sample solutes of more than 2500-fold, which is much higher than the existing literature reported microfluidic concentration enhancement by utilizing the Joule heating induced TGF technique. PMID:21331425

  15. Time- and energy-efficient solution combustion synthesis of binary metal tungstate nanoparticles with enhanced photocatalytic activity.

    PubMed

    Thomas, Abegayl; Janáky, Csaba; Samu, Gergely F; Huda, Muhammad N; Sarker, Pranab; Liu, J Ping; van Nguyen, Vuong; Wang, Evelyn H; Schug, Kevin A; Rajeshwar, Krishnan

    2015-05-22

    In the search for stable and efficient photocatalysts beyond TiO2 , the tungsten-based oxide semiconductors silver tungstate (Ag2 WO4 ), copper tungstate (CuWO4 ), and zinc tungstate (ZnWO4 ) were prepared using solution combustion synthesis (SCS). The tungsten precursor's influence on the product was of particular relevance to this study, and the most significant effects are highlighted. Each sample's photocatalytic activity towards methyl orange degradation was studied and benchmarked against their respective commercial oxide sample obtained by solid-state ceramic synthesis. Based on the results herein, we conclude that SCS is a time- and energy-efficient method to synthesize crystalline binary tungstate nanomaterials even without additional excessive heat treatment. As many of these photocatalysts possess excellent photocatalytic activity, the discussed synthetic strategy may open sustainable materials chemistry avenues to solar energy conversion and environmental remediation.

  16. Classical states of an electric dipole in an external magnetic field: Complete solution for the center of mass and trapped states

    SciTech Connect

    Atenas, Boris; Pino, Luis A. del; Curilef, Sergio

    2014-11-15

    We study the classical behavior of an electric dipole in the presence of a uniform magnetic field. Using the Lagrangian formulation, we obtain the equations of motion, whose solutions are represented in terms of Jacobi functions. We also identify two constants of motion, namely, the energy E and a pseudomomentumC{sup →}. We obtain a relation between the constants that allows us to suggest the existence of a type of bound states without turning points, which are called trapped states. These results are consistent with and complementary to previous results. - Highlights: • Bound states without turning points. • Lagrangian Formulation for an electric dipole in a magnetic field. • Motion of the center of mass and trapped states. • Constants of motion: pseudomomentum and energy.

  17. On enhanced corrections from quasi-degenerate states to heavy quarkonium observables

    NASA Astrophysics Data System (ADS)

    Kiyo, Y.; Mishima, G.; Sumino, Y.

    2016-10-01

    It is well known that in perturbation theory existence of quasi-degenerate states can rearrange the order counting. For a heavy quarkonium system, naively, enhanced effects (l-changing mixing effects) could contribute already to the first-order and third-order corrections to the wave function and the energy level, respectively, in expansion in αs. We present a formulation and note that the corresponding (lowest-order) corrections vanish due to absence of the relevant off-diagonal matrix elements. As a result, in the quarkonium energy level and leptonic decay width, the enhanced effects are expected to appear, respectively, in the fifth- and fourth-order corrections and beyond.

  18. Classical states of an electric dipole in an external magnetic field: Complete solution for the center of mass and trapped states

    NASA Astrophysics Data System (ADS)

    Atenas, Boris; del Pino, Luis A.; Curilef, Sergio

    2014-11-01

    We study the classical behavior of an electric dipole in the presence of a uniform magnetic field. Using the Lagrangian formulation, we obtain the equations of motion, whose solutions are represented in terms of Jacobi functions. We also identify two constants of motion, namely, the energy E and a pseudomomentum C →. We obtain a relation between the constants that allows us to suggest the existence of a type of bound states without turning points, which are called trapped states. These results are consistent with and complementary to previous results.

  19. Resonance-enhanced multiphoton ionization of CH₂Br₂: Rydberg states, photofragmentation, and CH spectra.

    PubMed

    Long, Jingming; Wang, Huasheng; Kvaran, Ágúst

    2014-03-13

    Mass-resolved (2 + n) resonance-enhanced multiphoton ionization (REMPI) spectra of CH2Br2 in the two-photon resonance excitation region from 71 200 to 82 300 cm(-1) were recorded and analyzed. Spectral structures allowed characterization of new molecular Rydberg states. C*((1)D2) was found to be an important intermediate in the photodissociation processes. A broad spectral feature peaking at about 80 663 cm(-1) in the C(+) spectrum and frequently seen in related studies is reinterpreted and associated with switching between three- and two-photon ionization of C*((1)D2). Analysis of band structures due to transitions from the A(2)Δ state of CH* that were seen in the CH(+) and C(+) REMPI spectra allowed characterization of three electronic states of CH, assigned as E(2)Π, D(2)Π, and F(2)Σ(+), which clarifies a long-term puzzle concerning the energetics of the CH radical. Predissociation of the E, D, and F states to form C*((1)D2) occurs. Bromine atomic lines were observed and are believed to be associated with bromine atom formation via predissociation of CH2Br2 Rydberg states.

  20. Collagen functionalized with unsaturated cyclic anhydrides-interactions in solution and solid state.

    PubMed

    Potorac, S; Popa, M; Picton, L; Dulong, V; Verestiuc, L; Le Cerf, D

    2014-03-01

    Maleic anhydride (CMA) and itaconic anhydride modified collagen (CITA) were prepared as precursors for production of interpenetrated polymer networks (IPN). Calculated values for Huggins coefficient in aqueous diluted and semi-diluted solutions of modified collagen indicated a slightly tendency of aggregation for itaconic anhydride-modified collagen. In semi-diluted solution collagen (Coll) and CMA present slightly differences in the thixotropic behavior, while CITA has a pronounced thixotropic behavior. Flow and oscillatory measurements revealed an elastic behavior of the collagen solutions, pure and modified with MA or ITA, as the storage modulus (G') has always a superior value compared with the loss modulus (G″). The denaturation temperature (Td) of unmodified collagen increased from 34°C to 40°C for CMA and to 39°C for CITA respectively, by formation of covalent bonds that stabilize the triple helix. PMID:23784667

  1. Stealth surface modification of surface-enhanced Raman scattering substrates for sensitive and accurate detection in protein solutions.

    PubMed

    Sun, Fang; Ella-Menye, Jean-Rene; Galvan, Daniel David; Bai, Tao; Hung, Hsiang-Chieh; Chou, Ying-Nien; Zhang, Peng; Jiang, Shaoyi; Yu, Qiuming

    2015-03-24

    Reliable surface-enhanced Raman scattering (SERS) based biosensing in complex media is impeded by nonspecific protein adsorptions. Because of the near-field effect of SERS, it is challenging to modify SERS-active substrates using conventional nonfouling materials without introducing interference from their SERS signals. Herein, we report a stealth surface modification strategy for sensitive, specific and accurate detection of fructose in protein solutions using SERS by forming a mixed self-assembled monolayer (SAM). The SAM consists of a short zwitterionic thiol, N,N-dimethyl-cysteamine-carboxybetaine (CBT), and a fructose probe 4-mercaptophenylboronic acid (4-MPBA). The specifically designed and synthesized CBT not only resists protein fouling effectively, but also has very weak Raman activity compared to 4-MPBA. Thus, the CBT SAM provides a stealth surface modification to SERS-active substrates. The surface compositions of mixed SAMs were investigated using X-ray photoelectron spectroscopy (XPS) and SERS, and their nonfouling properties were studied with a surface plasmon resonance (SPR) biosensor. The mixed SAM with a surface composition of 94% CBT demonstrated a very low bovine serum albumin (BSA) adsorption (∼3 ng/cm(2)), and moreover, only the 4-MPBA signal appeared in the SERS spectrum. With the use of this surface-modified SERS-active substrate, quantification of fructose over clinically relevant concentrations (0.01-1 mM) was achieved. Partial least-squares regression (PLS) analysis showed that the detection sensitivity and accuracy were maintained for the measurements in 1 mg/mL BSA solutions. This stealth surface modification strategy provides a novel route to introduce nonfouling property to SERS-active substrates for SERS biosensing in complex media.

  2. Enhancing the efficiency of solution-processed polymer:colloidal nanocrystal hybrid photovoltaic cells using ethanedithiol treatment.

    PubMed

    Zhou, Renjia; Stalder, Romain; Xie, Dongping; Cao, Weiran; Zheng, Ying; Yang, Yixing; Plaisant, Marc; Holloway, Paul H; Schanze, Kirk S; Reynolds, John R; Xue, Jiangeng

    2013-06-25

    Advances in colloidal inorganic nanocrystal synthesis and processing have led to the demonstration of organic-inorganic hybrid photovoltaic (PV) cells using low-cost solution processes from blends of conjugated polymer and colloidal nanocrystals. However, the performance of such hybrid PV cells has been limited due to the lack of control at the complex interfaces between the organic and inorganic hybrid active materials. Here we show that the efficiency of hybrid PV devices can be significantly enhanced by engineering the polymer-nanocrystal interface with proper chemical treatment. Using two different conjugated polymers, poly(3-hexylthiophene) (P3HT) and poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT), we show that treating the polymer:nanocrystal hybrid film in an ethanedithiol-containing acetonitrile solution can increase the efficiency of the hybrid PV devices by 30-90%, and a maximum power conversion efficiency of 5.2 ± 0.3% was obtained in the PCPDTBT:CdSe devices at 0.2 sun (AM 1.5G), which was slightly reduced to 4.7 ± 0.3% at 1 sun. The ethanedithiol treatment did not result in significant changes in the morphology and UV-vis optical absorption of the hybrid thin films; however, infrared absorption, NMR, and X-ray photoelectron spectroscopies revealed the effective removal of organic ligands, especially the charged phosphonic acid ligands, from the CdSe nanorod surface after the treatment, accompanied by the possible monolayer passivation of nanorod surfaces with Cd-thiolates. We attribute the hybrid PV cell efficiency increase upon the ethanedithiol treatment to the reduction in charge and exciton recombination sites on the nanocrystal surface and the simultaneous increase in electron transport through the hybrid film.

  3. Structural Changes Associated with Transthyretin Misfolding and Amyloid Formation Revealed by Solution and Solid-State NMR.

    PubMed

    Lim, Kwang Hun; Dasari, Anvesh K R; Hung, Ivan; Gan, Zhehong; Kelly, Jeffery W; Wemmer, David E

    2016-04-01

    Elucidation of structural changes involved in protein misfolding and amyloid formation is crucial for unraveling the molecular basis of amyloid formation. Here we report structural analyses of the amyloidogenic intermediate and amyloid aggregates of transthyretin using solution and solid-state nuclear magnetic resonance (NMR) spectroscopy. Our solution NMR results show that one of the two main β-sheet structures (CBEF β-sheet) is maintained in the aggregation-competent intermediate, while the other DAGH β-sheet is more flexible on millisecond time scales. Magic-angle-spinning solid-state NMR revealed that AB loop regions interacting with strand A in the DAGH β-sheet undergo conformational changes, leading to the destabilized DAGH β-sheet. PMID:26998642

  4. Steady-state thermal-solutal diffusion in a float zone

    NASA Technical Reports Server (NTRS)

    Young, G. W.; Chait, A.

    1989-01-01

    A model for a float zone in a thin vertical sheet is used to study the formation of the zone configuration for both pure and binary systems of Si and GeGa. Equations describing the steady two-dimensional diffusion of solute in the melt and diffusion of heat in the feed material and the product crystal are presented. The material properties, asymptotic solutions for the temperature and concentration profiles, and melting, solidifying, and melt/gas interfacial shapes are determined in the small aspect ratio limit.

  5. Electric-field enhanced performance in catalysis and solid-state devices involving gases

    DOEpatents

    Blackburn, Bryan M.; Wachsman, Eric D.; Van Assche, IV, Frederick Martin

    2015-05-19

    Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

  6. Estimation of salt water upconing using a steady-state solution for partial completion of a pumped well.

    PubMed

    Garabedian, Stephen P

    2013-01-01

    A new steady-state analytical solution to the two-dimensional radial-flow equation was developed for drawdown (head) conditions in an aquifer with constant transmissivity, no-flow conditions at the top and bottom, constant head conditions at a known radial distance, and a partially completed pumping well. The solution was evaluated for accuracy by comparison to numerical simulations using MODFLOW. The solution was then used to estimate the rise of the salt water-fresh water interface (upconing) that occurs under a pumping well, and to calculate the critical pumping rate at which the interface becomes unstable, allowing salt water to enter the pumping well. The analysis of salt water-fresh water interface rise assumed no significant effect on upconing by recharge; this assumption was tested and supported using results from a new steady-state analytical solution developed for recharge under two-dimensional radial-flow conditions. The upconing analysis results were evaluated for accuracy by comparison to those from numerical simulations using SEAWAT for salt water-fresh water interface positions under mild pumping conditions. The results from the equation were also compared with those of a published numerical sharp-interface model applied to a case on Cape Cod, Massachusetts. This comparison indicates that estimating the interface rise and maximum allowable pumping rate using the analytical method will likely be less conservative than the maximum allowable pumping rate and maximum stable interface rise from a numerical sharp-interface model.

  7. Steady-state composition of a two-component gas bubble growing in a liquid solution: self-similar approach.

    PubMed

    Gor, G Yu; Kuchma, A E

    2009-12-21

    The paper presents an analytical description of the growth of a two-component bubble in a binary liquid-gas solution. We obtain asymptotic self-similar time dependence of the bubble radius and analytical expressions for the nonsteady profiles of dissolved gases around the bubble. We show that the necessary condition for the self-similar regime of bubble growth is the constant, steady-state composition of the bubble. The equation for the steady-state composition is obtained. We reveal the dependence of the steady-state composition on the solubility laws of the bubble components. Besides, the universal, independent from the solubility laws, expressions for the steady-state composition are obtained for the case of strong supersaturations, which are typical for the homogeneous nucleation of a bubble.

  8. Engineering solutions for the long-term stabilization and isolation of uranium mill tailings in the United States

    SciTech Connect

    Lommler, J.C.; Cormier, C.; Sanders, D.R.

    1995-12-31

    Engineering solutions for the safe and environmentally protective disposal and isolation of uranium mill tailings in the United States include many factors. Among the factors discussed in this paper are cover design, materials selection, civil engineering, erosive forces, and cost effectiveness. Stabilization and isolation of tailings from humans and the environment are the primary goals of United States uranium mill tailings control standards. The performance of cover designs is addressed with respect to water infiltration, radon exhalation, geotechnical stability, erosion protection, human and animal intrusion prevention, and longevity. The need for and frequency of surveillance efforts to ensure continued disposal system performance are also assessed.

