WorldWideScience

Sample records for control reaction selectivity

  1. Bond-selective control of a gas-surface reaction

    Science.gov (United States)

    Killelea, Daniel R.

    The prospect of using light to selectively control chemical reactions has tantalized chemists since the development of the laser. Unfortunately, the realization of laser-directed chemistry is frequently thwarted by the randomization of energy within the molecule through intramolecular vibrational energy distribution (IVR). However, recent results showing vibrational mode-specific reactivity on metal surfaces suggest that IVR may not always be complete for gas-surface reactions. Here, we combine molecular beam techniques and direct laser excitation to characterize the bond-specific reactivity of trideuteromethane on a Ni(111) surface. Our results reveal important details about how vibrational energy is distributed in the reactive molecule. We use a molecular beam to direct state-selected trideuteromethane (CHD 3) molecules onto a nickel single crystal sample and use the results we obtain to describe the flow of vibrational energy in the methane-surface reaction complex. We show that CHD3 molecules initially excited to v=1, J=2, K=0 of the v 1 symmetric C-H stretching mode will dissociate exclusively via C-H cleavage on Ni(111). This result highlights the localization of vibrational energy in the reaction complex, despite the presence of many energy exchange channels with the high state-density surface. We demonstrate, for the first time, highly parallel bond-selective control of a heterogeneously catalyzed reaction. We place our results in the context of recent experiments investigating IVR for molecules in both the gas phase and liquid solutions. If IVR is fast on the reaction timescale, vibrational energy would be randomly distributed throughout the nascent methane-surface reaction complex and vibrational mode-specific behavior would not occur. The short timescale of a direct gas-surface collision may explain how the exchange of energy via IVR is limited to only a small subset of the energetic configurations available to the reaction complex. This framework

  2. Optimal control of bond selectivity in unimolecular reactions

    International Nuclear Information System (INIS)

    Shi Shenghua; Rabitz, H.

    1991-01-01

    The optimal control theory approach to designing optimal fields for bond-selective unimolecular reactions is presented. A set of equations for determining the optimal fields, which will lead to the achievement of the objective of bond-selective dissociation is developed. The numerical procedure given for solving these equations requires the repeated calculation of the time propagator for the system with the time-dependent Hamiltonian. The splitting approximation combined with the fast Fourier transform algorithm is used for computing the short time propagator. As an illustrative example, a model linear triatomic molecule is treated. The model system consists of two Morse oscillators coupled via kinetic coupling. The magnitude of the dipoles of the two Morse oscillators are the same, the fundamental frequencies are almost the same, but the dissociation energies are different. The rather demanding objective under these conditions is to break the stronger bond while leaving the weaker one intact. It is encouraging that the present computational method efficiently gives rise to the optimal field, which leads to the excellent achievement of the objective of bond selective dissociation. (orig.)

  3. Chemical-Reaction-Controlled Phase Separated Drops: Formation, Size Selection, and Coarsening

    Science.gov (United States)

    Wurtz, Jean David; Lee, Chiu Fan

    2018-02-01

    Phase separation under nonequilibrium conditions is exploited by biological cells to organize their cytoplasm but remains poorly understood as a physical phenomenon. Here, we study a ternary fluid model in which phase-separating molecules can be converted into soluble molecules, and vice versa, via chemical reactions. We elucidate using analytical and simulation methods how drop size, formation, and coarsening can be controlled by the chemical reaction rates, and categorize the qualitative behavior of the system into distinct regimes. Ostwald ripening arrest occurs above critical reaction rates, demonstrating that this transition belongs entirely to the nonequilibrium regime. Our model is a minimal representation of the cell cytoplasm.

  4. Selectivity control in pd-catalyzed c-h functionalization reactions

    OpenAIRE

    Flores Gaspar, Areli

    2013-01-01

    Benzocyclobutenones are an intriguing four-membered ring ketone. In the present thesis, we have developed a new protocol for selectively preparing benzocyclobutenones through intramolecular acylation of aryl bromides via palladium catalyzed C-H bond functionalization reactions based on rac-BINAP ligand. We also found that a subtle modification on the ligand backbone lead to a new catalytic manifold for preparing configurationally-pure styrene derivatives, when using dcpp (bis-dicyclohexylphos...

  5. Controlling site selectivity in Pd-catalyzed oxidative cross-coupling reactions.

    Science.gov (United States)

    Lyons, Thomas W; Hull, Kami L; Sanford, Melanie S

    2011-03-30

    This paper presents a detailed investigation of the factors controlling site selectivity in the Pd-mediated oxidative coupling of 1,3-disubstituted and 1,2,3-trisubstituted arenes (aryl-H) with cyclometalating substrates (L~C-H). The influence of both the concentration and the steric/electronic properties of the quinone promoter are studied in detail. In addition, the effect of steric/electronic modulation of the carboxylate ligand is discussed. Finally, we demonstrate that substitution of the carboxylate for a carbonate X-type ligand leads to a complete reversal in site selectivity for many arene substrates. The origins of these trends in site selectivity are discussed in the context of the mechanism of Pd-catalyzed oxidative cross-coupling.

  6. THE HYDROVINYLATION AND RELATED REACTIONS: NEW PROTOCOLS AND CONTROL ELEMENTS IN SEARCH OF GREATER SYNTHETIC EFFICIENCY AND SELECTIVITY. (R826120)

    Science.gov (United States)

    New reaction conditions and stereochemical control elements for heterodimerization between ethylene (or propylene) and functionalized vinyl arenes are highlighted (see equation). For example, an enantioselective version of the hydrovinylation reaction uses [{(allyl)NiBr}...

  7. Substrate-Directed Catalytic Selective Chemical Reactions.

    Science.gov (United States)

    Sawano, Takahiro; Yamamoto, Hisashi

    2018-05-04

    The development of highly efficient reactions at only the desired position is one of the most important subjects in organic chemistry. Most of the reactions in current organic chemistry are reagent- or catalyst-controlled reactions, and the regio- and stereoselectivity of the reactions are determined by the inherent nature of the reagent or catalyst. In sharp contrast, substrate-directed reaction determines the selectivity of the reactions by the functional group on the substrate and can strictly distinguish sterically and electronically similar multiple reaction sites in the substrate. In this Perspective, three topics of substrate-directed reaction are mainly reviewed: (1) directing group-assisted epoxidation of alkenes, (2) ring-opening reactions of epoxides by various nucleophiles, and (3) catalytic peptide synthesis. Our newly developed synthetic methods with new ligands including hydroxamic acid derived ligands realized not only highly efficient reactions but also pinpointed reactions at the expected position, demonstrating the substrate-directed reaction as a powerful method to achieve the desired regio- and stereoselective functionalization of molecules from different viewpoints of reagent- or catalyst-controlled reactions.

  8. Global Controllability of Chemical Reactions

    OpenAIRE

    Drexler, Dániel András; Tóth, János

    2015-01-01

    Controllability of chemical reactions is an important problem in chemical engineering science. In control theory, analysis of the controllability of linear systems is well-founded, however the dynamics of chemical reactions is usually nonlinear. Global controllability properties of chemical reactions are analyzed here based on the Lie-algebra of the vector fields associated to elementary reactions. A chemical reaction is controllable almost everywhere if all the reaction rate coefficients can...

  9. [Active surveillance of adverse drug reaction in the era of big data: challenge and opportunity for control selection].

    Science.gov (United States)

    Wang, S F; Zhan, S Y

    2016-07-01

    Electronic healthcare databases have become an important source for active surveillance of drug safety in the era of big data. The traditional epidemiology research designs are needed to confirm the association between drug use and adverse events based on these datasets, and the selection of the comparative control is essential to each design. This article aims to explain the principle and application of each type of control selection, introduce the methods and parameters for method comparison, and describe the latest achievements in the batch processing of control selection, which would provide important methodological reference for the use of electronic healthcare databases to conduct post-marketing drug safety surveillance in China.

  10. Selected aspects of fusion reactions

    International Nuclear Information System (INIS)

    Lacroix, D.

    2003-01-01

    In this lecture, we present selected aspects of nuclear fusion. The importance of the initial geometry of the reaction and its relation to fusion barrier are first discussed. The effect of deformation leading to the notion of barrier distribution is then illustrated. After a brief overview of the advantages of macroscopic theories, the dynamics of nuclear system under large amplitude motion is reviewed. The di-nuclear concept is presented to understand the competition between fusion and quasi-fission. This concept is then generalized to account for the dissipative dynamics in multidimensional collective space. The last part of this lecture is devoted to new aspects encountered with radioactive beams specific properties of very extended neutron rich system, influence of pygmy or soft dipole resonances and charge exchange far from stability are discussed. (author)

  11. Rejection Positivity Predicts Trial-to-Trial Reaction Times in an Auditory Selective Attention Task: A Computational Analysis of Inhibitory Control

    Directory of Open Access Journals (Sweden)

    Sufen eChen

    2014-08-01

    Full Text Available A series of computer simulations using variants of a formal model of attention (Melara & Algom, 2003 probed the role of rejection positivity (RP, a slow-wave electroencephalographic (EEG component, in the inhibitory control of distraction. Behavioral and EEG data were recorded as participants performed auditory selective attention tasks. Simulations that modulated processes of distractor inhibition accounted well for reaction-time (RT performance, whereas those that modulated target excitation did not. A model that incorporated RP from actual EEG recordings in estimating distractor inhibition was superior in predicting changes in RT as a function of distractor salience across conditions. A model that additionally incorporated momentary fluctuations in EEG as the source of trial-to-trial variation in performance precisely predicted individual RTs within each condition. The results lend support to the linking proposition that RP controls the speed of responding to targets through the inhibitory control of distractors.

  12. Selectivity in heavy ion transfer reactions

    International Nuclear Information System (INIS)

    Boucenna, A.

    1989-01-01

    One-two-and three-nucleon stripping reactions induced by 480 MeV 12 C and by 793 MeV 16 O have been studied on 12 C, 16 O, 28 Si, 40 Ca, and 54 Fe targets. Discrete levels are fed with cross sections up to 1 mb/sr for d-transfer reactions and one and two orders of magnitude less for 2p- and 3 He-transfers, respectively. These reactions are governed by two selection rules contained in the semi-classical model of Brink: i) Large orbital final momentum states are selectively populated and ii) The most highly populated states correspond to no-flip transitions. Two-proton transfer reactions induced by 112 MeV 12 C on even Ni and Zn isotopes are found to be less selective than two-neutron transfer reactions induced by the same projectile on the same targets in a similar incident energy range. The additional collective aspects observed in the two-proton transfers are examined in view of a semiphenomenological model of two quasi-particles coupled to a triaxial asymmetric rotor. The energy of excited states is well reproduced by simple shell model calculations. Such estimates are useful in proposing spins of newly observed states, especially as the shapes of the measured angular distributions are independant of the final spin of the residual nucleus. The experimental results of two-proton and two-neutron stripping reactions and the simple shell model allow an estimate of two-body matrix elements describing the nucleon-nucleon interaction and of the Coulomb energy [fr

  13. Overview of selective photo-reaction

    International Nuclear Information System (INIS)

    Arisawa, Takashi

    1995-01-01

    Selective reaction process especially isotope separation is a key technology for the development of the technologies related to the nuclear energy. However only a few species are separated on a production scale using the conventional processes such as thermal diffusion, chemical exchange reaction and distillation for lighter isotopes, and gas centrifuge and gaseous diffusion for uranium. As these methods are based on statistical thermodynamics and have low enrichment factors, they need repetitive operations of separation with many separating units combined together. Electro-magnetic separation method known as the one with high separation factor can be applied to most of the elements, but extremely low production rate is realized, which is uneconomical. From the above point of view, much attention has been pain to the laser process. This method can be applied to either gas, liquid or solid phase, and high separation factors are basically realized only in gaseous phase. Since the beginning of the studies on isotope separation in early 1970s, many ideas have been proposed for the selective photo-reaction process such as photoionization, multiphoton dissociation and state selective chemical reaction. As a result of experimental and theoretical efforts, large scale production of some isotopes have been intended. Production of deuterium by infrared multi-photodissociation method was studied aiming at the replacement of the conventional dual temperature exchange process, and lots of experiments have been achieved intensively for the uranium enrichment. A stepwise selective photoionization method has also been studied for the isotopic separation of many elements, especially uranium enrichment. To implement the laser processes on a large scale production system, advanced performances are required not only for the tunable laser systems but also for many related technologies such as atomic/molecular source, photo-reactor and extractor of products. (author)

  14. Synthesis of Precursors of the Agalacto (Exo) Fragment of the Quartromicins via an Auxiliary-Controlled Exo-Selective Diels-Alder Reaction

    Science.gov (United States)

    Qi, Jun; Roush, William R.

    2008-01-01

    A direct synthesis of the α-hydroxyaldehyde exo-5, a precursor of the exo-spirotetronate subunit o f the quartromicins, was achieved through an exo-selective Lewis acid-catalyzed Diels-Alder reaction of dienophile 12a and diene 1. PMID:16774259

  15. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  16. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions.

    Science.gov (United States)

    Coari, Kristin M; Martin, Rebecca C; Jain, Kopal; McGown, Linda B

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  17. Plasma and controlled thermonuclear reaction

    International Nuclear Information System (INIS)

    Kapitsa, P.

    1980-01-01

    The principle and prospects are given of three methods of achieving controlled thermonuclear reaction. The original and so far most promising TOKAMAK method is presented invented in the USSR. Another method is the heating of a sphere about 1 mm in diameter from a mixture of deuterium and tritium by focused laser light from all sides. The third method consists in continuous plasma heating. A rope-like plasma discharge at a temperature of more than a million K results in the gas from microwave oscillations. The discharge is placed in a magnetic field and the ion temperature is increased by magneto-acoustic waves. A reactor is proposed operating on this principle and problems are pointed out which will have to be resolved. (M.S.)

  18. Plasma and controlled thermonuclear reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kapitsa, P

    1980-06-01

    The principle and prospects are given of three methods of achieving controlled thermonuclear reaction. The original and so far most promising TOKAMAK method is presented invented in the USSR. Another method is the heating of a sphere about 1 mm in diameter from a mixture of deuterium and tritium by focused laser light from all sides. The third method consists in continuous plasma heating. A rope-like plasma discharge at a temperature of more than a million K results in the gas from microwave oscillations. The discharge is placed in a magnetic field and the ion temperature is increased by magneto-acoustic waves. A reactor is proposed operating on this principle and problems are pointed out which will have to be resolved.

  19. Final Project Report for Grant DE-FG03-00ER54581 Selective Control of Chemical Reactions With Plasmas. Period covered: August 15, 2000 to January 31, 2004

    International Nuclear Information System (INIS)

    Anthony Muscat

    2004-01-01

    OAK-B135 This research work focused on control of the reactive species inside a plasma through measurement and manipulation of the electron energy distribution function (EEDF) and on understanding the surface reaction mechanisms on the substrate exposed to a combination of ion and atom beam sources to simulate a real plasma. A GEC chamber (Gaseous Electronic Conference Reference Cell)8 with a mass spectrometer and a Langmuir probe (LP) system were used for this research. It was found that H2 and N2 additives to an Ar plasma could effectively change the EEDF and the average electron temperature (Te). This finding provides the possibility to selectively control reaction rates in the plasma to control etching selectivity on a surface. This concept was demonstrated in Ar/N2/H2 and Ar/CH4 /H2 systems

  20. Morphological effects on the selectivity of intramolecular versus intermolecular catalytic reaction on Au nanoparticles.

    Science.gov (United States)

    Wang, Dan; Sun, Yuanmiao; Sun, Yinghui; Huang, Jing; Liang, Zhiqiang; Li, Shuzhou; Jiang, Lin

    2017-06-14

    It is hard for metal nanoparticle catalysts to control the selectivity of a catalytic reaction in a simple process. In this work, we obtain active Au nanoparticle catalysts with high selectivity for the hydrogenation reaction of aromatic nitro compounds, by simply employing spine-like Au nanoparticles. The density functional theory (DFT) calculations further elucidate that the morphological effect on thermal selectivity control is an internal key parameter to modulate the nitro hydrogenation process on the surface of Au spines. These results show that controlled morphological effects may play an important role in catalysis reactions of noble metal NPs with high selectivity.

  1. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    3. DATES COVERED (From - To) 09/23/15 - 04/22/16 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Preventing Corrosion by Controlling Cathodic Reaction...Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith

  2. Femtosecond laser control of chemical reactions

    CSIR Research Space (South Africa)

    Du Plessis, A

    2010-08-31

    Full Text Available Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable...

  3. Chemical potential and reaction electronic flux in symmetry controlled reactions.

    Science.gov (United States)

    Vogt-Geisse, Stefan; Toro-Labbé, Alejandro

    2016-07-15

    In symmetry controlled reactions, orbital degeneracies among orbitals of different symmetries can occur along a reaction coordinate. In such case Koopmans' theorem and the finite difference approximation provide a chemical potential profile with nondifferentiable points. This results in an ill-defined reaction electronic flux (REF) profile, since it is defined as the derivative of the chemical potential with respect to the reaction coordinate. To overcome this deficiency, we propose a new way for the calculation of the chemical potential based on a many orbital approach, suitable for reactions in which symmetry is preserved. This new approach gives rise to a new descriptor: symmetry adapted chemical potential (SA-CP), which is the chemical potential corresponding to a given irreducible representation of a symmetry group. A corresponding symmetry adapted reaction electronic flux (SA-REF) is also obtained. Using this approach smooth chemical potential profiles and well defined REFs are achieved. An application of SA-CP and SA-REF is presented by studying the Cs enol-keto tautomerization of thioformic acid. Two SA-REFs are obtained, JA'(ξ) and JA'' (ξ). It is found that the tautomerization proceeds via an in-plane delocalized 3-center 4-electron O-H-S hypervalent bond which is predicted to exist only in the transition state (TS) region. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  4. Versatile Dual Photoresponsive System for Precise Control of Chemical Reactions.

    Science.gov (United States)

    Xu, Can; Bing, Wei; Wang, Faming; Ren, Jinsong; Qu, Xiaogang

    2017-08-22

    A versatile method for photoregulation of chemical reactions was developed through a combination of near-infrared (NIR) and ultraviolet (UV) light sensitive materials. This regulatory effect was achieved through photoresponsive modulation of reaction temperature and pH values, two prominent factors influencing reaction kinetics. Photothermal nanomaterial graphene oxide (GO) and photobase reagent malachite green carbinol base (MGCB) were selected for temperature and pH regulation, respectively. Using nanocatalyst- and enzyme-mediated chemical reactions as model systems, we demonstrated the feasibility and high efficiency of this method. In addition, a photoresponsive, multifunctional "Band-aid"-like hydrogel platform was presented for programmable wound healing. Overall, this simple, efficient, and reversible system was found to be effective for controlling a wide variety of chemical reactions. Our work may provide a method for remote and sustainable control over chemical reactions for industrial and biomedical applications.

  5. Directing reaction pathways by catalyst active-site selection using self-assembled monolayers.

    Science.gov (United States)

    Pang, Simon H; Schoenbaum, Carolyn A; Schwartz, Daniel K; Medlin, J Will

    2013-01-01

    One key route for controlling reaction selectivity in heterogeneous catalysis is to prepare catalysts that exhibit only specific types of sites required for desired product formation. Here we show that alkanethiolate self-assembled monolayers with varying surface densities can be used to tune selectivity to desired hydrogenation and hydrodeoxygenation products during the reaction of furfural on supported palladium catalysts. Vibrational spectroscopic studies demonstrate that the selectivity improvement is achieved by controlling the availability of specific sites for the hydrogenation of furfural on supported palladium catalysts through the selection of an appropriate alkanethiolate. Increasing self-assembled monolayer density by controlling the steric bulk of the organic tail ligand restricts adsorption on terrace sites and dramatically increases selectivity to desired products furfuryl alcohol and methylfuran. This technique of active-site selection simultaneously serves both to enhance selectivity and provide insight into the reaction mechanism.

  6. Chemical tailoring of teicoplanin with site-selective reactions.

    Science.gov (United States)

    Pathak, Tejas P; Miller, Scott J

    2013-06-05

    Semisynthesis of natural product derivatives combines the power of fermentation with orthogonal chemical reactions. Yet, chemical modification of complex structures represents an unmet challenge, as poor selectivity often undermines efficiency. The complex antibiotic teicoplanin eradicates bacterial infections. However, as resistance emerges, the demand for improved analogues grows. We have discovered chemical reactions that achieve site-selective alteration of teicoplanin. Utilizing peptide-based additives that alter reaction selectivities, certain bromo-teicoplanins are accessible. These new compounds are also scaffolds for selective cross-coupling reactions, enabling further molecular diversification. These studies enable two-step access to glycopeptide analogues not available through either biosynthesis or rapid total chemical synthesis alone. The new compounds exhibit a spectrum of activities, revealing that selective chemical alteration of teicoplanin may lead to analogues with attenuated or enhanced antibacterial properties, in particular against vancomycin- and teicoplanin-resistant strains.

  7. Method for Selection of Solvents for Promotion of Organic Reactions

    DEFF Research Database (Denmark)

    Gani, Rafiqul; Jiménez-González, Concepción; Constable, David J.C.

    2005-01-01

    is to produce, for a given reaction, a short list of chemicals that could be considered as potential solvents, to evaluate their performance in the reacting system, and, based on this, to rank them according to a scoring system. Several examples of application are given to illustrate the main features and steps......A method to select appropriate green solvents for the promotion of a class of organic reactions has been developed. The method combines knowledge from industrial practice and physical insights with computer-aided property estimation tools for selection/design of solvents. In particular, it employs...... estimates of thermodynamic properties to generate a knowledge base of reaction, solvent and environment related properties that directly or indirectly influence the rate and/or conversion of a given reaction. Solvents are selected using a rules-based procedure where the estimated reaction-solvent properties...

  8. Scope selection and control

    International Nuclear Information System (INIS)

    Guglielmi, F.

    2011-01-01

    OPG is preparing for a 4-unit refurbishment program at Darlington later in this decade. Key efforts underway include the selection of the right refurbishment scope that will allow Darlington to achieve top-decile performance post-refurbishment. For this to be possible, it is imperative that (1) plant/equipment condition be well understood, (2) post-refurbishment performance objectives be clearly defined, and (3) regulatory and other risks be carefully assessed and mitigated. Significant engineering, operations and maintenance support is required to complete this phase of the project cycle.

  9. Nonlinear control of the Salnikov model reaction

    DEFF Research Database (Denmark)

    Recke, Bodil; Jørgensen, Sten Bay

    1999-01-01

    This paper explores different nonlinear control schemes, applied to a simple model reaction. The model is the Salnikov model, consisting of two ordinary differential equations. The control strategies investigated are I/O-linearisation, Exact linearisation, exact linearisation combined with LQR...

  10. Conditional control in visual selection

    NARCIS (Netherlands)

    van Zoest, Wieske; Van der Stigchel, Stefan; Donk, Mieke

    2017-01-01

    Attention and eye movements provide a window into the selective processing of visual information. Evidence suggests that selection is influenced by various factors and is not always under the strategic control of the observer. The aims of this tutorial review are to give a brief introduction to eye

  11. Evaluating candidate reactions to selection practices using organisational justice theory.

    Science.gov (United States)

    Patterson, Fiona; Zibarras, Lara; Carr, Victoria; Irish, Bill; Gregory, Simon

    2011-03-01

    This study aimed to examine candidate reactions to selection practices in postgraduate medical training using organisational justice theory. We carried out three independent cross-sectional studies using samples from three consecutive annual recruitment rounds. Data were gathered from candidates applying for entry into UK general practice (GP) training during 2007, 2008 and 2009. Participants completed an evaluation questionnaire immediately after the short-listing stage and after the selection centre (interview) stage. Participants were doctors applying for GP training in the UK. Main outcome measures were participants' evaluations of the selection methods and perceptions of the overall fairness of each selection stage (short-listing and selection centre). A total of 23,855 evaluation questionnaires were completed (6893 in 2007, 10,497 in 2008 and 6465 in 2009). Absolute levels of perceptions of fairness of all the selection methods at both the short-listing and selection centre stages were consistently high over the 3years. Similarly, all selection methods were considered to be job-related by candidates. However, in general, candidates considered the selection centre stage to be significantly fairer than the short-listing stage. Of all the selection methods, the simulated patient consultation completed at the selection centre stage was rated as the most job-relevant. This is the first study to use a model of organisational justice theory to evaluate candidate reactions during selection into postgraduate specialty training. The high-fidelity selection methods are consistently viewed as more job-relevant and fairer by candidates. This has important implications for the design of recruitment systems for all specialties and, potentially, for medical school admissions. Using this approach, recruiters can systematically compare perceptions of the fairness and job relevance of various selection methods. © Blackwell Publishing Ltd 2011.

  12. Attachment and selective attention: disorganization and emotional Stroop reaction time.

    Science.gov (United States)

    Atkinson, Leslie; Leung, Eman; Goldberg, Susan; Benoit, Diane; Poulton, Lori; Myhal, Natalie; Blokland, Kirsten; Kerr, Sheila

    2009-01-01

    Although central to attachment theory, internal working models remain a useful heuristic in need of concretization. We compared the selective attention of organized and disorganized mothers using the emotional Stroop task. Both disorganized attachment and emotional Stroop response involve the coordination of strongly conflicting motivations under conditions of emotional arousal. Furthermore, much is known about the cognitive and neuromodulatory correlates of the Stroop that may inform attempts to substantiate the internal working model construct. We assessed 47 community mothers with the Adult Attachment Interview and the Working Model of the Child Interview in the third trimester of pregnancy. At 6 and 12 months postpartum, we assessed mothers with emotional Stroop tasks involving neutral, attachment, and emotion conditions. At 12 months, we observed their infants in the Strange Situation. Results showed that: disorganized attachment is related to relative Stroop reaction time, that is, unlike organized mothers, disorganized mothers respond to negative attachment/emotion stimuli more slowly than to neutral stimuli; relative speed of response is positively related to number of times the dyad was classified disorganized, and change in relative Stroop response time from 6 to 12 months is related to the match-mismatch status of mother and infant attachment classifications. We discuss implications in terms of automatic and controlled processing and, more specifically, cognitive threat tags, parallel distributed processing, and neuromodulation through norepinephrine and dopamine.

  13. Memory control with selective retention

    NARCIS (Netherlands)

    2012-01-01

    The present invention relates to a memory circuit and a method of controlling data retention in the memory circuit, wherein a supply signal is selectively switched to a respective one of at least two virtual supply lines (24) each shared by a respective one of a plurality of groups (30-1 to 30-n) of

  14. Memory control with selective retention

    NARCIS (Netherlands)

    2010-01-01

    The present invention relates to a memory circuit and a method of controlling data retention in the memory circuit, wherein a supply signal is selectively switched to a respective one of at least two virtual supply lines (24) each shared by a respective one of a plurality of groups (30-1 to 30-n) of

  15. Long life reaction control system design

    Science.gov (United States)

    Fanciullo, Thomas J.; Judd, Craig

    1993-02-01

    Future single stage to orbit systems will utilize oxygen/hydrogen propellants in their main propulsion means due to the propellant's high energy content and environmental acceptability. Operational effectiveness studies and life cycle cost studies have indicated that minimizing the number of different commodities on a given vehicle not only reduces cost, but reduces the ground span times in both the pre- and postflight operations. Therefore, oxygen and hydrogen should be used for the reaction controls systems, eliminating the need to deal with toxic or corrosive fluids. When the hydrogen scramjet powered NASP design development began in 1985, new system design studies considered overall integration of subsystems; in the context of that approach, O2/H2 reaction controls system were more than competitive with storable propellant systems and had the additional benefits of lower life cycle cost, rapid turnaround times, and O2 and H2 commodities for use throughout the vehicle. Similar benefits were derived in rocket-powered SSTO vehicles.

  16. Chlorine dioxide reaction with selected amino acids in water

    International Nuclear Information System (INIS)

    Navalon, Sergio; Alvaro, Mercedes; Garcia, Hermenegildo

    2009-01-01

    Chlorine dioxide is a hypochlorite alternative disinfectant agent. In this context, we have determined the products formed in the reaction of ClO 2 with selected amino acids as model compounds that can be present in natural waters. The reaction of tryptophane, histidine and tyrosine (10 ppm each) with ClO 2 were studied at molar ratios ranging from 0.25 to 4 in the presence or absence of oxygen. It was found that in the absence of oxygen adding substoichiometric amounts of ClO 2 creates products that are structurally similar to the starting amino acids. Through a series of cascade reactions the initial product distribution gradually evolves toward simple, small carbon chain products that are far from the starting amino acid. The reaction product distribution revealed that chlorine dioxide can attack the electron-rich aromatic moieties as well as the nitrogen atom lone electron pair. Our study is relevant to gain knowledge on the reaction mechanism of ClO 2 with ubiquitous amino acids present in natural waters.

  17. Reaction Control Engine for Space Launch Initiative

    Science.gov (United States)

    2002-01-01

    Engineers at the Marshall Space Flight Center (MSFC) have begun a series of engine tests on a new breed of space propulsion: a Reaction Control Engine developed for the Space Launch Initiative (SLI). The engine, developed by TRW Space and Electronics of Redondo Beach, California, is an auxiliary propulsion engine designed to maneuver vehicles in orbit. It is used for docking, reentry, attitude control, and fine-pointing while the vehicle is in orbit. The engine uses nontoxic chemicals as propellants, a feature that creates a safer environment for ground operators, lowers cost, and increases efficiency with less maintenance and quicker turnaround time between missions. Testing includes 30 hot-firings. This photograph shows the first engine test performed at MSFC that includes SLI technology. Another unique feature of the Reaction Control Engine is that it operates at dual thrust modes, combining two engine functions into one engine. The engine operates at both 25 and 1,000 pounds of force, reducing overall propulsion weight and allowing vehicles to easily maneuver in space. The low-level thrust of 25 pounds of force allows the vehicle to fine-point maneuver and dock while the high-level thrust of 1,000 pounds of force is used for reentry, orbit transfer, and coarse positioning. SLI is a NASA-wide research and development program, managed by the MSFC, designed to improve safety, reliability, and cost effectiveness of space travel for second generation reusable launch vehicles.

  18. Deciphering Selectivity in Organic Reactions: A Multifaceted Problem.

    Science.gov (United States)

    Balcells, David; Clot, Eric; Eisenstein, Odile; Nova, Ainara; Perrin, Lionel

    2016-05-17

    Computational chemistry has made a sustained contribution to the understanding of chemical reactions. In earlier times, half a century ago, the goal was to distinguish allowed from forbidden reactions (e.g., Woodward-Hoffmann rules), that is, reactions with low or high to very high activation barriers. A great achievement of computational chemistry was also to contribute to the determination of structures with the bonus of proposing a rationalization (e.g., anomeric effect, isolobal analogy, Gillespie valence shell pair electron repulsion rules and counter examples, Wade-Mingos rules for molecular clusters). With the development of new methods and the constant increase in computing power, computational chemists move to more challenging problems, close to the daily concerns of the experimental chemists, in determining the factors that make a reaction both efficient and selective: a key issue in organic synthesis. For this purpose, experimental chemists use advanced synthetic and analytical techniques to which computational chemists added other ways of determining reaction pathways. The transition states and intermediates contributing to the transformation of reactants into the desired and undesired products can now be determined, including their geometries, energies, charges, spin densities, spectroscopy properties, etc. Such studies remain challenging due to the large number of chemical species commonly present in the reactive media whose role may have to be determined. Calculating chemical systems as they are in the experiment is not always possible, bringing its own share of complexity through the large number of atoms and the associated large number of conformers to consider. Modeling the chemical species with smaller systems is an alternative that historically led to artifacts. Another important topic is the choice of the computational method. While DFT is widely used, the vast diversity of functionals available is both an opportunity and a challenge. Though

  19. Selective free radical reactions using supercritical carbon dioxide.

    Science.gov (United States)

    Cormier, Philip J; Clarke, Ryan M; McFadden, Ryan M L; Ghandi, Khashayar

    2014-02-12

    We report herein a means to modify the reactivity of alkenes, and particularly to modify their selectivity toward reactions with nonpolar reactants (e.g., nonpolar free radicals) in supercritical carbon dioxide near the critical point. Rate constants for free radical addition of the light hydrogen isotope muonium to ethylene, vinylidene fluoride, and vinylidene chloride in supercritical carbon dioxide are compared over a range of pressures and temperatures. Near carbon dioxide's critical point, the addition to ethylene exhibits critical speeding up, while the halogenated analogues display critical slowing. This suggests that supercritical carbon dioxide as a solvent may be used to tune alkene chemistry in near-critical conditions.

  20. Copper-catalysed selective hydroamination reactions of alkynes

    Science.gov (United States)

    Shi, Shi-Liang; Buchwald, Stephen L.

    2015-01-01

    The development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a long-standing goal of chemical research. Despite the centrality of amines in a number of important research areas, including medicinal chemistry, total synthesis and materials science, a general, selective and step-efficient synthesis of amines is still needed. Here, we describe a set of mild catalytic conditions utilizing a single copper-based catalyst that enables the direct preparation of three distinct and important amine classes (enamines, α-chiral branched alkylamines and linear alkylamines) from readily available alkyne starting materials with high levels of chemo-, regio- and stereoselectivity. This methodology was applied to the asymmetric synthesis of rivastigmine and the formal synthesis of several other pharmaceutical agents, including duloxetine, atomoxetine, fluoxetine and tolterodine.

  1. Copper-catalyzed selective hydroamination reactions of alkynes

    Science.gov (United States)

    Shi, Shi-Liang; Buchwald, Stephen L.

    2014-01-01

    The development of selective reactions that utilize easily available and abundant precursors for the efficient synthesis of amines is a longstanding goal of chemical research. Despite the centrality of amines in a number of important research areas, including medicinal chemistry, total synthesis and materials science, a general, selective, and step-efficient synthesis of amines is still needed. In this work we describe a set of mild catalytic conditions utilizing a single copper-based catalyst that enables the direct preparation of three distinct and important amine classes (enamines, α-chiral branched alkylamines, and linear alkylamines) from readily available alkyne starting materials with high levels of chemo-, regio-, and stereoselectivity. This methodology was applied to the asymmetric synthesis of rivastigmine and the formal synthesis of several other pharmaceutical agents, including duloxetine, atomoxetine, fluoxetine, and tolterodine. PMID:25515888

  2. Spin-selective recombination reactions of radical pairs: Experimental test of validity of reaction operators

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Kiminori [Department of Chemistry, University of Oxford, Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory, Oxford (United Kingdom); Liddell, Paul; Gust, Devens [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona, 85287-1604 (United States); Hore, P. J. [Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, Oxford (United Kingdom)

    2013-12-21

    Spin-selective reactions of radical pairs are conventionally modelled using an approach that dates back to the 1970s [R. Haberkorn, Mol. Phys. 32, 1491 (1976)]. An alternative approach based on the theory of quantum measurements has recently been suggested [J. A. Jones and P. J. Hore, Chem. Phys. Lett. 488, 90 (2010)]. We present here the first experimental attempt to discriminate between the two models. Pulsed electron paramagnetic resonance spectroscopy has been used to investigate intramolecular electron transfer in the radical pair form of a carotenoid-porphyrin-fullerene molecular triad. The rate of spin-spin relaxation of the fullerene radical in the triad was found to be inconsistent with the quantum measurement description of the spin-selective kinetics, and in accord with the conventional model when combined with spin-dephasing caused by rotational modulation of the anisotropic g-tensor of the fullerene radical.

  3. Control Configuration Selection for Multivariable Descriptor Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Stoustrup, Jakob

    2012-01-01

    Control configuration selection is the procedure of choosing the appropriate input and output pairs for the design of SISO (or block) controllers. This step is an important prerequisite for a successful industrial control strategy. In industrial practices it is often the case that the system, whi...... is that it can be used to propose a richer sparse or block diagonal controller structure. The interaction measure is used for control configuration selection of the linearized CSTR model with descriptor from....

  4. Medium-Ring Effects on the Endo/Exo Selectivity of the Organocatalytic Intramolecular Diels-Alder Reaction.

    Science.gov (United States)

    Hooper, Joel F; James, Natalie C; Bozkurt, Esra; Aviyente, Viktorya; White, Jonathan M; Holland, Mareike C; Gilmour, Ryan; Holmes, Andrew B; Houk, K N

    2015-12-18

    The intramolecular Diels-Alder reaction has been used as a powerful method to access the tricyclic core of the eunicellin natural products from a number of 9-membered-ring precursors. The endo/exo selectivity of this reaction can be controlled through a remarkable organocatalytic approach, employing MacMillan's imidazolidinone catalysts, although the mechanistic origin of this selectivity remains unclear. We present a combined experimental and density functional theory investigation, providing insight into the effects of medium-ring constraints on the organocatalyzed intramolecular Diels-Alder reaction to form the isobenzofuran core of the eunicellins.

  5. Polyol synthesis of silver nanocubes via moderate control of the reaction atmosphere.

    Science.gov (United States)

    Jeon, Seog-Jin; Lee, Jae-Hwang; Thomas, Edwin L

    2014-12-01

    Silver nanocubes were successfully synthesized at high yield in variously controlled reaction atmospheres by balancing etching of O2/Cl(-) and reduction of glycolaldehyde. There have been efforts to control the O2 content in reaction atmospheres by purging of O2 or Ar gas for the balancing, but we found that moderate control of reaction atmosphere, just by careful timing of the opening and the capping of the reaction vial, greatly enhanced reproducibility. Enhanced reproducibility is attributed to alleviation of evaporation and condensation of glycolaldehyde (b.p.=131°C) by using capping at reaction temperatures higher than the b.p. of glycolaldehyde rather than purging with gas. The most important finding is that seeding is initiated by HNO3 induced deoxygenation reaction in the gas phase. O2 is consumed by oxidation of NO generated from the silver etching reaction by HNO3, which effectively controls the reaction atmosphere without introduction of gas. Our simple method to control reaction atmosphere reduces the overall reaction time to one fifth of the previous result and provides excellent size and distribution selectivity of the Ag nanocube product. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Communication: Control of chemical reactions using electric field gradients

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, Shivaraj D.; Tsori, Yoav, E-mail: tsori@bgu.ac.il [Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2016-05-21

    We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.

  7. Communication: Control of chemical reactions using electric field gradients.

    Science.gov (United States)

    Deshmukh, Shivaraj D; Tsori, Yoav

    2016-05-21

    We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.

  8. State selective reactions of cosmic dust analogues at cryogenic temperatures

    International Nuclear Information System (INIS)

    Perry, James Samuel Anthony

    2001-01-01

    Molecular hydrogen (H 2 ) is the most abundant molecule in interstellar space. It is crucial for initiating all of the chemistry in the Interstellar Medium (ISM) and consequently plays an important role in star formation. However, the amount of H 2 believed to exist in the ISM cannot be accounted for by formation through gas-phase reactions alone. The current, widely accepted theory, is that H 2 forms on the surface of cosmic dust grains. These grains are thought to be composed of amorphous forms of carbon or silicates with temperatures of around 10 K. This thesis describes a new experiment that has been constructed to study H 2 formation on the surface of cosmic dust analogues and presents the initial experimental results. The experiment simulates, through ultra-high vacuum and the use of cryogenics, the conditions of the ISM where cosmic dust grains and H 2 molecules exist. During the experiment, a beam of atomic hydrogen is aimed at a cosmic dust analogue target. H 2 formed on the target's surface is ionised using a laser spectroscopy technique known as Resonance Enhanced Multiphoton lonisation (REMPI) and detected using time-of-flight mass spectrometry. The sensitivity of REMPI is such that H 2 molecules can be ionised in selective internal energy states. This allows the rovibrational populations of the H 2 molecules desorbing from the cosmic dust targets to be determined, providing information on the energy budget of the H 2 formation process in the ISM. Preliminary results from the experiment show that H 2 molecules formed on a diamond-like-carbon surface have a significant non-thermal population of excited vibrational and rotational energy states. (author)

  9. Study on the Attitude Control of Spacecraft Using Reaction Wheels

    Directory of Open Access Journals (Sweden)

    Ju-Young Du

    1998-06-01

    Full Text Available Attitude determination and control of satellite is important component which determines the accomplish satellite missions. In this study, attitude control using reaction wheels and momentum dumping of wheels are considered. Attitude control law is designed by Sliding control and LQR. Attitude maneuver control law is obtained by Shooting method. Wheels momentum dumping control law is designed by Bang-Bang control. Four reaction wheels are configurated for minimized the electric power consumption. Wheels control torque and magnetic moment of magnetic torquer are limited.

  10. Towards Automatic Decentralized Control Structure Selection

    DEFF Research Database (Denmark)

    Jørgensen, John Bagterp; Jørgensen, Sten Bay

    2000-01-01

    for decentralized control is determined automatically, and the resulting decentralized control structure is automatically tuned using standard techniques. Dynamic simulation of the resulting process system gives immediate feedback to the process design engineer regarding practical operability of the process......A subtask in integration of design and control of chemical processes is the selection of a control structure. Automating the selection of the control structure enables sequential integration of process and control design. As soon as the process is specified or computed, a structure....... The control structure selection problem is formulated as a special MILP employing cost coefficients which are computed using Parseval's theorem combined with RGA and IMC concepts. This approach enables selection and tuning of large-scale plant-wide decentralized controllers through efficient combination...

  11. Control of Maillard Reactions in Foods: Strategies and Chemical Mechanisms.

    Science.gov (United States)

    Lund, Marianne N; Ray, Colin A

    2017-06-14

    Maillard reactions lead to changes in food color, organoleptic properties, protein functionality, and protein digestibility. Numerous different strategies for controlling Maillard reactions in foods have been attempted during the past decades. In this paper, recent advances in strategies for controlling the Maillard reaction and subsequent downstream reaction products in food systems are critically reviewed. The underlying mechanisms at play are presented, strengths and weaknesses of each strategy are discussed, and reasonable reaction mechanisms are proposed to reinforce the evaluations. The review includes strategies involving addition of functional ingredients, such as plant polyphenols and vitamins, as well as enzymes. The resulting trapping or modification of Maillard targets, reactive intermediates, and advanced glycation endproducts (AGEs) are presented with their potential unwanted side effects. Finally, recent advances in processing for control of Maillard reactions are discussed.

  12. Reaction selectivity studies on nanolithographically-fabricated platinum model catalyst arrays

    Energy Technology Data Exchange (ETDEWEB)

    Grunes, Jeffrey Benjamin [Univ. of California, Berkeley, CA (United States)

    2004-05-01

    In an effort to understand the molecular ingredients of catalytic activity and selectivity toward the end of tuning a catalyst for 100% selectivity, advanced nanolithography techniques were developed and utilized to fabricate well-ordered two-dimensional model catalyst arrays of metal nanostructures on an oxide support for the investigation of reaction selectivity. In-situ and ex-situ surface science techniques were coupled with catalytic reaction data to characterize the molecular structure of the catalyst systems and gain insight into hydrocarbon conversion in heterogeneous catalysis. Through systematic variation of catalyst parameters (size, spacing, structure, and oxide support) and catalytic reaction conditions (hydrocarbon chain length, temperature, pressures, and gas composition), the data presented in this dissertation demonstrate the ability to direct a reaction by rationally adjusting, through precise control, the design of the catalyst system. Electron beam lithography (EBL) was employed to create platinum nanoparticles on an alumina (Al2O3) support. The Pt nanoparticle spacing (100-150-nm interparticle distance) was varied in these samples, and they were characterized using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), both before and after reactions. The TEM studies showed the 28-nm Pt nanoparticles with 100 and 150-nm interparticle spacing on alumina to be polycrystalline in nature, with crystalline sizes of 3-5 nm. The nanoparticle crystallites increased significantly after heat treatment. The nanoparticles were still mostly polycrystalline in nature, with 2-3 domains. The 28-nm Pt nanoparticles deposited on alumina were removed by the AFM tip in contact mode with a normal force of approximately 30 nN. After heat treatment at 500 C in vacuum for 3 hours, the AFM tip, even at 4000 nN, could not remove the platinum

  13. Towards Automatic Decentralized Control Structure Selection

    DEFF Research Database (Denmark)

    for decentralized control is determined automatically, and the resulting decentralized control structure is automatically tuned using standard techniques. Dynamic simulation of the resulting process system gives immediate feedback to the process design engineer regarding practical operability of the process......A subtask in integration of design and control of chemical processes is the selection of a control structure. Automating the selection of the control structure enables sequential integration of process and controld esign. As soon as the process is specified or computed, a structure....... The control structure selection problem is formulated as a special MILP employing cost coefficients which are computed using Parseval's theorem combined with RGA and IMC concepts. This approach enables selection and tuning of large-scale plant-wide decentralized controllers through efficient combination...

  14. A cellular automata approach to chemical reactions : 1 reaction controlled systems

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.

    2013-01-01

    A direct link between the chemical reaction controlled (shrinking core) model and cellular automata, to study the dissolution of particles, is derived in this paper. Previous research on first and second order reactions is based on the concentration of the reactant. The present paper describes the

  15. Outpatient desensitization in selected patients with platinum hypersensitivity reactions.

    Science.gov (United States)

    O'Malley, David M; Vetter, Monica Hagan; Cohn, David E; Khan, Ambar; Hays, John L

    2017-06-01

    Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Selection of Air Traffic Controllers,

    Science.gov (United States)

    1984-08-01

    Institute of Bahavioral Research, Texas Christian University Joseph A. Tucker, Ph.D. Professor of Instructional Technology, The Catholic University of...Peace Corps volunteers (Gordon, 1967); nursing students in their first year of training (Katzell, 1968); nursing turn- over in a teaching hospital (Saleh...retired FAA controllers and instructors who volunteered to help in the crisis. A student’s first few days (Phase I) at the Academy are spent in per

  17. Directing Reaction Pathways through Controlled Reactant Binding at Pd-TiO2 Interfaces.

    Science.gov (United States)

    Zhang, Jing; Wang, Bingwen; Nikolla, Eranda; Medlin, J Will

    2017-06-01

    Recent efforts to design selective catalysts for multi-step reactions, such as hydrodeoxygenation (HDO), have emphasized the preparation of active sites at the interface between two materials having different properties. However, achieving precise control over interfacial properties, and thus reaction selectivity, has remained a challenge. Here, we encapsulated Pd nanoparticles (NPs) with TiO 2 films of regulated porosity to gain a new level of control over catalyst performance, resulting in essentially 100 % HDO selectivity for two biomass-derived alcohols. This catalyst also showed exceptional reaction specificity in HDO of furfural and m-cresol. In addition to improving HDO activity by maximizing the interfacial contact between the metal and metal oxide sites, encapsulation by the nanoporous oxide film provided a significant selectivity boost by restricting the accessible conformations of aromatics on the surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Controlled thermonuclear reactions and Tora Supra program

    International Nuclear Information System (INIS)

    1988-01-01

    The research programs for the nuclear energy production by means of thermonuclear fusion are shown. TORA SUPRA, Joint European Torus, Next European Torus and those developed at the Atomic Energy Center are described. The controlled fusion necessary conditions, the energy and confinement balance, and the research of a better tokamak configuration are discussed. A description of TORA SUPRA, the ways of achieving the project and the expected delays are shown. The Controlled Fusion Research Department functions, concerning these programs, are described. The importance of international cooperation and the perspectives about the use of controlled fusion are underlined [fr

  19. Design and Stability of an On-Orbit Attitude Control System Using Reaction Control Thrusters

    Science.gov (United States)

    Hall, Robert A.; Hough, Steven; Orphee, Carolina; Clements, Keith

    2016-01-01

    Basic principles for the design and stability of a spacecraft on-orbit attitude control system employing on-off Reaction Control System (RCS) thrusters are presented. Both vehicle dynamics and the control system actuators are inherently nonlinear, hence traditional linear control system design approaches are not directly applicable. This paper has two main aspects: It summarizes key RCS design principles from earlier NASA vehicles, notably the Space Shuttle and Space Station programs, and introduces advances in the linear modelling and analyses of a phase plane control system derived in the initial development of the NASA's next upper stage vehicle, the Exploration Upper Stage (EUS). Topics include thruster hardware specifications, phase plane design and stability, jet selection approaches, filter design metrics, and RCS rotational maneuver logic.

  20. Vibrational-state-selected ion--molecule reaction cross sections at thermal energies

    NARCIS (Netherlands)

    Pijkeren, D. van; Boltjes, E.; Eck, J. van; Niehaus, A.

    1984-01-01

    A method designed to measure relative ion—molecule reaction rates at thermal collision energies for selected reactant ion vibrational states is described. Relative reaction rates are determined for the three endothermic reactions: H2+ (υ)(He,H)HeH+, H2+ (υ)(Ne,H)NeH+, D2+(υ)(Ne, D)NeD+, and for the

  1. Criteria of reaction identification and selection of badly measured events

    International Nuclear Information System (INIS)

    Linetskij, A.R.; Lyubarskij, G.Ya.; Sagalovich, N.E.

    1979-01-01

    Basing on photoemulsion methods of studying channels of multiparticle nuclear reactions the metrological characteristics of a physical technique are described in the process of its development. To increase the accuracy of reaction identification the technique for picture measuring has been complicated by introducing calibration measurements of tracks of stopped in the emulsion primary α-particles. Callibration measurements have support assumptions on energy oscillations of the primary beam and made possible the employment of actual values of this energy instead of rated one during mathematical processing. By using simulation reactions the effect of errors in determining the contraction ratio has been estimated. It has been found that rather a small error in determining the contraction (+-20%) results in additional casting-out 8-15% of measured events

  2. Attosecond-recollision-controlled selective fragmentation of polyatomic molecules.

    Science.gov (United States)

    Xie, Xinhua; Doblhoff-Dier, Katharina; Roither, Stefan; Schöffler, Markus S; Kartashov, Daniil; Xu, Huailiang; Rathje, Tim; Paulus, Gerhard G; Baltuška, Andrius; Gräfe, Stefanie; Kitzler, Markus

    2012-12-14

    Control over various fragmentation reactions of a series of polyatomic molecules (acetylene, ethylene, 1,3-butadiene) by the optical waveform of intense few-cycle laser pulses is demonstrated experimentally. We show both experimentally and theoretically that the responsible mechanism is inelastic ionization from inner-valence molecular orbitals by recolliding electron wave packets, whose recollision energy in few-cycle ionizing laser pulses strongly depends on the optical waveform. Our work demonstrates an efficient and selective way of predetermining fragmentation and isomerization reactions in polyatomic molecules on subfemtosecond time scales.

  3. Modeling of Reaction Processes Controlled by Diffusion

    International Nuclear Information System (INIS)

    Revelli, Jorge

    2003-01-01

    Stochastic modeling is quite powerful in science and technology.The technics derived from this process have been used with great success in laser theory, biological systems and chemical reactions.Besides, they provide a theoretical framework for the analysis of experimental results on the field of particle's diffusion in ordered and disordered materials.In this work we analyze transport processes in one-dimensional fluctuating media, which are media that change their state in time.This fact induces changes in the movements of the particles giving rise to different phenomena and dynamics that will be described and analyzed in this work.We present some random walk models to describe these fluctuating media.These models include state transitions governed by different dynamical processes.We also analyze the trapping problem in a lattice by means of a simple model which predicts a resonance-like phenomenon.Also we study effective diffusion processes over surfaces due to random walks in the bulk.We consider different boundary conditions and transitions movements.We derive expressions that describe diffusion behaviors constrained to bulk restrictions and the dynamic of the particles.Finally it is important to mention that the theoretical results obtained from the models proposed in this work are compared with Monte Carlo simulations.We find, in general, excellent agreements between the theory and the simulations

  4. Reactivity and selectivity of arenes in reactions with ozone

    International Nuclear Information System (INIS)

    Vysotskii, Yu.B.; Mestechkin, M.M.; Sivyakova, L.N.; Tyupalo, N.F.

    1987-01-01

    The reactions of arenes with ozone, distinguished by the variety of products (quinones, aldehydes, acids), are of interest not only from the theoretical standpoint but also are of preparative value in the case of polycyclic hydrocarbons. In this work a quantitative treatment of this reaction is given on the basis of direct kinetic measurements and simple quantum chemical means, permitting its rate constants and the yield of the products to be related to the elements of electronic structure readily subject to quantum mechanical calculation

  5. Unconventional exo selectivity in thermal normal-electron-demand Diels-Alder reactions

    Science.gov (United States)

    Ho, Guo-Ming; Huang, Ci-Jhang; Li, Elise Yu-Tzu; Hsu, Sheng-Kai; Wu, Ti; Zulueta, Medel Manuel L.; Wu, Kevin Binchia; Hung, Shang-Cheng

    2016-10-01

    The Diels-Alder reaction is a useful tool for generating functionalized chiral molecules through the concerted cycloaddition of dienes and dienophiles leading to six-membered rings. Traditionally, the selective predictions of the products rely heavily on consideration of the secondary orbital interactions that stabilize the endo pathway. However, there remain some basic examples defying this notion and produce the exo-isomer as major product. Here we systematically evaluated of the structural features driving exo selectivity in thermal normal-electron-demand Diels-Alder reactions. Substitution at the Cβ position and the size and electronegativity of the electron-withdrawing group of the dienophile are contributing factors. Experimental and computational studies both point toward the steric and electrostatic forces between the substituents in both the diene and the dienophile that increase the likelihood of the exo pathway. For these substrates, the dominance of the endo pathway is reduced by transition state distortions and poor structural alignments of the reacting partners. We also noted the tilt of the dienophile with respect to the diene causing steric strain on the functionalities at the more advanced bond forming carbon-carbon position of the endo transition state. Insights into such factors may benefit synthetic planning and asserting control over this important named reaction.

  6. Acoustic Resonance Reaction Control Thruster (ARCTIC), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — ORBITEC proposes to develop and demonstrate the innovative Acoustic Resonance Reaction Control Thruster (ARCTIC) to provide rapid and reliable in-space impulse...

  7. Mars Ascent Vehicle Reaction Control System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — During this Phase I NASA program, Valley Tech Systems (VTS) will develop an innovative solid Reaction Control System (RCS) architecture concept design that can...

  8. Modeling Reaction Control System Effects on Mars Odyssey

    National Research Council Canada - National Science Library

    Hanna, Jill

    2002-01-01

    ...) simulations to determine rotational motion of the spacecraft. The main objective of this study was to assess the reaction control system models and their effects on the atmospheric flight of Odyssey...

  9. Controlled trifluoromethylation reactions of alkynes through visible-light photoredox catalysis.

    Science.gov (United States)

    Iqbal, Naeem; Jung, Jaehun; Park, Sehyun; Cho, Eun Jin

    2014-01-07

    The control of a reaction that can form multiple products is a highly attractive and challenging concept in synthetic chemistry. A set of valuable CF3 -containing molecules, namely trifluoromethylated alkenyl iodides, alkenes, and alkynes, were selectively generated from alkynes and CF3 I by environmentally benign and efficient visible-light photoredox catalysis. Subtle differences in the combination of catalyst, base, and solvent enabled the control of reactivity and selectivity for the reaction between an alkyne and CF3 I. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Solitary wave solutions of selective nonlinear diffusion-reaction ...

    Indian Academy of Sciences (India)

    An auto-Bäcklund transformation derived in the homogeneous balance method is employed to obtain several new exact solutions of certain kinds of nonlin- ear diffusion-reaction (D-R) equations. These equations arise in a variety of problems in physical, chemical, biological, social and ecological sciences. Keywords.

  11. Nanoscale control of reversible chemical reaction between fullerene C60 molecules using scanning tunneling microscope.

    Science.gov (United States)

    Nakaya, Masato; Kuwahara, Yuji; Aono, Masakazu; Nakayama, Tomonobu

    2011-04-01

    The nanoscale control of reversible chemical reactions, the polymerization and depolymerization between C60 molecules, has been investigated. Using a scanning tunneling microscope (STM), the polymerization and depolymerization can be controlled at designated positions in ultrathin films of C60 molecules. One of the two chemical reactions can be selectively induced by controlling the sample bias voltage (V(s)); the application of negative and positive values of V(s) results in polymerization and depolymerization, respectively. The selectivity between the two chemical reactions becomes extremely high when the thickness of the C60 film increases to more than three molecular layers. We conclude that STM-induced negative and positive electrostatic ionization are responsible for the control of the polymerization and depolymerization, respectively.

  12. Quality Control Of Selected Pesticides With GC

    Energy Technology Data Exchange (ETDEWEB)

    Karasali, H. [Benaki Phytopathological Institute Laboratory of Physical and Chemical Analysis of Pesticides, Ekalis (Greece)

    2009-07-15

    The practical quality control of selected pesticides with GC is treated. Detailed descriptions are given on materials and methods used, including sample preparation and GC operating conditions. The systematic validation of multi methods is described, comprising performance characteristics in routine analysis, like selectivity, specificity etc. This is illustrated by chromatograms, calibration curves and tables derived from real laboratory data. (author)

  13. reaction of selected common bean genotypes to physiological races

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    Department of Biological Sciences, Egerton University, P. O. Box 536, Egerton, Kenya. 1Department of Plant ... order to identify potential sources of resistance to angular leaf spot. Selected bean ...... phaseolicola (Burk, 1926) Young, Dye and.

  14. NASA Ares I Launch Vehicle Roll and Reaction Control Systems Design Status

    Science.gov (United States)

    Butt, Adam; Popp, Chris G.; Pitts, Hank M.; Sharp, David J.

    2009-01-01

    This paper provides an update of design status following the preliminary design review of NASA s Ares I first stage roll and upper stage reaction control systems. The Ares I launch vehicle has been chosen to return humans to the moon, mars, and beyond. It consists of a first stage five segment solid rocket booster and an upper stage liquid bi-propellant J-2X engine. Similar to many launch vehicles, the Ares I has reaction control systems used to provide the vehicle with three degrees of freedom stabilization during the mission. During launch, the first stage roll control system will provide the Ares I with the ability to counteract induced roll torque. After first stage booster separation, the upper stage reaction control system will provide the upper stage element with three degrees of freedom control as needed. Trade studies and design assessments conducted on the roll and reaction control systems include: propellant selection, thruster arrangement, pressurization system configuration, and system component trades. Since successful completion of the preliminary design review, work has progressed towards the critical design review with accomplishments made in the following areas: pressurant / propellant tank, thruster assembly, and other component configurations, as well as thruster module design, and waterhammer mitigation approach. Also, results from early development testing are discussed along with plans for upcoming system testing. This paper concludes by summarizing the process of down selecting to the current baseline configuration for the Ares I roll and reaction control systems.

  15. Site selectivity of specific reaction steps important for catalysis

    DEFF Research Database (Denmark)

    Nielsen, Kenneth

    ) overlayer system. In the STM study of the structure sensitivity of the CO dissociation reaction on the Ru(0 1 54) sample, it was determined that after cooling the sample from 700K to 400K in 10-8Torr of CO or in the CO that was left after a TPD, the sample displayed periodic decorations on every other...... site, is the most stable conguration after dissociation. Preliminary results where the sample was exposed to high doses of CO, at a CO pressure of 10-5 Torr and a temperature of 550K (dissociation conditions) indicated that especially every other step had a very rough appearance after 7 min exposure...

  16. The reaction of selected metal powders with Arklone

    International Nuclear Information System (INIS)

    Benson, C.G.; Hawes, P.M.

    1985-10-01

    Experimental work has been carried out to investigate possible reactions between Arklone 1,1,2-trichloro-1,2,2-trifluroethane and magnesium, beryllium and aluminium powders. Differential Thermal Analysis was used to study small scale samples in the temperature range from -35 to 200 0 C. Larger scale studies were also carried out using pure Arklone and Arklone with water or acids (HCL or HF) as contaminants. Results are reported for metal powders of various particle sizes. The systems studied were all found to be unreactive in conditions which are expected to be encountered in a Decontamination and Disposal Facility. (author)

  17. Molecular controls of the oxygenation and redox reactions of hemoglobin.

    Science.gov (United States)

    Bonaventura, Celia; Henkens, Robert; Alayash, Abdu I; Banerjee, Sambuddha; Crumbliss, Alvin L

    2013-06-10

    The broad classes of O(2)-binding proteins known as hemoglobins (Hbs) carry out oxygenation and redox functions that allow organisms with significantly different physiological demands to exist in a wide range of environments. This is aided by allosteric controls that modulate the protein's redox reactions as well as its O(2)-binding functions. The controls of Hb's redox reactions can differ appreciably from the molecular controls for Hb oxygenation and come into play in elegant mechanisms for dealing with nitrosative stress, in the malarial resistance conferred by sickle cell Hb, and in the as-yet unsuccessful designs for safe and effective blood substitutes. An important basic principle in consideration of Hb's redox reactions is the distinction between kinetic and thermodynamic reaction control. Clarification of these modes of control is critical to gaining an increased understanding of Hb-mediated oxidative processes and oxidative toxicity in vivo. This review addresses emerging concepts and some unresolved questions regarding the interplay between the oxygenation and oxidation reactions of structurally diverse Hbs, both within red blood cells and under acellular conditions. Developing methods that control Hb-mediated oxidative toxicity will be critical to the future development of Hb-based blood substitutes.

  18. Molecular Controls of the Oxygenation and Redox Reactions of Hemoglobin

    Science.gov (United States)

    Henkens, Robert; Alayash, Abdu I.; Banerjee, Sambuddha; Crumbliss, Alvin L.

    2013-01-01

    Abstract Significance: The broad classes of O2-binding proteins known as hemoglobins (Hbs) carry out oxygenation and redox functions that allow organisms with significantly different physiological demands to exist in a wide range of environments. This is aided by allosteric controls that modulate the protein's redox reactions as well as its O2-binding functions. Recent Advances: The controls of Hb's redox reactions can differ appreciably from the molecular controls for Hb oxygenation and come into play in elegant mechanisms for dealing with nitrosative stress, in the malarial resistance conferred by sickle cell Hb, and in the as-yet unsuccessful designs for safe and effective blood substitutes. Critical Issues: An important basic principle in consideration of Hb's redox reactions is the distinction between kinetic and thermodynamic reaction control. Clarification of these modes of control is critical to gaining an increased understanding of Hb-mediated oxidative processes and oxidative toxicity in vivo. Future Directions: This review addresses emerging concepts and some unresolved questions regarding the interplay between the oxygenation and oxidation reactions of structurally diverse Hbs, both within red blood cells and under acellular conditions. Developing methods that control Hb-mediated oxidative toxicity will be critical to the future development of Hb-based blood substitutes. Antioxid. Redox Signal. 18, 2298–2313. PMID:23198874

  19. Selected ion flow tube studies of S2+ reactions with a series of organic molecules

    Science.gov (United States)

    Decker, Brian K.; Adams, Nigel G.

