Gold-catalyzed three-component annulation: efficient synthesis of highly functionalized dihydropyrazoles from alkynes, hydrazines, and aldehydes or ketones.

PubMed

Suzuki, Yamato; Naoe, Saori; Oishi, Shinya; Fujii, Nobutaka; Ohno, Hiroaki

2012-01-06

Polysubstituted dihydropyrazoles were directly obtained by a gold-catalyzed three-component annulation. This reaction consists of a Mannich-type coupling of alkynes with N,N'-disubstituted hydrazines and aldehydes/ketones followed by intramolecular hydroamination. Cascade cyclization using 1,2-dialkynylbenzene derivatives as the alkyne component was also performed producing fused tricyclic dihydropyrazoles in good yields. © 2011 American Chemical Society

DOE Office of Scientific and Technical Information (OSTI.GOV)

Squires, Leah N.; Lessing, Paul

A process of direct reduction of neptunium oxide to neptunium metal using calcium metal as the reducing agent is discussed. After reduction of the oxide to metal, the metal is separated by density from the other components of the reaction mixture and can easily removed upon cooling. Furthermore, the direct reduction technique consistently produces high purity (98%–99% pure) neptunium metal.

Efficient Application of Continuous Fractional Component Monte Carlo in the Reaction Ensemble

PubMed Central

2017-01-01

A new formulation of the Reaction Ensemble Monte Carlo technique (RxMC) combined with the Continuous Fractional Component Monte Carlo method is presented. This method is denoted by serial Rx/CFC. The key ingredient is that fractional molecules of either reactants or reaction products are present and that chemical reactions always involve fractional molecules. Serial Rx/CFC has the following advantages compared to other approaches: (1) One directly obtains chemical potentials of all reactants and reaction products. Obtained chemical potentials can be used directly as an independent check to ensure that chemical equilibrium is achieved. (2) Independent biasing is applied to the fractional molecules of reactants and reaction products. Therefore, the efficiency of the algorithm is significantly increased, compared to the other approaches. (3) Changes in the maximum scaling parameter of intermolecular interactions can be chosen differently for reactants and reaction products. (4) The number of fractional molecules is reduced. As a proof of principle, our method is tested for Lennard-Jones systems at various pressures and for various chemical reactions. Excellent agreement was found both for average densities and equilibrium mixture compositions computed using serial Rx/CFC, RxMC/CFCMC previously introduced by Rosch and Maginn (Journal of Chemical Theory and Computation, 2011, 7, 269–279), and the conventional RxMC approach. The serial Rx/CFC approach is also tested for the reaction of ammonia synthesis at various temperatures and pressures. Excellent agreement was found between results obtained from serial Rx/CFC, experimental results from literature, and thermodynamic modeling using the Peng–Robinson equation of state. The efficiency of reaction trial moves is improved by a factor of 2 to 3 (depending on the system) compared to the RxMC/CFCMC formulation by Rosch and Maginn. PMID:28737933

Measurement of 17F(d ,n )18Ne and the impact on the 17F(p ,γ )18Ne reaction rate for astrophysics

NASA Astrophysics Data System (ADS)

Kuvin, S. A.; Belarge, J.; Baby, L. T.; Baker, J.; Wiedenhöver, I.; Höflich, P.; Volya, A.; Blackmon, J. C.; Deibel, C. M.; Gardiner, H. E.; Lai, J.; Linhardt, L. E.; Macon, K. T.; Rasco, B. C.; Quails, N.; Colbert, K.; Gay, D. L.; Keeley, N.

2017-10-01

Background: The 17F(p ,γ )18Ne reaction is part of the astrophysical "hot CNO" cycles that are important in astrophysical environments like novas. Its thermal reaction rate is low owing to the relatively high energy of the resonances and therefore is dominated by direct, nonresonant capture in stellar environments at temperatures below 0.4 GK. Purpose: An experimental method is established to extract the proton strength to bound and unbound states in experiments with radioactive ion beams and to determine the parameters of direct and resonant capture in the 17F(p ,γ )18Ne reaction. Method: The 17F(d ,n )18Ne reaction is measured in inverse kinematics using a beam of the short-lived isotope 17F and a compact setup of neutron, proton, γ -ray, and heavy-ion detectors called resoneut. Results: The spectroscopic factors for the lowest l =0 proton resonances at Ec .m .=0.60 and 1.17 MeV are determined, yielding results consistent within 1.4 σ of previous proton elastic-scattering measurements. The asymptotic normalization coefficients of the bound 21+ and 22+ states in 18Ne are determined and the resulting direct-capture reaction rates are extracted. Conclusions: The direct-capture component of the 17F(p ,γ )18Ne reaction is determined for the first time from experimental data on 18Ne.

α-Unsubstituted Pyrroles by NHC-Catalyzed Three-Component Coupling: Direct Synthesis of a Versatile Atorvastatin Derivative.

PubMed

Fleige, Mirco; Glorius, Frank

2017-08-10

A practical one-pot cascade reaction protocol provides direct access to valuable 1,2,4-trisubstituted pyrroles. The process involves an N-heterocyclic carbene (NHC)-catalyzed Stetter-type hydroformylation using glycolaldehyde dimer as a novel C1 building-block, followed by a Paal-Knorr condensation with primary amines. The reaction makes use of simple and commercially available starting-materials and catalyst, an important feature regarding applicability and utility. Low catalyst loading under mild reaction conditions afforded a variety of 1,2,4-substituted pyrroles in a transition-metal-free reaction with high step economy and good yields. This methodology is applied in the synthesis of a versatile Atorvastatin precursor, in which a variety of modifications at the pyrrole core structure are possible. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave-assisted domino and multicomponent reactions with cyclic acylketenes: expeditious syntheses of oxazinones and oxazindiones.

PubMed

Presset, Marc; Coquerel, Yoann; Rodriguez, Jean

2009-12-17

The microwave-assisted Wolff rearrangement of cyclic 2-diazo-1,3-diketones in the presence of aldehydes and primary amines provides a straightforward access to functionalized bi- and pentacyclic oxazinones following an unprecedented three-component domino reaction. Alternatively, in the presence of acyl azides, an efficient Curtius/Wolff/hetero-Diels-Alder sequence allows the direct synthesis of oxazindiones.

Active control of complex, multicomponent self-assembly processes

NASA Astrophysics Data System (ADS)

Schulman, Rebecca

The kinetics of many complex biological self-assembly processes such as cytoskeletal assembly are precisely controlled by cells. Spatiotemporal control over rates of filament nucleation, growth and disassembly determine how self-assembly occurs and how the assembled form changes over time. These reaction rates can be manipulated by changing the concentrations of the components needed for assembly by activating or deactivating them. I will describe how we can use these principles to design driven self-assembly processes in which we assemble and disassemble multiple types of components to create micron-scale networks of semiflexible filaments assembled from DNA. The same set of primitive components can be assembled into many different, structures depending on the concentrations of different components and how designed, DNA-based chemical reaction networks manipulate these concentrations over time. These chemical reaction networks can in turn interpret environmental stimuli to direct complex, multistage response. Such a system is a laboratory for understanding complex active material behaviors, such as metamorphosis, self-healing or adaptation to the environment that are ubiquitous in biological systems but difficult to quantitatively characterize or engineer.

Direct chemical reduction of neptunium oxide to neptunium metal using calcium and calcium chloride

DOE PAGES

Squires, Leah N.; Lessing, Paul

2016-01-13

A process of direct reduction of neptunium oxide to neptunium metal using calcium metal as the reducing agent is discussed. After reduction of the oxide to metal, the metal is separated by density from the other components of the reaction mixture and can easily removed upon cooling. Furthermore, the direct reduction technique consistently produces high purity (98%–99% pure) neptunium metal.

Individual differences in the impact of vicarious racism: African American students react to the George Zimmerman trial.

PubMed

Mason, Tyler B; Maduro, Ralitsa S; Derlega, Valerian J; Hacker, Desi S; Winstead, Barbara A; Haywood, Jacqueline E

2017-04-01

This research focused on how race-based rejection sensitivity (RS-Race) and components of racial identity intensify negative psychological reactions to an incident of vicarious racism. We examined how these individual difference variables directly and/or indirectly predicted African American students' reactions to the trial of George Zimmerman in the killing of the African American teenager, Trayvon Martin. In Study 1, 471 African American students completed measures of RS-Race, thought intrusions about the Zimmerman trial, and outcome variables (negative affect about the Zimmerman trial and forgiveness for Mr. Zimmerman). In Study 2, 304 African American students completed measures of racial identity (centrality, private regard, and public regard), thought intrusions about the Zimmerman trial, negative affect, and forgiveness. In Study 1, higher RS-Race was either directly and/or indirectly (via thought intrusions) related to more negative affect and lower forgiveness. In Study 2, high racial centrality and low public regard either directly and/or indirectly (via thought intrusions) predicted more negative affect and lower forgiveness. RS-Race and specific components of racial identity are likely to sensitize African Americans to incidents of racism that happen to other African Americans, leading to negative psychological reactions when these events occur. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Dissociating motivational direction and affective valence: specific emotions alter central motor processes.

PubMed

Coombes, Stephen A; Cauraugh, James H; Janelle, Christopher M

2007-11-01

We aimed to clarify the relation between affective valence and motivational direction by specifying how central and peripheral components of extension movements are altered according to specific unpleasant affective states. As predicted, premotor reaction time was quicker for extension movements initiated during exposure to attack than for extension movements initiated during exposure to all other valence categories (mutilation, erotic couples, opposite-sex nudes, neutral humans, household objects, blank). Exposure to erotic couples and mutilations yielded greater peak force than exposure to images of attack, neutral humans, and household objects. Finally, motor reaction time and peak electromyographic amplitude were not altered by valence. These findings indicate that unpleasant states do not unilaterally prime withdrawal movements, and that the quick execution of extension movements during exposure to threatening images is due to rapid premotor, rather than motor, reaction time. Collectively, our findings support the call for dissociating motivational direction and affective valence.

Synthesis of a new class of Betti bases by the Mannich-type reaction: efficient, facile, solvent-free and one-pot protocol.

PubMed

Shahrisa, Aziz; Teimuri-Mofrad, Reza; Gholamhosseini-Nazari, Mahdi

2015-02-01

A variety of organocatalysts has been screened for the synthesis of arylaminonaphthols. It has been shown that (N,N-dimethylethanolamine) is a highly efficient organocatalyst for the direct synthesis of a novel class of arylaminonaphthols via three-component condensation of 2-naphthol, aldehydes, and arylamines under solvent-free conditions. Mild, one-pot, and green reaction conditions, relatively short reaction times and good yields make this protocol highly significant. 25 new compounds have been synthesized by this method.

Titanium isopropoxide as efficient catalyst for the aza-Baylis-Hillman reaction. Selective formation of alpha-methylene-beta-amino acid derivatives.

PubMed

Balan, Daniela; Adolfsson, Hans

2002-04-05

The direct formation of alpha-methylene-beta-amino acid derivatives is achieved using the aza version of the Baylis-Hillman protocol. The products are readily formed in a three-component one-pot reaction between arylaldehydes, sulfonamides, and alpha,beta-unsaturated carbonyl compounds. The reaction is efficiently catalyzed by titanium isopropoxide and 2-hydroxyquinuclidine in the presence of molecular sieves. The protocol allows for structural variation of the substrates, tolerating electron-poor and electron-rich arylaldehydes and various Michael acceptors.

Self-Consistency of the Theory of Elementary Stage Rates of Reversible Processes and the Equilibrium Distribution of Reaction Mixture Components

NASA Astrophysics Data System (ADS)

Tovbin, Yu. K.

2018-06-01

An analysis is presented of one of the key concepts of physical chemistry of condensed phases: the theory self-consistency in describing the rates of elementary stages of reversible processes and the equilibrium distribution of components in a reaction mixture. It posits that by equating the rates of forward and backward reactions, we must obtain the same equation for the equilibrium distribution of reaction mixture components, which follows directly from deducing the equation in equilibrium theory. Ideal reaction systems always have this property, since the theory is of a one-particle character. Problems arise in considering interparticle interactions responsible for the nonideal behavior of real systems. The Eyring and Temkin approaches to describing nonideal reaction systems are compared. Conditions for the self-consistency of the theory for mono- and bimolecular processes in different types of interparticle potentials, the degree of deviation from the equilibrium state, allowing for the internal motions of molecules in condensed phases, and the electronic polarization of the reagent environment are considered within the lattice gas model. The inapplicability of the concept of an activated complex coefficient for reaching self-consistency is demonstrated. It is also shown that one-particle approximations for considering intermolecular interactions do not provide a theory of self-consistency for condensed phases. We must at a minimum consider short-range order correlations.

Epithermal neutron beams from the 7 Li(p,n) reaction near the threshold for neutron capture therapy

NASA Astrophysics Data System (ADS)

Porras, I.; Praena, J.; Arias de Saavedra, F.; Pedrosa, M.; Esquinas, P.; L. Jiménez-Bonilla, P.

2016-11-01

Two applications for neutron capture therapy of epithermal neutron beams calculated from the 7Li ( p , n reaction are discussed. In particular, i) for a proton beam of 1920 keV of a 30 mA, a neutron beam of adequate features for BNCT is found at an angle of 80° from the forward direction; and ii) for a proton beam of 1910 keV, a neutron beam is obtained at the forward direction suitable for performing radiobiology experiments for the determination of the biological weighting factors of the fast dose component in neutron capture therapy.

Protein-solvent preferential interactions, protein hydration, and the modulation of biochemical reactions by solvent components.

PubMed

Timasheff, Serge N

2002-07-23

Solvent additives (cosolvents, osmolytes) modulate biochemical reactions if, during the course of the reaction, there is a change in preferential interactions of solvent components with the reacting system. Preferential interactions can be expressed in terms of preferential binding of the cosolvent or its preferential exclusion (preferential hydration). The driving force is the perturbation by the protein of the chemical potential of the cosolvent. It is shown that the measured change of the amount of water in contact with protein during the course of the reaction modulated by an osmolyte is a change in preferential hydration that is strictly a measure of the cosolvent chemical potential perturbation by the protein in the ternary water-protein-cosolvent system. It is not equal to the change in water of hydration, because water of hydration is a reflection strictly of protein-water forces in a binary system. There is no direct relation between water of preferential hydration and water of hydration.

Method and apparatus for purifying nucleic acids and performing polymerase chain reaction assays using an immiscible fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koh, Chung-Yan; Light, Yooli Kim; Piccini, Matthew Ernest

Embodiments of the present invention are directed toward devices, systems, and methods for purifying nucleic acids to conduct polymerase chain reaction (PCR) assays. In one example, a method includes generating complexes of silica beads and nucleic acids in a lysis buffer, transporting the complexes through an immiscible fluid to remove interfering compounds from the complexes, further transporting the complexes into a density medium containing components required for PCR where the nucleic acids disassociate from the silica beads, and thermocycling the contents of the density medium to achieve PCR. Signal may be detected from labeling agents in the components required formore » PCR.« less

High temperature lubricating process

DOEpatents

Taylor, R.W.; Shell, T.E.

1979-10-04

It has been difficult to provide adequate lubrication for load bearing, engine components when such engines are operating in excess of about 475/sup 0/C. The present invention is a process for providing a solid lubricant on a load bearing, solid surface, such as in an engine being operated at temperatures in excess of about 475/sup 0/C. The process comprises contacting and maintaining the following steps: a gas phase is provided which includes at least one component reactable in a temperature dependent reaction to form a solid lubricant; the gas phase is contacted with the load bearing surface; the load bearing surface is maintained at a temperature which causes reaction of the gas phase component and the formation of the solid lubricant; and the solid lubricant is formed directly on the load bearing surface. The method is particularly suitable for use with ceramic engines.

High temperature lubricating process

DOEpatents

Taylor, Robert W.; Shell, Thomas E.

1982-01-01

It has been difficult to provide adaquate lubrication for load bearing, engine components when such engines are operating in excess of about 475.degree. C. The present invention is a process for providing a solid lubricant on a load bearing, solid surface (14), such as in an engine (10) being operated at temperatures in excess of about 475.degree. C. The process comprises contacting and maintaining steps. A gas phase (42) is provided which includes at least one component reactable in a temperature dependent reaction to form a solid lubricant. The gas phase is contacted with the load bearing surface. The load bearing surface is maintained at a temperature which causes reaction of the gas phase component and the formation of the solid lubricant. The solid lubricant is formed directly on the load bearing surface. The method is particularly suitable for use with ceramic engines.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts.

PubMed

Li, Chunjie; Wang, Hongjing; Li, Yinghao; Yu, Hongjie; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-06-22

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts

NASA Astrophysics Data System (ADS)

Li, Chunjie; Wang, Hongjing; Li, Yinghao; Yu, Hongjie; Yin, Shuli; Xue, Hairong; Li, Xiaonian; Xu, You; Wang, Liang

2018-06-01

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Chemical dynamics simulations of the monohydrated OH-(H2O) + CH3I reaction. Atomic-level mechanisms and comparison with experiment

NASA Astrophysics Data System (ADS)

Xie, Jing; Otto, Rico; Wester, Roland; Hase, William L.

2015-06-01

Direct dynamics simulations, with B97-1/ECP/d theory, were performed to study the role of microsolvation for the OH-(H2O) + CH3I reaction. The SN2 reaction dominates at all reactant collision energies, but at higher collision energies proton transfer to form CH2I-, and to a lesser extent CH2I- (H2O), becomes important. The SN2 reaction occurs by direct rebound and stripping mechanisms, and 28 different indirect atomistic mechanisms, with the latter dominating. Important components of the indirect mechanisms are the roundabout and formation of SN2 and proton transfer pre-reaction complexes and intermediates, including [CH3--I--OH]-. In contrast, for the unsolvated OH- + CH3I SN2 reaction, there are only seven indirect atomistic mechanisms and the direct mechanisms dominate. Overall, the simulation results for the OH-(H2O) + CH3IߙSN2 reaction are in good agreement with experiment with respect to reaction rate constant, product branching ratio, etc. Differences between simulation and experiment are present for the SN2 velocity scattering angle at high collision energies and the proton transfer probability at low collision energies. Equilibrium solvation by the H2O molecule is unimportant. The SN2 reaction is dominated by events in which H2O leaves the reactive system as CH3OH is formed or before CH3OH formation. Formation of solvated products is unimportant and participation of the (H2O)CH3OH---I- post-reaction complex for the SN2 reaction is negligible.

Direct observation of forward-scattering oscillations in the H+HD→H2+D reaction

NASA Astrophysics Data System (ADS)

Yuan, Daofu; Yu, Shengrui; Chen, Wentao; Sang, Jiwei; Luo, Chang; Wang, Tao; Xu, Xin; Casavecchia, Piergiorgio; Wang, Xingan; Sun, Zhigang; Zhang, Dong H.; Yang, Xueming

2018-06-01

Accurate measurements of product state-resolved angular distributions are central to fundamental studies of chemical reaction dynamics. Yet, fine quantum-mechanical structures in product angular distributions of a reactive scattering process, such as the fast oscillations in the forward-scattering direction, have never been observed experimentally and the nature of these oscillations has not been fully explored. Here we report the crossed-molecular-beam experimental observation of these fast forward-scattering oscillations in the product angular distribution of the benchmark chemical reaction, H + HD → H2 + D. Clear oscillatory structures are observed for the H2(v' = 0, j' = 1, 3) product states at a collision energy of 1.35 eV, in excellent agreement with the quantum-mechanical dynamics calculations. Our analysis reveals that the oscillatory forward-scattering components are mainly contributed by the total angular momentum J around 28. The partial waves and impact parameters responsible for the forward scatterings are also determined from these observed oscillations, providing crucial dynamics information on the transient reaction process.

Catalytic total hydrodeoxygenation of biomass-derived polyfunctionalized substrates to alkanes.

PubMed

Nakagawa, Yoshinao; Liu, Sibao; Tamura, Masazumi; Tomishige, Keiichi

2015-04-13

The total hydrodeoxygenation of carbohydrate-derived molecules to alkanes, a key reaction in the production of biofuel, was reviewed from the aspect of catalysis. Noble metals (or Ni) and acid are the main components of the catalysts, and group 6 or 7 metals such as Re are sometimes added as modifiers of the noble metal. The main reaction route is acid-catalyzed dehydration plus metal-catalyzed hydrogenation, and in some systems metal-catalyzed direct CO dissociation is involved. The appropriate active metal, acid strength, and reaction conditions depend strongly on the reactivity of the substrate. Reactions that use Pt or Pd catalysts supported on Nb-based acids or relatively weak acids are suitable for furanic substrates. Carbohydrates themselves and sugar alcohols undergo CC dissociation easily. The systems that use metal-catalyzed direct CO dissociations can give a higher yield of the corresponding alkane from carbohydrates and sugar alcohols. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Apollo experience report: Detection and minimization of ignition hazards from water/glycol contamination of silver-clad electrical circuitry

NASA Technical Reports Server (NTRS)

Downs, W. R.

1976-01-01

The potential flammability hazard when a water/glycol solution contacts defectively insulated silver-clad copper circuitry or electrical components carrying a direct current is described. The chemical reactions and means for detecting them are explained. Methods for detecting and cleaning contaminated areas and the use of inhibitors to arrest chemical reactivity are also explained. Preventive measures to minimize hazards are given. Photomicrographs of the chemical reactions occurring on silver clad wires are also included.

Biocompatibility tests of components of an implantable cardiac assist device.

PubMed

von Recum, A F; Imamura, H; Freed, P S; Kantrowitz, A; Chen, S T; Ekstrom, M E; Baechler, C A; Barnhart, M I

1978-09-01

A permanently implantable in-series left ventricular assist device, the dynamic aortic patch (DAP), has been tested in chronic animal experiments. The DAP replaces a section of the intrathoracic aortic wall. Hemothorax and hematocele at the implantation site have been complications in recent experiments. Primary postoperative hemorrhage was ruled out, and the biocompatibility of all components was therefore examined. Dacron velour, Teflon felt, conductive polyurethane, segmented polyether polyurethane, and Teflon-coated polyester fiber sutures were implanted in the pleural cavities of dogs and tested in vitro by culturing canine saphenous vein explants on them. In vivo experiments demonstrated that all components elicited mild to moderate inflammatory reactions, but hematocele occurred only when the components were implanted in the aorta with direct blood contact and exposed to arterial blood pressures. In vitro, cells were cultured on all components with no signs of toxic reactions. These results indicated that the host tolerated all implant components without major inflammatory responses. However, histological data indicated that chronic slow bleeding into or through the Dacron velour in contact with the arterial blood serum could account for hemothorax or hematocele formation. Therefore, a configuration of the assist device using materials impermeable to blood may obviate these difficulties.

Analysis of transformations of the ultrafast electron transfer photoreaction mechanism in liquid solutions by the rate distribution approach.

PubMed

Kuzmin, Michael G; Soboleva, Irina V

2014-05-01

Representation of the experimental reaction kinetics in the form of rate distribution is shown to be an effective method for the analysis of the mechanisms of these reactions and for comparisons of the kinetics with QC calculations, as well as with the experimental data on the medium mobility. The rate constant distribution function P(k) can be obtained directly from the experimental kinetics N(t) by an inverse Laplace transform. The application of this approach to kinetic data for several excited-state electron transfer reactions reveals the transformations of their rate control factors in the time domain of 1-1000 ps. In neat electron donating solvents two components are observed. The fastest component (k > 1 ps(-1)) was found to be controlled by the fluctuations of the overall electronic coupling matrix element, involving all the reactant molecules, located inside the interior of the solvent shell, rather than for specific pairs of reactant molecules. The slower component (1 > k > 0.1 ps(-1)) is controlled by the medium reorganization (longitudinal relaxation times, τL). A substantial contribution from the non-stationary diffusion controlled reaction is observed in diluted solutions ([Q] < 1 M). No contribution from the long-distance electron transfer (electron tunneling) proposed earlier for the excited-state electron transfer between perylene and tetracyanoethylene in acetonitrile is observed. The rate distribution approach provides a simple and efficient method for the quantitative analysis of the reaction mechanism and transformation of the rate control factors in the course of the reactions.

Simulation studies of the Cl- + CH3I SN2 nucleophilic substitution reaction: Comparison with ion imaging experiments

NASA Astrophysics Data System (ADS)

Zhang, Jiaxu; Lourderaj, Upakarasamy; Sun, Rui; Mikosch, Jochen; Wester, Roland; Hase, William L.

2013-03-01

In the previous work of Mikosch et al. [Science 319, 183 (2008)], 10.1126/science.1150238, ion imaging experiments were used to study the Cl- + CH3I → ClCH3 + I- reaction at collision energies Erel of 0.39, 0.76, 1.07, and 1.9 eV. For the work reported here MP2(fc)/ECP/d direct dynamics simulations were performed to obtain an atomistic understanding of the experiments. There is good agreement with the experimental product energy and scattering angle distributions for the highest three Erel, and at these energies 80% or more of the reaction is direct, primarily occurring by a rebound mechanism with backward scattering. At 0.76 eV there is a small indirect component, with isotropic scattering, involving formation of the pre- and post-reaction complexes. All of the reaction is direct at 1.07 eV. Increasing Erel to 1.9 eV opens up a new indirect pathway, the roundabout mechanism. The product energy is primarily partitioned into relative translation for the direct reactions, but to CH3Cl internal energy for the indirect reactions. The roundabout mechanism transfers substantial energy to CH3Cl rotation. At Erel = 0.39 eV both the experimental product energy partitioning and scattering are statistical, suggesting the reaction is primarily indirect with formation of the pre- and post-reaction complexes. However, neither MP2 nor BhandH/ECP/d simulations agree with experiment and, instead, give reaction dominated by direct processes as found for the higher collision energies. Decreasing the simulation Erel to 0.20 eV results in product energy partitioning and scattering which agree with the 0.39 eV experiment. The sharp transition from a dominant direct to indirect reaction as Erel is lowered from 0.39 to 0.20 eV is striking. The lack of agreement between the simulations and experiment for Erel = 0.39 eV may result from a distribution of collision energies in the experiment and/or a shortcoming in both the MP2 and BhandH simulations. Increasing the reactant rotational temperature from 75 to 300 K for the 1.9 eV collisions, results in more rotational energy in the CH3Cl product and a larger fraction of roundabout trajectories. Even though a ClCH3-I- post-reaction complex is not formed and the mechanistic dynamics are not statistical, the roundabout mechanism gives product energy partitioning in approximate agreement with phase space theory.

Strong refraction near the Venus surface - Effects observed by descent probes

NASA Technical Reports Server (NTRS)

Croft, T. A.

1982-01-01

The telemetry signals from Pioneer Venus probes indicated the strong downward refraction of radio waves. As the probes descended, the strength of the direct signal decreased because of absorption and refractive defocusing. During the last 30 km of descent there was a second measured component in addition to the direct signal. Strong atmospheric reaction is important in strengthening echoes that are scattered toward the earth. Such surface-reflected signals are good indicators of horizontal winds.

An EMG study on characteristics of premotor and motor components in an agility reaction time test on athletes.

PubMed

Zhang, J; Chen, R; Wu, Y; Li, K; Wang, D; Liu, Y; Li, Y

2013-10-01

How do athletes control their foot movement so they can react fast in sports? Which component of the process may be more sensitive to training? These questions related to athletes' agility performance have long been important to the field of sport sciences, but are still unclear. The present study used surface electromyography (EMG) on the tibialis anterior (TA) and gastrocnemius medial (GM) of both left and right to assess if there would be any different contributions between premotor time (PRT) and motor time (MT) to the overall reaction time (RT). Fifty-five right-footed male college athletes (M=20.62 years old; SD=1.01) were required to respond to a random visual stimulus using foot movement as fast as possible in four different directions (i.e., forward and backward in their left or right foot). High correlation coefficients between PMT and RT in all four directions (ranging from 0.866 to 0.909) were revealed, but not between MT and RT (ranging from 0.131 to 0.336). Lateral and sagittal axes significantly interacted based on RT. The left forward direction was slowest among all directions. The process of decision making, not the preparation of execution, plays a significant role in fast and accurate reactive responses; the slowest RT in the forward direction of the left foot may be related to response programming. The corresponding training should be emphasized in order to improve athletes' agility performance.

Conditional iron and pH-dependent activity of a non-enzymatic glycolysis and pentose phosphate pathway.