  9. Coefficients for solution of the analytical freezing equation in the range of states for rapid solidification of biological systems.

    PubMed

    Diller, K R

    1990-01-01

    Solution of the classical solidification heat transfer problem for many biological applications involves states for which roots of the transcendental equation associated with the governing differential equation are not available. These roots are calculated and presented for conditions that characterize a large ratio of solid to liquid phase thermal conductivities and diffusivities and large differences between the initial and final temperatures for the cooling process.

  10. New multiplexed all solid state pulser for high power wide aperture kinetically enhanced copper vapor laser.

    PubMed

    Ghodke, D V; Muralikrishnan, K; Singh, Bijendra

    2013-11-01

    A novel multiplexed scheme is demonstrated to combine two or more pulsed solid state pulsers of moderate capabilities. Pulse power supply comprising of two solid state pulsers of ~6 kW rating each in multiplexed mode with common magnetic pulse compression stage was demonstrated and optimized for operating with a wide aperture kinetically enhanced copper vapor laser. Using this new configuration, the multiplexed pulsed power supply was capable of operating efficiently at net repetition-rate of ~13 kHz, 12 kW (wall plug average power), 18-20 kV discharge voltage and pulse rise-time of ~80 ns. The laser under multiplexed configuration delivered un-interrupted output power of about ~80 W with scope of further increase in laser output power in excess of 100 W. PMID:24289383

  11. Enhanced remote earthquake triggering at fluid-injection sites in the midwestern United States.

    PubMed

    van der Elst, Nicholas J; Savage, Heather M; Keranen, Katie M; Abers, Geoffrey A

    2013-07-12

    A recent dramatic increase in seismicity in the midwestern United States may be related to increases in deep wastewater injection. Here, we demonstrate that areas with suspected anthropogenic earthquakes are also more susceptible to earthquake-triggering from natural transient stresses generated by the seismic waves of large remote earthquakes. Enhanced triggering susceptibility suggests the presence of critically loaded faults and potentially high fluid pressures. Sensitivity to remote triggering is most clearly seen in sites with a long delay between the start of injection and the onset of seismicity and in regions that went on to host moderate magnitude earthquakes within 6 to 20 months. Triggering in induced seismic zones could therefore be an indicator that fluid injection has brought the fault system to a critical state. PMID:23846900

  12. Enhanced optical cycling and slowing of YO through rotational state microwave mixing

    NASA Astrophysics Data System (ADS)

    Yan, Bo; Hummon, Matthew; Yeo, Mark; Collopy, Alejandra; Hemmerling, Boerge; Chae, Eunmi; Anderegg, Loic; Ravi, Aakash; Doyle, John; Ye, Jun

    2015-05-01

    In order to address rotational dark states in the molecule yttrium (II) monoxide (YO) and to enhance optical cycling, we demonstrate the remixing of ground electronic state rotational levels using microwave radiation. This mixing technique, in conjunction with a broadband modulated and frequency chirped laser, is used to decelerate a beam of YO from a cryogenic buffer gas cell. The result is a population of molecules with velocities less than 10 m/s, which are sufficiently slow to be loaded into a magneto-optical trap. With two vibrational repump lasers, the cycling transition is closed to the 10-6 level. Additionally, we present progress towards a three dimensional implementation of a magneto-optical trap for YO. This work was supported in part by the Gordon and Betty Moore Foundation through Grant GBMF3852. We also acknowledge support from ARO, AFOSR (MURI), NIST, and NSF.

  13. Enhanced remote earthquake triggering at fluid-injection sites in the midwestern United States.

    PubMed

    van der Elst, Nicholas J; Savage, Heather M; Keranen, Katie M; Abers, Geoffrey A

    2013-07-12

    A recent dramatic increase in seismicity in the midwestern United States may be related to increases in deep wastewater injection. Here, we demonstrate that areas with suspected anthropogenic earthquakes are also more susceptible to earthquake-triggering from natural transient stresses generated by the seismic waves of large remote earthquakes. Enhanced triggering susceptibility suggests the presence of critically loaded faults and potentially high fluid pressures. Sensitivity to remote triggering is most clearly seen in sites with a long delay between the start of injection and the onset of seismicity and in regions that went on to host moderate magnitude earthquakes within 6 to 20 months. Triggering in induced seismic zones could therefore be an indicator that fluid injection has brought the fault system to a critical state.

  14. Broadband enhancement of local density of states using silicon-compatible hyperbolic metamaterials

    SciTech Connect

    Wang, Yu; Inampudi, Sandeep; Capretti, Antonio; Sugimoto, Hiroshi; Fujii, Minoru; Dal Negro, Luca

    2015-06-15

    Light emitting silicon quantum dots by colloidal synthesis were uniformly spin-coated into a 20 nm-thick film and deposited atop a hyperbolic metamaterial of alternating TiN and SiO{sub 2} sub-wavelength layers. Using steady-state and time-resolved photoluminescence spectroscopy as a function of the emission wavelength in partnership with rigorous electromagnetic modeling of dipolar emission, we demonstrate enhanced Local Density of States and coupling to high-k modes in a broad spectral range. These findings provide an alternative approach for the engineering of novel Si-compatible broadband sources that leverage the control of radiative transitions in hyperbolic metamaterials and the flexibility of the widespread Si platform.

  15. Trends in state-level freight accident rates: An enhancement of risk factor development for RADTRAN

    SciTech Connect

    Saricks, C.; Kvitek, T.

    1991-01-01

    Under the Nuclear Waste Policy Act, the Department of Energy's Office of Civilian Radioactive Waste Management (OCRWM) is concerned with understanding and managing risk as it applies to the shipment of spent commercial nuclear reactor fuel. Understanding risk in relation to mode and geography may provide opportunities to minimize radiological and non-radiological risks of transportation. To enhance such an understanding, a set of state-or waterway-specific accident, fatality, and injury rates (expressed as rates per shipment kilometer) by transportation mode and highway administrative class was developed, using publicly-available data bases. Adjustments made to accommodate miscoded or incomplete information in accident data are described, as well as the procedures for estimating state-level flow data. Results indicate that the shipping conditions under which spent fuel is likely to be transported should be less subject to accidents than the average'' shipment within mode. 10 refs., 3 tabs.

  16. Construction of quasi-periodic solutions of state-dependent delay differential equations by the parameterization method II: Analytic case

    NASA Astrophysics Data System (ADS)

    He, Xiaolong; de la Llave, Rafael

    2016-08-01

    We construct analytic quasi-periodic solutions of a state-dependent delay differential equation with quasi-periodically forcing. We show that if we consider a family of problems that depends on one dimensional parameters (with some non-degeneracy conditions), there is a positive measure set Π of parameters for which the system admits analytic quasi-periodic solutions. The main difficulty to be overcome is the appearance of small divisors and this is the reason why we need to exclude parameters. Our main result is proved by a Nash-Moser fast convergent method and is formulated in the a-posteriori format of numerical analysis. That is, given an approximate solution of a functional equation which satisfies some non-degeneracy conditions, we can find a true solution close to it. This is in sharp contrast with the finite regularity theory developed in [18]. We conjecture that the exclusion of parameters is a real phenomenon and not a technical difficulty. More precisely, for generic families of perturbations, the quasi-periodic solutions are only finitely differentiable in open sets in the complement of parameters set Π.

  17. Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

    NASA Astrophysics Data System (ADS)

    Rai, R. N.; Kant, Shiva; Reddi, R. S. B.; Ganesamoorthy, S.; Gupta, P. K.

    2016-01-01

    Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal.

  18. High-resolution three-dimensional structure of a single zinc finger from a human enhancer binding protein in solution.

    PubMed

    Omichinski, J G; Clore, G M; Appella, E; Sakaguchi, K; Gronenborn, A M

    1990-10-01

    The three-dimensional structure of a 30-residue synthetic peptide containing the carboxy-terminal "zinc finger" motif of a human enhancer binding protein has been determined by two-dimensional nuclear magnetic resonance (2D NMR) spectroscopy and hybrid distance geometry-dynamical simulated annealing calculations. The structure determination is based on 487 approximate interproton distance and 63 torsion angle (phi, psi, and chi 1) restraints. A total of 40 simulated annealing structures were calculated, and the atomic rms distribution about the mean coordinate positions (excluding residues 29 and 30 which are ill-defined) is 0.4 A for the backbone atoms, 0.8 A for all atoms, and 0.41 A for all atoms excluding the lysine and arginine side chains, which are disordered. The solution structure of the zinc finger consists of two irregular antiparallel beta-strands connected by an atypical turn (residues 3-12) and a classical alpha-helix (residues 14-24). The zinc is tetrahedrally coordinated to the sulfur atoms of two cysteines (Cys-5 and Cys-8) and to the N epsilon 2 atoms of two histidines (His-21 and His-27). The two cysteine residues are located in the turn connecting the two beta-strands (residues 5-8); one of the histidine ligands (His-21) is in the alpha-helix, while the second histidine (His-27) is at the end of a looplike structure (formed by the end of the alpha-helix and a turn). The general architecture is qualitatively similar to two previously determined low-resolution Cys2-His2 zinc finger structures, although distinct differences can be observed in the beta-strands and turn and in the region around the two histidines coordinated to zinc. Comparison of the overall polypeptide fold of the enhancer binding protein zinc finger with known structures in the crystallographic data base reveals a striking similarity to one region (residues 23-44) of the X-ray structure of proteinase inhibitor domain III of Japanese quail ovomucoid [Papamokos, E., Weber, E., Bode

  19. Nuclear magnetic resonance contrast enhancement study of the gastrointestinal tract of rats and a human volunteer using nontoxic oral iron solutions

    SciTech Connect

    Wesbey, G.E.; Brasch, R.C.; Engelstad, B.L.; Moss, A.A.; Crooks, L.E.; Brito, A.C.

    1983-10-01

    Two dilute oral iron solutions, made from commonly available nonprescription dietary supplements, were found to enhance the gastrointestinal tract in nuclear magnetic resonance imaging of live rats and one human volunteer. The paramagnetic and pharmacologic properties of ferric ammonium citrate were more favorable than those of ferrous sulfate heptahydrate. The paramagnetic iron solutions shorten T1 and T2 relaxation times of water protons in the contrast media-filled gastrointestinal tract, producing easily observable change in NMR intensity. Because these iron solutions are available commercially and are known to be well tolerated, the clinical use of iron-containing NMR contrast agent for the gastrointestinal tract is feasible.

  20. Summary of States' Strategies for ESEA Priority Schools. Solutions. Issue No. 6

    ERIC Educational Resources Information Center

    Perlman, Carole

    2013-01-01

    By the end of 2013, 42 states and the District of Columbia have been granted flexibility regarding specific requirements of the No Child Left Behind Act of 2001 (NCLB) in exchange for rigorous and comprehensive state-developed plans designed to improve educational outcomes for all students, close achievement gaps, increase equity, and improve the…

  1. Summary of States' Strategies and Consequences for ESEA Focus Schools. Solutions. Issue Number 2

    ERIC Educational Resources Information Center

    Perlman, Carole

    2013-01-01

    As of January 1, 2013, 34 states and the District of Columbia have been granted waivers from certain provisions of the Elementary and Secondary Education Act (ESEA). Part of each successful flexibility application was a state accountability system that could identify priority schools (the lowest performing 5% of Title 1 schools) and focus schools…

  2. Efficiency enhancement of solution-processed inverted organic solar cells with a carbon-nanotube-doped active layer

    NASA Astrophysics Data System (ADS)

    Lin, Wen-Kai; Su, Shui-Hsiang; Yeh, Meng-Cheng; Huang, Yang-Chan; Yokoyama, Meiso

    2016-01-01

    Solution-processed titanium-doped ZnO (TZO) is synthesized by the sol-gel method to be the electron-transporting layer (ETL) in an inverted organic solar cell (IOSC). Carbon nanotubes (CNTs) are doped into an active layer of poly(3-hexylthiophene):[6,6]-phenyl C 61 butyric acid methyl ester (P3HT:PCBM). The addition of CNTs in the P3HT:PCBM composite increases the conjugation length of P3HT:PCBM:CNTs, which simultaneously enhances the capacity of the composite to absorb solar energy radiation. Vanadium oxide (V2O5) was spin-coated onto the active layer to be a hole-transporting layer (HTL). The power conversion efficiency (PCE) results indicate that the V2O5 nanobelt structure possesses better phase separation and provides a more efficient surface area for the P3HT:PCBM:CNT active layer to increase photocurrent. The optimized IOSCs exhibited an open circuit voltage (Voc), a short-circuit current density (Jsc), a fill factor (FF), and a PCE of 0.55 V, 6.50 mA/cm2, 58.34%, and 2.20%, respectively, under simulated AM1.5G illumination of 100 mW/cm2.

  3. A two-zone method with an enhanced accuracy for a numerical solution of the diffusion equation

    NASA Astrophysics Data System (ADS)

    Cheon, Jin-Sik; Koo, Yang-Hyun; Lee, Byung-Ho; Oh, Je-Yong; Sohn, Dong-Seong

    2006-12-01

    A variational principle is applied to the diffusion equation to numerically obtain the fission gas release from a spherical grain. The two-zone method, originally proposed by Matthews and Wood, is modified to overcome its insufficient accuracy for a low release. The results of the variational approaches are examined by observing the gas concentration along the grain radius. At the early stage, the concentration near the grain boundary is higher than that at the inner points of the grain in the cases of the two-zone method as well as the finite element analysis with the number of the elements at as many as 10. The accuracy of the two-zone method is considerably enhanced by relocating the nodal points of the two zones. The trial functions are derived as a function of the released fraction. During the calculations, the number of degrees of freedom needs to be reduced to guarantee physically admissible concentration profiles. Numerical verifications are performed extensively. By taking a computational time comparable to the algorithm by Forsberg and Massih, the present method provides a solution with reasonable accuracy in the whole range of the released fraction.

  4. Electrochemically enhanced removal of polycyclic aromatic basic dyes from dilute aqueous solutions by activated carbon cloth electrodes.