    1997-11-01

    A selected ion flow tube (SIFT) has been used to study the reactions of S2+ with a series of organic molecules (as well as H2, CO, NH3, NO and NO2). These include the hydrocarbons, C2H4, C2H6, CH2CCH2, CH3CHCH2 and C3H8; alcohols and thiols, CH3OH, C2H5OH, CH3SH and C2H5SH; ethers (CH3)2O and (C2H5)2O; aldehydes and ketones, CH3CHO, C2H5CHO and (CH3)2CO; and carboxylic acids and esters, HCO2H, HCO2CH3, HCO2C2H5, CH3CO2H, CH3CO2CH3, CH3CO2C2H5, C2H5CO2H, C2H5CO2CH3 and C2H5CO2C2H5. The rate coefficients are generally close to the collisional values, with exceptions among the reactions involving the smaller molecules. Most prevalent are abstraction reactions leading to formation of the thiosulfeno radical, HS2, or its protonated form; three-body associations; and channels leading to formation of the acetyl and propionyl cations, CH3CO+ and C2H5CO+, respectively. Only in reactions involving the alkenes is cleavage of the S---S bond of S2+ observed. The isomeric molecules in the data set generally react very differently, as would be expected from reactivity controlled by the position and complexity of the functional groups. The data are discussed in terms of reaction mechanisms, thermodynamics, and implications for interstellar chemistry.

  20. Determining two-step control in heterogeneous catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, T; Silveston, P L; Hudgins, R R

    1979-10-01

    The data by Thaller and Thodos on the sec.-butanol dehydrogenation to methyl ethyl ketone on brass catalyst indicated that a dual site surface reaction was rate-controlling below 575/sup 0/K and hydrogen desorption was rate-controlling above 616/sup 0/K (Vertical BarAIChE J.

  1. Control rod selecting and driving device

    International Nuclear Information System (INIS)

    Isobe, Hideo.

    1981-01-01

    Purpose: To simultaneously drive a predetermined number of control rods in a predetermined mode by the control of addresses for predetermined number of control rods and read or write of driving codified data to and from the memory by way of a memory controller. Constitution: The system comprises a control rod information selection device for selecting predetermined control rods from a plurality of control rods disposed in a reactor and outputting information for driving them in a predetermined mode, a control rod information output device for codifying the information outputted from the above device and outputting the addresses to the predetermined control rods and driving mode coded data, and a driving device for driving said predetermined control rods in a predetermined mode in accordance with the codified data outputted from the above device, said control rod infromation output device comprising a memory device capable of storing a predetermined number of the codified data and a memory control device for storing the predetermined number of data into the above memory device at a predetermined timing while successively outputting the thus stored predetermined number of data at a predetermined timing. (Seki, T.)

  2. Enrichment: CRISLA [chemical reaction by isotope selective activation] aims to reduce costs

    International Nuclear Information System (INIS)

    Eerkens, J.W.

    1989-01-01

    Every year, more than $3 billion is spent on enriching uranium. CRISLA (Chemical Reaction by Isotope Selective Activation) uses a laser-catalyzed chemical reaction which, its proponents claim, could substantially reduce these costs. In CRISLA, an infrared CO laser illuminates the intracavity reaction cell (IC) at a frequency tuned to excite primarily UF 6 . When UF 6 and co-reactant RX are passed through the IC, the tuned laser photons preferentially enhance the reaction of UF 6 with RX ten-thousand-fold over the thermal reaction rate. Thus the laser serves as an activator and the chemical energy for separation is largely chemical. (author)

  3. Synthesis of porous gold nanoshells by controlled transmetallation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Pattabi, Manjunatha, E-mail: manjupattabi@yahoo.com; M, Krishnaprabha [Department of Materials Science, Mangalore University, Mangalagangothri-574199 (India)

    2015-06-24

    Aqueous synthesis of porous gold nanoshells in one step is carried out through controlled transmetallation (TM) reaction using a naturally available egg shell membrane (ESM) as a barrier between the sacrificial silver particles (AgNPs) and the gold precursor solution (HAuCl{sub 4}). The formation of porous gold nanoshells via TM reaction is inferred from UV-Vis spectroscopy and the scanning electron microscopic (SEM) studies.

  4. Method and apparatus for controlling gas evolution from chemical reactions

    Science.gov (United States)

    Skorpik, James R.; Dodson, Michael G.

    1999-01-01

    The present invention is directed toward monitoring a thermally driven gas evolving chemical reaction with an acoustic apparatus. Signals from the acoustic apparatus are used to control a heater to prevent a run-away condition. A digestion module in combination with a robotic arm further automate physical handling of sample material reaction vessels. The invention is especially useful for carrying out sample procedures defined in EPA Methods SW-846.

  5. Improving catalytic selectivity through control of adsorption orientation

    Science.gov (United States)

    Pang, Simon H.

    In this thesis, we present an investigation, starting from surface science experiments, leading to design of supported catalysts, of how adsorption orientation can be used to affect reaction selectivity of highly functional molecules. The surface chemistry of furfuryl alcohol and benzyl alcohol and their respective aldehydes was studied on a Pd(111) single-crystal surface under ultra-high vacuum conditions. Temperature-programmed desorption experiments showed that synergistic chemistry existed between the aromatic ring and the oxygen-containing functional group, each allowing the other to participate in reaction pathways that a monofunctional molecule could not. Most important of these was a deoxygenation reaction that occurred more readily when the surface was crowded by the highest exposures. High-resolution electron energy loss spectroscopy revealed that at these high exposures, molecules were oriented upright on the surface, with the aromatic function extending into vacuum. In contrast, at low exposures, molecules were oriented flat on the surface. The upright adsorption geometry was correlated with deoxygenation, whereas the flat-lying geometry was correlated with decarbonylation. The insight gained from surface science experiments was utilized in catalyst design. Self-assembled monolayers of alkanethiolates were used to systematically reduce the average surface ensemble size, and the reaction selectivity was tracked. When a sparsely-packed monolayer was used, such as one formed by 1-adamantanethiol, the reactant furfural was still able to lie flat on the surface and the reaction selectivity was similar to that of the uncoated catalyst. However, when a densely-packed monolayer, formed by 1-octadecanethiol, was used, furfural was not able to adsorb flat on the surface and instead adopted an upright conformation, leading to a drastic increase in aldehyde hydrogenation and hydrodeoxygenation reaction selectivity. Using an even higher sulfur coverage from a

  6. Selective weed control using laser techniques

    OpenAIRE

    Marx, Christian; Pastrana-Perez, Julio; Hustedt, Michael; Barcikowski, Stephan; Haferkamp, Heinz; Rath, Thomas

    2012-01-01

    This contribution discusses technical and growth relevant aspects of using laser techniques for weed control. The research on thermal weed control via laser first focused on the interaction of laser beams and weed plants. Due to preliminary studies, a CO2-laser was selected for further studies with regard to the process factors laser energy, laser spot area, coverage of the weeds meristem, weed species (Amaranthus retroflexus), and weed growth stage. Thereby, the laser damage was modeled in o...

  7. Selecting Optimal Subset of Security Controls

    OpenAIRE

    Yevseyeva, I.; Basto-Fernandes, V.; Michael, Emmerich, T. M.; Moorsel, van, A.

    2015-01-01

    Open Access journal Choosing an optimal investment in information security is an issue most companies face these days. Which security controls to buy to protect the IT system of a company in the best way? Selecting a subset of security controls among many available ones can be seen as a resource allocation problem that should take into account conflicting objectives and constraints of the problem. In particular, the security of the system should be improved without hindering productivity, ...

  8. Selective Activation and Disengagement of Moral Control.

    Science.gov (United States)

    Bandura, Albert

    1990-01-01

    Analyzes psychological mechanisms by which moral control is selectively disengaged from inhumane conduct in ordinary and unusual circumstances. Explores the symptoms of moral exclusion as described in the literature. Presents categories that unify theory on moral exclusion and contribute practical classifications for use in empirical studies. (JS)

  9. Two-stage Security Controls Selection

    NARCIS (Netherlands)

    Yevseyeva, I.; Basto, Fernandes V.; Moorsel, van A.; Janicke, H.; Michael, Emmerich T. M.

    2016-01-01

    To protect a system from potential cyber security breaches and attacks, one needs to select efficient security controls, taking into account technical and institutional goals and constraints, such as available budget, enterprise activity, internal and external environment. Here we model the security

  10. Domain-Specific Control of Selective Attention

    Science.gov (United States)

    Lin, Szu-Hung; Yeh, Yei-Yu

    2014-01-01

    Previous research has shown that loading information on working memory affects selective attention. However, whether the load effect on selective attention is domain-general or domain-specific remains unresolved. The domain-general effect refers to the findings that load in one content (e.g. phonological) domain in working memory influences processing in another content (e.g., visuospatial) domain. Attentional control supervises selection regardless of information domain. The domain-specific effect refers to the constraint of influence only when maintenance and processing operate in the same domain. Selective attention operates in a specific content domain. This study is designed to resolve this controversy. Across three experiments, we manipulated the type of representation maintained in working memory and the type of representation upon which the participants must exert control to resolve conflict and select a target into the focus of attention. In Experiments 1a and 1b, participants maintained digits and nonverbalized objects, respectively, in working memory while selecting a target in a letter array. In Experiment 2, we presented auditory digits with a letter flanker task to exclude the involvement of resource competition within the same input modality. In Experiments 3a and 3b, we replaced the letter flanker task with an object flanker task while manipulating the memory load on object and digit representation, respectively. The results consistently showed that memory load modulated distractibility only when the stimuli of the two tasks were represented in the same domain. The magnitude of distractor interference was larger under high load than under low load, reflecting a lower efficacy of information prioritization. When the stimuli of the two tasks were represented in different domains, memory load did not modulate distractibility. Control of processing priority in selective attention demands domain-specific resources. PMID:24866977

  11. Selecting RMF Controls for National Security Systems

    Energy Technology Data Exchange (ETDEWEB)

    Witzke, Edward L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-08-01

    In 2014, the United States Department of Defense started tra nsitioning the way it performs risk management and accreditation of informatio n systems to a process entitled Risk Management Framework for DoD Information Technology or RMF for DoD IT. There are many more security and privacy contro ls (and control enhancements) from which to select in RMF, than there w ere in the previous Information Assurance process. This report is an attempt t o clarify the way security controls and enhancements are selected. After a brief overview and comparison of RMF for DoD I T with the previously used process, this report looks at the determination of systems as National Security Systems (NSS). Once deemed to be an NSS, this report addr esses the categorization of the information system with respect to impact level s of the various security objectives and the selection of an initial baseline o f controls. Next, the report describes tailoring the controls through the use of overl ays and scoping considerations. Finally, the report discusses organizatio n-defined values for tuning the security controls to the needs of the information system.

  12. Selective population of high-j states via heavy-ion-induced transfer reactions

    International Nuclear Information System (INIS)

    Bond, P.D.

    1982-01-01

    One of the early hopes of heavy-ion-induced transfer reactions was to populate states not seen easily or at all by other means. To date, however, I believe it is fair to say that spectroscopic studies of previously unknown states have had, at best, limited success. Despite the early demonstration of selectivity with cluster transfer to high-lying states in light nuclei, the study of heavy-ion-induced transfer reactions has emphasized the reaction mechanism. The value of using two of these reactions for spectroscopy of high spin states is demonstrated: 143 Nd( 16 O, 15 O) 144 Nd and 170 Er( 16 O, 15 Oγ) 171 Er

  13. Reaction parameters for controlled sonosynthesis of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez M, A. L. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Colon esq. Paseo Tollocan s/n, 50120 Toluca, Estado de Mexico (Mexico); Cabrera L, L. I. [UNAM-UAEM, Centro Conjunto de Investigacion en Quimica Sustentable, Km 14.5 Carretera Toluca-Atlacomulco, 50200 San Cayetano-Toluca, Estado de Mexico (Mexico)

    2015-07-01

    The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 k Hz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method. Characterization techniques used: Fourier transform infrared spectra (Ftir), X-ray diffraction and Atomic Force Microscope was used in order to determine particle size of the synthetic product of reaction M10c by tapping mode. (Author)

  14. Reaction parameters for controlled sonosynthesis of gold nanoparticles

    International Nuclear Information System (INIS)

    Gonzalez M, A. L.; Cabrera L, L. I.

    2015-01-01

    The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 k Hz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method. Characterization techniques used: Fourier transform infrared spectra (Ftir), X-ray diffraction and Atomic Force Microscope was used in order to determine particle size of the synthetic product of reaction M10c by tapping mode. (Author)

  15. Kinetics of diffusion-controlled and ballistically-controlled reactions

    International Nuclear Information System (INIS)

    Redner, S.

    1995-01-01

    The kinetics of diffusion-controlled two-species annihilation, A+B → O and single-species ballistically-controlled annihilation, A+A → O are investigated. For two-species annihilation, we describe the basic mechanism that leads to the formation of a coarsening mosaic of A- and B-domains. The implications of this picture on the distribution of reactants is discussed. For ballistic annihilation, dimensional analysis shows that the concentration and rms velocity decay as c∼t -α and v∼t -β , respectively, with α+β = 1 in any spatial dimension. Analysis of the Boltzmann equation for the evolution of the velocity distribution yields accurate predictions for the kinetics. New phenomena associated with discrete initial velocity distributions and with mixed ballistic and diffusive reactant motion are also discussed. (author)

  16. Reaction-diffusion systems in intracellular molecular transport and control.

    Science.gov (United States)

    Soh, Siowling; Byrska, Marta; Kandere-Grzybowska, Kristiana; Grzybowski, Bartosz A

    2010-06-07

    Chemical reactions make cells work only if the participating chemicals are delivered to desired locations in a timely and precise fashion. Most research to date has focused on active-transport mechanisms, although passive diffusion is often equally rapid and energetically less costly. Capitalizing on these advantages, cells have developed sophisticated reaction-diffusion (RD) systems that control a wide range of cellular functions-from chemotaxis and cell division, through signaling cascades and oscillations, to cell motility. These apparently diverse systems share many common features and are "wired" according to "generic" motifs such as nonlinear kinetics, autocatalysis, and feedback loops. Understanding the operation of these complex (bio)chemical systems requires the analysis of pertinent transport-kinetic equations or, at least on a qualitative level, of the characteristic times of the constituent subprocesses. Therefore, in reviewing the manifestations of cellular RD, we also describe basic theory of reaction-diffusion phenomena.

  17. Artificial control of biocatalytic reaction; Seitai shokubai hanno no jin`iteki seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K. [Kyoto University, Kyoto (Japan). Institute for Chemical Research

    1997-08-25

    Selective composition of optically active compounds by use of biocatalysts is discussed. No search is made for any particular microbes or enzymes, but predetermined ones are used. For an increase in the selective yield of L-type carnitine by reducing 4-chloroacetoacetic acid ester using baker`s yeast, the ester length should be enlarged to that of octyl ester. Just as in this case, steric control by ground substance modification is often effective. Lipase helps on esterification which is contrary to hydrolysis in an organic solvent and, even in the optical division in this process, steric control by ground substance modification (for example by changing the structure of the acyl section) is effective. Immobilization of biocatalysts for use in reaction occasionally exerts some effect on stereoselectivity. Two types of enzymes may be participating in a reaction and inhibiting selectivity, and then a two-layer system of water and organic solvent may be effective in performing steric control over the situation. Another measure is to inhibit the activity of either of the two enzymes by use of a selective inhibitor utilizing enzyme reaction. The kind of solvent is also an influential factor. 11 refs., 7 figs.

  18. Control of transversal instabilities in reaction-diffusion systems

    Science.gov (United States)

    Totz, Sonja; Löber, Jakob; Totz, Jan Frederik; Engel, Harald

    2018-05-01

    In two-dimensional reaction-diffusion systems, local curvature perturbations on traveling waves are typically damped out and vanish. However, if the inhibitor diffuses much faster than the activator, transversal instabilities can arise, leading from flat to folded, spatio-temporally modulated waves and to spreading spiral turbulence. Here, we propose a scheme to induce or inhibit these instabilities via a spatio-temporal feedback loop. In a piecewise-linear version of the FitzHugh–Nagumo model, transversal instabilities and spiral turbulence in the uncontrolled system are shown to be suppressed in the presence of control, thereby stabilizing plane wave propagation. Conversely, in numerical simulations with the modified Oregonator model for the photosensitive Belousov–Zhabotinsky reaction, which does not exhibit transversal instabilities on its own, we demonstrate the feasibility of inducing transversal instabilities and study the emerging wave patterns in a well-controlled manner.

  19. Localized temperature and chemical reaction control in nanoscale space by nanowire array.

    Science.gov (United States)

    Jin, C Yan; Li, Zhiyong; Williams, R Stanley; Lee, K-Cheol; Park, Inkyu

    2011-11-09

    We introduce a novel method for chemical reaction control with nanoscale spatial resolution based on localized heating by using a well-aligned nanowire array. Numerical and experimental analysis shows that each individual nanowire could be selectively and rapidly Joule heated for local and ultrafast temperature modulation in nanoscale space (e.g., maximum temperature gradient 2.2 K/nm at the nanowire edge; heating/cooling time chemical reactions such as polymer decomposition/cross-linking and direct and localized hydrothermal synthesis of metal oxide nanowires were demonstrated.

  20. Characterisation of hydrocarbonaceous overlayers important in metal-catalysed selective hydrogenation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lennon, David; Warringham, Robbie [School of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Guidi, Tatiana [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Parker, Stewart F., E-mail: stewart.parker@stfc.ac.uk [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2013-12-12

    Highlights: • Inelastic neutron scattering spectroscopy of a commercial dehydrogenation catalyst. • The overlayer present on the catalyst is predominantly aliphatic. • A population of strongly hydrogen bonded hydroxyls is also present. - Abstract: The hydrogenation of alkynes to alkenes over supported metal catalysts is an important industrial process and it has been shown that hydrocarbonaceous overlayers are important in controlling selectivity profiles of metal-catalysed hydrogenation reactions. As a model system, we have selected propyne hydrogenation over a commercial Pd(5%)/Al{sub 2}O{sub 3} catalyst. Inelastic neutron scattering studies show that the C–H stretching mode ranges from 2850 to 3063 cm{sup −1}, indicating the mostly aliphatic nature of the overlayer and this is supported by the quantification of the carbon and hydrogen on the surface. There is also a population of strongly hydrogen-bonded hydroxyls, their presence would indicate that the overlayer probably contains some oxygen functionality. There is little evidence for any olefinic or aromatic species. This is distinctly different from the hydrogen-poor overlayers that are deposited on Ni/Al{sub 2}O{sub 3} catalysts during methane reforming.

  1. A Selected Reaction Monitoring (SRM)-Based Method for Absolute Quantification of Aβ38, Aβ40, and Aβ42 in Cerebrospinal Fluid of Alzheimer's Disease Patients and Healthy Controls

    DEFF Research Database (Denmark)

    Pannee, Josef; Portelius, Erik; Oppermann, Madalina

    2013-01-01

    with mild to moderate dementia. Analytical characteristics of the method include a lower limit of quantification of 62.5 pg/mL for Aβ42 and coefficients of variations below 10%. In a pilot study on AD patients and controls, we verified disease-association with decreased levels of Aβ42 similar......). Samples were prepared by solid-phase extraction and quantification was performed using stable-isotope labeled Aβ peptides as internal standards. The diagnostic performance of the method was evaluated on two independent clinical materials with research volunteers who were cognitively normal and AD patients...

  2. Neural control of vascular reactions: impact of emotion and attention.

    Science.gov (United States)

    Okon-Singer, Hadas; Mehnert, Jan; Hoyer, Jana; Hellrung, Lydia; Schaare, Herma Lina; Dukart, Juergen; Villringer, Arno

    2014-03-19

    This study investigated the neural regions involved in blood pressure reactions to negative stimuli and their possible modulation by attention. Twenty-four healthy human subjects (11 females; age = 24.75 ± 2.49 years) participated in an affective perceptual load task that manipulated attention to negative/neutral distractor pictures. fMRI data were collected simultaneously with continuous recording of peripheral arterial blood pressure. A parametric modulation analysis examined the impact of attention and emotion on the relation between neural activation and blood pressure reactivity during the task. When attention was available for processing the distractor pictures, negative pictures resulted in behavioral interference, neural activation in brain regions previously related to emotion, a transient decrease of blood pressure, and a positive correlation between blood pressure response and activation in a network including prefrontal and parietal regions, the amygdala, caudate, and mid-brain. These effects were modulated by attention; behavioral and neural responses to highly negative distractor pictures (compared with neutral pictures) were smaller or diminished, as was the negative blood pressure response when the central task involved high perceptual load. Furthermore, comparing high and low load revealed enhanced activation in frontoparietal regions implicated in attention control. Our results fit theories emphasizing the role of attention in the control of behavioral and neural reactions to irrelevant emotional distracting information. Our findings furthermore extend the function of attention to the control of autonomous reactions associated with negative emotions by showing altered blood pressure reactions to emotional stimuli, the latter being of potential clinical relevance.

  3. Controlling Chemical Reactions in Confined Environments: Water Dissociation in MOF-74

    Directory of Open Access Journals (Sweden)

    Erika M. A. Fuentes-Fernandez

    2018-02-01

    Full Text Available The confined porous environment of metal organic frameworks (MOFs is an attractive system for studying reaction mechanisms. Compared to flat oxide surfaces, MOFs have the key advantage that they exhibit a well-defined structure and present significantly fewer challenges in experimental characterization. As an example of an important reaction, we study here the dissociation of water—which plays a critical role in biology, chemistry, and materials science—in MOFs and show how the knowledge of the structure in this confined environment allows for an unprecedented level of understanding and control. In particular, combining in-situ infrared spectroscopy and first-principles calculations, we show that the water dissociation reaction can be selectively controlled inside Zn-MOF-74 by alcohol, through both chemical and physical interactions. Methanol is observed to speed up water dissociation by 25% to 100%, depending on the alcohol partial pressure. On the other hand, co-adsorption of isopropanol reduces the speed of the water reaction, due mostly to steric interactions. In addition, we also investigate the stability of the product state after the water dissociation has occurred and find that the presence of additional water significantly stabilizes the dissociated state. Our results show that precise control of reactions within nano-porous materials is possible, opening the way for advances in fields ranging from catalysis to electrochemistry and sensors.

  4. Morphological impact on the reaction kinetics of size-selected cobalt oxide nanoparticles

    International Nuclear Information System (INIS)

    Bartling, Stephan; Meiwes-Broer, Karl-Heinz; Barke, Ingo; Pohl, Marga-Martina

    2015-01-01

    Apart from large surface areas, low activation energies are essential for efficient reactions, particularly in heterogeneous catalysis. Here, we show that not only the size of nanoparticles but also their detailed morphology can crucially affect reaction kinetics, as demonstrated for mass-selected, soft-landed, and oxidized cobalt clusters in a 6 nm to 18 nm size range. The method of reflection high-energy electron diffraction is extended to the quantitative determination of particle activation energies which is applied for repeated oxidation and reduction cycles at the same particles. We find unexpectedly small activation barriers for the reduction reaction of the largest particles studied, despite generally increasing barriers for growing sizes. We attribute these observations to the interplay of reaction-specific material transport with a size-dependent inner particle morphology

  5. Runaway reactions. Part 2 Causes of Accidents in selected CSB case histories Part 2

    OpenAIRE

    GYENES ZSUZSANNA; CARSON PHILLIP

    2017-01-01

    Part 1 briefly discussed the basic thermochemistry of reactive chemicals, the statistics of accidents involving runaway reactions, and general control measures to minimise risk and mitigate the consequences. The present paper highlights the main causes of major accidents from runaway reactions with illustrative case histories to link theory and practice. It also discusses lessons learned from these accidents, which are very similar in the cases studied. The main causes are management deficien...

  6. Diffusion-controlled reactions modeling in Geant4-DNA

    Energy Technology Data Exchange (ETDEWEB)

    Karamitros, M., E-mail: matkara@gmail.com [CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, INCIA, UMR 5287, F-33400 Talence (France); Luan, S. [University of New Mexico, Department of Computer Science, Albuquerque, NM (United States); Bernal, M.A. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, SP (Brazil); Allison, J. [Geant4 Associates International Ltd (United Kingdom); Baldacchino, G. [CEA Saclay, IRAMIS, LIDYL, Radiation Physical Chemistry Group, F-91191 Gif sur Yvette Cedex (France); CNRS, UMR3299, SIS2M, F-91191 Gif sur Yvette Cedex (France); Davidkova, M. [Nuclear Physics Institute of the ASCR, Prague (Czech Republic); Francis, Z. [Saint Joseph University, Faculty of Sciences, Department of Physics, Mkalles, Beirut (Lebanon); Friedland, W. [Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg (Germany); Ivantchenko, V. [Ecoanalytica, 119899 Moscow (Russian Federation); Geant4 Associates International Ltd (United Kingdom); Ivantchenko, A. [Geant4 Associates International Ltd (United Kingdom); Mantero, A. [SwHaRD s.r.l., via Buccari 9, 16153 Genova (Italy); Nieminem, P.; Santin, G. [ESA-ESTEC, 2200 AG Noordwijk (Netherlands); Tran, H.N. [Division of Nuclear Physics and Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Stepan, V. [CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Nuclear Physics Institute of the ASCR, Prague (Czech Republic); Incerti, S., E-mail: incerti@cenbg.in2p3.fr [CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France)

    2014-10-01

    Context Under irradiation, a biological system undergoes a cascade of chemical reactions that can lead to an alteration of its normal operation. There are different types of radiation and many competing reactions. As a result the kinetics of chemical species is extremely complex. The simulation becomes then a powerful tool which, by describing the basic principles of chemical reactions, can reveal the dynamics of the macroscopic system. To understand the dynamics of biological systems under radiation, since the 80s there have been on-going efforts carried out by several research groups to establish a mechanistic model that consists in describing all the physical, chemical and biological phenomena following the irradiation of single cells. This approach is generally divided into a succession of stages that follow each other in time: (1) the physical stage, where the ionizing particles interact directly with the biological material; (2) the physico-chemical stage, where the targeted molecules release their energy by dissociating, creating new chemical species; (3) the chemical stage, where the new chemical species interact with each other or with the biomolecules; (4) the biological stage, where the repairing mechanisms of the cell come into play. This article focuses on the modeling of the chemical stage. Method This article presents a general method of speeding-up chemical reaction simulations in fluids based on the Smoluchowski equation and Monte-Carlo methods, where all molecules are explicitly simulated and the solvent is treated as a continuum. The model describes diffusion-controlled reactions. This method has been implemented in Geant4-DNA. The keys to the new algorithm include: (1) the combination of a method to compute time steps dynamically with a Brownian bridge process to account for chemical reactions, which avoids costly fixed time step simulations; (2) a k–d tree data structure for quickly locating, for a given molecule, its closest reactants. The

  7. A Rapid Selection Procedure for Simple Commercial Implementation of omega-Transaminase Reactions

    DEFF Research Database (Denmark)

    Gundersen Deslauriers, Maria; Tufvesson, Pär; Rackham, Emma J.

    2016-01-01

    A stepwise selection procedure is presented to quickly evaluate whether a given omega-transaminase reaction is suitable for a so-called "simple" scale-up for fast industrial implementation. Here "simple" is defined as a system without the need for extensive process development or specialized......, and (3) determination of product inhibition. The method is exemplified with experimental work focused on two products: 1-(4-bromophenyl)ethylamine and (S)-(+)3-amino-1-Boc-piperidine, synthesized from their corresponding pro-chiral ketones each with two alternative amine donors, propan-2-amine, and 1......-phenylethylamine. Each step of the method has a threshold value, which must be surpassed to allow "simple" implementation, helping select suitable combinations of substrates, enzymes, and donors. One reaction pair, 1-Boc-3-piperidone with propan-2-amine, met the criteria of the three-step selection procedure...

  8. Time resolved bovine host reponse to virulence factors mapped in milk by selected reaction monitoring

    DEFF Research Database (Denmark)

    Bislev, Stine Lønnerup; Kusebauch, Ulrike; Codrea, Marius Cosmin

    . In this study, we present a sensitive selected reaction monitoring (SRM) proteomics approach, targeting proteins suggested to play key roles in the bovine host response to mastitis. 17 biomarker candidates related to inflammatory response and mastitis were selected. The 17 candidate proteins were quantified......TIME RESOLVED BOVINE HOST RESPONSE TO VIRULENCE FACTORS, MAPPED IN MILK BY SELECTED REACTION MONITORING S.L. Bislev1, U. Kusebauch2, M.C. Codrea1, R. Moritz2, C.M. Røntved1, E. Bendixen1 1 Department of Animal Science, Faculty of Science and Technology, Aarhus University, Tjele, Denmark; 2...... Institute for Systems Biology, Seattle, Washington, USA Mastitis is beyond doubt the largest health problem in modern milk production. Many different pathogens can cause infections in the mammary gland, and give rise to severe toll on animal welfare, economic gain as well as on excessive use of antibiotics...

  9. Mass spectrometric studies of bimolecular reactions in a selected ion flow tube (SIFT)

    International Nuclear Information System (INIS)

    Shul, R.J.; Upschulte, B.L.; Passarella, R.; Keesee, R.G.; Castleman, A.W.

    1985-01-01

    The rate coefficients for a number of thermal energy charge transfer reactions have been obtained with a selected ion flow tube (SIFT). The reactions studied involve Ar + and Ar 2 + with a variety of neutral molecules including: O 2 , CS 2 , CO 2 , SO 2 , H 2 S, NH 3 , and SF 6 . Such reactions have been of long-standing interest in the field of gas-phase ion-molecule chemistry from both a practical and fundamental point of view. Consideration of charge transfer reactions as possible sources of chemical lasers and their role in ionospheric and interstellar chemistry account for much of the interest. Fundamentally, the mechanism involved in these reactions has yet to be definitively established. The consumption deposition of energy into internal modes and translational degrees of freedom in such reactions has also been a topic of considerable debate. The apparatus consists of five main components: an ion source, SIFT quadrupole, ion injector, flow tube, and a mass spectrometer detection system. Ions formed in a high pressure source leak into a SIFT quadrupole where they are mass selected. The primary ion of interest is then injected into the flow tube where reactions are studied. Once in the flow tube the ions are carried downstream by an inert buffer gas, either argon, nitrogen, or helium in the present study. Neutral reactant gas is added through a reactant gas inlet (RGI) at an appropriate location downstream in the flow tube, and allowed to react with the injected ions. Ions on the flow tube axis are sampled through a 1 mm orifice where they are mass analyzed by a second quadrupole mass spectrometer and detected with a channeltron electron multiplier

  10. Inflight performance of the Ulysses reaction control system

    Science.gov (United States)

    McGarry, Andrew; Berry, William; Parker, David

    1997-01-01

    The Ulysses spacecraft has been exploring the heliosphere since October 1990 in a six-year polar orbit. Despite varying operational demands, the pressure-fed monopropellant hydrazine reaction control system (RCS) has experienced few problems. The observed anomalies, having minimal operational impact, include plume impingement effects, electrical power overload effects and hydrazine gas generation effects. These anomalies are presented and discussed, with emphasis on the first observation of gas in the hydrazine propellant. The relatively low gas generation rate is attributed to: the use of high purity hydrazine; the configuration of the spin-stabilized spacecraft; the extensive use of titanium alloys; and the efficiency of the thermal control of the propellant tank which maintains a temperature of 21 C.

  11. Use of nanostructure initiator mass spectrometry (NIMS to deduce selectivity of reaction in glycoside hydrolases

    Directory of Open Access Journals (Sweden)

    Kai eDeng

    2015-10-01

    Full Text Available Chemically synthesized nanostructure-initiator mass spectrometry (NIMS probes derivatized with tetrasaccharides were used to study the reactivity of representative Clostridium thermocellum β-glucosidase, endoglucanases and cellobiohydrolase. Diagnostic patterns for reactions of these different classes of enzymes were observed. Results show sequential removal of glucose by the β-glucosidase and a progressive increase in specificity of reaction from endoglucanases to cellobiohydrolase. Time-dependent reactions of these polysaccharide-selective enzymes were modeled by numerical integration, which provides a quantitative basis to make functional distinctions among a continuum of naturally evolved catalytic properties. Consequently, our method, which combines automated protein translation with high-sensitivity and time-dependent detection of multiple products, provides a new approach to annotate glycoside hydrolase phylogenetic trees with functional measurements.

  12. Reaction mixtures formed by nitrite and selected sulfa-drugs showed mutagenicity in acidic medium

    Directory of Open Access Journals (Sweden)

    Claudia Trossero

    2009-01-01

    Full Text Available Nitrite, which is present in preserved meat and can be produced in the oral cavity by reduction of nitrate taken from vegetables, could react in stomach with nitrosatable drugs, giving genotoxic-carcinogenic N-nitroso compounds (NOC. The mutagenicity of reaction mixtures formed by sodium nitrite and selected sulfa-drugs (sulfathiazole, HST; phtalylsulfathiazole, PhST; complex Co(II-sulfathiazole, Co(II-ST in acidic medium was evaluated using the Salmonella typhimurium reverse mutation assay (Ames test, with TA98 and TA 100 strains. The reactions were carried out at room temperature, with a mole ratio [nitrite]/[sulfa-drug] > 1. The three reaction mixtures showed mutagenic effects in the considered range.

  13. Applicant reactions to social network web use in personnel selection and assessment

    Directory of Open Access Journals (Sweden)

    David Aguado

    2016-12-01

    Full Text Available Human Resource (HR professionals are increasingly using Social Networking Websites (SNWs for personnel recruitment and selection processes. However, evidence is required regarding their psychometric properties and their impact on applicant reactions. In this paper we present and discuss the results of exploring applicant reactions to either the use of a professional SNW (such as LinkedIn or a non-professional SNW (such as Facebook. A scale for assessing applicant reactions was applied to 124 professionals. The results showed more positive attitudes to the use of professional SNWs compared with non-professional SNWs. Both gender and age moderated these results, with females and young applicants having a less positive attitude than males and older participants towards the use of non-professional SNWs.

  14. Variationally optimal selection of slow coordinates and reaction coordinates in macromolecular systems

    Science.gov (United States)

    Noe, Frank

    To efficiently simulate and generate understanding from simulations of complex macromolecular systems, the concept of slow collective coordinates or reaction coordinates is of fundamental importance. Here we will introduce variational approaches to approximate the slow coordinates and the reaction coordinates between selected end-states given MD simulations of the macromolecular system and a (possibly large) basis set of candidate coordinates. We will then discuss how to select physically intuitive order paremeters that are good surrogates of this variationally optimal result. These result can be used in order to construct Markov state models or other models of the stationary and kinetics properties, in order to parametrize low-dimensional / coarse-grained model of the dynamics. Deutsche Forschungsgemeinschaft, European Research Council.

  15. Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

    Science.gov (United States)

    Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

    2016-02-05

    As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Activity and selectivity of three molybdenum catalysts for coal liquefaction reactions

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, C.W.; Pellegrino, J.L.

    The activity and selectivity of three different molybdenum catalysts for reactions occurring in coal liquefaction, specifically for hydrogenation (HYD), hydrodeoxygenation (HDO), hydrodenitrogenation (HDN), hydrodesulfurization (HDS), and hydrocracking (HYC), have been examined. The three molybdenum catalysts used were molybdenum napthenate, molybdenum on ..gamma..-alumina, and a precipitated, disordered MoS/sub 2/. Molybdenum naphthenate was most selective for HYD and HDN. All three catalysts exhibited approximately equal activity for HDS and HDO and little selectivity for HYC of alkyl bridge structures. The activity and selectivity of the three molybdenum catalysts for producing hydrocarbons and removing heteroatoms from coal during liquefaction were determined and compared. Molybdenum naphthenate was the most active catalyst for hydrocarbon production and removal of nitrogen- and oxygen-containing species during coal liquefaction. 31 refs., 4 figs., 7 tabs.

  17. The Effect of Temperature on Selectivity in the Oscillatory Mode of the Phenylacetylene Oxidative Carbonylation Reaction.

    Science.gov (United States)

    Parker, Julie; Novakovic, Katarina

    2017-08-05

    Reaction temperature plays a major role in product selectivity in the oscillatory mode of the palladium-catalyzed phenylacetylene oxidative carbonylation reaction. At 40 °C, dimethyl (2Z)-2-phenyl-2-butenedioate is the major product whereas at 0 °C the major product is 5,5-dimethoxy-3-phenyl-2(5H)-furanone. The occurrence of oscillations in pH coincides with an increase in the rate of phenylacetylene consumption and associated product formation. Experiments were performed isothermally in a reaction calorimeter to correlate reactant consumption and product formation with the occurrence of pH oscillations and the heat released by the reaction. An increase in the size of the pH drop in a single oscillation correlates with an increase in energy, indicating that this section of a single oscillation relates to reactant consumption. Based on these observations, a reaction pathway responsible for product formation is provided. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  18. Dependence and withdrawal reactions to benzodiazepines and selective serotonin reuptake inhibitors. How did the health authorities react?

    DEFF Research Database (Denmark)

    Nielsen, Margrethe; Hansen, Ebba Holme; Gøtzsche, Peter C

    2013-01-01

    Our objective was to explore communications from drug agencies about benzodiazepine dependence and selective serotonin reuptake inhibitors (SSRIs) withdrawal reactions over time.......Our objective was to explore communications from drug agencies about benzodiazepine dependence and selective serotonin reuptake inhibitors (SSRIs) withdrawal reactions over time....

  19. Selective vibrational excitation of the ethylene--fluorine reaction in a nitrogen matrix. II

    International Nuclear Information System (INIS)

    Frei, H.

    1983-01-01

    The product branching between 1,2-difluoroethane and vinyl fluoride (plus HF) of the selective vibrationally stimulated reaction of molecular fluorine with C 2 H 4 has been studied in a nitrogen matrix at 12 K and found to be the same for five different vibrational transitions of C 2 H 4 between 1896 and 4209 cm -1 . The HF/DF branching ratio of the reaction of F 2 with CH 2 CD 2 , trans-CHDCHD, and cis-CHDCHD was determined to be 1.1, independent of precursor C 2 H 2 D 2 isomer and particular mode which excited the reaction. These results, as well as the analysis of the mixtures of partially deuterated vinyl fluoride molecules produced by each C 2 H 2 D 2 isomer indicate that the product branching occurs by αβ elimination of HF(DF) from a vibrationally excited, electronic ground state 1,2-difluoroethane intermediate. Selective vibrational excitation of fluorine reactions in isotopically mixed matrices t-CHDCHD/C 2 H 4 /F 2 /N 2 and CH 2 CD 2 /C 2 H 4 /F 2 /N 2 , and in matrices C 2 H 2 /C 2 H 4 /F 2 /N 2 revealed a high degree of isotopic and molecular selectivity. The extent to which intermolecular energy transfer occurred is qualitatively explained in terms of dipole coupled vibrational energy transfer. A study of the loss of absorbance of the C 2 H 4 x F 2 pairs in case of ν 9 as a function of both the laser irradiation frequency within the absorption profile, and the ethylene concentration showed that the C 2 H 4 x F 2 absorption is inhomogeneously broadened. Substantial depletion of reactive pairs which did not absorb laser light is interpreted in terms of Forster transfer

  20. CRISPR/Cas9-Assisted Transformation-Efficient Reaction (CRATER) for Near-Perfect Selective Transformation

    Science.gov (United States)

    Rothschild, Lynn J.; Greenberg, Daniel T.; Takahashi, Jack R.; Thompson, Kirsten A.; Maheshwari, Akshay J.; Kent, Ryan E.; McCutcheon, Griffin; Shih, Joseph D.; Calvet, Charles; Devlin, Tyler D.; hide

    2015-01-01

    The CRISPR (Clustered, Regularly Interspaced, Short Palindromic Repeats)/Cas9 system has revolutionized genome editing by providing unprecedented DNA-targeting specificity. Here we demonstrate that this system can be also applied in vitro to fundamental cloning steps to facilitate efficient plasmid selection for transformation and selective gene insertion into plasmid vectors by cleaving unwanted plasmid byproducts with a single-guide RNA (sgRNA)-Cas9 nuclease complex. Using fluorescent and chromogenic proteins as reporters, we demonstrate that CRISPR/Cas9 cleavage excludes multiple plasmids as well as unwanted ligation byproducts resulting in an unprecedented increase in the transformation success rate from approximately 20% to nearly 100%. Thus, this CRISPR/Cas9-Assisted Transformation-Efficient Reaction (CRATER) protocol is a novel, inexpensive, and convenient application to conventional molecular cloning to achieve near-perfect selective transformation.

  1. Children Do Show Negative Priming: Further Evidence for Early Development of an Intact Selective Control Mechanism

    Science.gov (United States)

    Frings, Christian; Feix, Silke; Rothig, Ulrike; Bruser, Charlotte; Junge, Miriam

    2007-01-01

    Reactions to stimuli that were shortly before presented as distractors are usually slowed down; this phenomenon is known as negative priming. Negative priming is an accepted index for tapping into selective control mechanisms. Although this effect is well established for adults, it has been claimed that children do not show negative priming.…

  2. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  3. Selection of Suitable Microorganism for Biocatalytic Oxidation Reaction of Racemic Propranolol

    Directory of Open Access Journals (Sweden)

    Rahime SONGÜR

    2017-12-01

    Full Text Available Propranolol is one of the β-blockers which are pharmaceutically important, especially used for treatment of cardiovasculer disease. In this study, the production of enantiomerically pure propranolol was aimed via biocatalytic deracemization including tandem oxidation-reduction reactions of racemic propranolol. Within this content, firstly suitable microorganism for the oxidation of racemic propranolol was investigated. Alcohol dehydrogenase (ADH enzyme for oxidation of propranolol and NADH oxidase enzyme for cofactor regeneration were necessary for the oxidation reactions. For this reason, ADH and NADH oxidase enzymes activities of different microorganisms were measured to select the microorganism for using as enzyme source. These microorganisms are Lactobacillus kefir NRRL B-1839, Rhodotorula glutunis DSM 70398, Rhizopus oryzae CBS 111718, Rhizopus arhizus. The highest ADH and NADH oxidase activities were obtained for L. kefir.

  4. A consistent reaction scheme for the selective catalytic reduction of nitrogen oxides with ammonia

    DEFF Research Database (Denmark)

    Janssens, Ton V.W.; Falsig, Hanne; Lundegaard, Lars Fahl

    2015-01-01

    For the first time, the standard and fast selective catalytic reduction of NO by NH3 are described in a complete catalytic cycle, that is able to produce the correct stoichiometry, while only allowing adsorption and desorption of stable molecules. The standard SCR reaction is a coupling of the ac...... for standard SCR. Finally, the role of a nitrate/nitrite equilibrium and the possible in uence of Cu dimers and Brønsted sites are discussed, and an explanation is offered as to how a catalyst can be effective for SCR, while being a poor catalyst for NO oxidation to NO2....... spectroscopy (FTIR). A consequence of the reaction scheme is that all intermediates in fast SCR are also part of the standard SCR cycle. The calculated activation energy by density functional theory (DFT) indicates that the oxidation of an NO molecule by O2 to a bidentate nitrate ligand is rate determining...

  5. Determination of Free Fatty Acids and Triglycerides by Gas Chromatography Using Selective Esterification Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kail, Brian W; Link, Dirk D; Morreale, Bryan D

    2012-11-01

    A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography–flame ionization detection, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.

  6. Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

    Science.gov (United States)

    Murillo, Luis E.

    Studies of bimetallic systems are of great interest in catalysis due to the novel properties that they often show in comparison with the parent metals. The goals of this dissertation are: (1) to expand the studies of self-hydrogenation and hydrogenation reactions on bimetallic surfaces under ultra high vacuum conditions (UHV) using different hydrocarbon as probe molecules; (2) to attempt to correlate the surface science findings with supported catalyst studies under more realistic conditions; and (3) to investigate the competitive hydrogenation of C=C versus C=O bonds on Pt(111) modified by different 3d transition metals. Hydrogenation studies using temperature programmed desorption (TPD) on Ni/Pt(111) bimetallic surfaces have demonstrated an enhancement in the low temperature hydrogenation activity relative to that of clean Pt(111). This novel hydrogenation pathway can be achieved under UHV conditions by controlling the structures of the bimetallic surfaces. A low temperature hydrogenation activity of 1-hexene and 1-butene has been observed on a Pt-Ni-Pt(111) subsurface structure, where Ni atoms are mainly present on the second layer of the Pt(111) single crystal. These results are in agreement with previous studies of self-hydrogenation and hydrogenation of cyclohexene. However, a much higher dehydrogenation activity is observed in the reaction of cyclohexene to produce benzene, demonstrating that the hydrocarbon structure has an effect on the reaction pathways. On the other hand, self-hydrogenation of 1-butene is not observed on the Pt-Ni-Pt(111) surface, indicating that the chain length (or molecular weight) has a significant effect on the selfhydrogenation activity. The gas phase reaction of cyclohexene on Ni/Pt supported on alumina catalysts has also shown a higher self-hydrogenation activity in comparison with the same reaction performed on supported monometallic catalysts. The effects of metal loading and impregnation sequence of the metal precursors are

  7. A reaction-diffusion model to capture disparity selectivity in primary visual cortex.

    Directory of Open Access Journals (Sweden)

    Mohammed Sultan Mohiuddin Siddiqui

    Full Text Available Decades of experimental studies are available on disparity selective cells in visual cortex of macaque and cat. Recently, local disparity map for iso-orientation sites for near-vertical edge preference is reported in area 18 of cat visual cortex. No experiment is yet reported on complete disparity map in V1. Disparity map for layer IV in V1 can provide insight into how disparity selective complex cell receptive field is organized from simple cell subunits. Though substantial amounts of experimental data on disparity selective cells is available, no model on receptive field development of such cells or disparity map development exists in literature. We model disparity selectivity in layer IV of cat V1 using a reaction-diffusion two-eye paradigm. In this model, the wiring between LGN and cortical layer IV is determined by resource an LGN cell has for supporting connections to cortical cells and competition for target space in layer IV. While competing for target space, the same type of LGN cells, irrespective of whether it belongs to left-eye-specific or right-eye-specific LGN layer, cooperate with each other while trying to push off the other type. Our model captures realistic 2D disparity selective simple cell receptive fields, their response properties and disparity map along with orientation and ocular dominance maps. There is lack of correlation between ocular dominance and disparity selectivity at the cell population level. At the map level, disparity selectivity topography is not random but weakly clustered for similar preferred disparities. This is similar to the experimental result reported for macaque. The details of weakly clustered disparity selectivity map in V1 indicate two types of complex cell receptive field organization.

  8. A multi target approach to control chemical reactions in their inhomogeneous solvent environment

    International Nuclear Information System (INIS)

    Keefer, Daniel; Thallmair, Sebastian; Zauleck, Julius P P; Vivie-Riedle, Regina de

    2015-01-01

    Shaped laser pulses offer a powerful tool to manipulate molecular quantum systems. Their application to chemical reactions in solution is a promising concept to redesign chemical synthesis. Along this road, theoretical developments to include the solvent surrounding are necessary. An appropriate theoretical treatment is helpful to understand the underlying mechanisms. In our approach we simulate the solvent by randomly selected snapshots from molecular dynamics trajectories. We use multi target optimal control theory to optimize pulses for the various arrangements of explicit solvent molecules simultaneously. This constitutes a major challenge for the control algorithm, as the solvent configurations introduce a large inhomogeneity to the potential surfaces. We investigate how the algorithm handles the new challenges and how well the controllability of the system is preserved with increasing complexity. Additionally, we introduce a way to statistically estimate the efficiency of the optimized laser pulses in the complete thermodynamical ensemble. (paper)

  9. Distributed BOLD-response in association cortex vector state space predicts reaction time during selective attention.

    Science.gov (United States)

    Musso, Francesco; Konrad, Andreas; Vucurevic, Goran; Schäffner, Cornelius; Friedrich, Britta; Frech, Peter; Stoeter, Peter; Winterer, Georg

    2006-02-15

    Human cortical information processing is thought to be dominated by distributed activity in vector state space (Churchland, P.S., Sejnowski, T.J., 1992. The Computational Brain. MIT Press, Cambridge.). In principle, it should be possible to quantify distributed brain activation with independent component analysis (ICA) through vector-based decomposition, i.e., through a separation of a mixture of sources. Using event-related functional magnetic resonance imaging (fMRI) during a selective attention-requiring task (visual oddball), we explored how the number of independent components within activated cortical areas is related to reaction time. Prior to ICA, the activated cortical areas were determined on the basis of a General linear model (GLM) voxel-by-voxel analysis of the target stimuli (checkerboard reversal). Two activated cortical areas (temporoparietal cortex, medial prefrontal cortex) were further investigated as these cortical regions are known to be the sites of simultaneously active electromagnetic generators which give rise to the compound event-related potential P300 during oddball task conditions. We found that the number of independent components more strongly predicted reaction time than the overall level of "activation" (GLM BOLD-response) in the left temporoparietal area whereas in the medial prefrontal cortex both ICA and GLM predicted reaction time equally well. Comparable correlations were not seen when principle components were used instead of independent components. These results indicate that the number of independently activated components, i.e., a high level of cortical activation complexity in cortical vector state space, may index particularly efficient information processing during selective attention-requiring tasks. To our best knowledge, this is the first report describing a potential relationship between neuronal generators of cognitive processes, the associated electrophysiological evidence for the existence of distributed networks

  10. Users want simple control over device selection

    NARCIS (Netherlands)

    Misker, J.M.V.; Lindenberg, J.; Neerincx, M.A.

    2005-01-01

    When users want to combine various resources in an ambient intelligent environment in an ad hoc manner, they need to be able to identify and select these resources. We conducted an experiment to study various user interaction styles for combining input and output devices in an ambient intelligent

  11. Elucidation of Mechanisms and Selectivities of Metal-Catalyzed Reactions using Quantum Chemical Methodology.

    Science.gov (United States)

    Santoro, Stefano; Kalek, Marcin; Huang, Genping; Himo, Fahmi

    2016-05-17

    Quantum chemical techniques today are indispensable for the detailed mechanistic understanding of catalytic reactions. The development of modern density functional theory approaches combined with the enormous growth in computer power have made it possible to treat quite large systems at a reasonable level of accuracy. Accordingly, quantum chemistry has been applied extensively to a wide variety of catalytic systems. A huge number of problems have been solved successfully, and vast amounts of chemical insights have been gained. In this Account, we summarize some of our recent work in this field. A number of examples concerned with transition metal-catalyzed reactions are selected, with emphasis on reactions with various kinds of selectivities. The discussed cases are (1) copper-catalyzed C-H bond amidation of indoles, (2) iridium-catalyzed C(sp(3))-H borylation of chlorosilanes, (3) vanadium-catalyzed Meyer-Schuster rearrangement and its combination with aldol- and Mannich-type additions, (4) palladium-catalyzed propargylic substitution with phosphorus nucleophiles, (5) rhodium-catalyzed 1:2 coupling of aldehydes and allenes, and finally (6) copper-catalyzed coupling of nitrones and alkynes to produce β-lactams (Kinugasa reaction). First, the methodology adopted in these studies is presented briefly. The electronic structure method in the great majority of these kinds of mechanistic investigations has for the last two decades been based on density functional theory. In the cases discussed here, mainly the B3LYP functional has been employed in conjunction with Grimme's empirical dispersion correction, which has been shown to improve the calculated energies significantly. The effect of the surrounding solvent is described by implicit solvation techniques, and the thermochemical corrections are included using the rigid-rotor harmonic oscillator approximation. The reviewed examples are chosen to illustrate the usefulness and versatility of the adopted methodology in

  12. Do candidate reactions relate to job performance or affect criterion-related validity? A multistudy investigation of relations among reactions, selection test scores, and job performance.

    Science.gov (United States)

    McCarthy, Julie M; Van Iddekinge, Chad H; Lievens, Filip; Kung, Mei-Chuan; Sinar, Evan F; Campion, Michael A

    2013-09-01

    Considerable evidence suggests that how candidates react to selection procedures can affect their test performance and their attitudes toward the hiring organization (e.g., recommending the firm to others). However, very few studies of candidate reactions have examined one of the outcomes organizations care most about: job performance. We attempt to address this gap by developing and testing a conceptual framework that delineates whether and how candidate reactions might influence job performance. We accomplish this objective using data from 4 studies (total N = 6,480), 6 selection procedures (personality tests, job knowledge tests, cognitive ability tests, work samples, situational judgment tests, and a selection inventory), 5 key candidate reactions (anxiety, motivation, belief in tests, self-efficacy, and procedural justice), 2 contexts (industry and education), 3 continents (North America, South America, and Europe), 2 study designs (predictive and concurrent), and 4 occupational areas (medical, sales, customer service, and technological). Consistent with previous research, candidate reactions were related to test scores, and test scores were related to job performance. Further, there was some evidence that reactions affected performance indirectly through their influence on test scores. Finally, in no cases did candidate reactions affect the prediction of job performance by increasing or decreasing the criterion-related validity of test scores. Implications of these findings and avenues for future research are discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved

  13. Selected aspects of tobacco control in Croatia.

    Science.gov (United States)

    Loubeau, Patricia R

    2009-03-01

    This paper seeks to outline the challenges of tobacco consumption control in the transitional economy of Croatia. It focuses on issues of taxation, high unemployment, and smuggling while attempting to meet European Union (EU) accession requirements for tobacco control legislation that reduces smoking consumption. The issue of tobacco control is not a simple one and requires a multi-pronged approach. While Croatia has made good progress in adopting legislation, it needs to strengthen its efforts both in terms of enforcement and increased taxation of cigarettes.

  14. The influence of oscillations on product selectivity during the palladium-catalysed phenylacetylene oxidative carbonylation reaction.

    Science.gov (United States)

    Novakovic, Katarina; Grosjean, Christophe; Scott, Stephen K; Whiting, Andrew; Willis, Mark J; Wright, Allen R

    2008-02-07

    This paper reports on the influence of oscillations on product selectivity as well as the dynamics of product formation during the palladium-catalysed phenylacetylene oxidative carbonylation reaction in a catalytic system (PdI2, KI, Air, NaOAc in methanol). The occurrence of the pH oscillations is related to PdI2 granularity and the initial pH drop after phenylacetylene addition. To achieve pH and reaction exotherm oscillations regulation of the amount of PdI2 is required, ensuring that the initial pH does not fall significantly below 1 after phenylacetylene addition. Experiments in both oscillatory and non-oscillatory pH regimes were performed in an HEL SIMULAR reaction calorimeter with the concentration-time profiles measured using a GC-MS. It is demonstrated that when operating in an oscillatory pH regime product formation may be suppressed until oscillations occur after which there is a steep increase in the formation of Z-2-phenyl-but-2-enedioic acid dimethyl ester. When operating in non-oscillatory pH mode the products are formed steadily over time with the main products being Z-2-phenyl-but-2-enedioic acid dimethyl ester, 2-phenyl-acrylic acid methyl ester and E-3-phenyl-acrylic acid methyl ester.

  15. Directional Track Selection Technique in CR39 SSNTD for lowyield reaction experiments

    Science.gov (United States)

    Ingenito, Francesco; Andreoli, Pierluigi; Batani, Dimitri; Bonasera, Aldo; Boutoux, Guillaume; Burgy, Frederic; Cipriani, Mattia; Consoli, Fabrizio; Cristofari, Giuseppe; De Angelis, Riccardo; Di Giorgio, Giorgio; Ducret, Jean Eric; Giulietti, Danilo; Jakubowska, Katarzyna

    2018-01-01

    There is a great interest in the study of p-11B aneutronic nuclear fusion reactions, both for energy production and for determination of fusion cross-sections at low energies. In this context we performed experiments at CELIA in which energetic protons, accelerated by the laser ECLIPSE, were directed toward a solid Boron target. Because of the small cross-sections at these energies the number of expected reactions is low. CR39 Solid-State Nuclear Track Detectors (SSNTD) were used to detect the alpha particles produced. Because of the low expected yield, it is difficult to discriminate the tracks due to true fusion products from those due to natural background in the CR39. To this purpose we developed a methodology of particle recognition according to their direction with respect to the detector normal, able to determine the position of their source. We applied this to the specific experiment geometry, so to select from all the tracks those due to particles coming from the region of interaction between accelerated protons and solid boron target. This technique can be of great help on the analysis of SSNTD in experiments with low yield reactions, but can be also generally applied to any experiment where particles reach the track detector with known directions, and for example to improve the detection limit of particle spectrometers using CR39.

  16. Advancing the sensitivity of selected reaction monitoring-based targeted quantitative proteomics

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Tujin; Su, Dian; Liu, Tao; Tang, Keqi; Camp, David G.; Qian, Weijun; Smith, Richard D.

    2012-04-01

    Selected reaction monitoring (SRM)—also known as multiple reaction monitoring (MRM)—has emerged as a promising high-throughput targeted protein quantification technology for candidate biomarker verification and systems biology applications. A major bottleneck for current SRM technology, however, is insufficient sensitivity for e.g., detecting low-abundance biomarkers likely present at the pg/mL to low ng/mL range in human blood plasma or serum, or extremely low-abundance signaling proteins in the cells or tissues. Herein we review recent advances in methods and technologies, including front-end immunoaffinity depletion, fractionation, selective enrichment of target proteins/peptides or their posttranslational modifications (PTMs), as well as advances in MS instrumentation, which have significantly enhanced the overall sensitivity of SRM assays and enabled the detection of low-abundance proteins at low to sub- ng/mL level in human blood plasma or serum. General perspectives on the potential of achieving sufficient sensitivity for detection of pg/mL level proteins in plasma are also discussed.

  17. Demonstration of a Non-Toxic Reaction Control Engine

    Science.gov (United States)

    Robinson, Philip J.; Turpin, Alicia A.; Veith, Eric M.

    2007-01-01

    T:hree non-toxic demonstration reaction control engines (RCE) were successfully tested at the Aerojet Sacramento facility under a technology contract sponsored by the National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC). The goals of the NASA MSFC contract (NAS8-01109) were to develop and expand the technical maturity of a non-toxic, on-orbit auxiliary propulsion system (APS) thruster under the auspices of the Exploration Systems Mission Directorate. The demonstration engine utilized Liquid Oxygen (LOX) and Ethanol as propellants to produce 870 lbf thrust. The Aerojet RCE's were successfully acceptance tested over a broad range of operating conditions. Steady state tests evaluated engine response to varying chamber pressures and mixture ratios. In addition to the steady state tests, a variety of pulsing tests were conducted over a wide range of electrical pulse widths (EPW). Each EPW condition was also tested over a range of percent duty cycles (DC), and bit impulse and pulsing specific impulse were determined for each of these conditions. Subsequent to acceptance testing at Aerojet, these three engines were delivered to the NASA White Sands Test Facility (WSTF) in April 2005 for incorporation into a cryogenic Auxiliary Propulsion System Test Bed (APSTB). The APSTB is a test article that will be utilized in an altitude test cell to simulate anticipated mission applications. The objectives of this APSTB testing included evaluation of engine performance over an extended duty cycle map of propellant pressure and temperature, as well as engine and system performance at typical mission duty cycles over extended periods of time. This paper provides acceptance test results and a status of the engine performance as part of the system level testing.

  18. Fairness reactions to personnel selection methods: An international comparison between the Netherlands, the United States, France, Spain, Portugal, and Singapore

    NARCIS (Netherlands)

    Anderson, N.; Witvliet, C.

    2008-01-01

    This paper reports reactions to employee selection methods in the Netherlands and compares these findings internationally against six other previously published samples covering the United States, France, Spain, Portugal, and Singapore. A sample of 167 participants rated 10 popular assessment

  19. Catalysts synthesized by selective deposition of Fe onto Pt for the water-gas shift reaction

    Energy Technology Data Exchange (ETDEWEB)

    Aragao, Isaias Barbosa; Ro, Insoo; Liu, Yifei; Ball, Madelyn; Huber, George W.; Zanchet, Daniela; Dumesic, James A.

    2018-03-01

    FePt bimetallic catalysts with intimate contact between the two metals were synthesized by controlled surface reactions (CSR) of (cyclohexadiene)iron tricarbonyl with hydrogen-treated supported Pt nanoparticles. Adsorption of the iron precursor on a Pt/SiO2 catalyst was studied, showing that the Fe loading could be increased by performing multiple CSR cycles, and the efficiency of this process was linked to the renewal of adsorption sites by a reducing pretreatment. The catalytic activity of these bimetallic catalysts for the water gas shift reaction was improved due to promotion by iron, likely linked to H2O activation on FeOx species at or near the Pt surface, mostly in the (II) oxidation state.

  20. Miniature Reaction Wheel for Small Satellite Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of this project is to design, develop, demonstrate, and deliver a miniature, high torque, low-vibration reaction wheel for use on small satellites....

  1. Highly selective reactions of C(60)Cl(6) with thiols for the synthesis of functionalized [60]fullerene derivatives

    OpenAIRE

    Khakina, Ekaterina A; Yurkova, Anastasiya A; Peregudov, Alexander S; Troyanov, Sergey I; Trush, Vyacheslav V; Vovk, Andrey I; Mumyatov, Alexander V; Martynenko, Vyacheslav M; Balzarini, Jan; Troshin, Pavel A

    2012-01-01

    Chlorofullerene C(60)Cl(6) undergoes highly selective reactions with thiols forming compounds C(60)[SR](5)H with high yields. These reactions open up straightforward synthetic routes to many functionalized fullerene derivatives, e.g. water-soluble compounds showing interesting biological activities.

  2. Femtosecond laser control of chemical reaction of carbon monoxide and hydrogen

    CSIR Research Space (South Africa)

    Du Plessis, A

    2010-09-01

    Full Text Available Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable...

  3. Developing control room operator selection procedures

    International Nuclear Information System (INIS)

    Bosshardt, M.J.; Bownas, D.A.

    1979-01-01

    PDRI is performing a two-year study to identify the tasks performed and attributes required in electric power generating plant operating jobs, and focusing on the control room operator position. Approximately 65 investor-owned utilities are participating in the study

  4. Selection of Trichogramma for inundative biological control

    NARCIS (Netherlands)

    Pak, G.A.

    1988-01-01

    This thesis presents a study of the potential for biological control of lepidopterous pests on cabbage crops in the Netherlands, by means of inundative releases of the egg parasite Trichogramma (Hymenoptera, Trichogrammatidae). The objective of this study is to investigate the

  5. Selective molecular recognition, C-H bond activation, and catalysis in nanoscale reaction vessels

    Energy Technology Data Exchange (ETDEWEB)

    Fiedler, Dorothea; Leung, Dennis H.; Raymond, Kenneth N.; Bergman, Robert G.

    2004-11-27

    Supramolecular chemistry represents a way to mimic enzyme reactivity by using specially designed container molecules. We have shown that a chiral self-assembled M{sub 4}L{sub 6} supramolecular tetrahedron can encapsulate a variety of cationic guests, with varying degrees of stereoselectivity. Reactive iridium guests can be encapsulated and the C-H bond activation of aldehydes occurs, with the host cavity controlling the ability of substrates to interact with the metal center based upon size and shape. In addition, the host container can act as a catalyst by itself. By restricting reaction space and preorganizing the substrates into reactive conformations, it accelerates the sigmatropic rearrangement of enammonium cations.