PubMed

Keller, Markus A; Zylstra, Andre; Castro, Cecilia; Turchyn, Alexandra V; Griffin, Julian L; Ralser, Markus

2016-01-01

Little is known about the evolutionary origins of metabolism. However, key biochemical reactions of glycolysis and the pentose phosphate pathway (PPP), ancient metabolic pathways central to the metabolic network, have non-enzymatic pendants that occur in a prebiotically plausible reaction milieu reconstituted to contain Archean sediment metal components. These non-enzymatic reactions could have given rise to the origin of glycolysis and the PPP during early evolution. Using nuclear magnetic resonance spectroscopy and high-content metabolomics that allowed us to measure several thousand reaction mixtures, we experimentally address the chemical logic of a metabolism-like network constituted from these non-enzymatic reactions. Fe(II), the dominant transition metal component of Archean oceanic sediments, has binding affinity toward metabolic sugar phosphates and drives metabolism-like reactivity acting as both catalyst and cosubstrate. Iron and pH dependencies determine a metabolism-like network topology and comediate reaction rates over several orders of magnitude so that the network adopts conditional activity. Alkaline pH triggered the activity of the non-enzymatic PPP pendant, whereas gentle acidic or neutral conditions favored non-enzymatic glycolytic reactions. Fe(II)-sensitive glycolytic and PPP-like reactions thus form a chemical network mimicking structural features of extant carbon metabolism, including topology, pH dependency, and conditional reactivity. Chemical networks that obtain structure and catalysis on the basis of transition metals found in Archean sediments are hence plausible direct precursors of cellular metabolic networks.

Conditional iron and pH-dependent activity of a non-enzymatic glycolysis and pentose phosphate pathway

PubMed Central

Keller, Markus A.; Zylstra, Andre; Castro, Cecilia; Turchyn, Alexandra V.; Griffin, Julian L.; Ralser, Markus

2016-01-01

Little is known about the evolutionary origins of metabolism. However, key biochemical reactions of glycolysis and the pentose phosphate pathway (PPP), ancient metabolic pathways central to the metabolic network, have non-enzymatic pendants that occur in a prebiotically plausible reaction milieu reconstituted to contain Archean sediment metal components. These non-enzymatic reactions could have given rise to the origin of glycolysis and the PPP during early evolution. Using nuclear magnetic resonance spectroscopy and high-content metabolomics that allowed us to measure several thousand reaction mixtures, we experimentally address the chemical logic of a metabolism-like network constituted from these non-enzymatic reactions. Fe(II), the dominant transition metal component of Archean oceanic sediments, has binding affinity toward metabolic sugar phosphates and drives metabolism-like reactivity acting as both catalyst and cosubstrate. Iron and pH dependencies determine a metabolism-like network topology and comediate reaction rates over several orders of magnitude so that the network adopts conditional activity. Alkaline pH triggered the activity of the non-enzymatic PPP pendant, whereas gentle acidic or neutral conditions favored non-enzymatic glycolytic reactions. Fe(II)-sensitive glycolytic and PPP-like reactions thus form a chemical network mimicking structural features of extant carbon metabolism, including topology, pH dependency, and conditional reactivity. Chemical networks that obtain structure and catalysis on the basis of transition metals found in Archean sediments are hence plausible direct precursors of cellular metabolic networks. PMID:26824074

Direct observation of forward-scattering oscillations in the H+HD→H2+D reaction.

PubMed

Yuan, Daofu; Yu, Shengrui; Chen, Wentao; Sang, Jiwei; Luo, Chang; Wang, Tao; Xu, Xin; Casavecchia, Piergiorgio; Wang, Xingan; Sun, Zhigang; Zhang, Dong H; Yang, Xueming

2018-06-01

Accurate measurements of product state-resolved angular distributions are central to fundamental studies of chemical reaction dynamics. Yet, fine quantum-mechanical structures in product angular distributions of a reactive scattering process, such as the fast oscillations in the forward-scattering direction, have never been observed experimentally and the nature of these oscillations has not been fully explored. Here we report the crossed-molecular-beam experimental observation of these fast forward-scattering oscillations in the product angular distribution of the benchmark chemical reaction, H + HD → H 2  + D. Clear oscillatory structures are observed for the H 2 (v' = 0, j' = 1, 3) product states at a collision energy of 1.35 eV, in excellent agreement with the quantum-mechanical dynamics calculations. Our analysis reveals that the oscillatory forward-scattering components are mainly contributed by the total angular momentum J around 28. The partial waves and impact parameters responsible for the forward scatterings are also determined from these observed oscillations, providing crucial dynamics information on the transient reaction process.

Chemical dynamics simulations of the monohydrated OH{sup −}(H{sub 2}O) + CH{sub 3}I reaction. Atomic-level mechanisms and comparison with experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Jing; Hase, William L., E-mail: bill.hase@ttu.edu; Otto, Rico

2015-06-28

Direct dynamics simulations, with B97-1/ECP/d theory, were performed to study the role of microsolvation for the OH{sup −}(H{sub 2}O) + CH{sub 3}I reaction. The S{sub N}2 reaction dominates at all reactant collision energies, but at higher collision energies proton transfer to form CH{sub 2}I{sup −}, and to a lesser extent CH{sub 2}I{sup −} (H{sub 2}O), becomes important. The S{sub N}2 reaction occurs by direct rebound and stripping mechanisms, and 28 different indirect atomistic mechanisms, with the latter dominating. Important components of the indirect mechanisms are the roundabout and formation of S{sub N}2 and proton transfer pre-reaction complexes and intermediates, includingmore » [CH{sub 3}--I--OH]{sup −}. In contrast, for the unsolvated OH{sup −} + CH{sub 3}I S{sub N}2 reaction, there are only seven indirect atomistic mechanisms and the direct mechanisms dominate. Overall, the simulation results for the OH{sup −}(H{sub 2}O) + CH{sub 3}I S{sub N}2 reaction are in good agreement with experiment with respect to reaction rate constant, product branching ratio, etc. Differences between simulation and experiment are present for the S{sub N}2 velocity scattering angle at high collision energies and the proton transfer probability at low collision energies. Equilibrium solvation by the H{sub 2}O molecule is unimportant. The S{sub N}2 reaction is dominated by events in which H{sub 2}O leaves the reactive system as CH{sub 3}OH is formed or before CH{sub 3}OH formation. Formation of solvated products is unimportant and participation of the (H{sub 2}O)CH{sub 3}OH---I{sup −} post-reaction complex for the S{sub N}2 reaction is negligible.« less

Supramolecular catalysis beyond enzyme mimics.

PubMed

Meeuwissen, Jurjen; Reek, Joost N H

2010-08-01

Supramolecular catalysis - the assembly of catalyst species by harnessing multiple weak intramolecular interactions - has, until recently, been dominated by enzyme-inspired approaches. Such approaches often attempt to create an enzyme-like 'active site' and have concentrated on reactions similar to those catalysed by enzymes themselves. Here, we discuss the application of supramolecular assembly to the more traditional transition metal catalysis and to small-molecule organocatalysis. The modularity of self-assembled multicomponent catalysts means that a relatively small pool of catalyst components can provide rapid access to a large number of catalysts that can be evaluated for industrially relevant reactions. In addition, we discuss how catalyst-substrate interactions can be tailored to direct substrates along particular reaction paths and selectivities.

The Scales Of Chemical Transport During Dehydration Reactions: The Roles Of Diffusion And Fluid Expulsion

NASA Astrophysics Data System (ADS)

Bedford, J. D.; Wheeler, J.; Fusseis, F.; Leclere, H.; Faulkner, D.

2016-12-01

The growth of new minerals in response to disequilibrium is the most fundamental metamorphic process. However, the kinetics controls on metamorphic reactions, including the transport of chemical components to growing minerals, are poorly understood as direct observation has been impossible both in nature and experiments. Dehydration reactions are common during prograde metamorphism and require both the expulsion of H2O and the transport of solid chemical components to the product mineral(s) in order for reaction to proceed. The expulsion of H2O is particularly important in understanding when fluid overpressures might develop, which can in turn lead to sudden failure (earthquakes) if the fluid is unable to drain. Using time-resolved (4D) synchrotron X-ray microtomography we have imaged a complete dehydration reaction and show how chemical transport of both the solid and fluid phases evolves during reaction. The reaction analysed is the dehydration of gypsum to form bassanite and H2O - an analogue for silicate dehydration but with much faster and controllable reaction rate. Like most dehydration reactions, the breakdown of gypsum is associated with a solid volume reduction which generates pore space. This new porosity wraps around growing bassanite grains, producing fluid-filled moats, across which transport of dissolved solutes to the growing grains occurs via diffusion. As moats grow in width, diffusion and hence reaction rate slow down. Each new grain-moat pair evolves in relative isolation from each other indicating that the chemical transport of solid components occurs over relatively short distances. This is despite the overall pore network becoming connected during the early stages of reaction, thus allowing efficient expulsion of excess H2O. A dehydrating system can therefore act as an open system with respect to the fluid phase and in contrast be restricted to the grain-scale with respect to the dissolved chemicals. This is in accord with observations that many rocks appear to have preserved their chemistry during dehydration (apart from the loss of H2O).

Copper-catalyzed trifluoromethylthiolation of aryl halides with diverse directing groups.

PubMed

Xu, Jiabin; Mu, Xin; Chen, Pinhong; Ye, Jinxing; Liu, Guosheng

2014-08-01

The expansion of cross-coupling components in Cu-catalyzed C-X bond forming reactions have received much attention recently. A novel Cu-catalyzed trifluoromethylthiolation of aryl bromides and iodides with the assistance of versatile directing groups such as pyridyl, methyl ester, amide, imine and oxime was reported. CuBr was used as the catalyst, and 1,10-phenanthroline as the ligand. By changing the solvent from acetonitrile to DMF, the coupling process could even take place at room temperature.

Reactions in 1,1,1-trifluoroacetone triggered by low energy electrons (0-10 eV): from simple bond cleavages to complex unimolecular reactions.

PubMed

Illenberger, Eugen; Meinke, Martina C

2014-08-21

The impact of low energy electrons (0-10 eV) to 1,1,1-trifluoroacetone yields a variety of fragment anions which are formed via dissociative electron attachment (DEA) through three pronounced resonances located at 0.8 eV, near 4 eV, and in the energy range 8-9 eV. The fragment ions arise from different reactions ranging from the direct cleavage of one single or double bond (formation of F(-), CF3(-), O(-), (M-H)(-), and M-F)(-)) to remarkably complex unimolecular reactions associated with substantial geometric and electronic rearrangement in the transitory intermediate (formation of OH(-), FHF(-), (M-HF)(-), CCH(-), and HCCO(-). The ion CCH(-), for example, is formed by an excision of unit from the target molecule through the concerted cleavage of four bonds and recombination to H2O within the neutral component of the reaction.

Calculation of astrophysical S-factor in reaction ^{13}C(p,γ )^{14}N for first resonance levels

NASA Astrophysics Data System (ADS)

Moghadasi, A.; Sadeghi, H.; Pourimani, R.

2018-01-01

The ^{13}C(p,γ )^{14}N reaction is one of the important reactions in the CNO cycle, which is a key process in nucleosynthesis. We first calculated wave functions for the bound state of ^{14}N with Faddeev's method. In this method, the considered reaction components are ^{12}C+n+p. Then, by using direct capture cross section and Breit-Wigner formulae, the non-resonant and resonant cross sections were calculated, respectively. In the next step, we calculated the total S-factor and compared it with experimental data, which showed good agreement between them. Next, we extrapolated the S-factor for the transition to the ground state at zero energy and obtained S(0)=5.8 ± 0.7 (keV b) and then calculate reaction rate. These ones are in agreement with previous reported results.

Normobaric hypoxia overnight impairs cognitive reaction time.

PubMed

Pramsohler, Stephan; Wimmer, Stefan; Kopp, Martin; Gatterer, Hannes; Faulhaber, Martin; Burtscher, Martin; Netzer, Nikolaus Cristoph

2017-05-15

Impaired reaction time in patients suffering from hypoxia during sleep, caused by sleep breathing disorders, is a well-described phenomenon. High altitude sleep is known to induce periodic breathing with central apneas and oxygen desaturations, even in perfectly healthy subjects. However, deficits in reaction time in mountaineers or workers after just some nights of hypoxia exposure are not sufficiently explored. Therefore, we aimed to investigate the impact of sleep in a normobaric hypoxic environment on reaction time divided by its cognitive and motoric components. Eleven healthy non acclimatized students (5f, 6m, 21 ± 2.1 years) slept one night at a simulated altitude of 3500 m in a normobaric hypoxic room, followed by a night with polysomnography at simulated 5500 m. Preexisting sleep disorders were excluded via BERLIN questionnaire. All subjects performed a choice reaction test (SCHUHFRIED RT, S3) at 450 m and directly after the nights at simulated 3500 and 5500 m. We found a significant increase of cognitive reaction time with higher altitude (p = 0.026). No changes were detected in movement time (p = n.s.). Reaction time, the combined parameter of cognitive- and motoric reaction time, didn't change either (p = n.s.). Lower SpO 2 surprisingly correlated significantly with shorter cognitive reaction time (r = 0.78, p = 0.004). Sleep stage distribution and arousals at 5500 m didn't correlate with reaction time, cognitive reaction time or movement time. Sleep in hypoxia does not seem to affect reaction time to simple tasks. The component of cognitive reaction time is increasingly delayed whereas motoric reaction time seems not to be affected. Low SpO 2 and arousals are not related to increased cognitive reaction time therefore the causality remains unclear. The fact of increased cognitive reaction time after sleep in hypoxia, considering high altitude workers and mountaineering operations with overnight stays, should be further investigated.

Dissolution Front Instabilities in Reacting Porous Media

NASA Astrophysics Data System (ADS)

Raoof, Amir; Spiers, Chris; Hassanizadeh, Majid

2013-04-01

The main objective of this research is to gain a better understanding of the relation between regime of reaction and dissolution front instability, leading to formation of channels or wormholes. Potential applications are geological sequestration of CO2 and acid-gas injection during enhanced oil recovery. The microscopic pore space is modeled using a multi-directional pore network, allowing for a distribution of pore coordination number, together with distribution of pore sizes. In order to simulate transport of multi-component chemical species, mass balance equations are solved within each element of the network (i.e., pore body and pore throat). We have considered advective and diffusive transport processes within the pore spaces together with multi-component chemical reactions, including both equilibrium and kinetic reactions. Using dimensionless scaling groups (such as Damköhler number and Péclet-Damköhler number) we characterized the dissolution front behavior, and by averaging over the network domain we calculated the evolution of porosity and permeability as well as flux-averaged concentration breakthrough curves. We obtain constitutive relations linking porosity and permeability, under conditions relevant to geological storage of CO2. Effect of distribution of reactive minerals is also evaluated and regime of reaction is shown to play a key role.

Metabolic networks in motion: 13C-based flux analysis

PubMed Central

Sauer, Uwe

2006-01-01

Many properties of complex networks cannot be understood from monitoring the components—not even when comprehensively monitoring all protein or metabolite concentrations—unless such information is connected and integrated through mathematical models. The reason is that static component concentrations, albeit extremely informative, do not contain functional information per se. The functional behavior of a network emerges only through the nonlinear gene, protein, and metabolite interactions across multiple metabolic and regulatory layers. I argue here that intracellular reaction rates are the functional end points of these interactions in metabolic networks, hence are highly relevant for systems biology. Methods for experimental determination of metabolic fluxes differ fundamentally from component concentration measurements; that is, intracellular reaction rates cannot be detected directly, but must be estimated through computer model-based interpretation of stable isotope patterns in products of metabolism. PMID:17102807

Reductive smelting of spent lead-acid battery colloid sludge in a molten Na2CO3 salt

NASA Astrophysics Data System (ADS)

Hu, Yu-jie; Tang, Chao-bo; Tang, Mo-tang; Chen, Yong-ming

2015-08-01

Lead extraction from spent lead-acid battery paste in a molten Na2CO3 salt containing ZnO as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, ZnO and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the ZnO dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were PbSO4→Pb and PbSO4→ZnS, respectively. Sulfur was fixed in the form of ZnS, whereas the molten salt did not react with other components, serving only as a reaction medium.

Brittle Materials Design, High Temperature Gas Turbine

DTIC Science & Technology

1975-04-01

was directed toward fabricating flaw- free one-piece first stage stators using a silicon metal powder injection molding composition yielding reaction...process was used because this composition utilizes thermoset polymers which cannot be handled on available injection molding equipment. Silicon...molded of several compositions incorporating slight variations. Some of the components molded had completely filled the die cavity and appeared

Directed evolution of artificial metalloenzymes for in vivo metathesis

NASA Astrophysics Data System (ADS)

Jeschek, Markus; Reuter, Raphael; Heinisch, Tillmann; Trindler, Christian; Klehr, Juliane; Panke, Sven; Ward, Thomas R.

2016-09-01

The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions. For example, artificial metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist: repurposing natural metalloenzymes for abiotic transformations; in silico metalloenzyme (re-)design; and incorporation of abiotic cofactors into proteins. The third strategy offers the opportunity to design a wide variety of artificial metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein. This limits the throughput of genetic optimization schemes applied to artificial metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction without equivalent in nature. Building on previous work on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the ‘metathase’ because it offers an auspicious environment for artificial metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism.

Measurement of 1323 and 1487 keV resonances in 15N(α ,γ )19F with the recoil separator ERNA

NASA Astrophysics Data System (ADS)

Di Leva, A.; Imbriani, G.; Buompane, R.; Gialanella, L.; Best, A.; Cristallo, S.; De Cesare, M.; D'Onofrio, A.; Duarte, J. G.; Gasques, L. R.; Morales-Gallegos, L.; Pezzella, A.; Porzio, G.; Rapagnani, D.; Roca, V.; Romoli, M.; Schürmann, D.; Straniero, O.; Terrasi, F.; ERNA Collaboration

2017-04-01

Background: The origin of fluorine is a widely debated issue. Nevertheless, the 15N(α ,γ )19F reaction is a common feature among the various production channels so far proposed. Its reaction rate at relevant temperatures is determined by a number of narrow resonances together with the direct capture and the tails of the two broad resonances at Ec .m .=1323 and 1487 keV. Purpose: The broad resonances widths, Γγ and Γα, have to be measured with adequate precision in order to better determine their contribution to the 15N(α ,γ )19F stellar reaction rate. Methods: Measurement through the direct detection of the 19F recoil ions with the European Recoil separator for Nuclear Astrophysics (ERNA) were performed. The reaction was initiated by a 15N beam impinging onto a 4He windowless gas target. The observed yield of the resonances at Ec .m .=1323 and 1487 keV is used to determine their widths in the α and γ channels. Results: We show that a direct measurement of the cross section of the 15N(α ,γ )19F reaction can be successfully obtained with the recoil separator ERNA, and the widths Γγ and Γα of the two broad resonances have been determined. While a fair agreement is found with earlier determination of the widths of the 1487 keV resonance, a significant difference is found for the 1323 keV resonance Γα. Conclusions: The revision of the widths of the two more relevant broad resonances in the 15N(α ,γ )19F reaction presented in this work is the first step toward a more firm determination of the reaction rate. At present, the residual uncertainty at the temperatures of the 19F stellar nucleosynthesis is dominated by the uncertainties affecting the direct capture component and the 364 keV narrow resonance, both so far investigated only through indirect experiments.

Determination of the astrophysical 12N(p,γ)13O reaction rate from the 2H(12N,13O)n reaction and its astrophysical implications

NASA Astrophysics Data System (ADS)

Guo, B.; Su, J.; Li, Z. H.; Wang, Y. B.; Yan, S. Q.; Li, Y. J.; Shu, N. C.; Han, Y. L.; Bai, X. X.; Chen, Y. S.; Liu, W. P.; Yamaguchi, H.; Binh, D. N.; Hashimoto, T.; Hayakawa, S.; Kahl, D.; Kubono, S.; He, J. J.; Hu, J.; Xu, S. W.; Iwasa, N.; Kume, N.; Li, Z. H.

2013-01-01

The evolution of massive stars with very low-metallicities depends critically on the amount of CNO nuclides which they produce. The 12N(p,γ)13O reaction is an important branching point in the rap processes, which are believed to be alternative paths to the slow 3α process for producing CNO seed nuclei and thus could change the fate of massive stars. In the present work, the angular distribution of the 2H(12N, 13O)n proton transfer reaction at Ec.m.=8.4 MeV has been measured for the first time. Based on the Johnson-Soper approach, the square of the asymptotic normalization coefficient (ANC) for the virtual decay of 13Og.s. → 12N+p was extracted to be 3.92±1.47 fm-1 from the measured angular distribution and utilized to compute the direct component in the 12N(p,γ)13O reaction. The direct astrophysical S factor at zero energy was then found to be 0.39±0.15 keV b. By considering the direct capture into the ground state of 13O, the resonant capture via the first excited state of 13O and their interference, we determined the total astrophysical S factors and rates of the 12N(p,γ)13O reaction. The new rate is two orders of magnitude slower than that from the REACLIB compilation. Our reaction network calculations with the present rate imply that 12N(p,γ)13O will only compete successfully with the β+ decay of 12N at higher (˜2 orders of magnitude) densities than initially predicted.

An autonomous chemically fuelled small-molecule motor

NASA Astrophysics Data System (ADS)

Wilson, Miriam R.; Solà, Jordi; Carlone, Armando; Goldup, Stephen M.; Lebrasseur, Nathalie; Leigh, David A.

2016-06-01

Molecular machines are among the most complex of all functional molecules and lie at the heart of nearly every biological process. A number of synthetic small-molecule machines have been developed, including molecular muscles, synthesizers, pumps, walkers, transporters and light-driven and electrically driven rotary motors. However, although biological molecular motors are powered by chemical gradients or the hydrolysis of adenosine triphosphate (ATP), so far there are no synthetic small-molecule motors that can operate autonomously using chemical energy (that is, the components move with net directionality as long as a chemical fuel is present). Here we describe a system in which a small molecular ring (macrocycle) is continuously transported directionally around a cyclic molecular track when powered by irreversible reactions of a chemical fuel, 9-fluorenylmethoxycarbonyl chloride. Key to the design is that the rate of reaction of this fuel with reactive sites on the cyclic track is faster when the macrocycle is far from the reactive site than when it is near to it. We find that a bulky pyridine-based catalyst promotes carbonate-forming reactions that ratchet the displacement of the macrocycle away from the reactive sites on the track. Under reaction conditions where both attachment and cleavage of the 9-fluorenylmethoxycarbonyl groups occur through different processes, and the cleavage reaction occurs at a rate independent of macrocycle location, net directional rotation of the molecular motor continues for as long as unreacted fuel remains. We anticipate that autonomous chemically fuelled molecular motors will find application as engines in molecular nanotechnology.

Design and simulation of bi-directional microfluid driving systems

NASA Astrophysics Data System (ADS)

Jen, Chun-Ping; Lin, Yu-Cheng

2002-03-01

Micro total analysis systems (μTAS) have been developed to perform a number of analytical processes involving chemical reactions, separation and sensing on a single chip. In medical and biomedical applications, μTAS must be designed considering special transport mechanisms to move samples and reagents through the microchannels in the system. For conventional micropumps, however, complicated relationships exist between the pumping mechanisms, the conditions under which the devices operate and the behavior of the multi-component fluids transported in these channels. A bi-directional microfluid driving system has been developed in this paper. This pneumatic system is an on-chip planar structure with no moving parts and does not require microfabricated heaters or electrodes. The pumping actuation is introduced to the microchannel fabricated in the chip by blowing an airflow through this device. The bi-directional driving module combines two individual components for suction and exclusion. The driving system provides a stable and flexible bi-directional microfluid driving control. The tunable parameters for adjusting the exclusion/suction ratios, such as the location of the inlet channel and the velocities of the airflow, have been observed in the numerical study. The optimal exclusion/suction ratio for the specific purpose of the driving system can be selected by changing the location of the microchannel to the reaction area for the sample/reagent. The velocity at the microchannel can be adjusted by varying the inlet velocities for the suction and exclusion components. For the presented design, no air conduit was employed to connect the servo-system to the driving system; therefore the packaging difficulty and leakage problem, which may arise in conventional systems, can be eliminated. The final airflow outlet was fixed in one direction so that it can prevent cross-contamination between the servo-system and the chip. The driving system is therefore particularly suited to microdevices for biochemical analysis.

Skeletal mechanism generation for surrogate fuels using directed relation graph with error propagation and sensitivity analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niemeyer, Kyle E.; Sung, Chih-Jen; Raju, Mandhapati P.

2010-09-15

A novel implementation for the skeletal reduction of large detailed reaction mechanisms using the directed relation graph with error propagation and sensitivity analysis (DRGEPSA) is developed and presented with examples for three hydrocarbon components, n-heptane, iso-octane, and n-decane, relevant to surrogate fuel development. DRGEPSA integrates two previously developed methods, directed relation graph-aided sensitivity analysis (DRGASA) and directed relation graph with error propagation (DRGEP), by first applying DRGEP to efficiently remove many unimportant species prior to sensitivity analysis to further remove unimportant species, producing an optimally small skeletal mechanism for a given error limit. It is illustrated that the combination ofmore » the DRGEP and DRGASA methods allows the DRGEPSA approach to overcome the weaknesses of each, specifically that DRGEP cannot identify all unimportant species and that DRGASA shields unimportant species from removal. Skeletal mechanisms for n-heptane and iso-octane generated using the DRGEP, DRGASA, and DRGEPSA methods are presented and compared to illustrate the improvement of DRGEPSA. From a detailed reaction mechanism for n-alkanes covering n-octane to n-hexadecane with 2115 species and 8157 reactions, two skeletal mechanisms for n-decane generated using DRGEPSA, one covering a comprehensive range of temperature, pressure, and equivalence ratio conditions for autoignition and the other limited to high temperatures, are presented and validated. The comprehensive skeletal mechanism consists of 202 species and 846 reactions and the high-temperature skeletal mechanism consists of 51 species and 256 reactions. Both mechanisms are further demonstrated to well reproduce the results of the detailed mechanism in perfectly-stirred reactor and laminar flame simulations over a wide range of conditions. The comprehensive and high-temperature n-decane skeletal mechanisms are included as supplementary material with this article. (author)« less

Template-Directed Ligation of Peptides to Oligonucleotides

NASA Technical Reports Server (NTRS)

Bruick, Richard K.; Dawson, Philip E.; Kent, Stephen BH; Usman, Nassim; Joyce, Gerald F.

1996-01-01

Synthetic oligonucleotides and peptides have enjoyed a wide range of applications in both biology and chemistry. As a consequence, oligonucleotide-peptide conjugates have received considerable attention, most notably in the development of antisense constructs with improved pharmacological properties. In addition, oligonucleotide-peptide conjugates have been used as molecular tags, in the assembly of supramolecular arrays and in the construction of encoded combinatorial libraries. To make these chimeric molecules more accessible for a broad range of investigations, we sought to develop a facile method for joining fully deprotected oligonucleotides and peptides through a stable amide bond linkage. Furthermore, we wished to make this ligation reaction addressable, enabling one to direct the ligation of specific oligonucleotide and peptide components.To confer specificity and accelerate the rate of the reaction, the ligation process was designed to be dependent on the presence of a complementary oligonucleotide template.

Batch fabrication of polymer microfluidic cartridges for QCM sensor packaging by direct bonding

NASA Astrophysics Data System (ADS)

Sandström, Niklas; Zandi Shafagh, Reza; Gylfason, Kristinn B.; Haraldsson, Tommy; van der Wijngaart, Wouter

2017-12-01

Quartz crystal microbalance (QCM) sensing is an established technique commonly used in laboratory based life-science applications. However, the relatively complex, multi-part design and multi-step fabrication and assembly of state-of-the-art QCM cartridges make them unsuited for disposable applications such as point-of-care (PoC) diagnostics. In this work, we present the uncomplicated manufacturing of QCMs in polymer microfluidic cartridges. Our novel approach comprises two key innovations: the batch reaction injection molding of microfluidic parts; and the integration of the cartridge components by direct, unassisted bonding. We demonstrate molding of batches of 12 off-stoichiometry thiol-ene epoxy polymer (OSTE+) polymer parts in a single molding cycle using an adapted reaction injection molding process; and the direct bonding of the OSTE+  parts to other OSTE+  substrates, to printed circuit boards, and to QCMs. The microfluidic QCM OSTE+  cartridges were successfully evaluated in terms of liquid sealing as well as electrical properties, and the sensor performance characteristics are on par with those of a commercially available QCM biosensor cartridge. The simplified manufacturing of QCM sensors with maintained performance potentializes novel application areas, e.g. as disposable devices in a point of care setting. Moreover, our results can be extended to simplifying the fabrication of other microfluidic devices with multiple heterogeneously integrated components.