    PubMed

    Bayram, Edip; Ayranci, Erol

    2010-08-15

    Open-circuit (OC) adsorption and electrosorption behaviors of three polycyclic aromatic dyes from dilute aqueous solutions onto activated carbon cloth (ACC) were investigated. The selected dyes were crystal violet (BB-3), basic blue7 (BB-7), and basic blue11 (BB-11). OC adsorption and electrosorption processes were monitored by in situ UV-visible spectrophotometry. Electrosorption was carried out by polarization of an ACC electrode, galvanostatically. Considerable enhancements in removal capacity and duration of the dyes were achieved upon polarization of ACC. Kinetic data for OC adsorption and electrosorption were successfully treated according to pseudo-first-order law, and rate constants were determined. Adsorption isotherms were derived, and the data were treated according to Langmuir and Freundlich equations. Both the rate and extent of adsorption and electrosorption of dyes were found to increase in the order of BB-7 < BB-11 < BB-3. This order was discussed in terms of correlation between sizes of dye species and of ACC pores. Electrodesorption experiments were carried out to explore possibilities of regeneration of ACC. PMID:20704233

  5. Thiocyanate-Capped Nanocrystal Colloids: Vibrational Reporter of Surface Chemistry and Solution-Based Route to Enhanced Coupling in Nanocrystal Solids

    SciTech Connect

    Fafarman, AT; Koh, WK; Diroll, BT; Kim, DK; Ko, DK; Oh, SJ; Ye, XC; Doan-Nguyen, V; Crump, MR; Reifsnyder, DC; Murray, CB; Kagan, CR

    2011-10-05

    Ammonium thiocyanate (NH(4)SCN) is introduced to exchange the long, insulating ligands used in colloidal nanocrystal (NC) synthesis. The short, air-stable, environmentally benign thiocyanate ligand electrostatically stabilizes a variety of semiconductor and metallic NCs in polar solvents, allowing solution-based deposition of NCs into thin-film NC solids. NH(4)SCN is also effective in replacing ligands on NCs after their assembly into the solid state. The spectroscopic properties of this ligand provide unprecedented insight into the chemical and electronic nature of the surface of the NCs. Spectra indicate that the thiocyanate binds to metal sites on the NC surface and is sensitive to atom type and NC surface charge. The short, thiocyanate ligand gives rise to significantly enhanced electronic coupling between NCs as evidenced by large bathochromic shifts in the absorption spectra of CdSe and CdTe NC thin films and by conductivities as high as (2 +/- 0.7) x 10(3) Omega(-1) cm(-1) for Au NC thin films deposited from solution. NH(4)SCN treatment of PbTe NC films increases the conductivity by 10(13), allowing the first Hall measurements of nonsintered NC solids, with Hall effect mobilities of 2.8 +/- 0.7 cm(2)/(V.s). Thiocyanate-capped CdSe NC thin films form photodetectors exhibiting sensitive photoconductivity of 10(-5) Omega(-1) cm(-1) under 30 mW/cm(2) of 488 nm illumination with I(photo)/I(dark) > 10(3) and form n-channel thin-film transistors with electron mobilities of 1.5 +/- 0.7 cm(2)/(V.s), a current modulation of >10(6), and a subthreshold swing of 0.73 V/decade.

  6. Thiocyanate-capped nanocrystal colloids: vibrational reporter of surface chemistry and solution-based route to enhanced coupling in nanocrystal solids.

    PubMed

    Fafarman, Aaron T; Koh, Weon-kyu; Diroll, Benjamin T; Kim, David K; Ko, Dong-Kyun; Oh, Soong Ju; Ye, Xingchen; Doan-Nguyen, Vicky; Crump, Michael R; Reifsnyder, Danielle C; Murray, Christopher B; Kagan, Cherie R

    2011-10-01

    Ammonium thiocyanate (NH(4)SCN) is introduced to exchange the long, insulating ligands used in colloidal nanocrystal (NC) synthesis. The short, air-stable, environmentally benign thiocyanate ligand electrostatically stabilizes a variety of semiconductor and metallic NCs in polar solvents, allowing solution-based deposition of NCs into thin-film NC solids. NH(4)SCN is also effective in replacing ligands on NCs after their assembly into the solid state. The spectroscopic properties of this ligand provide unprecedented insight into the chemical and electronic nature of the surface of the NCs. Spectra indicate that the thiocyanate binds to metal sites on the NC surface and is sensitive to atom type and NC surface charge. The short, thiocyanate ligand gives rise to significantly enhanced electronic coupling between NCs as evidenced by large bathochromic shifts in the absorption spectra of CdSe and CdTe NC thin films and by conductivities as high as (2 ± 0.7) × 10(3) Ω(-1) cm(-1) for Au NC thin films deposited from solution. NH(4)SCN treatment of PbTe NC films increases the conductivity by 10(13), allowing the first Hall measurements of nonsintered NC solids, with Hall effect mobilities of 2.8 ± 0.7 cm(2)/(V·s). Thiocyanate-capped CdSe NC thin films form photodetectors exhibiting sensitive photoconductivity of 10(-5) Ω(-1) cm(-1) under 30 mW/cm(2) of 488 nm illumination with I(photo)/I(dark) > 10(3) and form n-channel thin-film transistors with electron mobilities of 1.5 ± 0.7 cm(2)/(V·s), a current modulation of >10(6), and a subthreshold swing of 0.73 V/decade.

  7. Twenty State Policies to Enhance States' Prosperity and Create Bright Futures for America's Children, Families and Communities. Policy Matters: 2008 Data Update

    ERIC Educational Resources Information Center

    Center for the Study of Social Policy, 2008

    2008-01-01

    As of March 2008, over half of U.S. states are facing projected budget shortfalls for the coming fiscal year. During economic downturns such as this, opportunities available to hard-working, low-wage families are diminished. These conditions create growing concerns for policymakers who must, with fewer state resources, enhance opportunities and…

  8. Reduced linewidth enhancement factor due to excited state transition of quantum dot lasers.

    PubMed

    Xu, Peng-Fei; Ji, Hai-Ming; Xiao, Jin-Long; Gu, Yong-Xian; Huang, Yong-Zhen; Yang, Tao

    2012-04-15

    The carrier induced refractive index change and linewidth enhancement factor α due to ground-state (GS) and excited-state (ES) transitions have been compared by measuring the optical gain spectra from an InAs/GaAs quantum dot (QD) laser structure. It is shown that the ES transition exhibits a reduced α-factor compared to the value due to the GS transition. This result can be explained by the α-factor due to the ES transition having a smaller increase from the non-resonant carriers in the combined state of the wetting layer and InGaAs strain reducing layer than the α-factor increase due to the GS transition, since the relaxation time for carriers from the combined state of the wetting layer and InGaAs strain reducing layer to the ES is shorter than to the GS. The result reported here shows another advantage of using ES QD lasers for optical communication, in addition to their higher modulation speed.

  9. Surface-state enhancement of tunneling thermopower on the Ag(111) surface.

    PubMed

    Maksymovych, Petro; Kelly, Simon J; Cerdá, Jorge I

    2014-12-23

    Thermoelectric effects in tunnel junctions are currently being revisited for their prospects in cooling and energy harvesting applications, and as sensitive probes of electron transport. Quantitative interpretation of these effects calls for advances in both theory and experiment, particularly with respect to the electron transmission probability across a tunnel barrier which encodes the energy dependence and the magnitude of tunneling thermopower. Using noble metal surfaces as clean model systems, we demonstrate a comparatively simple and quantitative approach where the transmission probability is directly measured experimentally. Importantly, we estimate not only thermovoltage, but also its energy and temperature dependencies. We have thus resolved surface-state enhancement of thermovoltage, which manifests as 10-fold enhancement of thermopower on terraces of the Ag(111) surface compared to single-atom step sites and surface-supported nanoparticles. To corroborate experimental analysis, the methodology was applied to the transmission probability obtained from first-principles calculations for the (111) surfaces of the three noble metals, finding good agreement between overall trends. Surface-state effects themselves point to a possibility of achieving competitive performance of all-metal tunnel junctions when compared to molecular junctions. At the same time, the approach presented here opens up possibilities to investigate the properties of nominally doped or gated thermoelectric tunnel junctions as well as temperature gradient in nanometer gaps.

  10. Enhanced magnetic flux density mapping using coherent steady state equilibrium signal in MREIT

    NASA Astrophysics Data System (ADS)

    Jeong, Woo Chul; Lee, Mun Bae; Sajib, Saurav Z. K.; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2016-03-01

    Measuring the z-component of magnetic flux density B = (Bx, By, Bz) induced by transversally injected current, magnetic resonance electrical impedance tomography (MREIT) aims to visualize electrical property (current density and/or conductivity distribution) in a three-dimensional imaging object. For practical implementations of MREIT technique, it is critical to reduce injection of current pulse within safety requirements. With the goal of minimizing the noise level in measured Bz data, we propose a new method to enhance the measure Bz data using steady-state coherent gradient multi-echo (SSC-GME) MR pulse sequence combining with injection current nonlinear encoding (ICNE) method in MREIT, where the ICNE technique injects current during a readout gradient to maximize the signal intensity of phase signal including Bz. The total phase offset in SSC-GME includes additional magnetic flux density due to the injected current, which is different from the phase signal for the conventional spoiled MR pulse sequence. We decompose the magnetization precession phase from the total phase offset including Bz and optimize Bz data using the steady-state equilibrium signal. Results from a real phantom experiment including different kinds of anomalies demonstrated that the proposed method enhanced Bz comparing to a conventional spoiled pulse sequence.

  11. Efficient solution of liquid state integral equations using the Newton-GMRES algorithm

    NASA Astrophysics Data System (ADS)

    Booth, Michael J.; Schlijper, A. G.; Scales, L. E.; Haymet, A. D. J.

    1999-06-01

    We present examples of the accurate, robust and efficient solution of Ornstein-Zernike type integral equations which describe the structure of both homogeneous and inhomogeneous fluids. In this work we use the Newton-GMRES algorithm as implemented in the public-domain nonlinear Krylov solvers NKSOL [ P. Brown, Y. Saad, SIAM J. Sci. Stat. Comput. 11 (1990) 450] and NITSOL [ M. Pernice, H.F. Walker, SIAM J. Sci. Comput. 19 (1998) 302]. We compare and contrast this method with more traditional approaches in the literature, using Picard iteration (successive-substitution) and hybrid Newton-Raphson and Picard methods, and a recent vector extrapolation method [ H.H.H. Homeier, S. Rast, H. Krienke, Comput. Phys. Commun. 92 (1995) 188]. We find that both the performance and ease of implementation of these nonlinear solvers recommend them for the solution of this class of problem.

  12. The Common Core State Standards: An Opportunity to Enhance Formative Assessment in History/Social Studies Classrooms

    ERIC Educational Resources Information Center

    Ateh, Comfort M.; Wyngowski, Aaron J.

    2015-01-01

    This article discusses the opportunity that the Common Core State Standards (CCSS) present for enhancing formative assessment (FA) in history and social studies classrooms. There is evidence that FA can enhance learning for students if implemented well. Unfortunately, teachers continue to be challenged in implementing FA in their classrooms. We…

  13. An alternative scheme to find glass state solutions using integral equation theory for the pair structure

    NASA Astrophysics Data System (ADS)

    Bomont, Jean-Marc; Pastore, Giorgio

    2015-09-01

    We propose and discuss a straightforward search protocol for the glass-like solutions of the integral equations of the two-replica approach to the random first-order transition theory of the liquid-glass transition. The new numerical strategy supplements those recently introduced by Jean-Pierre Hansen and ourselves. A few results for inverse power (1/r12) fluid are discussed and critically compared with results from other approaches.

  14. Concentration selective hydration and phase states of hydroxyethyl cellulose (HEC) in aqueous solutions.

    PubMed

    Arfin, Najmul; Bohidar, H B

    2012-04-01

    Solution behaviour of hydroxyethyl cellulose (HEC) is reported in the polymer concentration range spanning over two decades (c=0.002-5% (w/v)). The results conclude the following: (i) dilute solution regime prevailed for c<0.2% (w/v), flexible HEC fibres of typical length ≈ 1 μm and persistence length ≈ 10 nm were found here, (ii) for 0.2solution behaved with melt-like attributes with substantial embedded heterogeneity; viscous to elastic transition was observed in this region. Raman spectral, and DSC data indicated distinctive hydration of HEC fibres in the aforesaid concentration regimes. Cole-Cole plots revealed phase homogeneity and miscibility was limited to concentrations less than ~2% (w/v). For higher polymer concentrations, strong fibre-fibre interactions prevailed and samples became heterogeneous.

  15. General three-state model with biased population replacement: analytical solution and application to language dynamics.

    PubMed

    Colaiori, Francesca; Castellano, Claudio; Cuskley, Christine F; Loreto, Vittorio; Pugliese, Martina; Tria, Francesca

    2015-01-01

    Empirical evidence shows that the rate of irregular usage of English verbs exhibits discontinuity as a function of their frequency: the most frequent verbs tend to be totally irregular. We aim to qualitatively understand the origin of this feature by studying simple agent-based models of language dynamics, where each agent adopts an inflectional state for a verb and may change it upon interaction with other agents. At the same time, agents are replaced at some rate by new agents adopting the regular form. In models with only two inflectional states (regular and irregular), we observe that either all verbs regularize irrespective of their frequency, or a continuous transition occurs between a low-frequency state, where the lemma becomes fully regular, and a high-frequency one, where both forms coexist. Introducing a third (mixed) state, wherein agents may use either form, we find that a third, qualitatively different behavior may emerge, namely, a discontinuous transition in frequency. We introduce and solve analytically a very general class of three-state models that allows us to fully understand these behaviors in a unified framework. Realistic sets of interaction rules, including the well-known naming game (NG) model, result in a discontinuous transition, in agreement with recent empirical findings. We also point out that the distinction between speaker and hearer in the interaction has no effect on the collective behavior. The results for the general three-state model, although discussed in terms of language dynamics, are widely applicable.