  6. Selective Production of Renewable para-Xylene by Tungsten Carbide Catalyzed Atom-Economic Cascade Reactions.

    Science.gov (United States)

    Dai, Tao; Li, Changzhi; Li, Lin; Zhao, Zongbao Kent; Zhang, Bo; Cong, Yu; Wang, Aiqin

    2018-02-12

    Tungsten carbide was employed as the catalyst in an atom-economic and renewable synthesis of para-xylene with excellent selectivity and yield from 4-methyl-3-cyclohexene-1-carbonylaldehyde (4-MCHCA). This intermediate is the product of the Diels-Alder reaction between the two readily available bio-based building blocks acrolein and isoprene. Our results suggest that 4-MCHCA undergoes a novel dehydroaromatization-hydrodeoxygenation cascade process by intramolecular hydrogen transfer that does not involve an external hydrogen source, and that the hydrodeoxygenation occurs through the direct dissociation of the C=O bond on the W 2 C surface. Notably, this process is readily applicable to the synthesis of various (multi)methylated arenes from bio-based building blocks, thus potentially providing a petroleum-independent solution to valuable aromatic compounds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Oriented nano-wire formation and selective adhesion on substrates by single ion track reaction in polysilanes

    International Nuclear Information System (INIS)

    Shu Seki; Satoshi Tsukuda, Yoichi Yoshida; Seiichi Tagawa; Masaki Sugimoto; Shigeru Tanaka

    2002-01-01

    1-D nano-sized materials such as carbon nanotubes have attracted much attention as ideal quantum wires for future manufacturing techniques of nano-scaled opto-electronic devices. However it is still difficult to control the sizes, spatial distributions, or positions of nanotubes by conventional synthetic techniques to date. The MeV order heavy ion beams causes ultra-high density energy deposition which can not be realized by any other techniques (lasers, H, etc), and penetrate the polymer target straighforward as long as 1∼100 m depth. the energy deposited area produces non-homogeneous field can be controlled by changing the energy deposition rate of incident ions (LET: linear energy transfer, eV/nm). We found that cross-linking reaction of polysilane derivatives was predominantly caused and gave nano-gel in the chemical core, unlike main chain scission occurring at the outside of the area. high density energy deposition by ion beams causes non-homogeneous crosslinking reaction of polysilane derivatives within a nano-sized cylindrical area along an ion trajectory, and gives -SiC based nano-wires of which sizes (length, thickness) and number densities are completely under control by changing the parameters of incident ion beams and molecular sizes of target polymers. based on the concept pf the single track gelation, the present study demonstrates the formation of cross-linked polysilane nano-wires with the fairly controlled sizes. Recently the techniques of position-selective single ion hitting have been developed for MeV order ion beams, however it is not sufficient to control precisely the positions of the nano-wires on the substrates within sub- m area. in the present study, we report the selective adhesion of anno-wires on Si substrates by the surface treatments before coating, which enables the patterning of planted nano-wires on substrates and/or electrodes as candidates for nano-sized field emissive cathodes or electro-luminescent devices. Some examples of

  8. Selective Organic and Organometallic Reactions in Water-Soluble Host-Guest Supramolecular Systems

    Energy Technology Data Exchange (ETDEWEB)

    Pluth, Michael D.; Raymond, Kenneth N.; Bergman, Robert G.

    2008-02-16

    Inspired by the efficiency and selectivity of enzymes, synthetic chemists have designed and prepared a wide range of host molecules that can bind smaller molecules with their cavities; this area has become known as 'supramolecular' or 'host-guest' chemistry. Pioneered by Lehn, Cram, Pedersen, and Breslow, and followed up by a large number of more recent investigators, it has been found that the chemical environment in each assembly - defined by the size, shape, charge, and functional group availability - greatly influences the guest-binding characteristics of these compounds. In contrast to the large number of binding studies that have been carried out in this area, the exploration of chemistry - especially catalytic chemistry - that can take place inside supramolecular host cavities is still in its infancy. For example, until the work described here was carried out, very few examples of organometallic reactivity inside supramolecular hosts were known, especially in water solution. For that reason, our group and the group directed by Kenneth Raymond decided to take advantage of our complementary expertise and attempt to carry out metal-mediated C-H bond activation reactions in water-soluble supramolecular systems. This article begins by providing background from the Raymond group in supramolecular coordination chemistry and the Bergman group in C-H bond activation. It goes on to report the results of our combined efforts in supramolecular C-H activation reactions, followed by extensions of this work into a wider range of intracavity transformations.

  9. Computerized infrared spectroscopic study of surface reactions on selected lanthanide oxides

    International Nuclear Information System (INIS)

    Dellisante, G.N.

    1982-01-01

    The natures of adsorption sites on La 2 O 3 , Nd 2 O 3 , and selected praseodymium oxides were investigated by examining surface reactions of probe molecules using computerized transmission ir spectroscopy on unsupported samples. Additionally, the rehydration/dehydration behavior and crystallographic phase transitions of these oxides were examined in pretreatment temperature experiments involving rehydration of the sesquioxides to hydroxides by water exposure. Following rehydration of La 2 O 3 to La(OH) 3 , the effect of increasing vacuum pretreatment temperature (350 to 1000 0 C) is to gradually remove surface hydroxyl and carbonate entities (up to 650 0 C), and increase the degree of A-type crystallinity. Increasing crystallinity causes a concomitant decrease in surface oxide basicity. The removal of hydroxyl and carbonate species, as well as increases in oxide basicity, strongly correlated to increases in certain catalytic activities. The adsorption of NH 3 , CO 2 , mixtures of NH 3 and CO 2 , formic acid, acetic acid, acetaldehyde, and ethanol on the oxides was determined to weakly coordinate in Ln 3 + sites, and the surface reactions are discussed. Heating was found to desorb the adsorbed compounds and/or causes changes of the originally adsorbed form into other compounds. The effects of temperature on both adsorption and desorption are reported

  10. Optimization of ISSR-PCR reaction system and selection of primers in Bryum argenteum

    Directory of Open Access Journals (Sweden)

    Ma Xiaoying

    2017-02-01

    Full Text Available In order to determine optimum ISSR-PCR reaction system for moss Bryum argenteum,the concentrations of template DNA primers,dNTPs,Mg2+ and Taq DNA polymerase were optimized in four levels by PCR orthogonal experimental method. The appropriate primers were screened from 100 primers by temperature gradient PCR,and the optimal anneal temperature of the screened primers were determined. The results showed that the optimized 20 μL ISSR-PCR reaction system was as follows:template DNA 20 ng/20 μL,primers 0.45 μmol/L,Mg2+2.65 mmol/L,Taq DNA polymerase 0.4 U/20 μL,dNTPs 0.45 mmol/L. Using this system,50 primers with clear bands,repeatability well and polymorphism highly were selected from 100 primers. The establishment of this system,the screened primers and the annealing temperature could provide a theoretical basis for further research on the genetic diversity of bryophytes using ISSR molecular markers.

  11. The Reaction Microscope: Imaging and Pulse Shaping Control in Photodynamics

    NARCIS (Netherlands)

    Vredenborg, A.; Lehmann, C.S.; Irimia, D.; Roeterdink, W.; Janssen, M.H.M.

    2011-01-01

    Herein, we review the current capabilities and potential of advanced single-particle imaging techniques to study photodynamics in isolated molecules. These reaction microscopes are able to measure the full three-dimensional energy and angular distribution of (correlated) particles such as electrons

  12. Tunable, Chemo- and Site-Selective Nitrene Transfer Reactions through the Rational Design of Silver(I) Catalysts.

    Science.gov (United States)

    Alderson, Juliet M; Corbin, Joshua R; Schomaker, Jennifer M

    2017-09-19

    Carbon-nitrogen (C-N) bonds are ubiquitous in pharmaceuticals, agrochemicals, diverse bioactive natural products, and ligands for transition metal catalysts. An effective strategy for introducing a new C-N bond into a molecule is through transition metal-catalyzed nitrene transfer chemistry. In these reactions, a metal-supported nitrene can either add across a C═C bond to form an aziridine or insert into a C-H bond to furnish the corresponding amine. Typical catalysts for nitrene transfer include Rh 2 L n and Ru 2 L n complexes supported by bridging carboxylate and related ligands, as well as complexes based on Cu, Co, Ir, Fe, and Mn supported by porphyrins and related ligands. A limitation of metal-catalyzed nitrene transfer is the ability to predictably select which specific site will undergo amination in the presence of multiple reactive groups; thus, many reactions rely primarily on substrate control. Achieving true catalyst-control over nitrene transfer would open up exciting possibilities for flexible installation of new C-N bonds into hydrocarbons, natural product-inspired scaffolds, existing pharmaceuticals or biorenewable building blocks. Silver-catalyzed nitrene transfer enables flexible control over the position at which a new C-N bond is introduced. Ag(I) supported by simple N-donor ligands accommodates a diverse range of coordination geometries, from linear to tetrahedral to seesaw, enabling the electronic and steric parameters of the catalyst to be tuned independently. In addition, the ligand, Ag salt counteranion, Ag/ligand ratio and the solvent all influence the fluxional and dynamic behavior of Ag(I) complexes in solution. Understanding the interplay of these parameters to manipulate the behavior of Ag-nitrenes in a predictable manner is a key design feature of our work. In this Account, we describe successful applications of a variety of design principles to tunable, Ag-catalyzed aminations, including (1) changing Ag/ligand ratios to influence

  13. Oxidative Heck Reaction as a Tool for Para-selective Olefination of Aniline: A DFT Supported Mechanism.

    Science.gov (United States)

    Moghaddam, Firouz Matloubi; Pourkaveh, Raheleh; Karimi, Ashkan

    2017-10-06

    This study describes the first para-selective palladium-catalyzed alkenylation of tertiary amines. This regioselective C-H activation was conducted without any chelation moieties. A series of olefins were reacted under mild reaction conditions at 60 °C, and the corresponding products were obtained in good yields with high selectivity.

  14. A General Strategy for Nanohybrids Synthesis via Coupled Competitive Reactions Controlled in a Hybrid Process

    OpenAIRE

    Wang, Rongming; Yang, Wantai; Song, Yuanjun; Shen, Xiaomiao; Wang, Junmei; Zhong, Xiaodi; Li, Shuai; Song, Yujun

    2015-01-01

    A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesi...

  15. Design of an embedded inverse-feedforward biomolecular tracking controller for enzymatic reaction processes.

    Science.gov (United States)

    Foo, Mathias; Kim, Jongrae; Sawlekar, Rucha; Bates, Declan G

    2017-04-06

    Feedback control is widely used in chemical engineering to improve the performance and robustness of chemical processes. Feedback controllers require a 'subtractor' that is able to compute the error between the process output and the reference signal. In the case of embedded biomolecular control circuits, subtractors designed using standard chemical reaction network theory can only realise one-sided subtraction, rendering standard controller design approaches inadequate. Here, we show how a biomolecular controller that allows tracking of required changes in the outputs of enzymatic reaction processes can be designed and implemented within the framework of chemical reaction network theory. The controller architecture employs an inversion-based feedforward controller that compensates for the limitations of the one-sided subtractor that generates the error signals for a feedback controller. The proposed approach requires significantly fewer chemical reactions to implement than alternative designs, and should have wide applicability throughout the fields of synthetic biology and biological engineering.

  16. Reaction time, impulsivity, and attention in hyperactive children and controls: a video game technique.

    Science.gov (United States)

    Mitchell, W G; Chavez, J M; Baker, S A; Guzman, B L; Azen, S P

    1990-07-01

    Maturation of sustained attention was studied in a group of 52 hyperactive elementary school children and 152 controls using a microcomputer-based test formatted to resemble a video game. In nonhyperactive children, both simple and complex reaction time decreased with age, as did variability of response time. Omission errors were extremely infrequent on simple reaction time and decreased with age on the more complex tasks. Commission errors had an inconsistent relationship with age. Hyperactive children were slower, more variable, and made more errors on all segments of the game than did controls. Both motor speed and calculated mental speed were slower in hyperactive children, with greater discrepancy for responses directed to the nondominant hand, suggesting that a selective right hemisphere deficit may be present in hyperactives. A summary score (number of individual game scores above the 95th percentile) of 4 or more detected 60% of hyperactive subjects with a false positive rate of 5%. Agreement with the Matching Familiar Figures Test was 75% in the hyperactive group.

  17. Internal Diffusion-Controlled Enzyme Reaction: The Acetylcholinesterase Kinetics.

    Science.gov (United States)

    Lee, Sangyun; Kim, Ji-Hyun; Lee, Sangyoub

    2012-02-14

    Acetylcholinesterase is an enzyme with a very high turnover rate; it quenches the neurotransmitter, acetylcholine, at the synapse. We have investigated the kinetics of the enzyme reaction by calculating the diffusion rate of the substrate molecule along an active site channel inside the enzyme from atomic-level molecular dynamics simulations. In contrast to the previous works, we have found that the internal substrate diffusion is the determinant of the acetylcholinesterase kinetics in the low substrate concentration limit. Our estimate of the overall bimolecular reaction rate constant for the enzyme is in good agreement with the experimental data. In addition, the present calculation provides a reasonable explanation for the effects of the ionic strength of solution and the mutation of surface residues of the enzyme. The study suggests that internal diffusion of the substrate could be a key factor in understanding the kinetics of enzymes of similar characteristics.

  18. Tuning a Protein-Labeling Reaction to Achieve Highly Site Selective Lysine Conjugation.

    Science.gov (United States)

    Pham, Grace H; Ou, Weijia; Bursulaya, Badry; DiDonato, Michael; Herath, Ananda; Jin, Yunho; Hao, Xueshi; Loren, Jon; Spraggon, Glen; Brock, Ansgar; Uno, Tetsuo; Geierstanger, Bernhard H; Cellitti, Susan E

    2018-04-16

    Activated esters are widely used to label proteins at lysine side chains and N termini. These reagents are useful for labeling virtually any protein, but robust reactivity toward primary amines generally precludes site-selective modification. In a unique case, fluorophenyl esters are shown to preferentially label human kappa antibodies at a single lysine (Lys188) within the light-chain constant domain. Neighboring residues His189 and Asp151 contribute to the accelerated rate of labeling at Lys188 relative to the ≈40 other lysine sites. Enriched Lys188 labeling can be enhanced from 50-70 % to >95 % by any of these approaches: lowering reaction temperature, applying flow chemistry, or mutagenesis of specific residues in the surrounding protein environment. Our results demonstrated that activated esters with fluoro-substituted aromatic leaving groups, including a fluoronaphthyl ester, can be generally useful reagents for site-selective lysine labeling of antibodies and other immunoglobulin-type proteins. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Automated selected reaction monitoring software for accurate label-free protein quantification.

    Science.gov (United States)

    Teleman, Johan; Karlsson, Christofer; Waldemarson, Sofia; Hansson, Karin; James, Peter; Malmström, Johan; Levander, Fredrik

    2012-07-06

    Selected reaction monitoring (SRM) is a mass spectrometry method with documented ability to quantify proteins accurately and reproducibly using labeled reference peptides. However, the use of labeled reference peptides becomes impractical if large numbers of peptides are targeted and when high flexibility is desired when selecting peptides. We have developed a label-free quantitative SRM workflow that relies on a new automated algorithm, Anubis, for accurate peak detection. Anubis efficiently removes interfering signals from contaminating peptides to estimate the true signal of the targeted peptides. We evaluated the algorithm on a published multisite data set and achieved results in line with manual data analysis. In complex peptide mixtures from whole proteome digests of Streptococcus pyogenes we achieved a technical variability across the entire proteome abundance range of 6.5-19.2%, which was considerably below the total variation across biological samples. Our results show that the label-free SRM workflow with automated data analysis is feasible for large-scale biological studies, opening up new possibilities for quantitative proteomics and systems biology.

  20. Conflicts during response selection affect response programming: reactions toward the source of stimulation.

    Science.gov (United States)

    Buetti, Simona; Kerzel, Dirk

    2009-06-01

    In the Simon effect, participants make a left or right keypress in response to a nonspatial attribute (e.g., color) that is presented on the left or right. Reaction times (RTs) increase when the response activated by the irrelevant stimulus location and the response retrieved by instruction are in conflict. The authors measured RTs and movement parameters (MPs) of pointing responses in a typical Simon task. Their results show that the trajectories veer toward the imperative stimulus. This bias decreased as RTs increased. The authors suggest that the time course of trajectory deviations reflects the resolution of the response conflict over time. Further, time pressure did not affect the size of the Simon effect in MPs or its time course, but strongly reduced the Simon effect in RTs. In contrast, response selection before the onset of a go signal on the left or right did not affect the Simon effect in RTs, but reduced the Simon effect in MPs and reversed the time course. The authors speculate about independent Simon effects associated with response selection and programming. (c) 2009 APA, all rights reserved.

  1. Selective scanning tunnelling microscope electron-induced reactions of single biphenyl molecules on a Si(100) surface.

    Science.gov (United States)

    Riedel, Damien; Bocquet, Marie-Laure; Lesnard, Hervé; Lastapis, Mathieu; Lorente, Nicolas; Sonnet, Philippe; Dujardin, Gérald

    2009-06-03

    Selective electron-induced reactions of individual biphenyl molecules adsorbed in their weakly chemisorbed configuration on a Si(100) surface are investigated by using the tip of a low-temperature (5 K) scanning tunnelling microscope (STM) as an atomic size source of electrons. Selected types of molecular reactions are produced, depending on the polarity of the surface voltage during STM excitation. At negative surface voltages, the biphenyl molecule diffuses across the surface in its weakly chemisorbed configuration. At positive surface voltages, different types of molecular reactions are activated, which involve the change of adsorption configuration from the weakly chemisorbed to the strongly chemisorbed bistable and quadristable configurations. Calculated reaction pathways of the molecular reactions on the silicon surface, using the nudge elastic band method, provide evidence that the observed selectivity as a function of the surface voltage polarity cannot be ascribed to different activation energies. These results, together with the measured threshold surface voltages and the calculated molecular electronic structures via density functional theory, suggest that the electron-induced molecular reactions are driven by selective electron detachment (oxidation) or attachment (reduction) processes.

  2. Metabolic control analysis of biochemical pathways based on a thermokinetic description of reaction rates

    DEFF Research Database (Denmark)

    Nielsen, Jens Bredal

    1997-01-01

    Metabolic control analysis is a powerful technique for the evaluation of flux control within biochemical pathways. Its foundation is the elasticity coefficients and the flux control coefficients (FCCs). On the basis of a thermokinetic description of reaction rates it is here shown...... that the elasticity coefficients can be calculated directly from the pool levels of metabolites at steady state. The only requirement is that one thermodynamic parameter be known, namely the reaction affinity at the intercept of the tangent in the inflection point of the curve of reaction rate against reaction...... of the thermokinetic description of reaction rates to include the influence of effecters. Here the reaction rate is written as a linear function of the logarithm of the metabolite concentrations. With this type of rate function it is shown that the approach of Delgado and Liao [Biochem. J. (1992) 282, 919-927] can...

  3. Reaction-diffusion controlled growth of complex structures

    Science.gov (United States)

    Noorduin, Willem; Mahadevan, L.; Aizenberg, Joanna

    2013-03-01

    Understanding how the emergence of complex forms and shapes in biominerals came about is both of fundamental and practical interest. Although biomineralization processes and organization strategies to give higher order architectures have been studied extensively, synthetic approaches to mimic these self-assembled structures are highly complex and have been difficult to emulate, let alone replicate. The emergence of solution patterns has been found in reaction-diffusion systems such as Turing patterns and the BZ reaction. Intrigued by this spontaneous formation of complexity we explored if similar processes can lead to patterns in the solid state. We here identify a reaction-diffusion system in which the shape of the solidified products is a direct readout of the environmental conditions. Based on insights in the underlying mechanism, we developed a toolbox of engineering strategies to deterministically sculpt patterns and shapes, and combine different morphologies to create a landscape of hierarchical multi scale-complex tectonic architectures with unprecedented levels of complexity. These findings may hold profound implications for understanding, mimicking and ultimately expanding upon nature's morphogenesis strategies, allowing the synthesis of advanced highly complex microscale materials and devices. WLN acknowledges the Netherlands Organization for Scientific Research for financial support

  4. SiC-BASED HYDROGEN SELECTIVE MEMBRANES FOR WATER-GAS-SHIFT REACTION; F

    International Nuclear Information System (INIS)

    Paul K.T. Liu

    2001-01-01

    This technical report summarizes our activities conducted in Yr II. In Yr I we successfully demonstrated the feasibility of preparing the hydrogen selective SiC membrane with a chemical vapor deposition (CVD) technique. In addition, a SiC macroporous membrane was fabricated as a substrate candidate for the proposed SiC membrane. In Yr II we have focused on the development of a microporous SiC membrane as an intermediate layer between the substrate and the final membrane layer prepared from CVD. Powders and supported thin silicon carbide films (membranes) were prepared by a sol-gel technique using silica sol precursors as the source of silicon, and phenolic resin as the source of carbon. The powders and films were prepared by the carbothermal reduction reaction between the silica and the carbon source. The XRD analysis indicates that the powders and films consist of SiC, while the surface area measurement indicates that they contain micropores. SEM and AFM studies of the same films also validate this observation. The powders and membranes were also stable under different corrosive and harsh environments. The effects of these different treatments on the internal surface area, pore size distribution, and transport properties, were studied for both the powders and the membranes using the aforementioned techniques and XPS. Finally the SiC membrane materials are shown to have satisfactory hydrothermal stability for the proposed application. In Yr III, we will focus on the demonstration of the potential benefit using the SiC membrane developed from Yr I and II for the water-gas-shift (WGS) reaction

  5. Age-related slowing of response selection and production in a visual choice reaction time task

    Directory of Open Access Journals (Sweden)

    David L Woods

    2015-04-01

    Full Text Available Aging is associated with delayed processing in choice reaction time (CRT tasks, but the processing stages most impacted by aging have not been clearly identified. Here, we analyzed CRT latencies in a computerized serial visual feature-conjunction task. Participants responded to a target letter (probability 40% by pressing one mouse button, and responded to distractor letters differing either in color, shape, or both features from the target (probabilities 20% each, by pressing the other mouse button. Stimuli were presented randomly to the left and right visual fields and stimulus onset asynchronies (SOAs were adaptively reduced following correct responses using a staircase procedure. In Experiment 1, we tested 1466 participants who ranged in age from 18 to 65 years. CRT latencies increased significantly with age (r = 0.47, 2.80 ms/year. Central processing time (CPT, isolated by subtracting simple reaction times (obtained in a companion experiment performed on the same day from CRT latencies, accounted for more than 80% of age-related CRT slowing, with most of the remaining increase in latency due to slowed motor responses. Participants were faster and more accurate when the stimulus location was spatially compatible with the mouse button used for responding, and this effect increased slightly with age. Participants took longer to respond to distractors with target color or shape than to distractors with no target features. However, the additional time needed to discriminate the more target-like distractors did not increase with age. In Experiment 2, we replicated the findings of Experiment 1 in a second population of 178 participants (ages 18-82 years. CRT latencies did not differ significantly in the two experiments, and similar effects of age, distractor similarity, and stimulus-response spatial compatibility were found. The results suggest that the age-related slowing in visual CRT latencies is largely due to delays in response selection and

  6. Applications of ultrashort shaped pulses in microscopy and for controlling chemical reactions

    International Nuclear Information System (INIS)

    Lozovoy, Vadim V.; Andegeko, Yair; Zhu Xin; Dantus, Marcos

    2008-01-01

    This article presents a new perspective on laser control based on insights into the effect of spectral phase on nonlinear optical processes. Gaining this understanding requires the systematic evaluation of the molecular response as a function of a series of pre-defined accurately shaped laser pulses. The effort required is rewarded with robust, highly reproducible, results. This approach is illustrated by results on selective two-photon excitation microscopy of biological samples, where higher signal and less photobleaching damage are achieved by accurate phase measurement and elimination of high-order phase distortions from the ultrashort laser pulses. A similar systematic approach applied to laser control of gas phase chemical reactions reveals surprising general trends. Molecular fragmentation pattern is found to be dependent on phase shaping. Differently shaped pulses with similar pulse duration have been found to produce similar fragmentation patterns. This implies that any single parameter that is proportional to the pulse duration, such as second harmonic generation intensity, allows us to predict the molecular fragmentation pattern within the experimental noise. This finding, is illustrated here for a series of isomers. Bond selectivity, coherent photochemistry and their applications are discussed in light of results from these systematic studies

  7. Diffusion-controlled reaction. V. Effect of concentration-dependent diffusion coefficient on reaction rate in graft polymerization

    International Nuclear Information System (INIS)

    Imre, K.; Odian, G.

    1979-01-01

    The effect of diffusion on radiation-initiated graft polymerization has been studied with emphasis on the single- and two-penetrant cases. When the physical properties of the penetrants are similar, the two-penetrant problems can be reduced to the single-penetrant problem by redefining the characteristic parameters of the system. The diffusion-free graft polymerization rate is assumed to be proportional to the upsilon power of the monomer concentration respectively, and, in which the proportionality constant a = k/sub p/R/sub i//sup w//k/sub t//sup z/, where k/sub p/ and k/sub t/ are the propagation and termination rate constants, respectively, and R/sub i/ is the initiation rate. The values of upsilon, w, and z depend on the particular reaction system. The results of earlier work were generalized by allowing a non-Fickian diffusion rate which predicts an essentially exponential dependence on the monomer concentration of the diffusion coefficient, D = D 0 [exp(deltaC/M)], where M is the saturation concentration. A reaction system is characterized by the three dimensionless parameters, upsilon, delta, and A = (L/2)[aM/sup (upsilon--1)//D 0 ]/sup 1/2/, where L is the polymer film thickness. Graft polymerization tends to become diffusion controlled as A increases. Larger values of delta and ν cause a reaction system to behave closer to the diffusion-free regime. Transition from diffusion-free to diffusion-controlled reaction involves changes in the dependence of the reaction rate on film thickness, initiation rate, and monomer concentration. Although the diffusion-free rate is w order in initiation rate, upsilon order in monomer, and independent of film thickness, the diffusion-controlled rate is w/2 order in initiator rate and inverse first-order in film thickness. Dependence of the diffusion-controlled rate on monomer is dependent in a complex manner on the diffusional characteristics of the reaction system. 11 figures, 4 tables

  8. Geochemical controls on shale groundwaters: Results of reaction path modeling

    International Nuclear Information System (INIS)

    Von Damm, K.L.; VandenBrook, A.J.

    1989-03-01

    The EQ3NR/EQ6 geochemical modeling code was used to simulate the reaction of several shale mineralogies with different groundwater compositions in order to elucidate changes that may occur in both the groundwater compositions, and rock mineralogies and compositions under conditions which may be encountered in a high-level radioactive waste repository. Shales with primarily illitic or smectitic compositions were the focus of this study. The reactions were run at the ambient temperatures of the groundwaters and to temperatures as high as 250/degree/C, the approximate temperature maximum expected in a repository. All modeling assumed that equilibrium was achieved and treated the rock and water assemblage as a closed system. Graphite was used as a proxy mineral for organic matter in the shales. The results show that the presence of even a very small amount of reducing mineral has a large influence on the redox state of the groundwaters, and that either pyrite or graphite provides essentially the same results, with slight differences in dissolved C, Fe and S concentrations. The thermodynamic data base is inadequate at the present time to fully evaluate the speciation of dissolved carbon, due to the paucity of thermodynamic data for organic compounds. In the illitic cases the groundwaters resulting from interaction at elevated temperatures are acid, while the smectitic cases remain alkaline, although the final equilibrium mineral assemblages are quite similar. 10 refs., 8 figs., 15 tabs

  9. Role of institutional controls in selection of remedial measures

    International Nuclear Information System (INIS)

    Bakr, A.A.; Agoston, E.N.; McLeod, R.V.; Hicks, H.T.

    1992-01-01

    This paper explores the regulatory intent of CERCLA's definition and applicability of institutional controls at hazardous substance release sites undergoing remedial action and institutional controls that have been defined and implemented at selected CERCLA (Superfund) sites in the United States. Under provisions of CERCLA, institutional controls can be components of, or supplements to, interim or final remedial measures for hazardous substance [as defined under CERCLA 101(14)] releases. The use of institutional controls has been proposed in a number of RODs for large Superfund sites (e.g., Times Beach, Missouri; the Clothier Disposal Site in Oswego County, New York; and the Wildcat Landfill in Kent County, Delaware). In these cases, the selected remedial actions combine active response measures with institutional controls to protect human health and the environment. These RODs provide insight to how widely the concept of institutional controls is used and under what conditions. The use of institutional controls at large federal facilities is also discussed

  10. Controlling selectivities in CO2 reduction through mechanistic understanding

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang; Shi, Hui; Szanyi, János

    2017-09-11

    Catalytic CO2 conversion to energy carriers and intermediates is of utmost importance to energy and environmental goals. However, the lack of fundamental understanding of the reaction mechanism renders designing a selective catalyst inefficient. We performed operando FTIR/SSITKA experiments to understand the correlation between the kinetics of product formation and that of surface species conversion during CO2 reduction over Pd/Al2O3 catalysts. We found that the rate-determining step for CO formation is the conversion of adsorbed formate, while that for CH4 formation is the hydrogenation of adsorbed carbonyl. The balance of the hydrogenation kinetics between adsorbed formates and carbonyls governs the selectivities to CH4 and CO. We demonstrated how this knowledge can be used to design catalysts to achieve high selectivities to desired products.

  11. Selective control of attention supports the positivity effect in aging.

    Directory of Open Access Journals (Sweden)

    Laura K Sasse

    Full Text Available There is emerging evidence for a positivity effect in healthy aging, which describes an age-specific increased focus on positive compared to negative information. Life-span researchers have attributed this effect to the selective allocation of cognitive resources in the service of prioritized emotional goals. We explored the basic principles of this assumption by assessing selective attention and memory for visual stimuli, differing in emotional content and self-relevance, in young and old participants. To specifically address the impact of cognitive control, voluntary attentional selection during the presentation of multiple-item displays was analyzed and linked to participants' general ability of cognitive control. Results revealed a positivity effect in older adults' selective attention and memory, which was particularly pronounced for self-relevant stimuli. Focusing on positive and ignoring negative information was most evident in older participants with a generally higher ability to exert top-down control during visual search. Our findings highlight the role of controlled selectivity in the occurrence of a positivity effect in aging. Since the effect has been related to well-being in later life, we suggest that the ability to selectively allocate top-down control might represent a resilience factor for emotional health in aging.

  12. Selective control of attention supports the positivity effect in aging.

    Science.gov (United States)

    Sasse, Laura K; Gamer, Matthias; Büchel, Christian; Brassen, Stefanie

    2014-01-01

    There is emerging evidence for a positivity effect in healthy aging, which describes an age-specific increased focus on positive compared to negative information. Life-span researchers have attributed this effect to the selective allocation of cognitive resources in the service of prioritized emotional goals. We explored the basic principles of this assumption by assessing selective attention and memory for visual stimuli, differing in emotional content and self-relevance, in young and old participants. To specifically address the impact of cognitive control, voluntary attentional selection during the presentation of multiple-item displays was analyzed and linked to participants' general ability of cognitive control. Results revealed a positivity effect in older adults' selective attention and memory, which was particularly pronounced for self-relevant stimuli. Focusing on positive and ignoring negative information was most evident in older participants with a generally higher ability to exert top-down control during visual search. Our findings highlight the role of controlled selectivity in the occurrence of a positivity effect in aging. Since the effect has been related to well-being in later life, we suggest that the ability to selectively allocate top-down control might represent a resilience factor for emotional health in aging.

  13. Efficacy and safety of topical Trikatu preparation in, relieving mosquito bite reactions: a randomized controlled trial.

    Science.gov (United States)

    Maenthaisong, Ratree; Chaiyakunapruk, Nathorn; Tiyaboonchai, Waree; Tawatsin, Apiwat; Rojanawiwat, Archawin; Thavara, Usavadee

    2014-02-01

    Trikatu is composed of dried fruits of Piper nigrum L and Piper retrofractum Vahl, and dried rhizomes of Zingiber officinale R. Although this preparation has been used to relieve pruritis, pain, and inflammation for a long time, there is no clinical evidence to confirm its efficacy and safety. Therefore, we performed a double-blind, within person-randomized controlled study of 30 healthy volunteers to determine efficacy and safety of topical Trikatu on mosquito bite reactions. All subjects were bitten by Aedes aegypti laboratory mosquitoes on their forearms and they were randomly assigned arms to apply either Trikatu or reference product on the mosquito bite papule. The main outcome was the difference of papule size reduction at 30 min, measured by a caliper, between the Trikatu and reference arms. Pruritis, redness, pain, and patient satisfaction were assessed at 15, 30, 60, 180, and 360 min as secondary outcomes. There were no significant differences between treatment and reference arms on any outcome at any time of measurement. Trikatu did not show additional effects for relieving mosquito bite reaction as compared with the reference product containing camphor, menthol, and eucalyptus. For further study, it is very important to consider a proper selection of subjects, comparator product, and concentration of extract when Trikatu preparation is investigated. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Targeted selected reaction monitoring mass spectrometric immunoassay for insulin-like growth factor 1.

    Directory of Open Access Journals (Sweden)

    Eric E Niederkofler

    Full Text Available Insulin-like growth factor 1 (IGF1 is an important biomarker of human growth disorders that is routinely analyzed in clinical laboratories. Mass spectrometry-based workflows offer a viable alternative to standard IGF1 immunoassays, which utilize various pre-analytical preparation strategies. In this work we developed an assay that incorporates a novel sample preparation method for dissociating IGF1 from its binding proteins. The workflow also includes an immunoaffinity step using antibody-derivatized pipette tips, followed by elution, trypsin digestion, and LC-MS/MS separation and detection of the signature peptides in a selected reaction monitoring (SRM mode. The resulting quantitative mass spectrometric immunoassay (MSIA exhibited good linearity in the range of 1 to 1,500 ng/mL IGF1, intra- and inter-assay precision with CVs of less than 10%, and lowest limits of detection of 1 ng/mL. The linearity and recovery characteristics of the assay were also established, and the new method compared to a commercially available immunoassay using a large cohort of human serum samples. The IGF1 SRM MSIA is well suited for use in clinical laboratories.

  15. A Nonlinear Fuel Optimal Reaction Jet Control Law

    National Research Council Canada - National Science Library

    Breitfeller, Eric

    2002-01-01

    We derive a nonlinear fuel optimal attitude control system (ACS) that drives the final state to the desired state according to a cost function that weights the final state angular error relative to the angular rate error...

  16. Mems Reaction Control and Maneuvering for Picosat beyond LEO

    Data.gov (United States)

    National Aeronautics and Space Administration — This project further develops a multi-functional SmallSat technology for low-power attitude control of picosatellites beyond low Earth orbit. The film-evaporation...

  17. Thalamic control of sensory selection in divided attention.

    Science.gov (United States)

    Wimmer, Ralf D; Schmitt, L Ian; Davidson, Thomas J; Nakajima, Miho; Deisseroth, Karl; Halassa, Michael M

    2015-10-29

    How the brain selects appropriate sensory inputs and suppresses distractors is unknown. Given the well-established role of the prefrontal cortex (PFC) in executive function, its interactions with sensory cortical areas during attention have been hypothesized to control sensory selection. To test this idea and, more generally, dissect the circuits underlying sensory selection, we developed a cross-modal divided-attention task in mice that allowed genetic access to this cognitive process. By optogenetically perturbing PFC function in a temporally precise window, the ability of mice to select appropriately between conflicting visual and auditory stimuli was diminished. Equivalent sensory thalamocortical manipulations showed that behaviour was causally dependent on PFC interactions with the sensory thalamus, not sensory cortex. Consistent with this notion, we found neurons of the visual thalamic reticular nucleus (visTRN) to exhibit PFC-dependent changes in firing rate predictive of the modality selected. visTRN activity was causal to performance as confirmed by bidirectional optogenetic manipulations of this subnetwork. Using a combination of electrophysiology and intracellular chloride photometry, we demonstrated that visTRN dynamically controls visual thalamic gain through feedforward inhibition. Our experiments introduce a new subcortical model of sensory selection, in which the PFC biases thalamic reticular subnetworks to control thalamic sensory gain, selecting appropriate inputs for further processing.

  18. Femtosecond laser induced and controlled chemical reaction of carbon monoxide and hydrogen

    CSIR Research Space (South Africa)

    Du Plessis, A

    2011-07-01

    Full Text Available Results from experiments aimed at bimolecular chemical reaction control of CO and H2 at room temperature and pressure, without any catalyst, using shaped femtosecond laser pulses are presented. A stable reaction product (CO2) was measured after...

  19. Multiphoton control of the 1,3-cyclohexadiene ring-opening reaction in the presence of competing solvent reactions.

    Science.gov (United States)

    Carroll, Elizabeth C; White, James L; Florean, Andrei C; Bucksbaum, Philip H; Sension, Roseanne J

    2008-07-31

    Although physical chemistry has often concentrated on the observation and understanding of chemical systems, the defining characteristic of chemistry remains the direction and control of chemical reactivity. Optical control of molecular dynamics, and thus of chemical reactivity provides a path to use photon energy as a smart reagent in a chemical system. In this paper, we discuss recent research in this field in the context of our studies of the multiphoton optical control of the photo-initiated ring-opening reaction of 1,3-cyclohexadiene (CHD) to form 1,3,5- cis-hexatriene (Z-HT). Closed-loop feedback and learning algorithms are able to identify pulses that increase the desired target state by as much as a factor of two. Mechanisms for control are discussed through the influence of the intensity dependence, the nonlinear power spectrum, and the projection of the pulses onto low orders of polynomial phase. Control measurements in neat solvents demonstrate that competing solvent fragmentation reactions must also be considered. In particular, multiphoton excitation of cyclohexane alone is capable of producing hexatriene. Statistical analyses of data sets obtained in learning algorithm searches in neat cyclohexane and for CHD in hexane and cyclohexane highlight the importance of linear and quadratic chirp, while demonstrating that the control features are not so easily defined. Higher order phase components are also important. On the basis of these results the involvement of low-frequency ground-state vibrational modes is proposed. When the population is transferred to the excited state, momentum along the torsional coordinate may keep the wave packet localized as it moves toward the conical intersections controlling the yield of Z-HT.

  20. Blockage-induced condensation controlled by a local reaction

    Science.gov (United States)

    Cirillo, Emilio N. M.; Colangeli, Matteo; Muntean, Adrian

    2016-10-01

    We consider the setup of stationary zero range models and discuss the onset of condensation induced by a local blockage on the lattice. We show that the introduction of a local feedback on the hopping rates allows us to control the particle fraction in the condensed phase. This phenomenon results in a current versus blockage parameter curve characterized by two nonanalyticity points.

  1. Dogs' reaction to inequity is affected by inhibitory control.

    Science.gov (United States)

    Brucks, Désirée; Range, Friederike; Marshall-Pescini, Sarah

    2017-11-17

    Inequity aversion is thought to act as a mechanism to ensure cooperation and has been studied in many different species, consistently revealing inter-individual variation. Inhibitory control has been proposed to act as one factor responsible for this variation since individuals need to inhibit performing the required action and/or refuse rewards in order to exhibit inequity aversion. Here, we investigated if dogs' sensitivity to inequity is affected by their capacity for inhibitory control, assessed in a test battery and questionnaire. Overall, dogs showing high compulsivity scores (i.e. repetitive behaviours independent of feedback) were more motivated to participate in the inequity task independent of the rewarding scheme. Dogs were more sensitive to inequity and individual contrast if they exhibited a slower decision speed in the inhibition tasks. Furthermore, less persistent and more impulsive dogs were more sensitive to reward inequity, potentially due to having a lower tolerance level for frustration. Results indicate that aspects of inhibitory control can explain the variation in dogs' inequity response, highlighting one of the mechanisms underlying responses to inequity. Emphasising the importance to design paradigms, which allow us to disentangle capacities to recognise inequity from the inability to react to it due to poor inhibitory control abilities.

  2. Context-specific control and context selection in conflict tasks.

    Science.gov (United States)

    Schouppe, Nathalie; Ridderinkhof, K Richard; Verguts, Tom; Notebaert, Wim

    2014-02-01

    This study investigated whether participants prefer contexts with relatively little cognitive conflict and whether this preference is related to context-specific control. A conflict selection task was administered in which participants had to choose between two categories that contained different levels of conflict. One category was associated with 80% congruent Stroop trials and 20% incongruent Stroop trials, while the other category was associated with only 20% congruent Stroop trials and 80% incongruent Stroop trials. As predicted, participants selected the low-conflict category more frequently, indicating that participants avoid contexts with high-conflict likelihood. Furthermore, we predicted a correlation between this preference for the low-conflict category and the control implementation associated with the categories (i.e., context-specific proportion congruency effect, CSPC effect). Results however did not show such a correlation, thereby failing to support a relationship between context control and context selection. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Selective control of photodissociation in deutereted water molecule HOD

    International Nuclear Information System (INIS)

    Adhikari, S.; Deshpande, Sarin; Sarma, Manabendra; Kurkal, Vandana; Mishra, M.K.

    2006-01-01

    Bond dissociation in the deutereted water molecule HOD has been investigated to explore the possibility of selective control of dissociation of O-H and O-D bonds using simple field profiles and initial states that do not require high overtone excitations. Preliminary results indicate that considerable selectivity in dissociation of O-H and O-D bonds can be achieved using fundamental and first overtone excitations only and use of field optimized initial state (FOIST) based scheme with appropriate choice of field parameters and initial states may enhance both selectivity and yield

  4. Competitive Association and Charge Transfer in the Reactions of NO + with some Ketones: a Select Ion Flow Drift Tube Study

    Czech Academy of Sciences Publication Activity Database

    Fairley, D. A.; Milligan, D. B.; Freeman, C. G.; McEwan, M. J.; Španěl, Patrik; Smith, D.

    1999-01-01

    Roč. 193, č. 1 (1999), s. 35-43 ISSN 1387-3806 Grant - others:Marsden Fund(NZ) - Institutional research plan: CEZ:A54/98:Z4-040-9-ii Keywords : ion-molecule reaction kinetics * selected ion flow drift tube * ternary association Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.086, year: 1999

  5. Microwave-Assisted Synthesis of Nanoporous Aluminum-Based Coordination Polymers as Catalysts for Selective Sulfoxidation Reaction

    Directory of Open Access Journals (Sweden)

    Madhan Vinu

    2017-10-01

    Full Text Available A series of aluminum-based coordination polymers or metal–organic frameworks (Al–MOFs, i.e., DUT-4, DUT-5, MIL-53, NH2-MIL-53, and MIL-100, have been facile prepared by microwave (MW-assisted reactions and used as catalysts for selective sulfoxidation reactions. The MW-assisted synthesis drastically reduced the reaction time from few days to hours. The prepared MOFs have smaller and uniform particle sizes and better yield compared to conventional hydrothermal method. Furthermore, the Al–MOFs have been successfully demonstrated as catalysts in oxidation reaction of methyl phenyl sulfide with H2O2 as oxidant, even under mild conditions, with more than 95% conversion.

  6. An Optical Biosensing Strategy Based on Selective Light Absorption and Wavelength Filtering from Chromogenic Reaction

    Directory of Open Access Journals (Sweden)

    Hyeong Jin Chun

    2018-03-01

    Full Text Available To overcome the time and space constraints in disease diagnosis via the biosensing approach, we developed a new signal-transducing strategy that can be applied to colorimetric optical biosensors. Our study is focused on implementation of a signal transduction technology that can directly translate the color intensity signals—that require complicated optical equipment for the analysis—into signals that can be easily counted with the naked eye. Based on the selective light absorption and wavelength-filtering principles, our new optical signaling transducer was built from a common computer monitor and a smartphone. In this signal transducer, the liquid crystal display (LCD panel of the computer monitor served as a light source and a signal guide generator. In addition, the smartphone was used as an optical receiver and signal display. As a biorecognition layer, a transparent and soft material-based biosensing channel was employed generating blue output via a target-specific bienzymatic chromogenic reaction. Using graphics editor software, we displayed the optical signal guide patterns containing multiple polygons (a triangle, circle, pentagon, heptagon, and 3/4 circle, each associated with a specified color ratio on the LCD monitor panel. During observation of signal guide patterns displayed on the LCD monitor panel using a smartphone camera via the target analyte-loaded biosensing channel as a color-filtering layer, the number of observed polygons changed according to the concentration of the target analyte via the spectral correlation between absorbance changes in a solution of the biosensing channel and color emission properties of each type of polygon. By simple counting of the changes in the number of polygons registered by the smartphone camera, we could efficiently measure the concentration of a target analyte in a sample without complicated and expensive optical instruments. In a demonstration test on glucose as a model analyte, we

  7. Automated selected reaction monitoring data analysis workflow for large-scale targeted proteomic studies.

    Science.gov (United States)

    Surinova, Silvia; Hüttenhain, Ruth; Chang, Ching-Yun; Espona, Lucia; Vitek, Olga; Aebersold, Ruedi

    2013-08-01

    Targeted proteomics based on selected reaction monitoring (SRM) mass spectrometry is commonly used for accurate and reproducible quantification of protein analytes in complex biological mixtures. Strictly hypothesis-driven, SRM assays quantify each targeted protein by collecting measurements on its peptide fragment ions, called transitions. To achieve sensitive and accurate quantitative results, experimental design and data analysis must consistently account for the variability of the quantified transitions. This consistency is especially important in large experiments, which increasingly require profiling up to hundreds of proteins over hundreds of samples. Here we describe a robust and automated workflow for the analysis of large quantitative SRM data sets that integrates data processing, statistical protein identification and quantification, and dissemination of the results. The integrated workflow combines three software tools: mProphet for peptide identification via probabilistic scoring; SRMstats for protein significance analysis with linear mixed-effect models; and PASSEL, a public repository for storage, retrieval and query of SRM data. The input requirements for the protocol are files with SRM traces in mzXML format, and a file with a list of transitions in a text tab-separated format. The protocol is especially suited for data with heavy isotope-labeled peptide internal standards. We demonstrate the protocol on a clinical data set in which the abundances of 35 biomarker candidates were profiled in 83 blood plasma samples of subjects with ovarian cancer or benign ovarian tumors. The time frame to realize the protocol is 1-2 weeks, depending on the number of replicates used in the experiment.

  8. The Generation of Dehydroalanine Residues in Protonated Polypeptides: Ion/Ion Reactions for Introducing Selective Cleavages

    Science.gov (United States)

    Peng, Zhou; Bu, Jiexun; McLuckey, Scott A.

    2017-09-01

    We examine a gas-phase approach for converting a subset of amino acid residues in polypeptide cations to dehydroalanine (Dha). Subsequent activation of the modified polypeptide ions gives rise to specific cleavage N-terminal to the Dha residue. This process allows for the incorporation of selective cleavages in the structural characterization of polypeptide ions. An ion/ion reaction within the mass spectrometer between a multiply protonated polypeptide and the sulfate radical anion introduces a radical site into the multiply protonated polypeptide reactant. Subsequent collisional activation of the polypeptide radical cation gives rise to radical side chain loss from one of several particular amino acid side chains (e.g., leucine, asparagine, lysine, glutamine, and glutamic acid) to yield a Dha residue. The Dha residues facilitate preferential backbone cleavages to produce signature c- and z-ions, demonstrated with cations derived from melittin, mechano growth factor (MGF), and ubiquitin. The efficiencies for radical side chain loss and for subsequent generation of specific c- and z-ions have been examined as functions of precursor ion charge state and activation conditions using cations of ubiquitin as a model for a small protein. It is noted that these efficiencies are not strongly dependent on ion trap collisional activation conditions but are sensitive to precursor ion charge state. Moderate to low charge states show the greatest overall yields for the specific Dha cleavages, whereas small molecule losses (e.g., water/ammonia) dominate at the lowest charge states and proton catalyzed amide bond cleavages that give rise to b- and y-ions tend to dominate at high charge states. [Figure not available: see fulltext.

  9. An Optical Biosensing Strategy Based on Selective Light Absorption and Wavelength Filtering from Chromogenic Reaction.

    Science.gov (United States)

    Chun, Hyeong Jin; Han, Yong Duk; Park, Yoo Min; Kim, Ka Ram; Lee, Seok Jae; Yoon, Hyun C

    2018-03-06

    To overcome the time and space constraints in disease diagnosis via the biosensing approach, we developed a new signal-transducing strategy that can be applied to colorimetric optical biosensors. Our study is focused on implementation of a signal transduction technology that can directly translate the color intensity signals-that require complicated optical equipment for the analysis-into signals that can be easily counted with the naked eye. Based on the selective light absorption and wavelength-filtering principles, our new optical signaling transducer was built from a common computer monitor and a smartphone. In this signal transducer, the liquid crystal display (LCD) panel of the computer monitor served as a light source and a signal guide generator. In addition, the smartphone was used as an optical receiver and signal display. As a biorecognition layer, a transparent and soft material-based biosensing channel was employed generating blue output via a target-specific bienzymatic chromogenic reaction. Using graphics editor software, we displayed the optical signal guide patterns containing multiple polygons (a triangle, circle, pentagon, heptagon, and 3/4 circle, each associated with a specified color ratio) on the LCD monitor panel. During observation of signal guide patterns displayed on the LCD monitor panel using a smartphone camera via the target analyte-loaded biosensing channel as a color-filtering layer, the number of observed polygons changed according to the concentration of the target analyte via the spectral correlation between absorbance changes in a solution of the biosensing channel and color emission properties of each type of polygon. By simple counting of the changes in the number of polygons registered by the smartphone camera, we could efficiently measure the concentration of a target analyte in a sample without complicated and expensive optical instruments. In a demonstration test on glucose as a model analyte, we could easily measure the

  10. Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)3 catalyst in the reaction selectivity.

    Science.gov (United States)

    Herrera Cano, Natividad; Uranga, Jorge G; Nardi, Mónica; Procopio, Antonio; Wunderlin, Daniel A; Santiago, Ana N

    2016-01-01

    An improved and greener protocol for the synthesis of benzimidazole derivatives, starting from o -phenylenediamine, with different aldehydes is reported. Double-condensation products were selectively obtained when Er(OTf) 3 was used as the catalyst in the presence of electron-rich aldehydes. Conversely, the formation of mono-condensation products was the preferred path in absence of this catalyst. One of the major advantages of these reactions was the formation of a single product, avoiding extensive isolation and purification of products, which is frequently associated with these reactions. Theoretical calculations helped to understand the different reactivity established for these reactions. Thus, we found that the charge density on the oxygen of the carbonyl group has a significant impact on the reaction pathway. For instance, electron-rich aldehydes better coordinate to the catalyst, which favours the addition of the amine group to the carbonyl group, therefore facilitating the formation of double-condensation products. Reactions with aliphatic or aromatic aldehydes were possible, without using organic solvents and in a one-pot procedure with short reaction time (2-5 min), affording single products in excellent yields (75-99%). This convenient and eco-friendly methodology offers numerous benefits with respect to other protocols reported for similar compounds.

  11. Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf3 catalyst in the reaction selectivity

    Directory of Open Access Journals (Sweden)

    Natividad Herrera Cano

    2016-11-01

    Full Text Available An improved and greener protocol for the synthesis of benzimidazole derivatives, starting from o-phenylenediamine, with different aldehydes is reported. Double-condensation products were selectively obtained when Er(OTf3 was used as the catalyst in the presence of electron-rich aldehydes. Conversely, the formation of mono-condensation products was the preferred path in absence of this catalyst. One of the major advantages of these reactions was the formation of a single product, avoiding extensive isolation and purification of products, which is frequently associated with these reactions.Theoretical calculations helped to understand the different reactivity established for these reactions. Thus, we found that the charge density on the oxygen of the carbonyl group has a significant impact on the reaction pathway. For instance, electron-rich aldehydes better coordinate to the catalyst, which favours the addition of the amine group to the carbonyl group, therefore facilitating the formation of double-condensation products.Reactions with aliphatic or aromatic aldehydes were possible, without using organic solvents and in a one-pot procedure with short reaction time (2–5 min, affording single products in excellent yields (75–99%. This convenient and eco-friendly methodology offers numerous benefits with respect to other protocols reported for similar compounds.

  12. Phenomenological description of selected elementary chemical reaction mechanisms: An information-theoretic study

    International Nuclear Information System (INIS)

    Esquivel, R.O.; Flores-Gallegos, N.; Iuga, C.; Carrera, E.M.; Angulo, J.C.; Antolin, J.

    2010-01-01

    The information-theoretic description of the course of two elementary chemical reactions allows a phenomenological description of the chemical course of the hydrogenic abstraction and the S N 2 identity reactions by use of Shannon entropic measures in position and momentum spaces. The analyses reveal their synchronous/asynchronous mechanistic behavior.

  13. Remote-controlling chemical reactions by light: towards chemistry with high spatio-temporal resolution.

    Science.gov (United States)

    Göstl, Robert; Senf, Antti; Hecht, Stefan

    2014-03-21

    The foundation of the chemical enterprise has always been the creation of new molecular entities, such as pharmaceuticals or polymeric materials. Over the past decades, this continuing effort of designing compounds with improved properties has been complemented by a strong effort to render their preparation (more) sustainable by implementing atom as well as energy economic strategies. Therefore, synthetic chemistry is typically concerned with making specific bonds and connections in a highly selective and efficient manner. However, to increase the degree of sophistication and expand the scope of our work, we argue that the modern aspiring chemist should in addition be concerned with attaining (better) control over when and where chemical bonds are being made or broken. For this purpose, photoswitchable molecular systems, which allow for external modulation of chemical reactions by light, are being developed and in this review we are covering the current state of the art of this exciting new field. These "remote-controlled synthetic tools" provide a remarkable opportunity to perform chemical transformations with high spatial and temporal resolution and should therefore allow regulating biological processes as well as material and device performance.

  14. General Attitude Control Algorithm for Spacecraft Equipped with Star Camera and Reaction Wheels

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    A configuration consisting of a star camera, four reaction wheels and magnetorquers for momentum unloading has become standard for many spacecraft missions. This popularity has motivated numerous agencies and private companies to initiate work on the design of an imbedded attitude control system...... realized on an integrated circuit. This paper considers two issues: slew maneuver with a feature of avoiding direct exposure of the camera's CCD chip to the Sun %, three-axis attitude control and optimal control torque distribution in a reaction wheel assembly. The attitude controller is synthesized...

  15. Biodegradation at Dynamic Plume Fringes: Mixing Versus Reaction Control

    Science.gov (United States)

    Cirpka, O. A.; Eckert, D.; Griebler, C.; Haberer, C.; Kürzinger, P.; Bauer, R.; Mellage, A.

    2014-12-01

    Biodegradation of continuously emitted plumes is known to be most pronounced at the plume fringe, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. Under steady-state conditions, physical mixing of contaminant and electron acceptor by transverse dispersion was shown to be the major bottleneck for biodegradation, with plume lengths scaling inversely with the bulk transverse dispersivity in quasi two-dimensional settings. Under these conditions, the presence of suitable microbes is essential but the biokinetic parameters do not play an important role. When the location of the plume shifts (caused, e.g., by a fluctuating groundwater table), however, the bacteria are no more situated at the plume fringe and biomass growth, decay, activation and deactivation determine the time lag until the fringe-controlled steady state is approached again. During this time lag, degradation is incomplete. The objective of the presented study was to analyze to which extent flow and transport dynamics diminish effectiveness of fringe-controlled biodegradation and which microbial processes and related biokinetic parameters determine the system response in overall degradation to hydraulic fluctuations. We performed experiments in quasi-two-dimensional flow through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth and maintenance (often subsumed as "biomass decay") microbial dormancy (that is, change into a metabolically inactive state) and

  16. Active control of methanol carbonylation selectivity over Au/carbon anode by electrochemical potential.

    Science.gov (United States)

    Funakawa, Akiyasu; Yamanaka, Ichiro; Otsuka, Kiyoshi

    2005-05-12

    Electrochemical oxidative carbonylation of methanol was studied over Au supported carbon anode in CO. The major carbonylation products were dimethyl oxalate (DMO) and dimethyl carbonate (DMC). The minor oxidation products were dimethoxy methane (DMM) and methyl formate (MF) from methanol and CO(2). Influences of various reaction conditions were studied on carbonylation activities and selectivities. The selectivities to DMO and DMC can be controlled by the electrochemical potential. Electrocatalysis of Au/carbon anode was studied by cyclic voltammetry (CV), stoichiometric reactions among Au(3+), methanol, and CO, and UV-vis spectra. The Au/carbon anode was characterized by XRD, SEM, and BE images before and after the carbonylation. These experimental facts strongly suggest that transition of oxidation states of Au affects changing of the carbonylation selectivities to DMO and DMC. Au(0) is the active species for the selective DMO formation by direct electrochemical carbonylation at low potentials (selective DMC formation by indirect electrochemical carbonylation through Au(3+)/Au(+) redox at high potentials (>+1.3 V).

  17. Directed surfaces structures and interfaces for enhanced electrocatalyst activity, selectivity, and stability for energy conversion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, Thomas F. [Stanford Univ., CA (United States). Dept. of Chemical Engineering. Shriram Center

    2016-04-20

    In this project, we have employed a systematic approach to develop active, selective, and stable catalyst materials for important electrochemical reactions involving energy conversion. In particular, we have focused our attention on developing active catalyst materials for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). HER: We have synthesized and investigated several highly active and acid stable non-precious metal HER catalysts, including: [Mo3S13]2- nanoclusters (Nature Chemistry, 2014) and molybdenum phosphosulfide (MoP|S) (Angewandte Chemie, 2014). We have also aimed to engineer these catalyst formulations in a membrane electrode assembly (MEA) for fundamental studies of water electrolysis at high current densities, approximately 1 A/cm2 (ChemSusChem, 2015). We furthermore investigated transition metal phosphide (TMP) catalysts for HER by a combined experimental–theoretical approach (Energy & Environmental Science, 2015). By synthesizing different TMPs and comparing experimentally determined HER activities with the hydrogen adsorption free energies, ΔGH, calculated by density functional theory, we showed that the TMPs follow a volcano relationship for the HER. Using our combined experimental–theoretical model, we predicted that the mixed metal TMP, Fe0.5Co0.5P, should have a near-optimal ΔGH. We synthesized several mixtures of Co and Fe phosphides alloys and confirmed that Fe0.5Co0.5P exhibits the highest HER activity of the investigated TMPs (Energy & Environmental Science, 2015). The understanding gained as to how to improve catalytic activity for the HER, particularly for non-precious metal materials, is important to DOE targets for sustainable H2 production. OER: We have developed a SrIrO3/IrOx catalyst for acidic conditions (submitted, 2016). The Sr

  18. Economics of selected water control technologies and their ...

    African Journals Online (AJOL)

    Using a production function, marginal productivity of farm inputs and benefit-cost analysis, we explore the economics of selected water control technologies. From the production function, all farm inputs, including irrigation water is found to have a significant and positive effect on yield. Marginal value products of farm inputs ...

  19. Solvent- and ligand-induced switch of selectivity in gold(I-catalyzed tandem reactions of 3-propargylindoles

    Directory of Open Access Journals (Sweden)

    Roberto Sanz

    2011-06-01

    Full Text Available The selectivity of our previously described gold-catalyzed tandem reaction, 1,2-indole migration followed by aura-iso-Nazarov cyclization, of 3-propargylindoles bearing (heteroaromatic substituents at both the propargylic and terminal positions, was reversed by the proper choice of the catalyst and the reaction conditions. Thus, 3-(inden-2-ylindoles, derived from an aura-Nazarov cyclization (instead of an aura-iso-Nazarov cyclization, were obtained in moderate to good yields from a variety of 3-propargylindoles.

  20. Friedel-Crafts reaction of benzyl fluorides: selective activation of C-F bonds as enabled by hydrogen bonding.

    Science.gov (United States)

    Champagne, Pier Alexandre; Benhassine, Yasmine; Desroches, Justine; Paquin, Jean-François

    2014-12-08

    A Friedel-Crafts benzylation of arenes with benzyl fluorides has been developed. The reaction produces 1,1-diaryl alkanes in good yield under mild conditions without the need for a transition metal or a strong Lewis acid. A mechanism involving activation of the C-F bond through hydrogen bonding is proposed. This mode of activation enables the selective reaction of benzylic C-F bonds in the presence of other benzylic leaving groups. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Quality indexes for selecting control materials of the nuclear reactors

    International Nuclear Information System (INIS)

    Martinez-Val, J.M.; Pena, J.; Esteban Naudin, A.

    1981-01-01

    Quality indexes are established and valued for selecting control materials, The requirements for accomplishing such purposes are explained with detailed analysis: absortion cross section must be as high as possible, adequate reactivity evolution versus depletion, good resistance to radiation, appropiate thermal stability, mechanical resistance and ductility, chemical compatibility with the environment, good heat transfer properties, abundant in the nature and low costs. At present Westinghouse desire to commercialize hafnium as control material shows the exciting task of looking for new materials controlling nuclear reactors. (auth.)

  2. Control structure selection for energy integrated distillation column

    DEFF Research Database (Denmark)

    Hansen, J.E.; Jørgensen, Sten Bay

    1998-01-01

    This paper treats a case study on control structure selection for an almost binary distillation column. The column is energy integrated with a heat pump in order to transfer heat from the condenser to the reboiler. This integrated plant configuration renders the possible control structures somewhat...... different from what is usual for binary distillation columns. Further the heat pump enables disturbances to propagate faster through the system. The plant has six possible actuators of which three must be used to stabilize the system. Hereby three actuators are left for product purity control. An MILP...

  3. Design of an embedded inverse-feedforward biomolecular tracking controller for enzymatic reaction processes

    OpenAIRE

    Foo, Mathias; Kim, Jongrae; Sawlekar, Rucha; Bates, Declan G.

    2017-01-01

    Feedback control is widely used in chemical engineering to improve the performance and robustness of chemical processes. Feedback controllers require a ‘subtractor’ that is able to compute the error between the process output and the reference signal. In the case of embedded biomolecular control circuits, subtractors designed using standard chemical reaction network theory can only realise one-sided subtraction, rendering standard controller design approaches inadequate. Here, we show how a b...

  4. Merit exponents and control area diagrams in materials selection

    International Nuclear Information System (INIS)

    Zander, Johan; Sandstroem, Rolf

    2011-01-01

    Highlights: → Merit exponents are introduced to generalise the merit indices commonly used in materials selection. → The merit exponents can rank materials in general design situations. → To allow identification of the active merit exponent(s), control area diagrams are used. → Principles for generating the control area diagrams are presented. -- Abstract: Merit indices play a fundamental role in materials selection, since they enable ranking of materials. However, the conventional formulation of merit indices is associated with severe limitations. They are dependent on the explicit solution of the variables in the equations for the constraints from the design criteria. Furthermore, it is not always easy to determine which the controlling merit index is. To enable the ranking of materials in more general design cases, merit exponents are introduced as generalisations of the merit indices. Procedures are presented for how to compute the merit exponents numerically without having to solve equations algebraically. Merit exponents (and indices) are only valid in a certain range of property values. To simplify the identification of the controlling merit exponent, it is suggested that so called control area diagrams are used. These diagrams consist of a number of domains, each showing the active constraints and the controlling merit exponent. It is shown that the merit exponents play a crucial role when the control area diagram (CAD) is set up. The principles in the paper are developed for mechanically loaded components and are illustrated for engineering beams with two or three geometric variables.

  5. Selection of input devices and controls for modern process control consoles

    International Nuclear Information System (INIS)

    Hasenfuss, O.; Zimmermann, R.