Precise tuning in platinum-nickel/nickel sulfide interface nanowires for synergistic hydrogen evolution catalysis

PubMed Central

Wang, Pengtang; Zhang, Xu; Zhang, Jin; Wan, Sheng; Guo, Shaojun; Lu, Gang; Yao, Jianlin; Huang, Xiaoqing

2017-01-01

Comprising abundant interfaces, multicomponent heterostructures can integrate distinct building blocks into single entities and yield exceptional functionalities enabled by the synergistic components. Here we report an efficient approach to construct one-dimensional metal/sulfide heterostructures by directly sulfuring highly composition-segregated platinum-nickel nanowires. The heterostructures possess a high density of interfaces between platinum-nickel and nickel sulfide components, which cooperate synergistically towards alkaline hydrogen evolution reaction. The platinum-nickel/nickel sulfide heterostructures can deliver a current density of 37.2 mA cm−2 at an overpotential of 70 mV, which is 9.7 times higher than that of commercial Pt/C. The heterostructures also offer enhanced stability revealed by long-term chronopotentiometry measurements. The present work highlights a potentially powerful interface-engineering strategy for designing multicomponent heterostructures with advanced performance in hydrogen evolution reaction and beyond. PMID:28239145

Component mobility at 900 °C and 18 kbar from experimentally grown coronas in a natural gabbro

NASA Astrophysics Data System (ADS)

Keller, Lukas M.; Wunder, Bernd; Rhede, Dieter; Wirth, Richard

2008-09-01

Several approximately 100-μm-wide reaction zones were grown under experimental conditions of 900 °C and 18 kbar along former olivine-plagioclase contacts in a natural gabbro. The reaction zone comprises two distinct domains: (i) an irregularly bounded zone with idiomorphic grains of zoisite and minor corundum and kyanite immersed in a melt developed at the plagioclase side and (ii) a well-defined reaction band comprising a succession of mineral layers forming a corona structure around olivine. Between the olivine and the plagioclase reactant phases we observe the following layer sequence: olivine|pyroxene|garnet|partially molten domain|plagioclase. Within the pyroxene layer two micro-structurally distinct layers comprising enstatite and clinopyroxene can be discerned. Chemical potential gradients persisted for the CaO, Al 2O 3, SiO 2, MgO and FeO components, which drove diffusion of Ca, Al and Si bearing species from the garnet-matrix interface to the pyroxene-olivine interface and diffusion of Mg- and Fe-bearing species in the opposite direction. The systematic mineralogical organization and chemical zoning across the corona suggest that the olivine corona was formed by a "diffusion-controlled" reaction. We estimate a set of diffusion coefficients and conclude that LAlAl < LCaCa < ( LSiSi, LFeFe) < LMgMg during reaction rim growth.

A mesoscopic reaction rate model for shock initiation of multi-component PBX explosives.

PubMed

Liu, Y R; Duan, Z P; Zhang, Z Y; Ou, Z C; Huang, F L

2016-11-05

The primary goal of this research is to develop a three-term mesoscopic reaction rate model that consists of a hot-spot ignition, a low-pressure slow burning and a high-pressure fast reaction terms for shock initiation of multi-component Plastic Bonded Explosives (PBX). Thereinto, based on the DZK hot-spot model for a single-component PBX explosive, the hot-spot ignition term as well as its reaction rate is obtained through a "mixing rule" of the explosive components; new expressions for both the low-pressure slow burning term and the high-pressure fast reaction term are also obtained by establishing the relationships between the reaction rate of the multi-component PBX explosive and that of its explosive components, based on the low-pressure slow burning term and the high-pressure fast reaction term of a mesoscopic reaction rate model. Furthermore, for verification, the new reaction rate model is incorporated into the DYNA2D code to simulate numerically the shock initiation process of the PBXC03 and the PBXC10 multi-component PBX explosives, and the numerical results of the pressure histories at different Lagrange locations in explosive are found to be in good agreements with previous experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

Astrophysical S factor for the radiative capture {sup 12}N(p,{gamma}){sup 13}O determined from the {sup 14}N({sup 12}N,{sup 13}O){sup 13}C proton transfer reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banu, A.; Al-Abdullah, T.; Fu, C.

2009-02-15

The cross section of the radiative proton capture reaction on the drip line nucleus {sup 12}N was investigated using the asymptotic normalization coefficient (ANC) method. We have used the {sup 14}N({sup 12}N,{sup 13}O){sup 13}C proton transfer reaction at 12 MeV/nucleon to extract the ANC for {sup 13}O{yields}{sup 12}N+p and calculate from it the direct component of the astrophysical S factor of the {sup 12}N(p,{gamma}){sup 13}O reaction. The optical potentials used and the distorted-wave Born approximation analysis of the proton transfer reaction are discussed. For the entrance channel, the optical potential was inferred from an elastic scattering measurement carried out atmore » the same time as the transfer measurement. From the transfer, we determined the square of the ANC, C{sub p{sub 1/2}}{sup 2}({sup 13}O{sub g.s.})=2.53{+-}0.30 fm{sup -1}, and hence a value of 0.33(4) keV b was obtained for the direct astrophysical S factor at zero energy. Constructive interference at low energies between the direct and resonant captures leads to an enhancement of S{sub total}(0)=0.42(6) keV b. The {sup 12}N(p,{gamma}){sup 13}O reaction was investigated in relation to the evolution of hydrogen-rich massive Population III stars, for the role that it may play in the hot pp-chain nuclear burning processes, possibly occurring in such objects.« less

Fusion pumped light source

DOEpatents

Pappas, Daniel S.

1989-01-01

Apparatus is provided for generating energy in the form of light radiation. A fusion reactor is provided for generating a long, or continuous, pulse of high-energy neutrons. The neutron flux is coupled directly with the lasing medium. The lasing medium includes a first component selected from Group O of the periodic table of the elements and having a high inelastic scattering cross section. Gamma radiation from the inelastic scattering reactions interacts with the first component to excite the first component, which decays by photon emission at a first output wavelength. The first output wavelength may be shifted to a second output wavelength using a second liquid component responsive to the first output wavelength. The light outputs may be converted to a coherent laser output by incorporating conventional optics adjacent the laser medium.

A comparison and update of direct kinematic-kinetic models of leg stiffness in human running.

PubMed

Liew, Bernard X W; Morris, Susan; Masters, Ashleigh; Netto, Kevin

2017-11-07

Direct kinematic-kinetic modelling currently represents the "Gold-standard" in leg stiffness quantification during three-dimensional (3D) motion capture experiments. However, the medial-lateral components of ground reaction force and leg length have been neglected in current leg stiffness formulations. It is unknown if accounting for all 3D would alter healthy biologic estimates of leg stiffness, compared to present direct modelling methods. This study compared running leg stiffness derived from a new method (multiplanar method) which includes all three Cartesian axes, against current methods which either only include the vertical axis (line method) or only the plane of progression (uniplanar method). Twenty healthy female runners performed shod overground running at 5.0 m/s. Three-dimensional motion capture and synchronised in-ground force plates were used to track the change in length of the leg vector (hip joint centre to centre of pressure) and resultant projected ground reaction force. Leg stiffness was expressed as dimensionless units, as a percentage of an individual's bodyweight divided by standing leg length (BW/LL). Leg stiffness using the line method was larger than the uniplanar method by 15.6%BW/LL (P < .001), and multiplanar method by 24.2%BW/LL (P < .001). Leg stiffness from the uniplanar method was larger than the multiplanar method by 8.5%BW/LL (6.5 kN/m) (P < .001). The inclusion of medial-lateral components significantly increased leg deformation magnitude, accounting for the reduction in leg stiffness estimate with the multiplanar method. Given that limb movements typically occur in 3D, the new multiplanar method provides the most complete accounting of all force and length components in leg stiffness calculation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hybrid discrete/continuum algorithms for stochastic reaction networks

DOE PAGES

Safta, Cosmin; Sargsyan, Khachik; Debusschere, Bert; ...

2014-10-22

Direct solutions of the Chemical Master Equation (CME) governing Stochastic Reaction Networks (SRNs) are generally prohibitively expensive due to excessive numbers of possible discrete states in such systems. To enhance computational efficiency we develop a hybrid approach where the evolution of states with low molecule counts is treated with the discrete CME model while that of states with large molecule counts is modeled by the continuum Fokker-Planck equation. The Fokker-Planck equation is discretized using a 2nd order finite volume approach with appropriate treatment of flux components to avoid negative probability values. The numerical construction at the interface between the discretemore » and continuum regions implements the transfer of probability reaction by reaction according to the stoichiometry of the system. As a result, the performance of this novel hybrid approach is explored for a two-species circadian model with computational efficiency gains of about one order of magnitude.« less

Focus on fresh frozen plasma - facilitating optimal management of bleeding through collaboration between clinicians and transfusion specialists on component specifications.

PubMed

MacLennan, Sheila

2016-01-01

A symposium on plasma for direct clinical use was held in September 2015 by the European directorate for the quality of medicines and healthcare (EDQM) in order to consider changes to the Council of Europe guide to the preparation, use and quality assurance of blood components monographs on plasma components. The programme reviewed use of plasma in various settings, novel components, adverse reactions, manufacturing and quality monitoring issues. The main requirement identified was that plasma should be made available to support early transfusion in the trauma/massive haemorrhage setting. Further guidance on component manufacturing and reviewing of quality monitoring requirements will also be addressed. A working group has been established to review component monographs and other advice in the guide relating to plasma components, with the aim of providing optimal components to support clinical management of patients requiring plasma. Crown Copyright © 2016. Published by Elsevier Masson SAS. All rights reserved.

Impact of Site-Directed Mutant Luciferase on Quantitative Green and Orange/Red Emission Intensities in Firefly Bioluminescence

NASA Astrophysics Data System (ADS)

Wang, Yu; Akiyama, Hidefumi; Terakado, Kanako; Nakatsu, Toru

2013-08-01

Firefly bioluminescence has attracted great interest because of its high quantum yield and intriguing modifiable colours. Modifications to the structure of the enzyme luciferase can change the emission colour of firefly bioluminescence, and the mechanism of the colour change has been intensively studied by biochemists, structural biologists, optical physicists, and quantum-chemistry theorists. Here, we report on the quantitative spectra of firefly bioluminescence catalysed by wild-type and four site-directed mutant luciferases. While the mutation caused different emission spectra, the spectra differed only in the intensity of the green component (λmax ~ 560 nm). In contrast, the orange (λmax ~ 610 nm) and red (λmax ~ 650 nm) components present in all the spectra were almost unaffected by the modifications to the luciferases and changes in pH. Our results reveal that the intensity of the green component is the unique factor that is influenced by the luciferase structure and other reaction conditions.

Photochromic, electrochromic, photoelectrochromic and photovoltaic devices

DOEpatents

Kostecki, Robert; McLarnon, Frank R.

2000-01-01

A light activated photoelectrochromic device is formed of a two-component system formed of a photoactive charge carrier generating material and electrochromic material (plus an elecrolyte). Light interacts with a semiconductive material to generate hole-electron charge carriers which cause a redox reaction in the electrochromic material. One device is formed of hydrated nickel oxide as the electrochromic layer and polycrystalline titanium dioxide as the charge generating material. The materials may be formed as discrete layers or mixed together. Because of the direct charge transfer between the layers, a circuit to apply a voltage to drive the electrochromic reaction is not required, although one can be used to enhance the reaction. The hydrated nickel oxide-titanium dioxide materials can also be used to form a photovoltaic device for generating electricity.

Effect of nitrate, carbonate/bicarbonate, humic acid, and H2O2 on the kinetics and degradation mechanism of Bisphenol-A during UV photolysis.

PubMed

Kang, Young-Min; Kim, Moon-Kyung; Zoh, Kyung-Duk

2018-08-01

In this study, the effects of natural water components (nitrate, carbonate/bicarbonate, and humic acid) on the kinetics and degradation mechanisms of bisphenol A (BPA) during UV-C photolysis and UV/H 2 O 2 reaction were examined. The presence of NO 3 - (0.04-0.4 mM) and CO 3 2- /HCO 3 - (0.4-4 mM) ions increased BPA degradation during UV photolysis. Humic acid less than 3 mg/L promoted BPA degradation, but greater than 3 mg/L of humic acid inhibited BPA degradation. During the UV/H 2 O 2 reaction, all water matrix components acted as radical scavengers in the order of humic acid > CO 3 2- /HCO 3 -  > NO 3 - . All of the degradation reactions agreed with the pseudo-first-order kinetics. While eight byproducts (m/z = 122, 136, 139, 164, 181, 244, 273, 289) were identified in UV-C/NO 3 - photolysis reaction, four (m/z = 122, 136, 164, 244) and three byproducts (m/z = 122, 136, 164) were observed during UV-C/NO 3 - /CO 3 2- /HCO 3 - and UV-C/CO 3 2- /HCO 3 - reactions. Nitrogenated and hydrogenated byproducts were first observed during the UV-C/NO 3 - photolysis, but only hydrogenated byproducts as adducts were detected during the UV-C/NO 3 - /CO 3 2- /HCO 3 - photolysis. Nitrogenated and hydrogenated byproducts were formed in the early stage of degradation by OH or NO 2 radicals, and these byproducts were subsequently degraded into smaller compounds with further reaction during UV-C/NO 3 - and UV-C/NO 3 - /CO 3 2- /HCO 3 - reactions. In contrast, BPA was directly degraded into smaller compounds by β-scission of the isopropyl group by CO 3 - /HCO 3 radicals during UV-C/CO 3 2- /HCO 3 - reaction. Our results imply that the water components can change the degradation mechanism of BPA during UV photolysis. Copyright © 2018 Elsevier Ltd. All rights reserved.

Emotional Granularity and Borderline Personality Disorder

PubMed Central

Suvak, Michael K.; Litz, Brett T.; Sloan, Denise M.; Zanarini, Mary C.; Barrett, Lisa Feldman; Hofmann, Stefan G.

2011-01-01

This study examined the affective dysregulation component of borderline personality disorder (BPD) from an emotional granularity perspective, which refers to the specificity in which one represents emotions. Forty-six female participants meeting criteria for BPD and 51 female control participants without BPD and Axis I pathology completed tasks that assessed the degree to which participants incorporated information about valence (pleasant–unpleasant) and arousal (calm–activated) in their semantic/conceptual representations of emotions and in using labels to represent emotional reactions. As hypothesized, participants with BPD emphasized valence more and arousal less than control participants did when using emotion terms to label their emotional reactions. Implications and future research directions are discussed. PMID:21171723

Visualizing autophosphorylation in histidine kinases.

PubMed

Casino, Patricia; Miguel-Romero, Laura; Marina, Alberto

2014-01-01

Reversible protein phosphorylation is the most widespread regulatory mechanism in signal transduction. Autophosphorylation in a dimeric sensor histidine kinase is the first step in two-component signalling, the predominant signal-transduction device in bacteria. Despite being the most abundant sensor kinases in nature, the molecular bases of the histidine kinase autophosphorylation mechanism are still unknown. Furthermore, it has been demonstrated that autophosphorylation can occur in two directions, cis (intrasubunit) or trans (intersubunit) within the dimeric histidine kinase. Here, we present the crystal structure of the complete catalytic machinery of a chimeric histidine kinase. The structure shows an asymmetric histidine kinase dimer where one subunit is caught performing the autophosphorylation reaction. A structure-guided functional analysis on HK853 and EnvZ, two prototypical cis- and trans-phosphorylating histidine kinases, has allowed us to decipher the catalytic mechanism of histidine kinase autophosphorylation, which seems to be common independently of the reaction directionality.

Mechanism of early postradiation changes in intensity of spontaneous chemoluminescence of blood serum. [X rays; rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baraboi, V.A.; Orel, V.E.; Sribnaya, A.F.

The effects of epinephrine and hydrocortisone on rat blood serum CL were tested under model conditions to analyze the possible role of biologically active compounds in the pathogenesis of the described postradiation changes. Injection of epinephrine in a concentration of 50 ..mu..g/kg, induced a rapid and substantial decline of CL followed by normalization. Addition of epinephrine directly to bovine blood serum in a model experiment, with access of atmospheric oxygen, caused progressive increase in CL with increase in dosage and exposure time. This experiment demonstrates the capacity of epinephrine to interact directly with oxygen, acting as a watersoluble antioxidant. Intraperitonealmore » injections of hydrocortisone revealed a marked decline of CL under these conditions. Direct addition of hydrocortisone to blood serum under model conditions did not affect its CL. Thus, the antioxidant effect of hydrocortisone is mediated in nature. The data indicate that postradiation increase in incretion of epinephrine and corticosteroids can explain the decrease in blood serum CL of rats exposed to lethal radiation. Since the reaction of the adrenosympathetic and adrenohypophyseal systems to total-body irradiation is a manifestation of a nonspecific stress reaction; the decreased intensity of blood serum CL is probably also a component of this reaction. (ERB)« less

Binding Isotherms and Time Courses Readily from Magnetic Resonance.

PubMed

Xu, Jia; Van Doren, Steven R

2016-08-16

Evidence is presented that binding isotherms, simple or biphasic, can be extracted directly from noninterpreted, complex 2D NMR spectra using principal component analysis (PCA) to reveal the largest trend(s) across the series. This approach renders peak picking unnecessary for tracking population changes. In 1:1 binding, the first principal component captures the binding isotherm from NMR-detected titrations in fast, slow, and even intermediate and mixed exchange regimes, as illustrated for phospholigand associations with proteins. Although the sigmoidal shifts and line broadening of intermediate exchange distorts binding isotherms constructed conventionally, applying PCA directly to these spectra along with Pareto scaling overcomes the distortion. Applying PCA to time-domain NMR data also yields binding isotherms from titrations in fast or slow exchange. The algorithm readily extracts from magnetic resonance imaging movie time courses such as breathing and heart rate in chest imaging. Similarly, two-step binding processes detected by NMR are easily captured by principal components 1 and 2. PCA obviates the customary focus on specific peaks or regions of images. Applying it directly to a series of complex data will easily delineate binding isotherms, equilibrium shifts, and time courses of reactions or fluctuations.

Cortical Components of Reaction-Time during Perceptual Decisions in Humans.

PubMed

Dmochowski, Jacek P; Norcia, Anthony M

2015-01-01

The mechanisms of perceptual decision-making are frequently studied through measurements of reaction time (RT). Classical sequential-sampling models (SSMs) of decision-making posit RT as the sum of non-overlapping sensory, evidence accumulation, and motor delays. In contrast, recent empirical evidence hints at a continuous-flow paradigm in which multiple motor plans evolve concurrently with the accumulation of sensory evidence. Here we employ a trial-to-trial reliability-based component analysis of encephalographic data acquired during a random-dot motion task to directly image continuous flow in the human brain. We identify three topographically distinct neural sources whose dynamics exhibit contemporaneous ramping to time-of-response, with the rate and duration of ramping discriminating fast and slow responses. Only one of these sources, a parietal component, exhibits dependence on strength-of-evidence. The remaining two components possess topographies consistent with origins in the motor system, and their covariation with RT overlaps in time with the evidence accumulation process. After fitting the behavioral data to a popular SSM, we find that the model decision variable is more closely matched to the combined activity of the three components than to their individual activity. Our results emphasize the role of motor variability in shaping RT distributions on perceptual decision tasks, suggesting that physiologically plausible computational accounts of perceptual decision-making must model the concurrent nature of evidence accumulation and motor planning.

Homogeneous catalyst formulations for methanol production

DOEpatents

Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

1991-02-12

There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.-), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

Homogeneous catalyst formulations for methanol production

DOEpatents

Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

1990-01-01

There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.13 ), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

Enhancing the methanol tolerance of platinum nanoparticles for the cathode reaction of direct methanol fuel cells through a geometric design.

PubMed

Feng, Yan; Ye, Feng; Liu, Hui; Yang, Jun

2015-11-18

Mastery over the structure of nanoparticles might be an effective way to enhance their performance for a given application. Herein we demonstrate the design of cage-bell nanostructures to enhance the methanol tolerance of platinum (Pt) nanoparticles while remaining their catalytic activity for oxygen reduction reaction. This strategy starts with the synthesis of core-shell-shell nanoparticles with Pt and silver (Ag) residing respectively in the core and inner shell regions, which are then agitated with saturated sodium chloride (NaCl) solution to eliminate the Ag component from the inner shell region, leading to the formation of bimetallic nanoparticles with a cage-bell structure, defined as a movable Pt core enclosed by a metal shell with nano-channels, which exhibit superior methanol-tolerant property in catalyzing oxygen reduction reaction due to the different diffusion behaviour of methanol and oxygen in the porous metal shell of cage-bell structured nanoparticles. In particular, the use of remarkably inexpensive chemical agent (NaCl) to promote the formation of cage-bell structured particles containing a wide spectrum of metal shells highlights its engineering merit to produce highly selective electrocatalysts on a large scale for the cathode reaction of direct methanol fuel cells.

Quantitative modeling of the reaction/diffusion kinetics of two-chemistry photopolymers

NASA Astrophysics Data System (ADS)

Kowalski, Benjamin Andrew

Optically driven diffusion in photopolymers is an appealing material platform for a broad range of applications, in which the recorded refractive index patterns serve either as images (e.g. data storage, display holography) or as optical elements (e.g. custom GRIN components, integrated optical devices). A quantitative understanding of the reaction/diffusion kinetics is difficult to obtain directly, but is nevertheless necessary in order to fully exploit the wide array of design freedoms in these materials. A general strategy for characterizing these kinetics is proposed, in which key processes are decoupled and independently measured. This strategy enables prediction of a material's potential refractive index change, solely on the basis of its chemical components. The degree to which a material does not reach this potential reveals the fraction of monomer that has participated in unwanted reactions, reducing spatial resolution and dynamic range. This approach is demonstrated for a model material similar to commercial media, achieving quantitative predictions of index response over three orders of exposure dose (~1 to ~103 mJ cm-2) and three orders of feature size (0.35 to 500 microns). The resulting insights enable guided, rational design of new material formulations with demonstrated performance improvement.

The efficiency of non-photochemical fluorescence quenching by cation radicals in photosystem II reaction centers.

PubMed

Paschenko, V Z; Churin, A A; Gorokhov, V V; Grishanova, N P; Korvatovskii, B N; Maksimov, E G; Mamedov, M D

2016-12-01

In a direct experiment, the rate constants of photochemical k p and non-photochemical k p + quenching of the chlorophyll fluorescence have been determined in spinach photosystem II (PS II) membrane fragments, oxygen-evolving PS II core, as well as manganese-depleted PS II particles using pulse fluorimetry. In the dark-adapted reaction center(s) (RC), the fluorescence decay kinetics of the antenna were measured at low-intensity picosecond pulsed excitation. To create a "closed" P680 + Q A - state, RCs were illuminated by high-intensity actinic flash 8 ns prior to the measuring flash. The obtained data were approximated by the sum of two decaying exponents. It was found that the antennae fluorescence quenching efficiency by the oxidized photoactive pigment of RC P680 + was about 1.5 times higher than that of the neutral P680 state. These results were confirmed by a single-photon counting technique, which allowed to resolve the additional slow component of the fluorescence decay. Slow component was assigned to the charge recombination of P680 + Pheo - in PS II RC. Thus, for the first time, the ratio k p + /k p  ≅ 1.5 was found directly. The mechanism of the higher efficiency of non-photochemical quenching comparing to photochemical quenching is discussed.

Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

ERIC Educational Resources Information Center

Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

2013-01-01

A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

The diagnostic value of component-resolved diagnostics in peanut allergy in children attending a Regional Paediatric Allergology Clinic.

PubMed

van Veen, Leonieke N; Heron, Michiel; Batstra, Manou; van Haard, Paul M M; de Groot, Hans

2016-06-02

To date, diagnosing food allergies in children still presents a diagnostic dilemma, leading to uncertainty concerning the definite diagnosis of peanut allergy, as well as to the need for strict diets and the potential need for adrenalin auto-injectors. This uncertainty in particular is thought to contribute to a lower quality of life. In the diagnostic process double-blind food challenges are considered the gold standard, but they are time-consuming as well as potentially hazardous. Other diagnostic tests have been extensively studied and among these component-resolved diagnostics appeared to present a promising alternative: Ara h2, a peanut storage protein in previous studies showed to have a significant predictive value. Sixty-two out of 72 children, with suspected peanut allergy were analyzed using serum specific IgE and/or skin prick tests and specific IgE to several components of peanut (Ara h 1, 2, 3, 6, 8, 9). Subsequently, double-blind food challenges were performed. The correlation between the various diagnostic tests and the overall outcome of the double-blind food challenges were studied, in particular the severity of the reaction and the eliciting dose. The double-blind provocation with peanut was positive in 33 children (53 %). There was no relationship between the eliciting dose and the severity of the reaction. A statistically significant relationship was found between the skin prick test, specific IgE directed to peanut, Ara h 1, Ara h 2 or Ara h 6, and the outcome of the food challenge test, in terms of positive or negative (P < .001). However, we did not find any relationship between sensitisation to peanut extract or the different allergen components and the severity of the reaction or the eliciting dose. There was no correlation between IgE directed to Ara h 3, Ara h 8, Ara h 9 and the clinical outcome of the food challenge. This study shows that component-resolved diagnostics is not superior to specific IgE to peanut extract or to skin prick testing. At present, it cannot replace double-blind placebo-controlled food challenges for determination of the eliciting dose or the severity of the peanut allergy in our patient group.

Hypochlorous acid-mediated oxidation of lipid components and antioxidants present in low-density lipoproteins: absolute rate constants, product analysis, and computational modeling.

PubMed

Pattison, David I; Hawkins, Clare L; Davies, Michael J

2003-04-01

Oxidation of low-density lipoproteins (LDL) is believed to contribute to the increased uptake of LDL by macrophages, which is an early event in atherosclerosis. Hypochlorous acid (HOCl) has been implicated as one of the major oxidants involved in these processes. In a previous study, the rates of reaction of HOCl with the reactive sites in proteins were investigated (Pattison, D. I., and Davies, M. J. (2001) Chem. Res. Toxicol. 14, 1453-1464). The work presented here expands on those studies to determine absolute second-order rate constants for the reactions of HOCl with various lipid components and antioxidants in aqueous solution (pH 7.4). The reactions of HOCl with phosphoryl-serine and phosphoryl-ethanolamine are rapid (k approximately 10(5) M(-)(1) s(-)(1)) and of comparable reactivity to many of the protein sites. The major products formed in these reactions are chloramines, which decay to give both nitrogen- and carbon-centered radicals. Subsequent reactions of these species may induce oxidation of the LDL lipid component. In contrast, phosphoryl-choline reacted much more slowly (k < 10(-)(2) M(-)(1) s(-)(1)). Reaction of HOCl with 3-pentenoic acid was used as a model of lipid double bonds and yielded k = 9 M(-)(1) s(-)(1). The reactions of the lipid-soluble antioxidants, alpha-tocopherol and ubiquinol-10, with HOCl were investigated with model compounds. For the reactions of HOCl with both Trolox and ubiquinol-0, k = 1.3 x 10(3) M(-)(1) s(-)(1); thus, these lipid soluble antioxidants are relatively ineffective as direct scavengers for HOCl as compared to water soluble antioxidants (e.g., ascorbate, k ca. 10(6) M(-)(1) s(-)(1)). The reaction of HOCl with hydroquinone (a simple model for ubiquinol-10) was also investigated both in aqueous solution (k = 45 M(-)(1) s(-)(1)) and in a less polar environment (k approximately 0.5 M(-)(1) s(-)(1) in THF). A computational model was developed using these kinetic parameters to predict which LDL targets are oxidized with varying molar excesses of HOCl, in both the absence and the presence of added ascorbate. The results from these models compare well with experimental data and can be used to predict the effects of HOCl-mediated oxidation on LDL composition.

Preparation of Pillar[5]arene-Based [2]Rotaxanes by a Stopper-Exchange Strategy.

PubMed

Nierengarten, Iwona; Meichsner, Eric; Holler, Michel; Pieper, Pauline; Deschenaux, Robert; Delavaux-Nicot, Béatrice; Nierengarten, Jean-François

2018-01-02

A pillar[5]arene-containing rotaxane building block bearing exchangeable stoppers has been prepared in multigram scale quantities with high yields from the reaction of 2,4-dinitrophenol (DNP) with the inclusion complex resulting from the association of dodecanedioyl chloride with 1,4-diethoxypillar[5]arene. Stopper exchange reactions have been achieved by treatment of the resulting DNP diester with various amines through an addition-elimination mechanism preventing the unthreading of the axle component during the reaction and thus preserving the [2]rotaxane structures. The resulting diamide [2]rotaxane derivatives have thus been obtained in good to excellent yields. Importantly, [2]rotaxanes difficult or impossible to prepare by direct introduction of the two stoppers in a single synthetic step are now easily available. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Why does a spinning egg rise?