  16. General three-state model with biased population replacement: Analytical solution and application to language dynamics

    NASA Astrophysics Data System (ADS)

    Colaiori, Francesca; Castellano, Claudio; Cuskley, Christine F.; Loreto, Vittorio; Pugliese, Martina; Tria, Francesca

    2015-01-01

    Empirical evidence shows that the rate of irregular usage of English verbs exhibits discontinuity as a function of their frequency: the most frequent verbs tend to be totally irregular. We aim to qualitatively understand the origin of this feature by studying simple agent-based models of language dynamics, where each agent adopts an inflectional state for a verb and may change it upon interaction with other agents. At the same time, agents are replaced at some rate by new agents adopting the regular form. In models with only two inflectional states (regular and irregular), we observe that either all verbs regularize irrespective of their frequency, or a continuous transition occurs between a low-frequency state, where the lemma becomes fully regular, and a high-frequency one, where both forms coexist. Introducing a third (mixed) state, wherein agents may use either form, we find that a third, qualitatively different behavior may emerge, namely, a discontinuous transition in frequency. We introduce and solve analytically a very general class of three-state models that allows us to fully understand these behaviors in a unified framework. Realistic sets of interaction rules, including the well-known naming game (NG) model, result in a discontinuous transition, in agreement with recent empirical findings. We also point out that the distinction between speaker and hearer in the interaction has no effect on the collective behavior. The results for the general three-state model, although discussed in terms of language dynamics, are widely applicable.

  17. Structural study of low concentration LiCl aqueous solutions in the liquid, supercooled, and hyperquenched glassy states.

    PubMed

    Winkel, K; Seidl, M; Loerting, T; Bove, L E; Imberti, S; Molinero, V; Bruni, F; Mancinelli, R; Ricci, M A

    2011-01-14

    Neutron diffraction experiments on a solution of LiCl in water (R = 40) at ambient conditions and in the supercooled and hyperquenched states are reported and analyzed within the empirical potential structure refinement framework. Evidence for the modifications of the microscopic structure of the solvent in the presence of such a small amount of salt is found at all investigated thermodynamic states. On the other hand, it is evident that the structure of the hyperquenched salty sample is similar to that of pure low density amorphous water, although all the peaks of the radial distribution functions are broader in the present case. Changes upon supercooling or hyperquenching of the ion's hydration shells and contacts are of limited size and evidence for segregation phenomena at these states does not clearly show up, although the presence of water separated contacts between ion of the same sign is intriguing. PMID:21241128

  18. Grassland to shrubland state transitions enhance carbon sequestration in the northern Chihuahuan Desert.

    PubMed

    Petrie, M D; Collins, S L; Swann, A M; Ford, P L; Litvak, M E

    2015-03-01

    The replacement of native C4 -dominated grassland by C3 -dominated shrubland is considered an ecological state transition where different ecological communities can exist under similar environmental conditions. These state transitions are occurring globally, and may be exacerbated by climate change. One consequence of the global increase in woody vegetation may be enhanced ecosystem carbon sequestration, although the responses of arid and semiarid ecosystems may be highly variable. During a drier than average period from 2007 to 2011 in the northern Chihuahuan Desert, we found established shrubland to sequester 49 g C m(-2) yr(-1) on average, while nearby native C4 grassland was a net source of 31 g C m(-2) yr(-1) over this same period. Differences in C exchange between these ecosystems were pronounced--grassland had similar productivity compared to shrubland but experienced higher C efflux via ecosystem respiration, while shrubland was a consistent C sink because of a longer growing season and lower ecosystem respiration. At daily timescales, rates of carbon exchange were more sensitive to soil moisture variation in grassland than shrubland, such that grassland had a net uptake of C when wet but lost C when dry. Thus, even under unfavorable, drier than average climate conditions, the state transition from grassland to shrubland resulted in a substantial increase in terrestrial C sequestration. These results illustrate the inherent tradeoffs in quantifying ecosystem services that result from ecological state transitions, such as shrub encroachment. In this case, the deleterious changes to ecosystem services often linked to grassland to shrubland state transitions may at least be partially offset by increased ecosystem carbon sequestration.

  19. Chain dimensions in free and immobilized brush states of polysulfobetaine in aqueous solution at various salt concentrations

    NASA Astrophysics Data System (ADS)

    Terayama, Y.; Arita, H.; Ishikawa, T.; Kikuchi, M.; Mitamura, K.; Kobayashi, M.; Yamada, N. L.; Takahara, A.

    2011-01-01

    The chain dimensions of free and immobilized polysulfobetaine in aqueous solution at various salt concentrations were investigated by size-exclusion chromatography with multiangle light scattering and neutron reflectivity measurement, respectively. The dependence of the z-average mean square radius of gyration (z1/2) on the weight-average molecular weight (Mw) of free poly(3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfo-nate) (MAPS) in aqueous solution at salt concentrations of 74, 100, 200, and 500 mM was described by the perturbed wormlike chain model using the chain stiffness parameter λ-1 the molar mass per unit contour length ML, and the excluded volume effect B. B increased from 0 to 1.8 nm with increasing salt concentration to 500 mM due to the screening of attractive electrostatic interaction between ammonium cations and sulfonyl anions by salt ions. The swollen structure of the poly(MAPS) brush in D2O changed from a shrunken state to a relatively extended state with increasing salt concentration from 0 to 500 mM NaCl/D2O solution. The thickness of the swollen poly(MAPS) brush in 500 mM NaCl/D2O was 9.0 times greater than 2z1/2 of free poly(MAPS) due to high osmotic pressure generated by the excluded volume effect of densely grafted polymer chains.

  20. ATP ground- and transition-states of bacterial enhancer binding AAA+ ATPases support complex formation with their target protein, σ54.

    PubMed Central

    Chen, Baoyu; Doucleff, Michaeleen; Wemmer, David E.; De Carlo, Sacha; Huang, Hector H.; Nogales, Eva; Hoover, Timothy R.; Kondrashkina, Elena; Guo, Liang; Nixon, B. Tracy

    2009-01-01

    Summary Transcription initiation by the σ54-form of bacterial RNA polymerase requires hydrolysis of ATP by an enhancer binding protein (EBP). We present SAS-based solution structures of the ATPase domain of the EBP NtrC1 from Aquifex aeolicus in different nucleotide states. Structures of apo protein and that bound to AMPPNP or ADP-BeFx (ground-state mimics), ADP-AlFx (a transition-state mimic) or ADP (product) show substantial changes in the position of the GAFTGA loops that contact polymerase, particularly upon conversion from the apo state to the ADP-BeFx state, and from the ADP-AlFx state to the ADP state. Binding of the ATP analogs stabilizes the oligomeric form of the ATPase and its binding to σ54, with ADP-AlFx having the largest effect. These data indicate that ATP binding promotes a conformational change that stabilizes complexes between EBPs and σ54, while subsequent hydrolysis and phosphate release drive the conformational change needed to open the polymerase / promoter complex. PMID:17437715

  1. Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity.

    PubMed

    Huang, Zhujian; Wu, Pingxiao; Gong, Beini; Dai, Yaping; Chiang, Pen-Chi; Lai, Xiaolin; Yu, Guangwei

    2016-01-01

    To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH2) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt, APTES4.0CEC-Mt) with enhanced adsorption capacity for Co2+. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co2+ by APTES-Mt was evaluated. The results indicated that adsorption of Co2+ onto Ca-Mt, APTES1.0CEC-Mt and APTES2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co2+ onto APTES3.0CEC-Mt and APTES4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt and APTES4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co2+ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co2+-rich wastewater. PMID:27448094

  2. Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity.

    PubMed

    Huang, Zhujian; Wu, Pingxiao; Gong, Beini; Dai, Yaping; Chiang, Pen-Chi; Lai, Xiaolin; Yu, Guangwei

    2016-01-01

    To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH2) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt, APTES4.0CEC-Mt) with enhanced adsorption capacity for Co2+. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co2+ by APTES-Mt was evaluated. The results indicated that adsorption of Co2+ onto Ca-Mt, APTES1.0CEC-Mt and APTES2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co2+ onto APTES3.0CEC-Mt and APTES4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt and APTES4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co2+ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co2+-rich wastewater.

  3. Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity

    PubMed Central

    Huang, Zhujian; Gong, Beini; Dai, Yaping; Chiang, Pen-Chi; Lai, Xiaolin; Yu, Guangwei

    2016-01-01

    To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH2) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt, APTES4.0CEC-Mt) with enhanced adsorption capacity for Co2+. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co2+ by APTES-Mt was evaluated. The results indicated that adsorption of Co2+ onto Ca-Mt, APTES1.0CEC-Mt and APTES2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co2+ onto APTES3.0CEC-Mt and APTES4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt and APTES4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co2+ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co2+-rich wastewater. PMID:27448094

  4. Tuberculosis genotyping information management system: enhancing tuberculosis surveillance in the United States.

    PubMed

    Ghosh, Smita; Moonan, Patrick K; Cowan, Lauren; Grant, Juliana; Kammerer, Steve; Navin, Thomas R

    2012-06-01

    Molecular characterization of Mycobacterium tuberculosis complex isolates (genotyping) can be used by public health programs to more readily identify tuberculosis (TB) transmission. The Centers for Disease Control and Prevention's National Tuberculosis Genotyping Service has offered M. tuberculosis genotyping for every culture-confirmed case in the United States since 2004. The TB Genotyping Information Management System (TB GIMS), launched in March 2010, is a secure online database containing genotype results linked with case characteristics from the national TB registry for state and local TB programs to access, manage and analyze these data. As of September 2011, TB GIMS contains genotype results for 89% of all culture-positive TB cases for 2010. Over 400 users can generate local and national reports and maps using TB GIMS. Automated alerts on geospatially concentrated cases with matching genotypes that may represent outbreaks are also generated by TB GIMS. TB genotyping results are available to enhance national TB surveillance and apply genotyping results to conduct TB control activities in the United States. PMID:22044522

  5. Tuberculosis genotyping information management system: enhancing tuberculosis surveillance in the United States.

    PubMed

    Ghosh, Smita; Moonan, Patrick K; Cowan, Lauren; Grant, Juliana; Kammerer, Steve; Navin, Thomas R

    2012-06-01

    Molecular characterization of Mycobacterium tuberculosis complex isolates (genotyping) can be used by public health programs to more readily identify tuberculosis (TB) transmission. The Centers for Disease Control and Prevention's National Tuberculosis Genotyping Service has offered M. tuberculosis genotyping for every culture-confirmed case in the United States since 2004. The TB Genotyping Information Management System (TB GIMS), launched in March 2010, is a secure online database containing genotype results linked with case characteristics from the national TB registry for state and local TB programs to access, manage and analyze these data. As of September 2011, TB GIMS contains genotype results for 89% of all culture-positive TB cases for 2010. Over 400 users can generate local and national reports and maps using TB GIMS. Automated alerts on geospatially concentrated cases with matching genotypes that may represent outbreaks are also generated by TB GIMS. TB genotyping results are available to enhance national TB surveillance and apply genotyping results to conduct TB control activities in the United States.

  6. Plasticity between Epithelial and Mesenchymal States Unlinks EMT from Metastasis-Enhancing Stem Cell Capacity

    PubMed Central

    Beerling, Evelyne; Seinstra, Daniëlle; de Wit, Elzo; Kester, Lennart; van der Velden, Daphne; Maynard, Carrie; Schäfer, Ronny; van Diest, Paul; Voest, Emile; van Oudenaarden, Alexander; Vrisekoop, Nienke; van Rheenen, Jacco

    2016-01-01

    Summary Forced overexpression and/or downregulation of proteins regulating epithelial-to-mesenchymal transition (EMT) has been reported to alter metastasis by changing migration and stem cell capacity of tumor cells. However, these manipulations artificially keep cells in fixed states, while in vivo cells may adapt transient and reversible states. Here, we have tested the existence and role of epithelial-mesenchymal plasticity in metastasis of mammary tumors without artificially modifying EMT regulators. In these tumors, we found by intravital microscopy that the motile tumor cells have undergone EMT, while their epithelial counterparts were not migratory. Moreover, we found that epithelial-mesenchymal plasticity renders any EMT-induced stemness differences, as reported previously, irrelevant for metastatic outgrowth, because mesenchymal cells that arrive at secondary sites convert to the epithelial state within one or two divisions, thereby obtaining the same stem cell potential as their arrived epithelial counterparts. We conclude that epithelial-mesenchymal plasticity supports migration but additionally eliminates stemness-enhanced metastatic outgrowth differences. PMID:26947068

  7. Asymptotic Steady-state Solution to a Bow Shock with an Infinite Mach Number

    NASA Astrophysics Data System (ADS)

    Yalinewich, Almog; Sari, Re'em

    2016-08-01

    The problem of a cold gas flowing past a stationary obstacle is considered. We study the bow shock that forms around the obstacle and show that at large distances from the obstacle the shock front forms a parabolic solid of revolution. The profiles of the hydrodynamic variables in the interior of the shock are obtained by solution of the hydrodynamic equations in parabolic coordinates. The results are verified with a hydrodynamic simulation. The drag force on the obstacle is also calculated. Finally, we use these results to model the bow shock around an isolated neutron star.

  8. Contact-enhanced transparent silver nanowire network for all solution-based top-contact metal-oxide thin-film transistors.

    PubMed

    Kim, Yong-Hoon; Kim, Tae-Hyoung; Lee, Yeji; Kim, Jong-Woong; Kim, Jaekyun; Park, Sung Kyu

    2014-11-01

    In this paper, we investigate contact-enhanced transparent silver nanowire (Ag NW) network for solution-processed metal-oxide thin-film transistors (TFTs). Mechanical roll pressing was applied to a bar-coated Ag NW film to enhance the inter-nanowire connectivity. As a result, the sheet resistance of the Ag NW film was decreased from 119.5 ψ/square to 92.4 ψ/square, and more stable and enhanced TFT characteristics were achieved when the roll-pressed Ag NW was employed as source/drain electrodes. In addition, a non-acidic wet etching method was developed to pattern the Ag NW electrodes to construct top-contact geometry indium-gallium-zinc oxide TFTs. From the results, it is believed that the mechanical roll pressing and non-acidic wet etching method may be utilized in realizing all solution-based transparent metal-oxide TFTs. PMID:25958491

  9. Elderly care: similarities and solutions in Denmark and the United States.

    PubMed

    Raffel, N K; Raffel, M W

    1987-01-01

    Denmark, like the United States and other developed countries, is experiencing an increase in the percentage of dependent elderly in its population. They consume a disproportionate share of health and social services at a time when government is attempting to contain costs. Both countries face similar problems in caring for the elderly--problems of escalating hospital costs, dramatically increased nursing home costs, and insufficient public revenues to cover their entire care. Denmark has developed a wide range of services for the elderly--home help, home nursing, adult day care centers, day nursing homes, and sheltered housing. The response in the United States has taken somewhat different directions, although in both countries home and community services have been expanded as a substitute for expensive institutional care. The possible relevance of the U.S. experience in these areas to Denmark and lessons that the United States might learn from the Scandinavian country are discussed.