    1975-06-01

    In modern process control consoles man-machine communication is realized more and more by computer driven CRT displays, the most efficient communication system today. This paper describes the most important input devices and controls for such control consoles. A certain number of facts are given, which should be considered during the selection. The aptitude of the described devices for special tasks is discussed and recommendations are given for carrying out a selection. (orig.) [de

  6. Synchronization criteria for generalized reaction-diffusion neural networks via periodically intermittent control.

    Science.gov (United States)

    Gan, Qintao; Lv, Tianshi; Fu, Zhenhua

    2016-04-01

    In this paper, the synchronization problem for a class of generalized neural networks with time-varying delays and reaction-diffusion terms is investigated concerning Neumann boundary conditions in terms of p-norm. The proposed generalized neural networks model includes reaction-diffusion local field neural networks and reaction-diffusion static neural networks as its special cases. By establishing a new inequality, some simple and useful conditions are obtained analytically to guarantee the global exponential synchronization of the addressed neural networks under the periodically intermittent control. According to the theoretical results, the influences of diffusion coefficients, diffusion space, and control rate on synchronization are analyzed. Finally, the feasibility and effectiveness of the proposed methods are shown by simulation examples, and by choosing different diffusion coefficients, diffusion spaces, and control rates, different controlled synchronization states can be obtained.

  7. Controlling Behaviors in Middle School Youth's Dating Relationships: Reactions and Help-Seeking Behaviors

    Science.gov (United States)

    Elias-Lambert, Nada; Black, Beverly M.; Chigbu, Kingsley U.

    2014-01-01

    This exploratory study examined middle school students' (N = 380) help-seeking behaviors and other reactions to controlling behaviors in their dating relationships. Over three-fourths of the participants perpetrated and were victimized by controlling behaviors in their dating relationships. Youth used emotional/verbal and dominance/isolation forms…

  8. Employee reactions to the use of management control systems in hospitals: motivation vs. threat

    Directory of Open Access Journals (Sweden)

    Ernesto Lopez-Valeiras

    2018-03-01

    Conclusions: The results obtained contribute to creating specific knowledge on the reactions of employees to the use of management control systems in hospitals. This information may be important in adapting management control systems to the characteristics of the hospital and its employees, which may in turn contribute to reducing dysfunctional worker behavior.

  9. Two-pulse laser control of bond-selective fragmentation

    DEFF Research Database (Denmark)

    Amstrup, Bjarne; Henriksen, Niels Engholm

    1996-01-01

    We elaborate on a two-pulse (pump-pump) laser control scheme for selective bond-breaking in molecules [Amstrup and Henriksen, J. Chem. Phys. 97, 8285 (1992)]. We show, in particular, that with this scheme one can overcome the obstacle of intramolecular vibrational relaxation. As an example, we...... consider an ozone molecule with isotopic substitution, that is, (OOO)-O-16-O-16-O-18. It is shown that asymmetric bond stretching can be created in simple (intense) laser fields. We predict that an alternating high selectivity between the channels O-16+(OO)-O-16-O-18 and (OO)-O-16-O-16+ O-18 can...

  10. Fabrication of self-written waveguide in photosensitive polyimide resin by controlling photochemical reaction of photosensitizer

    International Nuclear Information System (INIS)

    Yamashita, K.; Kuro, T.; Oe, K.; Mune, K.; Tagawa, K.; Naitou, R.; Mochizuki, A.

    2004-01-01

    We have investigated optical properties of photosensitive polyimide appropriating for long self-written waveguide fabrication. From systematic measurements of absorption properties, it was found that photochemical reaction of photosensitizer dissolved in the photosensitive polyimide resins relates to transparency after the exposure, which limits the length of the fabricated self-written waveguide. By controlling the photochemical reaction, in which the photosensitive polyimide resin has sufficient transparency during exposure, four times longer self-written waveguide core was fabricated

  11. Multiple bottlenecks in hierarchical control of action sequences: what does "response selection" select in skilled typewriting?

    Science.gov (United States)

    Yamaguchi, Motonori; Logan, Gordon D; Li, Vanessa

    2013-08-01

    Does response selection select words or letters in skilled typewriting? Typing performance involves hierarchically organized control processes: an outer loop that controls word level processing, and an inner loop that controls letter (or keystroke) level processing. The present study addressed whether response selection occurs in the outer loop or the inner loop by using the psychological refractory period (PRP) paradigm in which Task1 required typing single words and Task2 required vocal responses to tones. The number of letters (string length) in the words was manipulated to discriminate selection of words from selection of keystrokes. In Experiment 1, the PRP effect depended on string length of words in Task1, suggesting that response selection occurs in the inner loop. To assess contributions of the outer loop, the influence of string length was examined in a lexical-decision task that also involves word encoding and lexical access (Experiment 2), or to-be-typed words were preexposed so outer-loop processing could finish before typing started (Experiment 3). Response time for Task2 (RT2) did not depend on string length with lexical decision, and RT2 still depended on string length with typing preexposed strings. These results support the inner-loop locus of the PRP effect. In Experiment 4, typing was performed as Task2, and the effect of string length on typing RT interacted with stimulus onset asynchrony superadditively, implying that another bottleneck also exists in the outer loop. We conclude that there are at least two bottleneck processes in skilled typewriting. 2013 APA, all rights reserved

  12. Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

    DEFF Research Database (Denmark)

    Musko, Nikolai; Jensen, Anker Degn; Baiker, Alfons

    2012-01-01

    Knowledge of the phase behaviour and composition is of paramount importance for understanding multiphase reactions. We have investigated the effect of the phase behaviour in the palladium-catalysed selective hydrogenation of 2-butenal to saturated butanal in dense carbon dioxide. The reactions were...... cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved...... performed using a 5wt% Pd on activated carbon in custom-designed high pressure autoclaves at 323K. The Cubic-Plus-Association (CPA) equation of state was employed to model the phase behaviour of the experimentally studied systems. CPA binary interaction parameters were estimated based on the experimental...

  13. Amine-Controlled Divergent Reaction: Iminolactonization and Olefination in the Presence of a Cu(I) Catalyst.

    Science.gov (United States)

    Nishikata, Takashi; Itonaga, Kohei; Yamaguchi, Norihiro; Sumimoto, Michinori

    2017-05-19

    α-Bromoamides and styrenes underwent iminolactonization reactions (carbooxygenation), in which simultaneous C-C and C-O formation occurred in the presence of a copper catalyst with triethylamine as the base. Conversely, olefination reactions occurred in the presence of a Cu catalyst with piperidine as the base. The selectivities in those reactions were very high.

  14. Orion Exploration Flight Test Reaction Control System Jet Interaction Heating Environment from Flight Data

    Science.gov (United States)

    White, Molly E.; Hyatt, Andrew J.

    2016-01-01

    The Orion Multi-Purpose Crew Vehicle (MPCV) Reaction Control System (RCS) is critical to guide the vehicle along the desired trajectory during re-­-entry. However, this system has a significant impact on the convective heating environment to the spacecraft. Heating augmentation from the jet interaction (JI) drives thermal protection system (TPS) material selection and thickness requirements for the spacecraft. This paper describes the heating environment from the RCS on the afterbody of the Orion MPCV during Orion's first flight test, Exploration Flight Test 1 (EFT-1). These jet plumes interact with the wake of the crew capsule and cause an increase in the convective heating environment. Not only is there widespread influence from the jet banks, there may also be very localized effects. The firing history during EFT-1 will be summarized to assess which jet bank interaction was measured during flight. Heating augmentation factors derived from the reconstructed flight data will be presented. Furthermore, flight instrumentation across the afterbody provides the highest spatial resolution of the region of influence of the individual jet banks of any spacecraft yet flown. This distribution of heating augmentation across the afterbody will be derived from the flight data. Additionally, trends with possible correlating parameters will be investigated to assist future designs and ground testing programs. Finally, the challenges of measuring JI, applying this data to future flights and lessons learned will be discussed.

  15. Statistical Significance of the Maximum Hardness Principle Applied to Some Selected Chemical Reactions.

    Science.gov (United States)

    Saha, Ranajit; Pan, Sudip; Chattaraj, Pratim K

    2016-11-05

    The validity of the maximum hardness principle (MHP) is tested in the cases of 50 chemical reactions, most of which are organic in nature and exhibit anomeric effect. To explore the effect of the level of theory on the validity of MHP in an exothermic reaction, B3LYP/6-311++G(2df,3pd) and LC-BLYP/6-311++G(2df,3pd) (def2-QZVP for iodine and mercury) levels are employed. Different approximations like the geometric mean of hardness and combined hardness are considered in case there are multiple reactants and/or products. It is observed that, based on the geometric mean of hardness, while 82% of the studied reactions obey the MHP at the B3LYP level, 84% of the reactions follow this rule at the LC-BLYP level. Most of the reactions possess the hardest species on the product side. A 50% null hypothesis is rejected at a 1% level of significance.

  16. Slew Maneuver Control for Spacecraft Equipped with Star Camera and Reaction Wheels

    DEFF Research Database (Denmark)

    Wisniewski, Rafal; Kulczycki, P.

    2005-01-01

    A configuration consisting of a star camera, four reaction wheels and magnetorquers for momentum unloading has become standard for many spacecraft missions. This popularity has motivated numerous agencies and private companies to initiate work on the design of an imbedded attitude control system...... realized on an integrated circuit. This paper provides an easily implementable control algorithm for this type of configuration. The paper considers two issues: slew maneuver with a feature of avoiding direct exposure of the camera's CCD chip to the Sun %, three-axis attitude control and optimal control...... torque distribution in a reaction wheel assembly. The attitude controller is synthesized applying the energy shaping technique, where the desired potential function is carefully designed using a physical insight into the nature of the problem. The system stability is thoroughly analyzed and the control...

  17. Reactions of CF3O radicals with selected alkenes and aromatics under atmospheric conditions

    DEFF Research Database (Denmark)

    Kelly, C.; Sidebottom, H.W.; Treacy, J.

    1994-01-01

    Rate data for the reactions of CF3O radicals with alkenes and aromatic compounds have been determined at 298 K using a relative rate method. The data are analyzed in terms of structure-reactivity relationships, and their importance to the atmospheric chemistry of CF3O discussed.......Rate data for the reactions of CF3O radicals with alkenes and aromatic compounds have been determined at 298 K using a relative rate method. The data are analyzed in terms of structure-reactivity relationships, and their importance to the atmospheric chemistry of CF3O discussed....

  18. Supercritical carbon dioxide as an innovative reaction medium for selective oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Loeker, F.; Leitner, W. [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)

    1998-12-31

    Although the catalytic efficiency of all catalytic oxidation processes studied in scCO{sub 2} up to now is far from being satisfactory, the principle possibility to carry out such reactions in this medium is clearly evident. Future research in our group will be directed towards the development of homogeneous and heterogeneous catalysts that are adopted to the special requirements of both the oxidation process and the supercritical reaction medium. Preliminary results from these studies regarding the epoxidation of olefins with molecular oxygen as oxidant will be presented on the conference poster. (orig.)

  19. Kinetics and selectivity of the oxidation of methylbenzenes in Co(III)-CH3COOH-CF3COOH solutions. Comparison with nitration and hydroxylation reactions

    International Nuclear Information System (INIS)

    Rudakov, E.S.; Lobachev, V.L.

    1989-01-01

    Data have been obtained concerning the kinetics, substrate selectivity, and kinetic isotope effect for the first stage in the oxidation of a series of arenes, from benzene to hexamethylbenzene, by Co(III) acetate in CH 3 COOH-CF 3 COOH (1.9 M) solutions at 25 degree C. A similarity was noted between substrate selectivity for reactions of alkylbenzenes with Co(III) and electrophilic nitration reactions, which occur via an electron transfer step. It was also found that substrate selectivity for these reactions differs significantly from that found for electrophilic hydroxylation reactions, which occur via an intermediate slow step involving σ-complex formation

  20. Investigating gaze-controlled input in a cognitive selection test

    OpenAIRE

    Gayraud, Katja; Hasse, Catrin; Eißfeldt, Hinnerk; Pannasch, Sebastian

    2017-01-01

    In the field of aviation, there is a growing interest in developing more natural forms of interaction between operators and systems to enhance safety and efficiency. These efforts also include eye gaze as an input channel for human-machine interaction. The present study investigates the application of gaze-controlled input in a cognitive selection test called Eye Movement Conflict Detection Test. The test enables eye movements to be studied as an indicator for psychological test performance a...

  1. The Effects of Heat Stress on Selective Attention and Reaction Time among Workers of a Hot Industry: Application of Computerized Version of Stroop Test

    Directory of Open Access Journals (Sweden)

    F. Golbabaei

    2015-04-01

    .Conclusion: According to the findings in present study, heat stress causes an increase in reaction time and a decrease in selective attention. Thus, heat can be assumed as a stressor in hot work environments and the heat should be taken into account while design of job and tasks which needed selective attention or reaction time.

  2. Selective therapy in equine parasite control--application and limitations.

    Science.gov (United States)

    Nielsen, M K; Pfister, K; von Samson-Himmelstjerna, G

    2014-05-28

    Since the 1960s equine parasite control has relied heavily on frequent anthelmintic treatments often applied with frequent intervals year-round. However, increasing levels of anthelmintic resistance in cyathostomins and Parascaris equorum are now forcing the equine industry to change to a more surveillance-based treatment approach to facilitate a reduction in treatment intensity. The principle of selective therapy has been implemented with success in small ruminant parasite control, and has also found use in horse populations. Typically, egg counts are performed from all individuals in the population, and those exceeding a predetermined cutoff threshold are treated. Several studies document the applicability of this method in populations of adult horses, where the overall cyathostomin egg shedding can be controlled by only treating about half the horses. However, selective therapy has not been evaluated in foals and young horses, and it remains unknown whether the principle is adequate to also provide control over other important parasites such as tapeworms, ascarids, and large strongyles. One recent study associated selective therapy with increased occurrence of Strongylus vulgaris. Studies are needed to evaluate potential health risks associated with selective therapy, and to assess to which extent development of anthelmintic resistance can be delayed with this approach. The choice of strongyle egg count cutoff value for anthelmintic treatment is currently based more on tradition than science, and a recent publication illustrated that apparently healthy horses with egg counts below 100 eggs per gram (EPG) can harbor cyathostomin burdens in the range of 100,000 luminal worms. It remains unknown whether leaving such horses untreated constitutes a potential threat to equine health. The concept of selective therapy has merit for equine strongyle control, but several questions remain as it has not been fully scientifically evaluated. There is a great need for new and

  3. Selected specific rates of reactions of transients from water in aqueous solution. II. Hydrogen atom

    International Nuclear Information System (INIS)

    Anbar, M.; Farhataziz; Ross, A.B.

    1975-05-01

    Rates of reactions of hydrogen atoms (from radiolysis of water and other sources) with organic and inorganic molecules, ions, and transients in aqueous solution were tabulated. Directly measured rates obtained by kinetic spectroscopy or conductimetric methods, and relative rates determined by competition kinetics are included. (U.S.)

  4. Highly selective synthesis of (E)-alkenyl-(pentafluorosulfanyl)benzenes through Horner-Wadsworth-Emmons reaction

    Czech Academy of Sciences Publication Activity Database

    Iakobson, George; Beier, Petr

    2012-01-01

    Roč. 8, 25 Jul (2012), s. 1185-1190 ISSN 1860-5397 R&D Projects: GA ČR GAP207/12/0072 Institutional support: RVO:61388963 Keywords : Horner-Wadsworth-Emmons reaction * pentafluorosulfanyl group * phosphonates * sulfurpentafluoride Subject RIV: CC - Organic Chemistry Impact factor: 2.801, year: 2012

  5. Thermally activated reaction–diffusion-controlled chemical bulk reactions of gases and solids

    Directory of Open Access Journals (Sweden)

    S. Möller

    2015-01-01

    Full Text Available The chemical kinetics of the reaction of thin films with reactive gases is investigated. The removal of thin films using thermally activated solid–gas to gas reactions is a method to in-situ control deposition inventory in vacuum and plasma vessels. Significant scatter of experimental deposit removal rates at apparently similar conditions was observed in the past, highlighting the need for understanding the underlying processes. A model based on the presence of reactive gas in the films bulk and chemical kinetics is presented. The model describes the diffusion of reactive gas into the film and its chemical interaction with film constituents in the bulk using a stationary reaction–diffusion equation. This yields the reactive gas concentration and reaction rates. Diffusion and reaction rate limitations are depicted in parameter studies. Comparison with literature data on tokamak co-deposit removal results in good agreement of removal rates as a function of pressure, film thickness and temperature.

  6. Design of an Adaptive-Neural Network Attitude Controller of a Satellite using Reaction Wheels

    Directory of Open Access Journals (Sweden)

    Abbas Ajorkar

    2015-04-01

    Full Text Available In this paper, an adaptive attitude control algorithm is developed based on neural network for a satellite using four reaction wheels in a tetrahedron configuration. Then, an attitude control based on feedback linearization control has been designed and uncertainties in the moment of inertia matrix and disturbances torque have been considered. In order to eliminate the effect of these uncertainties, a multilayer neural network with back-propagation law is designed. In this structure, the parameters of the moment of inertia matrix and external disturbances are estimated and used in feedback linearization control law. Finally, the performance of the designed attitude controller is investigated by several simulations.

  7. Molecular nucleation mechanisms and control strategies for crystal polymorph selection

    Science.gov (United States)

    van Driessche, Alexander E. S.; van Gerven, Nani; Bomans, Paul H. H.; Joosten, Rick R. M.; Friedrich, Heiner; Gil-Carton, David; Sommerdijk, Nico A. J. M.; Sleutel, Mike

    2018-04-01

    The formation of condensed (compacted) protein phases is associated with a wide range of human disorders, such as eye cataracts, amyotrophic lateral sclerosis, sickle cell anaemia and Alzheimer’s disease. However, condensed protein phases have their uses: as crystals, they are harnessed by structural biologists to elucidate protein structures, or are used as delivery vehicles for pharmaceutical applications. The physiochemical properties of crystals can vary substantially between different forms or structures (‘polymorphs’) of the same macromolecule, and dictate their usability in a scientific or industrial context. To gain control over an emerging polymorph, one needs a molecular-level understanding of the pathways that lead to the various macroscopic states and of the mechanisms that govern pathway selection. However, it is still not clear how the embryonic seeds of a macromolecular phase are formed, or how these nuclei affect polymorph selection. Here we use time-resolved cryo-transmission electron microscopy to image the nucleation of crystals of the protein glucose isomerase, and to uncover at molecular resolution the nucleation pathways that lead to two crystalline states and one gelled state. We show that polymorph selection takes place at the earliest stages of structure formation and is based on specific building blocks for each space group. Moreover, we demonstrate control over the system by selectively forming desired polymorphs through site-directed mutagenesis, specifically tuning intermolecular bonding or gel seeding. Our results differ from the present picture of protein nucleation, in that we do not identify a metastable dense liquid as the precursor to the crystalline state. Rather, we observe nucleation events that are driven by oriented attachments between subcritical clusters that already exhibit a degree of crystallinity. These insights suggest ways of controlling macromolecular phase transitions, aiding the development of protein

  8. Genetic control of the angular leaf spot reaction in common bean leaves and pods

    Directory of Open Access Journals (Sweden)

    Jerônimo Constantino Borel

    2011-12-01

    Full Text Available Information about genetic control of plant reaction to pathogens is essential in plant breeding programs focusing resistance. This study aimed to obtain information about genetic control of the angular leaf spot reaction in leaves and pods from common bean (Phaseolus vulgaris L. line ESAL 686. This line was crossed with cultivars Jalo EEP 558 (resistant, Cornell 49-242 (resistant and Carioca MG (susceptible. Generations F1, F2 and backcrosses (BC11 and BC21 were obtained. In the dry season (2009, parents and respective populations were evaluated for angular leaf spot reaction under field conditions. Disease severity was evaluated on leaves and pods using diagrammatic scales. Severity scores were obtained and mean and variance genetic components were estimated for both. Segregation of F2 generation was analyzed for some crosses. Different genes control angular leaf spot reaction in leaves and pods. Mean and variance components showed predominance of additive effects. Heritability was high, however, was greater on pods than on leaves which indicated that leaf reaction is more influenced by the environment.

  9. The Maillard reaction and its control during food processing. The potential of emerging technologies.

    Science.gov (United States)

    Jaeger, H; Janositz, A; Knorr, D

    2010-06-01

    The Maillard reaction between reducing sugars and amino acids is a common reaction in foods which undergo thermal processing. Desired consequences like the formation of flavor and brown color of some cooked foods but also the destruction of essential amino acids and the production of anti-nutritive compounds require the consideration of the Maillard reaction and relevant mechanisms for its control. This paper aims to exemplify the recent advances in food processing with regard to the controllability of heat-induced changes in the food quality. Firstly, improved thermal technologies, such as ohmic heating, which allows direct heating of the product and overcoming the heat transfer limitations of conventional thermal processing are presented in terms of their applicability to reduce the thermal exposure during food preservation. Secondly, non-thermal technologies such as high hydrostatic pressure and pulsed electric fields and their ability to extend the shelf life of food products without the application of heat, thus also preserving the quality attributes of the food, will be discussed. Finally, an innovative method for the removal of Maillard reaction substrates in food raw materials by the application of pulsed electric field cell disintegration and extraction as well as enzymatic conversion is presented in order to demonstrate the potential of the combination of processes to control the occurrence of the Maillard reaction in food processing. (c) 2009 Elsevier Masson SAS. All rights reserved.

  10. Influences of the molecular fuel structure on combustion reactions towards soot precursors in selected alkane and alkene flames.

    Science.gov (United States)

    Ruwe, Lena; Moshammer, Kai; Hansen, Nils; Kohse-Höinghaus, Katharina

    2018-04-25

    In this study, we experimentally investigate the high-temperature oxidation kinetics of n-pentane, 1-pentene and 2-methyl-2-butene (2M2B) in a combustion environment using flame-sampling molecular beam mass spectrometry. The selected C5 fuels are prototypes for linear and branched, saturated and unsaturated fuel components, featuring different C-C and C-H bond structures. It is shown that the formation tendency of species, such as polycyclic aromatic hydrocarbons (PAHs), yielded through mass growth reactions increases drastically in the sequence n-pentane fuel-dependent reaction sequences of the gas-phase combustion mechanism that provide explanations for the observed difference in the PAH formation tendency. First, we investigate the fuel-structure-dependent formation of small hydrocarbon species that are yielded as intermediate species during the fuel decomposition, because these species are at the origin of the subsequent mass growth reaction pathways. Second, we review typical PAH formation reactions inspecting repetitive growth sequences in dependence of the molecular fuel structure. Third, we discuss how differences in the intermediate species pool influence the formation reactions of key aromatic ring species that are important for the PAH growth process underlying soot formation. As a main result it was found that for the fuels featuring a C[double bond, length as m-dash]C double bond, the chemistry of their allylic fuel radicals and their decomposition products strongly influences the combination reactions to the initially formed aromatic ring species and as a consequence, the PAH formation tendency.

  11. Origin of Exo/Endo Selectivity in the Intramolecular Diels-Alder Reaction

    International Nuclear Information System (INIS)

    Yan, Shihai; Ryu, Do Hyun; Lee, Jin Yong

    2010-01-01

    The stereoselectivity of the intramolecular Diels-Alder reactions of 1 and its derivatives were investigated by ab initio calculations. The stereoselectivity mainly originates from the steric repulsion and the orbital interactions. The additional s-cis and s-trans conformations by introducing the carbonyl group at the neighbor of diene or dienophile may change the stereoselectivity, hence this kind of substitution can be utilized for stereoselective asymmetric synthesis

  12. Photochemical exchange reactions of thymine, uracil and their nucleosides with selected amino acids

    International Nuclear Information System (INIS)

    Shetlar, M.D.; Taylor, J.A.; Hom, K.

    1984-01-01

    The photoinduced exchange reactions of thymine with lysine at basic pH, using 254 nm light, have been studied. Three products have been isolated, namely, 6-amino-2-(1-thyminyl)hexanoic acid (Ia), 2-amino-6-(1-thyminyl)hexanoic acid (IIa) and 1-amino-5-(1-thyminyl)pentane (IIIa). Compound IIIa was shown to be a secondary product, produced by photochemical decarboxylation of Ia. Photochemical reaction of thymine with glycine and alanine at basic pH led, respectively, to formation of 2-(1-thyminyl)acetic acid (Ic) and 2-(1-thyminyl)propionic acid (Id). Compounds Ic and Id underwent photolysis to produce the decarboxylated secondary products 1-methylthymine and 1-ethylthymine, respectively. Thymidine reacts photochemically with glycine and alanine to produce the same products. Irradiation of DNA in the presence of lysine at basic pH led to the formation of the same products formed in the thymine-lysine system, namely Ia, IIa and IIIa. Uracil was found to undergo analogous photochemical exchange reactions with lysine to form 6-amino-2-(1-uracilyl)hexanoic acid (Ib), and 2-amino-6-(1-uracilyl)hexanoic acid (IIb). Compound Ib was found to undergo photodecarboxylation to form 1-amino-5-(1-uracilyl)pentane (IIIb), analogous to the secondary photoreaction of Ia. Photoreaction of uracil with 1,5-diaminopentane (cadaverine) likewise led to formation of IIIb. (author)

  13. Selected phytotoxins and organic extracts from endophytic fungus Edenia gomezpompae as light reaction of photosynthesis inhibitors.

    Science.gov (United States)

    Macías-Rubalcava, Martha Lydia; Ruiz-Velasco Sobrino, María Emma; Meléndez-González, Claudio; King-Díaz, Beatriz; Lotina-Hennsen, Blas

    2014-09-05

    In a search for natural herbicides, we investigated the action mechanism of the naphthoquinone spiroketals, isolated from the endophytic fungus Edenia gomezpompae: preussomerins EG1 (1) and EG4 (2), and palmarumycins CP17 (3), and CP2 (4) on the photosynthesis light reactions. The naphthoquinone spiroketals 1-4 inhibited the ATP synthesis in freshly lysed spinach thylakoids from water to MV, and they also inhibited the non-cyclic electron transport in the basal, phosphorylating and uncoupled conditions from water to MV. Therefore, they act as Hill reaction inhibitors. The results suggested that naphthoquinone spiroketals 1-4 have two interactions and inhibition site on the PSII electron transport chain. The first one involves the water splitting enzyme inhibition; and, the second on the acceptor site of PSII in a similar way that herbicide Diuron, studied by polaroghaphy and corroborated by fluorescence of the chlorophyll a of PSII. The culture medium and mycelium organic extracts from four morphological variants of E. gomezpompae were phytotoxic, and the culture medium extracts were more potent than mycelium extracts. They also act as Hill reaction inhibitors. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Applicant Reactions to Selection Events : Four studies into the role of attributional style and fairness perceptions

    NARCIS (Netherlands)

    Schinkel, S.; van Vianen, A.E.M.; Ryan, A.M.

    2016-01-01

    In four studies, applicants’ (N = 478) organizational attractiveness perceptions and recommendation intentions following selection outcomes were measured. In three field studies, actual applicants’ perceptions were measured in authentic, high-stakes application contexts, both preprocedure and

  15. Bayesian selective response-adaptive design using the historical control.

    Science.gov (United States)

    Kim, Mi-Ok; Harun, Nusrat; Liu, Chunyan; Khoury, Jane C; Broderick, Joseph P

    2018-06-13

    High quality historical control data, if incorporated, may reduce sample size, trial cost, and duration. A too optimistic use of the data, however, may result in bias under prior-data conflict. Motivated by well-publicized two-arm comparative trials in stroke, we propose a Bayesian design that both adaptively incorporates historical control data and selectively adapt the treatment allocation ratios within an ongoing trial responsively to the relative treatment effects. The proposed design differs from existing designs that borrow from historical controls. As opposed to reducing the number of subjects assigned to the control arm blindly, this design does so adaptively to the relative treatment effects only if evaluation of cumulated current trial data combined with the historical control suggests the superiority of the intervention arm. We used the effective historical sample size approach to quantify borrowed information on the control arm and modified the treatment allocation rules of the doubly adaptive biased coin design to incorporate the quantity. The modified allocation rules were then implemented under the Bayesian framework with commensurate priors addressing prior-data conflict. Trials were also more frequently concluded earlier in line with the underlying truth, reducing trial cost, and duration and yielded parameter estimates with smaller standard errors. © 2018 The Authors. Statistics in Medicine Published by John Wiley & Sons, Ltd.

  16. Dependence and withdrawal reactions to benzodiazepines and selective serotonin reuptake inhibitors. How did the health authorities react?

    Science.gov (United States)

    Nielsen, Margrethe; Hansen, Ebba Holme; Gøtzsche, Peter C

    2013-01-01

    Our objective was to explore communications from drug agencies about benzodiazepine dependence and selective serotonin reuptake inhibitors (SSRIs) withdrawal reactions over time. Documentary study. We searched the web-sites of the European Medicines Agency and the drug agencies in USA, UK, and Denmark for documents mentioning benzodiazepines or SSRIs. We supplemented with other relevant literature that could contribute to our study. The searches were performed in 2009 in PubMed, Google, BMJ and JAMA. It took many years before the drug regulators acknowledged benzodiazepine dependence and SSRI withdrawal reactions and before the prescribers and the public were informed. Drug regulators relied mainly on the definitions of dependence and withdrawal reactions from the diagnostic psychiatric manuals, which contributed to the idea that SSRIs do not cause dependence, although it is difficult for many patients to stop treatment. In the perspective of a precautionary principle, drug agencies have failed to acknowledge that SSRIs can cause dependence and have minimised the problem with regard to its frequency and severity. In the perspective of a risk management principle, the drug agencies have reacted in concordance with the slowly growing knowledge of adverse drug reactions and have sharpened the information to the prescribers and the public over time. However, solely relying on spontaneous reporting of adverse effects leads to underestimation and delayed information about the problems. Given the experience with the benzodiazepines, we believe the regulatory bodies should have required studies from the manufacturers that could have elucidated the dependence potential of the SSRIs before marketing authorization was granted.

  17. Optically Controlled Electron-Transfer Reaction Kinetics and Solvation Dynamics : Effect of Franck-Condon States

    NARCIS (Netherlands)

    Gupta, Kriti; Patra, Aniket; Dhole, Kajal; Samanta, Alok Kumar; Ghosh, Swapan K.

    2017-01-01

    Experimental results for optically controlled electron-transfer reaction kinetics (ETRK) and nonequilibrium solvation dynamics (NESD) of Coumarin 480 in DMPC vesicle show their dependence on excitation wavelength λex. However, the celebrated Marcus theory and linear-response-theory-based approaches

  18. An insect with selective control of egg coloration.

    Science.gov (United States)

    Abram, Paul K; Guerra-Grenier, Eric; Després-Einspenner, Marie-Lyne; Ito, Shosuke; Wakamatsu, Kazumasa; Boivin, Guy; Brodeur, Jacques

    2015-08-03

    The color and patterning of animal eggs has important consequences for offspring survival. There are examples of between-species and polymorphic differences in egg coloration in birds and amphibians [1-3], as well as cases of birds and insects whose nutritional status or age can cause within-individual variation in egg pigmentation [4-6]. However, no studies to date have demonstrated that individual animals can selectively control the color of their eggs. Here, we show that individual females of the predatory stink bug Podisus maculiventris can control the pigmentation of their eggs during oviposition, as a response to environmental conditions. The color of egg masses produced by individual females can range from pale yellow to dark black/brown. Females tend to lay darker eggs, which are more resistant to UV radiation, on the upper surface of leaves where UV exposure is highest in nature. Conversely, they lay lighter eggs on the undersides of leaves. However, egg color is not determined by the intensity of UV radiation falling on the surface where they are laid. Rather, female stink bugs appear to use a visual assessment of oviposition substrate reflectance to determine egg color. Unexpectedly, biochemical analyses revealed that the egg pigment is not melanin, the most ubiquitous light-absorbing pigment in animals. Our study offers the first example of an animal able to selectively control the color of its eggs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Selection of anthracnose resistant common beans using detached leaves in partially controlled environment

    Directory of Open Access Journals (Sweden)

    Alisson Campos Pereira

    2014-08-01

    Full Text Available The objectives of this study were to evaluate the possibility of selecting anthracnose resistant common bean plants using detached primary leaves in partially controlled environment of a greenhouse and identify differences in the reaction of genotypes to anthracnose. The common bean cultivars Ouro Negro, OuroVermelho, ManteigãoFosco 11, Rudá, Rudá-R, VP8, BRSMG Madrepérola, Pérola, MeiaNoite and BRSMG Talismãwere characterizedfor resistance to the races 65, 81 and 453 of Colletotrichum lindemuthianum and the method of detached primary leaves was compared to the method with the traditional inoculation of plants at the phenological stage V2. The lines Rudá, Rudá-R and Pérola were inoculated with the races 65 and 453 of C. lindemuthianum, aiming to assess the rate of coincidence of anthracnose severity by both inoculation methods. In general, the two methods presented similar results for the reaction of the cultivars. The use of detached primary leaves of common bean plants in the partially controlled environment was feasible for selection of plants resistant to anthracnose and has the advantages of low-needed infrastructure and reduction of resources, space and time.

  20. Multichannel Selective Femtosecond Coherent Control Based on Symmetry Properties

    International Nuclear Information System (INIS)

    Amitay, Zohar; Gandman, Andrey; Chuntonov, Lev; Rybak, Leonid

    2008-01-01

    We present and implement a new scheme for extended multichannel selective femtosecond coherent control based on symmetry properties of the excitation channels. Here, an atomic nonresonant two-photon absorption channel is coherently incorporated in a resonance-mediated (2+1) three-photon absorption channel. By proper pulse shaping, utilizing the invariance of the two-photon absorption to specific phase transformations of the pulse, the three-photon absorption is tuned independently over an order-of-magnitude yield range for any possible two-photon absorption yield. Noticeable is a set of ''two-photon dark pulses'' inducing widely tunable three-photon absorption

  1. Status of selected air pollution control programs, February 1992

    International Nuclear Information System (INIS)

    1992-02-01

    The collection of status reports has been prepared in order to provide a timely summary of selected EPA air pollution control activities to those individuals who are involved with the implementation of these programs. The report contains ozone/carbon monoxide (CO) programs; mobile sources programs; particulate matter nominally 10M and less (PM-10), sulfur dioxide (SO2) and lead programs; New Source Review (NSR); economics programs; emission standards programs; Indian activity programs; mobile sources programs; air toxics programs; acid rain programs; permits programs; chlorofluorocarbons programs; enforcement programs; and other programs

  2. Configuration Selection for Reconfigurable Control of Piecewise Affine Systems

    DEFF Research Database (Denmark)

    Tabatabaeipour, Mojtaba; Gholami, M.; Bak, T.

    2015-01-01

    the recongurability of the system and the optimal conguration in the architecture design phase. A recongurable control must ensure stability of the recongured system and, if possible, a graceful degradation in the performance. Therefore, in the proposed recongurability analysis, we consider both stabilizability......In this paper, the problem of conguration selection i.e. sensor/actuator placement for piecewise ane (PWA) systems subject to both sensor and actuator faults is considered. A method is proposed that provides a tool for the design phase to decide about the optimal placement of sensor/actuators where...... and performance of the system. The efficiency of the proposed method is demonstrated on several numerical examples...

  3. Selection of material balance areas and item control areas

    International Nuclear Information System (INIS)

    1975-04-01

    Section 70.58, ''Fundamental Nuclear Material Controls,'' of 10 CFR Part 70, ''Special Nuclear Material,'' requires certain licensees authorized to possess more than one effective kilogram of special nuclear material to establish Material Balance Areas (MBAs) or Item Control Areas (ICAs) for the physical and administrative control of nuclear materials. This section requires that: (1) each MBA be an identifiable physical area such that the quantity of nuclear material being moved into or out of the MBA is represented by a measured value; (2) the number of MBAs be sufficient to localize nuclear material losses or thefts and identify the mechanisms; (3) the custody of all nuclear material within an MBA or ICA be the responsibility of a single designated individual; and (4) ICAs be established according to the same criteria as MBAs except that control into and out of such areas would be by item identity and count for previously determined special nuclear material quantities, the validity of which must be ensured by tamper-safing unless the items are sealed sources. This guide describes bases acceptable to the NRC staff for the selection of material balance areas and item control areas. (U.S.)

  4. A novel approach to sports concussion assessment: Computerized multilimb reaction times and balance control testing.

    Science.gov (United States)

    Vartiainen, Matti V; Holm, Anu; Lukander, Jani; Lukander, Kristian; Koskinen, Sanna; Bornstein, Robert; Hokkanen, Laura

    2016-01-01

    Mild traumatic brain injuries (MTBI) or concussions often result in problems with attention, executive functions, and motor control. For better identification of these diverse problems, novel approaches integrating tests of cognitive and motor functioning are needed. The aim was to characterize minor changes in motor and cognitive performance after sports-related concussions with a novel test battery, including balance tests and a computerized multilimb reaction time test. The cognitive demands of the battery gradually increase from a simple stimulus response to a complex task requiring executive attention. A total of 113 male ice hockey players (mean age = 24.6 years, SD = 5.7) were assessed before a season. During the season, nine concussed players were retested within 36 hours, four to six days after the concussion, and after the season. A control group of seven nonconcussed players from the same pool of players with comparable demographics were retested after the season. Performance was measured using a balance test and the Motor Cognitive Test battery (MotCoTe) with multilimb responses in simple reaction, choice reaction, inhibition, and conflict resolution conditions. The performance of the concussed group declined at the postconcussion assessment compared to both the baseline measurement and the nonconcussed controls. Significant changes were observed in the concussed group for the multilimb choice reaction and inhibition tests. Tapping and balance showed a similar trend, but no statistically significant difference in performance. In sports-related concussions, complex motor tests can be valuable additions in assessing the outcome and recovery. In the current study, using subtasks with varying cognitive demands, it was shown that while simple motor performance was largely unaffected, the more complex tasks induced impaired reaction times for the concussed subjects. The increased reaction times may reflect the disruption of complex and integrative cognitive

  5. Chemistry and kinetics of size-selected cobalt cluster cations at thermal energies. I. Reactions with CO

    Science.gov (United States)

    Guo, B. C.; Kerns, K. P.; Castleman, A. W., Jr.

    1992-06-01

    The chemistry and kinetics of size-selected Co+n cluster-ion (n=2-8) reactions with CO are studied using a selected ion drift tube affixed with a laser vaporization source operated under well-defined thermal conditions. All reactions studied in the present work are found to be association reactions. Their absolute rate constants, which are determined quantitatively, are found to have a strong dependence on cluster size. Similar to the cases of reactions with many other reactants such as H2 and CH4, Co+4 and Co+5 display a higher reactivity toward the CO molecule than do clusters of neighboring size. The multiple-collision conditions employed in the present work have enabled a determination of the maximum coordination number of CO molecules bound onto each Co+n cluster. It is found that the tetramer tends to bond 12 CO molecules, the pentamer 14 CO, hexamer 16 CO, and so on. The results are interpreted in terms of Lauher's calculation and the polyhedral skeletal electron pair theory. All the measured maximum coordination numbers correlate extremely well with the predictions of these theories, except for the trimer where the measured number is one CO less than the predicted value. The good agreement between experiment and theory enables one to gain some insight into the geometric structure of the clusters. Based on the present findings, the cobalt tetramer cation is interpreted to have a tetrahedral structure, the pentamer a trigonal bipyramid, and the hexamer an octahedral structure. Other cluster structures are also discussed.

  6. Uranium solubility and solubility controls in selected Needle's Eye groundwaters

    International Nuclear Information System (INIS)

    Falck, W.E.; Hooker, P.J.

    1991-01-01

    The solubility control of uranium in selected groundwater samples from the cliff and sediments at the Needle's Eye natural analogue site is investigated using the speciation code PHREEQE and the CHEMVAL thermodynamic database (release 3). Alkali-earth bearing uranyl carbonate secondary minerals are likely to exert influence on the solubility . Other candidates are UO 2 and arsenates, depending on the prevailing redox conditions. In the absence of literature data, solubility products for important arsenates have been estimated from analogy with other arsenates and phosphates. Phosphates themselves are unlikely to exert control owing to their comparatively high solubilities. The influence of seawater flooding into the sediments is also discussed. The importance of uranyl arsenates in the retardation of uranium in shallow sediments has been demonstrated in theory, but there are some significant gaps in the thermodynamic databases used. (author)

  7. Size-selective electrocatalytic activity of (Pt)n/MoS2for oxygen reduction reaction

    DEFF Research Database (Denmark)

    Bothra, Pallavi; Pandey, Mohnish; Pati, Swapan K.

    2016-01-01

    In the present work, we have investigated the electrocatalytic activity of the oxygen reduction reaction (ORR), O2 + 4H+ + 4e− → 2H2O, for (Pt)n clusters (n = 1, 2, 3, 5, 7, 10 and 12) adsorbed on semiconducting (2H) and metallic (1T) MoS2 monolayers using first principles density functional theory....... We have considered four elementary reactions involved in ORR within a unified electrochemical thermodynamic framework and the corresponding Gibbs adsorption free energies of the key intermediates (*OOH, *O, *OH) associated with each step have been calculated. The results indicate that the reduction...... of adsorbed hydroxyl (*OH) to water (*OH + H+ + e− → H2O) is the bottleneck step in the ORR process. The adsorption free energy of *OH (ΔG*OH) is found to be the thermodynamic descriptor for the present systems. Eventually, the ORR activity has been described as a function of ΔG*OH and a volcano plot...

  8. On the effect of tether composition on cis/trans selectivity in intramolecular Diels-Alder reactions.

    Science.gov (United States)

    Paddon-Row, Michael N; Longshaw, Alistair I; Willis, Anthony C; Sherburn, Michael S

    2009-01-05

    Intramolecular Diels-Alder (IMDA) transition structures (TSs) and energies have been computed at the B3LYP/6-31+G(d) and CBS-QB3 levels of theory for a series of 1,3,8-nonatrienes, H(2)C=CH-CH=CH-CH(2)-X-Z-CH=CH(2) [-X-Z- = -CH(2)-CH(2)- (1); -O-C(=O)- (2); -CH(2)-C(=O)- (3); -O-CH(2)- (4); -NH-C(=O)- (5); -S-C(=O)- (6); -O-C(=S)- (7); -NH-C(=S)- (8); -S-C(=S)- (9)]. For each system studied (1-9), cis- and trans-TS isomers, corresponding, respectively, to endo- and exo-positioning of the -C-X-Z- tether with respect to the diene, have been located and their relative energies (E(rel) (TS)) employed to predict the cis/trans IMDA product ratio. Although the E(rel) (TS) values are modest (typically NH or S), the IMDA cis stereoselectivity diminishes. The predicted stereochemical reaction preferences are explained in terms of two opposing effects operating in the cis-TS, namely (1) unfavorable torsional (eclipsing) strain about the C4-C5 bond, that is caused by the -C-X-C(=Y)- group's strong tendency to maintain local planarity; and (2) attractive electrostatic and secondary orbital interactions between the endo-(thio)carbonyl group, C=Y, and the diene. The former interaction predominates when X is weakly electronegative (X=N, S), while the latter is dominant when X is more strongly electronegative (X=O), or a methylene group (X=CH(2)) which increases tether flexibility. These predictions hold up to experimental scrutiny, with synthetic IMDA reactions of 1, 2, 3, and 4 (published work) and 5, 6, and 8 (this work) delivering ratios close to those calculated. The reactions of thiolacrylate 5 and thioamide 8 represent the first examples of IMDA reactions with tethers of these types. Our results point to strategies for designing tethers, which lead to improved cis/trans-selectivities in IMDAs that are normally only weakly selective. Experimental verification of the validity of this claim comes in the form of fumaramide 14, which undergoes a more trans-selective IMDA reaction

  9. Quantitative and Selective Analysis of Feline Growth Related Proteins Using Parallel Reaction Monitoring High Resolution Mass Spectrometry.

    Directory of Open Access Journals (Sweden)

    Mårten Sundberg

    Full Text Available Today immunoassays are widely used in veterinary medicine, but lack of species specific assays often necessitates the use of assays developed for human applications. Mass spectrometry (MS is an attractive alternative due to high specificity and versatility, allowing for species-independent analysis. Targeted MS-based quantification methods are valuable complements to large scale shotgun analysis. A method referred to as parallel reaction monitoring (PRM, implemented on Orbitrap MS, has lately been presented as an excellent alternative to more traditional selected reaction monitoring/multiple reaction monitoring (SRM/MRM methods. The insulin-like growth factor (IGF-system is not well described in the cat but there are indications of important differences between cats and humans. In feline medicine IGF-I is mainly analyzed for diagnosis of growth hormone disorders but also for research, while the other proteins in the IGF-system are not routinely analyzed within clinical practice. Here, a PRM method for quantification of IGF-I, IGF-II, IGF binding protein (BP -3 and IGFBP-5 in feline serum is presented. Selective quantification was supported by the use of a newly launched internal standard named QPrEST™. Homology searches demonstrated the possibility to use this standard of human origin for quantification of the targeted feline proteins. Excellent quantitative sensitivity at the attomol/μL (pM level and selectivity were obtained. As the presented approach is very generic we show that high resolution mass spectrometry in combination with PRM and QPrEST™ internal standards is a versatile tool for protein quantitation across multispecies.

  10. Site-selective three-component reaction for dual-functionalization of peptides

    DEFF Research Database (Denmark)

    Munch, Henrik Kofoed; Rasmussen, Jakob Ewald; Popa, Gina

    2013-01-01

    A site-selective dual-functionalization of peptides is presented, involving readily available maleimides as well as N-hydroxylamines. The modification proceeds through a three component 1,3-dipolar cycloaddition, forming a stable product. This was exemplified by the one-pot attachment of two...

  11. Neural Network Control of CSTR for Reversible Reaction Using Reverence Model Approach

    Directory of Open Access Journals (Sweden)

    Duncan ALOKO

    2007-01-01

    Full Text Available In this work, non-linear control of CSTR for reversible reaction is carried out using Neural Network as design tool. The Model Reverence approach in used to design ANN controller. The idea is to have a control system that will be able to achieve improvement in the level of conversion and to be able to track set point change and reject load disturbance. We use PID control scheme as benchmark to study the performance of the controller. The comparison shows that ANN controller out perform PID in the extreme range of non-linearity.This paper represents a preliminary effort to design a simplified neutral network control scheme for a class of non-linear process. Future works will involve further investigation of the effectiveness of thin approach for the real industrial chemical process

  12. Computational intelligence-based polymerase chain reaction primer selection based on a novel teaching-learning-based optimisation.

    Science.gov (United States)

    Cheng, Yu-Huei

    2014-12-01

    Specific primers play an important role in polymerase chain reaction (PCR) experiments, and therefore it is essential to find specific primers of outstanding quality. Unfortunately, many PCR constraints must be simultaneously inspected which makes specific primer selection difficult and time-consuming. This paper introduces a novel computational intelligence-based method, Teaching-Learning-Based Optimisation, to select the specific and feasible primers. The specified PCR product lengths of 150-300 bp and 500-800 bp with three melting temperature formulae of Wallace's formula, Bolton and McCarthy's formula and SantaLucia's formula were performed. The authors calculate optimal frequency to estimate the quality of primer selection based on a total of 500 runs for 50 random nucleotide sequences of 'Homo species' retrieved from the National Center for Biotechnology Information. The method was then fairly compared with the genetic algorithm (GA) and memetic algorithm (MA) for primer selection in the literature. The results show that the method easily found suitable primers corresponding with the setting primer constraints and had preferable performance than the GA and the MA. Furthermore, the method was also compared with the common method Primer3 according to their method type, primers presentation, parameters setting, speed and memory usage. In conclusion, it is an interesting primer selection method and a valuable tool for automatic high-throughput analysis. In the future, the usage of the primers in the wet lab needs to be validated carefully to increase the reliability of the method.

  13. Waterhammer modeling for the Ares I Upper Stage Reaction Control System cold flow development test article

    Science.gov (United States)

    Williams, Jonathan Hunter

    The Upper Stage Reaction Control System provides in-flight three-axis attitude control for the Ares I Upper Stage. The system design must accommodate rapid thruster firing to maintain proper launch trajectory and thus allow for the possibility to pulse multiple thrusters simultaneously. Rapid thruster valve closure creates an increase in static pressure, known as waterhammer, which propagates throughout the propellant system at pressures exceeding nominal design values. A series of development tests conducted at Marshall Space Flight Center in 2009 were performed using a water-flow test article to better understand fluid characteristics of the Upper Stage Reaction Control System. A subset of the tests examined the waterhammer pressure and frequency response in the flight-representative system and provided data to anchor numerical models. This thesis presents a comparison of waterhammer test results with numerical model and analytical results. An overview of the flight system, test article, modeling and analysis are also provided.

  14. Production control and supplier selection under demand disruptions

    Directory of Open Access Journals (Sweden)

    Xianzhe Chen

    2010-12-01

    Full Text Available This paper investigates the effects of demand disruptions on production control and supplier selection in a three-echelon supply chain system. The customer demand is modeled as a jump-diffusion process in a continuous-time setting. A two-number production-inventory policy is implemented in the production control model for the manufacturer. The objective is to minimize the long-term average total cost consisting of backlog cost, holding cost, switching cost, and ordering cost. The simulated annealing method is applied to search the optimal critical switching values. Furthermore, an improved analytical hierarchy process (AHP is proposed to select the best supplier, based on quantitative factors such as the optimal long-term total cost obtained through the simulated annealing method under demand disruptions and qualitative factors such as quality and service. Numerical studies are conducted to demonstrate the effects of demand disruptions in the face of various risk scenarios. Managerial insights from simulation results are provided as well. Our approaches can be implemented as the “stress test” for companies in front of various supply chain disruption scenarios.

  15. Selected parameters of moulding sands for designing quality control systems

    Directory of Open Access Journals (Sweden)

    J. Jakubski

    2010-07-01

    Full Text Available One of the modern methods of production optimisation are artificial neural networks. Neural networks owe their popularity to the fact thatthey are convenient tools, which can be utilised in a wide scope of problems. They are capable of reflecting complex functions. Especiallytheir non-linearity should be emphasised. They are gaining wider and wider application in the foundry industry, among others, to controlmelting processes in cupolas and arc furnaces, designing castings and supply systems, control of moulding sands treatments, prediction ofproperties of cast alloys as well as selecting die casting.An attempt of the application neural networks to the quality control of moulding sands with bentonite is presented in the paper. This isa method of assessing the suitability of moulding sands by finding correlations in between individual parameters, by means of artificialneural network systems. The presented investigations were performed with the application of the Statistica 8.0 program.The investigations were aimed at the selection of the proper kind of a neural network for prediction a sand moistness on the bases ofcertain moulding sand properties such as: permeability, compactibility and friability. These parameters – determined as sand moistness functions - were introduced as initial parameters.Application of the Statistica program allowed for an automatic selection of the most suitable network for the reflection of dependencies and interactions existing among the proposed parameters. The best results were obtained for unidirectional multi-layer perception network (MLP. The neural network sensitivity to individual moulding sand parameters was determined, which allowed to reject not important parameters when constructing the network.

  16. Mass transfer rate through liquid membranes: interfacial chemical reactions and diffusion as simultaneous permeability controlling factors

    International Nuclear Information System (INIS)

    Danesi, P.R.; Horwitz, E.P.; Vandegrift, G.F.; Chiarizia, R.

    1981-01-01

    Equations describing the permeability of a liquid membrane to metal cations have been derived taking into account aqueous diffusion, membrane diffusion, and interfacial chemical reactions as simultaneous permeability controlling factors. Diffusion and chemical reactions have been coupled by a simple model analogous to the one previously described by us to represent liquid-liquid extraction kinetics. The derived equations, which make use of experimentally determined interfacial reaction mechanisms, qualitatively fit unexplained literature data regarding Cu 2+ transfer through liquid membranes. Their use to predict and optimize membrane permeability in practical separation processes by setting the appropriate concentration of the membrane carrier [LIX 64 (General Mills), a commercial β-hydroxy-oxime] and the pH of the aqueous copper feed solution is briefly discussed. 4 figures

  17. Competing reactions of selected atmospheric gases on Fe3O4 nanoparticles surfaces.

    Science.gov (United States)

    Eltouny, N; Ariya, Parisa A

    2014-11-14

    Heterogeneous reactions on atmospheric aerosol surfaces are increasingly considered important in understanding aerosol-cloud nucleation and climate change. To understand potential reactions in polluted atmospheres, the co-adsorption of NO2 and toluene to magnetite (Fe3O4i.e. FeO·Fe2O3) nanoparticles at ambient conditions was investigated for the first time. The surface area, size distribution, and morphology of Fe3O4 nanoparticles were characterized by BET method and high-resolution transmission electron microscopy. Adsorption isotherms, collected by gas chromatography with flame ionization detection, showed that the presence of NO2 decreased the adsorption of toluene. The analyses of the surface chemical composition of Fe3O4 by X-ray photoelectron spectroscopy (XPS) reveal that, upon the addition of NO2, the surface is oxidized and a contribution at 532.5 ± 0.4 eV in the O1s spectrum appears, showing that NO2 likely competes with toluene by dissociating on Fe(2+) sites and forming NO3(-). Different competing effects were observed for oxidized Fe3O4; oxidation occurred when exposed solely to NO2, whereas, the mixture of toluene and NO2 resulted in a reduction of the surface i.e. increased Fe(2+)/Fe(3+). Analyses by time of flight secondary ion mass spectrometry further suggest toluene reacts with Fe(3+) sites forming oxygenated organics. Our results indicate that on reduced magnetite, NO2 is more reactive and competes with toluene; in contrast, on oxidized Fe3O4, toluene is more reactive. Because magnetite can assume a range of oxidation ratios in the environment, different competing interactions between pollutants like NO2 and toluene could influence atmospheric processes, namely, the formation of Fe(2+) and the formation of atmospheric oxidants.

  18. A Selected Reaction Monitoring Mass Spectrometry Protocol for Validation of Proteomic Biomarker Candidates in Studies of Psychiatric Disorders.

    Science.gov (United States)

    Reis-de-Oliveira, Guilherme; Garcia, Sheila; Guest, Paul C; Cassoli, Juliana S; Martins-de-Souza, Daniel

    2017-01-01

    Most biomarker candidates arising from proteomic studies of psychiatric disorders have not progressed for use in clinical studies due to insufficient validation steps. Here we describe a selective reaction monitoring mass spectrometry (SRM-MS) approach that could be used as a follow-up validation tool of proteins identified in blood serum or plasma. This protocol specifically covers the stages of peptide selection and optimization. The increasing application of SRM-MS should enable fast, sensitive, and robust methods with the potential for use in clinical studies involving sampling of serum or plasma. Understanding the molecular mechanisms and identifying potential biomarkers for risk assessment, diagnosis, prognosis, and prediction of drug response goes toward the implementation of translational medicine strategies for improved treatment of patients with psychiatric disorders and other debilitating diseases.

  19. Report on thermic effects in the study of the control and propagation of nuclear reactions

    International Nuclear Information System (INIS)

    Naudet, R.

    It is very likely that nuclear reactions in natural reactors are governed by temperature, chiefly as a result of the moderation rate when the water density is altered. Since reactors operate under high pressure, with supercritical water, high temperatures (at least 350 to 400 0 C in some instances) are required in order to stabilize the reactors. Some typical calculations are shown in order to illustrate the changes in the control temperature during irradiation. The speed and, therefore, the duration of reactions is determined by the need to maintain the necessary temperature required for criticality, with heat dissipation conditions taken into account. Apparent measured durations are compatible with heat dissipation by simple conduction. However, it is likely that convection currents exist, and that their effects are superimposed on those of simple conduction. Reaction propagation must also be taken into consideration since criticality cannot be realized simultaneously at every point. The presence of impurities such as gadolinium or samarium in the mineral ore allows reactions to propagate in initially subcritical increments, through progressive breakdown of the impurities by means of neutronic diffusion. However, it has been shown that this phenomenon is seriously affected by thermic effects. Typical calculations are presented. Results clearly depend on temperature distribution hypotheses; sufficient thermic coupling can totally inhibit reaction propagation. It is concluded that, if convection currents are present, propagation is favored inversely with respect to the currents, and therefore a priori downstream of the reactors. 6 figures

  20. Simulating the control of molecular reactions via modulated light fields: from gas phase to solution

    Science.gov (United States)

    Thallmair, Sebastian; Keefer, Daniel; Rott, Florian; de Vivie-Riedle, Regina

    2017-04-01

    Over the past few years quantum control has proven to be very successful in steering molecular processes. By combining theory with experiment, even highly complex control aims were realized in the gas phase. In this topical review, we illustrate the past achievements on several examples in the molecular context. The next step for the quantum control of chemical processes is to translate the fruitful interplay between theory and experiment to the condensed phase and thus to the regime where chemical synthesis can be supported. On the theory side, increased efforts to include solvent effects in quantum control simulations were made recently. We discuss two major concepts, namely an implicit description of the environment via the density matrix algorithm and an explicit inclusion of solvent molecules. By application to chemical reactions, both concepts conclude that despite environmental perturbations leading to more complex control tasks, efficient quantum control in the condensed phase is still feasible.

  1. Global control of reaction wheel pendulum through energy regulation and extended linearization of the state variables

    Directory of Open Access Journals (Sweden)

    Oscar D. Montoya-Giraldo

    2014-01-01

    Full Text Available This paper presents the design and simulation of a global controller for the Reaction Wheel Pendulum system using energy regulation and extended linearization methods for the state feedback. The proposed energy regulation is based on the gradual reduction of the energy of the system to reach the unstable equilibrium point. The signal input for this task is obtained from the Lyapunov stability theory. The extended state feedback controller design is used to get a smooth nonlinear function that extends the region of operation to a bigger range, in contrast with the static linear state feedback obtained through the method of approximate linearization around an operating point. The general designed controller operates with a switching between the two control signals depending upon the region of operation; perturbations are applied in the control signal and the (simulated measured variables to verify the robustness and efficiency of the controller. Finally, simulations and tests using the model of the reaction wheel pendulum system, allow to observe the versatility and functionality of the proposed controller in the entire operation region of the pendulum.

  2. Engineering Cu surfaces for the electrocatalytic conversion of CO2: Controlling selectivity toward oxygenates and hydrocarbons

    Science.gov (United States)

    Hahn, Christopher; Hatsukade, Toru; Kim, Youn-Geun; Vailionis, Arturas; Baricuatro, Jack H.; Higgins, Drew C.; Nitopi, Stephanie A.; Soriaga, Manuel P.; Jaramillo, Thomas F.

    2017-01-01

    In this study we control the surface structure of Cu thin-film catalysts to probe the relationship between active sites and catalytic activity for the electroreduction of CO2 to fuels and chemicals. Here, we report physical vapor deposition of Cu thin films on large-format (∼6 cm2) single-crystal substrates, and confirm epitaxial growth in the , , and orientations using X-ray pole figures. To understand the relationship between the bulk and surface structures, in situ electrochemical scanning tunneling microscopy was conducted on Cu(100), (111), and (751) thin films. The studies revealed that Cu(100) and (111) have surface adlattices that are identical to the bulk structure, and that Cu(751) has a heterogeneous kinked surface with (110) terraces that is closely related to the bulk structure. Electrochemical CO2 reduction testing showed that whereas both Cu(100) and (751) thin films are more active and selective for C–C coupling than Cu(111), Cu(751) is the most selective for >2e− oxygenate formation at low overpotentials. Our results demonstrate that epitaxy can be used to grow single-crystal analogous materials as large-format electrodes that provide insights on controlling electrocatalytic activity and selectivity for this reaction. PMID:28533377

  3. Activity and selectivity regulation of synthesis gas reaction over supported ruthenium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, K; Nobusawa, T; Fukushima, T; Tominaga, H

    1985-01-01

    The catalytic activities of supported ruthenium for synthesis-gas conversion to hydrocarbons was found to be in the following order: TiOS > Nb2O3 > ZrO2 > SiO2 > Ta2O5 > Al2O3 > V2O5 > MoO3 > WO3 > MnO2 > ZnO. Turnover frequencies of the supported ruthenium increased with decrease in dispersion of the metal particles for every carrier material. Even the activities per unit weight of metals were higher for low-dispersion ruthenium of Al2O3, TiO2, and ZrO2. The chain-growth probability of a hydrocarbon product, which is characterized by the Schulz-Flory distribution, increased markedly with decrease in the metal dispersion irrespective of the carrier material. The catalytic activity of ruthenium particles with a dispersed ruthenium increased almost linearly with an increase in reaction pressure (up to at least 2.0 MPa). 23 references, 10 figures, 3 tables.

  4. Interesterification reaction activity, fatty acid composition and selectivity ratio of soybean oil

    Directory of Open Access Journals (Sweden)

    El-Shattory, Y.

    1998-12-01

    Full Text Available The interesterification reaction was carried out by adding oleic acid to soybean oil by ratio 1:2 w/w under different conditions of temperature, stirring and catalyst percentages. Assessment of the interesterification of oils was reported by determination of saponification value, iodine value and fatty acids composition. This study showed that linolenic acid which is responsible for flavour instability of soybean oil and consider as primary factor contributing to deterioration of this oil could be reduced to less than or equals 3%.

    Se han llevado a cabo reacciones de interesterificación mediante la adición de ácido oleico a aceite de soja en la relación 1:2 w/w bajo diferentes condiciones de temperatura, agitación y porcentaje de catalizador. La evaluación de la interesterificación de los aceites se realizó por determinación del índice de saponificación, el índice de iodo y la composición en ácidos grasos. Este estudio mostró que el ácido linolénico, que es responsable de la inestabilidad del flavor del aceite de soja y considerado como factor primario que contribuye a la deterioración de este aceite, podría ser reducido a cantidades menores o iguales al 3%.

  5. High-Resolution State-Selected Ion-Molecule Reaction Studies Using Pulsed Field Ionization Photoelectron-Secondary Ion Coincidence Method

    National Research Council Canada - National Science Library

    Qian, X

    2003-01-01

    We have developed an octopole-quadrupole photoionization apparatus at the Advanced Light Source for absolute integral cross-section measurements of rovibrational-state-selected ion-molecule reactions...

  6. Theoretical description of spin-selective reactions of radical pairs diffusing in spherical 2D and 3D microreactors

    International Nuclear Information System (INIS)

    Ivanov, Konstantin L.; Lukzen, Nikita N.; Sadovsky, Vladimir M.