NASA Astrophysics Data System (ADS)

Cross, Rod

2018-03-01

Experimental and theoretical results are presented concerning the rise of a spinning egg. It was found that an egg rises quickly while it is sliding and then more slowly when it starts rolling. The angular momentum of the egg projected in the XZ plane changed in the same direction as the friction torque, as expected, by rotating away from the vertical Z axis. The latter result does not explain the rise. However, an even larger effect arises from the Y component of the angular momentum vector. As the egg rises, the egg rotates about the Y axis, an effect that is closely analogous to rotation of the egg about the Z axis. Both effects can be described in terms of precession about the respective axes. Steady precession about the Z axis arises from the normal reaction force in the Z direction, while precession about the Y axis arises from the friction force in the Y direction. Precession about the Z axis ceases if the normal reaction force decreases to zero, and precession about the Y axis ceases if the friction force decreases to zero.

Double differential light charged particle emission cross sections for some structural fusion materials

NASA Astrophysics Data System (ADS)

Sarpün, Ismail Hakki; n, Abdullah Aydı; Tel, Eyyup

2017-09-01

In fusion reactors, neutron induced radioactivity strongly depends on the irradiated material. So, a proper selection of structural materials will have been limited the radioactive inventory in a fusion reactor. First-wall and blanket components have high radioactivity concentration due to being the most flux-exposed structures. The main objective of fusion structural material research is the development and selection of materials for reactor components with good thermo-mechanical and physical properties, coupled with low-activation characteristics. Double differential light charged particle emission cross section, which is a fundamental data to determine nuclear heating and material damages in structural fusion material research, for some elements target nuclei have been calculated by the TALYS 1.8 nuclear reaction code at 14-15 MeV neutron incident energy and compared with available experimental data in EXFOR library. Direct, compound and pre-equilibrium reaction contribution have been theoretically calculated and dominant contribution have been determined for each emission of proton, deuteron and alpha particle.

Synthesis of water-dispersed magnetic nanoparticles (H2O-DMNPs) of β-cyclodextrin modified Fe3O4 and its catalytic application in Kabachnik-Fields multicomponent reaction

NASA Astrophysics Data System (ADS)

Rostamnia, Sadegh; Doustkhah, Esmail

2015-07-01

Water-dispersed magnetic nanoparticles (H2O-DMNPs) of β-cyclodextrin modified Fe3O4 were successfully synthesized. β-Cyclodextrin acts as stabilizer and structure directing agent of Fe3O4. Subsequently, the dispersion of Fe3O4@β-CD was applied for the Kabachnik-Fields multicomponent reaction through three-component synthesis of an amine, aldehyde, and dimethylphosphonate. β-CD had also a drastic effect in accelerating the catalysis of phosphonate synthesis. By this protocol, phosphonate derivatives were synthesized in high yields and the catalyst was recycled for 10 successful runs.

Scalable Total Syntheses of N-Linked Tryptamine Dimers by Direct Indole-Aniline Coupling: Psychotrimine and Kapakahines B & F

PubMed Central

Newhouse, Timothy; Lewis, Chad A.; Eastman, Kyle J.; Baran, Phil S.

2010-01-01

This report details the invention of a method to enable syntheses of psychotrimine, 1, and the kapakahines F and B, 2 & 3, on a gram scale and in a minimum number of steps. Mechanistic inquiries are presented for the key enabling quaternization of indole at the C3 position by electrophilic attack of an activated aniline species. Excellent chemo-, regio-, and diastereoselectivities are observed for reactions with o-iodoaniline, an indole cation equivalent. Additionally, the scope of this reaction is broad with respect to the tryptamine and aniline components. The anti-cancer profiles of psychotrimine, 1, and kapakahines F and B, 2 & 3, have also been evaluated. PMID:20426477

Discovering operating modes in telemetry data from the Shuttle Reaction Control System

NASA Technical Reports Server (NTRS)

Manganaris, Stefanos; Fisher, Doug; Kulkarni, Deepak

1994-01-01

This paper addresses the problem of detecting and diagnosing faults in physical systems, for which suitable system models are not available. An architecture is proposed that integrates the on-line acquisition and exploitation of monitoring and diagnostic knowledge. The focus is on the component of the architecture that discovers classes of behaviors with similar characteristics by observing a system in operation. A characterization of behaviors based on best fitting approximation models is investigated. An experimental prototype has been implemented to test it. Preliminary results in diagnosing faults of the reaction control system of the space shuttle are presented. The merits and limitations of the approach are identified and directions for future work are set.

Insight into association reactions on metal surfaces: Density-functional theory studies of hydrogenation reactions on Rh(111)

NASA Astrophysics Data System (ADS)

Liu, Zhi-Pan; Hu, P.; Lee, Ming-Hsien

2003-09-01

Hydrogenation reaction, as one of the simplest association reactions on surfaces, is of great importance both scientifically and technologically. They are essential steps in many industrial processes in heterogeneous catalysis, such as ammonia synthesis (N2+3H2→2NH3). Many issues in hydrogenation reactions remain largely elusive. In this work, the NHx (x=0,1,2) hydrogenation reactions (N+H→NH, NH+H→NH2 and NH2+H→NH3) on Rh(111) are used as a model system to study the hydrogenation reactions on metal surfaces in general using density-functional theory. In addition, C and O hydrogenation (C+H→CH and O+H→OH) and several oxygenation reactions, i.e., C+O, N+O, O+O reactions, are also calculated in order to provide a further understanding of the barrier of association reactions. The reaction pathways and the barriers of all these reactions are determined and reported. For the C, N, NH, and O hydrogenation reactions, it is found that there is a linear relationship between the barrier and the valency of R (R=C, N, NH, and O). Detailed analyses are carried out to rationalize the barriers of the reactions, which shows that: (i) The interaction energy between two reactants in the transition state plays an important role in determining the trend in the barriers; (ii) there are two major components in the interaction energy: The bonding competition and the direct Pauli repulsion; and (iii) the Pauli repulsion effect is responsible for the linear valency-barrier trend in the C, N, NH, and O hydrogenation reactions. For the NH2+H reaction, which is different from other hydrogenation reactions studied, the energy cost of the NH2 activation from the IS to the TS is the main part of the barrier. The potential energy surface of the NH2 on metal surfaces is thus crucial to the barrier of NH2+H reaction. Three important factors that can affect the barrier of association reactions are generalized: (i) The bonding competition effect; (ii) the local charge densities of the reactants along the reaction direction; and (iii) the potential energy surface of the reactants on the surface. The lowest energy pathway for a surface association reaction should correspond to the one with the best compromise of these three factors.

Potential for Biodegradation of the Alkaline Hydrolysis End Products of TNT and RDX

DTIC Science & Technology

2007-11-01

Bellco Glass, Inc. (Vineland, NJ). The stainless steel , deflected point needles used in sparging (18 G, 6 in. and 12 in.) were manufactured by Popper and...12 Figure 4. Gas sparging of anaerobic cultures showing the direction of flow of the CO2- free carrier gas through the sample...determine if any reaction components exhibited unpaired electron spins, which would indicate a free radical. EPR results suggested that a single

Development of Carbon and Sulphur Tolerant Anodes of Solid Oxide Fuel Cells

DTIC Science & Technology

2010-01-14

LSCM/YSZ) composite anode is investigated in detail for the direct utilization of ethanol and methane (the main component of natural gas) in SOFCs...Impregnation of Pd nanoparticles significantly promotes the electrocatalytic activity of LSCM/YSZ composite anodes for the ethanol and methane... electrooxidation reaction. At 800°C, the electrode polarization resistance for the methane oxidation is reduced by a factor of 3 after impregnation of 0.10

Polarization effects in the reactions p + 3 He → π+ + 4 He, π+ + 4 He → p + 3 He and quantum character of spin correlations in the final (p, 3 He) system

NASA Astrophysics Data System (ADS)

Lyuboshitz, Valery V.; Lyuboshitz, Vladimir L.

2017-12-01

The general consequences of T invariance for the direct and inverse binary reactions a + b → c + d, c + d → a + b with spin-1/2 particles a, b and unpolarized particles c, d are considered. Using the formalism of helicity amplitudes, the polarization effects are studied in the reaction p + 3 He → π+ + 4 He and in the inverse process π+ + 4 He → p + 3 He. It is shown that in the reaction π + + 4 He → p + 3 He the spins of the final proton and 3 He nucleus are strongly correlated. A structural expression through helicity amplitudes, corresponding to arbitrary emission angles, is obtained for the correlation tensor. It is established that in the reaction π + + 4 He → p + 3 He one of the “classical” incoherence inequalities of the Bell type for diagonal components of the correlation tensor is necessarily violated and, thus, the spin correlations of the final particles have the strongly pronounced quantum character.

Rapid Neutrino Cooling in the Neutron Star MXB 1659-29.

PubMed

Brown, Edward F; Cumming, Andrew; Fattoyev, Farrukh J; Horowitz, C J; Page, Dany; Reddy, Sanjay

2018-05-04

We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n+n→n+p+e^{-}+ν[over ¯]_{e} and inverse) and is consistent with the direct Urca (n→p+e^{-}+ν[over ¯]_{e} and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.

Rapid Neutrino Cooling in the Neutron Star MXB 1659-29

NASA Astrophysics Data System (ADS)

Brown, Edward F.; Cumming, Andrew; Fattoyev, Farrukh J.; Horowitz, C. J.; Page, Dany; Reddy, Sanjay

2018-05-01

We show that the neutron star in the transient system MXB 1659-29 has a core neutrino luminosity that substantially exceeds that of the modified Urca reactions (i.e., n +n →n +p +e-+ν¯ e and inverse) and is consistent with the direct Urca (n →p +e-+ν¯e and inverse) reaction occurring in a small fraction of the core. Observations of the thermal relaxation of the neutron star crust following 2.5 yr of accretion allow us to measure the energy deposited into the core during accretion, which is then reradiated as neutrinos, and infer the core temperature. For a nucleonic core, this requires that the nucleons are unpaired and that the proton fraction exceeds a critical value to allow the direct Urca reaction to proceed. The neutron star in MXB 1659-29 is the first with a firmly detected thermal component in its x-ray spectrum that needs a fast neutrino-cooling process. Measurements of the temperature variation of the neutron star core during quiescence would place an upper limit on the core specific heat and serve as a check on the fraction of the neutron star core in which nucleons are unpaired.

Analysis of lead free tin-silver-copper and tin-lead solder wetting reactions

NASA Astrophysics Data System (ADS)

Anson, Scott J.

Lead free electronics soldering is driven by a combination of health and environmental concerns, international legislation and marketing pressure by lead free electronics manufacturing competitors. Since July 1, 2006, companies that do not comply with the European Union legislation are not able to sell circuit assemblies with lead solder in the European Union. China has developed its own regulations, based on the European Union documents with a compliance date of March 1, 2007. Extensive testing by the electronics community has determined that the Sn - Ag - Cu (SAC) family of alloys is the preferred choice for lead free Surface Mount Technology (SMT) soldering. The 96.5Sn/3.0Ag/0.5Cu alloy was used in this study. Lead free soldering requires an increase in reflow peak temperatures which further aggravates component moisture sensitivity risks and thereby decreases assembly yield. Prior research has revealed an enhanced solder spreading phenomena at lower peak temperature and shorter time above liquidus with 63Sn/37Pb solder. This current research investigated solder wetting reactions in 63Sn/37Pb and 96.5Sn/3.0Ag/0.5Cu (SAC305) using materials and manufacturing systems that are industry relevant. The objective was to advance the knowledge base of metal wetting while developing a reflow assembly process that minimized the component defect rates. The components are damaged during reflow by popcorn delamination, which is the result of moisture absorption and subsequent rapid evaporation. A classical Design Of Experiments (DOE) approach was used, with wetted area as the response variable. Outside of the DOE, substrate dissolution depth, and substrate surface new phase formation (reaction product) distance from the triple line (solder wetting front) and reaction product thickness in the solder joint (under the solder) were also analyzed. The samples were analyzed for correlation of reflow peak temperature, reflow Time Above Liquidus (TAL), wetted area, reaction product distance from the triple line, substrate dissolution depth, triple line ridge (substrate protrusion into the molten solder) formation and reaction product thickness in the solder joint. The general results are (1) an improved understanding of 63Sn/37Pb and 96.5Sn/3.0Ag/0.5Cu WT% solder wetting reactions, (2) reduced 63Sn/37Pb and SAC reflow peak temperatures, and thereby reduced risk of moisture sensitivity damage to components. The significance of these results are (1) enhanced applied understanding of the complexity of molten metal wetting a substrate and (2) enhanced assembly yield due to minimal aggravation of component moisture sensitivity. The uniqueness of this research is that it utilized a holistic Systems Science approach which provided a combined microscopic (substrate and molten metal reactions) and macroscopic (wetted area) analysis of metal wetting using materials and processes that were directly relevant to electronics manufacturing.

Chemical reaction mechanisms in solution from brute force computational Arrhenius plots.

PubMed

Kazemi, Masoud; Åqvist, Johan

2015-06-01

Decomposition of activation free energies of chemical reactions, into enthalpic and entropic components, can provide invaluable signatures of mechanistic pathways both in solution and in enzymes. Owing to the large number of degrees of freedom involved in such condensed-phase reactions, the extensive configurational sampling needed for reliable entropy estimates is still beyond the scope of quantum chemical calculations. Here we show, for the hydrolytic deamination of cytidine and dihydrocytidine in water, how direct computer simulations of the temperature dependence of free energy profiles can be used to extract very accurate thermodynamic activation parameters. The simulations are based on empirical valence bond models, and we demonstrate that the energetics obtained is insensitive to whether these are calibrated by quantum mechanical calculations or experimental data. The thermodynamic activation parameters are in remarkable agreement with experiment results and allow discrimination among alternative mechanisms, as well as rationalization of their different activation enthalpies and entropies.

Chemical reaction mechanisms in solution from brute force computational Arrhenius plots

PubMed Central

Kazemi, Masoud; Åqvist, Johan

2015-01-01

Decomposition of activation free energies of chemical reactions, into enthalpic and entropic components, can provide invaluable signatures of mechanistic pathways both in solution and in enzymes. Owing to the large number of degrees of freedom involved in such condensed-phase reactions, the extensive configurational sampling needed for reliable entropy estimates is still beyond the scope of quantum chemical calculations. Here we show, for the hydrolytic deamination of cytidine and dihydrocytidine in water, how direct computer simulations of the temperature dependence of free energy profiles can be used to extract very accurate thermodynamic activation parameters. The simulations are based on empirical valence bond models, and we demonstrate that the energetics obtained is insensitive to whether these are calibrated by quantum mechanical calculations or experimental data. The thermodynamic activation parameters are in remarkable agreement with experiment results and allow discrimination among alternative mechanisms, as well as rationalization of their different activation enthalpies and entropies. PMID:26028237

A practical and catalyst-free trifluoroethylation reaction of amines using trifluoroacetic acid

NASA Astrophysics Data System (ADS)

Andrews, Keith G.; Faizova, Radmila; Denton, Ross M.

2017-06-01

Amines are a fundamentally important class of biologically active compounds and the ability to manipulate their physicochemical properties through the introduction of fluorine is of paramount importance in medicinal chemistry. Current synthesis methods for the construction of fluorinated amines rely on air and moisture sensitive reagents that require special handling or harsh reductants that limit functionality. Here we report practical, catalyst-free, reductive trifluoroethylation reactions of free amines exhibiting remarkable functional group tolerance. The reactions proceed in conventional glassware without rigorous exclusion of either moisture or oxygen, and use trifluoroacetic acid as a stable and inexpensive fluorine source. The new methods provide access to a wide range of medicinally relevant functionalized tertiary β-fluoroalkylamine cores, either through direct trifluoroethylation of secondary amines or via a three-component coupling of primary amines, aldehydes and trifluoroacetic acid. A reduction of in situ-generated silyl ester species is proposed to account for the reductive selectivity observed.

Peripheral elastic and inelastic scattering of 17,18O on light targets at 12 MeV/nucleon

NASA Astrophysics Data System (ADS)

Carstoiu, F.; Al-Abdullah, T.; Gagliardi, C. A.; Trache, L.

2015-02-01

The elastic and inelastic scattering of 17,18O with light targets has been undertaken at 12 MeV/nucleon in order to determine the optical potentials needed for the transfer reaction 13C (17O ,18O )12C . Optical potentials in both incoming and outgoing channels have been determined in a single experiment. This transfer reaction was used to infer the direct capture rate to the 17F ( p ,γ)18Ne which is essential to estimate the production of 18F at stellar energies in ONe novae. We demonstrate the stability of the ANC method and OMP results using good quality elastic and inelastic scattering data with stable beams. The peripherality of our reaction is inferred from a semiclassical decomposition of the total scattering amplitude into barrier and internal barrier components. Comparison between elastic scattering of 17O , 18O and 16O projectiles is made.

Hydrothermal liquefaction of Gracilaria gracilis and Cladophora glomerata macro-algae for biocrude production.

PubMed

Parsa, Mehran; Jalilzadeh, Hamoon; Pazoki, Maryam; Ghasemzadeh, Reza; Abduli, MohammadAli

2018-02-01

The potential of Gracilaria gracilis (G. gracilis) and Cladophora glomerata (C. glomerata) macro-algae species harvested from Caspian Sea for biocrude oil production under Hydrothermal Liquefaction (HTL) reaction at 350 °C and 15 min has been investigated. Furthermore, the effect of using recycled aqueous phase as the HTL reaction solvent was studied. The biocrude yield for G. gracilis and C. glomerata was 15.7 and 16.9 wt%, respectively with higher heating value (HHV) of 36.01 and 33.06 MJ/kg. The sources of each existing component in bio-oil were identified by GC-MS based on their suggested reaction pathways. Moreover, after two series of aqueous solution recycling, experiments showed that the bio-oil yield significantly increased compared with the initial condition. This increasing directly relates with recovery of carbon content from the aqueous solution residue. Copyright © 2017. Published by Elsevier Ltd.

Tenebrio beetles use magnetic inclination compass

NASA Astrophysics Data System (ADS)

Vácha, Martin; Drštková, Dana; Půžová, Tereza

2008-08-01

Animals that guide directions of their locomotion or their migration routes by the lines of the geomagnetic field use either polarity or inclination compasses to determine the field polarity (the north or south direction). Distinguishing the two compass types is a guideline for estimation of the molecular principle of reception and has been achieved for a number of animal groups, with the exception of insects. A standard diagnostic method to distinguish a compass type is based on reversing the vertical component of the geomagnetic field, which leads to the opposite reactions of animals with two different compass types. In the present study, adults of the mealworm beetle Tenebrio molitor were tested by means of a two-step laboratory test of magnetoreception. Beetles that were initially trained to memorize the magnetic position of the light source preferred, during the subsequent test, this same direction, pursuant geomagnetic cues only. In the following step, the vertical component was reversed between the training and the test. The beetles significantly turned their preferred direction by 180°. Our results brought until then unknown original findings that insects, represented here by the T. molitor species, use—in contrast to another previously researched Arthropod, spiny lobster—the inclination compass.

Acute kidney injury complicating bee stings – a review

PubMed Central

da Silva, Geraldo Bezerra; Vasconcelos, Adolfo Gomes; Rocha, Amanda Maria Timbó; de Vasconcelos, Vanessa Ribeiro; de Barros, João; Fujishima, Julye Sampaio; Ferreira, Nathália Barros; Barros, Elvino José Guardão; Daher, Elizabeth De Francesco

2017-01-01

ABSTRACT Bee stings can cause severe reactions and have caused many victims in the last years. Allergic reactions can be triggered by a single sting and the greater the number of stings, the worse the prognosis. The poisoning effects can be systemic and can eventually cause death. The poison components are melitin, apamin, peptide 401, phospholipase A2, hyaluronidase, histamine, dopamine, and norepinephrine, with melitin being the main lethal component. Acute kidney injury (AKI) can be observed in patients suffering from bee stings and this is due to multiple factors, such as intravascular hemolysis, rhabdomyolysis, hypotension and direct toxicity of the venom components to the renal tubules. Arterial hypotension plays an important role in this type of AKI, leading to ischemic renal lesion. The most commonly identified biopsy finding in these cases is acute tubular necrosis, which can occur due to both, ischemic injury and the nephrotoxicity of venom components. Hemolysis and rhabdomyolysis reported in many cases in the literature, were demonstrated by elevated serum levels of indirect bilirubin and creatine kinase. The severity of AKI seems to be associated with the number of stings, since creatinine levels were higher, in most cases, when there were more than 1,000 stings. The aim of this study is to present an updated review of AKI associated with bee stings, including the currently advised clinical approach. PMID:28591253

Determining the 13C(α, n)16O absolute cross section through the concurrent application of ANC and THM and astrophysical consequences for the s-process in AGB-LMSs.

NASA Astrophysics Data System (ADS)

Trippella, Oscar; La Cognata, Marco

2018-01-01

The 13C(α, n)16O reaction is considered to be the most important neutron source for the s-process main component in low-mass asymptotic giant branch stars. No direct experimental data exist at very low energies and measurements performed through direct techniques show inconsistent results, mostly in their absolute values. In this context, we reversed the usual normalization procedure combining two indirect approaches, the asymptotic normalization coefficient and the Trojan Horse Method, to unambiguously determine the absolute value of the 13C(α, n)16O astrophysical S(E)-factor in the most relevant energy-region for astrophysics. Adopting the new reaction rate for the n-source in the NEWTON s-process nucleosynthesis code, astrophysical calculations show only limited variations, less than 1%, for those nuclei whose production is considered to be totally due to slow neutron captures.

Substrate-Directed Catalytic Selective Chemical Reactions.

PubMed

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.

Molecular analysis of a mutant defective in photosynthetic oxygen evolution and isolation of a complementing clone by a novel screening procedure.

PubMed Central

Dzelzkalns, V A; Bogorad, L

1988-01-01

Photosynthesis-defective mutants of the transformable cyanobacterium Synechocystis 6803 have been isolated following nitrosoguanidine mutagenesis. The photosystem II- phenotype of one of these mutants is shown by DNA sequencing to be attributable to a short deletion in psbC, the gene encoding the 44-kd, chlorophyll-binding protein of photosystem II. Although not a component of the reaction center of photosystem II, the 44-kd protein is none the less shown to be essential in vivo for photosystem II activity. The deletion in psbC also results in greatly diminished levels of D-2 (a component of the reaction center of photosystem II) indicating that the loss of the product of the psbC gene affects the assembly or stability of the photosystem II reaction center. The isolation of a clone capable of restoring both photosystem II activity and photoautotrophy to the mutant cells was aided by the observation that restriction fragments or cloned Synechocystis 6803 DNA applied in liquid or in melted agarose directly onto a lawn of Synechocystis 6803 will lead to the transformation of the cells. This in situ 'dot' transformation procedure provides a convenient method for the rapid identification of fractions or clones containing complementing Synechocystis 6803 DNA. Images PMID:3130247

Local reaction kinetics by imaging☆

PubMed Central

Suchorski, Yuri; Rupprechter, Günther

2016-01-01

In the present contribution we present an overview of our recent studies using the “kinetics by imaging” approach for CO oxidation on heterogeneous model systems. The method is based on the correlation of the PEEM image intensity with catalytic activity: scaled down to the μm-sized surface regions, such correlation allows simultaneous local kinetic measurements on differently oriented individual domains of a polycrystalline metal-foil, including the construction of local kinetic phase diagrams. This allows spatially- and component-resolved kinetic studies and, e.g., a direct comparison of inherent catalytic properties of Pt(hkl)- and Pd(hkl)-domains or supported μm-sized Pd-powder agglomerates, studies of the local catalytic ignition and the role of defects and grain boundaries in the local reaction kinetics. PMID:26865736

Bio oil synthesis by coupling biological biomass pretreatment and catalytic hydroliquefaction process.

PubMed

Hamieh, S; Beauchet, R; Lemee, L; Toufaily, J; Koubaissy, B; Hamieh, T; Pouilloux, Y; Pinard, L

2014-03-01

The bio-oil synthesis from a mixture of wastes (7wt.% straw, 38wt.% wood, and 45wt.% grass) was carried out by direct liquefaction reaction using Raney Nickel as catalyst and tetralin as solvent. The green wastes were biologically degraded during 3 months. Longer the destructuration time; higher the yield into oil is. Biological pretreatment of green wastes promotes the liquefaction process. Among the components of degraded biomass, Humin, the major fraction (60-80wt.%) that was favored by the biological treatment, yields to a bio oil extremely energetic with a HHV close to biopetroleum (40MJ kg(-1)), contrariwise, Fulvic acids (2-12wt.%), the minor fraction is refractory to liquefaction reaction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hypothesis for thermal activation of the caspase cascade in apoptotic cell death at elevated temperatures

NASA Astrophysics Data System (ADS)

Pearce, John A.

2013-02-01

Apoptosis is an especially important process affecting disease states from HIV-AIDS to auto-immune disease to cancer. A cascade of initiator and executioner capsase functional proteins is the hallmark of apoptosis. When activated the various caspases activate other caspases or cleave structural proteins of the cytoskeleton, resulting in "blebbing" of the plasma membrane forming apoptotic bodies that completely enclose the disassembled cellular components. Containment of the cytosolic components within the apoptotic bodies differentiates apoptosis from necroptosis and necrosis, both of which release fragmented cytosol and other cellular constituents into the intracellular space. Biochemical models of caspase activation reveal the extensive feedback loops characteristic of apoptosis. They clearly explain the failure of Arrhenius models to give accurate predictions of cell survival curves in hyperthermic heating protocols. Nevertheless, each of the individual reaction velocities can reasonably be assumed to follow Arrhenius kinetics. If so, the thermal sensitivity of the reaction velocity to temperature elevation is: ∂k/∂T = Ea [k/RT2]. Particular reaction steps described by higher activation energies, Ea, are likely more thermally-sensitive than lower energy reactions and may initiate apoptosis in the absence of other stress signals. Additionally, while the classical irreversible Arrhenius formulation fails to accurately represent many cell survival and/or dye uptake curves - those that display an early stage shoulder region - an expanded reversible model of the law of mass action equation seems to prove effective and is directly based on a firm theoretical thermodynamic foundation.

Consensus document on the approach to children with allergic reactions after vaccination or allergy to vaccine components.

PubMed

Echeverría-Zudaire, Luis A; Ortigosa-del Castillo, Luis; Alonso-Lebrero, Elena; Álvarez-García, Francisco J; Cortés-Álvarez, Nuria; García-Sánchez, Nuria; Martorell-Aragonés, Antonio

2015-01-01

Vaccinations are one of the main public health tools for the control of vaccine-preventable diseases. If a child is identified as having had an allergic reaction to a vaccine, subsequent immunisations will probably be suspended - with the risks such a decision implies. The incidence of severe allergic reactions is very low, ranging between 0.5 and 1 cases/100,000 doses. Rather than the vaccine antigens as such, the causes of allergic reactions to vaccines are often residual protein components of the manufacturing process such as gelatine or egg, and less commonly yeasts or latex. Most vaccine reactions are mild and circumscribed to the injection site; although in some cases severe anaphylactic reactions can be observed. If an immediate-type allergic reaction is suspected at vaccination, or if a child with allergy to some of the vaccine components is scheduled for vaccination, a correct diagnosis of the possible allergic process must be made. The usual vaccine components must be known in order to determine whether vaccination can be safely performed. Copyright © 2015 SEICAP. Published by Elsevier Espana. All rights reserved.

Three-Component Reaction Discovery Enabled by Mass Spectrometry of Self-Assembled Monolayers

PubMed Central

Montavon, Timothy J.; Li, Jing; Cabrera-Pardo, Jaime R.; Mrksich, Milan; Kozmin, Sergey A.

2011-01-01

Multi-component reactions have been extensively employed in many areas of organic chemistry. Despite significant progress, the discovery of such enabling transformations remains challenging. Here, we present the development of a parallel, label-free reaction-discovery platform, which can be used for identification of new multi-component transformations. Our approach is based on the parallel mass spectrometric screening of interfacial chemical reactions on arrays of self-assembled monolayers. This strategy enabled the identification of a simple organic phosphine that can catalyze a previously unknown condensation of siloxy alkynes, aldehydes and amines to produce 3-hydroxy amides with high efficiency and diastereoselectivity. The reaction was further optimized using solution phase methods. PMID:22169871

Early reaction kinetics of contemporary glass-ionomer restorative materials.