  10. αB-Crystallin: A Hybrid Solid-Solution State NMR Investigation Reveals Structural Aspects of the Heterogeneous Oligomer

    PubMed Central

    Jehle, Stefan; van Rossum, Barth; Stout, Joseph R.; Noguchi, Satoshi R.; Falber, Katja; Rehbein, Kristina; Oschkinat, Hartmut; Klevit, Rachel E.; Rajagopal, Ponni

    2009-01-01

    Summary Atomic level structural information on αB-Crystallin (αB), a prominent member of the small Heat Shock Protein (sHSP) family has been a challenge to obtain due its polydisperse, oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on ∼ 580 kDa human αB assembled from 175-residue, 20 kDa subunits. An ∼100-residue α-crystallin domain is common to all sHSPs and solution-state NMR was performed on two different α-crystallin domain constructs isolated from αB. In vitro, the chaperone-like activities of full-length αB and the isolated α-crystallin domain are identical. Chemical shifts of the backbone and the Cβ resonances have been obtained for residues 64-162 (α-crystallin domain plus part of the C-terminus) in αB and the isolated α-crystallin domain by solid- and solution-state NMR, respectively. Both sets of data strongly predict six β-strands in the α-crystallin domain. A majority of residues in the α-crystallin domain have similar chemical shifts in both solid- and solution-state indicating a similar structure for the domain in its isolated and oligomeric forms. Sites of inter-subunit interaction are identified from chemical shift differences that cluster to specific regions of the α-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within αB. Evidence for a novel dimerization motif in the human α-crystallin domain is obtained by a comparison of (i) solid- and solution-state chemical shift data and (ii) 1H-15N HSQC spectra as a function of pH. The isolated α-crystallin domain undergoes a dimer-monomer transition over the pH range of 7.5 to 6.8. This steep pH-dependent switch may be important for αB to function optimally, e.g., to preserve the filament integrity of cardiac muscle proteins such as actin and desmin during cardiac ischemia which

  11. Supersymmetric factorization yields exact solutions to the molecular Stark-effect problem for stretched states

    SciTech Connect

    Lemeshko, Mikhail; Mustafa, Mustafa; Kais, Sabre; Friedrich, Bretislav

    2011-04-15

    By invoking supersymmetry, we found a condition under which the Stark-effect problem for a polar and polarizable molecule subject to nonresonant electric fields becomes exactly solvable for the |J-tilde=m,m> family of stretched states. The analytic expressions for the wave function and eigenenergy and other expectation values allow one to readily reverse-engineer the problem of finding the values of the interaction parameters required for creating quantum states with preordained characteristics. The method also allows the construction of families of isospectral potentials, realizable with combined fields.

  12. Recursive solution of number of reachable states of a simple subclass of FMS

    NASA Astrophysics Data System (ADS)

    Chao, Daniel Yuh

    2014-03-01

    This paper aims to compute the number of reachable (forbidden, live and deadlock) states for flexible manufacturing systems (FMS) without the construction of reachability graph. The problem is nontrivial and takes, in general, an exponential amount of time to solve. Hence, this paper focusses on a simple version of Systems of Simple Sequential Processes with Resources (S3PR), called kth-order system, where each resource place holds one token to be shared between two processes. The exact number of reachable (forbidden, live and deadlock) states can be computed recursively.

  13. Numerical solution of steady-state buoyancy-driven flow of an incompressible fluid with temperature dependent viscosity

    SciTech Connect

    Abrous, A.; Emery, A.F.

    1995-12-31

    The steady-state, buoyancy-driven flow of an incompressible fluid with temperature dependent viscosity within a square enclosure is solved numerically and the results are presented. The benchmark problem`s geometrical and mathematical descriptions adopted herein are those specified by the AdHoc Committee of Computational Heat Transfer which is compiling different solutions for this benchmark problem in heat transfer analysis. The objective is to compare solutions computed with several different algorithmic approaches for a problem having a large variation in fluid viscosity, characteristic of modeling turbulent flows with eddy diffusivity concepts. The results of the present analysis are submitted as a contribution to this comparison exercise that has for objective the assessment of the numerical accuracy of modeling the diffusion terms in the conservation equations with variable property.

  14. Transplantation of storm-generated coral fragments to enhance Caribbean coral reefs: A successful method but not a solution

    USGS Publications Warehouse

    Garrison, V.H.; Ward, G.

    2012-01-01

    In response to dramatic losses of reef-building corals and ongoing lack of recovery, a small-scale coral transplant project was initiated in the Caribbean (U.S. Virgin Islands) in 1999 and was followed for 12 years. The primary objectives were to (1) identify a source of coral colonies for transplantation that would not result in damage to reefs, (2) test the feasibility of transplanting storm-generated coral fragments, and (3) develop a simple, inexpensive method for transplanting fragments that could be conducted by the local community. The ultimate goal was to enhance abundance of threatened reef-building species on local reefs. Storm-produced coral fragments of two threatened reef-building species [Acropora palmata and A. cervicornis (Acroporidae)] and another fast-growing species [Porites porites (Poritidae)] were collected from environments hostile to coral fragment survival and transplanted to degraded reefs. Inert nylon cable ties were used to attach transplanted coral fragments to dead coral substrate. Survival of 75 reference colonies and 60 transplants was assessed over 12 years. Only 9% of colonies were alive after 12 years: no A. cervicornis; 3% of A. palmata transplants and 18% of reference colonies; and 13% of P. porites transplants and 7% of reference colonies. Mortality rates for all species were high and were similar for transplant and reference colonies. Physical dislodgement resulted in the loss of 56% of colonies, whereas 35% died in place. Only A. palmata showed a difference between transplant and reference colony survival and that was in the first year only. Location was a factor in survival only for A. palmata reference colonies and after year 10. Even though the tested methods and concepts were proven effective in the field over the 12-year study, they do not present a solution. No coral conservation strategy will be effective until underlying intrinsic and/or extrinsic factors driving high mortality rates are understood and mitigated or

  15. Evaluation and comparison of 1,2-indanedione and 1,8-diazafluoren-9-one solutions for the enhancement of latent fingerprints on porous surfaces.

    PubMed

    D'Elia, Valentina; Materazzi, Stefano; Iuliano, Gianpaolo; Niola, Luca

    2015-09-01

    1,2-indanedione (1,2-IND) and 1,8-diazafluoren-9-one (DFO) are used in the forensic field to enhance latent fingerprints deposited on porous surfaces due to the formation of fluorescent products by reacting with the amino acids present in the papillary exudate. The study was carried out in collaboration with the Fingerprints and Photography Section of the Carabinieri Scientific Investigation Department (RIS) of Rome, in which laboratories, until now, DFO has been the most used because of its excellent enhancing properties, even if it is more expensive and relatively toxic in comparison with the 1,2-IND. The aim of this work was then to evaluate and to compare the effectiveness of three solutions of 1,2-IND in different formulations and a DFO solution employed as single enhancing treatments, in order to assess whether it was possible to replace a reagent with the other obtaining equally satisfying results. In this case, white office paper was selected as deposit surface since it also permitted one to observe those reaction products that appear visible to a naked eye. Beside to a qualitative study of the visual characteristic of the enhanced fingerprints, further quantitative studies were conducted on the intensity of fluorescence of the products and on the consumption of amino acids during the reaction. The analyses, which at first were conducted on standard samples, were then repeated on real samples to validate the results obtained. The DFO confirmed its excellent enhancement properties, but also one of the three solutions of 1,2-IND showed comparable properties in terms of enhanced fingerprint definition and stability over time from the completion of a crime. As a result, we proved that a selected 1,2-IND formulation may replace with satisfactory achievements the DFO solution currently employed, providing also advantages from the point of view of safety and cost savings.

  16. Structural-energy states of water and aqueous solutions under external influences

    NASA Astrophysics Data System (ADS)

    Gorlenko, Nikolay; Laptev, Boris; Sidorenko, Galina; Sarkisov, Yuri; Minakova, Tamara; Kylchenko, Anton; Zubkova, Olga

    2016-01-01

    Methods are proposed for evaluating changes in the structure of water or aqueous electrolyte solutions under the influence of temperature, magnetic field and surface material by means of determining the electrical capacity of the liquid and the quality factor of the anti-resonant circuit in the frequency range from 1 kHz to 3000 kHz. The condenser plates in different types of electrochemical cells are placed one in front of the other, each at a distance of more than 5 cm, or relative to each other in parallel planes, or in one plane in which case the liquid is located on the condenser plates. The current density on the plates in various cells ranged from 10 to 100 nA/cm2. When measuring the electrical capacity, the voltage applied to the plates was reduced in proportion to the increase in the frequency of oscillator. The apparatus allows us to increase the dynamic range of the signal change from an electrochemical cell, reduce the impact of measurements on the structure of liquids, and also evaluate the direction and extent of changes in the structure of water and aqueous solutions under various external influences. Criteria are proposed for evaluating the structure of fluids.

  17. 75 FR 2552 - NIH State-of-the-Science Conference: Enhancing Use and Quality of Colorectal Cancer Screening

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health NIH State-of-the-Science Conference: Enhancing Use and Quality of Colorectal Cancer Screening Notice is hereby given by the National Institutes of Health (NIH) of the ``NIH State-of-the-Science...

  18. A Guide to State-Level Policies, Practices, and Procedures: Enhancing Employment Opportunities for Older Workers. Training and Employment Program.

    ERIC Educational Resources Information Center

    Alegria, Fernando L., Jr.

    This guide is intended for use by state officials as a guide to state policies, practices, and procedures that enhance employment opportunities for older workers. An executive summary highlights the problems--labor shortages and the strain on the retirement system--and a remedy--staying on the job longer. Examples of policies, practices, and…

  19. Excited-state dynamics of protonated retinal Schiff base in solution

    SciTech Connect

    Logunov, S.L.; Li, S.; El-Sayed, M.A.

    1996-11-21

    The dynamics of all-trans and 13-cis retinal protonated Schiff base (RPSB) were studied in different solvents by means of picosecond transient spectroscopy. The decay time of the excited state absorption was found to be wavelength dependent due to the contribution of the faster decay of stimulated emission. The stimulated emission has a lifetime of a 2.5-4 ps while the excited state absorption decay is biexponential with lifetimes of 2.5-4 and 10-12 ps. The fluorescence quantum yield is strongly temperature dependent but viscosity has a small effect on both excited-state lifetime and fluorescence quantum yield. This leads to the conclusion that there is a {approx}600 cm{sup -1} barrier in the excited-state which results from intramolecular electronic factors and not from the solvent viscosity. The comparison of these results with those for the retinal in rhodopsin and bacteriorhodopsin is discussed in terms of the protein catalysis for the retinal photoisomerization. 31 refs., 8 figs., 2 tabs.

  20. Indiana State University Professional Development School Partnership: Systemic, Symbiotic, and Solution-Oriented

    ERIC Educational Resources Information Center

    Libler, Rebecca

    2010-01-01

    The Indiana State University Professional Development Schools (ISU PDS) Partnership sprang from the convergence of two strong needs: (1) the need for real life practice in the way of extended clinical experiences for teacher education students in schools of practice; and (2) the need on the part of the schools in the community to have access to…

  1. Functional Coherence in the State Education Agency: A Structure for Performance Management. Solutions. Issue No. 4

    ERIC Educational Resources Information Center

    Redding, Sam; Nafziger, Dean

    2013-01-01

    The purpose of the state education agency (SEA) is to focus the entire education system on helping students become capable in college and career in an increasingly complex world. One of the most vexing problems facing SEAs today is how to meet increasing demands for performance while adjusting to significant resource reductions. Meeting that…

  2. Analytical steady-state solutions for water-limited cropping systems using saline irrigation water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems mod...

  3. Charters as a Solution?: So Far, States and Districts Have Opted for Anything But

    ERIC Educational Resources Information Center

    Smith, Nelson

    2007-01-01

    "Reopening the school as a public charter school" is Option #1 on the list of NCLB's restructuring alternatives for failing schools. But this has not proved a popular choice. NCLB made the bold assumption that states and districts would voluntarily turn over the reins to charter operators. The authors of the legislation must have thought, with so…

  4. Solutions to locoweed poisoning in New Mexico and the Western United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A collaborative locoweed research effort between New Mexico State University and the USDA/ARS Poison Plant Lab was initiated in 1990 as a result of a “grass root” producer effort and a congressional appropriation, thanks to the efforts of NM Congressman Joe Skeen. A symposium was held at the SRM an...

  5. States' Perspectives on Waivers: Relief from NCLB, Concern about Long-Term Solutions

    ERIC Educational Resources Information Center

    McMurrer, Jennifer; Yoshioka, Nanami

    2013-01-01

    On February 9, 2012, U.S. Secretary of Education Arne Duncan granted 10 states waivers of key accountability requirements of the Elementary and Secondary Education Act (ESEA), as amended by the No Child Left Behind (NCLB) Act. One year later, applications for this ESEA flexibility, also known as NCLB waivers, had been approved for an additional 24…

  6. Singularity-free solutions for anisotropic charged fluids with Chaplygin equation of state

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Ray, Saibal; Jafry, Abdul Kayum; Chakraborty, Kausik

    2010-11-01

    We extend the Krori-Barua analysis of the static, spherically symmetric, Einstein-Maxwell field equations and consider charged fluid sources with anisotropic stresses. The inclusion of a new variable (tangential pressure) allows the use of a nonlinear, Chaplygin-type equation of state with coefficients fixed by the matching conditions at the boundary of the source. Some physical features are briefly discussed.

  7. Enhancement in Steady State and Dynamic Performance of Direct Torque Control Induction Motor Drive

    NASA Astrophysics Data System (ADS)

    Singh, Bhoopendra; Jain, Shailendra; Dwivedi, Sanjeet

    2013-09-01

    An enhancement in dynamic performance of a traditional DTC drive can be achieved by a robust speed control algorithm while the steady state performance depends upon the switching strategy selected for minimization of torque ripples and an efficient flux control loop. In this paper a new torque ripple reduction technique with a modified look up table incorporating a larger number of synthesized non zero active voltage vectors is utilized to overcome the limitations of the conventionally controlled DTC drive. A fuzzy logic based speed controller and a low pass filter with tunable cutoff frequency for flux estimation is proposed in this paper. The proposed study is investigated through simulation and experimentally validated on a test drive.