    2015-01-01

    In this work, we treat spin-selective recombination of a geminate radical pair (RP) in a spherical “microreactor,” i.e., of a RP confined in a micelle, vesicle, or liposome. We consider the microreactor model proposed earlier, in which one of the radicals is located at the center of the micelle and the other one undergoes three-dimensional diffusion inside the micelle. In addition, we suggest a two-dimensional model, in which one of the radicals is located at the “pole” of the sphere, while the other one diffuses on the spherical surface. For this model, we have obtained a general analytical expression for the RP recombination yield in terms of the free Green function of two-dimensional diffusion motion. In turn, this Green function is expressed via the Legendre functions and thus takes account of diffusion over a restricted spherical surface and its curvature. The obtained expression allows one to calculate the RP recombination efficiency at an arbitrary magnetic field strength. We performed a comparison of the two models taking the same geometric parameters (i.e., the microreactor radius and the closest approach distance of the radicals), chemical reactivity, magnetic interactions in the RP and diffusion coefficient. Significant difference between the predictions of the two models is found, which is thus originating solely from the dimensionality effect: for different dimensionality of space, the statistics of diffusional contacts of radicals becomes different altering the reaction yield. We have calculated the magnetic field dependence of the RP reaction yield and chemically induced dynamic nuclear polarization of the reaction products at different sizes of the microreactor, exchange interaction, and spin relaxation rates. Interestingly, due to the intricate interplay of diffusional contacts of reactants and spin dynamics, the dependence of the reaction yield on the microreactor radius is non-monotonous. Our results are of importance for (i) interpreting

  7. Pediatric selective mutism therapy: a randomized controlled trial.

    Science.gov (United States)

    Esposito, Maria; Gimigliano, Francesca; Barillari, Maria R; Precenzano, Francesco; Ruberto, Maria; Sepe, Joseph; Barillari, Umberto; Gimigliano, Raffaele; Militerni, Roberto; Messina, Giovanni; Carotenuto, Marco

    2017-10-01

    Selective mutism (SM) is a rare disease in children coded by DSM-5 as an anxiety disorder. Despite the disabling nature of the disease, there is still no specific treatment. The aims of this study were to verify the efficacy of six-month standard psychomotor treatment and the positive changes in lifestyle, in a population of children affected by SM. Randomized controlled trial registered in the European Clinical Trials Registry (EuDract 2015-001161-36). University third level Centre (Child and Adolescent Neuropsychiatry Clinic). Study population was composed by 67 children in group A (psychomotricity treatment) (35 M, mean age 7.84±1.15) and 71 children in group B (behavioral and educational counseling) (37 M, mean age 7.75±1.36). Psychomotor treatment was administered by trained child therapists in residential settings three times per week. Each child was treated for the whole period by the same therapist and all the therapists shared the same protocol. The standard psychomotor session length is of 45 minutes. At T0 and after 6 months (T1) of treatments, patients underwent a behavioral and SM severity assessment. To verify the effects of the psychomotor management, the Child Behavior Checklist questionnaire (CBCL) and Selective Mutism Questionnaire (SMQ) were administered to the parents. After 6 months of psychomotor treatment SM children showed a significant reduction among CBCL scores such as in social relations, anxious/depressed, social problems and total problems (Pselective mutism, even if further studies are needed. The present study identifies in psychomotricity a safe and efficacy therapy for pediatric selective mutism.

  8. Mechanical stress-controlled tunable active frequency-selective surface

    Science.gov (United States)

    Huang, Bo-Cin; Hong, Jian-Wei; Lo, Cheng-Yao

    2017-01-01

    This study proposes a tunable active frequency-selective surface (AFSS) realized by mechanically expanding or contracting a split-ring resonator (SRR) array. The proposed AFSS transfers mechanical stress from its elastic substrate to the top of the SRR, thereby achieving electromagnetic (EM) modulation without the need for an additional external power supply, meeting the requirements for the target application: the invisibility cloak. The operating mechanism of the proposed AFSS differs from those of other AFSSs, supporting modulations in arbitrary frequencies in the target range. The proposed stress-controlled or strain-induced EM modulation proves the existence of an identical and linear relationship between the strain gradient and the frequency shift, implying its suitability for other EM modulation ranges and applications.

  9. Protective Controller against Cascade Outages with Selective Harmonic Compensation Function

    Science.gov (United States)

    Abramovich, B. N.; Kuznetsov, P. A.; Sychev, Yu A.

    2018-05-01

    The paper presents data on the power quality and development of protective devices for the power networks with distributed generation (DG).The research has shown that power quality requirements for DG networks differ from conventional ones. That is why main tendencies, protective equipment and filters should be modified. There isa developed algorithm for detection and prevention of cascade outages that can lead to the blackoutin DG networks and there was a proposed structural scheme for a new active power filter for selective harmonics compensation. Analysis of these theories and equipment led to the development of protective device that could monitor power balance and cut off non-important consumers. The last part of the article describes a microcontroller prototype developed for connection to the existing power station control center.

  10. State departments for the selection and control of school textbooks

    Directory of Open Access Journals (Sweden)

    María López García

    2012-02-01

    Full Text Available The article studies the State Commissions for the regulation of Schoolbooks, instituted in Argentine at the beginning of the 20th-century. The analysis exhibits a gradual liberalization of the prescriptions and a reassignment of decisions to the publishers, as well as the institution of schoolbooks as ineludible tool of the pedagogical methodology throughout that century. The growing of the publishing industry resulted in a displacement of the functions of control and selection of the produced teaching materials from the State on teachers and publishing companies. The bonds between State proposals and market technologies entailed a state validation of the companies’ conveniences; one of its more harmful consequences was their increasing meddling in the pedagogical methodology to implement in the school.

  11. Metformin selectively targets redox control of complex I energy transduction

    Directory of Open Access Journals (Sweden)

    Amy R. Cameron

    2018-04-01

    Full Text Available Many guanide-containing drugs are antihyperglycaemic but most exhibit toxicity, to the extent that only the biguanide metformin has enjoyed sustained clinical use. Here, we have isolated unique mitochondrial redox control properties of metformin that are likely to account for this difference. In primary hepatocytes and H4IIE hepatoma cells we found that antihyperglycaemic diguanides DG5-DG10 and the biguanide phenformin were up to 1000-fold more potent than metformin on cell signalling responses, gluconeogenic promoter expression and hepatocyte glucose production. Each drug inhibited cellular oxygen consumption similarly but there were marked differences in other respects. All diguanides and phenformin but not metformin inhibited NADH oxidation in submitochondrial particles, indicative of complex I inhibition, which also corresponded closely with dehydrogenase activity in living cells measured by WST-1. Consistent with these findings, in isolated mitochondria, DG8 but not metformin caused the NADH/NAD+ couple to become more reduced over time and mitochondrial deterioration ensued, suggesting direct inhibition of complex I and mitochondrial toxicity of DG8. In contrast, metformin exerted a selective oxidation of the mitochondrial NADH/NAD+ couple, without triggering mitochondrial deterioration. Together, our results suggest that metformin suppresses energy transduction by selectively inducing a state in complex I where redox and proton transfer domains are no longer efficiently coupled. Keywords: Diabetes, Metformin, Mitochondria, NADH, NAD+

  12. Pre-vaccination care-seeking in females reporting severe adverse reactions to HPV vaccine. A registry based case-control study

    DEFF Research Database (Denmark)

    Mølbak, Kåre; Hansen, Niels Dalum; Valentiner-Branth, Palle

    2016-01-01

    to the DMA of suspected severe adverse reactions.We selected controls without reports of adverse reactions from the Danish vaccination registry and matched by year of vaccination, age of vaccination, and municipality, and obtained from the Danish National Patient Registry and The National Health Insurance...... vaccination programme has declined. The aim of the present study was to determine health care-seeking prior to the first HPV vaccination among females who suspected adverse reactions to HPV vaccine. Methods In this registry-based case-control study, we included as cases vaccinated females with reports...... Service Register the history of health care usage two years prior to the first vaccine. We analysed the data by logistic regression while adjusting for the matching variables. Results The study included 316 cases who received first HPV vaccine between 2006 and 2014. Age range of cases was 11 to 52 years...

  13. Employee reactions to the use of management control systems in hospitals: motivation vs. threat.

    Science.gov (United States)

    Lopez-Valeiras, Ernesto; Gomez-Conde, Jacobo; Lunkes, Rogerio Joao

    Management control systems (such as budgets or balanced scorecards) are formal procedures used by managers to promote employee behavior aligned with organisational objectives. Employees may react to these control systems by either becoming more motivated or perceiving them as a threat. The aim of this paper is to determine the extent to which hospital ownership (public or private), professional group (physician, nurse, pharmacist or administrative employee), type of contract (fixed or temporary), gender and tenure can condition employee reaction to management control systems. We conducted the study in the three largest hospitals in the State of Santa Catarina (Brazil), two public (federal and state-owned) and one private (non-profit organisation). Physicians, nurses, pharmacists and administrative employees received a questionnaire between October 2013 and January 2014 concerning their current perceptions. We obtained 100 valid responses and conducted an ANOVA variance analysis. Our results show that the effect of management control systems on employees differs according to hospital ownership, professional group and type of contract. However, no significant evidence was found concerning gender or tenure. The results obtained contribute to creating specific knowledge on the reactions of employees to the use of management control systems in hospitals. This information may be important in adapting management control systems to the characteristics of the hospital and its employees, which may in turn contribute to reducing dysfunctional worker behavior. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. Visual and auditory reaction time for air traffic controllers using quantitative electroencephalograph (QEEG) data.

    Science.gov (United States)

    Abbass, Hussein A; Tang, Jiangjun; Ellejmi, Mohamed; Kirby, Stephen

    2014-12-01

    The use of quantitative electroencephalograph in the analysis of air traffic controllers' performance can reveal with a high temporal resolution those mental responses associated with different task demands. To understand the relationship between visual and auditory correct responses, reaction time, and the corresponding brain areas and functions, air traffic controllers were given an integrated visual and auditory continuous reaction task. Strong correlations were found between correct responses to the visual target and the theta band in the frontal lobe, the total power in the medial of the parietal lobe and the theta-to-beta ratio in the left side of the occipital lobe. Incorrect visual responses triggered activations in additional bands including the alpha band in the medial of the frontal and parietal lobes, and the Sensorimotor Rhythm in the medial of the parietal lobe. Controllers' responses to visual cues were found to be more accurate but slower than their corresponding performance on auditory cues. These results suggest that controllers are more susceptible to overload when more visual cues are used in the air traffic control system, and more errors are pruned as more auditory cues are used. Therefore, workload studies should be carried out to assess the usefulness of additional cues and their interactions with the air traffic control environment.

  15. Adaptive FTC based on Control Allocation and Fault Accommodation for Satellite Reaction Wheels

    DEFF Research Database (Denmark)

    Baldi, P.; Blanke, Mogens; Castaldi, P.

    2016-01-01

    and fault accommodation module directly exploiting the on-line fault estimates. The use of the nonlinear geometric approach and radial basis function neural networks allows to obtain a precise fault isolation, independently from the knowledge of aerodynamic disturbance parameters, and to design generalised......This paper proposes an active fault tolerant control scheme to cope with faults or failures affecting the flywheel spin rate sensors or satellite reaction wheel motors. The active fault tolerant control system consists of a fault detection and diagnosis module along with a control allocation...... estimation filters, which do not need a priori information about the internal model of the signal to be estimated. The adaptive control allocation and sensor fault accommodation can handle both temporal faults and failures. Simulation results illustrate the convincing fault correction and attitude control...

  16. Profile of rheumatology patients willing to report adverse drug reactions: bias from selective reporting

    Directory of Open Access Journals (Sweden)

    Protić D

    2016-02-01

    Full Text Available Dragana Protić,1 Nada Vujasinović-Stupar,2 Zoran Bukumirić,3 Slavica Pavlov-Dolijanović,4 Snežana Baltić,5 Slavica Mutavdžin,6 Ljiljana Markovic-Denić,7 Marija Zdravković,8 Zoran Todorović1 1Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; 2Department 2, Institute of Rheumatology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; 3Institute for Medical Statistics and Informatics, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; 4Department 5, Institute of Rheumatology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; 5Department 5, Institute of Rheumatology, Belgrade, Serbia; 6Institute of Physiology “Rihard Burjan”, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; 7Institute of Epidemiology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia; 8Department of Cardiology, Medical Center “Bežanijska kosa”, Faculty of Medicine, University of Belgrade, Belgrade, Serbia Background: Adverse drug reactions (ADRs have a significant impact on human health and health care costs. The aims of our study were to determine the profile of rheumatology patients willing to report ADRs and to identify bias in such a reporting system. Methods: Semi-intensive ADRs reporting system was used in our study. Patients willing to participate (N=261 completed the questionnaire designed for the purpose of the study at the hospital admission. They were subsequently classified into two groups according to their ability to identify whether they had experienced ADRs during the previous month. Group 1 included 214 out of 261 patients who were able to identify ADRs, and group 2 consisted of 43 out of 261 patients who were not able to identify ADRs in their recent medical history. Results: Group 1 patients were more significantly aware of their diagnosis than the patients from group 2. Marginal significance was found

  17. Collimator Selection in Nuclear Medicine Imaging Using I-123 Generated by Te-124 Reaction

    International Nuclear Information System (INIS)

    Kim, Hee Joung; Son, Hye Kyung; Nam, Ki Pyo; Lee, Hee Kyung; Bong, Joung Kyun

    1996-01-01

    In the case of I-123 from the Te-124(p,2n)reaction, the radionuclidic impurity is the high-energy gamma-emitting I-124, which interferes greatly with nuclear medicine images. The choice of a collimator can affect the quality of clinical SPECT images of [I-123]MIBG, [I-123]μ-CIT, or [I-123]IPT. The tradeoffs that two different collimators make among spatial resolution, sensitivity, and scatter were studied by imaging a line source at 5 cm, 10 cm, 15 cm distance using a number of plexiglass sheets between source and collimator, petridish, two-dimensional Hoffman brain phantom, Jaszczak phantom, and three-dimensional Hoffman brain phantom after filling with I-123. (FWHM, FWTM, Sensitivity) for low-energy ultrahigh-resolution parallel-hole(LEUHRP) collimator and medium-energy general-purpose(MEGP) collimator were measured as (9.27 mm, 61.27 mm, 129 CPM/μCi) and (10.53 mm, 23.17 mm, 105CPM/μ/Ci), respectively. The image quality of two-dimensional Hoffman brain phantom with LEUHRP looked better than the one with MEGP. However, the image quality of Jaszczak phantom and three-dimensional Hoffman brain phantom with LEUHRP looked much worse than the one with MEGP because of scatter contributions in three-dimensional imaging situation. The results suggest that the MEGP is preferable to LEUHRP for three-dimensional imaging studies of [I-123]MIBG, [I-123] β-CIT, or [I-123] IPT.

  18. Amorphous saturated Cerium-Tungsten-Titanium oxide nanofibers catalysts for NOx selective catalytic reaction

    DEFF Research Database (Denmark)

    Dankeaw, Apiwat; Gualandris, Fabrizio; Silva, Rafael Hubert

    2018-01-01

    experiments at the best working conditions (dry and in absence of SO2) are performed to characterize the intrinsic catalytic behavior of the new catalysts. At temeprature lower than 300 °C, superior NOx conversion properties of the amorphous TiOx nanofibers over the crystallized TiO2 (anatase) nanofibers......Herein for the first time, Ce0.184W0.07Ti0.748O2-δ nanofibers are prepared by electrospinning to serve as catalyst in the selective catalytic reduction (SCR) process. The addition of cerium is proven to inhibit crystallization of TiO2, yielding an amorphous TiOx-based solid solution stable up...... temperatures (catalysts in a wide range...

  19. Controllable synthesis of silver and silver sulfide nanocrystals via selective cleavage of chemical bonds

    International Nuclear Information System (INIS)

    Tang Aiwei; Wang Yu; Ye Haihang; Zhou Chao; Yang Chunhe; Li Xu; Peng Hongshang; Zhang Fujun; Hou Yanbing; Teng Feng

    2013-01-01

    A one-step colloidal process has been adopted to prepare silver (Ag) and silver sulfide (Ag 2 S) nanocrystals, thus avoiding presynthesis of an organometallic precursor and the injection of a toxic phosphine agent. During the reaction, a layered intermediate compound is first formed, which then acts as a precursor, decomposing into the nanocrystals. The composition of the as-obtained products can be controlled by selective cleavage of S–C bonds or Ag–S bonds. Pure Ag 2 S nanocrystals can be obtained by directly heating silver acetate (Ag(OAc)) and n-dodecanethiol (DDT) at 200 ° C without any surfactant, and pure Ag nanocrystals can be synthesized successfully if the reaction temperature is reduced to 190 ° C and the amount of DDT is decreased to 1 ml in the presence of a non-coordinating organic solvent (1-octadecene, ODE). Otherwise, the mixture of Ag and Ag 2 S is obtained by directly heating Ag(OAc) in DDT by increasing the reaction temperature or in a mixture of DDT and ODE at 200 ° C. The formation mechanism has been discussed in detail in terms of selective S–C and Ag–S bond dissociation due to the nucleophilic attack of DDT and the lower bonding energy of Ag–S. Interestingly, some products can easily self-assemble into two- or three-dimensional (2D or 3D) highly ordered superlattice structures on a copper grid without any additional steps. The excess DDT plays a key role in the superlattice structure due to the bundling and interdigitation of the thiolate molecules adsorbed on the as-obtained nanocrystals. (paper)

  20. Selecting a Control Strategy for Plug and Process Loads

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, C.; Sheppy, M.; Brackney, L.; Pless, S.; Torcellini, P.

    2012-09-01

    Plug and Process Loads (PPLs) are building loads that are not related to general lighting, heating, ventilation, cooling, and water heating, and typically do not provide comfort to the building occupants. PPLs in commercial buildings account for almost 5% of U.S. primary energy consumption. On an individual building level, they account for approximately 25% of the total electrical load in a minimally code-compliant commercial building, and can exceed 50% in an ultra-high efficiency building such as the National Renewable Energy Laboratory's (NREL) Research Support Facility (RSF) (Lobato et al. 2010). Minimizing these loads is a primary challenge in the design and operation of an energy-efficient building. A complex array of technologies that measure and manage PPLs has emerged in the marketplace. Some fall short of manufacturer performance claims, however. NREL has been actively engaged in developing an evaluation and selection process for PPLs control, and is using this process to evaluate a range of technologies for active PPLs management that will cap RSF plug loads. Using a control strategy to match plug load use to users' required job functions is a huge untapped potential for energy savings.

  1. Pump-shaped dump optimal control reveals the nuclear reaction pathway of isomerization of a photoexcited cyanine dye.

    Science.gov (United States)

    Dietzek, Benjamin; Brüggemann, Ben; Pascher, Torbjörn; Yartsev, Arkady

    2007-10-31

    Using optimal control as a spectroscopic tool we decipher the details of the molecular dynamics of the essential multidimensional excited-state photoisomerization - a fundamental chemical reaction of key importance in biology. Two distinct nuclear motions are identified in addition to the overall bond-twisting motion: Initially, the reaction is dominated by motion perpendicular to the torsion coordinate. At later times, a second optically active vibration drives the system along the reaction path to the bottom of the excited-state potential. The time scales of the wavepacket motion on a different part of the excited-state potential are detailed by pump-shaped dump optimal control. This technique offers new means to control a chemical reaction far from the Franck-Condon point of absorption and to map details of excited-state reaction pathways revealing unique insights into the underlying reaction mechanism.

  2. Field-based random sampling without a sampling frame: control selection for a case-control study in rural Africa.

    Science.gov (United States)

    Crampin, A C; Mwinuka, V; Malema, S S; Glynn, J R; Fine, P E

    2001-01-01

    Selection bias, particularly of controls, is common in case-control studies and may materially affect the results. Methods of control selection should be tailored both for the risk factors and disease under investigation and for the population being studied. We present here a control selection method devised for a case-control study of tuberculosis in rural Africa (Karonga, northern Malawi) that selects an age/sex frequency-matched random sample of the population, with a geographical distribution in proportion to the population density. We also present an audit of the selection process, and discuss the potential of this method in other settings.

  3. Adaptive extended-state observer-based fault tolerant attitude control for spacecraft with reaction wheels

    Science.gov (United States)

    Ran, Dechao; Chen, Xiaoqian; de Ruiter, Anton; Xiao, Bing

    2018-04-01

    This study presents an adaptive second-order sliding control scheme to solve the attitude fault tolerant control problem of spacecraft subject to system uncertainties, external disturbances and reaction wheel faults. A novel fast terminal sliding mode is preliminarily designed to guarantee that finite-time convergence of the attitude errors can be achieved globally. Based on this novel sliding mode, an adaptive second-order observer is then designed to reconstruct the system uncertainties and the actuator faults. One feature of the proposed observer is that the design of the observer does not necessitate any priori information of the upper bounds of the system uncertainties and the actuator faults. In view of the reconstructed information supplied by the designed observer, a second-order sliding mode controller is developed to accomplish attitude maneuvers with great robustness and precise tracking accuracy. Theoretical stability analysis proves that the designed fault tolerant control scheme can achieve finite-time stability of the closed-loop system, even in the presence of reaction wheel faults and system uncertainties. Numerical simulations are also presented to demonstrate the effectiveness and superiority of the proposed control scheme over existing methodologies.

  4. Reaching to a featured formula to deduce the energy of the heaviest particles producing from the controlled thermonuclear fusion reactions

    Science.gov (United States)

    Majeed, Raad H.; Oudah, Osamah N.

    2018-05-01

    Thermonuclear fusion reaction plays an important role in developing and construction any power plant system. Studying the physical behavior for the possible mechanism governed energies released by the fusion products to precise understanding the related kinematics. In this work a theoretical formula controlled the general applied thermonuclear fusion reactions is achieved to calculating the fusion products energy depending upon the reactants physical properties and therefore, one can calculate other parameters governed a given reaction. By using this formula, the energy spectrum of 4He produced from T-3He fusion reaction has been sketched with respect to reaction angle and incident energy ranged from (0.08-0.6) MeV.

  5. Gold(I)-catalyzed diazo cross-coupling: a selective and ligand-controlled denitrogenation/cyclization cascade.

    Science.gov (United States)

    Xu, Guangyang; Zhu, Chenghao; Gu, Weijin; Li, Jian; Sun, Jiangtao

    2015-01-12

    An unprecedented gold-catalyzed ligand-controlled cross-coupling of diazo compounds by sequential selective denitrogenation and cyclization affords N-substituted pyrazoles in a position-switchable mode. This novel transformation features selective decomposition of one diazo moiety and simultaneous preservation of the other one from two substrates. Notably, the choice of the ancillary ligand to the gold complex plays a pivotal role on the chemo- and regioselectivity of the reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Reaction and catalyst engineering to exploit kinetically controlled whole-cell multistep biocatalysis for terminal FAME oxyfunctionalization.

    Science.gov (United States)

    Schrewe, Manfred; Julsing, Mattijs K; Lange, Kerstin; Czarnotta, Eik; Schmid, Andreas; Bühler, Bruno

    2014-09-01

    The oxyfunctionalization of unactivated C−H bonds can selectively and efficiently be catalyzed by oxygenase-containing whole-cell biocatalysts. Recombinant Escherichia coli W3110 containing the alkane monooxygenase AlkBGT and the outer membrane protein AlkL from Pseudomonas putida GPo1 have been shown to efficiently catalyze the terminal oxyfunctionalization of renewable fatty acid methyl esters yielding bifunctional products of interest for polymer synthesis. In this study, AlkBGTL-containing E. coli W3110 is shown to catalyze the multistep conversion of dodecanoic acid methyl ester (DAME) via terminal alcohol and aldehyde to the acid, exhibiting Michaelis-Menten-type kinetics for each reaction step. In two-liquid phase biotransformations, the product formation pattern was found to be controlled by DAME availability. Supplying DAME as bulk organic phase led to accumulation of the terminal alcohol as the predominant product. Limiting DAME availability via application of bis(2-ethylhexyl)phthalate (BEHP) as organic carrier solvent enabled almost exclusive acid accumulation. Furthermore, utilization of BEHP enhanced catalyst stability by reducing toxic effects of substrate and products. A further shift towards the overoxidized products was achieved by co-expression of the gene encoding the alcohol dehydrogenase AlkJ, which was shown to catalyze efficient and irreversible alcohol to aldehyde oxidation in vivo. With DAME as organic phase, the aldehyde accumulated as main product using resting cells containing AlkBGT, AlkL, as well as AlkJ. This study highlights the versatility of whole-cell biocatalysis for synthesis of industrially relevant bifunctional building blocks and demonstrates how integrated reaction and catalyst engineering can be implemented to control product formation patterns in biocatalytic multistep reactions. © 2014 Wiley Periodicals, Inc.

  7. Thermal decomposition of specifically phosphorylated D-glucoses and their role in the control of the Maillard reaction.

    Science.gov (United States)

    Yaylayan, Varoujan A; Machiels, David; Istasse, Louis

    2003-05-21

    One of the main shortcomings of the information available on the Maillard reaction is the lack of knowledge to control the different pathways, especially when it is desired to direct the reaction away from the formation of carcinogenic and other toxic substances to more aroma and color generation. The use of specifically phosphorylated sugars may impart some elements of control over the aroma profile generated by the Maillard reaction. Thermal decomposition of 1- and 6-phosphorylated glucoses was studied in the presence and absence of ammonia and selected amino acids through pyrolysis/gas chromatography/mass spectrometry using nonpolar PLOT and medium polar DB-1 columns. The analysis of the data has indicated that glucose-1-phosphate relative to glucose undergoes more extensive phosphate-catalyzed ring opening followed by formation of sugar-derived reactive intermediates as was indicated by a 9-fold increase in the amount of trimethylpyrazine and a 5-fold increase in the amount of 2,3-dimethylpyrazine, when pyrolyzed in the presence of glycine. In addition, glucose-1-phosphate alone generated a 6-fold excess of acetol as compared to glucose. On the other hand, glucose-6-phosphate enhanced retro-aldol reactions initiated from a C-6 hydroxyl group and increased the subsequent formation of furfural and 4-cyclopentene-1,3-dione. Furthermore, it also stabilized 1- and 3-deoxyglucosone intermediates and enhanced the formation of six carbon atom-containing Maillard products derived directly from them through elimination reactions such as 1,6-dimethyl-2,4-dihydroxy-3-(2H)-furanone (acetylformoin), 2-acetylpyrrole, 5-methylfurfural, 5-hydroxymethylfurfural, and 4-hydroxy-2,5-dimethyl-3-(2H)-furanone (Furaneol), due to the enhanced leaving group ability of the phosphate moiety at the C-6 carbon. However, Maillard products generated through the nucleophilic action of the C-6 hydroxyl group such as 2-acetylfuran and 2,3-dihydro-3,5-dihydroxy-4H-pyran-4-one were retarded, due

  8. Bisindeno-annulated pentacenes with exceptionally high photo-stability and ordered molecular packing: Simple synthesis by a regio-selective Scholl reaction

    KAUST Repository

    Naibi Lakshminarayana, Arun; Chang, Jingjing; Luo, Jie; Zheng, Bin; Huang, Kuo-Wei; Chi, Chunyan

    2015-01-01

    Bisindeno-annulated pentacenes 3a and 3b were synthesized by a simple regio-selective, FeCl3-mediated Scholl reaction from the corresponding 6,13-diaryl pentacene precursors. The fusion of two indeno-units dramatically changes the electronic properties and chemical reactivity of pentacene and the obtained compounds exhibited exceptionally high photo-stability in the solution, with a half-life time of 11.2 (3a) and 32.0 (3b) days under ambient light and air conditions. Ordered molecular packing with a small π-π stacking distance was observed in the single crystals of 3a and 3b. Our research provides a promising strategy to access stable higher order acenes with controlled molecular order. This journal is

  9. Effect of the Gouy phase on the coherent phase control of chemical reactions.

    Science.gov (United States)

    Gordon, Robert J; Barge, Vishal J

    2007-11-28

    We show how the spatial phase of a focused laser beam may be used as a tool for controlling the branching ratio of a chemical reaction. Guoy discovered [Acad. Sci., Paris, C. R. 110, 1250 (1890)] that when an electromagnetic wave passes through a focus its phase increases by pi. In a coherent control scheme involving the absorption of n photons of frequency omega(m) and m photons of frequency omega(n), the overall phase shift produced by the Gouy phase is (n-m)pi. At any given point in space, this phase shift is identical for all reaction products. Nevertheless, if the yields for different reaction channels have different intensity dependencies, the Gouy phase produces a net phase lag between the products that varies with the axial coordinate of the laser focus. We obtain here analytical and numerical values of this phase as the laser focus is scanned across the diameter of the molecular beam, taking into account the Rayleigh range and astigmatism of the laser beam and saturation of the transition. We also show that the modulation depth of the interference pattern may be increased by optimizing the relative intensities of the two fields.

  10. Chirality-controlled spontaneous twisting of crystals due to thermal topochemical reaction.

    Science.gov (United States)

    Rai, Rishika; Krishnan, Baiju P; Sureshan, Kana M

    2018-03-20

    Crystals that show mechanical response against various stimuli are of great interest. These stimuli induce polymorphic transitions, isomerizations, or chemical reactions in the crystal and the strain generated between the daughter and parent domains is transcribed into mechanical response. We observed that the crystals of modified dipeptide LL (N 3 -l-Ala-l-Val-NHCH 2 C≡CH) undergo spontaneous twisting to form right-handed twisted crystals not only at room temperature but also at 0 °C over time. Using various spectroscopic techniques, we have established that the twisting is due to the spontaneous topochemical azide-alkyne cycloaddition (TAAC) reaction at room temperature or lower temperatures. The rate of twisting can be increased by heating, exploiting the faster kinetics of the TAAC reaction at higher temperatures. To address the role of molecular chirality in the direction of twisting the enantiomer of dipeptide LL, N 3 -d-Ala-d-Val-NHCH 2 C≡CH (DD), was synthesized and topochemical reactivity and mechanoresponse of its crystals were studied. We have found that dipeptide DD not only underwent TAAC reaction, giving 1,4-triazole-linked pseudopolypeptides of d-amino acids, but also underwent twisting with opposite handedness (left-handed twisting), establishing the role of molecular chirality in controlling the direction of mechanoresponse. This paper reports ( i ) a mechanical response due to a thermal reaction and ( ii ) a spontaneous mechanical response in crystals and ( iii ) explains the role of molecular chirality in the handedness of the macroscopic mechanical response.

  11. Energy transfer mechanisms in photobiological reactions. Final report, 1 April 1960--31 March 1979. [Photodynamic processes in selected biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Spikes, J.D.

    1979-03-31

    This project was concerned primarily with studies of the mechanisms of the sensitized photooxidation of selected biomolecules using a variety of phtosensitizers. Such reactions are often termed photodynamic processes. In particular we have carried out steady-state kinetic studies, flash photolysis and spectral studies, and product formation studies of the sensitized photooxidation of the five susceptible amino acids (cycteine, histidine, methonine, tryptophan, and tyrosine) and their derivatives, as well as purines and pyrimidines. A number of studies were also carried out on the mechanisms of the photodynamic inactivation of enzymes (trypsin, ribonuclease, lysozyme). Mechanism of photosensitization were studied using a variety of sensitizers including flavins, porphyrins, and a number of synthetic dyes (substituted fluoresceins, acridines, thyazines).

  12. Controllable synthesis of Co3O4 nanocrystals as efficient catalysts for oxygen reduction reaction

    Science.gov (United States)

    Li, Baoying; Zhang, Yihe; Du, Ruifeng; Liu, Lei; Yu, Xuelian

    2018-03-01

    The electrochemical oxygen reduction reaction (ORR) has received great attention due to its importance in fuel cells and metal-air batteries. Here, we present a simple approach to prepare non-noble metal catalyst-Co3O4 nanocrystals (NCs). The particle size and shape were simply controlled by different types and concentrations of metal precursor. Furthermore, different sizes and shapes of Co3O4 NCs are explored as electrocatalysts for ORR, and it has been observed that particles with a similar shape, and smaller particle size led to greater catalytic current densities because of the greater surface area. For particles with a comparable size, the shape or crystalline structure governed the activity of the electrocatalytic reactions. Most importantly, the 9 nm-Co3O4 were demonstrated to act as low-cost catalysts for the ORR with a similar performance to that of Pt catalysts.

  13. Ex Vivo Antioxidant Activity of Selected Medicinal Plants against Fenton Reaction-Mediated Oxidation of Biological Lipid Substrates

    Directory of Open Access Journals (Sweden)

    Namratha Pai Kotebagilu

    2015-01-01

    Full Text Available Free radical-mediated oxidation is often linked to various degenerative diseases. Biological substrates with lipids as major components are susceptible to oxygen-derived lipid peroxidation due to their composition. Lipid peroxide products act as biomarkers in evaluating the antioxidant potential of various plants and functional foods. The study focused on evaluation of the antioxidant potential of two extracts (methanol and 80% methanol of four medicinal plants, Andrographis paniculata, Costus speciosus, Canthium parviflorum, and Abrus precatorius, against Fenton reaction-mediated oxidation of three biological lipid substrates; cholesterol, low-density lipoprotein, and brain homogenate. The antioxidant activity of the extracts was measured by thiobarbituric acid reactive substances method. Also, the correlation between the polyphenol, flavonoid content, and the antioxidant activity in biological substrates was analyzed. Results indicated highest antioxidant potential by 80% methanol extract of Canthium parviflorum (97.55%, methanol extract of Andrographis paniculata (72.15%, and methanol extract of Canthium parviflorum (49.55% in cholesterol, low-density lipoprotein, and brain, respectively. The polyphenol and flavonoid contents of methanol extract of Andrographis paniculata in cholesterol (r=0.816 and low-density lipoprotein (r=0.948 and Costus speciosus in brain (r=0.977, polyphenols, and r=0.949, flavonoids correlated well with the antioxidant activity. The findings prove the antioxidant potential of the selected medicinal plants against Fenton reaction in biological lipid substrates.

  14. Light-induced spatial control of pH-jump reaction at smart gel interface.

    Science.gov (United States)

    Techawanitchai, Prapatsorn; Ebara, Mitsuhiro; Idota, Naokazu; Aoyagi, Takao

    2012-11-01

    We proposed here a 'smart' control of an interface movement of proton diffusion in temperature- and pH-responsive hydrogels using a light-induced spatial pH-jump reaction. A photoinitiated proton-releasing reaction of o-nitrobenzaldehyde (NBA) was integrated into poly(N-isopropylacrylamide-o-2-carboxyisopropylacrylamide) (P(NIPAAm-co-CIPAAm)) hydrogels. NBA-integrated hydrogels demonstrated quick release of proton upon UV irradiation, allowing the pH inside the gel to decrease below the pK(a) of P(NIPAAm-co-CIPAAm) within a minute. The NBA-integrated gel was shown to shrink rapidly upon UV irradiation without polymer "skin layer" formation due to a uniform decrease of pH inside the gel. Spatial control of gel shrinking was also created by irradiating UV light to a limited region of the gel through a photomask. The interface of proton diffusion ("active interface") gradually moved toward non-illuminated area. The apparent position of "active interface", however, did not change remarkably above the LCST, while protons continuously diffused outward direction. This is because the "active interface" also moved inward direction as gel shrank above the LCST. As a result, slow movement of the apparent interface was observed. The NBA-integrated gel was also successfully employed for the controlled release of an entrapped dextran in a light controlled manner. This system is highly promising as smart platforms for triggered and programmed transportation of drugs. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Optimal Attitude Control of Agile Spacecraft Using Combined Reaction Wheel and Control Moment Gyroscope Arrays

    Science.gov (United States)

    2015-12-01

    communications between the MicroAuto Box and the ground station computer [58]. SimSat users design experiments in the MATLAB® Simulink environment and use an...Guidance, Control, and Dynamics, vol. 35, no. 4, pp. 1094–1103, 2012. [44] Z. Sun, L. Zhang, G. Jin, and X. Yang, “Analysis of inertia dyadic uncertainty

  16. Evaluation of reaction selectivity at various Pt/C electrocatalysts using a porous microelectrode in the presence of methanol and oxygen

    International Nuclear Information System (INIS)

    Shironita, Sayoko; Zhang, Weiqi; Sakai, Tsukasa; Umeda, Minoru

    2014-01-01

    Pt is most useful metal for various electrochemical reactions as an electrocatalyst. In a direct methanol fuel cell, Pt performs a catalytic activity for both the methanol oxidation reaction and oxygen reduction reaction; therefore, a Pt-based catalyst is used as an anode and a cathode. For the coexistence of methanol and oxygen due to methanol crossover through an electrolyte membrane during the cell operation, the direct methanol fuel cell performance decreases. However, if a higher selective reaction electrocatalyst can be developed, the cell performance will not be suppressed. In this study, the reaction selectivities of seven types of Pt supported on carbon (Pt/C) electrocatalysts were evaluated using a porous microelectrode in the presence of methanol and oxygen. As a result, some Pt/C catalysts showed a methanol oxidation selectivity, while the other catalysts showed an oxygen reduction selectivity. It was found that the percentage of edge-atom in the Pt particle is related to the methanol oxidation selectivity or the oxygen reduction selectivity. Moreover, each current density decreases with the increasing chemical shift in the Pt binding energy

  17. Controlling the selective formation of calcium sulfate polymorphs at room temperature.

    Science.gov (United States)

    Tritschler, Ulrich; Van Driessche, Alexander E S; Kempter, Andreas; Kellermeier, Matthias; Cölfen, Helmut

    2015-03-23

    Calcium sulfate is a naturally abundant and technologically important mineral with a broad scope of applications. However, controlling CaSO4 polymorphism and, with it, its final material properties still represents a major challenge, and to date there is no universal method for the selective production of the different hydrated and anhydrous forms under mild conditions. Herein we report the first successful synthesis of pure anhydrite from solution at room temperature. We precipitated calcium sulfate in alcoholic media at low water contents. Moreover, by adjusting the amount of water in the syntheses, we can switch between the distinct polymorphs and fine-tune the outcome of the reaction, yielding either any desired CaSO4 phase in pure state or binary mixtures with predefined compositions. This concept provides full control over phase selection in CaSO4 mineralization and may allow for the targeted fabrication of corresponding materials for use in various areas. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Selective formation of VO2(A) or VO2(R) polymorph by controlling the hydrothermal pressure

    International Nuclear Information System (INIS)

    Ji Shidong; Zhang Feng; Jin Ping

    2011-01-01

    Missing VO 2 (A) usually occurs during the preparation of VO 2 polymorphs. This leads to an ambiguous understanding of the transformation between VO 2 polymorphs. The calculation of the ground state energies for different VO 2 polymorphs indicated that there is only a small energy gap between VO 2 (A) and VO 2 (R), which destined that the transformation from VO 2 (A) to VO 2 (R) should be pressure sensitive. This hypothesis was verified during the synthesizing of VO 2 polymorphs by reducing V 2 O 5 with oxalic acid through hydrothermal treatment process. Selective formation of pure phase VO 2 (A) or VO 2 (R) was achieved by controlling the hydrothermal pressure through varying the filling ratio at 270 deg. C. It was found that a filling ratio over 0.5 favors the formation of pure VO 2 (R) while a reduced filling ratio to 0.4 or lower results in the formation of VO 2 (A). Based on our experiments, VO 2 (B) nanobelts were always first formed and then it transformed to VO 2 (A) by assembling process at increased temperature or extended reaction time. Under further higher pressure, the VO 2 (A) transformed spontaneously to VO 2 (R) initialized from the volume shrinkage due to the formation of denser VO 2 (R). - Graphical abstract: Selective formation of VO 2 (A) or VO 2 (R) could be achieved by controlling the system pressure through varying the filling ratio during hydrothermal treatment. Highlights: → Selective formation of VO 2 polymorphs by controlling hydrothermal pressure. → Ground state energy characteristics were revealed for the first time. → Phase transformation mechanism was clearly elucidated.

  19. Thermodynamic Vent System for an On-Orbit Cryogenic Reaction Control Engine

    Science.gov (United States)

    Hurlbert, Eric A.; Romig, Kris A.; Jimenez, Rafael; Flores, Sam

    2012-01-01

    A report discusses a cryogenic reaction control system (RCS) that integrates a Joule-Thompson (JT) device (expansion valve) and thermodynamic vent system (TVS) with a cryogenic distribution system to allow fine control of the propellant quality (subcooled liquid) during operation of the device. It enables zero-venting when coupled with an RCS engine. The proper attachment locations and sizing of the orifice are required with the propellant distribution line to facilitate line conditioning. During operations, system instrumentation was strategically installed along the distribution/TVS line assembly, and temperature control bands were identified. A sub-scale run tank, full-scale distribution line, open-loop TVS, and a combination of procured and custom-fabricated cryogenic components were used in the cryogenic RCS build-up. Simulated on-orbit activation and thruster firing profiles were performed to quantify system heat gain and evaluate the TVS s capability to maintain the required propellant conditions at the inlet to the engine valves. Test data determined that a small control valve, such as a piezoelectric, is optimal to provide continuously the required thermal control. The data obtained from testing has also assisted with the development of fluid and thermal models of an RCS to refine integrated cryogenic propulsion system designs. This system allows a liquid oxygenbased main propulsion and reaction control system for a spacecraft, which improves performance, safety, and cost over conventional hypergolic systems due to higher performance, use of nontoxic propellants, potential for integration with life support and power subsystems, and compatibility with in-situ produced propellants.

  20. How does practise of internal Chinese martial arts influence postural reaction control?

    Science.gov (United States)

    Gorgy, Olivier; Vercher, Jean-Louis; Coyle, Thelma

    2008-04-01

    The aim of this study was to determine the effects of Chinese martial arts practice on postural reaction control after perturbation. Participants standing in Romberg tandem posture were subjected to an unexpected lateral platform translation with the eyes open or closed at two translation amplitudes. The peak displacement of the centre of pressure and of the centre of mass, and the onset latency of muscular activity (tibialis anterior, gastrocnemius, lumbodorsal muscular group, and rectus abdominis), were evaluated for martial arts practitioners and for sport and non-sport participants. Compared with the sport and non-sport participants, the martial arts group showed lower maximal centre of pressure and centre of mass peak displacements in both the lateral and anterior - posterior directions, but no difference was found in the onset of muscular responses. We conclude that martial arts practice influences postural reaction control during a fixed-support strategy in a tandem task. The martial arts group used the ankle joint more frequently than the sport and non-sport participants, especially in the eyes-closed conditions. Our results suggest that the better balance recovery in the martial arts group is a consequence of better control of biomechanical properties of the lower limbs (e.g. through muscular response by co-contraction), not a change in the neuromuscular temporal pattern.

  1. Waterhammer Modeling for the Ares I Upper Stage Reaction Control System Cold Flow Development Test Article

    Science.gov (United States)

    Williams, Jonathan H.

    2010-01-01

    The Upper Stage Reaction Control System provides three-axis attitude control for the Ares I launch vehicle during active Upper Stage flight. The system design must accommodate rapid thruster firing to maintain the proper launch trajectory and thus allow for the possibility to pulse multiple thrusters simultaneously. Rapid thruster valve closure creates an increase in static pressure, known as waterhammer, which propagates throughout the propellant system at pressures exceeding nominal design values. A series of development tests conducted in the fall of 2009 at Marshall Space Flight Center were performed using a water-flow test article to better understand fluid performance characteristics of the Upper Stage Reaction Control System. A subset of the tests examined waterhammer along with the subsequent pressure and frequency response in the flight-representative system and provided data to anchor numerical models. This thesis presents a comparison of waterhammer test results with numerical model and analytical results. An overview of the flight system, test article, modeling and analysis are also provided.

  2. Chemisorption on size-selected metal clusters: activation barriers and chemical reactions for deuterium and aluminum cluster ions

    International Nuclear Information System (INIS)

    Jarrold, M.F.; Bower, J.E.

    1988-01-01

    The authors describe a new approach to investigating chemisorption on size-selected metal clusters. This approach involves investigating the collision-energy dependence of chemisorption using low-energy ion beam techniques. The method provides a direct measure of the activation barrier for chemisorption and in some cases an estimate of the desorption energy as well. They describe the application of this technique to chemisorption of deuterium on size-selected aluminum clusters. The activation barriers increase with cluster size (from a little over 1 eV for Al 10 + to around 2 eV for Al 27 + ) and show significant odd-even oscillations. The activation barriers for the clusters with an odd number of atoms are larger than those for the even-numbered clusters. In addition to chemisorption of deuterium onto the clusters, chemical reactions were observed, often resulting in cluster fragmentation. The main products observed were Al/sub n-1/D + , Al/sub n-2/ + , and Al + for clusters with n + and Al/sub n-1/D + for the larger clusters

  3. Ground reaction force comparison of controlled resistance methods to isoinertial loading of the squat exercise - biomed 2010.

    Science.gov (United States)

    Paulus, David C; Reynolds, Michael C; Schilling, Brian K

    2010-01-01

    The ground reaction force during the concentric (raising) portion of the squat exercise was compared to that of isoinertial loading (free weights) for three pneumatically controlled resistance methods: constant resistance, cam force profile, and proportional force control based on velocity. Constant force control showed lower ground reaction forces than isoinertial loading throughout the range of motion (ROM). The cam force profile exhibited slightly greater ground reaction forces than isoinertial loading at 10 and 40% ROM with fifty-percent greater loading at 70% ROM. The proportional force control consistently elicited greater ground reaction force than isoinertial loading, which progressively ranged from twenty to forty percent increase over isoinertial loading except for being approximately equal at 85% ROM. Based on these preliminary results, the proportional control shows the most promise for providing loading that is comparable in magnitude to isoinertial loading. This technology could optimize resistance exercise for sport-specific training or as a countermeasure to atrophy during spaceflight.

  4. A Systems Approach towards an Intelligent and Self-Controlling Platform for Integrated Continuous Reaction Sequences**

    Science.gov (United States)

    Ingham, Richard J; Battilocchio, Claudio; Fitzpatrick, Daniel E; Sliwinski, Eric; Hawkins, Joel M; Ley, Steven V

    2015-01-01

    Performing reactions in flow can offer major advantages over batch methods. However, laboratory flow chemistry processes are currently often limited to single steps or short sequences due to the complexity involved with operating a multi-step process. Using new modular components for downstream processing, coupled with control technologies, more advanced multi-step flow sequences can be realized. These tools are applied to the synthesis of 2-aminoadamantane-2-carboxylic acid. A system comprising three chemistry steps and three workup steps was developed, having sufficient autonomy and self-regulation to be managed by a single operator. PMID:25377747

  5. Stability test and analysis of the Space Shuttle Primary Reaction Control Subsystem thruster

    Science.gov (United States)

    Applewhite, John; Hurlbert, Eric; Krohn, Douglas; Arndt, Scott; Clark, Robert

    1992-01-01

    The results are reported of a test program conducted on the Space Shuttle Primary Reaction Control Subsystem thruster in order to investigate the effects of trapped helium bubbles and saturated propellants on stability, determine if thruster-to-thruster stability variations are significant, and determine stability under STS-representative conditions. It is concluded that the thruster design is highly reliable in flight and that burn-through has not occurred. Significantly unstable thrusters are screened out, and wire wrap is found to protect against chamber burn-throughs and to provide a fail-safe thruster for this situation.

  6. [Social control in the Brazilian Unified Health System (SUS): discourse, action and reaction].

    Science.gov (United States)

    Oliveira, Ana Maria Caldeira; Ianni, Aurea Maria Zöllner; Dallari, Sueli Gandolfi

    2013-08-01

    This article seeks to describe and analyze the dynamics of social participation, from the standpoint of the social representations of the City Health Councillors of Belo Horizonte on the significance of social control. A methodological approach was used, backed by qualitative research techniques: semi-structured interviews and participant observation. Three years after the survey, documentary research was conducted to check for signs of institutional reaction seeking to minimize or even to overcome the difficulties reported. It was ascertained that the City Health Council political institution activated several mechanisms to improve their techniques of action and organization and also the commitment of stakeholders to this forum.

  7. Multi-scale modeling of diffusion-controlled reactions in polymers: renormalisation of reactivity parameters.

    Science.gov (United States)

    Everaers, Ralf; Rosa, Angelo

    2012-01-07

    The quantitative description of polymeric systems requires hierarchical modeling schemes, which bridge the gap between the atomic scale, relevant to chemical or biomolecular reactions, and the macromolecular scale, where the longest relaxation modes occur. Here, we use the formalism for diffusion-controlled reactions in polymers developed by Wilemski, Fixman, and Doi to discuss the renormalisation of the reactivity parameters in polymer models with varying spatial resolution. In particular, we show that the adjustments are independent of chain length. As a consequence, it is possible to match reactions times between descriptions with different resolution for relatively short reference chains and to use the coarse-grained model to make quantitative predictions for longer chains. We illustrate our results by a detailed discussion of the classical problem of chain cyclization in the Rouse model, which offers the simplest example of a multi-scale descriptions, if we consider differently discretized Rouse models for the same physical system. Moreover, we are able to explore different combinations of compact and non-compact diffusion in the local and large-scale dynamics by varying the embedding dimension.

  8. Influence of zeolite pore structure on product selectivities for protolysis and hydride transfer reactions in the cracking of n-pentane.

    Science.gov (United States)

    Miyaji, Akimitsu; Iwase, Yasuyoshi; Nishitoba, Toshiki; Long, Nguyen Quang; Motokura, Ken; Baba, Toshihide

    2015-02-21

    The conversion of n-pentane was carried out to examine the effects of reaction conditions on changes in product selectivities at 823 K, using zeolites with 10- and 12-membered rings. We also investigated the influence of the pore structure of these zeolites on their catalytic activities for both protolysis and hydride transfer reactions. In the first half of this work, we examined the influence of acidic proton concentration and n-pentane pressure on the reaction rates for protolysis and hydride transfer reactions using ZSM-5 zeolites. The rates of hydride transfer reactions were more influenced by pentane pressure compared to protolysis reactions, and were proportional to the square of n-pentane pressure and the concentration of acidic protons. In the second half of this work, the influence of the zeolite pore structure on changes in product selectivities with n-pentane conversion and that on the rates of protolysis and the hydride transfer reactions were revealed using various zeolites with 10- and 12-membered rings. The catalytic activities of zeolites for the protolysis and hydride transfer reactions were influenced more by the spatial volume of the zeolite cavity than the acid strength of protons on the zeolite.

  9. Influence of a photochemical reaction on the controlled potential coulometric determination of plutonium in a mixture with uranium

    International Nuclear Information System (INIS)

    Le Duigou, Y.; Leidert, W.

    1976-01-01

    Data are provided in support of a photochemical reaction which takes place simultaneously with the electrochemical reduction of quadrivalent plutonium during the controlled potential coulometric determination of plutonium in a mixture with uranium. The interfering effect of this reaction is overcome by placing the cell in a dark environment. (orig.) [de

  10. pH-Controlled Oxidation of an Aromatic Ketone: Structural Elucidation of the Products of Two Green Chemical Reactions

    Science.gov (United States)

    Ballard, C. Eric

    2010-01-01

    A laboratory experiment emphasizing the structural elucidation of organic compounds has been developed as a discovery exercise. The "unknown" compounds are the products of the pH-controlled oxidation of 4'-methoxyacetophenone with bleach. The chemoselectivity of this reaction is highly dependent on the pH of the reaction media: under basic…

  11. Measurements and calculations of 10B(n,He) reaction rates in a control rod in ZPPR

    International Nuclear Information System (INIS)

    Brumbach, S.B.; Collins, P.J.; Grasseschi, G.L.; Oliver, B.M.

    1986-01-01

    The helium accumulation fluence monitor (HAFM) technique has been used to measure the 10 B(n,He) reaction rate within B 4 C pellets in a control rod in ZPPR. Knowledge of this reaction rate is important to control rod design studies because helium production leads to control rod swelling, buildup of gas pressure and a reduction in thermal conductivity which can limit the lifetime of a control rod. We believe these to be the first measurements of boron capture within boron pins in a fast reactor spectrum. Previously reported measurements used 235 U foils to measure fission rates in a control rod, and to infer boron capture rates

  12. Controlled release of volatiles under mild reaction conditions: from nature to everyday products.

    Science.gov (United States)

    Herrmann, Andreas

    2007-01-01

    Volatile organic compounds serve in nature as semiochemicals for communication between species, and are often used as flavors and fragrances in our everyday life. The quite limited longevity of olfactive perception has led to the development of pro-perfumes or pro-fragrances--ideally nonvolatile and odorless fragrance precursors which release the active volatiles by bond cleavage. Only a limited amount of reaction conditions, such as hydrolysis, temperature changes, as well as the action of light, oxygen, enzymes, or microorganisms, can be used to liberate the many different chemical functionalities. This Review describes the controlled chemical release of fragrances and discusses additional challenges such as precursor stability during product storage as well as some aspects concerning toxicity and biodegradability. As the same systems can be applied in different areas of research, the scope of this Review covers fragrance delivery as well as the controlled release of volatiles in general.

  13. Synthetic Control of Kinetic Reaction Pathway and Cationic Ordering in High-Ni Layered Oxide Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dawei [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Kou, Ronghui [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Ren, Yang [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Sun, Cheng-Jun [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Zhao, Hu [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Zhang, Ming-Jian [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Li, Yan [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Huq, Ashifia [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Ko, J. Y. Peter [The Cornell High Energy Synchrotron Source, Cornell University, Ithaca NY 14853 USA; Pan, Feng [School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Sun, Yang-Kook [Department of Energy Engineering, Hanyang University, Seoul 133-791 South Korea; Yang, Yong [Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Bai, Jianming [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton NY 11973 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Wang, Feng [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA

    2017-08-25

    Nickel-rich layered transition metal oxides, LiNi1-x(MnCo)(x)O-2 (1-x >= 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7Mn0.15Co0.15O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.

  14. Experimental studies of water hammer in propellant feed system of reaction control system

    Directory of Open Access Journals (Sweden)

    Avanish Kumar

    2018-03-01

    Full Text Available Water hammer pressure transient produces large dynamic forces which can damage the pipes and other assemblies in the feed line of a reaction control system (RCS. It has led to the failure of pressure transducers monitoring the manifold pressure in the feed line of RCS. Therefore, water hammer studies have been carried out to understand its effect in feed line. Feedline system has been simplified to develop a mathematical model and experiments have been carried out at extensive levels. The mathematical model was developed considering pipe of uniform c/s and moving liquid-gas interface. The experimental studies have been done using water as working medium instead of actual propellant. The studies showed that rate of pressurization have a very critical role on the water hammer amplitude. Sensitivity studies have been also carried out to study the effect of density, friction and initial liquid column length on water hammer amplitude. Keywords: Water hammer, Reaction control system (RCS, Propellant feed system, Experimental study, Testing

  15. INDUSTRIAL BOILER RETROFIT FOR NOX CONTROL: COMBINED SELECTIVE NONCATALYTIC REDUCTION AND SELECTIVE CATALYTIC REDUCTION

    Science.gov (United States)

    The paper describes retrofitting and testing a 590 kW (2 MBtu/hr), oil-fired, three-pass, fire-tube package boiler with a combined selective noncatalytic reduction (SNCR) and selective catalytic reduction (SCR) system. The system demonstrated 85% nitrogen oxides (NOx) reduction w...

  16. Controlled growth of gold nanoparticles in zeolite L via ion-exchange reactions and thermal reduction processes

    KAUST Repository

    Zeng, Shangjing; Ding, Shuang; Li, Shangyu; Wang, Runwei; Zhang, Zongtao

    2014-01-01

    The growth of gold nanoparticles in zeolite can be controlled using ion-exchange reactions and thermal reduction processes. We produce a number of different sizes of the gold nanoparticles with the particle size increasing with increased temperature

  17. Aerodynamic Interactions of Propulsive Deceleration and Reaction Control System Jets on Mars-Entry Aeroshells

    Science.gov (United States)

    Alkandry, Hicham

    Future missions to Mars, including sample-return and human-exploration missions, may require alternative entry, descent, and landing technologies in order to perform pinpoint landing of heavy vehicles. Two such alternatives are propulsive deceleration (PD) and reaction control systems (RCS). PD can slow the vehicle during Mars atmospheric descent by directing thrusters into the incoming freestream. RCS can provide vehicle control and steering by inducing moments using thrusters on the hack of the entry capsule. The use of these PD and RCS jets, however, involves complex flow interactions that are still not well understood. The fluid interactions induced by PD and RCS jets for Mars-entry vehicles in hypersonic freestream conditions are investigated using computational fluid dynamics (CFD). The effects of central and peripheral PD configurations using both sonic and supersonic jets at various thrust conditions are examined in this dissertation. The RCS jet is directed either parallel or transverse to the freestream flow at different thrust conditions in order to examine the effects of the thruster orientation with respect to the center of gravity of the aeroshell. The physical accuracy of the computational method is also assessed by comparing the numerical results with available experimental data. The central PD configuration decreases the drag force acting on the entry capsule due to a shielding effect that prevents mass and momentum in the hypersonic freestream from reaching the aeroshell. The peripheral PD configuration also decreases the drag force by obstructing the flow around the aeroshell and creating low surface pressure regions downstream of the PD nozzles. The Mach number of the PD jets, however, does not have a significant effect on the induced fluid interactions. The reaction control system also alters the flowfield, surface, and aerodynamic properties of the aeroshell, while the jet orientation can have a significant effect on the control effectiveness

  18. Selection of GP. Mur antigen-negative RBC for blood recipients with anti-'Mia ' records decreases transfusion reaction rates in Taiwan.

    Science.gov (United States)

    Yang, C-A; Lin, J-A; Chang, C-W; Wu, K-H; Yeh, S-P; Ho, C-M; Chang, J-G

    2016-10-01

    To evaluate the clinical significance of GP. Mur antigen-negative blood selection for transfusion in patients with anti-'Mi a ' records. The GP. Mur RBC phenotype is prevalent (7·3%) in Taiwan. Antibodies against GP. Mur (anti-'Mi a ') are identified in 1·24% of our population, and anti-'Mi a ' screening using GP. Mur RBC has been routine for Taiwan's blood banks. However, due to the lack of commercial antibodies, only cross-matching was used to prevent transfusion of GP. Mur-positive blood to patients with anti-'Mi a ' in most hospitals. There is still a risk of GP. Mur-positive RBC exposure and subsequent anti-'Mi a '-related transfusion reactions. Since February 2014, GP. Mur antigen-negative RBCs identified by reaction with anti-'Mi a '-positive serum were selected for blood recipients with anti-'Mi a ' records. The transfusion reactions between January 2013 and January 2014 were compared with those that occurred between February 2014 and July 2015. The transfusion reaction rate was significantly higher in anti-'Mi a '-positive blood recipients compared to total subjects receiving an RBC transfusion before GP. Mur-negative donor RBC selection. After antigen-negative RBC selection, the transfusion reaction frequency in subjects with anti-'Mi a ' became similar to total blood recipients. IgG form anti-'Mi a ' antibodies were present in all cases of probable anti-'Mi a '-related transfusion reactions. The time required for anti-'Mi a ' boosting after transfusion was around 4-21 days. Selection of GP. Mur-negative RBC for transfusion to patients with anti-'Mi a ' records could decrease the rate of transfusion reaction and antibody boosting. This procedure should be incorporated into blood bank routines in areas where anti-'Mi a ' is prevalent. © 2016 British Blood Transfusion Society.

  19. Carrier-lifetime-controlled selective etching process for semiconductors using photochemical etching

    International Nuclear Information System (INIS)

    Ashby, C.I.H.; Myers, D.R.

    1992-01-01

    This patent describes a process for selectively photochemically etching a semiconductor material. It comprises introducing at least one impurity into at least one selected region of a semiconductor material to be etched to increase a local impurity concentration in the at least one selected region relative to an impurity concentration in regions of the semiconductor material adjacent thereto, for reducing minority carrier lifetimes within the at least one selected region relative to the adjacent regions for thereby providing a photochemical etch-inhibiting mask at the at least one selected region; and etching the semiconductor material by subjecting the surface of the semiconductor material to a carrier-driven photochemical etching reaction for selectively etching the regions of the semiconductor material adjacent the at least one selected region having the increase impurity concentration; wherein the step of introducing at least one impurity is performed so as not to produce damage to the at least one selected region before any etching is performed

  20. Vector control of wind turbine on the basis of the fuzzy selective neural net*

    Science.gov (United States)

    Engel, E. A.; Kovalev, I. V.; Engel, N. E.

    2016-04-01

    An article describes vector control of wind turbine based on fuzzy selective neural net. Based on the wind turbine system’s state, the fuzzy selective neural net tracks an maximum power point under random perturbations. Numerical simulations are accomplished to clarify the applicability and advantages of the proposed vector wind turbine’s control on the basis of the fuzzy selective neuronet. The simulation results show that the proposed intelligent control of wind turbine achieves real-time control speed and competitive performance, as compared to a classical control model with PID controllers based on traditional maximum torque control strategy.

  1. Review of Air Traffic Controller Selection: An International Perspective

    National Research Council Canada - National Science Library

    Broach, Dana

    1997-01-01

    ...) in Hamburg is reviewed. Job analysis, test battery development, and validation research for the controller occupation in the United Kingdom is presented next, followed by a description of the Swedish "MRU Project" on controller...

  2. Selected specific rates of reactions of transients from water in aqueous solution. Hydrated electron, supplemental data. [Reactions with transients from water, with inorganic solutes, and with solutes

    Energy Technology Data Exchange (ETDEWEB)

    Ross, A.B.

    1975-06-01

    A compilation of rates of reactions of hydrated electrons with other transients and with organic and inorganic solutes in aqueous solution appeared in NSRDS-NBS 43, and covered the literature up to early 1971. This supplement includes additional rates which have been published through July 1973.

  3. Evaluation of Selected Pre-Emergence Herbicides for Weed Control ...

    African Journals Online (AJOL)

    Pendimentalin had no significant effect on the plantlets across the rates tested. The best weed control was achieved with diuron applied at 25% and above, while the least weed control occurred on the control plot and these treated with 10% of atrazine and primextra Gold. However, there were no significant variations in the ...

  4. Study on Sensory Quality, Antioxidant Properties, and Maillard Reaction Products Formation in Rye-Buckwheat Cakes Enhanced with Selected Spices

    Directory of Open Access Journals (Sweden)

    Małgorzata Przygodzka

    2015-01-01

    Full Text Available The effect of selected spices included in the recipe of rye-buckwheat cakes on sensory quality, nutritional value, and Maillard reaction (MR products formation was addressed in this study. The cakes with cloves, nutmeg, allspice, cinnamon, vanilla, and spice mix addition revealed the highest overall quality values. Cakes enriched with cloves, allspice, and spice mix showed the highest rutin content and almost threefold higher available lysine contents whereas cakes enhanced with mix, cloves, and cinnamon were the richest source of phenolic compounds. The highest antioxidant capacity showed cakes with cloves and spice mix. The furosine, a marker of early stage of MR, was decreased in cakes with cloves, allspice, spice mix, and vanilla whereas fluorescent intermediatory compounds were reduced in cakes enhanced with cloves, allspice, and cinnamon. In contrast, browning index was increased as compared to cakes without spices. The FAST index was significantly lowered in all cakes enriched with spices, especially with cloves, allspice, and mix addition. The presence of cloves, allspice, and vanilla in cake formula was the most efficient in acrylamide strategy. It can be suggested that cloves, allspice, and vanilla might be used for production of safety and good quality cakes.

  5. Structural Evolution under Reaction Conditions of Supported (NH43HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

    Directory of Open Access Journals (Sweden)

    Fangli Jing

    2015-03-01

    Full Text Available When using heteropolycompounds in the selective oxidation of isobutane to methacrolein and methacrylic acid, both the keeping of the primary structure (Keggin units and the presence of acidic sites are necessary to obtain the desired products. The structural evolution of supported (NH43HPMo11VO40 (APMV catalysts under preliminary thermal oxidizing and reducing treatments was investigated. Various techniques, such as TGA/DTG (Thermo-Gravimetric Analysis/Derivative Thermo-Gravimetry, H2-TPR (Temperature Programed Reduction, in situ XRD (X-Ray Diffraction and XPS (X-ray Photoelectron Spectroscopy, were applied. It was clearly evidenced that the thermal stability and the reducibility of the Keggin units are improved by supporting 40% APMV active phase on Cs3PMo12O40 (CPM. The partial degradation of APMV takes place depending on temperature and reaction conditions. The decomposition of ammonium cations (releasing NH3 leads to the formation of vacancies favoring cationic exchanges between vanadium coming from the active phase and cesium coming from the support. In addition, the vanadium expelled from the Keggin structure is further reduced to V4+, species, which contributes (with Mo5+ to activate isobutane. The increase in reducibility of the supported catalyst is assumed to improve the catalytic performance in comparison with those of unsupported APMV.