PubMed

Roberts, Howard W; Berzins, David W

2015-02-01

To investigate polyalkenoate reaction rates in conventional glass-ionomer cement (GIC) and resin-modified glass ionomer (RMGI) restorative materials using infrared spectroscopy. Nine conventional GIC and six RMGI restorative materials were prepared according to manufacturer's directions and placed on a FTIR (Fourier transform infrared spectroscopy) diamond ATR (attenuated total reflectance) surface. FTIR spectra (700 to 1800 cm-1) were obtained each minute for 3 h. VLC specimens were light polymerized after 1 min; at 5 min, all samples were covered with gauze saturated with deionized water. Polyalkenoate reaction was determined by measuring area growth (Å/cm-1) between 1375 and 1500 cm-1. Mean peak areas were determined at 5, 15, 30, 90, and 180 min and compared using ANOVA (p = 0.05) RESULTS: For all RMGI materials, VLC polymerization inhibited the polyalkenoate reaction rate. Compared to conventional GIC, RMGI materials demonstrated less polyalkenoate reaction. Compared to dark curing, RMGI light polymerization significantly inhibited the polyalkenoate reaction rate. The addition of resin components to glass-ionomer products significantly retards and impedes the polyalkenoate reaction. The polyalkenoate reaction rate of RMGI products was significantly lower than that of self-curing GIC restorative materials. Furthermore, light activation of RMGI products further retards the polyalkenoate rate. When clinicians require the therapeutic benefit of a polyalkenoate product, perhaps a conventional GIC restorative product should be the first material of choice.

Reaction dynamics analysis of a reconstituted Escherichia coli protein translation system by computational modeling

PubMed Central

Matsuura, Tomoaki; Tanimura, Naoki; Hosoda, Kazufumi; Yomo, Tetsuya; Shimizu, Yoshihiro

2017-01-01

To elucidate the dynamic features of a biologically relevant large-scale reaction network, we constructed a computational model of minimal protein synthesis consisting of 241 components and 968 reactions that synthesize the Met-Gly-Gly (MGG) peptide based on an Escherichia coli-based reconstituted in vitro protein synthesis system. We performed a simulation using parameters collected primarily from the literature and found that the rate of MGG peptide synthesis becomes nearly constant in minutes, thus achieving a steady state similar to experimental observations. In addition, concentration changes to 70% of the components, including intermediates, reached a plateau in a few minutes. However, the concentration change of each component exhibits several temporal plateaus, or a quasi-stationary state (QSS), before reaching the final plateau. To understand these complex dynamics, we focused on whether the components reached a QSS, mapped the arrangement of components in a QSS in the entire reaction network structure, and investigated time-dependent changes. We found that components in a QSS form clusters that grow over time but not in a linear fashion, and that this process involves the collapse and regrowth of clusters before the formation of a final large single cluster. These observations might commonly occur in other large-scale biological reaction networks. This developed analysis might be useful for understanding large-scale biological reactions by visualizing complex dynamics, thereby extracting the characteristics of the reaction network, including phase transitions. PMID:28167777

77 FR 65192 - Agency Forms Undergoing Paperwork Reduction Act Review

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-25

... Component, data on adverse reactions and incidents associated with blood transfusions are used to provide national estimates of adverse reactions and incidents. The Long-Term Care Facility (LTCF) Component is used.... Laboratory Technologist. 57.304: Hemovigilance Adverse Reaction Medical/Clinical 500 120 10/60 Laboratory...

Catalytic distillation structure

DOEpatents

Smith, Jr., Lawrence A.

1984-01-01

Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

Impact of Temperature and Non-Gaussian Statistics on Electron Transfer in Donor-Bridge-Acceptor Molecules.

PubMed

Waskasi, Morteza M; Newton, Marshall D; Matyushov, Dmitry V

2017-03-30

A combination of experimental data and theoretical analysis provides evidence of a bell-shaped kinetics of electron transfer in the Arrhenius coordinates ln k vs 1/T. This kinetic law is a temperature analogue of the familiar Marcus bell-shaped dependence based on ln k vs the reaction free energy. These results were obtained for reactions of intramolecular charge shift between the donor and acceptor separated by a rigid spacer studied experimentally by Miller and co-workers. The non-Arrhenius kinetic law is a direct consequence of the solvent reorganization energy and reaction driving force changing approximately as hyperbolic functions with temperature. The reorganization energy decreases and the driving force increases when temperature is increased. The point of equality between them marks the maximum of the activationless reaction rate. Reaching the consistency between the kinetic and thermodynamic experimental data requires the non-Gaussian statistics of the donor-acceptor energy gap described by the Q-model of electron transfer. The theoretical formalism combines the vibrational envelope of quantum vibronic transitions with the Q-model describing the classical component of the Franck-Condon factor and a microscopic solvation model of the solvent reorganization energy and the reaction free energy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Waskasi, Morteza M.; Newton, Marshall D.; Matyushov, Dmitry V.

A combination of experimental data and theoretical analysis provides evidence of a bell-shaped kinetics of electron transfer in the Arrhenius coordinates ln k vs 1/T . This kinetic law is a temperature analog of the familiar Marcus bell-shaped dependence based on ln k vs the reaction free energy. These results were obtained for reactions of intramolecular charge shift between the donor and acceptor separated by a rigid spacer studied experimentally by Miller and co-workers. The non-Arrhenius kinetic law is a direct consequence of the solvent reorganization energy and reaction driving force changing approximately as hyperbolic functions with temperature. The reorganizationmore » energy decreases and the driving force increases when temperature is increased. The point of equality between them marks the maximum of the activationless reaction rate. Reaching the consistency between the kinetic and thermodynamic experimental data requires the non-Gaussian statistics of the donor-acceptor energy gap described by the Q-model of electron transfer. Furthermore, the theoretical formalism combines the vibrational envelope of quantum vibronic transitions with the Q-model describing the classical component of the Franck-Condon factor and a microscopic solvation model of the solvent reorganization energy and the reaction free energy.« less

Probabilistic maturation reaction norms assessed from mark–recaptures of wild fish in their natural habitat

PubMed Central

Olsen, Esben M; Serbezov, Dimitar; Vøllestad, Leif A

2014-01-01

Reaction norms are a valuable tool in evolutionary biology. Lately, the probabilistic maturation reaction norm approach, describing probabilities of maturing at combinations of age and body size, has been much applied for testing whether phenotypic changes in exploited populations of fish are mainly plastic or involving an evolutionary component. However, due to typical field data limitations, with imperfect knowledge about individual life histories, this demographic method still needs to be assessed. Using 13 years of direct mark–recapture observations on individual growth and maturation in an intensively sampled population of brown trout (Salmo trutta), we show that the probabilistic maturation reaction norm approach may perform well even if the assumption of equal survival of juvenile and maturing fish does not hold. Earlier studies have pointed out that growth effects may confound the interpretation of shifts in maturation reaction norms, because this method in its basic form deals with body size rather than growth. In our case, however, we found that juvenile body size, rather than annual growth, was more strongly associated with maturation. Viewed against earlier studies, our results also underscore the challenges of generalizing life-history patterns among species and populations. PMID:24967078

Experimental estimation of energy absorption during heel strike in human barefoot walking.

PubMed

Baines, Patricia M; Schwab, A L; van Soest, A J

2018-01-01

Metabolic energy expenditure during human gait is poorly understood. Mechanical energy loss during heel strike contributes to this energy expenditure. Previous work has estimated the energy absorption during heel strike as 0.8 J using an effective foot mass model. The aim of our study is to investigate the possibility of determining the energy absorption by more directly estimating the work done by the ground reaction force, the force-integral method. Concurrently another aim is to compare this method of direct determination of work to the method of an effective foot mass model. Participants of our experimental study were asked to walk barefoot at preferred speed. Ground reaction force and lower leg kinematics were collected at high sampling frequency (3000 Hz; 1295 Hz), with tight synchronization. The work done by the ground reaction force is 3.8 J, estimated by integrating this force over the foot-ankle deformation. The effective mass model is improved by dropping the assumption that foot-ankle deformation is maximal at the instant of the impact force peak. On theoretical grounds it is clear that in the presence of substantial damping that peak force and peak deformation do not occur simultaneously. The energy absorption results, due the vertical force only, corresponding to the force-integral method is similar to the results of the improved application of the effective mass model (2.7 J; 2.5 J). However the total work done by the ground reaction force calculated by the force-integral method is significantly higher than that of the vertical component alone. We conclude that direct estimation of the work done by the ground reaction force is possible and preferable over the use of the effective foot mass model. Assuming that energy absorbed is lost, the mechanical energy loss of heel strike is around 3.8 J for preferred walking speeds (≈ 1.3 m/s), which contributes to about 15-20% of the overall metabolic cost of transport.

Simulations of photochemical smog formation in complex urban areas

NASA Astrophysics Data System (ADS)

Muilwijk, C.; Schrijvers, P. J. C.; Wuerz, S.; Kenjereš, S.

2016-12-01

In the present study we numerically investigated the dispersion of photochemical reactive pollutants in complex urban areas by applying an integrated Computational Fluid Dynamics (CFD) and Computational Reaction Dynamics (CRD) approach. To model chemical reactions involved in smog generation, the Generic Reaction Set (GRS) approach is used. The GRS model was selected since it does not require detailed modeling of a large set of reactive components. Smog formation is modeled first in the case of an intensive traffic emission, subjected to low to moderate wind conditions in an idealized two-dimensional street canyon with a building aspect ratio (height/width) of one. It is found that Reactive Organic Components (ROC) play an important role in the chemistry of smog formation. In contrast to the NOx/O3 photochemical steady state model that predicts a depletion of the (ground level) ozone, the GRS model predicts generation of ozone. Secondly, the effect of direct sunlight and shadow within the street canyon on the chemical reaction dynamics is investigated for three characteristic solar angles (morning, midday and afternoon). Large differences of up to one order of magnitude are found in the ozone production for different solar angles. As a proof of concept for real urban areas, the integrated CFD/CRD approach is applied for a real scale (1 × 1 km2) complex urban area (a district of the city of Rotterdam, The Netherlands) with high traffic emissions. The predicted pollutant concentration levels give realistic values that correspond to moderate to heavy smog. It is concluded that the integrated CFD/CRD method with the GRS model of chemical reactions is both accurate and numerically robust, and can be used for modeling of smog formation in complex urban areas.

Vaccination in children with allergy to non active vaccine components.

PubMed

Franceschini, Fabrizio; Bottau, Paolo; Caimmi, Silvia; Crisafulli, Giuseppe; Lucia, Liotti; Peroni, Diego; Saretta, Francesca; Vernich, Mario; Povesi Dascola, Carlotta; Caffarelli, Carlo

2015-01-01

Childhood immunisation is one of the greatest public health successes of the last century. Vaccines contain an active component (the antigen) which induces the immune response. They may also contain additional components such as preservatives, additives, adjuvants and traces of other substances. This review provides information about risks of hypersensitivity reactions to components of vaccines. Furthermore, recommendations to avoid or reduce reactions to vaccine components have been detailed.

BioMog: A Computational Framework for the De Novo Generation or Modification of Essential Biomass Components

PubMed Central

Tervo, Christopher J.; Reed, Jennifer L.

2013-01-01

The success of genome-scale metabolic modeling is contingent on a model's ability to accurately predict growth and metabolic behaviors. To date, little focus has been directed towards developing systematic methods of proposing, modifying and interrogating an organism's biomass requirements that are used in constraint-based models. To address this gap, the biomass modification and generation (BioMog) framework was created and used to generate lists of biomass components de novo, as well as to modify predefined biomass component lists, for models of Escherichia coli (iJO1366) and of Shewanella oneidensis (iSO783) from high-throughput growth phenotype and fitness datasets. BioMog's de novo biomass component lists included, either implicitly or explicitly, up to seventy percent of the components included in the predefined biomass equations, and the resulting de novo biomass equations outperformed the predefined biomass equations at qualitatively predicting mutant growth phenotypes by up to five percent. Additionally, the BioMog procedure can quantify how many experiments support or refute a particular metabolite's essentiality to a cell, and it facilitates the determination of inconsistent experiments and inaccurate reaction and/or gene to reaction associations. To further interrogate metabolite essentiality, the BioMog framework includes an experiment generation algorithm that allows for the design of experiments to test whether a metabolite is essential. Using BioMog, we correct experimental results relating to the essentiality of thyA gene in E. coli, as well as perform knockout experiments supporting the essentiality of protoheme. With these capabilities, BioMog can be a valuable resource for analyzing growth phenotyping data and component of a model developer's toolbox. PMID:24339916

The Reaction between Nitric Oxide, Glutathione and Oxygen in the Presence and Absence of Protein: How are S-Nitrosothiols Formed?

PubMed Central

Keszler, Agnes; Zhang, Yanhong; Hogg, Neil

2009-01-01

The reaction between NO, thiols and oxygen has been studied in some detail in vitro due to its perceived importance in the mechanism of NO-dependent signal transduction. The formation of S-nitrosothiols and thiol disulfides from this chemistry has been suggested to be an important component of the biological chemistry of NO, and such subsequent thiol modifications may result in changes in cellular function and phenotype. In this study we have re-investigated this reaction using both experiment and simulation and conclude that: (i) S-Nitrosation through radical and non-radical pathways is occurring simultaneously (ii) S-Nitrosation through direct addition of NO to thiol does not occur to any meaningful extent and (iii) protein hydrophobic environments do not catalyze or enhance S-nitrosation of either themselves or of glutathione. We conclude that S-nitrosation and disulfide formation in this system occur only after the initial reaction between NO and oxygen to form nitrogen dioxide, and that hydrophobic protein environments are unlikely to play any role in enhancing and targeting S-nitrosothiol formation. PMID:19819329

X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study

NASA Astrophysics Data System (ADS)

Inkinen, Juho; Niskanen, Johannes; Talka, Tuomas; Sahle, Christoph J.; Müller, Harald; Khriachtchev, Leonid; Hashemi, Javad; Akbari, Ali; Hakala, Mikko; Huotari, Simo

2015-11-01

A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study

PubMed Central

Inkinen, Juho; Niskanen, Johannes; Talka, Tuomas; Sahle, Christoph J.; Müller, Harald; Khriachtchev, Leonid; Hashemi, Javad; Akbari, Ali; Hakala, Mikko; Huotari, Simo

2015-01-01

A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering. PMID:26568420

Subatomic-scale force vector mapping above a Ge(001) dimer using bimodal atomic force microscopy

NASA Astrophysics Data System (ADS)

Naitoh, Yoshitaka; Turanský, Robert; Brndiar, Ján; Li, Yan Jun; Štich, Ivan; Sugawara, Yasuhiro

2017-07-01

Probing physical quantities on the nanoscale that have directionality, such as magnetic moments, electric dipoles, or the force response of a surface, is essential for characterizing functionalized materials for nanotechnological device applications. Currently, such physical quantities are usually experimentally obtained as scalars. To investigate the physical properties of a surface on the nanoscale in depth, these properties must be measured as vectors. Here we demonstrate a three-force-component detection method, based on multi-frequency atomic force microscopy on the subatomic scale and apply it to a Ge(001)-c(4 × 2) surface. We probed the surface-normal and surface-parallel force components above the surface and their direction-dependent anisotropy and expressed them as a three-dimensional force vector distribution. Access to the atomic-scale force distribution on the surface will enable better understanding of nanoscale surface morphologies, chemical composition and reactions, probing nanostructures via atomic or molecular manipulation, and provide insights into the behaviour of nano-machines on substrates.

Collective Dynamics of Periplasmic Glutamine Binding Protein upon Domain Closure

PubMed Central

Loeffler, Hannes H.; Kitao, Akio

2009-01-01

The glutamine binding protein is a vital component of the associated ATP binding cassette transport systems responsible for the uptake of glutamine into the cell. We have investigated the global movements of this protein by molecular dynamics simulations and principal component analysis (PCA). We confirm that the most dominant mode corresponds to the biological function of the protein, i.e., a hinge-type motion upon ligand binding. The closure itself was directly observed from two independent trajectories whereby PCA was used to elucidate the nature of this closing reaction. Two intermediary states are identified and described in detail. The ligand binding induces the structural change of the hinge regions from a discontinuous β-sheet to a continuous one, which also enhances softness of the hinge and modifies the direction of hinge motion to enable closing. We also investigated the convergence behavior of PCA modes, which were found to converge rather quickly when the associated magnitudes of the eigenvalues are well separated. PMID:19883597

Low molecular weight hyaluronic acid effects on murine macrophage nitric oxide production.

PubMed

Lyle, Daniel B; Breger, Joyce C; Baeva, Larissa F; Shallcross, Jonathan C; Durfor, Charles N; Wang, Nam Sun; Langone, John J

2010-09-01

Hyaluronic acid (HA) is increasingly used for a number of medical device applications. Since the chemical structure of HA is identical no matter its bacterial or animal origin, it should be the ideal biomaterial. However, short term transient inflammatory reactions are common, while rare long-term adverse events may correlate with subclinical chronic inflammation. Concern has been raised that low molecular weight components or degradation fragments from implanted HA may directly stimulate inflammatory reactions. This study examined a panel of HA molecular weights from the unitary disaccharide up to 1.7 x 10(6) Dalton lengths, in which endotoxin was assayed at a very low level (less than 0.03 EU/mg). The murine cell line RAW 264.7, rat splenocytes, and rat adherent differentiated primary macrophages were assayed for nitric oxide production under a variety of inflammatory conditions plus or minus HA. Under the highest inflammatory states, nitric oxide production was mildly suppressed by HMW-HA while slightly augmented by LMW-HA at mg/mL concentrations. However, at micromolar concentrations fragments below 5000 Daltons, thought to have drug-like qualities, were without effect. These data support the hypothesis that if endotoxin is reduced to an extremely low level, LMW-HA may not directly provoke normal tissue macrophage-mediated inflammatory reactions. (c) 2010 Wiley Periodicals, Inc.

Photo-Fenton-assisted ozonation of p-Coumaric acid in aqueous solution.

PubMed

Monteagudo, J M; Carmona, M; Durán, A

2005-08-01

The degradation of p-Coumaric acid present in olive oil mill wastewater was investigated as a pretreatment stage to obtain more easily biodegradable molecules, with lower toxicity that facilitates subsequent anaerobic digestion. Thus, photo-Fenton-assisted ozonation has been studied and compared with ozonation at alkaline pH and conventional single ultraviolet (UV) and acid ozonation treatments. In the combined process, the overall kinetic rate constant was split into various components: direct oxidation by UV light, direct oxidation by ozone and oxidation by hydroxyl radicals. Molecular and/or radical ozone reaction was studied by conducting the reaction in the presence and absence of tert-butylalcohol at pHs 2, 7 and 9. Ozone oxidation rate increases with pH or by the addition of Fenton reagent and/or UV radiation due to generation of hydroxyl radicals, *OH. Hydrogen peroxide and ferrous ion play a double role during oxidation since at low concentrations they act as initiators of hydroxyl radicals but at high concentrations they act as radical scavengers. Finally, the additional levels of degradation by formation of hydroxyl radicals have been quantified in comparison to the conventional single processes and an equation is proposed for the reaction rate as a function of studied operating variables.

The interaction of reaction-bonded silicon carbide and inconel 600 with a nickel-based brazing alloy

NASA Astrophysics Data System (ADS)

McDermid, J. R.; Pugh, M. D.; Drew, R. A. L.

1989-09-01

The objective of the present research was to join reaction-bonded silicon carbide (RBSC) to INCONEL 600 (a nickel-based superalloy) for use in advanced heat engine applications using either direct brazing or composite interlayer joining. Direct brazing experiments employed American Welding Society (AWS) BNi-5, a commercial nickel-based brazing alloy, as a filler material; composite interlayers consisted of intimate mixtures of α-SiC and BNi-5 powders. Both methods resulted in the liquid filler metal forming a Ni-Si liquid with the free Si in the RBSC, which, in turn, reacted vigorously with the SiC component of the RBSC to form low melting point constituents in both starting materials and Cr carbides at the metal-ceramic interface. Using solution thermodynamics, it was shown that a Ni-Si liquid of greater than 60 at. pct Ni will decompose a-SiC at the experimental brazing temperature of 1200 ‡C; these calculations are consistent with the experimentally observed composition profiles and reaction morphology within the ceramic. It was concluded that the joining of RBSC to INCONEL 600 using a nickel-based brazing alloy is not feasible due to the inevitability of the filler metal reacting with the ceramic, degrading the high-temperature properties of the base materials.

Face it or hide it: parental socialization of reappraisal and response suppression

PubMed Central

Gunzenhauser, Catherine; Fäsche, Anika; Friedlmeier, Wolfgang; von Suchodoletz, Antje

2013-01-01

Mastery of cognitive emotion regulation strategies is an important developmental task. This paper focuses on two strategies that occur from preschool age onwards (Stegge and Meerum Terwogt, 2007): reappraisal and response suppression. Parental socialization of these strategies was investigated in a sample of N = 219 parents and their children. Informed by the tripartite model of family impact on children's emotion regulation, direct relations of emotion socialization components (modeling and reactions to the child's negative emotions) and indirect relations of parental emotion-related beliefs (such as parental emotion regulation self-efficacy) were examined. Data on emotion socialization components and parental beliefs on emotion regulation were collected via self-report. Data on children's emotion regulation strategies were collected via parent report. Findings showed direct effects of parental modeling and parenting practices on children's emotion regulation strategies, with distinct socialization paths for reappraisal and response suppression. An indirect effect of parental emotion regulation self-efficacy on children's reappraisal was found. These associations were not moderated by parent sex. Findings highlight the importance of both socialization components and parental emotion-related beliefs for the socialization of cognitive emotion regulation strategies and suggest a domain-specific approach to the socialization of emotion regulation strategies. PMID:24427150

Catalytic distillation structure

DOEpatents

Smith, L.A. Jr.

1984-04-17

Catalytic distillation structure is described for use in reaction distillation columns, and provides reaction sites and distillation structure consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and is present with the catalyst component in an amount such that the catalytic distillation structure consists of at least 10 volume % open space. 10 figs.

Biosynthesis of flat silver nanoflowers: from Flos Magnoliae Officinalis extract to simulation solution

NASA Astrophysics Data System (ADS)

Jing, Xiaolian; Huang, Jiale; Wu, Lingfeng; Sun, Daohua; Li, Qingbiao

2014-03-01

Flat Ag nanoflowers were directly synthesized from the bioreduction of AgNO3 using Flos Magnoliae Officinalis extract without any additional stabilizer or protective agent at room temperature. Effects of concentrations of the Flos Magnoliae Officinalis extract on the Ag nanostructures were investigated. The main components containing flavone, polyphenol, protein, and reducing sugar in the plant extract were thoroughly determined before and after the reaction, and the dialysis experiments were also conducted. The results of components analysis and dialysis showed that gallic acid representing polyphenols played an important role in the biosynthesis of silver nanoplates. Trisodium citrate combined gallic acid solution, instead of Flos Magnoliae Officinalis extract, was employed and successfully simulated the biosynthesis process of the flat Ag nanoflowers.

Cyclotron-based effects on plant gravitropism

NASA Astrophysics Data System (ADS)

Kordyum, E.; Sobol, M.; Kalinina, Ia.; Bogatina, N.; Kondrachuk, A.

Primary roots exhibit positive gravitropism and grow in the direction of the gravitational vector, while shoots respond negatively and grow opposite to the gravitational vector. We first demonstrated that the use of a weak combined magnetic field (CMF), which is comprised of a permanent magnetic field and an alternating magnetic field with the frequency resonance of the cyclotron frequency of calcium ions, can change root gravitropism from a positive direction to negative direction. Two-day-old cress seedlings were gravistimulated in a chamber that was placed into a μ-metal shield where this CMF was created. Using this "new model" of a root gravitropic response, we have studied some of its components including the movement of amyloplasts-statoliths in root cap statocytes and the distribution of Ca 2+ ions in the distal elongation zone during gravistimulation. Unlike results from the control, amyloplasts did not sediment in the distal part of a statocyte, and more Ca 2+ accumulation was observed in the upper side of a gravistimulated root for seedlings treated with the CMF. For plants treated with the CMF, it appears that a root gravitropic reaction occurs by a normal physiological process resulting in root bending although in the opposite direction. These results support the hypothesis that both the amyloplasts in the root cap statocytes and calcium are important signaling components in plant gravitropism.

Simulating the reactions of CO2 in aqueous monoethanolamine solution by reaction ensemble Monte Carlo using the continuous fractional component method.

PubMed

Balaji, Sayee Prasaad; Gangarapu, Satesh; Ramdin, Mahinder; Torres-Knoop, Ariana; Zuilhof, Han; Goetheer, Earl L V; Dubbeldam, David; Vlugt, Thijs J H

2015-06-09

Molecular simulations were used to compute the equilibrium concentrations of the different species in CO2/monoethanolamine solutions for different CO2 loadings. Simulations were performed in the Reaction Ensemble using the continuous fractional component Monte Carlo method at temperatures of 293, 333, and 353 K. The resulting computed equilibrium concentrations are in excellent agreement with experimental data. The effect of different reaction pathways was investigated. For a complete understanding of the equilibrium speciation, it is essential to take all elementary reactions into account because considering only the overall reaction of CO2 with MEA is insufficient. The effects of electrostatics and intermolecular van der Waals interactions were also studied, clearly showing that solvation of reactants and products is essential for the reaction. The Reaction Ensemble Monte Carlo using the continuous fractional component method opens the possibility of investigating the effects of the solvent on CO2 chemisorption by eliminating the need to study different reaction pathways and concentrate only on the thermodynamics of the system.

The Pure Rotational Spectrum of KO

NASA Astrophysics Data System (ADS)

Burton, Mark; Russ, Benjamin; Sheridan, Phillip M.; Bucchino, Matthew; Ziurys, Lucy M.

2017-06-01

The pure rotational spectrum of potassium monoxide (KO) has been recorded using millimeter-wave direct absorption spectroscopy. KO was synthesized by the reaction of potassium vapor, produced in a Broida-type oven, with nitrous oxide. No DC discharge was necessary. Eleven rotational transitions belonging to the ^{2}Π_{3/2} spin-orbit component have been measured and have been fit successfully to a case (c) Hamiltonian. Rotational and lambda-doubling constants for this spin-orbit component have been determined. It has been suggested that the ground electronic state of KO is either ^{2}Π (as for LiO and NaO) or ^{2}Σ (as for RbO and CsO), both of which lie close in energy. Recent computational studies favor a ^{2}Σ ground state. Further measurements of the rotational transitions of the ^{2}Π_{1/2} spin-orbit component and the ^{2}Σ state are currently in progress, as well as the potassium hyperfine structure.

Transient-state kinetic approach to mechanisms of enzymatic catalysis.

PubMed

Fisher, Harvey F

2005-03-01

Transient-state kinetics by its inherent nature can potentially provide more directly observed detailed resolution of discrete events in the mechanistic time courses of enzyme-catalyzed reactions than its more widely used steady-state counterpart. The use of the transient-state approach, however, has been severely limited by the lack of any theoretically sound and applicable basis of interpreting the virtual cornucopia of time and signal-dependent phenomena that it provides. This Account describes the basic kinetic behavior of the transient state, critically examines some currently used analytic methods, discusses the application of a new and more soundly based "resolved component transient-state time-course method" to the L-glutamate-dehydrogenase reaction, and establishes new approaches for the analysis of both single- and multiple-step substituted transient-state kinetic isotope effects.

Direct and indirect photolysis of two quinolinecarboxylic herbicides in aqueous systems.

PubMed

Pinna, Maria Vittoria; Pusino, Alba

2012-02-01

The photodegradation of two quinolinecarboxylic herbicides, 7-chloro-3-methylquinoline-8-carboxylic acid (QMe) and 3,7-dichloroquinoline-8-carboxylic acid (QCl), was studied in aqueous solution at different irradiation wavelengths. The effect of sunlight irradiation was investigated also in the presence of titanium dioxide (TiO(2)). UV irradiation degraded rapidly QMe affording 7-chloro-3-methylquinoline (MeQ) through a decarboxylation reaction. The reaction rate was lower in the presence of dissolved organic carbon (DOC) because of the adsorption of the herbicide on the organic components. Instead, QCl was stable under both UV light and sunlight irradiation. The irradiation of QMe or QCl solutions with simulated sunlight in the presence of TiO(2) produced the complete mineralization of the two herbicides. Copyright © 2011 Elsevier Ltd. All rights reserved.