  8. Tracking Pertussis and Evaluating Control Measures through Enhanced Pertussis Surveillance, Emerging Infections Program, United States

    PubMed Central

    Baumbach, Joan; Cieslak, Paul R.

    2015-01-01

    Despite high coverage with pertussis-containing vaccines, pertussis remains endemic to the United States. There have been increases in reported cases in recent years, punctuated by striking epidemics and shifting epidemiology, both of which raise questions about current policies regarding its prevention and control. Limited data on pertussis reported through the National Notifiable Disease Surveillance System have proved insufficient to answer these questions. To address shortcomings of national pertussis data, the Emerging Infections Program at the US Centers for Disease Control and Prevention launched Enhanced Pertussis Surveillance (EPS), which is characterized by systematic case ascertainment, augmented data collection, and collection of Bordetella pertussis isolates. Data collected through EPS have been instrumental in understanding the rapidly evolving epidemiology and molecular epidemiology of pertussis and have contributed essential information regarding pertussis vaccines. EPS also serves as a platform for conducting critical and timely evaluations of pertussis prevention and control strategies, including targeting of vaccinations and antimicrobial prophylaxis. PMID:26291475

  9. The frequency response of dynamic friction: Enhanced rate-and-state models

    NASA Astrophysics Data System (ADS)

    Cabboi, A.; Putelat, T.; Woodhouse, J.

    2016-07-01

    The prediction and control of friction-induced vibration requires a sufficiently accurate constitutive law for dynamic friction at the sliding interface: for linearised stability analysis, this requirement takes the form of a frictional frequency response function. Systematic measurements of this frictional frequency response function are presented for small samples of nylon and polycarbonate sliding against a glass disc. Previous efforts to explain such measurements from a theoretical model have failed, but an enhanced rate-and-state model is presented which is shown to match the measurements remarkably well. The tested parameter space covers a range of normal forces (10-50 N), of sliding speeds (1-10 mm/s) and frequencies (100-2000 Hz). The key new ingredient in the model is the inclusion of contact stiffness to take into account elastic deformations near the interface. A systematic methodology is presented to discriminate among possible variants of the model, and then to identify the model parameter values.

  10. Heterogeneity of intracellular polymer storage states in enhanced biological phosphorus removal (EBPR)--observation and modeling.

    PubMed

    Bucci, Vanni; Majed, Nehreen; Hellweger, Ferdi L; Gu, April Z

    2012-03-20

    A number of agent-based models (ABMs) for biological wastewater treatment processes have been developed, but their skill in predicting heterogeneity of intracellular storage states has not been tested against observations due to the lack of analytical methods for measuring single-cell intracellular properties. Further, several mechanisms can produce and maintain heterogeneity (e.g., different histories, uneven division) and their relative importance has not been explored. This article presents an ABM for the enhanced biological phosphorus removal (EBPR) treatment process that resolves heterogeneity in three intracellular polymer storage compounds (i.e., polyphosphate, polyhydroxybutyrate, and glycogen) in three functional microbial populations (i.e., polyphosphate-accumulating, glycogen-accumulating, and ordinary heterotrophic organisms). Model predicted distributions were compared to those based on single-cell estimates obtained using a Raman microscopy method for a laboratory-scale sequencing batch reactor (SBR) system. The model can reproduce many features of the observed heterogeneity. Two methods for introducing heterogeneity were evaluated. First, biological variability in individual cell behavior was simulated by randomizing model parameters (e.g., maximum acetate uptake rate) at division. This method produced the best fit to the data. An optimization algorithm was used to determine the best variability (i.e., coefficient of variance) for each parameter, which suggests large variability in acetate uptake. Second, biological variability in individual cell states was simulated by randomizing state variables (e.g., internal nutrient) at division, which was not able to maintain heterogeneity because the memory in the internal states is too short. These results demonstrate the ability of ABM to predict heterogeneity and provide insights into the factors that contribute to it. Comparison of the ABM with an equivalent population-level model illustrates the effect

  11. Heterogeneity of intracellular polymer storage states in enhanced biological phosphorus removal (EBPR)--observation and modeling.

    PubMed

    Bucci, Vanni; Majed, Nehreen; Hellweger, Ferdi L; Gu, April Z

    2012-03-20

    A number of agent-based models (ABMs) for biological wastewater treatment processes have been developed, but their skill in predicting heterogeneity of intracellular storage states has not been tested against observations due to the lack of analytical methods for measuring single-cell intracellular properties. Further, several mechanisms can produce and maintain heterogeneity (e.g., different histories, uneven division) and their relative importance has not been explored. This article presents an ABM for the enhanced biological phosphorus removal (EBPR) treatment process that resolves heterogeneity in three intracellular polymer storage compounds (i.e., polyphosphate, polyhydroxybutyrate, and glycogen) in three functional microbial populations (i.e., polyphosphate-accumulating, glycogen-accumulating, and ordinary heterotrophic organisms). Model predicted distributions were compared to those based on single-cell estimates obtained using a Raman microscopy method for a laboratory-scale sequencing batch reactor (SBR) system. The model can reproduce many features of the observed heterogeneity. Two methods for introducing heterogeneity were evaluated. First, biological variability in individual cell behavior was simulated by randomizing model parameters (e.g., maximum acetate uptake rate) at division. This method produced the best fit to the data. An optimization algorithm was used to determine the best variability (i.e., coefficient of variance) for each parameter, which suggests large variability in acetate uptake. Second, biological variability in individual cell states was simulated by randomizing state variables (e.g., internal nutrient) at division, which was not able to maintain heterogeneity because the memory in the internal states is too short. These results demonstrate the ability of ABM to predict heterogeneity and provide insights into the factors that contribute to it. Comparison of the ABM with an equivalent population-level model illustrates the effect

  12. Erosional Control of Orogenesis: Approximate Analytical Solution for a Two-Sided, Frictional Orogenic Wedge at Steady State

    NASA Astrophysics Data System (ADS)

    Whipple, K.; Meade, B.

    2002-12-01

    The recognition of a dynamic coupling among climate, erosion and tectonics is arguably one of the most exciting discoveries in the last 20 years. Numerical simulations using coupled thermo-mechanical and surface process models have been most influential. However, analyses to date leave the strength of the coupling between climate and tectonics uncertain. Can an intensification of erosion induce a sufficiently strong increase in rock uplift rate that steady-state relief is increased rather than reduced? In addition, it has remained unclear whether the details of the erosion processes are important to the geodynamic evolution of the orogen, and if so, how they come into play. We present an approximate analytical solution for two-sided orogenic wedges obeying a frictional rheology, and in a condition of flux steady state, that makes explicit the nature and sensitivity of the coupling between climate and rock uplift rate. A closed-form solution for the inter-relations among steady-state orogen width, rock uplift rate, patterns of internal deformation, and climate is found by combining (1) a statement of mass balance, (2) the geometry dictated by critical taper theory for a frictional wedge, (3) relations for equilibrium topography consistent with both the tapered wedge geometry and with erosion rates necessary to satisfy the mass balance condition, and (4) a kinematic solution for internal deformation. An approximate relation for the timescale of adjustment to a new steady state following a step-function change in climatic or tectonic conditions is also found. We make the simplifying assumption that the topographic taper is invariant with orogen width, tectonic influx rate, climate, and time. Erosion rates are assumed to be dictated by the bedrock channel network and are described by the stream-power model of bedrock channel incision. Erosional efficiency (and its spatial distribution) is shown to control steady-state orogen width, crest elevation, crustal thickness

  13. Resonance Raman characterization of different forms of ground-state 8-bromo-7-hydroxyquinoline caged acetate in aqueous solutions.

    PubMed

    An, Hui-Ying; Ma, Chensheng; Nganga, Jameil L; Zhu, Yue; Dore, Timothy M; Phillips, David Lee

    2009-03-26

    The 8-bromo-7-hydroxyquinolinyl group (BHQ) is a derivative of 7-hydroxyquinoline (7-HQ) and BHQ molecules coexisting as different forms in aqueous solution. Absorption and resonance Raman spectroscopic methods were used to examine 8-bromo-7-hydroxyquinoline protected acetate (BHQ-OAc) in acetonitrile (MeCN), H(2)O/MeCN (60:40, v/v, pH 6 approximately 7), and NaOH-H(2)O/MeCN (60:40, v/v, pH 11 approximately 12) to obtain a better characterization of the forms of the ground-state species of BHQ-OAc in aqueous solutions and to examine their properties. The absorption spectra of BHQ-OAc in water show no absorption bands of the tautomeric species unlike the strong band at about 400 nm observed for the tautomeric form in 7-HQ aqueous solution. The resonance Raman spectra in conjunction with Raman spectra predicted from density functional theory (DFT) calculations reveal the observation of a double Raman band system characteristic of the neutral form (the nominal C=C ring stretching, C-N stretching, and O-H bending modes at 1564 and 1607 cm(-1)) and a single Raman band diagnostic of the enol-deprotonated anionic form (the nominal C=C ring, C-N, and C-O(-) stretching modes in the 1593 cm(-1) region). These results suggest that the neutral form of BHQ-OAc is the major species in neutral aqueous solution. There is a modest increase in the amount of the anionic form and a big decrease in the amount of the tautomeric form of the molecules for BHQ-OAc compared to 7-HQ in neutral aqueous solution. The presence of the 8-bromo group and/or competitive hydrogen bonding that hinder the formation and transfer process of a BHQ-OAc-water cyclic complex may be responsible for this large substituent effect. PMID:19296708

  14. Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 (13C) and hydrogen-1 (1H) nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thorn, Kevin A.; Folan, Daniel W.; MacCarthy, Patrick

    1989-01-01

    Standard and reference samples of the International Humic Substances Society have been characterized by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance (NMR) spectrometry. Samples included the Suwannee River, soil, and peat standard fulvic and humic acids, the Leonardite standard humic acid, the Nordic aquatic reference fulvic and humic acids, and the Summit Hill soil reference humic acid. Aqueous-solution carbon-13 NMR analyses included the measurement of spin-lattice relaxation times, measurement of nuclear Overhauser enhancement factors, measurement of quantitative carbon distributions, recording of attached proton test spectra, and recording of spectra under nonquantitative conditions. Distortionless enhancement by polarization transfer carbon-13 NMR spectra also were recorded on the Suwannee River fulvic acid in deuterated dimethyl sulfoxide. Hydrogen-1 NMR spectra were recorded on sodium salts of the samples in deuterium oxide. The carbon aromaticities of the samples ranged from 0.24 for the Suwannee River fulvic acid to 0.58 for the Leonardite humic acid.

  15. Potato flour mediated solid-state fermentation for the enhanced production of Bacillus thuringiensis-toxin.

    PubMed

    Smitha, Robinson Babysarojam; Jisha, Veloorvalappil Narayanan; Pradeep, Selvanesan; Josh, Moolakkariyil Sarath; Benjamin, Sailas

    2013-11-01

    In this study, we explored the efficacy of raw potato flour (PF) as supplement to the conventional LB medium (LB control, designated as M1) for enhancing the concomitant production of endospores and δ-endotoxin from Bacillus thuringiensis subsp. kurstaki by solid-state fermentation (SSF). Of different concentrations and combinations of media tested, 10% (w/v) PF supplemented LB medium (M2) was found as the best source for the maximum yield of toxin. After 12 h submerged fermentation (SmF) at 37°C and 125 rpm, M2 was made into a wet-solid matter for SSF by removing the supernatant (1000 ×g, 10 min); the resultant pellet subsequently incubated statically (37°C) for the production of B. thuringiensis subsp. kurstaki toxin (Btk-toxin). In comparison to M1, yield of δ-endotoxin purified by sucrose density gradient centrifugation method from M2 was about 6-fold higher (53% recovery). This maximum yield from M2 was obtained at 48 h (as against 72 h from M1), thus the gestation period of M2 was reduced by 24 h with higher yield. In addition to the quantitative data, qualitative photomicrographs taken by image analyzer, scanning electron and fluorescent microscopes and digital camera showed physical evidences for the upper hand of SSF over conventional SmF for the enhanced production of Btk-toxin. SDS-PAGE image of the purified δ-endotoxin showed three major fractions with apparent MWs 66, 45 and 30 kDa. Briefly, if low-cost agricultural products like PF is used as supplement to LB, by SSF strategy, production of Btk-toxin could be enhanced to 6-fold in short gestation time without losing its entomotoxicity efficiency.

  16. Sensitivity-enhanced solid-state NMR detection of expansin's target in plant cell walls

    SciTech Connect

    Wang, Tuo; Park, Yong Bum; Caporini, Marc A.; Rosay, Melanie; Zhong, Linghao; Cosgrove, Daniel J.; Hong, Mei

    2013-08-29

    Structure determination of protein binding to noncrystalline macromolecular assemblies such as plant cell walls (CWs) poses a significant structural biology challenge. CWs are loosened during growth by expansin proteins, which weaken the noncovalent network formed by cellulose, hemicellulose, and pectins, but the CW target of expansins has remained elusive because of the minute amount of the protein required for activity and the complex nature of the CW. Using solid-state NMR spectroscopy, combined with sensitivity-enhancing dynamic nuclear polarization (DNP) and differential isotopic labeling of expansin and polysaccharides, we have now determined the functional binding target of expansin in the Arabidopsis thaliana CW. By transferring the electron polarization of a biradical dopant to the nuclei, DNP allowed selective detection of 13C spin diffusion from trace concentrations of 13C, 15N-labeled expansin in the CW to nearby polysaccharides. From the spin diffusion data of wild-type and mutant expansins, we conclude that to loosen the CW, expansin binds highly specific cellulose domains enriched in xyloglucan, whereas more abundant binding to pectins is unrelated to activity. Molecular dynamics simulations indicate short 13C-13C distances of 4–6 Å between a hydrophobic surface of the cellulose microfibril and an aromatic motif on the expansin surface, consistent with the observed NMR signals. DNP-enhanced 2D 13C correlation spectra further reveal that the expansin-bound cellulose has altered conformation and is enriched in xyloglucan, thus providing unique insight into the mechanism of CW loosening. DNP-enhanced NMR provides a powerful, generalizable approach for investigating protein binding to complex macromolecular targets.