  6. Spermatozoa of the shrew, Suncus murinus, undergo the acrosome reaction and then selectively kill cells in penetrating the cumulus oophorus.

    Science.gov (United States)

    Kaneko, T; Iida, H; Bedford, J M; Mōri, T

    2001-08-01

    In the musk shrew, Suncus murinus (and other shrews), the cumulus oophorus is ovulated as a discrete, compact, matrix-free ball of cells linked by specialized junctions. In examining how they penetrate the cumulus, Suncus spermatozoa were observed to first bind consistently by the ventral face over the acrosomal region to the exposed smooth surface of a peripheral cumulus cell. This was apparently followed by point fusions between the plasma and outer acrosomal membranes. Thereafter, spermatozoa without acrosomes were observed within cumulus cells that displayed signs of necrosis, as did some radially neighboring cumulus cells linked by zona adherens and gap junctions. Eventually, penetration of spermatozoa as far as the perizonal space around the zona pellucida left linear tracks of locally necrotic cells flanked by normal cumulus cells. Based on these and previous observations, we conclude that the acrosome reaction in Suncus is always induced by cumulus cells, and that reacted spermatozoa penetrate the cumulus by selective invasion and killing of cumulus cells along a linear track. Loss of the acrosome also exposes an apical body/perforatorium that is covered with barbs that appear to assist reacted fertilizing spermatozoa in binding to the zona pellucida. Because fertilized eggs displayed no other spermatozoa within or bound to the zona, an efficient block to polyspermy must prevent such binding of additional spermatozoa.

  7. Accurate Quantification of Cardiovascular Biomarkers in Serum Using Protein Standard Absolute Quantification (PSAQ™) and Selected Reaction Monitoring*

    Science.gov (United States)

    Huillet, Céline; Adrait, Annie; Lebert, Dorothée; Picard, Guillaume; Trauchessec, Mathieu; Louwagie, Mathilde; Dupuis, Alain; Hittinger, Luc; Ghaleh, Bijan; Le Corvoisier, Philippe; Jaquinod, Michel; Garin, Jérôme; Bruley, Christophe; Brun, Virginie

    2012-01-01

    Development of new biomarkers needs to be significantly accelerated to improve diagnostic, prognostic, and toxicity monitoring as well as therapeutic follow-up. Biomarker evaluation is the main bottleneck in this development process. Selected Reaction Monitoring (SRM) combined with stable isotope dilution has emerged as a promising option to speed this step, particularly because of its multiplexing capacities. However, analytical variabilities because of upstream sample handling or incomplete trypsin digestion still need to be resolved. In 2007, we developed the PSAQ™ method (Protein Standard Absolute Quantification), which uses full-length isotope-labeled protein standards to quantify target proteins. In the present study we used clinically validated cardiovascular biomarkers (LDH-B, CKMB, myoglobin, and troponin I) to demonstrate that the combination of PSAQ and SRM (PSAQ-SRM) allows highly accurate biomarker quantification in serum samples. A multiplex PSAQ-SRM assay was used to quantify these biomarkers in clinical samples from myocardial infarction patients. Good correlation between PSAQ-SRM and ELISA assay results was found and demonstrated the consistency between these analytical approaches. Thus, PSAQ-SRM has the capacity to improve both accuracy and reproducibility in protein analysis. This will be a major contribution to efficient biomarker development strategies. PMID:22080464

  8. Bifurcation analysis of a delay reaction-diffusion malware propagation model with feedback control

    Science.gov (United States)

    Zhu, Linhe; Zhao, Hongyong; Wang, Xiaoming

    2015-05-01

    With the rapid development of network information technology, information networks security has become a very critical issue in our work and daily life. This paper attempts to develop a delay reaction-diffusion model with a state feedback controller to describe the process of malware propagation in mobile wireless sensor networks (MWSNs). By analyzing the stability and Hopf bifurcation, we show that the state feedback method can successfully be used to control unstable steady states or periodic oscillations. Moreover, formulas for determining the properties of the bifurcating periodic oscillations are derived by applying the normal form method and center manifold theorem. Finally, we conduct extensive simulations on large-scale MWSNs to evaluate the proposed model. Numerical evidences show that the linear term of the controller is enough to delay the onset of the Hopf bifurcation and the properties of the bifurcation can be regulated to achieve some desirable behaviors by choosing the appropriate higher terms of the controller. Furthermore, we obtain that the spatial-temporal dynamic characteristics of malware propagation are closely related to the rate constant for nodes leaving the infective class for recovered class and the mobile behavior of nodes.

  9. Independent control of the shape and composition of ionic nanocrystals through sequential cation exchange reactions

    Energy Technology Data Exchange (ETDEWEB)

    Luther, Joseph Matthew; Zheng, Haimei; Sadtler, Bryce; Alivisatos, A. Paul

    2009-07-06

    Size- and shape-controlled nanocrystal growth is intensely researched for applications including electro-optic, catalytic, and medical devices. Chemical transformations such as cation exchange overcome the limitation of traditional colloidal synthesis, where the nanocrystal shape often reflects the inherent symmetry of the underlying lattice. Here we show that nanocrystals, with established synthetic protocols for high monodispersity, can be templates for independent composition control. Specifically, controlled interconversion between wurtzite CdS, chalcocite Cu2S, and rock salt PbS occurs while preserving the anisotropic dimensions unique to the as-synthesized materials. Sequential exchange reactions between the three sulfide compositions are driven by the disparate solubilites of the metal ion exchange pair in specific coordinating molecules. Starting with CdS, highly anisotropic PbS nanorods are created, which serve as an important material for studying strong 2-dimensional quantum confinement, as well as for optoelectronic applications. Furthermore, interesting nanoheterostructures of CdS|PbS are obtained by precise control over ion insertion and removal.

  10. Control configuration selection for bilinear systems via generalised Hankel interaction index array

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Tahavori, Maryamsadat

    2015-01-01

    configuration selection. It is well known that a suitable control configuration selection is an important prerequisite for a successful industrial control. In this paper the problem of control configuration selection for multiple-input and multiple-output (MIMO) bilinear processes is addressed. First...... way, an iterative method for solving the generalised Sylvester equation is proposed. The generalised cross-gramian is used to form the generalised Hankel interaction index array. The generalised Hankel interaction index array is used for control configuration selection of MIMO bilinear processes. Most......Decentralised and partially decentralised control strategies are very popular in practice. To come up with a suitable decentralised or partially decentralised control structure, it is important to select the appropriate input and output pairs for control design. This procedure is called control...

  11. Thermodynamic and molecular origin of interfacial rate enhancements and endo-selectivities of a Diels-Alder reaction.

    Science.gov (United States)

    Beniwal, Vijay; Kumar, Anil

    2017-02-08

    Organic reactions in general display large rate accelerations when performed under interfacial conditions, such as on water or at ionic liquid interfaces. However, a clear picture of the physicochemical factors responsible for this large rate enhancements is not available. To gain an understanding of the thermodynamic and molecular origin of these large rate enhancements, we performed a Diels-Alder reaction between cyclopentadiene and methyl acrylate at ionic liquid/n-hexane interfaces. This study describes, for the first time, a methodology for the calculation of the activation parameters of an interfacial reaction. It has been seen that the energy of activation for an interfacial reaction is much smaller than that of the corresponding homogeneous reaction, resulting into the large rate acceleration for the interfacial reaction. Furthermore, the study describes the effects of the alkyl chain length of ionic liquid cations, the extent of heterogeneity, and the polarity of ionic liquids on the rate constants and stereoselectivity of the reaction.

  12. Selection of References in Wind Turbine Model Predictive Control Design

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Hovgaard, Tobias

    2015-01-01

    a model predictive controller for a wind turbine. One of the important aspects for a tracking control problem is how to setup the optimal reference tracking problem, as it might be relevant to track, e.g., the three concurrent references: optimal pitch angle, optimal rotational speed, and optimal power......Lowering the cost of energy is one of the major focus areas in the wind turbine industry. Recent research has indicated that wind turbine controllers based on model predictive control methods can be useful in obtaining this objective. A number of design considerations have to be made when designing....... The importance if the individual references differ depending in particular on the wind speed. In this paper we investigate the performance of a reference tracking model predictive controller with two different setups of the used optimal reference signals. The controllers are evaluated using an industrial high...

  13. Selecting Optimal Control Portfolios to Improve Army Aviation Safety

    National Research Council Canada - National Science Library

    Shelton, Sarah

    2001-01-01

    .... The Safety Center chartered the Aviation Safety Investment Strategy Team to evaluate accidents to determine their hazards, or contributing conditions, and their controls, or reduction measures...

  14. Supramolecular recognition control of polyethylene glycol modified N-doped graphene quantum dots: tunable selectivity for alkali and alkaline-earth metal ions.

    Science.gov (United States)

    Yang, Siwei; Sun, Jing; Zhu, Chong; He, Peng; Peng, Zheng; Ding, Guqiao

    2016-02-07

    The graphene quantum dot based fluorescent probe community needs unambiguous evidence about the control on the ion selectivity. In this paper, polyethylene glycol modified N-doped graphene quantum dots (PN-GQDs) were synthesized by alkylation reaction between graphene quantum dots and organic halides. We demonstrate the tunable selectivity and sensitivity by controlling the supramolecular recognition through the length and the end group size of the polyether chain on PN-GQDs. The relationship formulae between the selectivity/detection limit and polyether chains are experimentally deduced. The polyether chain length determines the interaction between the PN-GQDs and ions with different ratios of charge to radius, which in turn leads to a good selectivity control. Meanwhile the detection limit shows an exponential growth with the size of end groups of the polyether chain. The PN-GQDs can be used as ultrasensitive and selective fluorescent probes for Li(+), Na(+), K(+), Mg(2+), Ca(2+) and Sr(2+), respectively.

  15. The Enhancement of the Selectivity of Complex Reactions by a Catalytic Membrane Reactor -Ethylene Oxidation Over a Ag Catalyst Supported in a Ceramic Membrane-

    OpenAIRE

    馮, 臨; 小林, 正義; Lin, FENG; Masayoshi, KOBAYASHI

    1991-01-01

    This research demonstrated that, using a membrane reactor consisting of a tubular, microporous, glass-ceramic membrane, it is possible to achieve selective oxidation of ethylene to ethylene oxide with an Ag catalyst. In experiments which a reaction temperature range of 115 to 300℃ and a contact time of 1.5 to 5 seconds, resulting data illustrated the following characteristics of this membrane reactor : 1) compared with a classic tubular reactor, the selectivity of ethylene oxide is increased ...

  16. Test Results for a Non-toxic, Dual Thrust Reaction Control Engine

    Science.gov (United States)

    Robinson, Philip J.; Veith, Eric M.; Turpin, Alicia A.

    2005-01-01

    A non-toxic, dual thrust reaction control engine (RCE) was successfully tested over a broad range of operating conditions at the Aerojet Sacramento facility. The RCE utilized LOX/Ethanol propellants; and was tested in steady state and pulsing modes at 25-lbf thrust (vernier) and at 870-lbf thrust (primary). Steady state vernier tests vaned chamber pressure (Pc) from 0.78 to 5.96 psia, and mixture ratio (MR) from 0.73 to 1.82, while primary steady state tests vaned Pc from 103 to 179 psia and MR from 1.33 to 1.76. Pulsing tests explored EPW from 0.080 to 10 seconds and DC from 5 to 50 percent at both thrust levels. Vernier testing accumulated a total of 6,670 seconds of firing time, and 7,215 pulses, and primary testing accumulated a total of 2,060 seconds of firing time and 3,646 pulses.

  17. A Reaction-Diffusion-Based Coding Rate Control Mechanism for Camera Sensor Networks

    Directory of Open Access Journals (Sweden)

    Naoki Wakamiya

    2010-08-01

    Full Text Available A wireless camera sensor network is useful for surveillance and monitoring for its visibility and easy deployment. However, it suffers from the limited capacity of wireless communication and a network is easily overflown with a considerable amount of video traffic. In this paper, we propose an autonomous video coding rate control mechanism where each camera sensor node can autonomously determine its coding rate in accordance with the location and velocity of target objects. For this purpose, we adopted a biological model, i.e., reaction-diffusion model, inspired by the similarity of biological spatial patterns and the spatial distribution of video coding rate. Through simulation and practical experiments, we verify the effectiveness of our proposal.

  18. A reaction-diffusion-based coding rate control mechanism for camera sensor networks.

    Science.gov (United States)

    Yamamoto, Hiroshi; Hyodo, Katsuya; Wakamiya, Naoki; Murata, Masayuki

    2010-01-01

    A wireless camera sensor network is useful for surveillance and monitoring for its visibility and easy deployment. However, it suffers from the limited capacity of wireless communication and a network is easily overflown with a considerable amount of video traffic. In this paper, we propose an autonomous video coding rate control mechanism where each camera sensor node can autonomously determine its coding rate in accordance with the location and velocity of target objects. For this purpose, we adopted a biological model, i.e., reaction-diffusion model, inspired by the similarity of biological spatial patterns and the spatial distribution of video coding rate. Through simulation and practical experiments, we verify the effectiveness of our proposal.

  19. Prevention, development, and control of psychophysical false reactions in cases of imminent or existing catastrophes

    International Nuclear Information System (INIS)

    Brickenstein, R.

    1981-01-01

    If a random group of people or a solid community feel threatened in their economical, ideologic-religious, or physical existences, individual reactions which occur frequently, such as pathologically increased fear, dread can become new common symptoms, the so-called summation phenomenous. Especially general uneasiness, emotional conditions indicating crises and tendency to panic belong to these symptoms. In a mass of people, all preconditions of the development of a panic are existing. This can be acute in the abortive form, but also chronic. Measures of preventing or controlling a panic can be successful only if they take into consideration the genesis and the art of the different sorts of panic. Therefore, it is urgently necessary for any organisatory or political or military leader to know these in order to be able to prevent a catastrophe. (orig.) [de

  20. A Tool Measuring Remaining Thickness of Notched Acoustic Cavities in Primary Reaction Control Thruster NDI Standards

    Science.gov (United States)

    Sun, Yushi; Sun, Changhong; Zhu, Harry; Wincheski, Buzz

    2006-01-01

    Stress corrosion cracking in the relief radius area of a space shuttle primary reaction control thruster is an issue of concern. The current approach for monitoring of potential crack growth is nondestructive inspection (NDI) of remaining thickness (RT) to the acoustic cavities using an eddy current or remote field eddy current probe. EDM manufacturers have difficulty in providing accurate RT calibration standards. Significant error in the RT values of NDI calibration standards could lead to a mistaken judgment of cracking condition of a thruster under inspection. A tool based on eddy current principle has been developed to measure the RT at each acoustic cavity of a calibration standard in order to validate that the standard meets the sample design criteria.

  1. The Neural Basis of Cognitive Control: Response Selection and Inhibition

    Science.gov (United States)

    Goghari, Vina M.; MacDonald, Angus W., III

    2009-01-01

    The functional neuroanatomy of tasks that recruit different forms of response selection and inhibition has to our knowledge, never been directly addressed in a single fMRI study using similar stimulus-response paradigms where differences between scanning time and sequence, stimuli, and experimenter instructions were minimized. Twelve right-handed…

  2. Study of the selective abstration reaction of the hydrogen atom in the radiolysis and photolysis of alkane mixture at 77 K

    International Nuclear Information System (INIS)

    Guedes, S.M.L.

    1979-01-01

    The occurence of the selective abstraction reaction of the solute hydrogen atom by hydrogen atom produced during radiolysis or photolysis of the systems such as neopentane/cyclo-hexane/HI, neopentane/2,3 dimethylbutane, n-pentane/HI/cyclo-hexane and cyclo-hexane/HI/n-pentane, at 77 K is studied. Experiments have been undertaken on the kinetics nature of the active species, the H atom, during radiolysis and photolysis of the neopentane/cyclo-hexane/HI system at 77 K, presenting competitive reactions. Studies have also been made on the occurrence of the selective abstraction reaction in inverted systems, in which the concentrations of the components of a system are so much altered that the solute becomes the solvent and vice-versa, in the other system. By means of photolysis at 77 K, it has been observed that for the two systems constitued by the cyclo-hexane and n-pentane the selective abstraction reaction occurs. However, for radiolysis of that same two systems it has been observed that only the hydrogen atom abstraction reaction corresponding to the solvent occurs. (Author) [pt

  3. Exploring Tyrosine-Triazolinedione (TAD) Reactions for the Selective Conjugation and Cross-Linking of N-Carboxyanhydride (NCA) Derived Synthetic Copolypeptides.

    Science.gov (United States)

    Hanay, Saltuk B; Ritzen, Bas; Brougham, Dermot; Dias, Aylvin A; Heise, Andreas

    2017-07-01

    Highly efficient functionalization and cross-linking of polypeptides is achieved via tyrosine-triazolinedione (TAD) conjugation chemistry. The feasibility of the reaction is demonstrated by the reaction of 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) with tyrosine containing block copolymer poly(ethylene glycol)-Tyr 4 as well as a statistical copolymer of tyrosine and lysine (poly(Lys 40 -st-Tyr 10 )) prepared form N-carboxyanhydride polymerization. Selective reaction of PTAD with the tyrosine units is obtained and verified by size exclusion chromatography and NMR spectroscopy. Moreover, two monofunctional and two difunctional TAD molecules are synthesized. It is found that their stability in the aqueous reaction media significantly varied. Under optimized reaction conditions selective functionalization and cross-linking, yielding polypeptide hydrogels, can be achieved. TAD-mediated conjugation can offer an interesting addition in the toolbox of selective (click-like) polypeptide conjugation methodologies as it does not require functional non-natural amino acids. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Reduced-graphene-oxide supported tantalum-based electrocatalysts: Controlled nitrogen doping and oxygen reduction reaction

    Science.gov (United States)

    Yang, Xiaoyun; Mo, Qijie; Guo, Yulin; Chen, Nana; Gao, Qingsheng

    2018-03-01

    Controlled N-doping is feasible to engineer the surface stoichiometry and the electronic configuration of metal-oxide electrocatalysts toward efficient oxygen reduction reactions (ORR). Taking reduced graphene oxide supported tantalum-oxides (TaOx/RGO) for example, this work illustrated the controlled N-doping in both metal-oxides and carbon supports, and the contribution to the improved ORR activity. The active N-doped TaOx/RGO electrocatalysts were fabricated via SiO2-assisted pyrolysis, in which the amount and kind of N-doping were tailored toward efficient electrocatalysis. The optimal nanocomposites showed a quite positive half-wave potential (0.80 V vs. RHE), the excellent long-term stability, and the outstanding tolerance to methanol crossing. The improvement in ORR was reasonably attributed to the synergy between N-doped TaOx and N-doped RGO. Elucidating the importance of controlled N-doping for electrocatalysis, this work will open up new opportunities to explore noble-metal-free materials for renewable energy applications.

  5. Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

    Science.gov (United States)

    Waller, Jess; Saulsberry, Regor L.

    2003-01-01

    Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

  6. Optimal control of an invasive species using a reaction-diffusion model and linear programming

    Science.gov (United States)

    Bonneau, Mathieu; Johnson, Fred A.; Smith, Brian J.; Romagosa, Christina M.; Martin, Julien; Mazzotti, Frank J.

    2017-01-01

    Managing an invasive species is particularly challenging as little is generally known about the species’ biological characteristics in its new habitat. In practice, removal of individuals often starts before the species is studied to provide the information that will later improve control. Therefore, the locations and the amount of control have to be determined in the face of great uncertainty about the species characteristics and with a limited amount of resources. We propose framing spatial control as a linear programming optimization problem. This formulation, paired with a discrete reaction-diffusion model, permits calculation of an optimal control strategy that minimizes the remaining number of invaders for a fixed cost or that minimizes the control cost for containment or protecting specific areas from invasion. We propose computing the optimal strategy for a range of possible model parameters, representing current uncertainty on the possible invasion scenarios. Then, a best strategy can be identified depending on the risk attitude of the decision-maker. We use this framework to study the spatial control of the Argentine black and white tegus (Salvator merianae) in South Florida. There is uncertainty about tegu demography and we considered several combinations of model parameters, exhibiting various dynamics of invasion. For a fixed one-year budget, we show that the risk-averse strategy, which optimizes the worst-case scenario of tegus’ dynamics, and the risk-neutral strategy, which optimizes the expected scenario, both concentrated control close to the point of introduction. A risk-seeking strategy, which optimizes the best-case scenario, focuses more on models where eradication of the species in a cell is possible and consists of spreading control as much as possible. For the establishment of a containment area, assuming an exponential growth we show that with current control methods it might not be possible to implement such a strategy for some of the

  7. Frequency Adaptive Selective Harmonic Control for Grid-Connected Inverters

    DEFF Research Database (Denmark)

    Yang, Yongheng; Zhou, Keliang; Wang, Huai

    2015-01-01

    SHC scheme consists of multiple parallel recursive (nk±m)-order (k = 0, 1, 2, . . ., and m ≤ n/2) harmonic control modules with independent control gains, which can be optimally weighted in accordance with the harmonic distribution. The hybrid SHC thus offers an optimal trade-off among cost...

  8. Dynamics and Control of Chemical Reactors-Selectively Surveyed

    DEFF Research Database (Denmark)

    Jørgensen, S. B.; Jensen, N.

    1989-01-01

    The chemical reactor or bioreactor is physically at a central position in a process, and often with a decisive role on the overall technical and economical performance. Even though application of feedback control on reactors is gaining momentum and on-line optimization has been implemented....... For bioreactors the theory and practice of reactor design, dynamics and control have to be adapted to the peculiarities of the biological catalysts. Enzymes, the protein catalysts, are the simplest ones, which have many common features with chemical catalysts. The living cells are much more complex, these growing...... in industry, many reactor control problems are still left unsolved or only partly solved using open loop strategies where disturbance rejection and model inaccuracies have to be handled through manual reactor control and feedback control of raw material preprocessing and product purification operations...

  9. Response to selection under controlled environment versus natural selection in diverse regions across Canada

    Science.gov (United States)

    Red clover is a widely adaptable and productive forage legume species found in most temperate regions of the world. To date, specific selection techniques for identifying genotypes with superior persistence have not been successful in improving the general adaptation and the long-term persistence o...

  10. Rationalization of Product Selectivities in Asymmetric Horner-Wadsworth-Emmons Reactions by Use of a New Method for Transition-State Modeling

    DEFF Research Database (Denmark)

    Norrby, Per-Ola; Brandt, Peter; Rein, Tobias

    1999-01-01

    A new method for creating a transition-state force field, based on quantum chemical normal-mode analysis, is described. The force field was used to rationalize the experimentally observed product selectivities in asymmetric Horner-Wadsworth-Emmons reactions between some chiral phosphonates and ch...

  11. Palladium-catalyzed aerobic regio- and stereo-selective olefination reactions of phenols and acrylates via direct dehydrogenative C(sp2)-O cross-coupling.

    Science.gov (United States)

    Wu, Yun-Bin; Xie, Dan; Zang, Zhong-Lin; Zhou, Cheng-He; Cai, Gui-Xin

    2018-04-26

    An efficient olefination protocol for the oxidative dehydrogenation of phenols and acrylates has been achieved using a palladium catalyst and O2 as the sole oxidant. This reaction exhibits high regio- and stereo-selectivity (E-isomers) with moderate to excellent isolated yields and a wide substrate scope (32 examples) including ethyl vinyl ketone and endofolliculina.

  12. Hydrogen-bond-driven electrophilic activation for selectivity control: scope and limitations of fluorous alcohol-promoted selective formation of 1,2-disubstituted benzimidazoles and mechanistic insight for rationale of selectivity.

    Science.gov (United States)

    Chebolu, Rajesh; Kommi, Damodara N; Kumar, Dinesh; Bollineni, Narendra; Chakraborti, Asit K

    2012-11-16

    Hydrogen-bond-driven electrophilic activation for selectivity control during competitive formation of 1,2-disubstituted and 2-substituted benzimidazoles from o-phenylenediamine and aldehydes is reported. The fluorous alcohols trifluoroethanol and hexafluoro-2-propanol efficiently promote the cyclocondensation of o-phenylenediamine with aldehydes to afford selectively the 1,2-disubstituted benzimidazoles at rt in short times. A mechanistic insight is invoked by NMR, mass spectrometry, and chemical studies to rationalize the selectivity. The ability of the fluorous alcohols in promoting the reaction and controlling the selectivity can be envisaged from their better hydrogen bond donor (HBD) abilities compared to that of the other organic solvents as well as of water. Due to the better HBD values, the fluorous alcohols efficiently promote the initial bisimine formation by electrophilic activation of the aldehyde carbonyl. Subsequently the hydrogen-bond-mediated activation of the in situ-formed bisimine triggers the rearrangement via 1,3-hydride shift to form the 1,2-disubstituted benzimidazoles.

  13. Neural effects of cognitive control load on auditory selective attention.

    Science.gov (United States)

    Sabri, Merav; Humphries, Colin; Verber, Matthew; Liebenthal, Einat; Binder, Jeffrey R; Mangalathu, Jain; Desai, Anjali

    2014-08-01

    Whether and how working memory disrupts or alters auditory selective attention is unclear. We compared simultaneous event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) responses associated with task-irrelevant sounds across high and low working memory load in a dichotic-listening paradigm. Participants performed n-back tasks (1-back, 2-back) in one ear (Attend ear) while ignoring task-irrelevant speech sounds in the other ear (Ignore ear). The effects of working memory load on selective attention were observed at 130-210ms, with higher load resulting in greater irrelevant syllable-related activation in localizer-defined regions in auditory cortex. The interaction between memory load and presence of irrelevant information revealed stronger activations primarily in frontal and parietal areas due to presence of irrelevant information in the higher memory load. Joint independent component analysis of ERP and fMRI data revealed that the ERP component in the N1 time-range is associated with activity in superior temporal gyrus and medial prefrontal cortex. These results demonstrate a dynamic relationship between working memory load and auditory selective attention, in agreement with the load model of attention and the idea of common neural resources for memory and attention. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Road Network Selection Based on Road Hierarchical Structure Control

    Directory of Open Access Journals (Sweden)

    HE Haiwei

    2015-04-01

    Full Text Available A new road network selection method based on hierarchical structure is studied. Firstly, road network is built as strokes which are then classified into hierarchical collections according to the criteria of betweenness centrality value (BC value. Secondly, the hierarchical structure of the strokes is enhanced using structural characteristic identification technique. Thirdly, the importance calculation model was established according to the relationships among the hierarchical structure of the strokes. Finally, the importance values of strokes are got supported with the model's hierarchical calculation, and with which the road network is selected. Tests are done to verify the advantage of this method by comparing it with other common stroke-oriented methods using three kinds of typical road network data. Comparision of the results show that this method had few need to semantic data, and could eliminate the negative influence of edge strokes caused by the criteria of BC value well. So, it is better to maintain the global hierarchical structure of road network, and suitable to meet with the selection of various kinds of road network at the same time.

  15. ATAQS: A computational software tool for high throughput transition optimization and validation for selected reaction monitoring mass spectrometry

    Directory of Open Access Journals (Sweden)

    Ramos Hector

    2011-03-01

    Full Text Available Abstract Background Since its inception, proteomics has essentially operated in a discovery mode with the goal of identifying and quantifying the maximal number of proteins in a sample. Increasingly, proteomic measurements are also supporting hypothesis-driven studies, in which a predetermined set of proteins is consistently detected and quantified in multiple samples. Selected reaction monitoring (SRM is a targeted mass spectrometric technique that supports the detection and quantification of specific proteins in complex samples at high sensitivity and reproducibility. Here, we describe ATAQS, an integrated software platform that supports all stages of targeted, SRM-based proteomics experiments including target selection, transition optimization and post acquisition data analysis. This software will significantly facilitate the use of targeted proteomic techniques and contribute to the generation of highly sensitive, reproducible and complete datasets that are particularly critical for the discovery and validation of targets in hypothesis-driven studies in systems biology. Result We introduce a new open source software pipeline, ATAQS (Automated and Targeted Analysis with Quantitative SRM, which consists of a number of modules that collectively support the SRM assay development workflow for targeted proteomic experiments (project management and generation of protein, peptide and transitions and the validation of peptide detection by SRM. ATAQS provides a flexible pipeline for end-users by allowing the workflow to start or end at any point of the pipeline, and for computational biologists, by enabling the easy extension of java algorithm classes for their own algorithm plug-in or connection via an external web site. This integrated system supports all steps in a SRM-based experiment and provides a user-friendly GUI that can be run by any operating system that allows the installation of the Mozilla Firefox web browser. Conclusions Targeted

  16. In situ Raman scattering study on a controllable plasmon-driven surface catalysis reaction on Ag nanoparticle arrays

    International Nuclear Information System (INIS)

    Dai, Z G; Xiao, X H; Zhang, Y P; Ren, F; Wu, W; Zhang, S F; Zhou, J; Jiang, C Z; Mei, F

    2012-01-01

    Control of the plasmon-driven chemical reaction for the transformation of 4-nitrobenzenethiol to p,p′-dimercaptoazobenzene by Ag nanoparticle arrays was studied. The Ag nanoparticle arrays were fabricated by means of nanosphere lithography. By changing the PS particle size, the localized surface plasmon resonance (LSPR) peaks of the Ag nanoparticle arrays can be tailored from 460 to 560 nm. The controlled reaction process was monitored by in situ surface-enhanced Raman scattering. The reaction can be dramatically influenced by varying the duration of laser exposure, Ag nanoparticle size, laser power and laser excitation wavelength. The maximum reaction speed was achieved when the LSPR wavelength of the Ag nanoparticle arrays matched the laser excitation wavelength. The experimental results reveal that the strong LSPR can effectively drive the transfer of the ‘hot’ electrons that decay from the plasmon to the reactants. The experimental results were confirmed by theoretical calculations. (paper)

  17. Classical Example of Total Kinetic and Thermodynamic Control: The Diels-Alder Reaction between DMAD and Bis-furyl Dienes.

    Science.gov (United States)

    Borisova, Kseniya K; Kvyatkovskaya, Elizaveta A; Nikitina, Eugeniya V; Aysin, Rinat R; Novikov, Roman A; Zubkov, Fedor I

    2018-04-20

    A rare example of chemospecificity in the tandem Diels-Alder reaction of activated alkynes and bis-dienes has been revealed. The reaction between bis-furyl dienes and DMAD occurs at 25-80 °C and leads to kinetically controlled "pincer" adducts, 4a,8a-disubstituted 1,4:5,8-diepoxynaphthalenes. On the contrary, only thermodynamically controlled "domino" adducts (2,3-disubstituted 1,4:5,8-diepoxynaphthalenes) are formed in the same reaction at 140 °C. The "pincer" adducts can be transformed to the "domino" adducts at heating. The rate constants for reactions of both types were calculated using dynamic 1 H NMR spectroscopy.

  18. Electromyographic control of functional electrical stimulation in selected patients.

    Science.gov (United States)

    Graupe, D; Kohn, K H; Basseas, S; Naccarato, E

    1984-07-01

    The paper describes initial results of above-lesion electromyographic (EMG) controlled functional electrical stimulation (FES) of paraplegics. Such controlled stimulation is to provide upper-motor-neuron paraplegics (T5 to T12) with self-controlled standing and some walking without braces and with only the help of walkers or crutches. The above-lesion EMG signal employed serves to map the posture of the patient's upper trunk via a computerized mapping of the temporal patterns of that EMG. Such control also has an inherent safety feature in that it prevents the patient from performing a lower-limb movement via FES unless his trunk posture is adequate. Copyright 2013, SLACK Incorporated.

  19. Digest of impaired driving and selected beverage control laws

    Science.gov (United States)

    2006-04-01

    This digest reports the status of State laws that are concerned with impaired driving offenses and alcoholic beverage control. Unless otherwise indicated, the status of the laws reported is January 1, 2006.

  20. The lack of selection bias in a snowball sampled case-control study on drug abuse.

    Science.gov (United States)

    Lopes, C S; Rodrigues, L C; Sichieri, R

    1996-12-01

    Friend controls in matched case-control studies can be a potential source of bias based on the assumption that friends are more likely to share exposure factors. This study evaluates the role of selection bias in a case-control study that used the snowball sampling method based on friendship for the selection of cases and controls. The cases selected fro the study were drug abusers located in the community. Exposure was defined by the presence of at least one psychiatric diagnosis. Psychiatric and drug abuse/dependence diagnoses were made according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria. Cases and controls were matched on sex, age and friendship. The measurement of selection bias was made through the comparison of the proportion of exposed controls selected by exposed cases (p1) with the proportion of exposed controls selected by unexposed cases (p2). If p1 = p2 then, selection bias should not occur. The observed distribution of the 185 matched pairs having at least one psychiatric disorder showed a p1 value of 0.52 and a p2 value of 0.51, indicating no selection bias in this study. Our findings support the idea that the use of friend controls can produce a valid basis for a case-control study.

  1. Switching in the Cocktail Party: Exploring Intentional Control of Auditory Selective Attention

    Science.gov (United States)

    Koch, Iring; Lawo, Vera; Fels, Janina; Vorlander, Michael

    2011-01-01

    Using a novel variant of dichotic selective listening, we examined the control of auditory selective attention. In our task, subjects had to respond selectively to one of two simultaneously presented auditory stimuli (number words), always spoken by a female and a male speaker, by performing a numerical size categorization. The gender of the…

  2. Combining epidemiology and biomechanics in sports injury prevention research: a new approach for selecting suitable controls.

    Science.gov (United States)

    Finch, Caroline F; Ullah, Shahid; McIntosh, Andrew S

    2011-01-01

    Several important methodological issues need to be considered when designing sports injury case-control studies. Major design goals for case-control studies include the accounting for prior injury risk exposure, and optimal definitions of both cases and suitable controls are needed to ensure this. This article reviews methodological aspects of published sports injury case-control studies, particularly with regard to the selection of controls. It argues for a new approach towards selecting controls for case-control studies that draws on an interface between epidemiological and biomechanical concepts. A review was conducted to identify sport injury case-control studies published in the peer-review literature during 1985-2008. Overall, 32 articles were identified, of which the majority related to upper or lower extremity injuries. Matching considerations were used for control selection in 16 studies. Specific mention of application of biomechanical principles in the selection of appropriate controls was absent from all studies, including those purporting to evaluate the benefits of personal protective equipment to protect against impact injury. This is a problem because it could lead to biased conclusions, as cases and controls are not fully comparable in terms of similar biomechanical impact profiles relating to the injury incident, such as site of the impact on the body. The strength of the conclusions drawn from case-control studies, and the extent to which results can be generalized, is directly influenced by the definition and recruitment of cases and appropriate controls. Future studies should consider the interface between epidemiological and biomechanical concepts when choosing appropriate controls to ensure that proper adjustment of prior exposure to injury risk is made. To provide necessary guidance for the optimal selection of controls in case-control studies of interventions to prevent sports-related impact injury, this review outlines a new case-control

  3. Scalable preparation of sized-controlled Co-N-C electrocatalyst for efficient oxygen reduction reaction

    Science.gov (United States)

    Ai, Kelong; Li, Zelun; Cui, Xiaoqiang

    2017-11-01

    Heat-treated metal-nitrogen-carbon (M-N-C) materials are emerging as promising non-precious catalysts to replace expensive Pt-based materials for oxygen reduction reaction (ORR) in energy conversion and storage devices. Despite recent progress, their activity and durability are still far from satisfactory. The activity site and particle size are among the most important factors for the ORR activity of M-N-C catalysts. Extensive efforts have been made to reveal the correlation of active site and activity. However, it remains unclear to what extent the particle size will influence the ORR activity of M-N-C materials. Moreover, to the best of our knowledge, controllable synthesis of M-N-C catalysts with high-density activity sites remains elusive. Herein, we develop a straightforward method to produce a monodisperse and size-controlled Co-N-C (Nano-P-ZIF-67) electrocatalyst, and systemically investigate its catalytic mechanisms. Only by optimizing the particle size, Nano-P-ZIF-67 outperforms the commercial 20 wt% Pt/C regarding all evaluating indicators for ORR catalysts in alkaline media including higher catalytic activity, durability, and stronger methanol tolerance. Nano-P-ZIF-67 is assembled into a cell, and the cell shows a power density of 45.5 mW/cm2, which is the highest value among currently studied cathode catalysts. We expect Nano-P-ZIF-67 to be a highly interesting candidate for the next generation of ORR catalysts.

  4. Summary of Altitude Pulse Testing of a 100-lbf L02/LCH4 Reaction Control Engine

    Science.gov (United States)

    Marshall, William M.; Kleinhenz, Julie E.

    2011-01-01

    Recently, liquid oxygen-liquid methane (LO2/LCH4) has been considered as a potential "green" propellant alternative for future exploration missions. The Propulsion and Cryogenic Advanced Development (PCAD) project has been tasked by NASA to develop this propulsion combination to enable safe and cost effective exploration missions. To date, limited experience with such combinations exist, and as a result a comprehensive test program is critical to demonstrating the viability of implementing such a system. The NASA Glenn Research Center has conducted a test program of a 100-lbf (445-N) reaction control engine (RCE) at the center s Altitude Combustion Stand (ACS), focusing on altitude testing over a wide variety of operational conditions. The ACS facility includes a unique propellant conditioning feed system (PCFS) which allows precise control of propellant inlet conditions to the engine. Engine performance as a result of these inlet conditions was examined extensively during the test program. This paper is a companion to the previous specific impulse testing paper, and discusses the pulsed mode operation portion of testing, with a focus on minimum impulse bit (I-bit) and repeatable pulse performance. The engine successfully demonstrated target minimum impulse bit performance at all conditions, as well as successful demonstration of repeatable pulse widths. Some anomalous conditions experienced during testing are also discussed, including a double pulse phenomenon which was not noted in previous test programs for this engine.

  5. Transient interaction between a reaction control jet and a hypersonic crossflow

    Science.gov (United States)

    Miller, Warrick A.; Medwell, Paul R.; Doolan, Con J.; Kim, Minkwan

    2018-04-01

    This paper presents a numerical study that focuses on the transient interaction between a reaction control jet and a hypersonic crossflow with a laminar boundary layer. The aim is to better understand the underlying physical mechanisms affecting the resulting surface pressure and control force. Implicit large-eddy simulations were performed with a round, sonic, perfect air jet issuing normal to a Mach 5 crossflow over a flat plate with a laminar boundary layer, at a jet-to-crossflow momentum ratio of 5.3 and a pressure ratio of 251. The pressure distribution induced on the flat plate is unsteady and is influenced by vortex structures that form around the jet. A horseshoe vortex structure forms upstream and consists of six vortices: two quasi-steady vortices and two co-rotating vortex pairs that periodically coalesce. Shear-layer vortices shed periodically and cause localised high pressure regions that convect downstream with constant velocity. A longitudinal counter-rotating vortex pair is present downstream of the jet and is formed from a series of trailing vortices which rotate about a common axis. Shear-layer vortex shedding causes periodic deformation of barrel and bow shocks. This changes the location of boundary layer separation which also affects the normal force on the plate.

  6. A 3-armed randomized controlled trial of nurses' continuing education meetings on adverse drug reactions.

    Science.gov (United States)

    Sarayani, Amir; Naderi-Behdani, Fahimeh; Hadavand, Naser; Javadi, Mohammadreza; Farsad, Fariborz; Hadjibabaie, Molouk; Gholami, Kheirollah

    2015-01-01

    Nurses' insufficient knowledge of adverse drug reactions is reported as a barrier to spontaneous reporting. Therefore, CE meetings could be utilized to enhance nurses' competencies. In a 3-armed randomized controlled trial, 496 nurses, working in a tertiary medical center, were randomly allocated to a didactic lecture, brainstorming workshop, or the control group (delayed education). Similar instructors (2 clinical pharmacists) prepared and delivered the educational content to all 3 groups. Outcomes were declarative/procedural knowledge (primary outcome), participation rate, and satisfaction. Knowledge was evaluated using a validated researcher-made questionnaire in 3 time points: immediately before, immediately after, and 3 months after each session. Participants' satisfaction was assessed immediately after each meeting via a standard tool. Data were analyzed using appropriate parametric and nonparametric tests. Rate of participation was 37.7% for the lecture group and 47.5% for the workshop group. The workshop participants were significantly more satisfied in comparison with the lecture group (p techniques. © 2015 The Alliance for Continuing Education in the Health Professions, the Society for Academic Continuing Medical Education, and the Council on Continuing Medical Education, Association for Hospital Medical Education.

  7. Controlled Synthesis of Pt Nanowires with Ordered Large Mesopores for Methanol Oxidation Reaction

    Science.gov (United States)

    Zhang, Chengwei; Xu, Lianbin; Yan, Yushan; Chen, Jianfeng

    2016-08-01

    Catalysts for methanol oxidation reaction (MOR) are at the heart of key green-energy fuel cell technology. Nanostructured Pt materials are the most popular and effective catalysts for MOR. Controlling the morphology and structure of Pt nanomaterials can provide opportunities to greatly increase their activity and stability. Ordered nanoporous Pt nanowires with controlled large mesopores (15, 30 and 45 nm) are facilely fabricated by chemical reduction deposition from dual templates using porous anodic aluminum oxide (AAO) membranes with silica nanospheres self-assembled in the channels. The prepared mesoporous Pt nanowires are highly active and stable electrocatalysts for MOR. The mesoporous Pt nanowires with 15 nm mesopores exhibit a large electrochemically active surface area (ECSA, 40.5 m2 g-1), a high mass activity (398 mA mg-1) and specific activity (0.98 mA cm-2), and a good If/Ib ratio (1.15), better than the other mesoporous Pt nanowires and the commercial Pt black catalyst.

  8. Optimizing weight control in diabetes: antidiabetic drug selection

    Directory of Open Access Journals (Sweden)

    S Kalra

    2010-08-01

    Full Text Available S Kalra1, B Kalra1, AG Unnikrishnan2, N Agrawal3, S Kumar41Bharti Hospital, Karnal; 2Amrita Institute of Medical Science, Kochi; 3Medical College, Gwalior; 4Excel Life Sciences, Noida, IndiaDate of preparation: 18th August 2010Conflict of interest: SK has received speaker fees from Novo Nordisk, sanofi-aventis, MSD, Eli Lilly, BMS, and AstraZeneca.Clinical question: Which antidiabetic drugs provide optimal weight control in patients with type 2 diabetes?Results: Metformin reduces weight gain, and may cause weight loss, when given alone or in combination with other drugs. Pioglitazone and rosiglitazone use is associated with weight gain. Use of the glucagon-like peptide-1 (GLP-1 analogs, liraglutide and exenatide, is associated with weight loss. Dipeptidyl peptidase-4 (DPP-4 inhibitors are considered weight-neutral. Results with insulin therapy are conflicting. Insulin detemir provides weight control along with glycemic control.Implementation: • Weight gain is considered an inevitable part of good glycemic control using conventional modalities of treatment such as sulfonylureas.• Use of metformin, weight-sparing insulin analogs such as insulin detemir, and liraglutide, should be encouraged as monotherapy, or in combination with other drugs.Keywords: weight control, diabetes

  9. Some introductory notes on the problem of nuclear energy by controlled fusion reactions

    International Nuclear Information System (INIS)

    Pedretti, E.

    1988-01-01

    Written for scientists and technologist interested in, but unfamiliar with nuclear energy by controlled fusion reactions, this ''sui generis'' review paper attempts to provide the reader, as shortly as possible, with a general idea of the main issues at stake in nuclear fusion research. With the purpose of keeping this paper within a reasonable length, the various subjects are only outlined in their essence, basic features, underlying principles, etc., without entering into details, which are left to the quoted literature. Due to the particular readership of this journal, vacuum problems and/or aspects of fusion research anyhow related with vacuum science and technology are evidentiated. After reviewing fusion reactions' cross sections, fusion by accelerators and muon catalyzed fusion are described, followed by mention of Lawson's criteria and of plasma confinement features. Then, inertial confinement fusion is dealt with, also including one example of laser system (Nova), one of accelerator facility (PBFA-II) and some guesses on the classified Centurion-Halite program. Magnetic confinement fusion research is also reviewed, in particulary reporting one example of linear machine (MFTF-B), two examples of toroidal machines other than Tokamak (ATF and Eta-Beta-II) and various examples of Tokamaks, including PBX and PBX-M; TFTR, JET, JT-60, T-15 and Tore-Supra (large machines); Alcator A, FT, Alcator C/MTX, Alcator C-Mod and T-14 (compact high field machines). Tokamaks under design for ignition experiments (Ignitor, CIT, Ignitex and NET) are also illustrated. Thermal conversion of fusion power and direct generation of electricity are mentioned; conceptual design of fusion power plants are considered and illustrated by four examples (STARFIRE, WILDCAT, MARS and CASCADE). The D 3 He fuel cycle is discussed as an alternative more acceptable than Deuterium-Tritium, and thw Candor proposal is reported. After recalling past experience of the fission power development, some

  10. NUMBER OF SUCCESSIVE CYCLES NECESSARY TO ACHIEVE STABILITY OF SELECTED GROUND REACTION FORCE VARIABLES DURING CONTINUOUS JUMPING

    Directory of Open Access Journals (Sweden)

    Jasmes M.W. Brownjohn

    2009-12-01

    Full Text Available Because of inherent variability in all human cyclical movements, such as walking, running and jumping, data collected across a single cycle might be atypical and potentially unable to represent an individual's generalized performance. The study described here was designed to determine the number of successive cycles due to continuous, repetitive countermovement jumping which a test subject should perform in a single experimental session to achieve stability of the mean of the corresponding continuously measured ground reaction force (GRF variables. Seven vertical GRF variables (period of jumping cycle, duration of contact phase, peak force amplitude and its timing, average rate of force development, average rate of force relaxation and impulse were extracted on the cycle-by-cycle basis from vertical jumping force time histories generated by twelve participants who were jumping in response to regular electronic metronome beats in the range 2-2.8 Hz. Stability of the selected GRF variables across successive jumping cycles was examined for three jumping rates (2, 2.4 and 2.8 Hz using two statistical methods: intra-class correlation (ICC analysis and segmental averaging technique (SAT. Results of the ICC analysis indicated that an average of four successive cycles (mean 4.5 ± 2.7 for 2 Hz; 3.9 ± 2.6 for 2.4 Hz; 3.3 ± 2.7 for 2.8 Hz were necessary to achieve maximum ICC values. Except for jumping period, maximum ICC values took values from 0.592 to 0.991 and all were significantly (p < 0.05 different from zero. Results of the SAT revealed that an average of ten successive cycles (mean 10.5 ± 3.5 for 2 Hz; 9.2 ± 3.8 for 2.4 Hz; 9.0 ± 3.9 for 2.8 Hz were necessary to achieve stability of the selected parameters using criteria previously reported in the literature. Using 10 reference trials, the SAT required standard deviation criterion values of 0.49, 0.41 and 0.55 for 2 Hz, 2.4 Hz and 2.8 Hz jumping rates, respectively, in order to approximate

  11. Generation of American elm trees with tolerance to Dutch elm disease through controlled crosses and selection

    Science.gov (United States)

    James M. Slavicek; Kathleen S. Knight

    2012-01-01

    The goal of our research and development efforts is to generate new and/or improved selections of the American elm (Ulmus americana L.) with tolerance/resistance to Dutch elm disease (DED). The approaches we are taking for this effort include: 1) controlled breeding using known DED -tolerant selections, 2) controlled breeding using DED-tolerant...

  12. Optimal Selective Harmonic Control for Power Harmonics Mitigation

    DEFF Research Database (Denmark)

    Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede

    2015-01-01

    of power harmonics. The proposed optimal SHC is of hybrid structure: all recursive SHC modules with weighted gains are connected in parallel. It bridges the real “nk+-m order RC” and the complex “parallel structure RC”. Compared to other IMP based control solutions, it offers an optimal trade-off among...

  13. Targeting ticks for control of selected hemoparasitic diseases of cattle.

    Science.gov (United States)

    Kocan, K M

    1995-03-01

    Development in and transmission of hemoparasites by tick vectors are phenomena closely synchronized with the tick feeding cycle. In all known life cycles, initial infection of tick tissues occurs in midgut epithelial cells and transmission is effected as ticks feed after parasites have developed and multiplied in salivary glands. Many factors reviewed affect development and transmission of hemoparasites by ticks including age of ticks, artificial temperature, climate and/or season, tick stage or sex, hemoparasite variation, concurrent infection of ticks with other pathogens, host cell susceptibility, transovarial transmission, effect of hemoparasites on tick biology, and the effect of infecting parasitemia level in cattle on infection rates in ticks. Four hemoparasites of cattle, Anaplasma marginale, Cowdria ruminantium, Theileria parva, and Babesia spp., are all dependent on ticks for biological transmission. Babesia is transmitted transovarially whereas the other three are transmitted transstadially. Mechanical transfer of infective blood via fomites and mouthparts of biting arthropods is also a major means of transmission for Anaplasma marginale but not of the others. Potential control methods for hemoparasites that target parasites as they are developing in their respective tick hosts include tick control, vaccines (against ticks and parasites), and drugs (against ticks and parasites). Successful application of control strategies will be dependent upon thorough understanding of parasite developmental cycles, biology of the tick vectors and the immune response of cattle to ticks and to hemoparasites. The most effective control measures will be those that are targeted against both ticks and the hemoparasites they vector.

  14. Modeling the Influence of Diffusion-Controlled Reactions and Residual Termination and Deactivation on the Rate and Control of Bulk ATRP at High Conversions

    Directory of Open Access Journals (Sweden)

    Ali Mohammad Rabea

    2015-04-01

    Full Text Available In high-conversion atom transfer radical polymerization (ATRP, all the reactions, such as radical termination, radical deactivation, dormant chain activation, monomer propagation, etc. could become diffusion controlled sooner or later, depending on relative diffusivities of the involved reacting species. These diffusion-controlled reactions directly affect the rate of polymerization and the control of polymer molecular weight. A model is developed to investigate the influence of diffusion-controlled reactions on the high conversion ATRP kinetics. Model simulation reveals that diffusion-controlled termination slightly increases the rate, but it is the diffusion-controlled deactivation that causes auto-acceleration in the rate (“gel effect” and loss of control. At high conversions, radical chains are “trapped” because of high molecular weight. However, radical centers can still migrate through (1 radical deactivation–activation cycles and (2 monomer propagation, which introduce “residual termination” reactions. It is found that the “residual termination” does not have much influence on the polymerization kinetics. The migration of radical centers through propagation can however facilitate catalytic deactivation of radicals, which improves the control of polymer molecular weight to some extent. Dormant chain activation and monomer propagation also become diffusion controlled and finally stop the polymerization when the system approaches its glass state.

  15. Real-time nonlinear feedback control of pattern formation in (bio)chemical reaction-diffusion processes: a model study.

    Science.gov (United States)

    Brandt-Pollmann, U; Lebiedz, D; Diehl, M; Sager, S; Schlöder, J

    2005-09-01

    Theoretical and experimental studies related to manipulation of pattern formation in self-organizing reaction-diffusion processes by appropriate control stimuli become increasingly important both in chemical engineering and cellular biochemistry. In a model study, we demonstrate here exemplarily the application of an efficient nonlinear model predictive control (NMPC) algorithm to real-time optimal feedback control of pattern formation in a bacterial chemotaxis system modeled by nonlinear partial differential equations. The corresponding drift-diffusion model type is representative for many (bio)chemical systems involving nonlinear reaction dynamics and nonlinear diffusion. We show how the computed optimal feedback control strategy exploits the system inherent physical property of wave propagation to achieve desired control aims. We discuss various applications of our approach to optimal control of spatiotemporal dynamics.

  16. Controllability of multi-partite quantum systems and selective excitation of quantum dots

    International Nuclear Information System (INIS)

    Schirmer, S G; Pullen, I C H; Solomon, A I

    2005-01-01

    We consider the degrees of controllability of multi-partite quantum systems, as well as necessary and sufficient criteria for each case. The results are applied to the problem of simultaneous control of an ensemble of quantum dots with a single laser pulse. Finally, we apply optimal control techniques to demonstrate selective excitation of individual dots for a simultaneously controllable ensemble of quantum dots

  17. Highly selective transformation of ammonia nitrogen to N2 based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions system.

    Science.gov (United States)

    Ji, Youzhi; Bai, Jing; Li, Jinhua; Luo, Tao; Qiao, Li; Zeng, Qingyi; Zhou, Baoxue

    2017-11-15

    A highly selective method for transforming ammonia nitrogen to N 2 was proposed, based on a novel solar-driven photoelectrocatalytic-chlorine radical reactions (PEC-chlorine) system. The PEC-chlorine system was facilitated by a visible light response WO 3 nanoplate array (NPA) electrode in an ammonia solution containing chloride ions (Cl - ). Under illumination, photoholes from WO 3 promote the oxidation of Cl - to chlorine radical (Cl). This radical can selectively transform ammonia nitrogen to N 2 (79.9%) and NO 3 - (19.2%), similar to the breakpoint chlorination reaction. The ammonia nitrogen removal efficiency increased from 10.6% (PEC without Cl - ) to 99.9% with the PEC-chlorine system within 90 min operation, which can be attributed to the cyclic reactions between Cl - /Cl and the reaction intermediates (NH 2 , NHCl, etc.) that expand the degradation reactions from the surface of the electrodes to the whole solution system. Moreover, Cl is the main radical species contributing to the transformation of ammonia nitrogen to N 2 , which is confirmed by the tBuOH capture experiment. Compared to conventional breakpoint chlorination, the PEC-chlorine system is a more economical and efficient means for ammonia nitrogen degradation because of the fast removal rate, no additional chlorine cost, and its use of clean energy (since it is solar-driven). Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Selection of controls in case-control studies on maternal medication use and risk of birth defects

    NARCIS (Netherlands)

    Bakker, M.K.; de Walle, H.E.; Dequito, A.; van den Berg, P.B.; de Jong-van den Berg, L.T.

    BACKGROUND:: In case-control studies on teratogenic risks of maternal drug use during pregnancy, the use of normal or malformed controls may lead to recall-bias or selection bias. This can be avoided by using controls with a genetic disorder. However, researchers are hesitant to use these as

  19. Identification and characterization of novel long-term metabolites of oxymesterone and mesterolone in human urine by application of selected reaction monitoring GC-CI-MS/MS.

    Science.gov (United States)

    Polet, Michael; Van Gansbeke, Wim; Geldof, Lore; Deventer, Koen; Van Eenoo, Peter

    2017-11-01

    The search for metabolites with longer detection times remains an important task in, for example, toxicology and doping control. The impact of these long-term metabolites is highlighted by the high number of positive cases after reanalysis of samples that were stored for several years, e.g. samples of previous Olympic Games. A substantial number of previously alleged negative samples have now been declared positive due to the detection of various long-term steroid metabolites the existence of which was unknown during the Olympic Games of 2008 and 2012. In this work, the metabolism of oxymesterone and mesterolone, two anabolic androgenic steroids (AAS), was investigated by application of a selected reaction monitoring gas chromatography-chemical ionization-triple quadrupole mass spectrometry (GC-CI-MS/MS) protocol for metabolite detection and identification. Correlations between AAS structure and GC-CI-MS/MS fragmentation behaviour enabled the search for previously unknown but expected AAS metabolites by selection of theoretical transitions for expected metabolites. Use of different hydrolysis protocols allowed for evaluation of the detection window of both phase I and phase II metabolites. For oxymesterone, a new metabolite, 18-nor-17β-hydroxymethyl-17α-methyl-4-hydroxy-androst-4,13-diene-3-one, was identified. It was detectable up to 46 days by using GC-CI-MS/MS, whereas with a traditional screening (detection of metabolite 17-epioxymesterone with electron ionization GC-MS/MS) oxymesterone administration was only detectable for 3.5 days. A new metabolite was also found for mesterolone. It was identified as 1α-methyl-5α-androstan-3,6,16-triol-17-one and its sulfate form after hydrolysis with Helix pomatia resulted in a prolonged detection time (up to 15 days) for mesterolone abuse. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  20. Reaction of the (111) faces of single-crystal indium phosphide with alkylating agents: evidence for selective reaction of the p-rich face

    Energy Technology Data Exchange (ETDEWEB)

    Spool, A.M.; Daube, K.A.; Mallouk, T.E.; Belmont, J.A.; Wrighton, M.S.

    1986-05-28

    We wish to report that the P-rich, (111)B, face of single-crystal InP, but not the In-rich, (111)A, face of the same crystal, reacts with molecular reagents to yield surface-bound material derived from the apparent alkylation of a surface P atom. Exploitation of surface functional groups has been demonstrated to be very important in the attachment of molecular reagents and polymers to electrode surfaces. Electrodes derivatized with molecules have potential uses in analysis, fuel cells, electrosynthetic cells, and photoelectrochemical cells. We now wish to present evidence showing that an important photoelectrode material, InP, can be functionalized with molecules by reaction of the P-rich, (111)B, face with alkylating reagents.

  1. Catalytic Organometallic Reactions of Ammonia

    Science.gov (United States)

    Klinkenberg, Jessica L.

    2012-01-01

    Until recently, ammonia had rarely succumbed to catalytic transformations with homogeneous catalysts, and the development of such reactions that are selective for the formation of single products under mild conditions has encountered numerous challenges. However, recently developed catalysts have allowed several classes of reactions to create products with nitrogen-containing functional groups from ammonia. These reactions include hydroaminomethylation, reductive amination, alkylation, allylic substitution, hydroamination, and cross-coupling. This Minireview describes examples of these processes and the factors that control catalyst activity and selectivity. PMID:20857466

  2. Two-pulse atomic coherent control spectroscopy of Eley-Rideal reactions: An application of an atom laser

    International Nuclear Information System (INIS)

    Joergensen, Solvejg; Kosloff, Ronnie

    2003-01-01

    A spectroscopic application of the atom laser is suggested. The spectroscopy termed 2PACC (two-pulse atomic coherent control) employs the coherent properties of matter waves from a two-pulse atom laser. These waves are employed to control a gas-surface chemical recombination reaction. The method is demonstrated for an Eley-Rideal reaction of a hydrogen or alkali atom-laser pulse where the surface target is an adsorbed hydrogen atom. The reaction yields either a hydrogen or alkali hydride molecule. The desorbed gas-phase molecular yield and its internal state is shown to be controlled by the time and phase delay between two atom-laser pulses. The calculation is based on solving the time-dependent Schroedinger equation in a diabatic framework. The probability of desorption which is the predicted 2PACC signal has been calculated as a function of the pulse parameters

  3. A computational study on Lewis acid-catalyzed diastereoselective acyclic radical allylation reactions with unusual selectivity dependence on temperature and epimer precursor.

    Science.gov (United States)

    Georgieva, Miglena K; Santos, A Gil

    2014-12-05

    In stereoselective radical reactions, it is accepted that the configuration of the radical precursor has no impact on the levels of stereoinduction, as a prochiral radical intermediate is planar, with two identical faces, independently of its origin. However, Sibi and Rheault (J. Am. Chem. Soc. 2000, 122, 8873-8879) remarkably obtained different selectivities in the trapping of radicals originated from two epimeric bromides, catalyzed by chelating Lewis acids. The selectivity rationalization was made on the basis of different conformational properties of each epimer. However, in this paper we show that the two epimers have similar conformational properties, which implies that the literature proposal is unable to explain the experimental results. We propose an alternative mechanism, in which the final selectivity is dependent on different reaction rates for radical formation from each epimer. By introducing a different perspective of the reaction mechanism, our model also allows the rationalization of different chemical yields obtained from each epimer, a result not rationalized by the previous model. Adaptation to other radical systems, under different reaction conditions, is also possible.

  4. Material selection and corrosion control practices in petroleum production

    International Nuclear Information System (INIS)

    Tuttle, R.N.

    1980-01-01

    The intent of this paper is to review briefly the current state of the art and to discuss some of the anticipated future oil and gas drilling and production activities which may challenge the materials selection and corrosion technologies. The current state of art discussions in this paper have been augmented by providing a list of references so that interested engineers may delve into each subject in more detail as desired. The technological areas which appear to require additional input to meet future needs include high strength tubular goods for sour gas service, corrosion resistant high strength alloys, definition of the effects of pressure, temperature, and fluid composition on corrosion behavior, and fatigue properties of various steels in seawater

  5. Control room annunciation - problem assessment and selection of improvement priorities

    International Nuclear Information System (INIS)

    Hartley, P.; Yaraskavitch, E.; Davey, E.

    1998-01-01

    In 1997, Pickering B undertook a project to examine current annunciation practice and identify improvement opportunities and priorities. The objectives and scope of the study were to: document the deficiencies with control room annunciation and the subsequent operational and financial impacts to station operations, develop an operations-based definition of the requirements for annunciation to adequately support control room staff, propose annunciation improvements based on a comparison of the annunciation deficiencies identified and the operational needs to be met, assess the relative operational impact, and financial benefits and costs of the improvement initiatives proposed, and recommend annunciation improvement priorities that offer a mix of operational and financial return for improvement investment. This paper discusses the rationale for the project, outlines the approaches applied in achieving the assessment objectives, reviews the key assessment findings and describes the improvement initiatives recommended. (author)

  6. Optimum Actuator Selection with a Genetic Algorithm for Aircraft Control

    Science.gov (United States)

    Rogers, James L.

    2004-01-01

    The placement of actuators on a wing determines the control effectiveness of the airplane. One approach to placement maximizes the moments about the pitch, roll, and yaw axes, while minimizing the coupling. For example, the desired actuators produce a pure roll moment without at the same time causing much pitch or yaw. For a typical wing, there is a large set of candidate locations for placing actuators, resulting in a substantially larger number of combinations to examine in order to find an optimum placement satisfying the mission requirements and mission constraints. A genetic algorithm has been developed for finding the best placement for four actuators to produce an uncoupled pitch moment. The genetic algorithm has been extended to find the minimum number of actuators required to provide uncoupled pitch, roll, and yaw control. A simplified, untapered, unswept wing is the model for each application.

  7. Optimal control of a Cope rearrangement by coupling the reaction path to a dissipative bath or a second active mode

    International Nuclear Information System (INIS)

    Chenel, A.; Meier, C.; Dive, G.; Desouter-Lecomte, M.