Catalysis and Multi-Component Reactions

NASA Astrophysics Data System (ADS)

Shibasaki, Masakatsu; Yus, Miguel; Bremner, Stacy; Comer, Eamon; Shore, Gjergji; Morin, Sylvie; Organ, Michael G.; van der Eycken, Erik; Merkul, Eugen; Dorsch, Dieter; Müller, Thomas J. J.; Ryabukhin, Sergey V.; Ostapchuk, Eugeniy N.; Plaskon, Andrey S.; Volochnyuk, Dmitriy M.; Shivanyuk, Alexander N.; Tolmachev, Andrey A.; Sheibani, Hassan; Babaie, Maryam; Behzadi, Soheila; Dabiri, Minoo; Bahramnejad, Mahboobeh; Bashiribod, Sahareh; Hekmatshoar, Rahim; Sadjadi, Sodeh; Khorasani, Mohammad; Polyakov, Anatoliy I.; Eryomina, Vera A.; Medvedeva, Lidiya A.; Tihonova, Nadezhda I.; Listratova, Anna V.; Voskressensky, Leonid G.; Merkul, Eugen; Dorsch, Dieter; Müller, Thomas J. J.; Sheibani, Hassan; Esfandiarpoor, Zeinab; Behzadi, Soheila; Titova, Julia A.; Fedorova, Olga V.; Ovchinnikova, Irina G.; Valova, Marina S.; Koryakova, Olga V.; Rusinov, Gennady L.; Charushin, Valery N.; Hekmatshoar, Rahim; Sadjadi, Sodeh

We have been studying the development of new asymmetric two-center catalysis using rare earth alkoxides and bifunctional sugar and related ligands. In The Fourth International Conference on Multi-Component Reactions and Related Chemistry (MCR 2009), new catalytic asymmetric reactions using catalysts 1 and 2 and catalytic asymmetric syntheses of ranirestat 3 and tamiflu 4 will be presented.

A combined crossed-beam and theoretical study of the reaction dynamics of O(3P) + C2H3 → C2H2 + OH: analysis of the nascent OH products with the preferential population of the Π(A') component.

PubMed

Park, Min-Jin; Jang, Su-Chan; Choi, Jong-Ho

2012-11-28

The gas-phase reaction dynamics of ground-state atomic oxygen [O((3)P) from the photo-dissociation of NO(2)] with vinyl radicals [C(2)H(3) from the supersonic flash pyrolysis of vinyl iodide, C(2)H(3)I] has been investigated using a combination of high-resolution laser-induced fluorescence spectroscopy in a crossed-beam configuration and ab initio calculations. Unlike the previous gas-phase bulk kinetic experiments by Baulch et al. [J. Phys. Chem. Ref. Data 34, 757 (2005)], a new exothermic channel of O((3)P) + C(2)H(3) → C(2)H(2) + OH (X (2)Π: υ" = 0) has been identified for the first time, and the population analysis shows bimodal nascent rotational distributions of OH products with low- and high-N" components with a ratio of 2.4:1. No spin-orbit propensities were observed, and the averaged ratios of Π(A('))∕Π(A") were determined to be 1.66 ± 0.27. On the basis of computations at the CBS-QB3 theory level and comparison with prior theory, the microscopic mechanisms responsible for the nascent populations can be understood in terms of two competing dynamical pathways: a direct abstraction process in the low-N" regime as the major pathway and an addition-complex forming process in the high-N" regime as the minor pathway. Particularly, during the bond cleavage process of the weakly bound van der Waals complex C(2)H(2)-OH, the characteristic pathway from the low dihedral-angle geometry was consistent with the observed preferential population of the Π(A') component in the nascent OH products. A molecular-level discussion of the reactivity, mechanism, and dynamical features of the title reaction are presented together with a comparison to gas-phase oxidation reactions of a series of prototypical hydrocarbon radicals.

Toward the automated generation of genome-scale metabolic networks in the SEED.

PubMed

DeJongh, Matthew; Formsma, Kevin; Boillot, Paul; Gould, John; Rycenga, Matthew; Best, Aaron

2007-04-26

Current methods for the automated generation of genome-scale metabolic networks focus on genome annotation and preliminary biochemical reaction network assembly, but do not adequately address the process of identifying and filling gaps in the reaction network, and verifying that the network is suitable for systems level analysis. Thus, current methods are only sufficient for generating draft-quality networks, and refinement of the reaction network is still largely a manual, labor-intensive process. We have developed a method for generating genome-scale metabolic networks that produces substantially complete reaction networks, suitable for systems level analysis. Our method partitions the reaction space of central and intermediary metabolism into discrete, interconnected components that can be assembled and verified in isolation from each other, and then integrated and verified at the level of their interconnectivity. We have developed a database of components that are common across organisms, and have created tools for automatically assembling appropriate components for a particular organism based on the metabolic pathways encoded in the organism's genome. This focuses manual efforts on that portion of an organism's metabolism that is not yet represented in the database. We have demonstrated the efficacy of our method by reverse-engineering and automatically regenerating the reaction network from a published genome-scale metabolic model for Staphylococcus aureus. Additionally, we have verified that our method capitalizes on the database of common reaction network components created for S. aureus, by using these components to generate substantially complete reconstructions of the reaction networks from three other published metabolic models (Escherichia coli, Helicobacter pylori, and Lactococcus lactis). We have implemented our tools and database within the SEED, an open-source software environment for comparative genome annotation and analysis. Our method sets the stage for the automated generation of substantially complete metabolic networks for over 400 complete genome sequences currently in the SEED. With each genome that is processed using our tools, the database of common components grows to cover more of the diversity of metabolic pathways. This increases the likelihood that components of reaction networks for subsequently processed genomes can be retrieved from the database, rather than assembled and verified manually.

A 3D numerical study of LO2/GH2 supercritical combustion in the ONERA-Mascotte Test-rig configuration

NASA Astrophysics Data System (ADS)

Benmansour, Abdelkrim; Liazid, Abdelkrim; Logerais, Pierre-Olivier; Durastanti, Jean-Félix

2016-02-01

Cryogenic propellants LOx/H2 are used at very high pressure in rocket engine combustion. The description of the combustion process in such application is very complex due essentially to the supercritical regime. Ideal gas law becomes invalid. In order to try to capture the average characteristics of this combustion process, numerical computations are performed using a model based on a one-phase multi-component approach. Such work requires fluid properties and a correct definition of the mixture behavior generally described by cubic equations of state with appropriated thermodynamic relations validated against the NIST data. In this study we consider an alternative way to get the effect of real gas by testing the volume-weighted-mixing-law with association of the component transport properties using directly the NIST library data fitting including the supercritical regime range. The numerical simulations are carried out using 3D RANS approach associated with two tested turbulence models, the standard k-Epsilon model and the realizable k-Epsilon one. The combustion model is also associated with two chemical reaction mechanisms. The first one is a one-step generic chemical reaction and the second one is a two-step chemical reaction. The obtained results like temperature profiles, recirculation zones, visible flame lengths and distributions of OH species are discussed.

Integrating impairments in reaction time and executive function using a diffusion model framework

PubMed Central

Karalunas, Sarah L.; Huang-Pollock, Cynthia L.

2013-01-01

Using Ratcliff’s diffusion model and ex-Gaussian decomposition, we directly evaluate the role individual differences in reaction time (RT) distribution components play in the prediction of inhibitory control and working memory (WM) capacity in children with and without ADHD. Children with (n=92, x̄ age= 10.2 years, 67% male) and without ADHD (n=62, x̄ age=10.6 years, 46% male) completed four tasks of WM and a stop signal reaction time (SSRT) task. Children with ADHD had smaller WM capacities and less efficient inhibitory control. Diffusion model analyses revealed that children with ADHD had slower drift rates (v) and faster non-decision times (Ter), but there were no group differences in boundary separations (a). Similarly, using an ex-Gaussian approach, children with ADHD had larger τ values than non-ADHD controls, but did not differ in µ or σ distribution components. Drift rate mediated the association between ADHD status and performance on both inhibitory control and WM capacity. τ also mediated the ADHD-executive function impairment associations; however, models were a poorer fit to the data. Impaired performance on RT and executive functioning tasks has long been associated with childhood ADHD. Both are believed to be important cognitive mechanisms to the disorder. We demonstrate here that drift rate, or the speed at which information accumulates towards a decision, is able to explain both. PMID:23334775

Carbon monoxide detection of chemisorbed oxygen in coal and other carbonaceous materials

USGS Publications Warehouse

Hinckley, C.C.; Wiltowski, T.; Wiltowska, T.; Ellison, D.W.; Shiley, R.H.; Wu, L.

1990-01-01

The oxidation of carbon monoxide by mildly oxidized and devolatilized coal samples was studied thermogravimetrically. The oxidation was attributed to oxygen chemisorbed on inorganic components of the coals. The reaction of CO with pyrite producing carbonyl sulphide, OCS, accompanied the oxidation. A mechanism for CO oxidation is proposed in which active oxygen chemisorbed on the inorganic components of the coal directly oxidized CO to CO2, and facilitates the chemisorption of CO on the coal as carbonate. A factor, ?? = ( 11 14) [1 - ( Wn Wc)], was derived where Wn is the sample weight loss not attributed to OCS formation, and Wc is the estimated weight of evolved CO2. This quantity is proportional to the fraction of CO2 produced by the direct oxidation of CO, and was used to compare the coal samples studied. Samples of an Illinois No. 5 coal yielded average ?? values of 0.7 and those of an Illinois No. 6 coal yielded values of 0.6, indicating that in these cases, the majority of CO2 produced came from the direct oxidation of CO. The results obtained for the coal samples are compared with a selection of carbonaceous samples for which the proposed mechanism does not apply. ?? 1990.

Novel Reagents for Multi-Component Reactions

NASA Astrophysics Data System (ADS)

Wang, Yanguang; Basso, Andrea; Nenajdenko, Valentine G.; Gulevich, Anton V.; Krasavin, Mikhail; Bushkova, Ekaterina; Parchinsky, Vladislav; Banfi, Luca; Basso, Andrea; Cerulli, Valentina; Guanti, Giuseppe; Riva, Renata; Rozentsveig, Igor B.; Rozentsveig, Gulnur N.; Popov, Aleksandr V.; Serykh, Valeriy J.; Levkovskaya, Galina G.; Cao, Song; Shen, Li; Liu, Nianjin; Wu, Jingjing; Li, Lina; Qian, Xuhong; Chen, Xiaopeng; Wang, Hongbo; Feng, Jinwu; Wang, Yanguang; Lu, Ping; Heravi, Majid M.; Sadjadi, Samaheh; Kazemizadeh, Ali Reza; Ramazani, Ali; Kudyakova, Yulia S.; Goryaeva, Marina V.; Burgart, Yanina V.; Saloutin, Victor I.; Mossetti, Riccardo; Pirali, Tracey; Tron, Gian Cesare; Rozhkova, Yulia S.; Mayorova, Olga A.; Shklyaev, Yuriy V.; Zhdanko, Alexander G.; Nenajdenko, Valentine G.; Stryapunina, Olga G.; Plekhanova, Irina V.; Glushkov, Vladimir A.; Shklyaev, Yurii V.

Ketenimines are a class of versatile and highly reactive intermediates that can participate in a variety of organic reactions, such as nucleophilic additions, radical additions, [2 + 2] and [2 + 4] cycloadditions, and sigmatropic rearrangements. In this presentation, we report on a series of multi-component reactions that involve a ketenimine intermediate. These reactions could furnish diverse heterocyclic compounds, including functionalized iminocoumarin, iminodihydroqunolines, iminothiochromens, pyrrolines, isoquinolines, pyridines, β-lactams, imino-1,2-dihydrocoumarins, and benzimidazoles.

Practical synthesis of phthalimides and benzamides by a multicomponent reaction involving arynes, isocyanides, and CO2/H2O.

PubMed

Kaicharla, Trinadh; Thangaraj, Manikandan; Biju, Akkattu T

2014-03-21

Transition-metal-free multicomponent reactions involving arynes and isocyanides with either CO2 or H2O have been reported. With CO2 as the third component, the reactions resulted in the formation of N-substituted phthalimides. The utility of water as the third component furnished benzamide derivatives in moderate to good yields. These reactions took place under mild conditions with broad scope.

The Gaseous Explosive Reaction : A Study of the Kinetics of Composite Fuels

NASA Technical Reports Server (NTRS)

Stevens, F W

1929-01-01

This report deals with the results of a series of studies of the kinetics of gaseous explosive reactions where the fuel under observation, instead of being a simple gas, is a known mixture of simple gases. In the practical application of the gaseous explosive reaction as a source of power in the gas engine, the fuels employed are composite, with characteristics that are apt to be due to the characteristics of their components and hence may be somewhat complex. The simplest problem that could be proposed in an investigation either of the thermodynamics or kinetics of the gaseous explosive reaction of a composite fuel would seem to be a separate study of the reaction characteristics of each component of the fuel and then a study of the reaction characteristics of the various known mixtures of those components forming composite fuels more and more complex. (author)

Assessing Cognitive Performance in Badminton Players: A Reproducibility and Validity Study

PubMed Central

van de Water, Tanja; Faber, Irene; Elferink-Gemser, Marije

2017-01-01

Abstract Fast reaction and good inhibitory control are associated with elite sports performance. To evaluate the reproducibility and validity of a newly developed Badminton Reaction Inhibition Test (BRIT), fifteen elite (25 ± 4 years) and nine non-elite (24 ± 4 years) Dutch male badminton players participated in the study. The BRIT measured four components: domain-general reaction time, badminton-specific reaction time, domain-general inhibitory control and badminton-specific inhibitory control. Five participants were retested within three weeks on the badminton-specific components. Reproducibility was acceptable for badminton-specific reaction time (ICC = 0.626, CV = 6%) and for badminton-specific inhibitory control (ICC = 0.317, CV = 13%). Good construct validity was shown for badminton-specific reaction time discriminating between elite and non-elite players (F = 6.650, p < 0.05). Elite players did not outscore non-elite players on domain-general reaction time nor on both components of inhibitory control (p > 0.05). Concurrent validity for domain-general reaction time was good, as it was associated with a national ranking for elite (p = 0.70, p < 0.01) and non-elite (p = 0.70, p < 0.05) players. No relationship was found between the national ranking and badminton-specific reaction time, nor both components of inhibitory control (p > 0.05). In conclusion, reproducibility and validity of inhibitory control assessment was not confirmed, however, the BRIT appears a reproducible and valid measure of reaction time in badminton players. Reaction time measured with the BRIT may provide input for training programs aiming to improve badminton players’ performance. PMID:28210347

Assessing Cognitive Performance in Badminton Players: A Reproducibility and Validity Study.

PubMed

van de Water, Tanja; Huijgen, Barbara; Faber, Irene; Elferink-Gemser, Marije

2017-01-01

Fast reaction and good inhibitory control are associated with elite sports performance. To evaluate the reproducibility and validity of a newly developed Badminton Reaction Inhibition Test (BRIT), fifteen elite (25 ± 4 years) and nine non-elite (24 ± 4 years) Dutch male badminton players participated in the study. The BRIT measured four components: domain-general reaction time, badminton-specific reaction time, domain-general inhibitory control and badminton-specific inhibitory control. Five participants were retested within three weeks on the badminton-specific components. Reproducibility was acceptable for badminton-specific reaction time (ICC = 0.626, CV = 6%) and for badminton-specific inhibitory control (ICC = 0.317, CV = 13%). Good construct validity was shown for badminton-specific reaction time discriminating between elite and non-elite players (F = 6.650, p < 0.05). Elite players did not outscore non-elite players on domain-general reaction time nor on both components of inhibitory control (p > 0.05). Concurrent validity for domain-general reaction time was good, as it was associated with a national ranking for elite (p = 0.70, p < 0.01) and non-elite (p = 0.70, p < 0.05) players. No relationship was found between the national ranking and badminton-specific reaction time, nor both components of inhibitory control (p > 0.05). In conclusion, reproducibility and validity of inhibitory control assessment was not confirmed, however, the BRIT appears a reproducible and valid measure of reaction time in badminton players. Reaction time measured with the BRIT may provide input for training programs aiming to improve badminton players' performance.

Highly efficient and recyclable basic mesoporous zeolite catalyzed condensation, hydroxylation, and cycloaddition reactions.

PubMed

Sarmah, Bhaskar; Satpati, Biswarup; Srivastava, Rajendra

2017-05-01

Crystalline mesoporous ZSM-5 zeolite was prepared in the presence of 1,4-diazabicyclo[2.2.2]octane derived multi-cationic structure directing agent. The calcined form of the mesoprous zeolite was treated with NH 4 OH to obtain basic mesoporous ZSM-5. Catalyst was characterized by the complementary combination of X-ray diffraction, N 2 -adsorption, electron microscopes, and temperature programme desorption techniques. Catalytic activity of the basic mesoporous ZSM-5 was systematically assessed using Knoevenagel condensation reaction for the synthesis a wide range of substituted styrene. Applications of the catalyst were investigated in the benzamide hydroxylation for the synthesis of carbinolamides and one-pot, multi-component condensation reaction for the synthesis of naphthopyrans. Finally, the catalyst was evaluated in the cycloaddition of CO 2 to epoxide for the synthesis of cyclic carbonates. Recycling study shows that no significant decrease in the catalytic activity was observed after five recycles. Copyright © 2017. Published by Elsevier Inc.

Skeletal Mechanism Generation of Surrogate Jet Fuels for Aeropropulsion Modeling

NASA Astrophysics Data System (ADS)

Sung, Chih-Jen; Niemeyer, Kyle E.

2010-05-01

A novel implementation for the skeletal reduction of large detailed reaction mechanisms using the directed relation graph with error propagation and sensitivity analysis (DRGEPSA) is developed and presented with skeletal reductions of two important hydrocarbon components, n-heptane and n-decane, relevant to surrogate jet fuel development. DRGEPSA integrates two previously developed methods, directed relation graph-aided sensitivity analysis (DRGASA) and directed relation graph with error propagation (DRGEP), by first applying DRGEP to efficiently remove many unimportant species prior to sensitivity analysis to further remove unimportant species, producing an optimally small skeletal mechanism for a given error limit. It is illustrated that the combination of the DRGEP and DRGASA methods allows the DRGEPSA approach to overcome the weaknesses of each previous method, specifically that DRGEP cannot identify all unimportant species and that DRGASA shields unimportant species from removal.

Ontology aided modeling of organic reaction mechanisms with flexible and fragment based XML markup procedures.

PubMed

Sankar, Punnaivanam; Aghila, Gnanasekaran

2007-01-01

The mechanism models for primary organic reactions encoding the structural fragments undergoing substitution, addition, elimination, and rearrangements are developed. In the proposed models, each and every structural component of mechanistic pathways is represented with flexible and fragment based markup technique in XML syntax. A significant feature of the system is the encoding of the electron movements along with the other components like charges, partial charges, half bonded species, lone pair electrons, free radicals, reaction arrows, etc. needed for a complete representation of reaction mechanism. The rendering of reaction schemes described with the proposed methodology is achieved with a concise XML extension language interoperating with the structure markup. The reaction scheme is visualized as 2D graphics in a browser by converting them into SVG documents enabling the desired layouts normally perceived by the chemists conventionally. An automatic representation of the complex patterns of the reaction mechanism is achieved by reusing the knowledge in chemical ontologies and developing artificial intelligence components in terms of axioms.

The requirement of ammonium or other cations linked with p-cresol sulfate for cross-reactivity with a peptide of myelin basic protein.

PubMed

Jackson, Patricia L; Cao, Ligong; Blalock, J Edwin; Whitaker, John N

2003-10-15

Urinary myelin basic protein-like material (MBPLM), so designated because of its immunoreactivity with a polyclonal antibody directed against a cryptic epitope located in residues 83-89 of myelin basic protein (MBP), exists in humans normally but increases in concentration in patients with multiple sclerosis who have progressive disease. Given its possible role in reflecting events of neural tissue destruction occurring in multiple sclerosis, urinary MBPLM is a candidate surrogate marker for this phase of the disease. Previously, it has been demonstrated that p-cresol sulfate (PCS) is the dominant component of MBPLM; however, another component(s) was essential in enabling p-cresol sulfate to have molecular mimicry with MBP peptide 83-89 detected by immunoreactivity. In the present investigation, this remaining component(s) was characterized by a combination of high performance size exclusion chromatography followed by nuclear magnetic resonance spectroscopy and shown to be ammonium. The monovalent cation ammonium could be substituted in vitro by several different monovalent and divalent cations, most notably zinc, in restoring to deprotonated p-cresol sulfate its immunoreactivity as MBPLM. These findings indicate the basis for the unexpected molecular mimicry between an epitope of an encephalitogenic protein and a complex containing a small organic molecule, p-cresol sulfate. Furthermore, the reaction of either ammonium or other cations with p-cresol sulfate may represent an in vivo process directly related to damage of axonal membranes.

Time-resolved tryptophan fluorescence in photosynthetic reaction centers from Rhodobacter sphaeroides

NASA Technical Reports Server (NTRS)

Godik, V. I.; Blankenship, R. E.; Causgrove, T. P.; Woodbury, N.

1993-01-01

Tryptophan fluorescence of reaction centers isolated from Rhodobacter sphaeroides, both stationary and time-resolved, was studied. Fluorescence kinetics were found to fit best a sum of four discrete exponential components. Half of the initial amplitude was due to a component with a lifetime of congruent to 60 ps, belonging to Trp residues, capable of efficient transfer of excitation energy to bacteriochlorophyll molecules of the reaction center. The three other components seem to be emitted by Trp ground-state conformers, unable to participate in such a transfer. Under the influence of intense actinic light, photooxidizing the reaction centers, the yield of stationary fluorescence diminished by congruent to 1.5 times, while the number of the kinetic components and their life times remained practically unchanged. Possible implications of the observed effects for the primary photosynthesis events are considered.

Test measurement of 7Be(p,γ)8B with the recoil mass separator ERNA

NASA Astrophysics Data System (ADS)

Buompane, R.; De Cesare, N.; Di Leva, A.; D'Onofrio, A.; Gialanella, L.; Romano, M.; De Cesare, M.; Duarte, J. G.; Fülöp, Zs.; Morales-Gallegos, L.; Gyürky, Gy.; Gasques, L. R.; Marzaioli, F.; Palumbo, G.; Porzio, G.; Rapagnani, D.; Roca, V.; Rogalla, D.; Romoli, M.; Sabbarese, C.; Schürmann, D.; Terrasi, F.

2018-06-01

7Be(p,γ)8B has an important role in nuclear astrophysics, having a direct impact on both the high energy component of solar neutrinos and the 7Li abundance after the Big Bang Nucleosynthesis. All direct measurements providing useful information on this reaction so far used the same approach, i.e. a proton beam on a radioactive 7Be target. The overall precision and accuracy of the estimate of the astrophysical rate of this reaction are limited by the discrepancy between the results of existing measurements, possibly due to the complicated stoichiometry and beam induced deterioration of the radioactive targets. The ERNA (European Recoil separator for Nuclear Astrophysics) collaboration planned a new experiment in inverse kinematics exploiting the intense 7Be beam available at CIRCE (Center for Isotopic Research on Cultural and Environmental heritage), Caserta, Italy. The 8B recoils are produced in a windowless hydrogen gas target and detected after the efficient mass separation provided by ERNA. Here we present the commissioning of the experimental setup and a first cross section measurement at E_{cm}≈ 812 keV.

The rhodium catalyzed three-component reaction of diazoacetates, titanium(IV) alkoxides and aldehydes.

PubMed

Lu, Chong-Dao; Liu, Hui; Chen, Zhi-Yong; Hu, Wen-Hao; Mi, Ai-Qiao

2005-05-28

The rhodium(II)-catalyzed three-component reaction of diazoacetates, titanium alkoxides and aldehydes is shown to give alpha-alkoxyl-beta-hydroxyl acid derivatives; the novel C-C bond formation reaction is proposed to occur through oxonium ylides derived from diazo compounds and titanium alkoxides, and followed by intermolecular trapping by aldehydes.

Identification of the polypeptides encoded in the unassigned reading frames 2, 4, 4L, and 5 of human mitochondrial DNA.

PubMed Central

Mariottini, P; Chomyn, A; Riley, M; Cottrell, B; Doolittle, R F; Attardi, G

1986-01-01

In previous work, antibodies prepared against chemically synthesized peptides predicted from the DNA sequence were used to identify the polypeptides encoded in three of the eight unassigned reading frames (URFs) of human mitochondrial DNA (mtDNA). In the present study, this approach has been extended to other human mtDNA URFs. In particular, antibodies directed against the NH2-terminal octapeptide of the putative URF2 product specifically precipitated component 11 of the HeLa cell mitochondrial translation products, the reaction being inhibited by the specific peptide. Similarly, antibodies directed against the COOH-terminal nonapeptide of the putative URF4 product reacted specifically with components 4 and 5, and antibodies against a COOH-terminal heptapeptide of the presumptive URF4L product reacted specifically with component 26. Antibodies against the NH2-terminal heptapeptide of the putative product of URF5 reacted with component 1, but only to a marginal extent; however, the results of a trypsin fingerprinting analysis of component 1 point strongly to this component as being the authentic product of URF5. The polypeptide assignments to the mtDNA URFs analyzed here are supported by the relative electrophoretic mobilities of proteins 11, 4-5, 26, and 1, which are those expected for the molecular weights predicted from the DNA sequence for the products of URF2, URF4, URF4L, and URF5, respectively. With the present assignment, seven of the eight human mtDNA URFs have been shown to be expressed in HeLa cells. Images PMID:3456601

Byproduct-free mass production of compound semiconductor nanowires: zinc phosphide

NASA Astrophysics Data System (ADS)

Chen, Yixi; Polinnaya, Rakesh; Vaddiraju, Sreeram

2018-05-01

A method for the mass production of compound semiconductor nanowires that involves the direct reaction of component elements in a chemical vapor deposition chamber (CVD) is presented. This method results in nanowires, without the associated production of any other byproducts such as nanoparticles or three-dimensional (3D) bulk crystals. Furthermore, no unreacted reactants remain mixed with the nanowire product in this method. This byproduct-free nanowire production thus circumvents the need to tediously purify and collect nanowires from a mixture of products/reactants after their synthesis. Demonstration made using zinc phosphide (Zn3P2) material system as an example indicated that the direct reaction of zinc microparticles with phosphorus supplied via the vapor phase results in the production of gram quantities of nanowires. To enhance thermal transport and achieve the complete reaction of zinc microparticles, while simultaneously ensuring that the microparticles do not agglomerate into macroscale zinc particles and partly remain unreacted (owing to diffusion limitations), pellets composed of mixtures of zinc and a sacrificial salt, NH4Cl, were employed as the starting material. The sublimation by decomposition of NH4Cl in the early stages of the reaction leaves a highly porous pellet of zinc composed of only zinc microparticles, which allows for inward diffusion of phosphorus/outward diffusion of zinc and the complete conversion of zinc into Zn3P2 nanowires. NH4Cl also aids in removal of any native oxide layer present on the zinc microparticles that may prevent their reaction with phosphorus. This method may be used to mass produce many other nanowires in a byproduct-free manner, besides Zn3P2.

[Consensus position document on the child with an allergic reaction after vaccination or an allergy to vaccine components].

PubMed

Echeverría Zudaire, L; Ortigosa Del Castillo, L; Alonso Lebrero, E; Álvarez García, F J; Cortés Álvarez, N; García Sánchez, N; Martorell Aragonés, A

2015-07-01

Vaccinations are one of the main public health tools for the control of vaccine-preventable diseases. If a child is labeled to have had an allergic reaction to a vaccine, the next immunizations will probably be suspended in that child, with the risks involved in this decision. The rate of severe allergic reactions is very low, ranging between 0.5-1/100,000 doses. The causes of allergic reactions to vaccines, more than the vaccine itself, are often due to residual protein components in the manufacturing process, such as gelatin or egg, and rarely to yeast or latex. Most of vaccine reactions are mild, localized at the site of injection, but in some circumstances, severe anaphylactic reactions can occur. If an immediate-type allergic reaction is suspected when vaccinating, or a child allergic to some of the vaccine components has to be vaccinated, a correct diagnosis of the possible allergy has to be made. The usual components of each vaccine should be known, in order to determine if vaccination can be performed safely on the child. Copyright © 2014 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

Lewis Acid Catalyzed Asymmetric Three-Component Coupling Reaction: Facile Synthesis of α-Fluoromethylated Tertiary Alcohols.