  17. Sensitivity-enhanced solid-state NMR detection of expansin's target in plant cell walls.

    PubMed

    Wang, Tuo; Park, Yong Bum; Caporini, Marc A; Rosay, Melanie; Zhong, Linghao; Cosgrove, Daniel J; Hong, Mei

    2013-10-01

    Structure determination of protein binding to noncrystalline macromolecular assemblies such as plant cell walls (CWs) poses a significant structural biology challenge. CWs are loosened during growth by expansin proteins, which weaken the noncovalent network formed by cellulose, hemicellulose, and pectins, but the CW target of expansins has remained elusive because of the minute amount of the protein required for activity and the complex nature of the CW. Using solid-state NMR spectroscopy, combined with sensitivity-enhancing dynamic nuclear polarization (DNP) and differential isotopic labeling of expansin and polysaccharides, we have now determined the functional binding target of expansin in the Arabidopsis thaliana CW. By transferring the electron polarization of a biradical dopant to the nuclei, DNP allowed selective detection of (13)C spin diffusion from trace concentrations of (13)C, (15)N-labeled expansin in the CW to nearby polysaccharides. From the spin diffusion data of wild-type and mutant expansins, we conclude that to loosen the CW, expansin binds highly specific cellulose domains enriched in xyloglucan, whereas more abundant binding to pectins is unrelated to activity. Molecular dynamics simulations indicate short (13)C-(13)C distances of 4-6 Å between a hydrophobic surface of the cellulose microfibril and an aromatic motif on the expansin surface, consistent with the observed NMR signals. DNP-enhanced 2D (13)C correlation spectra further reveal that the expansin-bound cellulose has altered conformation and is enriched in xyloglucan, thus providing unique insight into the mechanism of CW loosening. DNP-enhanced NMR provides a powerful, generalizable approach for investigating protein binding to complex macromolecular targets.

  18. Enhanced solution velocity between dark and light areas with horizontal tubes and triangular prism baffles to improve microalgal growth in a flat-panel photo-bioreactor.

    PubMed

    Yang, Zongbo; Cheng, Jun; Xu, Xiaodan; Zhou, Junhu; Cen, Kefa

    2016-07-01

    Novel horizontal tubes and triangular prism (HTTP) baffles that generate flow vortices were developed to increase solution velocity between dark and light areas and thus improve microalgal growth in a flat-panel photo-bioreactor. Solution velocity, mass-transfer coefficient, and mixing time were measured with a particle-imaging velocimeter, dissolved oxygen probes, and pH probes. The solution mass-transfer coefficient increased by 30% and mixing time decreased by 21% when the HTTP baffles were used. The solution velocity between dark and light areas increased from ∼0.9cm/s to ∼3.5cm/s, resulting in a decreased dark-light cycle period to one-fourth. This enhanced flashing light effect with the HTTP baffles dramatically increased microalgae biomass yield by 70% in the flat-panel photo-bioreactor. PMID:27038260

  19. Enhanced photocatalytic degradation of 2-propanol over macroporous GaN/ZnO solid solution prepared by a novel sol-gel method

    SciTech Connect

    Wang, Lizhong; Ouyang, Shuxin; Ren, Bofan; Wang, Defa; Ye, Jinhua

    2015-10-01

    Macroporous GaN/ZnO solid solution photocatalyst is synthesized through a novel sol-gel method under mild conditions. The performance of as-synthesized solid solution photocatalyst is evaluated for decomposition of gaseous 2-propanol (IPA). It is found that due to enhancement in both the adsorption to gaseous IPA and the absorbance to visible light, the porous GaN/ZnO solid solution exhibits a good photocatalytic performance for IPA decomposition. Moreover, the mechanism for photocatalytic degradation IPA over porous GaN/ZnO solid solution is also investigated in comparison with those for the two end materials ZnO and GaN. The trapping effects with different scavengers prove that both the photoexcited electrons and holes affect the IPA photodegradation process, simultaneously.

  20. Enhancing behavioral science education at the Ohio State University College of Medicine.

    PubMed

    Post, Douglas M; Stone, Linda C; Knutson, Douglas J; Gutierrez, Tamara L; Sari, Firuzan; Hudson, William A

    2008-01-01

    The social and behavioral sciences play key roles in patient health outcomes. Given this reality, successful development of social and behavioral science curricula in medical education is critically important to the quality of patients' lives and the effectiveness of health care delivery systems. The Institute of Medicine, in a recent report, recommended that medical schools enhance their curricula in these areas and identified four institutions as "exemplars" of social and behavioral science education. The authors describe an ongoing curriculum development and improvement process that produced one such exemplary program at The Ohio State University College of Medicine. The authors provide a historical perspective on behavioral science education, discuss issues that led to curricular change, and describe the principles and processes used to implement reform. Critical factors underlying positive change are addressed: increase active learning, recruit a core group of small-group facilitators who are primary care physicians, diversify teaching methods, support student-directed educational initiatives, enhance student-teacher relationships, centralize course administration, obtain funding, implement a faculty development program, and apply curriculum quality improvement methods. Outcome data from evaluations completed by both students and small-group physician faculty are presented, and future directions regarding further revision are outlined. The authors believe that the strategies they describe can be applied at other institutions and assist behavioral science educators who may experience the challenges typically encountered in this important field of medical education.

  1. Enhanced conduction band density of states in intermetallic EuTSi3 (T = Rh, Ir)

    NASA Astrophysics Data System (ADS)

    Maurya, Arvind; Bonville, P.; Thamizhavel, A.; Dhar, S. K.

    2015-09-01

    We report on the physical properties of single crystalline EuRhSi3 and polycrystalline EuIrSi3, inferred from magnetization, electrical transport, heat capacity and 151Eu Mössbauer spectroscopy. These previously known compounds crystallise in the tetragonal BaNiSn3-type structure. The single crystal magnetization in EuRhSi3 has a strongly anisotropic behaviour at 2 K with a spin-flop field of 13 T, and we present a model of these magnetic properties which allows the exchange constants to be determined. In both compounds, specific heat shows the presence of a cascade of two close transitions near 50 K, and the 151Eu Mössbauer spectra demonstrate that the intermediate phase has an incommensurate amplitude modulated structure. We find anomalously large values, with respect to other members of the series, for the RKKY Néel temperature, for the spin-flop field (13 T), for the spin-wave gap (≃ 20-25 K) inferred from both resistivity and specific heat data, for the spin-disorder resistivity in EuIrSi3 (≃ 240 μ Ω cm) and for the saturated hyperfine field (52 T). The enhanced values of the quantities that depend on the electronic density of states at the Fermi level, imply that the latter must be strongly enhanced in these two materials. EuIrSi3 exhibits a giant magnetoresistance ratio, with values exceeding 600% at 2 K in a field of 14 T.

  2. Urban enhancement of PM10 bioaerosol tracers relative to background locations in the Midwestern United States

    NASA Astrophysics Data System (ADS)

    Rathnayake, Chathurika M.; Metwali, Nervana; Baker, Zach; Jayarathne, Thilina; Kostle, Pamela A.; Thorne, Peter S.; O'Shaughnessy, Patrick T.; Stone, Elizabeth A.

    2016-05-01

    Bioaerosols are well-known immune-active particles that exacerbate respiratory diseases. Human exposures to bioaerosols and their resultant health impacts depend on their ambient concentrations, seasonal and spatial variation, and copollutants, which are not yet widely characterized. In this study, chemical and biological tracers of bioaerosols were quantified in respirable particulate matter (PM10) collected at three urban and three background sites in the Midwestern United States across four seasons in 2012. Endotoxins from Gram-negative bacteria (and a few Gram-positive bacteria), water-soluble proteins, and tracers for fungal spores (fungal glucans, arabitol, and mannitol) were ubiquitous and showed significant seasonal variation and dependence on temperature. Fungal spores were elevated in spring and peaked in summer, following the seasonal growing cycle, while endotoxins peaked in autumn during the row crop harvesting season. Paired comparisons of bioaerosols in urban and background sites revealed significant urban enhancements in PM10, fungal glucans, endotoxins, and water-soluble proteins relative to background locations, such that urban populations have a greater outdoor exposure to bioaerosols. These bioaerosols contribute, in part, to the urban excesses in PM10. Higher bioaerosol mass fractions in urban areas relative to background sites indicate that urban areas serve as a source of bioaerosols. Similar urban enhancements in water-soluble calcium and its correlation with bioaerosol tracers point toward windblown soil as an important source of bioaerosols in urban areas.

  3. Use of a Measure of Reading Comprehension to Enhance Prediction on the State High Stakes Assessment

    PubMed Central

    Shapiro, Edward S.; Solari, Emily; Petscher, Yaacov

    2015-01-01

    The current study examined the diagnostic accuracy of two screening measures of risk for future difficulties in reading comprehension, as well as the degree to which adding a screening measure of reading comprehension enhanced the prediction of Oral Reading Fluency to outcomes of student reading performance on the state high stakes assessment for grades 3 through 5. Data from fall and winter assessments of the DIBELS Oral Reading Fluency (DORF) and 4Sight Benchmark Assessment (4Sight) measures along with outcomes on the Pennsylvania System of School Assessment (PSSA) across a total of 1000 students from 6 schools were examined using indices of diagnostic efficiency, ROC curve, and logistic regression analyses. Results showed that the addition of a measure of reading comprehension (4Sight) to DORF enhanced the decision making process for identifying students at risk for reading difficulties, especially for those students at higher elementary grades and those who achieved benchmark levels on the DORF. Although DORF alone showed a good level of prediction to the statewide assessment, the combination of the DORF plus 4Sight measures resulted consistently in the best predictive outcomes. Suggestions are made to consider alternative cut points for the DORF and 4Sight measures. PMID:26347390

  4. Mg(OH)2 Supported Nanoscale Zero Valent Iron Enhancing the Removal of Pb(II) from Aqueous Solution.

    PubMed

    Liu, Minghui; Wang, Yonghao; Chen, Luntai; Zhang, Yan; Lin, Zhang

    2015-04-22

    In this article, a novel composite (Mg(OH)2 supported nanoscale zerovalent iron (denoted as nZVI@Mg(OH)2) was prepared and characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy method. The morphology analysis revealed that Mg(OH)2 appeared as self-supported flower-like spheres, and nano Fe0 particles were uniformly immobilized on the surface of their "flower petals", thus aggregation of Fe0 particles was minimized. Then the Pb(II) removal performance was tested by batch experiments. The composite presented exceptional removal capacity (1986.6 mg/g) compared with Mg(OH)2 and nanoscale zerovalent iron due to the synergistic effect. Mechanisms were also explored by a comparative study of the phase, morphology, and surface valence state of composite before and after reaction, indicating that at least three paths are involved in the synergistic removal process: (1) Pb(II) adsorption by Mg(OH)2 (companied with ion exchange reaction); (2) Pb(II) reduction to Pb0 by nanoscale zerovalent iron; and (3) Pb(II) precipitation as Pb(OH)2. The hydroxies provided by Mg(OH)2 can dramatically promote the role of nanoscale zerovalent iron as reducer, thus greatly enhancing the whole Pb(II) sequestration process. The excellent performance shown in our research potentially provides an alternative technique for Pb(II) pollution treatment.

  5. The Pursuit of K: Reflections on the Current State-of-the-Art in Stress Intensity Factor Solutions for Practical Aerospace Applications

    NASA Technical Reports Server (NTRS)

    CraigMcClung, R.; Lee, Yi-Der; Cardinal, Joseph W.; Guo, Yajun

    2012-01-01

    The elastic stress intensity factor (SIF, commonly denoted as K) is the foundation of practical fracture mechanics (FM) analysis for aircraft structures. This single parameter describes the first-order effects of stress magnitude and distribution as well as the geometry of both structure/component and crack. Hence, the calculation of K is often the most significant step in fatigue analysis based on FM. This presentation will provide several reflections on the current state-of-the-art in SIF solution methods used for practical aerospace applications, including a brief historical perspective, descriptions of some recent and ongoing advances, and comments on some remaining challenges. Newman and Raju made significant early contributions to practical structural analysis by developing closed-form SIF equations for surface and corner cracks in simplified geometries, often based on empirical fits of finite element (FE) solutions. Those solutions (and others like them) were sometimes revised as new analyses were conducted or limitations discovered. The foundational solutions have exhibited striking longevity, despite the relatively "coarse" FE models employed many decades ago. However, in recent years, the accumulation of different generations of solutions for the same nominal geometry has led to some confusion (which solution is correct?), and steady increases in computational capabilities have facilitated the discovery of inaccuracies in some (not all!) of the legacy solutions. Some examples of problems and solutions are presented and discussed, including the challenge of maintaining consistency with legacy design applications. As computational power has increased, the prospect of calculating large numbers of SIF solutions for specific complex geometries with advanced numerical methods has grown more attractive. Fawaz and Andersson, for example, have been generating literally millions of new SIF solutions for different combinations of multiple cracks under simplified

  6. Loss-tolerant state engineering for quantum-enhanced metrology via the reverse Hong-Ou-Mandel effect.

    PubMed

    Ulanov, Alexander E; Fedorov, Ilya A; Sychev, Demid; Grangier, Philippe; Lvovsky, A I

    2016-01-01

    Highly entangled quantum states, shared by remote parties, are vital for quantum communications and metrology. Particularly promising are the N00N states-entangled N-photon wavepackets delocalized between two different locations-which outperform coherent states in measurement sensitivity. However, these states are notoriously vulnerable to losses, making them difficult to both share them between remote locations and recombine in order to exploit interference effects. Here we address this challenge by utilizing the reverse Hong-Ou-Mandel effect to prepare a high-fidelity two-photon N00N state shared between two parties connected by a lossy optical medium. We measure the prepared state by two-mode homodyne tomography, thereby demonstrating that the enhanced phase sensitivity can be exploited without recombining the two parts of the N00N state. Finally, we demonstrate the application of our method to remotely prepare superpositions of coherent states, known as Schrödinger's cat states. PMID:27324115

  7. Loss-tolerant state engineering for quantum-enhanced metrology via the reverse Hong-Ou-Mandel effect.

    PubMed

    Ulanov, Alexander E; Fedorov, Ilya A; Sychev, Demid; Grangier, Philippe; Lvovsky, A I

    2016-06-21

    Highly entangled quantum states, shared by remote parties, are vital for quantum communications and metrology. Particularly promising are the N00N states-entangled N-photon wavepackets delocalized between two different locations-which outperform coherent states in measurement sensitivity. However, these states are notoriously vulnerable to losses, making them difficult to both share them between remote locations and recombine in order to exploit interference effects. Here we address this challenge by utilizing the reverse Hong-Ou-Mandel effect to prepare a high-fidelity two-photon N00N state shared between two parties connected by a lossy optical medium. We measure the prepared state by two-mode homodyne tomography, thereby demonstrating that the enhanced phase sensitivity can be exploited without recombining the two parts of the N00N state. Finally, we demonstrate the application of our method to remotely prepare superpositions of coherent states, known as Schrödinger's cat states.