    2015-01-01

    We compare the strategy found by the optimal control theory in a complex molecular system according to the active subspace coupled to the field. The model is the isomerization during a Cope rearrangement of Thiele’s ester that is the most stable dimer obtained by the dimerization of methyl-cyclopentadienenylcarboxylate. The crudest partitioning consists in retaining in the active space only the reaction coordinate, coupled to a dissipative bath of harmonic oscillators which are not coupled to the field. The control then fights against dissipation by accelerating the passage across the transition region which is very wide and flat in a Cope reaction. This mechanism has been observed in our previous simulations [Chenel et al., J. Phys. Chem. A 116, 11273 (2012)]. We compare here, the response of the control field when the reaction path is coupled to a second active mode. Constraints on the integrated intensity and on the maximum amplitude of the fields are imposed limiting the control landscape. Then, optimum field from one-dimensional simulation cannot provide a very high yield. Better guess fields based on the two-dimensional model allow the control to exploit different mechanisms providing a high control yield. By coupling the reaction surface to a bath, we confirm the link between the robustness of the field against dissipation and the time spent in the delocalized states above the transition barrier

  8. An Interaction Measure for Control Configuration Selection for Multivariable Bilinear Systems

    DEFF Research Database (Denmark)

    Shaker, Hamid Reza; Stoustrup, Jakob

    2013-01-01

    are needed to be controlled, are nonlinear and linear models are insufficient to describe the behavior of the processes. The focus of this paper is on the problem of control configuration selection for a class of nonlinear systems which is known as bilinear systems. A gramian-based interaction measure...... for control configuration selection of MIMO bilinear processes is described. In general, most of the results on the control configuration selection, which have been proposed so far, can only support linear systems. The proposed gramian-based interaction measure not only supports bilinear processes but also...

  9. Selective coupling reaction between 2,6-diiodoanisoles and terminal alkynes catalyzed by Pd(PPh32Cl2 and CuI

    Directory of Open Access Journals (Sweden)

    Allan F. C. Rossini

    2012-06-01

    Full Text Available The cross-coupling reaction between aryl halides and terminal alkynes, catalyzed by palladium complexes and copper (I salts, consists in an efficient synthetic tool for the formation of C-C bonds, resulting in disubstituted acetylenic compounds. Accordingly, in this work we present our preliminary results involving the selective cross-coupling reaction between 2,6-diiodoanisoles and terminal alkynes, catalyzed by Pd(PPh32Cl2 and CuI, in the formation of 2-iodo-alkynylanisoles (scheme 1.

  10. Cost-Effective Control of Infectious Disease Outbreaks Accounting for Societal Reaction.

    Science.gov (United States)

    Fast, Shannon M; González, Marta C; Markuzon, Natasha

    2015-01-01

    Studies of cost-effective disease prevention have typically focused on the tradeoff between the cost of disease transmission and the cost of applying control measures. We present a novel approach that also accounts for the cost of social disruptions resulting from the spread of disease. These disruptions, which we call social response, can include heightened anxiety, strain on healthcare infrastructure, economic losses, or violence. The spread of disease and social response are simulated under several different intervention strategies. The modeled social response depends upon the perceived risk of the disease, the extent of disease spread, and the media involvement. Using Monte Carlo simulation, we estimate the total number of infections and total social response for each strategy. We then identify the strategy that minimizes the expected total cost of the disease, which includes the cost of the disease itself, the cost of control measures, and the cost of social response. The model-based simulations suggest that the least-cost disease control strategy depends upon the perceived risk of the disease, as well as media intervention. The most cost-effective solution for diseases with low perceived risk was to implement moderate control measures. For diseases with higher perceived severity, such as SARS or Ebola, the most cost-effective strategy shifted toward intervening earlier in the outbreak, with greater resources. When intervention elicited increased media involvement, it remained important to control high severity diseases quickly. For moderate severity diseases, however, it became most cost-effective to implement no intervention and allow the disease to run its course. Our simulation results imply that, when diseases are perceived as severe, the costs of social response have a significant influence on selecting the most cost-effective strategy.

  11. Cost-Effective Control of Infectious Disease Outbreaks Accounting for Societal Reaction.

    Directory of Open Access Journals (Sweden)

    Shannon M Fast

    Full Text Available Studies of cost-effective disease prevention have typically focused on the tradeoff between the cost of disease transmission and the cost of applying control measures. We present a novel approach that also accounts for the cost of social disruptions resulting from the spread of disease. These disruptions, which we call social response, can include heightened anxiety, strain on healthcare infrastructure, economic losses, or violence.The spread of disease and social response are simulated under several different intervention strategies. The modeled social response depends upon the perceived risk of the disease, the extent of disease spread, and the media involvement. Using Monte Carlo simulation, we estimate the total number of infections and total social response for each strategy. We then identify the strategy that minimizes the expected total cost of the disease, which includes the cost of the disease itself, the cost of control measures, and the cost of social response.The model-based simulations suggest that the least-cost disease control strategy depends upon the perceived risk of the disease, as well as media intervention. The most cost-effective solution for diseases with low perceived risk was to implement moderate control measures. For diseases with higher perceived severity, such as SARS or Ebola, the most cost-effective strategy shifted toward intervening earlier in the outbreak, with greater resources. When intervention elicited increased media involvement, it remained important to control high severity diseases quickly. For moderate severity diseases, however, it became most cost-effective to implement no intervention and allow the disease to run its course. Our simulation results imply that, when diseases are perceived as severe, the costs of social response have a significant influence on selecting the most cost-effective strategy.

  12. Photocatalysis reaction on ordered arrays of Au nanorads with controlled orientations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Jung; Han, Sang Woo [Dept. of Chemistry and KI for the NanoCentury, KAIST, Daejeon (Korea, Republic of)

    2015-03-15

    Surface photocatalysis reactions of aromatic compounds self-assembled on metal surfaces have been extensively explored for the past decades. Despite the numerous studies on the surface photocatalysis reactions of aromatic compounds, that on Au surface has rarely been reported due to the inefficiency of Au toward these reactions compared to Ag. The detailed experimental and theoretical studies on the mechanism of the enhanced photocatalytic function of the AuNR arrays are currently underway.

  13. Goal selection versus process control in a brain-computer interface based on sensorimotor rhythms.

    Science.gov (United States)

    Royer, Audrey S; He, Bin

    2009-02-01

    In a brain-computer interface (BCI) utilizing a process control strategy, the signal from the cortex is used to control the fine motor details normally handled by other parts of the brain. In a BCI utilizing a goal selection strategy, the signal from the cortex is used to determine the overall end goal of the user, and the BCI controls the fine motor details. A BCI based on goal selection may be an easier and more natural system than one based on process control. Although goal selection in theory may surpass process control, the two have never been directly compared, as we are reporting here. Eight young healthy human subjects participated in the present study, three trained and five naïve in BCI usage. Scalp-recorded electroencephalograms (EEG) were used to control a computer cursor during five different paradigms. The paradigms were similar in their underlying signal processing and used the same control signal. However, three were based on goal selection, and two on process control. For both the trained and naïve populations, goal selection had more hits per run, was faster, more accurate (for seven out of eight subjects) and had a higher information transfer rate than process control. Goal selection outperformed process control in every measure studied in the present investigation.

  14. Goal selection versus process control while learning to use a brain-computer interface

    Science.gov (United States)

    Royer, Audrey S.; Rose, Minn L.; He, Bin

    2011-06-01

    A brain-computer interface (BCI) can be used to accomplish a task without requiring motor output. Two major control strategies used by BCIs during task completion are process control and goal selection. In process control, the user exerts continuous control and independently executes the given task. In goal selection, the user communicates their goal to the BCI and then receives assistance executing the task. A previous study has shown that goal selection is more accurate and faster in use. An unanswered question is, which control strategy is easier to learn? This study directly compares goal selection and process control while learning to use a sensorimotor rhythm-based BCI. Twenty young healthy human subjects were randomly assigned either to a goal selection or a process control-based paradigm for eight sessions. At the end of the study, the best user from each paradigm completed two additional sessions using all paradigms randomly mixed. The results of this study were that goal selection required a shorter training period for increased speed, accuracy, and information transfer over process control. These results held for the best subjects as well as in the general subject population. The demonstrated characteristics of goal selection make it a promising option to increase the utility of BCIs intended for both disabled and able-bodied users.

  15. An Elegant Example of Chemoselective Reaction

    Indian Academy of Sciences (India)

    Srimath

    mental pollution. Selectivity ... teaching our undergraduate chemistry students, though many reactions that ... mide drugs, which made a great impact on health care by control- ... What is the reason for the distinctly different behaviour of the.

  16. Kinetics and Mechanism of the Gas-Phase Reaction of Selected Carbonyls with Cl Atoms between 250 and 340 K

    Science.gov (United States)

    Hasson, A. S.; Algrim, L.; Abdelhamid, A.; Tyndall, G. S.; Orlando, J. J.

    2013-12-01

    Carbonyls are important products from the gas phase degradation of most volatile organic compounds. Their atmospheric reactions therefore have a significant impact on atmospheric composition, particularly in aged air masses. While the reactions of short-chain linear carbonyls are well understood, the chemistry of larger (> C6) and branched carbonyl is more uncertain. To provide insight into these reactions, the reactions of three carbonyls (methyl isopropyl ketone, MIK; di-isopropyl ketone, DIK; and diethyl ketone, DEK) with chlorine atoms were investigated between 250 and 340 K and 1 atm in the presence and absence of NOx and an HO2 source (methanol). Experiments were performed in a photochemical reactor using a combination of long-path Fourier transform infra-red spectroscopy, proton transfer reaction mass spectrometry and gas chromatography with flame ionization detection. The kinetics were studied using the relative rate technique with butanone and isopropanol as the reference compounds. The Arrhenius expression for the three rate coefficients was determined to be k(DEK+Cl) = 3.87 x 10-11e(2 × 7 kJ/mol)/RT cm3 molecules-1 s-1 , k(MIPK+Cl) = 7.20 x 10-11e(0.2× 8 kJ/mol)/RT cm3 molecules-1 s-1 , and k(DIPK+Cl) = 3.33 x 10-10e(-3× 8 kJ/mol)/RT cm3 molecules-1 s-1 . Measured reaction products accounted for 38-72 % of the reacted carbon and were consistent with strong deactivation of the carbon atom adjacent to the carbonyl group with respect to H-atom abstraction by Cl atoms. The product distributions also provide insight into radical recycling from the organic peroxy + HO2 reaction, and the relative rates of isomerization, fragmentation and reaction with O2 for carbonyl-containing alkoxy radicals. Implications of these results will be discussed.

  17. A Model for Service Life Control of Selected Device Systems

    Directory of Open Access Journals (Sweden)

    Zieja Mariusz

    2014-04-01

    Full Text Available This paper presents a way of determining distribution of limit state exceedence time by a diagnostic parameter which determines accuracy of maintaining zero state. For calculations it was assumed that the diagnostic parameter is deviation from nominal value (zero state. Change of deviation value occurs as a result of destructive processes which occur during service. For estimation of deviation increasing rate in probabilistic sense, was used a difference equation from which, after transformation, Fokker-Planck differential equation was obtained [4, 11]. A particular solution of the equation is deviation increasing rate density function which was used for determining exceedance probability of limit state. The so-determined probability was then used to determine density function of limit state exceedance time, by increasing deviation. Having at disposal the density function of limit state exceedance time one determined service life of a system of maladjustment. In the end, a numerical example based on operational data of selected aircraft [weapon] sights was presented. The elaborated method can be also applied to determining residual life of shipboard devices whose technical state is determined on the basis of analysis of values of diagnostic parameters.

  18. Addressing selected problems of the modelling of digital control systems

    International Nuclear Information System (INIS)

    Sedlak, J.

    2004-12-01

    The introduction of digital systems to practical activities at nuclear power plants brings about new requirements for their modelling for the purposes of reliability analyses required for plant licensing as well as for inclusion into PSA studies and subsequent use in applications for the assessment of events, limits and conditions, and risk monitoring. It is very important to assess, both qualitatively and quantitatively, the effect of this change on operational safety. The report describes selected specific features of reliability analysis of digital system and recommends methodological procedures. The chapters of the report are as follows: (1) Flexibility and multifunctionality of the system. (2) General framework of reliability analyses (Understanding the system; Qualitative analysis; Quantitative analysis; Assessment of results, comparison against criteria; Documenting system reliability analyses; Asking for comments and their evaluation); and (3) Suitable reliability models (Reliability models of basic events; Monitored components with repair immediately following defect or failure; Periodically tested components; Constant unavailability (probability of failure to demand); Application of reliability models for electronic components; Example of failure rate decomposition; Example modified for diagnosis successfulness; Transfer of reliability analyses to PSA; Common cause failures - CCF; Software backup and CCF type failures, software versus hardware). (P.A.)

  19. Multiple reaction monitoring targeted LC-MS analysis of potential cell death marker proteins for increased bioprocess control.

    Science.gov (United States)

    Albrecht, Simone; Kaisermayer, Christian; Reinhart, David; Ambrose, Monica; Kunert, Renate; Lindeberg, Anna; Bones, Jonathan

    2018-05-01

    The monitoring of protein biomarkers for the early prediction of cell stress and death is a valuable tool for process characterization and efficient biomanufacturing control. A representative set of six proteins, namely GPDH, PRDX1, LGALS1, CFL1, TAGLN2 and MDH, which were identified in a previous CHO-K1 cell death model using discovery LC-MS E was translated into a targeted liquid chromatography multiple reaction monitoring mass spectrometry (LC-MRM-MS) platform and verified. The universality of the markers was confirmed in a cell growth model for which three Chinese hamster ovary host cell lines (CHO-K1, CHO-S, CHO-DG44) were grown in batch culture in two different types of basal media. LC-MRM-MS was also applied to spent media (n = 39) from four perfusion biomanufacturing series. Stable isotope-labelled peptide analogues and a stable isotope-labelled monoclonal antibody were used for improved protein quantitation and simultaneous monitoring of the workflow reproducibility. Significant increases in protein concentrations were observed for all viability marker proteins upon increased dead cell numbers and allowed for discrimination of spent media with dead cell densities below and above 1 × 10 6  dead cells/mL which highlights the potential of the selected viability marker proteins in bioprocess control. Graphical abstract Overview of the LC-MRM-MS workflow for the determination of proteomic markers in conditioned media from the bioreactor that correlate with CHO cell death.

  20. Measurement from sun-synchronous orbit of a reaction rate controlling the diurnal NOx cycle in the stratosphere

    Directory of Open Access Journals (Sweden)

    A. Dudhia

    2011-05-01

    Full Text Available A reaction rate associated with the nighttime formation of an important diurnally varying species, N2O5, is determined from MIPAS-ENVISAT. During the day, photolysis of N2O5 in the stratosphere contributes to nitrogen-catalysed ozone destruction. However, at night concentrations of N2O5 increase, temporarily sequestering reactive NOx NO and NO2 in a natural cycle which regulates the majority of stratospheric ozone. In this paper, the reaction rate controlling the formation of N2O5 is determined from this instrument for the first time. The observed reaction rate is compared to the currently accepted rate determined from laboratory measurements. Good agreement is obtained between the observed and accepted experimental reaction rates within the error bars.

  1. Review of selected dynamic material control functions for international safeguards

    International Nuclear Information System (INIS)

    Lowry, L.L.

    1980-09-01

    With the development of Dynamic Special Nuclear Material Accounting and Control systems used in nuclear manufacturing and reprocessing plants, there arises the question as to how these systems affect the IAEA inspection capabilities. The systems in being and under development provide information and control for a variety of purposes important to the plant operator, the safeguards purpose being one of them. This report attempts to judge the usefulness of these dynamic systems to the IAEA and have defined 12 functions that provide essential information to it. If the information acquired by these dynamic systems is to be useful to the IAEA, the inspectors must be able to independently verify it. Some suggestions are made as to how this might be done. But, even if it should not be possible to verify all the data, the availability to the IAEA of detailed, simultaneous, and plant-wide information would tend to inhibit a plant operator from attempting to generate a floating or fictitious inventory. Suggestions are made that might be helpful in the design of future software systems, an area which has proved to be fatally deficient in some systems and difficult in all

  2. Ancillary effects of selected acid deposition control policies

    Energy Technology Data Exchange (ETDEWEB)

    Moe, R.J.; Lyke, A.J.; Nesse, R.J.

    1986-08-01

    NAPAP is examining a number of potential ways to reduce the precursors (sulfur dioxide and nitrogen oxides) to acid deposition. However, the policies to reduce acid deposition will have other physical, biological and economic effects unrelated to acid deposition. For example, control policies that reduce sulfur dioxide emissions may also increase visibility. The effects of an acid deposition policy that are unrelated to acid deposition are referred to as ''ancillary'' effects. This reserch identifies and characterizes the principle physical and economic ancillary effects associated with acid deposition control and mitigation policies. In this study the ancillary benefits associated with four specific acid deposition policy options were investigated. The four policy options investigated are: (1) flue gas desulfurization, (2) coal blending or switching, (3) reductions in automobile emissions of NO/sub x/, and (4) lake liming. Potential ancillary benefits of each option were identified and characterized. Particular attention was paid to the literature on economic valuation of potential ancillary effects.

  3. Morphological control of strontium oxalate particles by PSMA-mediated precipitation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yu Jiaguo [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)]. E-mail: jiaguoyu@yahoo.com; Tang Hua [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Cheng Bei [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2005-05-15

    In this paper, strontium oxalate particles with different morphologies could be easily obtained by a precipitation reaction of sodium oxalate with strontium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA). The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The effects of pH, aging time and concentration of PSMA on the phase structures and morphologies of the as-prepared strontium oxalate particles were investigated and discussed. The results showed that strontium oxalate particles with various morphologies, such as, bi-pyramids, rods, peanuts, and spherical particles, etc., could be obtained by varying the experimental conditions. PSMA promoted the formation of strontium oxalate dihydrate (SOD) phase. Suitable pH values (pH 7 and 8) favor the formation of the peanut-shaped SrC{sub 2}O{sub 4} particles. This research may provide new insight into the control of morphologies and phase structures of strontium oxalate particles and the biomimetic synthesis of novel inorganic materials.

  4. Glutaredoxin-2 is required to control oxidative phosphorylation in cardiac muscle by mediating deglutathionylation reactions.

    Science.gov (United States)

    Mailloux, Ryan J; Xuan, Jian Ying; McBride, Skye; Maharsy, Wael; Thorn, Stephanie; Holterman, Chet E; Kennedy, Christopher R J; Rippstein, Peter; deKemp, Robert; da Silva, Jean; Nemer, Mona; Lou, Marjorie; Harper, Mary-Ellen

    2014-05-23

    Glutaredoxin-2 (Grx2) modulates the activity of several mitochondrial proteins in cardiac tissue by catalyzing deglutathionylation reactions. However, it remains uncertain whether Grx2 is required to control mitochondrial ATP output in heart. Here, we report that Grx2 plays a vital role modulating mitochondrial energetics and heart physiology by mediating the deglutathionylation of mitochondrial proteins. Deletion of Grx2 (Grx2(-/-)) decreased ATP production by complex I-linked substrates to half that in wild type (WT) mitochondria. Decreased respiration was associated with increased complex I glutathionylation diminishing its activity. Tissue glucose uptake was concomitantly increased. Mitochondrial ATP output and complex I activity could be recovered by restoring the redox environment to that favoring the deglutathionylated states of proteins. Grx2(-/-) hearts also developed left ventricular hypertrophy and fibrosis, and mice became hypertensive. Mitochondrial energetics from Grx2 heterozygotes (Grx2(+/-)) were also dysfunctional, and hearts were hypertrophic. Intriguingly, Grx2(+/-) mice were far less hypertensive than Grx2(-/-) mice. Thus, Grx2 plays a vital role in modulating mitochondrial metabolism in cardiac muscle, and Grx2 deficiency leads to pathology. As mitochondrial ATP production was restored by the addition of reductants, these findings may be relevant to novel redox-related therapies in cardiac disease. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Non-Toxic Dual Thrust Reaction Control Engine Development for On-Orbit APS Applications

    Science.gov (United States)

    Robinson, Philip J.; Veith, Eric M.

    2003-01-01

    A non-toxic dual thrust proof-of-concept demonstration engine was successfully tested at the Aerojet Sacramento facility under a technology contract sponsored by the National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center (MSFC). The goals of the NASA MSFC contract (NAS8-01109) were to develop and expand the technical maturity of a non-toxic, on-orbit auxiliary propulsion system (APS) thruster under the Next Generation Launch Technology (NGLT) program. The demonstration engine utilized the existing Kistler K-1 870 lbf LOX/Ethanol orbital maneuvering engine ( O m ) coupled with some special test equipment (STE) that enabled engine operation at 870 lbf in the primary mode and 25 lbf in the vernier mode. Ambient testing in primary mode varied mixture ratio (MR) from 1.28 to 1.71 and chamber pressure (P(c) from 110 to 181 psia, and evaluated electrical pulse widths (EPW) of 0.080, 0.100 and 0.250 seconds. Altitude testing in vernier mode explored igniter and thruster pulsing characteristics, long duration steady state operation (greater than 420 sec) and the impact of varying the percent fuel film cooling on vernier performance and chamber thermal response at low PC (4 psia). Data produced from the testing provided calibration of the performance and thermal models used in the design of the next version of the dual thrust Reaction Control Engine (RCE).

  6. Controlling Solid–Liquid Conversion Reactions for a Highly Reversible Aqueous Zinc–Iodine Battery

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Huilin; Li, Bin; Mei, Donghai; Nie, Zimin; Shao, Yuyan; Li, Guosheng; Li, Xiaohong S.; Han, Kee Sung; Muller, Karl T.; Sprenkle, Vincent L.; Liu, Jun

    2017-10-30

    Aqueous rechargeable batteries are desirable for many energy storage applications due to their low cost and high safety. However, low capacity and short cycle life are the significant obstacles to their practical applications. Here, we demonstrate a highly reversible aqueous zinc-iodine battery using encapsulated iodine in microporous active carbon fibers (ACFs) as cathode materials through the rational control of solid-liquid conversion reactions. The experiments and density function theory (DFT) calculations were employed to investigate the effects of solvents and properties of carbon hosts, e.g. pore size, surface chemistries, on the adsorption of iodine species. The rational manipulation of the competition between the adsorption in carbon and solvation in electrolytes for iodine species is responsible for the high reversibility and cycling stability. The zinc-iodine batteries deliver a high capacity of 180 mAh g-1 at 1C and a stable cycle life over 3000 cycles with ~90% capacity retention as well as negligible self-discharge. We believe the principles for stabilizing the zinc-iodine system could provide new insight into conversion systems such as Li-S systems.

  7. Characterization of Aerodynamic Interactions with the Mars Science Laboratory Reaction Control System Using Computation and Experiment

    Science.gov (United States)

    Schoenenberger, Mark; VanNorman, John; Rhode, Matthew; Paulson, John

    2013-01-01

    On August 5 , 2012, the Mars Science Laboratory (MSL) entry capsule successfully entered Mars' atmosphere and landed the Curiosity rover in Gale Crater. The capsule used a reaction control system (RCS) consisting of four pairs of hydrazine thrusters to fly a guided entry. The RCS provided bank control to fly along a flight path commanded by an onboard computer and also damped unwanted rates due to atmospheric disturbances and any dynamic instabilities of the capsule. A preliminary assessment of the MSL's flight data from entry showed that the capsule flew much as predicted. This paper will describe how the MSL aerodynamics team used engineering analyses, computational codes and wind tunnel testing in concert to develop the RCS system and certify it for flight. Over the course of MSL's development, the RCS configuration underwent a number of design iterations to accommodate mechanical constraints, aeroheating concerns and excessive aero/RCS interactions. A brief overview of the MSL RCS configuration design evolution is provided. Then, a brief description is presented of how the computational predictions of RCS jet interactions were validated. The primary work to certify that the RCS interactions were acceptable for flight was centered on validating computational predictions at hypersonic speeds. A comparison of computational fluid dynamics (CFD) predictions to wind tunnel force and moment data gathered in the NASA Langley 31-Inch Mach 10 Tunnel was the lynch pin to validating the CFD codes used to predict aero/RCS interactions. Using the CFD predictions and experimental data, an interaction model was developed for Monte Carlo analyses using 6-degree-of-freedom trajectory simulation. The interaction model used in the flight simulation is presented.

  8. Field and laboratory emission cell automation and control system for investigating surface chemistry reactions

    Science.gov (United States)

    Flemmer, Michael M.; Ham, Jason E.; Wells, J. R.

    2007-01-01

    A novel system [field and laboratory emission cell (FLEC) automation and control system] has been developed to deliver ozone to a surface utilizing the FLEC to simulate indoor surface chemistry. Ozone, humidity, and air flow rate to the surface were continuously monitored using an ultraviolet ozone monitor, humidity, and flow sensors. Data from these sensors were used as feedback for system control to maintain predetermined experimental parameters. The system was used to investigate the chemistry of ozone with α-terpineol on a vinyl surface over 72h. Keeping all other experimental parameters the same, volatile organic compound emissions from the vinyl tile with α-terpineol were collected from both zero and 100ppb(partsper109) ozone exposures. System stability profiles collected from sensor data indicated experimental parameters were maintained to within a few percent of initial settings. Ozone data from eight experiments at 100ppb (over 339h) provided a pooled standard deviation of 1.65ppb and a 95% tolerance of 3.3ppb. Humidity data from 17 experiments at 50% relative humidity (over 664h) provided a pooled standard deviation of 1.38% and a 95% tolerance of 2.77%. Data of the flow rate of air flowing through the FLEC from 14 experiments at 300ml/min (over 548h) provided a pooled standard deviation of 3.02ml/min and a 95% tolerance range of 6.03ml/min. Initial experimental results yielded long term emissions of ozone/α-terpineol reaction products, suggesting that surface chemistry could play an important role in indoor environments.

  9. Method and device for thermal control of biological and chemical reactions using magnetic particles or magnetic beads and variable magnetic fields

    OpenAIRE

    Zilch, C.; Gerdes, W.; Bauer, J.; Holschuh, K.

    2009-01-01

    The invention relates to a method for the thermal control of at least one temperature-dependent enzymatic reaction in the presence of magnetic particles, particularly nanoparticles, or magnetic beads, in vitro by heating the magnetic beads or magnetic particles to at least one defined target temperature using alternating magnetic fields. The thermally controllable enzymatic reaction carried out with the method according to the invention is preferably a PCR reaction or another reaction for elo...

  10. Control rod effects on reaction rate distributions in tight pitched PuO2-UO2 fuel assembly

    International Nuclear Information System (INIS)

    Gil, Choong-Sup; Okumura, Keisuke; Ishiguro, Yukio

    1991-11-01

    Investigations were made for the heterogeneity effects caused by insertion or withdrawal of a B 4 C control rod on fine structure of reaction rates distributions in a tight pitched PuO 2 -UO 2 fuel assembly. Analysis was carried out by using the VIM and SRAC codes with the libraries based on JENDL-2 for the hexagonal fuel assembly basically corresponding to the PROTEUS-LWHCR experimental core. The reaction rates are affected more remarkably by the withdrawal of the control rod rather than its insertion. The changes of the reaction rates were decomposed into three terms of spectrum shifts, the changes of effective cross sections with fine groups, and their higher order components. From the analysis, it is concluded that most changes of reaction rates are caused by spectral shifts. The SRAC code with fine group constants can predict the distribution of reaction rates and their ratios with the accuracy of about 5 % except for the values related to Pu-242 capture rate, as compared with the VIM results. To increase the accuracy, it is necessary to generate the effective cross sections of the fuel near control rods with consideration of the heterogeneities in the fuel assembly. (author)

  11. Selecting a software development methodology. [of digital flight control systems

    Science.gov (United States)

    Jones, R. E.

    1981-01-01

    The state of the art analytical techniques for the development and verification of digital flight control software is studied and a practical designer oriented development and verification methodology is produced. The effectiveness of the analytic techniques chosen for the development and verification methodology are assessed both technically and financially. Technical assessments analyze the error preventing and detecting capabilities of the chosen technique in all of the pertinent software development phases. Financial assessments describe the cost impact of using the techniques, specifically, the cost of implementing and applying the techniques as well as the relizable cost savings. Both the technical and financial assessment are quantitative where possible. In the case of techniques which cannot be quantitatively assessed, qualitative judgements are expressed about the effectiveness and cost of the techniques. The reasons why quantitative assessments are not possible will be documented.

  12. Evaluation of completeness of selected poison control center data fields.

    Science.gov (United States)

    Jaramillo, Jeanie E; Marchbanks, Brenda; Willis, Branch; Forrester, Mathias B

    2010-08-01

    Poison control center data are used in research and surveillance. Due to the large volume of information, these efforts are dependent on data being recorded in machine readable format. However, poison center records include non-machine readable text fields and machine readable coded fields, some of which are duplicative. Duplicating this data increases the chance of inaccurate/incomplete coding. For surveillance efforts to be effective, coding should be complete and accurate. Investigators identified a convenience sample of 964 records and reviewed the substance code determining if it matched its text field. They also reviewed the coded clinical effects and treatments determining if they matched the notes text field. The substance code matched its text field for 91.4% of the substances. The clinical effects and treatments codes matched their text field for 72.6% and 82.4% of occurrences respectively. This under-reporting of clinical effects and treatments has surveillance and public health implications.

  13. Controlled formation of Ni(DMG)2 microrods/tubes by manipulating the kinetics of chemical reactions and their application in naked-eye sensors.

    Science.gov (United States)

    Qin, Jianli; Wang, Bo; Zhang, Xiujuan; Zhang, Xiaohong

    2012-08-01

    We have demonstrated controlled preparation of Ni(DMG)2 microrods/tubes via chemical reaction method. By manipulating the reaction kinetics via the concentration of reactants, shapes of the resulting microstructures can be easily tuned from microrods to microtubes. Size of the resulting products can also be controlled through changing the reaction temperatures. It was proposed that under high reactants' concentrations, molecules will prefer to grow at corners or edges of nuclei with high free energies, to reduce the total energy in the system, which would lead to partial or complete hollow interiors and eventually resulted in mircotubes. The fact that DMG show high selectivity with Ni2+ and accompanied with obvious color change enable us to fabricate test strip for naked-eye detection of Ni2+. Benefit from the large surface areas of DMG nanoparticles on the test strip, the detection limit is improved by two orders over that of conventional solution method. This strategy is sensitive, simple and easy to handle, thus expected to possess potentials for the practical Ni2+ detection applications.

  14. Suicide Survivors' Mental Health and Grief Reactions: A Systematic Review of Controlled Studies

    Science.gov (United States)

    Sveen, Carl-Aksel; Walby, Fredrik A.

    2008-01-01

    There has been a debate over several decades whether suicide survivors experience more severe mental health consequences and grief reactions than those who have been bereaved through other causes of death. This is the first systematic review of suicide survivors' reactions compared with survivors after other modes of death. Studies were identified…

  15. Longitudinal relations among parents' reactions to children's negative emotions, effortful control, and math achievement in early elementary school.

    Science.gov (United States)

    Swanson, Jodi; Valiente, Carlos; Lemery-Chalfant, Kathryn; Bradley, Robert H; Eggum-Wilkens, Natalie D

    2014-01-01

    Panel mediation models and fixed-effects models were used to explore longitudinal relations among parents' reactions to children's displays of negative emotions, children's effortful control (EC), and children's math achievement (N = 291; M age in fall of kindergarten = 5.66 years, SD = .39 year) across kindergarten through second grade. Parents reported their reactions and children's EC. Math achievement was assessed with a standardized achievement test. First-grade EC mediated the relation between parents' reactions at kindergarten and second-grade math achievement, beyond stability in constructs across study years. Panel mediation model results suggested that socialization of EC may be one method of promoting math achievement in early school; however, when all omitted time-invariant covariates of EC and math achievement were controlled, first-grade EC no longer predicted second-grade math achievement. © 2014 The Authors. Child Development © 2014 Society for Research in Child Development, Inc.

  16. Tailoring galvanic replacement reaction for the preparation of Pt/Ag bimetallic hollow nanostructures with controlled number of voids.

    Science.gov (United States)

    Zhang, Weiqing; Yang, Jizheng; Lu, Xianmao

    2012-08-28

    Here we report the synthesis of Pt/Ag bimetallic nanostructures with controlled number of void spaces via a tailored galvanic replacement reaction (GRR). Ag nanocubes (NCs) were employed as the template to react with Pt ions in the presence of HCl. The use of HCl in the GRR caused rapid precipitation of AgCl, which grew on the surface of Ag NCs and acted as a removable secondary template for the deposition of Pt. The number of nucleation sites for AgCl was tailored by controlling the amount of HCl added to the Ag NCs or by introducing PVP to the reaction. This strategy led to the formation of Pt/Ag hollow nanoboxes, dimers, multimers, or popcorn-shaped nanostructures consisting of one, two, or multiple hollow domains. Due to the presence of large void space and porous walls, these nanostructures exhibited high surface area and improved catalytic activity for methanol oxidation reaction.

  17. The major/minor concept: dependence of the selectivity of homogeneously catalyzed reactions on reactivity ratio and concentration ratio of the intermediates.

    Science.gov (United States)

    Schmidt, Thomas; Dai, Zhenya; Drexler, Hans-Joachim; Hapke, Marko; Preetz, Angelika; Heller, Detlef

    2008-07-07

    The homogeneously catalyzed asymmetric hydrogenation of prochiral olefins with cationic Rh(I) complexes is one of the best-understood selection processes. For some of the catalyst/substrate complexes, experimental proof points out the validation of the major/minor principle; the concentration-deficient minor substrate complex, which has very high reactivity, yields the excess enantiomer. As exemplified by the reaction system of [Rh(dipamp)(MeOH)2]+/methyl (Z)-alpha-acetamidocinnamate (dipamp=1,2-bis((o-methoxyphenyl)phenylphosphino)ethane), all six of the characteristic reaction rate constants have been previously identified. Recently, it was found that the major substrate complex can also yield the major enantiomer (lock-and-key principle). The differential equation system that results from the reaction sequence can be solved numerically for different hydrogen partial pressures by including the known equilibrium constants. The result displays the concentration-time dependence of all species that exist in the catalytic cycle. On the basis of the known constants as well as further experimental evidence, this work focuses on the examination of all principal possibilities resulting from the reaction sequence and leading to different results for the stereochemical outcome. From the simulation, the following conclusions can be drawn: 1) When an intermediate has extreme reactivity, its stationary concentration can become so small that it can no longer be the source of product selectivity; 2) in principle, the major/minor and lock-and-key principles can coexist depending on the applied pressure; 3) thermodynamically determined intermediate ratios can be completely converted under reaction conditions for a selection process; and 4) the increase in enantioselectivity with increasing hydrogen partial pressure, a phenomenon that is experimentally proven but theoretically far from being well-understood, can be explained by applying both the lock-and-key as well as the major

  18. Ikaros controls isotype selection during immunoglobulin class switch recombination.

    Science.gov (United States)

    Sellars, MacLean; Reina-San-Martin, Bernardo; Kastner, Philippe; Chan, Susan

    2009-05-11

    Class switch recombination (CSR) allows the humoral immune response to exploit different effector pathways through specific secondary antibody isotypes. However, the molecular mechanisms and factors that control immunoglobulin (Ig) isotype choice for CSR are unclear. We report that deficiency for the Ikaros transcription factor results in increased and ectopic CSR to IgG(2b) and IgG(2a), and reduced CSR to all other isotypes, regardless of stimulation. Ikaros suppresses active chromatin marks, transcription, and activation-induced cytidine deaminase (AID) accessibility at the gamma2b and gamma2a genes to inhibit class switching to these isotypes. Further, Ikaros directly regulates isotype gene transcription as it directly binds the Igh 3' enhancer and interacts with isotype gene promoters. Finally, Ikaros-mediated repression of gamma2b and gamma2a transcription promotes switching to other isotype genes by allowing them to compete for AID-mediated recombination at the single-cell level. Thus, our results reveal transcriptional competition between constant region genes in individual cells to be a critical and general mechanism for isotype specification during CSR. We show that Ikaros is a master regulator of this competition.

  19. National HIV prevalence estimates for sub-Saharan Africa: controlling selection bias with Heckman-type selection models

    Science.gov (United States)

    Hogan, Daniel R; Salomon, Joshua A; Canning, David; Hammitt, James K; Zaslavsky, Alan M; Bärnighausen, Till

    2012-01-01

    Objectives Population-based HIV testing surveys have become central to deriving estimates of national HIV prevalence in sub-Saharan Africa. However, limited participation in these surveys can lead to selection bias. We control for selection bias in national HIV prevalence estimates using a novel approach, which unlike conventional imputation can account for selection on unobserved factors. Methods For 12 Demographic and Health Surveys conducted from 2001 to 2009 (N=138 300), we predict HIV status among those missing a valid HIV test with Heckman-type selection models, which allow for correlation between infection status and participation in survey HIV testing. We compare these estimates with conventional ones and introduce a simulation procedure that incorporates regression model parameter uncertainty into confidence intervals. Results Selection model point estimates of national HIV prevalence were greater than unadjusted estimates for 10 of 12 surveys for men and 11 of 12 surveys for women, and were also greater than the majority of estimates obtained from conventional imputation, with significantly higher HIV prevalence estimates for men in Cote d'Ivoire 2005, Mali 2006 and Zambia 2007. Accounting for selective non-participation yielded 95% confidence intervals around HIV prevalence estimates that are wider than those obtained with conventional imputation by an average factor of 4.5. Conclusions Our analysis indicates that national HIV prevalence estimates for many countries in sub-Saharan African are more uncertain than previously thought, and may be underestimated in several cases, underscoring the need for increasing participation in HIV surveys. Heckman-type selection models should be included in the set of tools used for routine estimation of HIV prevalence. PMID:23172342

  20. Temperature Dependences for the Reactions of O2- and O- with N and O Atoms in a Selected-Ion Flow Tube Instrument

    Science.gov (United States)

    2013-10-07

    quadrupole mass filter, mass selected, and injected into the flow reactor via a Venturi - type inlet. Ions undergo ∼105 collisions with helium buffer... gas at pressures of 0.4 to 0.8 Torr resulting in complete or near-complete thermalization.10 The higher pressure was used when studying the high...butterfly gate valve resulting in lower pumping speeds and thus longer reaction times. Neutrals were injected 49 cm before the end of the flow tube and

  1. Controlled growth of gold nanoparticles in zeolite L via ion-exchange reactions and thermal reduction processes

    KAUST Repository

    Zeng, Shangjing

    2014-09-01

    The growth of gold nanoparticles in zeolite can be controlled using ion-exchange reactions and thermal reduction processes. We produce a number of different sizes of the gold nanoparticles with the particle size increasing with increased temperature of the final heat treatment. © 2014 Elsevier B.V.

  2. Irreversible endo-Selective Diels–Alder Reactions of Substituted Alkoxyfurans: A General Synthesis of endo-Cantharimides

    Science.gov (United States)

    Foster, Robert W; Benhamou, Laure; Porter, Michael J; Bučar, Dejan-Krešimir; Hailes, Helen C; Tame, Christopher J; Sheppard, Tom D

    2015-01-01

    The [4+2] cycloaddition of 3-alkoxyfurans with N-substituted maleimides provides the first general route for preparing endo-cantharimides. Unlike the corresponding reaction with 3H furans, the reaction can tolerate a broad range of 2-substitued furans including alkyl, aromatic, and heteroaromatic groups. The cycloaddition products were converted into a range of cantharimide products with promising lead-like properties for medicinal chemistry programs. Furthermore, the electron-rich furans are shown to react with a variety of alternative dienophiles to generate 7-oxabicyclo[2.2.1]heptane derivatives under mild conditions. DFT calculations have been performed to rationalize the activation effect of the 3-alkoxy group on a furan Diels–Alder reaction. PMID:25756502

  3. A survey of selected neutron-activation reactions with short-lived products of importance to fusion reactor technology

    International Nuclear Information System (INIS)

    Ward, R.C.; Gomes, I.C.; Smith, D.L.

    1994-11-01

    The status of the cross sections for production of short-lived radioactivities in the intense high-energy neutron fields associated with D-T fusion reactors is investigated. The main concerns relative to these very radioactive isotopes are with radiation damage to sensitive components such as superconducting magnets, the decay-heat problem and the safety of personnel during operation of the facility. The present report surveys the status of nuclear data required to assess these problems. The study is limited to a few high-priority nuclear reactions which appear to be of critical concern in this context. Other reactions of lesser concern are listed but are not treated in the present work. Among the factors that were considered in defining the relevant reactions and setting priorities are: quantities of the elemental materials in a fusion reactor, isotopic abundances within elemental categories, the decay properties of the induced radioactive byproducts, the reaction cross sections, and the nature of the decay radiations. Attention has been focused on radioactive species with half lives in the range from about 1 second to 15 minutes. Available cross-section and reaction-product decay information from the literature has been compiled and included in the report. Uncertainties have been estimated by examining several sets of experimental as well as evaluated data. Comments on the general status of data for various high-priority reactions are offered. On the basis of this investigation, it has been found that the nuclear data are in reasonably good shape for some of the most important reactions but are unacceptable for others. Based on this investigation, the reactions which should be given the greatest attention are: 16 O(n,p) 16 N, 55 Mn(n,p) 55 Cr, 57 Fe(n,p) 57 Mn, 186 W(n,2n) 185m W, and 207 Pb(n,n') 207m Pb. However, the development of fusion power would benefit from an across-the-board refinement in these nuclear data so that a more accurate quantitative

  4. Identification of selected in vitro generated phase-I metabolites of the steroidal selective androgen receptor modulator MK-0773 for doping control purposes.

    Science.gov (United States)

    Lagojda, Andreas; Kuehne, Dirk; Krug, Oliver; Thomas, Andreas; Wigger, Tina; Karst, Uwe; Schänzer, Wilhelm; Thevis, Mario

    2016-01-01

    Research into developing anabolic agents for various therapeutic purposes has been pursued for decades. As the clinical utility of anabolic-androgenic steroids has been found to be limited because of their lack of tissue selectivity and associated off-target effects, alternative drug entities have been designed and are commonly referred to as selective androgen receptor modulators (SARMs). While most of these SARMs are of nonsteroidal structure, the drug candidate MK-0773 comprises a 4-aza-steroidal nucleus. Besides the intended therapeutic use, SARMs have been found to be illicitly distributed and misused as doping agents in sport, necessitating frequently updated doping control analytical assays. As steroidal compounds reportedly undergo considerable metabolic transformations, the phase-I metabolism of MK-0773 was simulated using human liver microsomal (HLM) preparations and electrochemical conversion. Subsequently, major metabolic products were identified and characterized employing liquid chromatography-high-resolution/high- accuracy tandem mass spectrometry with electrospray (ESI) and atmospheric pressure chemical ionization (APCI) as well as nuclear magnetic resonance (NMR) spectroscopy. MK-0773 produced numerous phase-I metabolites under the chosen in vitro incubation reactions, mostly resulting from mono- and bisoxygenation of the steroid. HLM yielded at least 10 monooxygenated species, while electrochemistry-based experiments resulted predominantly in three monohydroxylated metabolites. Elemental composition data and product ion mass spectra were generated for these analytes, ESI/APCI measurements corroborated the formation of at least two N-oxygenated metabolites, and NMR data obtained from electrochemistry-derived products supported structures suggested for three monohydroxylated compounds. Hereby, the hydroxylation of the A-ring located N- bound methyl group was found to be of particular intensity. In the absence of controlled elimination studies, the

  5. Selection, integration, and conflict monitoring; assessing the nature and generality of prefrontal cognitive control mechanisms.

    Science.gov (United States)

    Badre, David; Wagner, Anthony D

    2004-02-05

    Prefrontal cortex (PFC) supports flexible behavior by mediating cognitive control, though the elemental forms of control supported by PFC remain a central debate. Dorsolateral PFC (DLPFC) is thought to guide response selection under conditions of response conflict or, alternatively, may refresh recently active representations within working memory. Lateral frontopolar cortex (FPC) may also adjudicate response conflict, though others propose that FPC supports higher order control processes such as subgoaling and integration. Anterior cingulate cortex (ACC) is hypothesized to upregulate response selection by detecting response conflict; it remains unclear whether ACC functions generalize beyond monitoring response conflict. The present fMRI experiment directly tested these competing theories regarding the functional roles of DLPFC, FPC, and ACC. Results reveal dissociable control processes in PFC, with mid-DLPFC selectively mediating resolution of response conflict and FPC further mediating subgoaling/integration. ACC demonstrated a broad sensitivity to control demands, suggesting a generalized role in modulating cognitive control.

  6. Optimal control of the initiation of a pericyclic reaction in the ...

    Indian Academy of Sciences (India)

    Abstract. Pericyclic reactions in the electronic ground state may be initiated by down-chirped pump-dump ... Figure 1. Cope rearrangement of semibullvalene, with pincer-motion-type ... investigations which have centred attention on the simp-.

  7. The reaction of hydroxylamine with bacteriorhodopsin studied with mutants that have altered photocycles: selective reactivity of different photointermediates.

    Science.gov (United States)

    Subramaniam, S; Marti, T; Rösselet, S J; Rothschild, K J; Khorana, H G

    1991-01-01

    The reaction of the retinylidene Schiff base in bacteriorhodopsin (bR) to the water-soluble reagent hydroxylamine is enhanced by greater than 2 orders of magnitude under illumination. We have used this reaction as a probe for changes in Schiff base reactivity during the photocycle of wild-type bR and mutants defective in proton transport. We report here that under illumination at pH 6, the D85N mutant has a 20-fold lower rate and the D212N mutant has a greater than 4-fold higher rate for the light-dependent reaction with hydroxylamine compared with wild-type bR. In contrast, the reactivities of wild-type bR and the D96N and T46V mutants are similar. It has been previously shown that the D96N and T46V replacements have no significant effect on the kinetics of "M" formation but have dramatic effects on rate of the decay of M. We therefore conclude that the hydroxylamine reaction occurs before formation of the M intermediate. Most likely it occurs at the "L" stage of the cycle and reflects increased water accessibility to the Schiff base due to a light-driven change in protein conformation. PMID:2006195

  8. Selective oxidations in microstructured catalytic reactions - A review and an overview of own work on fuel processing for fuel cells

    NARCIS (Netherlands)

    Hessel, V.; Kolb, G.A.; Cominos, V.; Loewe, H.; Nikolaidis, G.; Zapf, R.; Ziogas, A.; Schouten, J.C.; Delsman, E.R.; Croon, de M.H.J.M.; Santamaria, J.; Iglesia, de la O.; Mallada, R.

    2006-01-01

    This review is concerned about catalytic gas-phase oxidation reactions in microreactors, typically being performed in wall-coated microchannels. Not included are liquid and gas-liquid oxidations which are typically done in reactor designs different from the ones considered here. The first part of

  9. Non-Toxic Orbiter Maneuvering System (OMS) and Reaction Control System

    Science.gov (United States)

    Hurlbert, Eric A.; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    NASA is pursuing the technology and advanced development of a non-toxic (NT) orbital maneuvering system (OMS) and reaction control system (RCS) for shuttle upgrades, RLV, and reusable first stages. The primary objectives of the shuttle upgrades program are improved safety, improved reliability, reduced operations time and cost, improved performance or capabilities, and commonality with future space exploration needs. Non-Toxic OMS/RCS offers advantages in each of these categories. A non-toxic OMS/RCS eliminates the ground hazards and the flight safety hazards of the toxic and corrosive propellants. The cost savings for ground operations are over $24M per year for 7 flights, and the savings increase with increasing flight rate up to $44M per year. The OMS/RCS serial processing time is reduced from 65 days to 13 days. The payload capability can be increased up to 5100 Ibms. The non-toxic OMS/RCS also provides improved space station reboost capability up to 20 nautical miles over the current toxic system of 14 nautical miles. A NT OMS/RCS represents a clear advancement in the SOA over MMH/NTO. Liquid oxygen and ethanol are clean burning, high-density propellants that provide a high degree of commonality with other spacecraft subsystems including life support, power, and thermal control, and with future human exploration and development of space missions. The simple and reliable pressure-fed design uses sub-cooled liquid oxygen at 250 to 350 psia, which allows a propellant to remain cryogenic for longer periods of time. The key technologies are thermal insulation and conditioning techniques are used to maintain the sub-cooling. Phase I successfully defined the system architecture, designed an integrated OMS/RCS propellant tank, analyzed the feed system, built and tested the 870 lbf RCS thrusters, and tested the 6000 lbf OMS engine. Phase 11 is currently being planned for the development and test of full-scale prototype of the system in 1999 and 2000

  10. COST OF SELECTIVE CATALYTIC REDUCTION (SCR) APPLICATION FOR NOX CONTROL ON COAL-FIRED BOILERS

    Science.gov (United States)

    The report provides a methodology for estimating budgetary costs associated with retrofit applications of selective catalytic reduction (SCR) technology on coal-fired boilers. SCR is a postcombustion nitrogen oxides (NOx) control technology capable of providing NOx reductions >90...

  11. Exposures and reactions to allergens among hairdressing apprentices and matched controls

    DEFF Research Database (Denmark)

    Bregnhøj, Anne; Søsted, Heidi; Menné, Torkil

    2011-01-01

    Early and extensive exposures to chemical substances such as are found in hair dyes, perfumes and nickel are known risk factors for allergic reactions. Hairdressing apprentices belong to a high-risk group, as they are exposed both occupationally and personally.......Early and extensive exposures to chemical substances such as are found in hair dyes, perfumes and nickel are known risk factors for allergic reactions. Hairdressing apprentices belong to a high-risk group, as they are exposed both occupationally and personally....

  12. Characterization of catalytic supports based in mixed oxides for control reactions of NO and N2O

    International Nuclear Information System (INIS)

    Garcia C, M.A.; Perez H, R.; Gomez C, A.; Diaz, G.

    1999-01-01

    The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were prepared by the Precipitation and Coprecipitation techniques. The catalytic supports Al 2 O 3 , La 2 O 3 and Al 2 O 3 -La 2 O 3 were characterized by several techniques to determine: texture (Bet), crystallinity (XRD), chemical composition (Sem)(Ftir) and it was evaluated their total acidity by reaction with 2-propanol. The investigation will be continued with the cobalt addition and this will be evaluated for its catalytic activity in control reactions of N O and N 2 O. (Author)

  13. Switches of stimulus tagging frequencies interact with the conflict-driven control of selective attention, but not with inhibitory control.

    Science.gov (United States)

    Scherbaum, Stefan; Frisch, Simon; Dshemuchadse, Maja

    2016-01-01

    Selective attention and its adaptation by cognitive control processes are considered a core aspect of goal-directed action. Often, selective attention is studied behaviorally with conflict tasks, but an emerging neuroscientific method for the study of selective attention is EEG frequency tagging. It applies different flicker frequencies to the stimuli of interest eliciting steady state visual evoked potentials (SSVEPs) in the EEG. These oscillating SSVEPs in the EEG allow tracing the allocation of selective attention to each tagged stimulus continuously over time. The present behavioral investigation points to an important caveat of using tagging frequencies: The flicker of stimuli not only produces a useful neuroscientific marker of selective attention, but interacts with the adaptation of selective attention itself. Our results indicate that RT patterns of adaptation after response conflict (so-called conflict adaptation) are reversed when flicker frequencies switch at once. However, this effect of frequency switches is specific to the adaptation by conflict-driven control processes, since we find no effects of frequency switches on inhibitory control processes after no-go trials. We discuss the theoretical implications of this finding and propose precautions that should be taken into account when studying conflict adaptation using frequency tagging in order to control for the described confounds. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. The Selection, Use, and Reporting of Control Variables in International Business Research

    DEFF Research Database (Denmark)

    Nielsen, Bo Bernhard; Raswant, Arpit

    2018-01-01

    This study explores the selection, use, and reporting of control variables in studies published in the leading international business (IB) research journals. We review a sample of 246 empirical studies published in the top five IB journals over the period 2012–2015 with particular emphasis...... on selection, use, and reporting of controls. Approximately 83% of studies included only half of what we consider Minimum Standard of Practice with regards to controls, whereas only 38% of the studies met the 75% threshold. We provide recommendations on how to effectively identify, use and report controls...

  15. Chronic alcohol exposure disrupts top-down control over basal ganglia action selection to produce habits.

    Science.gov (United States)

    Renteria, Rafael; Baltz, Emily T; Gremel, Christina M

    2018-01-15

    Addiction involves a predominance of habitual control mediated through action selection processes in dorsal striatum. Research has largely focused on neural mechanisms mediating a proposed progression from ventral to dorsal lateral striatal control in addiction. However, over reliance on habit striatal processes may also arise from reduced cortical input to striatum, thereby disrupting executive control over action selection. Here, we identify novel mechanisms through which chronic intermittent ethanol exposure and withdrawal (CIE) disrupts top-down control over goal-directed action selection processes to produce habits. We find CIE results in decreased excitability of orbital frontal cortex (OFC) excitatory circuits supporting goal-directed control, and, strikingly, selectively reduces OFC output to the direct output pathway in dorsal medial striatum. Increasing the activity of OFC circuits restores goal-directed control in CIE-exposed mice. Our findings show habitual control in alcohol dependence can arise through disrupted communication between top-down, goal-directed processes onto basal ganglia pathways controlling action selection.

  16. Selective polymerization catalysis: controlling the metal chain end group to prepare block copolyesters.

    Science.gov (United States)

    Zhu, Yunqing; Romain, Charles; Williams, Charlotte K

    2015-09-30

    Selective catalysis is used to prepare block copolyesters by combining ring-opening polymerization of lactones and ring-opening copolymerization of epoxides/anhydrides. By using a dizinc complex with mixtures of up to three different monomers and controlling the chemistry of the Zn-O(polymer chain) it is possible to select for a particular polymerization route and thereby control the composition of block copolyesters.

  17. Stereo-controlled synthesis of polyheterocycles via the diene-transmissive hetero-Diels-Alder reaction of β,γ-unsaturated α-keto esters.

    Science.gov (United States)

    Otani, Takashi; Tamai, Yumiko; Seki, Kazunori; Kikuchi, Tomohiro; Miyazawa, Taiichiro; Saito, Takao

    2015-06-07

    We describe the stereoselective synthesis of polyring-fused heterocyclic compounds based on diene-transmissive hetero-Diels-Alder reactions utilizing β,γ-unsaturated α-keto esters. This protocol involves the initial endo- or exo-selective Diels-Alder (DA) reactions with electron-rich dienophiles, methylenation of the ester carbonyl groups with the Tebbe reagent, and a stereoselective second DA reaction with electron-deficient dienophiles. The use of enantioselective DA reactions in the initial reaction enables access to chiral polyring-fused heterocyclic compounds with multiple chiral centres.

  18. Effects of regular Tai Chi practice and jogging on neuromuscular reaction during lateral postural control in older people.

    Science.gov (United States)

    Wang, Shao-Jun; Xu, Dong-Qing; Li, Jing-Xian

    2017-01-01

    This study examined the effects of regular Tai Chi practice and jogging on the neuromuscular activity of the trunk, hip, and ankle joint muscles of older people during lateral postural perturbation. A total of 42 older people participated in the study and formed the Tai Chi, jogging, and sedentary control groups. Electromyography signals were collected from the peroneus longus, anterior tibialis, gluteus medius, and erector spinae during unpredictable mediolateral perturbation. The Tai Chi group exhibited significantly faster latencies of the tibialis anterior and erector spinae than the control group. The jogging group showed a significantly shorter neuromuscular reaction time of the erector spinae than the control group. No significant difference was observed between the Tai Chi and jogging groups. Long-term regular Tai Chi practice enhanced the neuromuscular reaction of the erector spinae and tibialis anterior to lateral perturbation and will help timely posture correction when lateral postural distributions occur.

  19. TiO2/Bi2(BDC)3/BiOCl nanoparticles decorated ultrathin nanosheets with excellent photocatalytic reaction activity and selectivity

    International Nuclear Information System (INIS)

    Zhou, Shu-Mei; Ma, De-Kun; Cai, Ping; Chen, Wei; Huang, Shao-Ming

    2014-01-01

    Graphical abstract: TiO 2 /Bi 2 (BDC) 3 /BiOCl nanoparticles decorated ultrathin nanosheets showed excellent photocatalytic reaction activity and selectivity. - Highlights: • TiO 2 /Bi 2 (BDC) 3 /BiOCl nanoparticles decorated ultrathin nanosheets were synthesized through a facile hydrothermal process. • The products showed excellent photocatalytic activities for the degradation of various dyes. • The photocatalytic activities of the composite materials could be easily adjusted through tuning the content of TiO 2 . • TiO 2 /Bi 2 (BDC) 3 /BiOCl displayed obvious photocatalytic selectivity in mixed dyes systems of rhodamine B and eosin Y. - Abstract: Photocatalysts with excellent photocatalytic reaction activity and ideal selectivity are highly desirable for pollutants clearance and purification of targeted organics from a mixture. Continued efforts toward the goal, we here present a facile hydrothermal route to synthesize TiO 2 /Bi-benzenedicarboxylate/BiOCl nanoparticles decorated ultrathin nanosheets with a thickness less than 5 nm on a large scale. The as-synthesized products showed excellent photocatalytic activities for the degradation of various dyes such as rhodamine B, eosin Y and methylene blue in aqueous solution under visible light irradiation. The photocatalytic activities of TiO 2 /Bi-benzenedicarboxylate/BiOCl nanocomposites for the degradation of rhodamine B and eosin Y could be adjusted through tuning the content of TiO 2 . With increasing the amount of TiO 2 , the composites showed declining photocatalytic activities in decomposing of rhodamine B while on the contrary they displayed enhanced photocatalytic activities in decomposing of eosin Y. Interestingly, TiO 2 /Bi-benzenedicarboxylate/BiOCl composite nanosheets showed obvious photocatalytic selectivity in a mixed dyes system. The photocatalytic reaction and selectivity mechanisms of the nanocomposites for the degradation of the dyes were discussed on the basis of experimental results. The

  20. Development of protein biomarkers in cerebrospinal fluid for secondary progressive multiple sclerosis using selected reaction monitoring mass spectrometry (SRM-MS

    Directory of Open Access Journals (Sweden)

    Jia Yan

    2012-07-01

    Full Text Available Abstract Background Multiple sclerosis (MS is a chronic inflammatory disorder of the central nervous system (CNS. It involves damage to the myelin sheath surrounding axons and to the axons themselves. MS most often presents with a series of relapses and remissions but then evolves over a variable period of time into a slowly progressive form of neurological dysfunction termed secondary progressive MS (SPMS. The reasons for this change in clinical presentation are unclear. The absence of a diagnostic marker means that there is a lag time of several years before the diagnosis of SPMS can be established. At the same time, understanding the mechanisms that underlie SPMS is critical to the development of rational therapies for this untreatable stage of the disease. Results Using high performance liquid chromatography-coupled mass spectrometry (HPLC; we have established a highly specific and sensitive selected reaction monitoring (SRM assay. Our multiplexed SRM assay has facilitated the simultaneous detection of surrogate peptides originating from 26 proteins present in cerebrospinal fluid (CSF. Protein levels in CSF were generally ~200-fold lower than that in human sera. A limit of detection (LOD was determined to be as low as one femtomol. We processed and analysed CSF samples from a total of 22 patients with SPMS, 7 patients with SPMS treated with lamotrigine, 12 patients with non-inflammatory neurological disorders (NIND and 10 healthy controls (HC for the levels of these 26 selected potential protein biomarkers. Our SRM data found one protein showing significant difference between SPMS and HC, three proteins differing between SPMS and NIND, two proteins between NIND and HC, and 11 protein biomarkers showing significant difference between a lamotrigine-treated and untreated SPMS group. Principal component analysis (PCA revealed that these 26 proteins were correlated, and could be represented by four principal components. Overall, we established an

  1. Reactions of State-Selected Atomic Oxygen Ions O+(S-4, D-2, P-2) with Methane

    Czech Academy of Sciences Publication Activity Database

    de Miranda, B. C.; Romanzin, C.; Chefdeville, M.; Vuitton, V.; Žabka, Ján; Polášek, Miroslav; Alcaraz, C.

    2015-01-01

    Roč. 119, č. 23 (2015), s. 6082-6098 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA14-19693S; GA MŠk(CZ) LD14024 Institutional support: RVO:61388955 Keywords : CHARGE-TRANSFER REACTIONS * PHOTOELECTRON-PHOTOION COINCIDENCE * TRANSLATIONAL ENERGY-DEPENDENCE Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.883, year: 2015

  2. Size Controlled Synthesis of Tellurium Nanorices by Galvanic Displacement Reaction of Aluminum

    International Nuclear Information System (INIS)

    Wu, Tingjun; Myung, Lawrence Youngjae; Zhang, Miluo; Lee, Kyu-Hwan; Lee, Yeheun Laura; Lim, Hyo-Ryong; Kim, Bum Sung; Choa, Yong-Ho; Myung, Nosang V.

    2015-01-01

    ABSTRACT: Tellurium nanostructures were synthesized by galvanic displacement reaction (GDR) of aluminum in an alkaline solution containing TeO 3 2− ions. Due to negative redox potential of Al/AlO 2 − (i.e., −2.50 V vs. sat. Ag/AgCl), TeO 3 2− (+IV) can be reduced to Te 2 2− (-I) and Te 2− (-II), which resulted in the deposition of Te (0) nanostructures in the solution via chemical reaction between Te 2 2− or Te 2− and TeO 3 2− . The deposition mechanism led to the formation of unique “rice-like” nanostructures in the solution instead of branched structures on the substrate. The sharp tips of the “rice-like” nanostructures may be attributed to the high density of surface charges at the tips. The morphology, diameter and aspect ratio of Te “rice-like” nanostructures were altered by the TeO 3 2− concentration, solution pH, reaction time and the reaction temperature. Electrochemical analytical methods, including open circuit potential (OCP) and linear polarizations (LPs), were used to investigate the reaction mechanisms. The enhancement of piezoelectric constant (d 11 ) of nanorices at small diameter was probably due to a flexoelectric effect

  3. The efficiency of driving chemical reactions by a physical non-equilibrium is kinetically controlled.

    Science.gov (United States)

    Göppel, Tobias; Palyulin, Vladimir V; Gerland, Ulrich

    2016-07-27

    An out-of-equilibrium physical environment can drive chemical reactions into thermodynamically unfavorable regimes. Under prebiotic conditions such a coupling between physical and chemical non-equilibria may have enabled the spontaneous emergence of primitive evolutionary processes. Here, we study the coupling efficiency within a theoretical model that is inspired by recent laboratory experiments, but focuses on generic effects arising whenever reactant and product molecules have different transport coefficients in a flow-through system. In our model, the physical non-equilibrium is represented by a drift-diffusion process, which is a valid coarse-grained description for the interplay between thermophoresis and convection, as well as for many other molecular transport processes. As a simple chemical reaction, we consider a reversible dimerization process, which is coupled to the transport process by different drift velocities for monomers and dimers. Within this minimal model, the coupling efficiency between the non-equilibrium transport process and the chemical reaction can be analyzed in all parameter regimes. The analysis shows that the efficiency depends strongly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics. Our model and results will be useful for a better understanding of the conditions for which non-equilibrium environments can provide a significant driving force for chemical reactions in a prebiotic setting.