PubMed

Aikawa, Kohsuke; Kondo, Daisuke; Honda, Kazuya; Mikami, Koichi

2015-12-01

A chiral dicationic palladium complex is found to be an efficient Lewis acid catalyst for the synthesis of α-fluoromethyl-substituted tertiary alcohols using a three-component coupling reaction. The reaction transforms three simple and readily available components (terminal alkyne, arene, and fluoromethylpyruvate) to valuable chiral organofluorine compounds. This strategy is completely atom-economical and results in perfect regioselectivities and high enantioselectivities of the corresponding tertiary allylic alcohols in good to excellent yields. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a statistically proven injection molding method for reaction bonded silicon nitride, sintering reaction bonded silicon nitride, and sintered silicon nitride

NASA Astrophysics Data System (ADS)

Steiner, Matthias

A statistically proven, series injection molding technique for ceramic components was developed for the construction of engines and gas turbines. The flow behavior of silicon injection-molding materials was characterized and improved. Hot-isostatic-pressing reaction bonded silicon nitride (HIPRBSN) was developed. A nondestructive component evaluation method was developed. An injection molding line for HIPRBSN engine components precombustion chamber, flame spreader, and valve guide was developed. This line allows the production of small series for engine tests.

An electro-active system of immuno-assay (EASI assay) utilising self assembled monolayer modified electrodes.

PubMed

Porter, R; van der Logt, P; Howell, S; Kyröläinen-Reay, M; Badley, A

2001-12-01

Most immunoassays currently rely on optical methods for signal generation e.g. in ELISA and rapid assay formats. It has become apparent as in the Glucose sensor market that there is a need for simple direct electrical immuno-sensors. We have investigated the novel use of organic conducting monolayers used as a direct electrochemical detection support for an immuno-reaction. It was found that antibodies raised to a carbazole dimer monolayer could increase the charge movement across that monolayer surface. Antibody fragments were taken from a specific anti-carbazole antibody fragment library and combined with an antibody fragment directed to the hormone estrone 3 glucuronide (E3G), the target antigen to form a bispecific antibody fragment. The device utilised these specific antibody fragments and incorporated them on the top plate of a capillary fill format as the immuno-assay components. The immuno-reaction utilised a competition assay. Free E3G analyte in the sample displaced the bispecific antibody fragment from the immuno-surface leaving it free to bind the carbazole monolayer surface. There the binding was detected using amperometric or coulometric methods. By combining all there element it was possible to develop a sensitive immuno-assay that could detect E3G in a reproducible calibrated fashion down to 10 ng/ml.

Photosynthetic light reactions--an adjustable hub in basic production and plant immunity signaling.

PubMed

Kangasjärvi, Saijaliisa; Tikkanen, Mikko; Durian, Guido; Aro, Eva-Mari

2014-08-01

Photosynthetic efficiency is a key trait that influences the sustainable utilization of plants for energy and nutrition. By now, extensive research on photosynthetic processes has underscored important structural and functional relationships among photosynthetic thylakoid membrane protein complexes, and their roles in determining the productivity and stress resistance of plants. Photosystem II photoinhibition-repair cycle, for example, has arisen vital in protecting also Photosystem I against light-induced damage. Availability of highly sophisticated genetic, biochemical and biophysical tools has greatly expanded the catalog of components that carry out photoprotective functions in plants. On thylakoid membranes, these components encompass a network of overlapping systems that allow delicate regulation of linear and cyclic electron transfer pathways, balancing of excitation energy distribution between the two photosystems and dissipation of excess light energy in the antenna system as heat. An increasing number of reports indicate that the above mentioned mechanisms also mediate important functions in the regulation of biotic stress responses in plants. Particularly the handling of excitation energy in the light harvesting II antenna complexes appears central to plant immunity signaling. Comprehensive understanding of the underlying mechanisms and regulatory cross-talk, however, still remain elusive. This review highlights the current understanding of components that regulate the function of photosynthetic light reactions and directly or indirectly also modulate disease resistance in higher plants. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Unimolecular Reaction Pathways of a γ-Ketohydroperoxide from Combined Application of Automated Reaction Discovery Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grambow, Colin A.; Jamal, Adeel; Li, Yi -Pei

Ketohydroperoxides are important in liquid-phase autoxidation and in gas-phase partial oxidation and pre-ignition chemistry, but because of their low concentration, instability, and various analytical chemistry limitations, it has been challenging to experimentally determine their reactivity, and only a few pathways are known. In the present work, 75 elementary-step unimolecular reactions of the simplest γ-ketohydroperoxide, 3-hydroperoxypropanal, were discovered by a combination of density functional theory with several automated transition-state search algorithms: the Berny algorithm coupled with the freezing string method, single- and double-ended growing string methods, the heuristic KinBot algorithm, and the single-component artificial force induced reaction method (SC-AFIR). The presentmore » joint approach significantly outperforms previous manual and automated transition-state searches – 68 of the reactions of γ-ketohydroperoxide discovered here were previously unknown and completely unexpected. All of the methods found the lowest-energy transition state, which corresponds to the first step of the Korcek mechanism, but each algorithm except for SC-AFIR detected several reactions not found by any of the other methods. We show that the low-barrier chemical reactions involve promising new chemistry that may be relevant in atmospheric and combustion systems. Our study highlights the complexity of chemical space exploration and the advantage of combined application of several approaches. Altogether, the present work demonstrates both the power and the weaknesses of existing fully automated approaches for reaction discovery which suggest possible directions for further method development and assessment in order to enable reliable discovery of all important reactions of any specified reactant(s).« less

Unimolecular Reaction Pathways of a γ-Ketohydroperoxide from Combined Application of Automated Reaction Discovery Methods

DOE PAGES

Grambow, Colin A.; Jamal, Adeel; Li, Yi -Pei; ...

2017-12-22

Ketohydroperoxides are important in liquid-phase autoxidation and in gas-phase partial oxidation and pre-ignition chemistry, but because of their low concentration, instability, and various analytical chemistry limitations, it has been challenging to experimentally determine their reactivity, and only a few pathways are known. In the present work, 75 elementary-step unimolecular reactions of the simplest γ-ketohydroperoxide, 3-hydroperoxypropanal, were discovered by a combination of density functional theory with several automated transition-state search algorithms: the Berny algorithm coupled with the freezing string method, single- and double-ended growing string methods, the heuristic KinBot algorithm, and the single-component artificial force induced reaction method (SC-AFIR). The presentmore » joint approach significantly outperforms previous manual and automated transition-state searches – 68 of the reactions of γ-ketohydroperoxide discovered here were previously unknown and completely unexpected. All of the methods found the lowest-energy transition state, which corresponds to the first step of the Korcek mechanism, but each algorithm except for SC-AFIR detected several reactions not found by any of the other methods. We show that the low-barrier chemical reactions involve promising new chemistry that may be relevant in atmospheric and combustion systems. Our study highlights the complexity of chemical space exploration and the advantage of combined application of several approaches. Altogether, the present work demonstrates both the power and the weaknesses of existing fully automated approaches for reaction discovery which suggest possible directions for further method development and assessment in order to enable reliable discovery of all important reactions of any specified reactant(s).« less

Vaccine allergy.

PubMed

Caubet, Jean-Christoph; Ponvert, Claude

2014-08-01

Overdiagnosis of vaccine allergy is considered a major public health problem. This article discusses the different types of allergic reactions after immunization based on the timing (immediate vs nonimmediate) and the extent of the reaction (local vs systemic). The vaccine components potentially responsible for an allergic reaction are discussed, as well as the management of patients with a history of reaction to a specific vaccine and those with a history of allergy to one of the vaccine components. Copyright © 2014 Elsevier Inc. All rights reserved.

No direct by maternal effects interaction detected for pre-weaning growth in Romane sheep using a reaction norm model.

PubMed

David, Ingrid; Bouvier, Frédéric; Ricard, Edmond; Ruesche, Julien; Weisbecker, Jean-Louis

2013-09-30

The pre-weaning growth of lambs, an important component of meat production, depends on maternal and direct effects. These effects cannot be observed directly and models used to study pre-weaning growth assume that they are additive. However, it is reasonable to suggest that the influence of direct effects on growth may differ depending on the value of maternal effects i.e. an interaction may exist between the two components. To test this hypothesis, an experiment was carried out in Romane sheep in order to obtain observations of maternal phenotypic effects (milk yield and milk quality) and pre-weaning growth of the lambs. The experiment consisted of mating ewes that had markedly different maternal genetic effects with rams that contributed very different genetic effects in four replicates of a 3 × 2 factorial plan. Milk yield was measured using the lamb suckling weight differential technique and milk composition (fat and protein contents) was determined by infrared spectroscopy at 15, 21 and 35 days after lambing. Lambs were weighed at birth and then at 15, 21 and 35 days. An interaction between genotype (of the lamb) and environment (milk yield and quality) for average daily gain was tested using a restricted likelihood ratio test, comparing a linear reaction norm model (interaction model) to a classical additive model (no interaction model). A total of 1284 weights of 442 lambs born from 166 different ewes were analysed. On average, the ewes produced 2.3 ± 0.8 L milk per day. The average protein and fat contents were 50 ± 4 g/L and 60 ± 18 g/L, respectively. The mean 0-35 day average daily gain was 207 ± 46 g/d. Results of the restricted likelihood ratio tests did not highlight any significant interactions between the genotype of the lambs and milk production of the ewe. Our results support the hypothesis of additivity of maternal and direct effects on growth that is currently applied in genetic evaluation models.

Impact of Temperature and Non-Gaussian Statistics on Electron Transfer in Donor–Bridge–Acceptor Molecules

DOE PAGES

Waskasi, Morteza M.; Newton, Marshall D.; Matyushov, Dmitry V.

2017-03-16

A combination of experimental data and theoretical analysis provides evidence of a bell-shaped kinetics of electron transfer in the Arrhenius coordinates ln k vs 1/T . This kinetic law is a temperature analog of the familiar Marcus bell-shaped dependence based on ln k vs the reaction free energy. These results were obtained for reactions of intramolecular charge shift between the donor and acceptor separated by a rigid spacer studied experimentally by Miller and co-workers. The non-Arrhenius kinetic law is a direct consequence of the solvent reorganization energy and reaction driving force changing approximately as hyperbolic functions with temperature. The reorganizationmore » energy decreases and the driving force increases when temperature is increased. The point of equality between them marks the maximum of the activationless reaction rate. Reaching the consistency between the kinetic and thermodynamic experimental data requires the non-Gaussian statistics of the donor-acceptor energy gap described by the Q-model of electron transfer. Furthermore, the theoretical formalism combines the vibrational envelope of quantum vibronic transitions with the Q-model describing the classical component of the Franck-Condon factor and a microscopic solvation model of the solvent reorganization energy and the reaction free energy.« less

Influence of reaction condition on viscosity of polyurethane modified epoxy based on glycerol monooleate

NASA Astrophysics Data System (ADS)

Triwulandari, Evi; Ramadhan, Mohammad Kemilau; Ghozali, Muhammad

2017-01-01

Polyurethane modified epoxy based on glycerol monooleate (PME-GMO) was synthesized. GMO as polyol for synthesis of PME-GMO was synthesized via Fisher Esterification between oleic acid from palm oil and glycerol by using sulfuric acid as catalyst with time variation i.e. 3, 4, 5 and 6 hours at 160°C. Characterizations of GMO were carried out by analysis of acid number, hydroxyl value and FTIR. The data show that the conversion of oleic acid to ester compound is directly proportional with the increasing of reaction time but the enhancement is not significant after 3 hours. Furthermore, GMO product was used as polyol for modification of epoxy with polyurethane. Modification of epoxy with polyurethane was performed by reacted epoxy, tolonate and GMO simultaneously in one step. In this research, the reaction condition was varied i.e. time reaction (0.5; 1; 1.5; 2; 2.5 hours), composition of polyurethane used (10%, 20% toward epoxy) and rasio of tolonate and GMO (NCO/OH ratio) as component of polyurethane (1.5 and 2.5). Characterization of polyurethane modified epoxy based on glycerol (PME-GMO) was conducted by viscosity and FTIR analysis. The viscosity of PME-GMO increased with increasing of reaction time, polyurethane composition and NCO/OH ratio.

Don't Forget Product Recovery in Catalysis Research-Check the Distillation Resistance.

PubMed

Lange, Jean-Paul

2017-01-10

When investigating a new catalytic reaction, scientists may wonder if the crude reaction product can be easily separated and purified. We present here a new concept-distillation resistance-to assess the potential of distillation as a purification technique and to guide catalyst formulation or operation at the very early stage of the research. Distillation resistance, which has been developed from the analysis of 15 industrial distillation trains, can be quickly calculated with knowledge of only the product composition and atmospheric boiling points of the components. It can be directly converted into a preliminary distillation cost that considers investment and energy cost. Its application and its potential guidance in catalysis research are illustrated through a few cases studies derived from biorefinery processes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fast real-time polymerase chain reaction for quantitative detection of Lactobacillus delbrueckii bacteriophages in milk.

PubMed

Martín, Maria Cruz; del Rio, Beatriz; Martínez, Noelia; Magadán, Alfonso H; Alvarez, Miguel A

2008-12-01

One of the main microbiological problems of the dairy industry is the susceptibility of starter bacteria to virus infections. Lactobacillus delbrueckii, a component of thermophilic starter cultures used in the manufacture of several fermented dairy products, including yogurt, is also sensitive to bacteriophage attacks. To avoid the problems associated with these viruses, quick and sensitive detection methods are necessary. In the present study, a fast real-time quantitative polymerase chain reaction assay for the direct detection and quantification of L. delbrueckii phages in milk was developed. A set of primers and a TaqMan MGB probe was designed, based on the lysin gene sequence of different L. delbrueckii phages. The results show the proposed method to be a rapid (total processing time 30 min), specific and highly sensitive technique for detecting L. delbrueckii phages in milk.

An atomistic-based chemophysical environment for evaluating asphalt oxidation and antioxidants.

PubMed

Pan, Tongyan; Sun, Lu; Yu, Qifeng

2012-12-01

Asphalt binders in service conditions are subject to oxidative aging that involves the reactions between oxygen molecules and the component species of bulk asphalt. As a result, significant alterations can occur to the desired physical and/or mechanical properties of asphalt. A common practice to alleviate asphalt aging has been to employ different chemical additives or modifiers as antioxidants. The current state of knowledge in asphalt oxidation and antioxidant evaluation is centered on determining the degradation of asphalt physical properties, mainly the viscosity and ductility. Such practices, although meeting direct engineering needs, do not contribute to the fundamental understanding of the aging and anti-oxidation mechanisms, and thereby developing anti-aging strategies. From this standpoint, this study was initiated to study the chemical and physical bases of asphalt oxidation, as well as the anti-oxidation mechanisms of bio-based antioxidants using the coniferyl-alcohol lignin as an example. A quantum chemistry (QC) based chemophysical environment is developed, in which the various chemical reactions between asphalt component species and oxygen, as well as the incurred physical changes are studied. X-ray photoelectron spectroscopy (XPS) was used to validate the modified and unmodified asphalt models.

Method of controlling fusion reaction rates

DOEpatents

Kulsrud, Russell M.; Furth, Harold P.; Valeo, Ernest J.; Goldhaber, Maurice

1988-01-01

A method of controlling the reaction rates of the fuel atoms in a fusion reactor comprises the step of polarizing the nuclei of the fuel atoms in a particular direction relative to the plasma confining magnetic field. Fusion reaction rates can be increased or decreased, and the direction of emission of the reaction products can be controlled, depending on the choice of polarization direction.

Method of controlling fusion reaction rates

DOEpatents

Kulsrud, Russell M.; Furth, Harold P.; Valeo, Ernest J.; Goldhaber, Maurice

1988-03-01

A method of controlling the reaction rates of the fuel atoms in a fusion reactor comprises the step of polarizing the nuclei of the fuel atoms in a particular direction relative to the plasma confining magnetic field. Fusion reaction rates can be increased or decreased, and the direction of emission of the reaction products can be controlled, depending on the choice of polarization direction.

Unpacking personalized feedback: an exploratory study of the impact of its components and the reactions it elicits among problem drinking men who have sex with men.

PubMed

Kuerbis, Alexis Noel; Schaumberg, Katherine; Davis, Christine M; Hail, Lisa; Morgenstern, Jon

2014-03-01

Personalized feedback (PF) has demonstrated effectiveness in reducing drinking. Few studies have examined its effectiveness with adult problem drinkers or its potential mediators or moderators, including developing discrepancy. This study aimed to identify potential mediators and moderators of PF provided to adult problem drinking men who have sex with men (PDMSM). An exploratory analysis of PF provided to PDMSM in the context of modified behavioral self-control therapy (N = 90). The association of individual items of PF, severity of PF, and independently rated, in-session participant reactions to PF with drinking outcomes (mean drinks per drinking day, MDDD) were examined using correlations and logistic and linear regression. Significant pre-post differences in MDDD emerged. Other drug risk, family risk, and having an abnormal liver enzyme test result were significantly associated with proxies for developed discrepancy in expected directions; however, no PF item or reaction to PF predicted drinking outcomes. Severity of PF was not associated with participant reactions or drinking outcome. PF may be an effective intervention for PDMSM. Further research is needed to identify potential mediators and moderators of PF among adults.

Event-based text mining for biology and functional genomics

PubMed Central

Thompson, Paul; Nawaz, Raheel; McNaught, John; Kell, Douglas B.

2015-01-01

The assessment of genome function requires a mapping between genome-derived entities and biochemical reactions, and the biomedical literature represents a rich source of information about reactions between biological components. However, the increasingly rapid growth in the volume of literature provides both a challenge and an opportunity for researchers to isolate information about reactions of interest in a timely and efficient manner. In response, recent text mining research in the biology domain has been largely focused on the identification and extraction of ‘events’, i.e. categorised, structured representations of relationships between biochemical entities, from the literature. Functional genomics analyses necessarily encompass events as so defined. Automatic event extraction systems facilitate the development of sophisticated semantic search applications, allowing researchers to formulate structured queries over extracted events, so as to specify the exact types of reactions to be retrieved. This article provides an overview of recent research into event extraction. We cover annotated corpora on which systems are trained, systems that achieve state-of-the-art performance and details of the community shared tasks that have been instrumental in increasing the quality, coverage and scalability of recent systems. Finally, several concrete applications of event extraction are covered, together with emerging directions of research. PMID:24907365

Peripheral elastic and inelastic scattering of O17,18 on light targets at 12 MeV/nucleon

NASA Astrophysics Data System (ADS)

Al-Abdullah, T.; Carstoiu, F.; Gagliardi, C. A.; Tabacaru, G.; Trache, L.; Tribble, R. E.

2014-06-01

A study of interaction of neutron-rich oxygen isotopes O17,18 with light targets has been undertaken in order to determine the optical potentials needed for the transfer reaction C13(O17,O18)C12. Optical potentials in both incoming and outgoing channels have been determined in a single experiment. This transfer reaction was used to infer the direct capture rate to the F17(p,γ)Ne18 which is essential to estimate the production of F18 at stellar energies in ONe novae. The success of the asymptotic normalization coefficient (ANC) as indirect method for astrophysics is guaranteed if the reaction mechanism is peripheral and the distorted wave Born approximation cross-section calculations are warranted and stable against the optical model potential (OMP) used. We demonstrate the stability of the ANC method and the OMP results by using good-quality elastic and inelastic-scattering data with stable beams before extending the procedures to rare-ion beams. The peripherality of our reaction is inferred from a semiclassical decomposition of the total-scattering amplitude into barrier and internal barrier components. Comparison between elastic scattering of O17, O18, and O16 projectiles is made.

Revealing the Adsorption Mechanisms of Nitroxides on Ultrapure, Metallicity-Sorted Carbon Nanotubes

PubMed Central

2014-01-01

Carbon nanotubes are a natural choice as gas sensor components given their high surface to volume ratio, electronic properties, and capability to mediate chemical reactions. However, a realistic assessment of the interaction of the tube wall and the adsorption processes during gas phase reactions has always been elusive. Making use of ultraclean single-walled carbon nanotubes, we have followed the adsorption kinetics of NO2 and found a physisorption mechanism. Additionally, the adsorption reaction directly depends on the metallic character of the samples. Franck–Condon satellites, hitherto undetected in nanotube–NOx systems, were resolved in the N 1s X-ray absorption signal, revealing a weak chemisorption, which is intrinsically related to NO dimer molecules. This has allowed us to identify that an additional signal observed in the higher binding energy region of the core level C 1s photoemission signal is due to the C=O species of ketene groups formed as reaction byproducts . This has been supported by density functional theory calculations. These results pave the way toward the optimization of nanotube-based sensors with tailored sensitivity and selectivity to different species at room temperature. PMID:24404865

Heat-resistant DNA tile arrays constructed by template-directed photoligation through 5-carboxyvinyl-2′-deoxyuridine

PubMed Central

Tagawa, Miho; Shohda, Koh-ichiroh; Fujimoto, Kenzo; Sugawara, Tadashi; Suyama, Akira

2007-01-01

Template-directed DNA photoligation has been applied to a method to construct heat-resistant two-dimensional (2D) DNA arrays that can work as scaffolds in bottom-up assembly of functional biomolecules and nano-electronic components. DNA double-crossover AB-staggered (DXAB) tiles were covalently connected by enzyme-free template-directed photoligation, which enables a specific ligation reaction in an extremely tight space and under buffer conditions where no enzymes work efficiently. DNA nanostructures created by self-assembly of the DXAB tiles before and after photoligation have been visualized by high-resolution, tapping mode atomic force microscopy in buffer. The improvement of the heat tolerance of 2D DNA arrays was confirmed by heating and visualizing the DNA nanostructures. The heat-resistant DNA arrays may expand the potential of DNA as functional materials in biotechnology and nanotechnology. PMID:17982178

Palladium-tin catalysts for the direct synthesis of H 2O 2 with high selectivity

DOE PAGES

Freakley, Simon J.; He, Qian; Harrhy, Jonathan H.; ...

2016-02-25

The direct synthesis of hydrogen peroxide (H 2O 2 ) from H 2 and O 2 represents a potentially atom-efficient alternative to the current industrial indirect process. We show that the addition of tin to palladium catalysts coupled with an appropriate heat treatment cycle switches off the sequential hydrogenation and decomposition reactions, enabling selectivities of >95% toward H 2O 2 . This effect arises from a tin oxide surface layer that encapsulates small Pd-rich particles while leaving larger Pd-Sn alloy particles exposed. In conclusion, we show that this effect is a general feature for oxide-supported Pd catalysts containing an appropriatemore » second metal oxide component, and we set out the design principles for producing high-selectivity Pd-based catalysts for direct H 2O 2 production that do not contain gold.« less

Ultrasonic assisted biodiesel production of microalgae by direct transesterification

NASA Astrophysics Data System (ADS)

Kalsum, Ummu; Mahfud, Mahfud; Roesyadi, Achmad

2017-03-01

Microalgae are considered as the third generation source of biofuel and an excellent candidate for biofuel production to replace the fossil energy. The use of ultrasonic in producing biodiesel by direct transesterification of Nannochloropsis occulata using KOH as catalyst and methanol as a solvent was investigated. The following condition were determined as an optimum by experimental evaluates:: 1: 15 microalga to methanol (molar ratio); 3% catalyst concentration at temperature 40°C after 30 minute of ultrasonication. The highest yield of biodiesel produced was 30.3%. The main components of methyl ester from Nannochloropsis occulata were palmitic (C16 :0),, oleic (C18:1), stearic (C18;0), arahidic (C20:0) and myristic (C14:0). This stated that the application of ultrasounic for direct transesterificaiton of microalgae effectively reduced the reaction time compared to the reported values of conventional heating systems.

Selective chemical detection by energy modulation of sensors

DOEpatents

Stetter, J.R.; Otagawa, T.

1985-05-20

A portable instrument for use in the field in detecting, identifying, and quantifying a component of a sampled fluid includes a sensor which chemically reacts with the component of interest or a derivative thereof, an electrical heating filament for heating the sample before it is applied to the sensor, and modulating means for continuously varying the temperature of the filament (and hence the reaction rate) between two values sufficient to produce the chemical reaction. In response to this thermal modulation, the sensor produces a modulated output signal, the modulation of which is a function of the activation energy of the chemical reaction, which activation energy is specific to the particular component of interest and its concentration. Microprocessor means compares the modulated output signal with standard responses for a plurality of components to identify and quantify the particular component of interest. 4 figs.

A density functional theory study on the carbon chain growth of ethanol formation on Cu-Co (111) and (211) surfaces

NASA Astrophysics Data System (ADS)

Ren, Bohua; Dong, Xiuqin; Yu, Yingzhe; Wen, Guobin; Zhang, Minhua

2017-08-01

Calculations based on the first-principle density functional theory were carried out to study the most controversial reactions in ethanol formation from syngas on Cu-Co surfaces: CO dissociation mechanism and the key reactions of carbon chain growth of ethanol formation (HCO insertion reactions) on four model surfaces (Cu-Co (111) and (211) with Cu-rich or Co-rich surfaces) to investigate the synergy of the Cu and Co components since the complete reaction network of ethanol formation from syngas is a huge computational burden to calculate on four Cu-Co surface models. We investigated adsorption of important species involved in these reactions, activation barrier and reaction energy of H-assisted dissociation mechanism, directly dissociation of CO, and HCO insertion reactions (CHx + HCO → CHxCHO (x = 1-3)) on four Cu-Co surface models. It was found that reactions on Cu-rich (111) and (211) surfaces all have lower activation barrier in H-assisted dissociation and HCO insertion reactions, especially CH + HCO → CHCHO reaction. The PDOS of 4d orbitals of surface Cu and Co atoms of all surfaces were studied. Analysis of d-band center of Cu and Co atoms and the activation barrier data suggested the correlation between electronic property and catalytic performance. Cu-Co bimetallic with Cu-rich surface allows Co to have higher catalytic activity through the interaction of Cu and Co atom. Then it will improve the adsorption of CO and catalytic activity of Co. Thus it is more favorable to the carbon chain growth in ethanol formation. Our study revealed the factors influencing the carbon chain growth in ethanol production and explained the internal mechanism from electronic property aspect.

A new measurement of the intruder configuration in 12Be

NASA Astrophysics Data System (ADS)

Chen, J.; Lou, J. L.; Ye, Y. L.; Li, Z. H.; Pang, D. Y.; Yuan, C. X.; Ge, Y. C.; Li, Q. T.; Hua, H.; Jiang, D. X.; Yang, X. F.; Xu, F. R.; Pei, J. C.; Li, J.; Jiang, W.; Sun, Y. L.; Zang, H. L.; Zhang, Y.; Aoi, N.; Ideguchi, E.; Ong, H. J.; Lee, J.; Wu, J.; Liu, H. N.; Wen, C.; Ayyad, Y.; Hatanaka, K.; Tran, D. T.; Yamamoto, T.; Tanaka, M.; Suzuki, T.

2018-06-01

A new 11Be(d , p)12Be transfer reaction experiment was carried out in inverse kinematics at 26.9A MeV, with special efforts devoted to the determination of the deuteron target thickness and of the required optical potentials from the present elastic scattering data. In addition a direct measurement of the cross section for the 02 + state was realized by applying an isomer-tagging technique. The s-wave spectroscopic factors of 0.20-0.04+0.03 and 0.41-0.11+0.11 were extracted for the 01+ and 02+ states, respectively, in 12Be. Using the ratio of these spectroscopic factors, together with the previously reported results for the p-wave components, the single-particle component intensities in the bound 0+ states of 12Be were deduced, allowing a direct comparison with the theoretical predictions. It is evidenced that the ground-state configuration of 12Be is dominated by the d-wave intruder, exhibiting a dramatic evolution of the intruding mechanism from 11Be to 12Be, with a persistence of the N = 8 magic number broken.

Synthesis of aminocarbonyl N-acylhydrazones by a three-component reaction of isocyanides, hydrazonoyl chlorides, and carboxylic acids.

PubMed

Giustiniano, Mariateresa; Meneghetti, Fiorella; Mercalli, Valentina; Varese, Monica; Giustiniano, Francesco; Novellino, Ettore; Tron, Gian Cesare

2014-10-17

A novel one-pot multicomponent synthesis of α-aminocarbonyl N-acylhydrazones starting from readily available hydrazonoyl chlorides, isocyanides, and carboxylic acids is reported. The strategy exploits the ability of the carboxylic acid as a third component to suppress all competing reactions between nitrile imines and isocyanides, channeling the course of the reaction toward the formation of this novel class of compounds.

Chemical markup, XML, and the world wide web. 6. CMLReact, an XML vocabulary for chemical reactions.

PubMed

Holliday, Gemma L; Murray-Rust, Peter; Rzepa, Henry S

2006-01-01

A set of components (CMLReact) for managing chemical and biochemical reactions has been added to CML. These can be combined to support most of the strategies for the formal representation of reactions. The elements, attributes, and types are formally defined as XMLSchema components, and their semantics are developed. New syntax and semantics in CML are reported and illustrated with 10 examples.

[Cross-reactions between the antigens of healthy pulmonary tissue and Moraxella catarrhalis].