  8. Loss-tolerant state engineering for quantum-enhanced metrology via the reverse Hong-Ou-Mandel effect

    NASA Astrophysics Data System (ADS)

    Ulanov, Alexander E.; Fedorov, Ilya A.; Sychev, Demid; Grangier, Philippe; Lvovsky, A. I.

    2016-06-01

    Highly entangled quantum states, shared by remote parties, are vital for quantum communications and metrology. Particularly promising are the N00N states--entangled N-photon wavepackets delocalized between two different locations--which outperform coherent states in measurement sensitivity. However, these states are notoriously vulnerable to losses, making them difficult to both share them between remote locations and recombine in order to exploit interference effects. Here we address this challenge by utilizing the reverse Hong-Ou-Mandel effect to prepare a high-fidelity two-photon N00N state shared between two parties connected by a lossy optical medium. We measure the prepared state by two-mode homodyne tomography, thereby demonstrating that the enhanced phase sensitivity can be exploited without recombining the two parts of the N00N state. Finally, we demonstrate the application of our method to remotely prepare superpositions of coherent states, known as Schrödinger's cat states.

  9. Solid-State and Solution Structures of Glycinimine-Derived Lithium Enolates.

    PubMed

    Jin, Kyoung Joo; Collum, David B

    2015-11-18

    A combination of crystallographic, spectroscopic, and computational studies was applied to study the structures of lithium enolates derived from glycinimines of benzophenone and (+)-camphor. The solvents examined included toluene and toluene containing various concentrations of tetrahydrofuran, N,N,N',N'-tetramethylethylenediamine (TMEDA), (R,R)-N,N,N',N'-tetramethylcyclohexanediamine [(R,R)-TMCDA], and (S,S)-N,N,N',N'-tetramethylcyclohexanediamine [(S,S)-TMCDA]. Crystal structures show chelated monomers, symmetric disolvated dimers, S4-symmetric tetramers, and both S6- and D3d-symmetric hexamers. (6)Li NMR spectroscopic studies in conjunction with the method of continuous variations show how these species distribute in solution. Density functional theory computations offer insights into experimentally elusive details. PMID:26554898

  10. Calculated equilibria between adjacent valence states of plutonium in simple aqueous solutions

    SciTech Connect

    Sweeton, F.H.

    1981-02-01

    Equilibrium data have been taken from the literature for the oxidation of Pu/sup 3 +/ to Pu/sup 4 +/, Pu/sup 4 +/ to PuO/sub 2//sup +/ and PuO/sub 2//sup +/ to PuO/sub 2//sup 2 +/, and for the hydrolysis of these four plutonium species in dilute solutions. These data have been used to calculate the oxidation-reduction potentials (expressed as E/sub h/) at which the concentrations of the two species (including the hydrolyzed forms) in each pair are equal. These calculations cover the pH range of 0 to 13. The results indicate that there are conditions under which each species can be predominant. The solubility of PuO/sub 2/ under environmental conditions is also discussed.

  11. Shock Hugoniot and equations of states of water, castor oil, and aqueous solutions of sodium chloride, sucrose and gelatin

    NASA Astrophysics Data System (ADS)

    Gojani, A. B.; Ohtani, K.; Takayama, K.; Hosseini, S. H. R.

    2016-01-01

    This paper reports a result of experiments for the determination of reliable shock Hugoniot curves of liquids, in particular, at relatively low pressure region, which are needed to perform precise numerical simulations of shock wave/tissue interaction prior to the development of shock wave related therapeutic devices. Underwater shock waves were generated by explosions of laser ignited 10 mg silver azide pellets, which were temporally and spatially well controlled. Measuring temporal variation of shock velocities and over-pressures in caster oil, aqueous solutions of sodium chloride, sucrose and gelatin with various concentrations, we succeeded to determine shock Hugoniot curves of these liquids and hence parameters describing Tait type equations of state.

  12. Fragment-based configuration interaction wave function to calculate environmental effect on excited states in proteins and solutions

    NASA Astrophysics Data System (ADS)

    Hasegawa, Jun-ya

    2013-05-01

    Solvatochromic effect in proteins and solutions was described by a configuration interaction singles (CIS) wave function with fragment-localized molecular orbitals. Coarse-grained analysis indicated that the CI wave function can be described by local excitations and charge-transfer (CT) excitations between the chromophore and the environment. We developed an atomic-orbital direct runcated CIS code and applied the excited states of retinal chromophore in bacteriorhodopsin and MeOH environments, and those of s-trans-acrolein in water. Number of excitation operators was significantly reduced by eliminating the CT excitations between the environmental fragments. The truncated CIS wave functions reproduced the original excitation energies very well.

  13. Title III Policy: State of the States. ESEA Evaluation Brief: The English Language Acquisition, Language Enhancement, and Academic Achievement Act

    ERIC Educational Resources Information Center

    Ramsey, Andrea; O'Day, Jennifer

    2010-01-01

    "Title III Policy: State of the States" (2010) discusses state implementation of the Title III accountability requirements based on phone interviews with six state Title III Directors in the spring of 2009, interviews with six experts and university-based researchers who work on education for English Learners, and based on earlier data collected…

  14. Ionic Liquid-Enhanced Solid State Electrolyte Interface (SEI) for Lithium Sulfur Batteries

    SciTech Connect

    Zheng, Jianming; Gu, Meng; Chen, Honghao; Meduri, Praveen; Engelhard, Mark H.; Zhang, Jiguang; Liu, Jun; Xiao, Jie

    2013-05-16

    Li-S battery is a complicated system with many challenges existing before its final market penetration. While most of the reported work for Li-S batteries is focused on the cathode design, we demonstrate in this work that the anode consumption accelerated by corrosive polysulfide solution also critically determines the Li-S cell performance. To validate this hypothesis, ionic liquid (IL) N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Py14TFSI) has been employed to modify the properties of SEI layer formed on Li metal surface in Li-S batteries. It is found that the IL-enhanced passivation film on the lithium anode surface exhibits much different morphology and chemical compositions, effectively protecting lithium metal from continuous attack by soluble polysulfides. Therefore, both cell impedance and the irreversible consumption of polysulfides on lithium metal are reduced. As a result, the Coulombic efficiency and the cycling stability of Li-S batteries have been greatly improved. After 120 cycles, Li-S battery cycled in the electrolyte containing IL demonstrates a high capacity retention of 94.3% at 0.1 C rate. These results unveil another important failure mechanism for Li-S batteries and shin the light on the new approaches to improve Li-S battery performances.

  15. Interdomain orientation of cardiac troponin C characterized by paramagnetic relaxation enhancement NMR reveals a compact state.

    PubMed

    Cordina, Nicole M; Liew, Chu Kong; Gell, David A; Fajer, Piotr G; Mackay, Joel P; Brown, Louise J

    2012-09-01

    Cardiac troponin C (cTnC) is the calcium binding subunit of the troponin complex that triggers the thin filament response to calcium influx into the sarcomere. cTnC consists of two globular EF-hand domains (termed the N- and C-domains) connected by a flexible linker. While the conformation of each domain of cTnC has been thoroughly characterized through NMR studies involving either the isolated N-domain (N-cTnC) or C-domain (C-cTnC), little attention has been paid to the range of interdomain orientations possible in full-length cTnC that arises as a consequence of the flexibility of the domain linker. Flexibility in the domain linker of cTnC is essential for effective regulatory function of troponin. We have therefore utilized paramagnetic relaxation enhancement (PRE) NMR to assess the interdomain orientation of cTnC. Ensemble fitting of our interdomain PRE measurements reveals that isolated cTnC has considerable interdomain flexibility and preferentially adopts a bent conformation in solution, with a defined range of relative domain orientations.

  16. Interdomain orientation of cardiac Troponin C characterized by paramagnetic relaxation enhancement NMR reveals a compact state

    PubMed Central

    Cordina, Nicole M; Liew, Chu Kong; Gell, David A; Fajer, Piotr G; Mackay, Joel P; Brown, Louise J

    2012-01-01

    Cardiac troponin C (cTnC) is the calcium binding subunit of the troponin complex that triggers the thin filament response to calcium influx into the sarcomere. cTnC consists of two globular EF-hand domains (termed the N- and C-domains) connected by a flexible linker. While the conformation of each domain of cTnC has been thoroughly characterized through NMR studies involving either the isolated N-domain (N-cTnC) or C-domain (C-cTnC), little attention has been paid to the range of interdomain orientations possible in full-length cTnC that arises as a consequence of the flexibility of the domain linker. Flexibility in the domain linker of cTnC is essential for effective regulatory function of troponin. We have therefore utilized paramagnetic relaxation enhancement (PRE) NMR to assess the interdomain orientation of cTnC. Ensemble fitting of our interdomain PRE measurements reveals that isolated cTnC has considerable interdomain flexibility and preferentially adopts a bent conformation in solution, with a defined range of relative domain orientations. PMID:22811351

  17. High-Sensitivity Surface-Enhanced Raman Scattering (SERS) Substrate Based on a Gold Colloid Solution with a pH Change for Detection of Trace-Level Polycyclic Aromatic Hydrocarbons in Aqueous Solution.

    PubMed

    Shi, Xiaofeng; Liu, Shu; Han, Xiaohong; Ma, Jun; Jiang, Yongchao; Yu, Guifeng

    2015-05-01

    In this study, a gold colloid solution whose parameters were optimized, and without any surfactants, was developed as a surface-enhanced Raman scattering (SERS) substrate for the detection of trace-level polycyclic aromatic hydrocarbons (PAHs). A gold colloid solution with 57 nm gold particles and pH 13 was prepared to be the SERS substrate. It had impressive enhancement that was two orders of magnitude higher than that of a gold colloid solution with 57 nm gold particles and without pH change (pH 6). Even with a compact field-based Raman spectrometer, naphthalene, phenanthrene, anthracene, fluoranthene, and pyrene were detected, with limits of detection at 6.8 nM, 3.4 nM, 1.8 nM, 0.68 nM (680 pM), and 0.44 nM (440 pM), respectively. The significant enhancement was ascribed to an electromagnetic mechanism and a charge-transfer mechanism. Quantitative analyses for these five PAHs in water were also performed. The SERS intensities of PAHs were found to have good linear dependence relations with the concentrations in low concentration. This high-sensitivity, easily prepared substrate offers a promising technology for the quantitative detection of trace-level PAHs.

  18. P1 interneurons promote a persistent internal state that enhances inter-male aggression in Drosophila

    PubMed Central

    Hoopfer, Eric D; Jung, Yonil; Inagaki, Hidehiko K; Rubin, Gerald M; Anderson, David J

    2015-01-01

    How brains are hardwired to produce aggressive behavior, and how aggression circuits are related to those that mediate courtship, is not well understood. A large-scale screen for aggression-promoting neurons in Drosophila identified several independent hits that enhanced both inter-male aggression and courtship. Genetic intersections revealed that 8-10 P1 interneurons, previously thought to exclusively control male courtship, were sufficient to promote fighting. Optogenetic experiments indicated that P1 activation could promote aggression at a threshold below that required for wing extension. P1 activation in the absence of wing extension triggered persistent aggression via an internal state that could endure for minutes. High-frequency P1 activation promoted wing extension and suppressed aggression during photostimulation, whereas aggression resumed and wing extension was inhibited following photostimulation offset. Thus, P1 neuron activation promotes a latent, internal state that facilitates aggression and courtship, and controls the overt expression of these social behaviors in a threshold-dependent, inverse manner. DOI: http://dx.doi.org/10.7554/eLife.11346.001 PMID:26714106

  19. Enhanced γ -Ray Emission from Neutron Unbound States Populated in β Decay

    DOE PAGES

    Tain, J. L.; Valencia, E.; Algora, A.; Agramunt, J.; Rubio, B.; Rice, S.; Gelletly, W.; Regan, P.; Zakari-Issoufou, A. -A.; Fallot, M.; et al

    2015-08-01

    Total absorption spectroscopy was used to investigate the β -decay intensity to states above the neutron separation energy followed by γ -ray emission in 87,88Br and 94Rb. Accurate results were obtained thanks to the careful control of systematic errors. An unexpectedly large γ intensity was observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy was compared to Hauser-Feshbach model calculations. For 87Br and 88Br the branching reaches 57% and 20% respectively, and could be explained as a nuclear structuremore » effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich 94Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled introducing an enhancement of one order-of-magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proved to be correct, leads to a similar increase in the (n, γ) cross section that would have an impact on r process abundance calculations.« less

  20. Enhanced γ -Ray Emission from Neutron Unbound States Populated in β Decay

    NASA Astrophysics Data System (ADS)

    Tain, J. L.; Valencia, E.; Algora, A.; Agramunt, J.; Rubio, B.; Rice, S.; Gelletly, W.; Regan, P.; Zakari-Issoufou, A.-A.; Fallot, M.; Porta, A.; Rissanen, J.; Eronen, T.; ńystö, J.; Batist, L.; Bowry, M.; Bui, V. M.; Caballero-Folch, R.; Cano-Ott, D.; Elomaa, V.-V.; Estevez, E.; Farrelly, G. F.; Garcia, A. R.; Gomez-Hornillos, B.; Gorlychev, V.; Hakala, J.; Jordan, M. D.; Jokinen, A.; Kolhinen, V. S.; Kondev, F. G.; Martínez, T.; Mendoza, E.; Moore, I.; Penttilä, H.; Podolyák, Zs.; Reponen, M.; Sonnenschein, V.; Sonzogni, A. A.

    2015-08-01

    Total absorption spectroscopy is used to investigate the β -decay intensity to states above the neutron separation energy followed by γ -ray emission in Br,8887 and 94Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy is compared to Hauser-Feshbach model calculations. For 87Br and 88Br the γ branching reaches 57% and 20%, respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich 94Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled by introducing an enhancement of 1 order of magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proves to be correct, leads to a similar increase in the (n ,γ ) cross section that would have an impact on r process abundance calculations.