  4. The application of selected radionuclides for monitoring of the D-D reactions produced by dense plasma-focus device.

    Science.gov (United States)

    Jednorog, S; Szydlowski, A; Bienkowska, B; Prokopowicz, R

    The dense plasma focus (DPF) device-DPF-1000U which is operated at the Institute of Plasma Physics and Laser Microfusion is the largest that type plasma experiment in the world. The plasma that is formed in large plasma experiments is characterized by vast numbers of parameters. All of them need to be monitored. A neutron activation method occupies a high position among others plasma diagnostic methods. The above method is off-line, remote, and an integrated one. The plasma which has enough temperature to bring about nuclear fusion reactions is always a strong source of neutrons that leave the reactions area and take along energy and important information on plasma parameters and properties as well. Silver as activated material is used as an effective way of neutrons measurement, especially when they are emitted in the form of short pulses like as it happens from the plasma produced in Dense Plasma-Focus devices. Other elements such as beryllium and yttrium are newly introduced and currently tested at the Institute of Plasma Physics and Laser Microfusion to use them in suitable activation neutron detectors. Some specially designed massive indium samples have been recently adopted for angular neutrons distribution measurements (vertical and horizontal) and have been used in the recent plasma experiment conducted on the DPF-1000U device. This choice was substantiated by relatively long half-lives of the neutron induced isotopes and the threshold character of the 115 In(n,n') 115m In nuclear reaction.

  5. Classical/quantum correspondence in state selective charge transfer and excitation reactions involving highly charged ions and hydrogen

    International Nuclear Information System (INIS)

    Purkait, M

    2009-01-01

    State selective charge transfer and excitation cross sections for collisions of Ne q+ (q = 1-10) with atomic hydrogen are calculated within the framework of Classical Trajectory Monte Carlo (CTMC) method and Boundary Corrected Continuum Intermediate State (BCCIS) approximation.

  6. Selecting measures to prevent deleterious alkali-silica reaction in concrete : rationale for the AASHTO PP65 prescriptive approach.

    Science.gov (United States)

    2012-10-01

    PP65-11 provides two approaches for selecting preventive measures: (i) a performance approach based on laboratory testing, and (ii) a prescriptive approach based on a consideration of the reactivity of the aggregate, type and size of structure, expos...

  7. Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization

    Directory of Open Access Journals (Sweden)

    Atsushi Narumi

    2018-06-01

    Full Text Available Macrocyclic polymers present an important class of macromolecules, displaying the reduced radius of gyration or impossibility to entangle. A rare approach for their synthesis is the ring expansion-controlled radical “vinyl” polymerization, starting from a cyclic alkoxyamine. We here describe ring-expansion radical crossover reactions of cyclic alkoxyamines which run in parallel to chain-propagation reactions in the polymerization system. The radical crossover reactions extensively occurred at 105–125 °C, eventually producing high molecular weight polymers with multiple inherent dynamic covalent bonds (NOC bonds. A subsequent ring-contraction radical crossover reaction and the second ring-expansion radical crossover reaction are also described. The major products for the respective three stages were shown to possess cyclic morphologies by the molecular weight profiles and the residual ratios for the NOC bonds (φ in %. In particular, the high φ values ranging from ca. 80% to 98% were achieved for this cyclic alkoxyamine system. This result verifies the high availability of this system as a tool demonstrating the ring-expansion “vinyl” polymerization that allows them to produce macrocyclic polymers via a one-step vinyl polymerization.

  8. On the Green's function of the partially diffusion-controlled reversible ABCD reaction for radiation chemistry codes

    International Nuclear Information System (INIS)

    Plante, Ianik; Devroye, Luc

    2015-01-01

    Several computer codes simulating chemical reactions in particles systems are based on the Green's functions of the diffusion equation (GFDE). Indeed, many types of chemical systems have been simulated using the exact GFDE, which has also become the gold standard for validating other theoretical models. In this work, a simulation algorithm is presented to sample the interparticle distance for partially diffusion-controlled reversible ABCD reaction. This algorithm is considered exact for 2-particles systems, is faster than conventional look-up tables and uses only a few kilobytes of memory. The simulation results obtained with this method are compared with those obtained with the independent reaction times (IRT) method. This work is part of our effort in developing models to understand the role of chemical reactions in the radiation effects on cells and tissues and may eventually be included in event-based models of space radiation risks. However, as many reactions are of this type in biological systems, this algorithm might play a pivotal role in future simulation programs not only in radiation chemistry, but also in the simulation of biochemical networks in time and space as well

  9. On the Green's function of the partially diffusion-controlled reversible ABCD reaction for radiation chemistry codes

    Energy Technology Data Exchange (ETDEWEB)

    Plante, Ianik, E-mail: ianik.plante-1@nasa.gov [Wyle Science, Technology & Engineering, 1290 Hercules, Houston, TX 77058 (United States); Devroye, Luc, E-mail: lucdevroye@gmail.com [School of Computer Science, McGill University, 3480 University Street, Montreal H3A 0E9 (Canada)

    2015-09-15

    Several computer codes simulating chemical reactions in particles systems are based on the Green's functions of the diffusion equation (GFDE). Indeed, many types of chemical systems have been simulated using the exact GFDE, which has also become the gold standard for validating other theoretical models. In this work, a simulation algorithm is presented to sample the interparticle distance for partially diffusion-controlled reversible ABCD reaction. This algorithm is considered exact for 2-particles systems, is faster than conventional look-up tables and uses only a few kilobytes of memory. The simulation results obtained with this method are compared with those obtained with the independent reaction times (IRT) method. This work is part of our effort in developing models to understand the role of chemical reactions in the radiation effects on cells and tissues and may eventually be included in event-based models of space radiation risks. However, as many reactions are of this type in biological systems, this algorithm might play a pivotal role in future simulation programs not only in radiation chemistry, but also in the simulation of biochemical networks in time and space as well.

  10. Invading stacking primer: A trigger for high-efficiency isothermal amplification reaction with superior selectivity for detecting microRNA variants.

    Science.gov (United States)

    Liu, Weipeng; Zhu, Minjun; Liu, Hongxing; Wei, Jitao; Zhou, Xiaoming; Xing, Da

    2016-07-15

    Searching for a strategy to enhance the efficiency of nucleic acid amplification and achieve exquisite discrimination of nucleic acids at the single-base level for biological detection has become an exciting research direction in recent years. Here, we have developed a simple and universal primer design strategy which produces a fascinating effect on isothermal strand displacement amplification (iSDA). We refer to the resultant primer as "invading stacking primer (IS-Primer)" which is based on contiguous stacking hybridization and toehold-mediated exchange reaction and function by merely changing the hybridization location of the primer. Using the IS-Primer, the sensitivity in detecting the target miR-21 is improved approximately five fold compared with the traditional iSDA reaction. It was further demonstrated that the IS-Primer acts as an invading strand to initiate branch migration which can increase the efficiency of the untwisting of the hairpin probe. This effect is equivalent to reducing the free energy of the stem, and the technique shows superior selectivity for single-base mismatches. By demonstrating the enhanced effect of the IS-Primer in the iSDA reaction, this work may provide a potentially new avenue for developing more sensitive and selective nucleic acids assays. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Selective C–C Coupling Reaction of Dimethylphenol to Tetramethyldiphenoquinone Using Molecular Oxygen Catalyzed by Cu Complexes Immobilized in Nanospaces of Structurally-Ordered Materials

    Directory of Open Access Journals (Sweden)

    Zen Maeno

    2015-02-01

    Full Text Available Two high-performance Cu catalysts were successfully developed by immobilization of Cu ions in the nanospaces of poly(propylene imine (PPI dendrimer and magadiite for the selective C–C coupling of 2,6-dimethylphenol (DMP to 3,3',5,5'-tetramethyldiphenoquinone (DPQ with O2 as a green oxidant. The PPI dendrimer encapsulated Cu ions in the internal nanovoids to form adjacent Cu species, which exhibited significantly high catalytic activity for the regioselective coupling reaction of DMP compared to previously reported enzyme and metal complex catalysts. The magadiite-immobilized Cu complex acted as a selective heterogeneous catalyst for the oxidative C–C coupling of DMP to DPQ. This heterogeneous catalyst was recoverable from the reaction mixture by simple filtration, reusable without loss of efficiency, and applicable to a continuous flow reactor system. Detailed characterization using ultraviolet-visible (UV-vis, Fourier transform infrared (FTIR, electronic spin resonance (ESR, and X-ray absorption fine structure (XAFS spectroscopies and the reaction mechanism investigation revealed that the high catalytic performances of these Cu catalysts were ascribed to the adjacent Cu species generated within the nanospaces of the PPI dendrimer and magadiite.

  12. Control of chemical reactions with electron beams; Kontrolle chemischer Reaktionen mit Elektronenstrahlung

    Energy Technology Data Exchange (ETDEWEB)

    Boehler, Esther

    2014-03-18

    Interaction between low-energy electrons and molecules can lead to dissociative electron attachment (DEA) or dissociative ionization (DI). In condensed matter, the resulting reactive fragments can attack adjacent molecules to yield larger products. In this thesis, reactions initiated by DEA to acetonitrile in condensed phase have been compared to the known gas phase fragmentation channels. Also, gas phase DEA experiments have been performed on chlorosilanes to study the effect of a variation of the organic ligands on the energy of their molecular orbitals and reactivity in DEA processes. Furthermore, hydroamination reactions induced by DI for different alkenes and amines have been investigated. A similar reaction of ammonia and carbon monoxide was shown to produce formamide (HCONH2), which is the smallest molecule to contain a peptide bond and thus represents an important building block of biologically relevant substances.

  13. Optimization of reaction conditions in selective oxidation of styrene over fine crystallite spinel-type CaFe2O4 complex oxide catalyst

    International Nuclear Information System (INIS)

    Pardeshi, Satish K.; Pawar, Ravindra Y.

    2010-01-01

    The CaFe 2 O 4 spinel-type catalyst was synthesized by citrate gel method and well characterized by thermogravimetric analysis, atomic absorption spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The crystallization temperature of the spinel particle prepared by citrate gel method was 600 o C which was lower than that of ferrite prepared by other methods. CaFe 2 O 4 catalysts prepared by citrate gel method show better activity for styrene oxidation in the presence of dilute H 2 O 2 (30%) as an oxidizing agent. In this reaction the oxidative cleavage of carbon-carbon double bond of styrene takes place selectively with 38 ± 2 mol% conversion. The major product of the reaction is benzaldehyde up to 91 ± 2 mol% and minor product phenyl acetaldehyde up to 9 ± 2 mol%, respectively. The products obtained in the styrene oxidation reaction were analyzed by gas chromatography and mass spectroscopy. The influence of the catalyst, reaction time, temperature, amount of catalyst, styrene/H 2 O 2 molar ratio and solvents on the conversion and product distribution were studied.

  14. Controlling the photochemical reaction of an azastilbene derivative in water using a water-soluble pillar[6]arene.

    Science.gov (United States)

    Xia, Danyu; Wang, Pi; Shi, Bingbing

    2017-09-20

    Photochemistry plays an important role in our lives. It has also been a common tool in the laboratory to construct complicated systems from small molecules. Supramolecular chemistry provides an opportunity to solve some of the problems in controlling photochemical reactions via non-covalent interactions. By using confining media and weak interactions between the medium and the reactant molecule, the excited state behavior of molecules has been successfully manipulated. Pillararenes, a new class of macrocyclic hosts, have rarely been used in the field of photochemical investigations, such as the controlling of photo-induced reactions. Herein, we explore a synthetic macrocyclic host, a water-soluble pillar[6]arene, as a controlling tool to manipulate the photo-induced reactions (hydration) in water. A host-guest system in water based on a water-soluble pillar[6]arene and an azastilbene derivative, (E)-4,4'-dimethyl-4,4'-diazoniastilbene diiodide, has been constructed. Then this water-soluble pillar[6]arene was successfully employed to control the photohydration of the azastilbene derivative in water as a "protective agent".

  15. Externally controlled anisotropy in pattern-forming reaction-diffusion systems.

    Science.gov (United States)

    Escala, Dario M; Guiu-Souto, Jacobo; Muñuzuri, Alberto P

    2015-06-01

    The effect of centrifugal forces is analyzed in a pattern-forming reaction-diffusion system. Numerical simulations conducted on the appropriate extension of the Oregonator model for the Belousov-Zhabotinsky reaction show a great variety of dynamical behaviors in such a system. In general, the system exhibits an anisotropy that results in new types of patterns or in a global displacement of the previous one. We consider the effect of both constant and periodically modulated centrifugal forces on the different types of patterns that the system may exhibit. A detailed analysis of the patterns and behaviors observed for the different parameter values considered is presented here.

  16. Tests of selection in pooled case-control data: an empirical study.

    Science.gov (United States)

    Udpa, Nitin; Zhou, Dan; Haddad, Gabriel G; Bafna, Vineet

    2011-01-01

    For smaller organisms with faster breeding cycles, artificial selection can be used to create sub-populations with different phenotypic traits. Genetic tests can be employed to identify the causal markers for the phenotypes, as a precursor to engineering strains with a combination of traits. Traditional approaches involve analyzing crosses of inbred strains to test for co-segregation with genetic markers. Here we take advantage of cheaper next generation sequencing techniques to identify genetic signatures of adaptation to the selection constraints. Obtaining individual sequencing data is often unrealistic due to cost and sample issues, so we focus on pooled genomic data. We explore a series of statistical tests for selection using pooled case (under selection) and control populations. The tests generally capture skews in the scaled frequency spectrum of alleles in a region, which are indicative of a selective sweep. Extensive simulations are used to show that these approaches work well for a wide range of population divergence times and strong selective pressures. Control vs control simulations are used to determine an empirical False Positive Rate, and regions under selection are determined using a 1% FPR level. We show that pooling does not have a significant impact on statistical power. The tests are also robust to reasonable variations in several different parameters, including window size, base-calling error rate, and sequencing coverage. We then demonstrate the viability (and the challenges) of one of these methods in two independent Drosophila populations (Drosophila melanogaster) bred under selection for hypoxia and accelerated development, respectively. Testing for extreme hypoxia tolerance showed clear signals of selection, pointing to loci that are important for hypoxia adaptation. Overall, we outline a strategy for finding regions under selection using pooled sequences, then devise optimal tests for that strategy. The approaches show promise for

  17. An Investigation of Control among Parents of Selectively Mute, Anxious, and Non-Anxious Children

    Science.gov (United States)

    Edison, Shannon C.; Evans, Mary Ann; McHolm, Angela E.; Cunningham, Charles E.; Nowakowski, Matilda E.; Boyle, Michael; Schmidt, Louis A.

    2011-01-01

    The authors examined parent-child interactions among three groups: selectively mute, anxious, and non-anxious children in different contexts. The relation between parental control (granting autonomy and high power remarks), child factors (i.e., age, anxiety, verbal participation), and parent anxiety was investigated. Parental control varied by…

  18. Reference gene selection for quantitative reverse transcription-polymerase chain reaction normalization during in vitro adventitious rooting in Eucalyptus globulus Labill.

    Science.gov (United States)

    de Almeida, Márcia R; Ruedell, Carolina M; Ricachenevsky, Felipe K; Sperotto, Raul A; Pasquali, Giancarlo; Fett-Neto, Arthur G

    2010-09-20

    Eucalyptus globulus and its hybrids are very important for the cellulose and paper industry mainly due to their low lignin content and frost resistance. However, rooting of cuttings of this species is recalcitrant and exogenous auxin application is often necessary for good root development. To date one of the most accurate methods available for gene expression analysis is quantitative reverse transcription-polymerase chain reaction (qPCR); however, reliable use of this technique requires reference genes for normalization. There is no single reference gene that can be regarded as universal for all experiments and biological materials. Thus, the identification of reliable reference genes must be done for every species and experimental approach. The present study aimed at identifying suitable control genes for normalization of gene expression associated with adventitious rooting in E. globulus microcuttings. By the use of two distinct algorithms, geNorm and NormFinder, we have assessed gene expression stability of eleven candidate reference genes in E. globulus: 18S, ACT2, EF2, EUC12, H2B, IDH, SAND, TIP41, TUA, UBI and 33380. The candidate reference genes were evaluated in microccuttings rooted in vitro, in presence or absence of auxin, along six time-points spanning the process of adventitious rooting. Overall, the stability profiles of these genes determined with each one of the algorithms were very similar. Slight differences were observed in the most stable pair of genes indicated by each program: IDH and SAND for geNorm, and H2B and TUA for NormFinder. Both programs identified UBI and 18S as the most variable genes. To validate these results and select the most suitable reference genes, the expression profile of the ARGONAUTE1 gene was evaluated in relation to the most stable candidate genes indicated by each algorithm. Our study showed that expression stability varied between putative reference genes tested in E. globulus. Based on the AGO1 relative expression

  19. Control of sodium fires and sodium-water reactions in breeder reactors

    International Nuclear Information System (INIS)

    Foerster, K.; Ruloff, G.; Voss, J.

    1985-01-01

    The excellent neutronic and thermodynamic properties of sodium as a fast-reactor coolant are somewhat counterbalanced by its high oxygen affinity. Because incidents like sodium fires and sodium-water reactions cannot be absolutely excluded, their effects and preventive measures have to be investigated. Characteristics and counter-measures are discussed. (orig.) [de

  20. A controlled study on batted ball speed and available pitcher reaction time in slowpitch softball

    Science.gov (United States)

    McDowell, M; Ciocco, M

    2005-01-01

    Objectives: To investigate safety risks in slowpitch softball by conducting laboratory and experimental studies on the performance of high tech softball bats with polyurethane softballs. To compare the results with the recommended safety standards. Methods: ASTM standard compression testing of seven softball models was conducted. Using these seven softball models, bat/ball impact testing was performed using seven adult male softball players and six high tech softball bat models to determine mean batted ball speeds. Over 500 bat/ball impact measurements were recorded and analysed. Available pitcher reaction time was calculated from the mean batted ball speed measurements. Results: According to the United States Specialty Sports Association and the Amateur Softball Association, the maximum initial batted ball speed should be 137.2 km/h, which corresponds to a minimum pitcher reaction time of 0.420 second. These experiments produced mean batted ball speeds of 134.0–159.7 km/h, which correspond to available pitcher reaction times of 0.409–0.361 second. Conclusion: The use of high tech softball bats with polyurethane softballs can result in batted ball speeds that exceed the recommended safety limits, which correspond to decreased available pitcher reaction times. PMID:15793092

  1. Exposures and reactions to allergens among hairdressing apprentices and matched controls

    DEFF Research Database (Denmark)

    Bregnhøj, Anne; Søsted, Heidi; Menné, Torkil

    2011-01-01

    Early and extensive exposures to chemical substances such as are found in hair dyes, perfumes and nickel are known risk factors for allergic reactions. Hairdressing apprentices belong to a high-risk group, as they are exposed both occupationally and personally....

  2. Pre-Vaccination Care-Seeking in Females Reporting Severe Adverse Reactions to HPV Vaccine. A Registry Based Case-Control Study.

    Directory of Open Access Journals (Sweden)

    Kåre Mølbak

    Full Text Available Since 2013 the number of suspected adverse reactions to the quadrivalent human papillomavirus (HPV vaccine reported to the Danish Medicines Agency (DMA has increased. Due to the resulting public concerns about vaccine safety, the coverage of HPV vaccinations in the childhood vaccination programme has declined. The aim of the present study was to determine health care-seeking prior to the first HPV vaccination among females who suspected adverse reactions to HPV vaccine.In this registry-based case-control study, we included as cases vaccinated females with reports to the DMA of suspected severe adverse reactions. We selected controls without reports of adverse reactions from the Danish vaccination registry and matched by year of vaccination, age of vaccination, and municipality, and obtained from the Danish National Patient Registry and The National Health Insurance Service Register the history of health care usage two years prior to the first vaccine. We analysed the data by logistic regression while adjusting for the matching variables.The study included 316 cases who received first HPV vaccine between 2006 and 2014. Age range of cases was 11 to 52 years, with a peak at 12 years, corresponding to the recommended age at vaccination, and another peak at 19 to 28 years, corresponding to a catch-up programme targeting young women. Compared with 163,910 controls, cases had increased care-seeking in the two years before receiving the first HPV vaccine. A multivariable model showed higher use of telephone/email consultations (OR 1.9; 95% CI 1.2-3.2, physiotherapy (OR 2.1; 95% CI 1.6-2.8 and psychologist/psychiatrist (OR 1.9; 95% CI 1.3-2.7. Cases were more likely to have a diagnosis in the ICD-10 chapters of diseases of the digestive system (OR 1.6; 95% CI 1.0-2.4, of the musculoskeletal system (OR 1.6; 95% CI 1.1-2.2, symptoms or signs not classified elsewhere (OR 1.8; 95% CI 1.3-2.5 as well as injuries (OR 1.5; 95% CI 1.2-1.9.Before receiving the

  3. A randomised controlled trial of two infusion rates to decrease reactions to antivenom.

    Directory of Open Access Journals (Sweden)

    Geoffrey K Isbister

    Full Text Available BACKGROUND: Snake envenoming is a major clinical problem in Sri Lanka, with an estimated 40,000 bites annually. Antivenom is only available from India and there is a high rate of systemic hypersensitivity reactions. This study aimed to investigate whether the rate of infusion of antivenom reduced the frequency of severe systemic hypersensitivity reactions. METHODS AND FINDINGS: This was a randomized comparison trial of two infusion rates of antivenom for treatment of non-pregnant adult patients (>14 y with snake envenoming in Sri Lanka. Snake identification was by patient or hospital examination of dead snakes when available and confirmed by enzyme-immunoassay for Russell's viper envenoming. Patients were blindly allocated in a 11 randomisation schedule to receive antivenom either as a 20 minute infusion (rapid or a two hour infusion (slow. The primary outcome was the proportion with severe systemic hypersensitivity reactions (grade 3 by Brown grading system within 4 hours of commencement of antivenom. Secondary outcomes included the proportion with mild/moderate hypersensitivity reactions and repeat antivenom doses. Of 1004 patients with suspected snakebites, 247 patients received antivenom. 49 patients were excluded or not recruited leaving 104 patients allocated to the rapid antivenom infusion and 94 to the slow antivenom infusion. The median actual duration of antivenom infusion in the rapid group was 20 min (Interquartile range[IQR]:20-25 min versus 120 min (IQR:75-120 min in the slow group. There was no difference in severe systemic hypersensitivity reactions between those given rapid and slow infusions (32% vs. 35%; difference 3%; 95%CI:-10% to +17%;p = 0.65. The frequency of mild/moderate reactions was also similar. Similar numbers of patients in each arm received further doses of antivenom (30/104 vs. 23/94. CONCLUSIONS: A slower infusion rate would not reduce the rate of severe systemic hypersensitivity reactions from current high

  4. Ligand-Controlled Synthesis of Azoles via Ir-Catalyzed Reactions of Sulfoxonium Ylides with 2-Amino Heterocycles.

    Science.gov (United States)

    Phelps, Alicia M; Chan, Vincent S; Napolitano, José G; Krabbe, Scott W; Schomaker, Jennifer M; Shekhar, Shashank

    2016-05-20

    An iridium-catalyzed method was developed for the synthesis of imidazo-fused pyrrolopyrazines. The presence or absence of a nitrogenated ligand controlled the outcome of the reaction, leading to simple β-keto amine products in the absence of added ligand and the cyclized 7- and 8-substituted-imidazo[1,2-a]pyrrolo[2,3-e]pyrazine products in the presence of ligand. This catalyst control was conserved across a variety of ylide and amine coupling partners. The substrate was shown to act as a ligand for the iridium catalyst in the absence of other ligands via NMR spectroscopy. Kinetic studies indicated that formation of the Ir-carbene was reversible and the slow step of the reaction. These mechanistic investigations suggest that the β-keto amine products form via an intramolecular carbene N-H insertion, and the imidazopyrrolopyrazines form via an intermolecular carbene N-H insertion.

  5. Serologic reactions against Salmonella in samples from broiler parent stock with and without preceding colibacillosis: A case-control study

    DEFF Research Database (Denmark)

    Gradel, K.O.; Feld, Niels Christian; Andersen, J. S.

    2001-01-01

    In the Danish Salmonella Control Program, eggs from broiler parent flocks are surveyed by serologic analysis every 4 wk for antibodies against Salmonella lipopolysaccharide O-antigens 1, 4, 5, 9, and 12 (Mix-enzyme-linked immunosorbent assay [ELISA]) and 6 and 7 (Infantis-ELISA). The antibody...... response is measured in percentage optical density (OD%) of a strong positive reaction, and the cutoff value has been determined to be 40 OD%. Two or more reactors above 40 OD% will place the parent flock under suspicion. There has been concern about possible cross-reactions between Salmonella spp....... and other Enterobacteriaceae, e.g., Escherichia coli, because a high specificity of a Salmonella antibody test is desirable. Moreover, false-positive Salmonella results have economic consequences and impede planning the production. A case-control study based on cases of clinical E. coli infections...

  6. Selective detection of carbon-13, nitrogen-15, and deuterium labeled metabolites by capillary gas chromatography-chemical reaction interface/mass spectrometry

    International Nuclear Information System (INIS)

    Chace, D.H.; Abramson, F.P.

    1989-01-01

    We have applied a new chemical reaction interface/mass spectrometer technique (CRIMS) to the selective detection of 13C-, 15N-, and 2H-labeled phenytoin and its metabolites in urine following separation by capillary gas chromatography. The microwave-powered chemical reaction interface converts materials from their original forms into small molecules whose mass spectra serve to identify and quantify the nuclides that make up each analyte. The presence of each element is followed by monitoring the isotopic variants of CO2, NO, or H2 that are produced by the chemical reaction interface. Chromatograms showing only enriched 13C and 15N were produced by subtracting the abundance of naturally occurring isotopes from the observed M + 1 signal. A selective chromatogram of 2H (D) was obtained by measuring HD at m/z 3.0219 with a resolution of 2000. Metabolites representing less than 1.5% of the total labeled compounds could be identified in the chromatogram. Detection limits from urine of 380 pg/mL of a 15N-labeled metabolite, 7 ng/mL of a 13C-labeled metabolite, and 16 ng/mL of a deuterium labeled metabolite were determined at a signal to noise ratio of 2. Depending on the isotope examined, a linear dynamic range of 250-1000 was observed using CRIMS. To identify many of these labeled peaks (metabolites), the chromatographic analysis was repeated with the chemical reaction interface turned off and mass spectra obtained at the retention times found in the CRIMS experiment. CRIMS is a new analytical method that appears to be particularly useful for metabolism studies

  7. SeleCon: Scalable IoT Device Selection and Control Using Hand Gestures.

    Science.gov (United States)

    Alanwar, Amr; Alzantot, Moustafa; Ho, Bo-Jhang; Martin, Paul; Srivastava, Mani

    2017-04-01

    Although different interaction modalities have been proposed in the field of human-computer interface (HCI), only a few of these techniques could reach the end users because of scalability and usability issues. Given the popularity and the growing number of IoT devices, selecting one out of many devices becomes a hurdle in a typical smarthome environment. Therefore, an easy-to-learn, scalable, and non-intrusive interaction modality has to be explored. In this paper, we propose a pointing approach to interact with devices, as pointing is arguably a natural way for device selection. We introduce SeleCon for device selection and control which uses an ultra-wideband (UWB) equipped smartwatch. To interact with a device in our system, people can point to the device to select it then draw a hand gesture in the air to specify a control action. To this end, SeleCon employs inertial sensors for pointing gesture detection and a UWB transceiver for identifying the selected device from ranging measurements. Furthermore, SeleCon supports an alphabet of gestures that can be used for controlling the selected devices. We performed our experiment in a 9 m -by-10 m lab space with eight deployed devices. The results demonstrate that SeleCon can achieve 84.5% accuracy for device selection and 97% accuracy for hand gesture recognition. We also show that SeleCon is power efficient to sustain daily use by turning off the UWB transceiver, when a user's wrist is stationary.

  8. Channel selection for simultaneous and proportional myoelectric prosthesis control of multiple degrees-of-freedom

    Science.gov (United States)

    Hwang, Han-Jeong; Hahne, Janne Mathias; Müller, Klaus-Robert

    2014-10-01

    Objective. Recent studies have shown the possibility of simultaneous and proportional control of electrically powered upper-limb prostheses, but there has been little investigation on optimal channel selection. The objective of this study is to find a robust channel selection method and the channel subsets most suitable for simultaneous and proportional myoelectric prosthesis control of multiple degrees-of-freedom (DoFs). Approach. Ten able-bodied subjects and one person with congenital upper-limb deficiency took part in this study, and performed wrist movements with various combinations of two DoFs (flexion/extension and radial/ulnar deviation). During the experiment, high density electromyographic (EMG) signals and the actual wrist angles were recorded with an 8 × 24 electrode array and a motion tracking system, respectively. The wrist angles were estimated from EMG features with ridge regression using the subsets of channels chosen by three different channel selection methods: (1) least absolute shrinkage and selection operator (LASSO), (2) sequential feature selection (SFS), and (3) uniform selection (UNI). Main results. SFS generally showed higher estimation accuracy than LASSO and UNI, but LASSO always outperformed SFS in terms of robustness, such as noise addition, channel shift and training data reduction. It was also confirmed that about 95% of the original performance obtained using all channels can be retained with only 12 bipolar channels individually selected by LASSO and SFS. Significance. From the analysis results, it can be concluded that LASSO is a promising channel selection method for accurate simultaneous and proportional prosthesis control. We expect that our results will provide a useful guideline to select optimal channel subsets when developing clinical myoelectric prosthesis control systems based on continuous movements with multiple DoFs.

  9. AN ASSESSMENT OF FACTORS AFFECTING MATERIAL STOCK CONTROL PRACTICE ON SELECTED CONSTRUCTION SITES IN NIGERIA

    OpenAIRE

    Adafin, Johnson Kayode; Ayodele, Elijah Olusegun; Daramola, Olufemi

    2011-01-01

    This research examines the stock control methods utilized by construction firms on construction sites with a view to assessing the factors affecting material stock control practice by construction firms as well as determining the impact of factors affecting material stock control on building project performance. Data were collected with the aid of well-structured questionnaire administered on a number of construction professionals and technicians in some randomly selected building constructio...

  10. A framework for selecting suitable control technologies for nuclear power plant systems

    International Nuclear Information System (INIS)

    Kisner, R.A.

    1992-01-01

    New concepts continue to emerge for controlling systems, subsystems, and components and for monitoring parameters, characteristics, and vital signs in nuclear power plants. The steady stream of new control theories and the evolving state of control software exacerbates the difficulty of selecting the most appropriate control technology for nuclear power plant systems. As plant control room operators increase their reliance on computerized systems, the integration of monitoring, diagnostic, and control functions into a uniform and understandable environment becomes imperative. A systematic framework for comparing and evaluating the overall usefulness of control techniques is needed. This paper describes nine factors that may be used to evaluate alternative control concepts. These factors relate to a control system's potential effectiveness within the context of the overall environment, including both human and machine components. Although not an in-depth study, this paper serves to outline an evaluation framework based on several measures of utility. 32 refs

  11. Fast and selective determination of total protein in milk powder via titration of moving reaction boundary electrophoresis.

    Science.gov (United States)

    Guo, Cheng-ye; Wang, Hou-yu; Liu, Xiao-ping; Fan, Liu-yin; Zhang, Lei; Cao, Cheng-xi

    2013-05-01

    In this paper, moving reaction boundary titration (MRBT) was developed for rapid and accurate quantification of total protein in infant milk powder, from the concept of moving reaction boundary (MRB) electrophoresis. In the method, the MRB was formed by the hydroxide ions and the acidic residues of milk proteins immobilized via cross-linked polyacrylamide gel (PAG), an acid-base indicator was used to denote the boundary motion. As a proof of concept, we chose five brands of infant milk powders to study the feasibility of MRBT method. The calibration curve of MRB velocity versus logarithmic total protein content of infant milk powder sample was established based on the visual signal of MRB motion as a function of logarithmic milk protein content. Weak influence of nonprotein nitrogen (NPN) reagents (e.g., melamine and urea) on MRBT method was observed, due to the fact that MRB was formed with hydroxide ions and the acidic residues of captured milk proteins, rather than the alkaline residues or the NPN reagents added. The total protein contents in infant milk powder samples detected via the MRBT method were in good agreement with those achieved by the classic Kjeldahl method. In addition, the developed method had much faster measuring speed compared with the Kjeldahl method. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Fuzzy logic control for selective hydrogenation of acetylene in ethylene rich streams using visual basic

    International Nuclear Information System (INIS)

    Malik, S.R.; Suleman, H.; Khan, J.R.

    2010-01-01

    Presence of acetylene is technically disadvantageous in the ethylene rich gas streams from steam crackers. Acetylene tends to polymerize and inactivates the transition metal catalysts, forming highly explosive compounds. The acetylene content has to be selectively reduced to less than one part per million for such streams. The acetylene hydrogenation unit requires stringent control parameters and needs specialized process control techniques for its operation. This study is concerned with application of Fuzzy Logic Control to manipulate and control the process plant with higher precision and greater simplicity. The control program has been written in visual Basic and entails all major scenarios of work modes for successful hydrogenation of Acetylene. (author)

  13. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.

  14. Effects of manganese oxide and sulphate on the olefin selectivity of iron catalysts in the Fischer Tropsch reaction

    NARCIS (Netherlands)

    Dijk, van W.L.; Niemantsverdriet, J.W.; Kraan, van der A.M.; van der Baan, Hessel

    1982-01-01

    Although it has been claimed by various authors that the addition of manganese oxide, MnO, to an iron catalyst gives a marked increase in the olefin selectivity of iron catalysts, we have been unable to confirm these claims in Fischer Tropsch experiments at 513 K for an iron manganese oxide catalyst

  15. Distinct regions of prefrontal cortex are associated with the controlled retrieval and selection of social information.

    Science.gov (United States)

    Satpute, Ajay B; Badre, David; Ochsner, Kevin N

    2014-05-01

    Research in social neuroscience has uncovered a social knowledge network that is particularly attuned to making social judgments. However, the processes that are being performed by both regions within this network and those outside of this network that are nevertheless engaged in the service of making a social judgment remain unclear. To help address this, we drew upon research in semantic memory, which suggests that making a semantic judgment engages 2 distinct control processes: A controlled retrieval process, which aids in bringing goal-relevant information to mind from long-term stores, and a selection process, which aids in selecting the information that is goal-relevant from the information retrieved. In a neuroimaging study, we investigated whether controlled retrieval and selection for social information engage distinct portions of both the social knowledge network and regions outside this network. Controlled retrieval for social information engaged an anterior ventrolateral portion of the prefrontal cortex, whereas selection engaged both the dorsomedial prefrontal cortex and temporoparietal junction within the social knowledge network. These results suggest that the social knowledge network may be more involved with the selection of social information than the controlled retrieval of it and incorporates lateral prefrontal regions in accessing memory for making social judgments.

  16. Preparing to reach: selecting an adaptive long-latency feedback controller

    OpenAIRE

    Ahmadi-Pajouh, Mohammad Ali; Towhidkhah, Farzad; Shadmehr, Reza

    2012-01-01

    In a voluntary movement, the nervous system specifies not only the motor commands, but also the gains associated with reaction to sensory feedback. For example, suppose that during reaching a perturbation tends to push the hand to the left. With practice, the brain not only learns to produce commands that predictively compensate for the perturbation, but also increases the long-latency reflex gain associated with leftward displacements of the arm. That is, the brain learns a feedback controll...

  17. Contextual control over selective attention: evidence from a two-target method.

    Science.gov (United States)

    MacLellan, Ellen; Shore, David I; Milliken, Bruce

    2015-07-01

    Selective attention is generally studied with conflict tasks, using response time as the dependent measure. Here, we study the impact of selective attention to a first target, T1, presented simultaneously with a distractor, on the accuracy of subsequent encoding of a second target item, T2. This procedure produces an "attentional blink" (AB) effect much like that reported in other studies, and allowed us to study the influence of context on cognitive control with a novel method. In particular, we examined whether preparation to attend selectively to T1 had an impact on the selective encoding of T1 that would translate to report of T2. Preparation to attend selectively was manipulated by varying whether difficult selective attention T1 trials were presented in the context of other difficult selective attention T1 trials. The results revealed strong context effects of this nature, with smaller AB effects when difficult selective attention T1 trials were embedded in a context with many, rather than few, other difficult selective attention T1 trials. Further, the results suggest that both the trial-to-trial local context and the block-wide global context modulate performance in this task.

  18. A single residue controls electron transfer gating in photosynthetic reaction centers

    Czech Academy of Sciences Publication Activity Database

    Shlyk, O.; Samish, I.; Matěnová, M.; Dulebo, A.; Poláková, H.; Kaftan, David; Scherz, A.

    2017-01-01

    Roč. 7, MAR 16 (2017), s. 1-13, č. článku 44580. ISSN 2045-2322 R&D Projects: GA ČR GA15-00703S; GA MŠk(CZ) LO1416 Institutional support: RVO:61388971 Keywords : BACTERIAL REACTION CENTERS * INDUCED STRUCTURAL-CHANGES * ATOMIC-FORCE MICROSCOPE Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.259, year: 2016

  19. Simple Copper Catalysts for the Aerobic Oxidation of Amines: Selectivity Control by the Counterion.

    Science.gov (United States)

    Xu, Boran; Hartigan, Elizabeth M; Feula, Giancarlo; Huang, Zheng; Lumb, Jean-Philip; Arndtsen, Bruce A

    2016-12-19

    We describe the use of simple copper-salt catalysts in the selective aerobic oxidation of amines to nitriles or imines. These catalysts are marked by their exceptional efficiency, operate at ambient temperature and pressure, and allow the oxidation of amines without expensive ligands or additives. This study highlights the significant role counterions can play in controlling selectivity in catalytic aerobic oxidations. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. From Cellular Attractor Selection to Adaptive Signal Control for Traffic Networks.

    Science.gov (United States)

    Tian, Daxin; Zhou, Jianshan; Sheng, Zhengguo; Wang, Yunpeng; Ma, Jianming

    2016-03-14

    The management of varying traffic flows essentially depends on signal controls at intersections. However, design an optimal control that considers the dynamic nature of a traffic network and coordinates all intersections simultaneously in a centralized manner is computationally challenging. Inspired by the stable gene expressions of Escherichia coli in response to environmental changes, we explore the robustness and adaptability performance of signalized intersections by incorporating a biological mechanism in their control policies, specifically, the evolution of each intersection is induced by the dynamics governing an adaptive attractor selection in cells. We employ a mathematical model to capture such biological attractor selection and derive a generic, adaptive and distributed control algorithm which is capable of dynamically adapting signal operations for the entire dynamical traffic network. We show that the proposed scheme based on attractor selection can not only promote the balance of traffic loads on each link of the network but also allows the global network to accommodate dynamical traffic demands. Our work demonstrates the potential of bio-inspired intelligence emerging from cells and provides a deep understanding of adaptive attractor selection-based control formation that is useful to support the designs of adaptive optimization and control in other domains.

  1. Factors Controlling the Redox Activity of Oxygen in Perovskites: From Theory to Application for Catalytic Reactions

    Directory of Open Access Journals (Sweden)

    Chunzhen Yang

    2017-05-01

    Full Text Available Triggering the redox reaction of oxygens has become essential for the development of (electro catalytic properties of transition metal oxides, especially for perovskite materials that have been envisaged for a variety of applications such as the oxygen evolution or reduction reactions (OER and ORR, respectively, CO or hydrocarbons oxidation, NO reduction and others. While the formation of ligand hole for perovskites is well-known for solid state physicists and/or chemists and has been widely studied for the understanding of important electronic properties such as superconductivity, insulator-metal transitions, magnetoresistance, ferroelectrics, redox properties etc., oxygen electrocatalysis in aqueous media at low temperature barely scratches the surface of the concept of oxygen ions oxidation. In this review, we briefly explain the electronic structure of perovskite materials and go through a few important parameters such as the ionization potential, Madelung potential, and charge transfer energy that govern the oxidation of oxygen ions. We then describe the surface reactivity that can be induced by the redox activity of the oxygen network and the formation of highly reactive surface oxygen species before describing their participation in catalytic reactions and providing mechanistic insights and strategies for designing new (electro catalysts. Finally, we give a brief overview of the different techniques that can be employed to detect the formation of such transient oxygen species.

  2. A Study of Interactions between Mixing and Chemical Reaction Using the Rate-Controlled Constrained-Equilibrium Method

    Science.gov (United States)

    Hadi, Fatemeh; Janbozorgi, Mohammad; Sheikhi, M. Reza H.; Metghalchi, Hameed

    2016-10-01

    The rate-controlled constrained-equilibrium (RCCE) method is employed to study the interactions between mixing and chemical reaction. Considering that mixing can influence the RCCE state, the key objective is to assess the accuracy and numerical performance of the method in simulations involving both reaction and mixing. The RCCE formulation includes rate equations for constraint potentials, density and temperature, which allows taking account of mixing alongside chemical reaction without splitting. The RCCE is a dimension reduction method for chemical kinetics based on thermodynamics laws. It describes the time evolution of reacting systems using a series of constrained-equilibrium states determined by RCCE constraints. The full chemical composition at each state is obtained by maximizing the entropy subject to the instantaneous values of the constraints. The RCCE is applied to a spatially homogeneous constant pressure partially stirred reactor (PaSR) involving methane combustion in oxygen. Simulations are carried out over a wide range of initial temperatures and equivalence ratios. The chemical kinetics, comprised of 29 species and 133 reaction steps, is represented by 12 RCCE constraints. The RCCE predictions are compared with those obtained by direct integration of the same kinetics, termed detailed kinetics model (DKM). The RCCE shows accurate prediction of combustion in PaSR with different mixing intensities. The method also demonstrates reduced numerical stiffness and overall computational cost compared to DKM.

  3. Field-controlled electron transfer and reaction kinetics of the biological catalytic system of microperoxidase-11 and hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Yongki Choi

    2011-12-01

    Full Text Available Controlled reaction kinetics of the bio-catalytic system of microperoxidase-11 and hydrogen peroxide has been achieved using an electrostatic technique. The technique allowed independent control of 1 the thermodynamics of the system using electrochemical setup and 2 the quantum mechanical tunneling at the interface between microperoxidase-11 and the working electrode by applying a gating voltage to the electrode. The cathodic currents of electrodes immobilized with microperoxidase-11 showed a dependence on the gating voltage in the presence of hydrogen peroxide, indicating a controllable reduction reaction. The measured kinetic parameters of the bio-catalytic reduction showed nonlinear dependences on the gating voltage as the result of modified interfacial electron tunnel due to the field induced at the microperoxidase-11-electrode interface. Our results indicate that the kinetics of the reduction of hydrogen peroxide can be controlled by a gating voltage and illustrate the operation of a field-effect bio-catalytic transistor, whose current-generating mechanism is the conversion of hydrogen peroxide to water with the current being controlled by the gating voltage.

  4. Atomic Layer Control of Thin Film Growth Using Binary Reaction Sequence Chemistry

    National Research Council Canada - National Science Library

    George, Steven

    1997-01-01

    Our research is focusing on the atomic layer control of thin film growth. Our goal is to deposit films with precise control of thickness and conformality on both flat and high aspect ratio structures...

  5. Improved reaction kinetics and selectivity by the TiO2-embedded carbon nanofiber support for electro-oxidation of ethanol on PtRu nanoparticles

    Science.gov (United States)

    Nakagawa, Nobuyoshi; Ito, Yudai; Tsujiguchi, Takuya; Ishitobi, Hirokazu

    2014-02-01

    The electro-oxidation of ethanol by the catalyst of PtRu nanoparticles supported on a TiO2-embedded carbon nanofiber (PtRu/TECNF), which has recently been proposed by the authors as a highly active catalyst for methanol oxidation, is investigated by cyclic voltammetry using a glassy carbon electrode and by operating a direct ethanol fuel cell (DEFC) with the catalyst. The mass activity obtained from the cyclic voltammogram for the ethanol oxidation is compared to that for the methanol oxidation reported in our recent paper. The mass activity for the ethanol oxidation is comparable or slightly higher than that for the methanol oxidation, and the relationship between the TECNF composition, i.e., the Ti/C mass ratio, and the activity are also similar to that for the methanol oxidation. A DEFC fabricated with the PtRu/TECNF shows a higher power output compared to that with the commercial PtRu/C catalyst. An analysis of the reaction products by a simple two-step reaction model reveals that the PtRu/TECNF increases the rate constant for the reaction steps from ethanol to acetaldehyde and subsequently to CO2, but decreases that from acetaldehyde to acetic acid. This means that the PtRu/TECNF improves not only the kinetics, but also the selectivity to acetaldehyde.

  6. Bioconversion of D-galactose to D-tagatose: continuous packed bed reaction with an immobilized thermostable L-arabinose isomerase and efficient purification by selective microbial degradation.

    Science.gov (United States)

    Liang, Min; Chen, Min; Liu, Xinying; Zhai, Yafei; Liu, Xian-wei; Zhang, Houcheng; Xiao, Min; Wang, Peng

    2012-02-01

    The continuous enzymatic conversion of D-galactose to D-tagatose with an immobilized thermostable L-arabinose isomerase in packed-bed reactor and a novel method for D-tagatose purification were studied. L-arabinose isomerase from Thermoanaerobacter mathranii (TMAI) was recombinantly overexpressed and immobilized in calcium alginate. The effects of pH and temperature on D-tagatose production reaction catalyzed by free and immobilized TMAI were investigated. The optimal condition for free enzyme was pH 8.0, 60°C, 5 mM MnCl(2). However, that for immobilized enzyme was pH 7.5, 75°C, 5 mM MnCl(2). In addition, the catalytic activity of immobilized enzyme at high temperature and low pH was significantly improved compared with free enzyme. The optimum reaction yield with immobilized TMAI increased by four percentage points to 43.9% compared with that of free TMAI. The highest productivity of 10 g/L h was achieved with the yield of 23.3%. Continuous production was performed at 70°C; after 168 h, the reaction yield was still above 30%. The resultant syrup was then incubated with Saccharomyces cerevisiae L1 cells. The selective degradation of D-galactose was achieved, obtaining D-tagatose with the purity above 95%. The established production and separation methods further potentiate the industrial production of D-tagatose via bioconversion and biopurification processes.

  7. Temperature-controlled cross-linking of silver nanoparticles with Diels-Alder reaction and its application on antibacterial property

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lian; Yang, Pengfei, E-mail: ypf@qlu.edu.cn; Li, Junying; Zhang, Zhiliang; Yu, Xi; Lu, Ling

    2017-05-01

    Highlights: • Silver nanoparticles were functionalized by furan groups. • The DA reaction of furan with bismaleimide was used to cross-link the particles. • The reverse cross-linking could be controlled by temperature. • The antibacterial activity of silvers could be adjusted by the cross-linking. - Abstract: Sliver nanoparticles (AgNPs) were synthesized and functionalized with furan group on their surface, followed by the reverse Diels-Alder (DA) reaction with bismaleimide to vary the particle size, so as to give different antibacterial activities. These nanoparticles were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Ultraviolet-Visible (UV–vis), Nanoparticle Size Analyzer and X-Ray Photoelectron Spectroscopy (XPS). It was found that the cross-linking reaction with bismaleimide had a great effect on the size of AgNPs. The size of the AgNPs could be controlled by the temperature of DA/r-DA equilibrium. The antibacterial activity was assessed using the inhibition zone diameter by introducing the particles into a media containing Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, respectively. It was found that these particles were effective bactericides. Furthermore, the antibacterial activity of the nanoparticles decreased orderly as the particle size enlarged.

  8. Temperature-controlled cross-linking of silver nanoparticles with Diels-Alder reaction and its application on antibacterial property

    International Nuclear Information System (INIS)

    Liu, Lian; Yang, Pengfei; Li, Junying; Zhang, Zhiliang; Yu, Xi; Lu, Ling

    2017-01-01

    Highlights: • Silver nanoparticles were functionalized by furan groups. • The DA reaction of furan with bismaleimide was used to cross-link the particles. • The reverse cross-linking could be controlled by temperature. • The antibacterial activity of silvers could be adjusted by the cross-linking. - Abstract: Sliver nanoparticles (AgNPs) were synthesized and functionalized with furan group on their surface, followed by the reverse Diels-Alder (DA) reaction with bismaleimide to vary the particle size, so as to give different antibacterial activities. These nanoparticles were characterized using Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Ultraviolet-Visible (UV–vis), Nanoparticle Size Analyzer and X-Ray Photoelectron Spectroscopy (XPS). It was found that the cross-linking reaction with bismaleimide had a great effect on the size of AgNPs. The size of the AgNPs could be controlled by the temperature of DA/r-DA equilibrium. The antibacterial activity was assessed using the inhibition zone diameter by introducing the particles into a media containing Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, respectively. It was found that these particles were effective bactericides. Furthermore, the antibacterial activity of the nanoparticles decreased orderly as the particle size enlarged.

  9. Perceived control, voluntariness and emotional reactions. A study conducted in relocated areas of Russia, Ukraine and Belarus

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, C.J. [Norwegian Univ. of Science and Technology, Trondheim (Norway). Dept. of Psychology

    1999-12-01

    This paper use data from a pilot study to analyse relationships between type of resettlement (voluntary or involuntary) and individuals' everyday feelings, perceptions of risk, health status and control. The data were collected in 1995, within the Joint Study Project 2, i.e., a collaborative research project of the European Union and the Commonwealth of Independent States of Russia, Ukraine and Belarus, 1991/92 - 95/96. The aim of the study was to investigate reactions to change and new life conditions of people who had been resettled due to the Chernobyl accident. Participants from the respective countries included adult individuals sampled from two age groups of less than 45 years and 45 years and older, with approximately the same number of men and women. The questionnaire presented various topics to which responses were indicated on quantitative response scales, as well as in open ended response formats. The results presented here focus on emotional reactions, perceived risk and self-rated health among resettled people. The effects of type of resettlement on emotional reactions, Perceived risk and control are discussed.

  10. Perceived control, voluntariness and emotional reactions. A study conducted in relocated areas of Russia, Ukraine and Belarus

    International Nuclear Information System (INIS)

    Figueiredo, C.J.

    1999-01-01

    This paper use data from a pilot study to analyse relationships between type of resettlement (voluntary or involuntary) and individuals' everyday feelings, perceptions of risk, health status and control. The data were collected in 1995, within the Joint Study Project 2, i.e., a collaborative research project of the European Union and the Commonwealth of Independent States of Russia, Ukraine and Belarus, 1991/92 - 95/96. The aim of the study was to investigate reactions to change and new life conditions of people who had been resettled due to the Chernobyl accident. Participants from the respective countries included adult individuals sampled from two age groups of less than 45 years and 45 years and older, with approximately the same number of men and women. The questionnaire presented various topics to which responses were indicated on quantitative response scales, as well as in open ended response formats. The results presented here focus on emotional reactions, perceived risk and self-rated health among resettled people. The effects of type of resettlement on emotional reactions, Perceived risk and control are discussed

  11. Imaging and controlling intracellular reactions: Lysosome transport as a function of diameter and the intracellular synthesis of conducting polymers

    Science.gov (United States)

    Payne, Christine

    2014-03-01

    Eukaryotic cells are the ultimate complex environment with intracellular chemical reactions regulated by the local cellular environment. For example, reactants are sequestered into specific organelles to control local concentration and pH, motor proteins transport reactants within the cell, and intracellular vesicles undergo fusion to bring reactants together. Current research in the Payne Lab in the School of Chemistry and Biochemistry at Georgia Tech is aimed at understanding and utilizing this complex environment to control intracellular chemical reactions. This will be illustrated using two examples, intracellular transport as a function of organelle diameter and the intracellular synthesis of conducting polymers. Using single particle tracking fluorescence microscopy, we measured the intracellular transport of lysosomes, membrane-bound organelles, as a function of diameter as they underwent transport in living cells. Both ATP-dependent active transport and diffusion were examined. As expected, diffusion scales with the diameter of the lysosome. However, active transport is unaffected suggesting that motor proteins are insensitive to cytosolic drag. In a second example, we utilize intracellular complexity, specifically the distinct micro-environments of different organelles, to carry out chemical reactions. We show that catalase, found in the peroxisomes of cells, can be used to catalyze the polymerization of the conducting polymer PEDOT:PSS. More importantly, we have found that a range of iron-containing biomolecules are suitable catalysts with different iron-containing biomolecules leading to different polymer properties. These experiments illustrate the advantage of intracellular complexity for the synthesis of novel materials.

  12. Decentralized Hierarchical Controller Design for Selective Damping of Inter Area Oscillations Using PMU Signals

    Directory of Open Access Journals (Sweden)

    Ashfaque Ahmed Hashmani

    2011-07-01

    Full Text Available This paper deals with the decentralized hierarchical PSS (Power System Stabilizer controller design to achieve a better damping of specific inter-area oscillations. The two-level decentralized hierarchical structure consists of two PSS controllers. The first level controller is a local PSS controller for each generator to damp local mode in the area where controller is located. This controller uses only local signals as input signals. The local signal comes from the generator at which the controller is located. The secondary level controller is a multivariable decentralized global PSS controller to damp inter-area modes. This controller uses selected suitable wide area PMU (Phasor Measurement Units signals as inputs. The PMU or global signals are taken from network locations where the oscillations are well observable. The global controller uses only those global input signals in which the assigned single inter-area mode is most observable and is located at a generator that is most effective in controlling the assigned mode. The global controller works mainly in a frequency band given by the natural frequency of the assigned mode. The effectiveness of the resulting hierarchical controller is demonstrated through simulation studies conducted on a test power system.

  13. Objective Model Selection for Identifying the Human Feedforward Response in Manual Control.

    Science.gov (United States)

    Drop, Frank M; Pool, Daan M; van Paassen, Marinus Rene M; Mulder, Max; Bulthoff, Heinrich H

    2018-01-01

    Realistic manual control tasks typically involve predictable target signals and random disturbances. The human controller (HC) is hypothesized to use a feedforward control strategy for target-following, in addition to feedback control for disturbance-rejection. Little is known about human feedforward control, partly because common system identification methods have difficulty in identifying whether, and (if so) how, the HC applies a feedforward strategy. In this paper, an identification procedure is presented that aims at an objective model selection for identifying the human feedforward response, using linear time-invariant autoregressive with exogenous input models. A new model selection criterion is proposed to decide on the model order (number of parameters) and the presence of feedforward in addition to feedback. For a range of typical control tasks, it is shown by means of Monte Carlo computer simulations that the classical Bayesian information criterion (BIC) leads to selecting models that contain a feedforward path from data generated by a pure feedback model: "false-positive" feedforward detection. To eliminate these false-positives, the modified BIC includes an additional penalty on model complexity. The appropriate weighting is found through computer simulations with a hypothesized HC model prior to performing a tracking experiment. Experimental human-in-the-loop data will be considered in future work. With appropriate weighting, the method correctly identifies the HC dynamics in a wide range of control tasks, without false-positive results.

  14. Heterobimetallic transition metal/rare earth metal bifunctional catalysis: a Cu/Sm/Schiff base complex for syn-selective catalytic asymmetric nitro-Mannich reaction.

    Science.gov (United States)

    Handa, Shinya; Gnanadesikan, Vijay; Matsunaga, Shigeki; Shibasaki, Masakatsu

    2010-04-07

    The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)(2)/Sm(O-iPr)(3)/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)(3), we reoptimized the catalyst preparation method, and a catalyst derived from Sm(5)O(O-iPr)(13) showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)(3). The optimal system with Sm(5)O(O-iPr)(13) was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm(5)O(O-iPr)(13).

  15. Selective extraction by dissolvable (nitriloacetic acid-nickel)-layered double hydroxide coupled with reaction with potassium thiocyanate for sensitive detection of iron(III).

    Science.gov (United States)

    Tang, Sheng; Chang, Yuepeng; Shen, Wei; Lee, Hian Kee

    2016-07-01

    A highly selective method has been proposed for the determination of iron cation (Fe(3+)). (Nitriloacetic acid-nickel)-layered double hydroxide ((NTA-Ni)-LDH) was successfully synthesized and used as dissolvable sorbent in dispersive solid-phase extraction to pre-concentrate and separate Fe(3+) from aqueous phase. Since Fe(3+) has a larger formation constant with NTA compared to Ni(2+), subsequently ion exchange occurred when (NTA-Ni)-LDH was added to the sample solution. The resultant (NTA-Fe)-LDH sol was isolated and transferred in an acidic medium containing potassium thiocyanate (KSCN). Since (NTA-Fe)-LDH could be dissolved in acidic conditions, Fe(3+)was released and reacted with SCN(-) to form an Fe-SCN complex. The resulting product was measured by ultraviolet-visible spectrometry for quantitative detection of Fe(3+). Extraction factors, including sample pH, reaction pH, extraction temperature, extraction time, reaction time and concentration of KSCN were optimized. This method achieved a low limit of detection of 15.2nM and a good linear range from 0.05 to 50μM (r(2)=0.9937). A nearly 18-fold enhancement of signal intensity was achieved after selective extraction. The optimized conditions were validated by applying the method to determine Fe(3+) in seawater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Exhaustive Conversion of Inorganic Nitrogen to Nitrogen Gas Based on a Photoelectro-Chlorine Cycle Reaction and a Highly Selective Nitrogen Gas Generation Cathode.

    Science.gov (United States)

    Zhang, Yan; Li, Jinhua; Bai, Jing; Shen, Zhaoxi; Li, Linsen; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

    2018-02-06

    A novel method for the exhaustive conversion of inorganic nitrogen to nitrogen gas is proposed in this paper. The key properties of the system design included an exhaustive photoelectrochemical cycle reaction in the presence of Cl - , in which Cl· generated from oxidation of Cl - by photoholes selectively converted NH 4 + to nitrogen gas and some NO 3 - or NO 2 - . The NO 3 - or NO 2 - was finally reduced to nitrogen gas on a highly selective Pd-Cu-modified Ni foam (Pd-Cu/NF) cathode to achieve exhaustive conversion of inorganic nitrogen to nitrogen gas. The results indicated total nitrogen removal efficiencies of 30 mg L -1 inorganic nitrogen (NO 3 - , NH 4 + , NO 3 - /NH 4 + = 1:1 and NO 2 - /NO 3 - /NH 4 + = 1:1:1) in 90 min were 98.2%, 97.4%, 93.1%, and 98.4%, respectively, and the remaining nitrogen was completely removed by prolonging the reaction time. The rapid reduction of nitrate was ascribed to the capacitor characteristics of Pd-Cu/NF that promoted nitrate adsorption in the presence of an electric double layer, eliminating repulsion between the cathode and the anion. Nitrate was effectively removed with a rate constant of 0.050 min -1 , which was 33 times larger than that of Pt cathode. This system shows great potential for inorganic nitrogen treatment due to the high rate, low cost, and clean energy source.

  17. Controlling surface adsorption to enhance the selectivity of porphyrin based gas sensors

    Energy Technology Data Exchange (ETDEWEB)

    Evyapan, M., E-mail: mevyapan@gmail.com [Department of Physics, University of Balikesir, Balikesir, 10145 (Turkey); Chemical and Biological Engineering, University of Sheffield, Mappin Building, S1 3JD (United Kingdom); Dunbar, A.D.F. [Chemical and Biological Engineering, University of Sheffield, Mappin Building, S1 3JD (United Kingdom)

    2016-01-30

    Graphical abstract: The enhancement in the selectivity of the vapor sensing properties of free base porphyrin by controlling the size of the pores in the surface structure was carried out. It can be used as a size selective surface layer which limits the diffusion of analyte molecules into the sensor and in extreme cases stopping the diffusion completely. - Highlights: • Surface of a thin film takes and important part for its sensing characteristics. • A systematic surface modification was carried out in order to control the vapor accessibility. • Size dependant surfaces were fabricated. • Vapor diffusion through into thin film was controlled by modifying the surface structure. • Remarkable quantitative results showed the control on selectivity of the sensor by controlling the surface. - Abstract: This study reports an enhancement in the selectivity of the vapor sensing properties of free base porphyrin 5,10,15,20-tetrakis[3,4-bis(2-ethylhexyloxy)phenyl]-21H,23H-porphine (EHO) Langmuir–Schaefer (LS) films. These sensors respond by changing color upon adsorption of the analyte gas to the sensor surface. The enhanced selectivity is achieved by adding selective barrier layers of 4-tert-Butylcalix[4]arene, 4-tert-Butylcalix[6]arene and 4-tert-Butylcalix[8]arene embedded in PMMA (Poly(methyl methacrylate)) on top of the porphyrin sensor films to control the gaseous adsorption onto the sensor surface. The Langmuir properties of EHO, PMMA and calix[n]arene monolayers were investigated by surface pressure–area (Π–A) isotherms in order to determine the most efficient transfer pressure. Six layer EHO films were transferred onto glass and silicon substrates to investigate their optical and structural characteristics. The three different calix[n]arenes were embedded within PMMA layers to act as the selective barrier layers which were deposited on top of the six layer EHO films. The different calix[n]arene molecules vary in size and each was mixed with PMMA in

  18. Dynamic behavior of the bray-liebhafsky oscillatory reaction controlled by sulfuric acid and temperature

    Science.gov (United States)

    Pejić, N.; Vujković, M.; Maksimović, J.; Ivanović, A.; Anić, S.; Čupić, Ž.; Kolar-Anić, Lj.

    2011-12-01

    The non-periodic, periodic and chaotic regimes in the Bray-Liebhafsky (BL) oscillatory reaction observed in a continuously fed well stirred tank reactor (CSTR) under isothermal conditions at various inflow concentrations of the sulfuric acid were experimentally studied. In each series (at any fixed temperature), termination of oscillatory behavior via saddle loop infinite period bifurcation (SNIPER) as well as some kind of the Andronov-Hopf bifurcation is presented. In addition, it was found that an increase of temperature, in different series of experiments resulted in the shift of bifurcation point towards higher values of sulfuric acid concentration.

  19. Entropy-based critical reaction time for mixing-controlled reactive transport

    DEFF Research Database (Denmark)

    Chiogna, Gabriele; Rolle, Massimo

    2017-01-01

    Entropy-based metrics, such as the dilution index, have been proposed to quantify dilution and reactive mixing in solute transport problems. In this work, we derive the transient advection dispersion equation for the entropy density of a reactive plume. We restrict our analysis to the case where...... the concentration distribution of the transported species is Gaussian and we observe that, even in case of an instantaneous complete bimolecular reaction, dilution caused by dispersive processes dominates the entropy balance at early times and results in the net increase of the entropy density of a reactive species...

  20. Analytical control of an esterification batch reaction between glycerine and fatty acids by near-infrared spectroscopy

    International Nuclear Information System (INIS)

    Blanco, Marcelo; Beneyto, Rafael; Castillo, Miguel; Porcel, Marta

    2004-01-01

    Near-infrared spectroscopy was used to control an esterification reaction between glycerine and middle- or long-chain fatty acids performed in a laboratory-scale reactor. The process involves the initial formation of monoglycerides, which is followed by that of di- and triglycerides as well as transesterification. Establishing the end point of the process is critical with a view to ensuring that the end product will have the composition required for its intended use. PLS calibration was applied to industrial and laboratory-scale batch samples, and laboratory samples were additionally used to extend calibration ranges and avoid correlation between the concentration of the batch samples. In this way, PLS calibration models for glycerine, fatty acids, water, and mono-, di- and triglycerides, were constructed. The proposed method allows the reaction to be monitored in real time, thereby avoiding long analysis times, excessive reagent consumption and the obtainment of out-of-specification products