PubMed

Markina, O A; Iastrebova, N E; Vaneeva, N P; Liashova, V N; Ovechko, N N

2004-01-01

The study of cross-reactions between healthy pulmonary tissue antigens and Moraxella catarrhalis with the use of SDS-electrophoresis and immunoblotting revealed that in the component of healthy pulmonary tissue with a mol. wt. of 40 kD epitopes existed to which antibodies were produced, capable of cross reaction with the components of M. catarrhalis with a mol. wt. of 35 kD and 70 kD. In addition, the presence of cross-reactions between cytokeratin-8, protein contained in healthy pulmonary tissue, and M. catarrhalis antigens was established.

Integrating impairments in reaction time and executive function using a diffusion model framework.

PubMed

Karalunas, Sarah L; Huang-Pollock, Cynthia L

2013-07-01

Using Ratcliff's diffusion model and ex-Gaussian decomposition, we directly evaluate the role individual differences in reaction time (RT) distribution components play in the prediction of inhibitory control and working memory (WM) capacity in children with and without ADHD. Children with (n = 91, [Formula: see text] age = 10.2 years, 67 % male) and without ADHD (n = 62, [Formula: see text] age = 10.6 years, 46 % male) completed four tasks of WM and a stop signal reaction time (SSRT) task. Children with ADHD had smaller WM capacities and less efficient inhibitory control. Diffusion model analyses revealed that children with ADHD had slower drift rates (v) and faster non-decision times (Ter), but there were no group differences in boundary separations (a). Similarly, using an ex-Gaussian approach, children with ADHD had larger τ values than non-ADHD controls, but did not differ in μ or σ distribution components. Drift rate mediated the association between ADHD status and performance on both inhibitory control and WM capacity. τ also mediated the ADHD-executive function impairment associations; however, models were a poorer fit to the data. Impaired performance on RT and executive functioning tasks has long been associated with childhood ADHD. Both are believed to be important cognitive mechanisms to the disorder. We demonstrate here that drift rate, or the speed at which information accumulates towards a decision, is able to explain both.

Study of components and statistical reaction mechanism in simulation of nuclear process for optimized production of {sup 64}Cu and {sup 67}Ga medical radioisotopes using TALYS, EMPIRE and LISE++ nuclear reaction and evaporation codes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nasrabadi, M. N., E-mail: mnnasrabadi@ast.ui.ac.ir; Sepiani, M.

2015-03-30

Production of medical radioisotopes is one of the most important tasks in the field of nuclear technology. These radioactive isotopes are mainly produced through variety nuclear process. In this research, excitation functions and nuclear reaction mechanisms are studied for simulation of production of these radioisotopes in the TALYS, EMPIRE and LISE++ reaction codes, then parameters and different models of nuclear level density as one of the most important components in statistical reaction models are adjusted for optimum production of desired radioactive yields.

Study of components and statistical reaction mechanism in simulation of nuclear process for optimized production of 64Cu and 67Ga medical radioisotopes using TALYS, EMPIRE and LISE++ nuclear reaction and evaporation codes

NASA Astrophysics Data System (ADS)

Nasrabadi, M. N.; Sepiani, M.

2015-03-01

Production of medical radioisotopes is one of the most important tasks in the field of nuclear technology. These radioactive isotopes are mainly produced through variety nuclear process. In this research, excitation functions and nuclear reaction mechanisms are studied for simulation of production of these radioisotopes in the TALYS, EMPIRE & LISE++ reaction codes, then parameters and different models of nuclear level density as one of the most important components in statistical reaction models are adjusted for optimum production of desired radioactive yields.

Systematic assignment of thermodynamic constraints in metabolic network models

PubMed Central

Kümmel, Anne; Panke, Sven; Heinemann, Matthias

2006-01-01

Background The availability of genome sequences for many organisms enabled the reconstruction of several genome-scale metabolic network models. Currently, significant efforts are put into the automated reconstruction of such models. For this, several computational tools have been developed that particularly assist in identifying and compiling the organism-specific lists of metabolic reactions. In contrast, the last step of the model reconstruction process, which is the definition of the thermodynamic constraints in terms of reaction directionalities, still needs to be done manually. No computational method exists that allows for an automated and systematic assignment of reaction directions in genome-scale models. Results We present an algorithm that – based on thermodynamics, network topology and heuristic rules – automatically assigns reaction directions in metabolic models such that the reaction network is thermodynamically feasible with respect to the production of energy equivalents. It first exploits all available experimentally derived Gibbs energies of formation to identify irreversible reactions. As these thermodynamic data are not available for all metabolites, in a next step, further reaction directions are assigned on the basis of network topology considerations and thermodynamics-based heuristic rules. Briefly, the algorithm identifies reaction subsets from the metabolic network that are able to convert low-energy co-substrates into their high-energy counterparts and thus net produce energy. Our algorithm aims at disabling such thermodynamically infeasible cyclic operation of reaction subnetworks by assigning reaction directions based on a set of thermodynamics-derived heuristic rules. We demonstrate our algorithm on a genome-scale metabolic model of E. coli. The introduced systematic direction assignment yielded 130 irreversible reactions (out of 920 total reactions), which corresponds to about 70% of all irreversible reactions that are required to disable thermodynamically infeasible energy production. Conclusion Although not being fully comprehensive, our algorithm for systematic reaction direction assignment could define a significant number of irreversible reactions automatically with low computational effort. We envision that the presented algorithm is a valuable part of a computational framework that assists the automated reconstruction of genome-scale metabolic models. PMID:17123434

[CoCuMnOx Photocatalyzed Oxidation of Multi-component VOCs and Kinetic Analysis].

PubMed

Meng, Hai-long; Bo, Long-li; Liu, Jia-dong; Gao, Bo; Feng, Qi-qi; Tan, Na; Xie, Shuai

2016-05-15

Solar energy absorption coating CoCuMnOx was prepared by co-precipitation method and applied to photodegrade multi- component VOCs including toluene, ethyl acetate and acetone under visible light irradiation. The photocatalytic oxidation performance of toluene, ethyl acetate and acetone was analyzed and reaction kinetics of VOCs were investigated synchronously. The research indicated that removal rates of single-component toluene, ethyl acetate and acetone were 57%, 62% and 58% respectively under conditions of 400 mg · m⁻³ initial concentration, 120 mm illumination distance, 1 g/350 cm² dosage of CoCuMnOx and 6 h of irradiation time by 100 W tungsten halogen lamp. Due to the competition among different VOCs, removal efficiencies in three-component mixture were reduced by 5%-26% as compared with single VOC. Degradation processes of single-component VOC and three-component VOCs both fitted pseudo first order reaction kinetics, and kinetic constants of toluene, ethyl acetate and acetone were 0.002, 0.002 8 and 0.002 33 min⁻¹ respectively under single-component condition. Reaction rates of VOCs in three-component mixture were 0.49-0.88 times of single components.

Multi-Axis Thrust Measurements of the EO-1 Pulsed Plasma Thruster

NASA Technical Reports Server (NTRS)

Arrington, Lynn A.; Haag, Thomas W.

1999-01-01

Pulsed plasma thrusters are low thrust propulsive devices which have a high specific impulse at low power. A pulsed plasma thruster is currently scheduled to fly as an experiment on NASA's Earth Observing-1 satellite mission. The pulsed plasma thruster will be used to replace one of the reaction wheels. As part of the qualification testing of the thruster it is necessary to determine the nominal thrust as a function of charge energy. These data will be used to determine control algorithms. Testing was first completed on a breadboard pulsed plasma thruster to determine nominal or primary axis thrust and associated propellant mass consumption as a function of energy and then later to determine if any significant off-axis thrust component existed. On conclusion that there was a significant off-axis thrust component with the bread-board in the direction of the anode electrode, the test matrix was expanded on the flight hardware to include thrust measurements along all three orthogonal axes. Similar off-axis components were found with the flight unit.

Ceramic combustor mounting

DOEpatents

Hoffman, Melvin G.; Janneck, Frank W.

1982-01-01

A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

Intense, directed neutron beams from a laser-driven neutron source at PHELIX

NASA Astrophysics Data System (ADS)

Kleinschmidt, A.; Bagnoud, V.; Deppert, O.; Favalli, A.; Frydrych, S.; Hornung, J.; Jahn, D.; Schaumann, G.; Tebartz, A.; Wagner, F.; Wurden, G.; Zielbauer, B.; Roth, M.

2018-05-01

Laser-driven neutrons are generated by the conversion of laser-accelerated ions via nuclear reactions inside a converter material. We present results from an experimental campaign at the PHELIX laser at GSI in Darmstadt where protons and deuterons were accelerated from thin deuterated plastic foils with thicknesses in the μm and sub-μm range. The neutrons were generated inside a sandwich-type beryllium converter, leading to reproducible neutron numbers around 1011 neutrons per shot. The angular distribution was measured with a high level of detail using up to 30 bubble detectors simultaneously. It shows a laser forward directed component of up to 1.42 × 1010 neutrons per steradian, corresponding to a dose of 43 mrem scaled to a distance of 1 m from the converter.

Cascade redox flow battery systems

DOEpatents

Horne, Craig R.; Kinoshita, Kim; Hickey, Darren B.; Sha, Jay E.; Bose, Deepak

2014-07-22

A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytes expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.

Spin-labelled diketopiperazines and peptide-peptoid chimera by Ugi-multi-component-reactions.

PubMed

Sultani, Haider N; Haeri, Haleh H; Hinderberger, Dariush; Westermann, Bernhard

2016-12-28

For the first time, spin-labelled coumpounds have been obtained by isonitrile-based multi component reactions (IMCRs). The typical IMCR Ugi-protocols offer a simple experimental setup allowing structural variety by which labelled diketopiperazines (DKPs) and peptide-peptoid chimera have been synthesized. The reaction keeps the paramagnetic spin label intact and offers a simple and versatile route to a large variety of new and chemically diverse spin labels.

The influenced of reaction time on the degradation of palm oil empty fruit bunch (EFB) in hydrothermal carbonization

NASA Astrophysics Data System (ADS)

Sarwono, Rakhman; Kurniawan, Hendris Hendarsyah

2017-11-01

Hydrothermal carbonization (HTC) of empty fruit bunch (EFB) of palm oil in different reaction times were investigated. Experiments were carried out in an autoclave at different reaction time of 3,6,9, 15, 20, 25 and 40 hours. With a fixed solid/liquid ratio of 5 gram of EFB in 50 ml water as a solvent, and temperature reaction of 250 °C. Increase the reaction time the soluble products are also increased. The liquid products were analyzed using GCMS to determine the chemical composition. The chemical composition were greatly affected by the reaction time. The main component was glycolic acid, by increasing the reaction time made the varieties of chemical compositions in liquid products, especially for the glycolic acid component, it was decreased slightly. The higher heating value (HHV) also increase slighly by increasing the reaction time both solid and liquid products.

Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

NASA Astrophysics Data System (ADS)

Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

2017-04-01

Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barata-Vallejo, Sebastian; Ferreri, Carla; Zhang, Tao

Important biological consequences are related to the reaction of HO radicals with methionine (Met). Several fundamental aspects remain to be defined when Met is an amino acid residue incorporated in the interior of peptides and proteins. The present study focuses on Gly-Met-Gly, the simplest peptide where Met is not a terminal residue. The reactions of HO with Gly-Met-Gly and its N-acetyl derivative were studied by pulse radiolysis technique. The transient absorption spectra were resolved into contributions from specific components of radical intermediates. Moreover, a detailed product analysis is provided for the first time for Met-containing peptides in radiolytic studies tomore » support the mechanistic proposal. By parallel radiolytical and electrochemical reactions and consequent product identification, the formation of sulfoxide attributed to the direct HO radical attack on the sulfide functionality of the Met residue could be excluded, with the in situ generated hydrogen peroxide responsible for this oxidation. LC–MS and high resolution MS/MS were powerful analytical tools to envisage the structures of five products, thus allowing to complete the mechanistic picture of the overall Met-containing peptide reactivity.« less

The algorithm of numerical calculation of constraints reactions in a dynamic system of transport machine

NASA Astrophysics Data System (ADS)

Akhtulov, A. L.

2018-01-01

The questions of construction and practical application of the automation system for the design of components and aggregates for the construction of transport vehicles are considered, taking into account their dynamic characteristics. Based on the results of the studies, a unified method for determining the reactions of bonds of a complex spatial structure is proposed. The technique, based on the method of substructures, allows us to determine the values of the transfer functions taking into account the reactions of the bonds. After the carried out researches it is necessary to note, that such approach gives the most satisfactory results and can be used for calculations of complex mechanical systems of machines and units of different purposes. The directions of increasing the degree of validity of technical decisions are shown, especially in the early stages of design, when the cost of errors is high, with careful thorough working out of all the elements of the design, which is really feasible only on the basis of automation of design and technological work.

PA-Tb-Cu MOF as luminescent nanoenzyme for catalytic assay of hydrogen peroxide.

PubMed

Qi, Zewan; Wang, Li; You, Qi; Chen, Yang

2017-10-15

Metal organic frameworks (MOFs) with flexible structures and components have aroused great interest in designing functional materials. In this work, we designed and made a kind of PA-Tb-Cu MOF nanoenzyme capable of emitting fluorescence for the catalytic reaction of hydrogen peroxide (H 2 O 2 ). Luminescent Tb 3+ , catalytic Cu 2+ and bridging ligand were assembled and integrated into a single material nanoenzyme. This PA-Tb-Cu MOF nanoenzyme not only possessed excellent catalytic activity comparable to horseradish peroxidase but also can real-time fluorescently indicate the concentration of H 2 O 2 as low as 0.2µM during catalysis. Luminescent PA-Tb-Cu MOF nanoenzyme did not need a common combined use of natural/artificial enzymes and chromogenic reactions for the quantification of H 2 O 2 in widely-used enzyme-catalytic reactions. The present strategy assembled directly from functional ions/molecules provides a new way for the design and development of smart, multifunctional artificial enzymes for wide applications in biocatalysis, bioassays and nano-biomedicine. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent advances in heterocycle generation using the efficient Ugi multiple-component condensation reaction.

PubMed

Tempest, Paul A

2005-11-01

The current trend of rising research spending and falling numbers of novel chemical entities continues to drive efforts aimed at increasing efficiency in the drug discovery process. Strategic issues, such as assigning resources to poorly validated targets have been implicated in the declining productivity of recent years. Tactical approaches employed to improve this situation include attempts to speed the discovery process toward decision points in a timely manner. Accelerating the optimization of high-throughput screening hits is a goal in streamlining the discovery process, and the use of multiple-component condensation (MCC) reactions have proved useful toward this end. MCC reactions are powerful and efficient tools for the generation of diverse compound sets. Collections of compounds can be synthesized with all of the required diversity elements included in a single synthetic step. One of the most widely investigated MCC reactions is the Ugi four-component condensation. This review highlights disclosures of the Ugi reaction published over the past two years (2003 to 2005) in three areas: (i) Ugi reaction in conjunction with post-condensation cyclization; (ii) bifunctional condensations leading to heterocyclic cores; and (iii) general findings relating to linear products or interesting improvements in the basic Ugi reaction.

Identifying geochemical processes using End Member Mixing Analysis to decouple chemical components for mixing ratio calculations

NASA Astrophysics Data System (ADS)

Pelizardi, Flavia; Bea, Sergio A.; Carrera, Jesús; Vives, Luis

2017-07-01

Mixing calculations (i.e., the calculation of the proportions in which end-members are mixed in a sample) are essential for hydrological research and water management. However, they typically require the use of conservative species, a condition that may be difficult to meet due to chemical reactions. Mixing calculation also require identifying end-member waters, which is usually achieved through End Member Mixing Analysis (EMMA). We present a methodology to help in the identification of both end-members and such reactions, so as to improve mixing ratio calculations. The proposed approach consists of: (1) identifying the potential chemical reactions with the help of EMMA; (2) defining decoupled conservative chemical components consistent with those reactions; (3) repeat EMMA with the decoupled (i.e., conservative) components, so as to identify end-members waters; and (4) computing mixing ratios using the new set of components and end-members. The approach is illustrated by application to two synthetic mixing examples involving mineral dissolution and cation exchange reactions. Results confirm that the methodology can be successfully used to identify geochemical processes affecting the mixtures, thus improving the accuracy of mixing ratios calculations and relaxing the need for conservative species.

Resonance dependence of gravitropicreactionof cress roots in weak combined magnetic fields.

NASA Astrophysics Data System (ADS)

Bogatina, N. I.; Sheykina, N. V.; Kordyum, E. L.

The gravitropic reaction of cress was studied in combined magnetic fields, that is the static magnetic field of the order of Earth's one and parallel to it alternating magnetic field. The frequency region for alternating magnetic field was varied in wide diapason ( from 1 Hz up to 45 Hz). The magnitude of alternating magnetic field was equal to 6 microT. The magnetic field conditions were well reproducible. For this purpose the external magnetic field was shielded in the work volume and artificial magnetic field was created in the volume. Both ferromagnetic metal shield and superconductive one with warm volume for work were used. The magnetic noises inside both of ferromagnetic metal and superconductive shields were measured to provide the well reproducible characteristics of artificial field created in the work volume. The objects of investigation were the roots of cress after 2-3-days germination. They were located in the closed humid room, that was located inside the shield in the artificially created magnetic field. All roots were in the darkness. For control we used the analogous roots located in the analogous volume but only in the static magnetic field of the Earth. We measured the divergence angle of the root from its primary direction of growing. We obtained the following results. The curve of dependence of measured angles on the frequency of alternating component of magnetic field had series of sharp peaks. These peaks were well reproducible and their location depended on the magnitude of the static component of magnetic field. The frequency of peak location is in direct proportion with its magnitude. The analysis showed that the location of peaks coincided very well with the cyclotron frequencies of the following ions: Ca+2, Cu+1 , K+1: Fe+3: Ag+1: and with the cyclotron frequencies of ions of phytohormons such as ions of indolile-acetic acid, abscise acid and gibberellins. Some quantitive analogies between the gravitropic process and the effect of combined magnetic field are discussed at the molecular level. In particularly it was shown that in the gravity field the pressure difference between the upper and down parts of the root was of the order of the pressure difference created by the Lorenz force. The displacement of the point where the pressure approached the maximum value on membrane surface could lead to the changes in the ion transport direction and so to the changes of the gravitropic reaction direction. The possibilities of the method for the studying the gravitropic reaction were discussed.

Induced radioactivity of LDEF materials and structural components

NASA Technical Reports Server (NTRS)

Harmon, B. A.; Laird, C. E.; Fishman, G. J.; Parnell, T. A.; Camp, D. C.; Frederick, C. E.; Hurley, D. L.; Lindstrom, D. J.; Moss, C. E.; Reedy, R. C.;

10B+α states with chain-like structures in 14N

NASA Astrophysics Data System (ADS)

Kanada-En'yo, Yoshiko

2015-12-01

I investigate 10B+α -cluster states of 14N with a 10B+α -cluster model. Near the α -decay threshold energy, I obtain Kπ=3+ and Kπ=1+ rotational bands having 10B(3+) +α and 10B(1+) +α components, respectively. I assign the bandhead state of the Kπ=3+ band to the experimental 3+ at Ex=13.19 MeV of 14N observed in α scattering reactions by 10B and show that the calculated α -decay width is consistent with the experimental data. I discuss an α -cluster motion around the 10B cluster and show that the Kπ=3+ and Kπ=1+ rotational bands contain an enhanced component of a linear-chain 3 α configuration, in which an α cluster is localized in the longitudinal direction around the deformed 10B cluster.

The influence of reactive side products on the electrooxidation of methanol--a combined in situ infrared spectroscopy and online mass spectrometry study.

PubMed

Reichert, R; Schnaidt, J; Jusys, Z; Behm, R J

2014-07-21

Aiming at a better understanding of the impact of reaction intermediates and reactive side products on electrocatalytic reactions under conditions characteristic for technical applications, i.e., at high reactant conversions, we have investigated the electrooxidation of methanol on a Pt film electrode in mixtures containing defined concentrations of the reaction intermediates formaldehyde or formic acid. Employing simultaneous in situ infrared spectroscopy and online mass spectrometry in parallel to voltammetric measurements, we examined the effects of the latter molecules on the adlayer build-up and composition and on the formation of volatile reaction products CO2 and methylformate, as well as on the overall reaction rate. To assess the individual contributions of each component, we used isotope labeling techniques, where one of the two C1 components in the mixtures of methanol with either formaldehyde or formic acid was (13)C-labeled. The data reveal pronounced effects of the additional components formaldehyde and formic acid on the reaction, although their concentration was much lower (10%) than that of the main reactant methanol. Most important, the overall Faradaic current responses and the amounts of CO2 formed upon oxidation of the mixtures are always lower than the sums of the contributions from the individual components, indicative of a non-additive behavior of both Faradaic current and CO2 formation in the mixtures. Mechanistic reasons and consequences for reactions in a technical reactor, with high reactant conversion, are discussed.

Investigation of the Hoyle state in12C with a new hodoscope detector

NASA Astrophysics Data System (ADS)

Dell'Aquila, D.; Lombardo, I.; Vigilante, M.; De Luca, M.; Acosta, L.; Agodi, C.; Cappuzzello, F.; Carbone, D.; Cavallaro, M.; Cherubini, S.; Cvetinovic, A.; D'Agata, G.; Francalanza, L.; Guardo, G. L.; Gulino, M.; Indelicato, I.; La Cognata, M.; Lamia, L.; Ordine, A.; Pizzone, R.; Puglia, S.; Rapisarda, G.; Romano, S.; Santagati, G.; Spartà, R.; Spitaleri, C.; Tumino, A.; Verde, G.

2017-07-01

The {0}2+ state in12C (7.654MeV, the Hoyle state) is important for the understanding of clustering phenomena in nuclei. The pronounced cluster nature of this state allows the triple-α process in stars with a reaction rate regulated by its structure properties. To precisely estimate the direct component in the 3α decay mechanism of the Hoyle state, we developed a new experiment using the14N(d,α)12C reaction at 10.5MeV. An anti-coincidence telescope was used to identify the α ejectiles leading the residual12C in the Hoyle state, while its decays in 3α were studied by means of a new hodoscope of silicon detectors, superOSCAR, placed in kinematical coincidence to fully reconstruct the events. Details of the experiment and preliminary results are discussed in the text.

Possibility of determination of the level of antioxidants in human body using spectroscopic methods

NASA Astrophysics Data System (ADS)

Timofeeva, E.; Gorbunova, E.

2016-08-01

In this work, the processes of antioxidant defence against aggressive free radicals in human body were investigated theoretically; and the existing methods of diagnosis of oxidative stress and disturbance of antioxidant activity were reviewed. Also, the kinetics of free radical reactions in the oxidation of luminol and interaction antioxidants (such as chlorophyll in the multicomponent system of plant's leaves and ubiquinone) with the UV radiation were investigated experimentally by spectroscopic method. The results showed that this method is effective for recording the luminescence of antioxidants, free radicals, chemiluminescent reactions and fluorescence. In addition these results reveal new opportunities for the study of the antioxidant activity and antioxidant balance in a multicomponent system by allocating features of the individual components in spectral composition. A creation of quality control method for drugs, that are required for oxidative stress diagnosis, is a promising direction in the development of given work.

Biologically tunable reactivity of energetic nanomaterials using protein cages.

PubMed

Slocik, Joseph M; Crouse, Christopher A; Spowart, Jonathan E; Naik, Rajesh R

2013-06-12

The performance of aluminum nanomaterial based energetic formulations is dependent on the mass transport, diffusion distance, and stability of reactive components. Here we use a biologically inspired approach to direct the assembly of oxidizer loaded protein cages onto the surface of aluminum nanoparticles to improve reaction kinetics by reducing the diffusion distance between the reactants. Ferritin protein cages were loaded with ammonium perchlorate (AP) or iron oxide and assembled with nAl to create an oxidation-reduction based energetic reaction and the first demonstration of a nanoscale biobased thermite material. Both materials showed enhanced exothermic behavior in comparison to nanothermite mixtures of bulk free AP or synthesized iron oxide nanopowders prepared without the use of ferritin. In addition, by utilizing a layer-by-layer (LbL) process to build multiple layers of protein cages containing iron oxide and iron oxide/AP on nAl, stoichiometric conditions and energetic performance can be optimized.

Development of a Two-Wheel Contingency Mode for the MAP Spacecraft

NASA Technical Reports Server (NTRS)

Starin, Scott R.; ODonnell, James R., Jr.; Bauer, Frank (Technical Monitor)

2002-01-01

The Microwave Anisotropy Probe (MAP) is a follow-on mission to the Cosmic Background Explorer (COBE), and is currently collecting data from its orbit near the second Sun-Earth libration point. Due to limited mass, power, and financial resources, a traditional reliability concept including fully redundant components was not feasible for MAP. Instead, the MAP design employs selective hardware redundancy in tandem with contingency software modes and algorithms to improve the odds of mission success. One direction for such improvement has been the development of a two-wheel backup control strategy. This strategy would allow MAP to position itself for maneuvers and collect science data should one of its three reaction wheels fail. Along with operational considerations, the strategy includes three new control algorithms. These algorithms would use the remaining attitude control actuators-thrusters and two reaction wheels-in ways that achieve control goals while minimizing adverse impacts on the functionality of other subsystems and software.

Inflammation--a lifelong companion. Attempt at a non-analytical holistic view.

PubMed

Ferencík, M; Stvrtinová, V; Hulín, I; Novák, M

2007-01-01

Inflammation is a key component of the immune system. It has important functions in both defense and pathophysiological events maintaining the dynamic homeostasis of a host organism including its tissues, organs and individual cells. On the cellular level it is controlled by more than 400 currently known genes. Their polymorphisms and environmental conditions give rise to different genotypes in human population. Pro-inflammatory genotype, which dominates in the present population, may be advantageous in childhood but not in elderly people because it is characterized by an increased vulnerability to, and intensity of, inflammatory reactions. These reactions may be the possible reasons of chronic inflammatory diseases, especially in old age. Better understanding of complex molecular and cellular inflammatory mechanisms is indispensable for detailed knowledge of pathogenesis of many diseases, their prevention and directed drug therapy. Here we summarize the basic current knowledge on these mechanisms.

Comparative efficacy of microwave, visible light and ultrasound irradiation for green synthesis of dihydropyrimidinones in fruit juice medium

NASA Astrophysics Data System (ADS)

Pramanik, Tanay; Padan, Simarjit Kaur; Gupta, Richa; Bedi, Pooja; Singh, Gurinderpal

2017-07-01

Dihydropyrimidinones (DHPM) were synthesized via multi component condensation reaction employing urea, ethyl acetoacetate and aromatic aldehydes as reactants. Apple, pomegranate, grape juice were used individually as biodegradable, eco friendly, and green reaction medium whereas microwave, visible light and ultrasound irradiation were applied individually as green source of energy for carrying out the aforesaid reactions. It was observed that the reactions under microwave irradiation were taking minimum time to go for completion whereas the reactions under ultrasound and visible light irradiation were taking approximately same time duration to form products. This is the first of its kind study where the three different reaction methodologies based on three different sources of green energies were compared with each other for their effectiveness and efficiency towards multi component condensation reactions.

Direct vs. indirect pathway for nitrobenzene reduction reaction on a Ni catalyst surface: a density functional study.

PubMed

Mahata, Arup; Rai, Rohit K; Choudhuri, Indrani; Singh, Sanjay K; Pathak, Biswarup

2014-12-21

Density functional theory (DFT) calculations are performed to understand and address the previous experimental results that showed the reduction of nitrobenzene to aniline prefers direct over indirect reaction pathways irrespective of the catalyst surface. Nitrobenzene to aniline conversion occurs via the hydroxyl amine intermediate (direct pathway) or via the azoxybenzene intermediate (indirect pathway). Through our computational study we calculated the spin polarized and dispersion corrected reaction energies and activation barriers corresponding to various reaction pathways for the reduction of nitrobenzene to aniline over a Ni catalyst surface. The adsorption behaviour of the substrate, nitrobenzene, on the catalyst surface was also considered and the energetically most preferable structural orientation was elucidated. Our study indicates that the parallel adsorption behaviour of the molecules over a catalyst surface is preferable over vertical adsorption behaviour. Based on the reaction energies and activation barrier of the various elementary steps involved in direct or indirect reaction pathways, we find that the direct reduction pathway of nitrobenzene over the Ni(111) catalyst surface is more favourable than the indirect reaction pathway.

Mechanism reduction for multicomponent surrogates: A case study using toluene reference fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niemeyer, Kyle E.; Sung, Chih-Jen

Strategies and recommendations for performing skeletal reductions of multicomponent surrogate fuels are presented, through the generation and validation of skeletal mechanisms for a three-component toluene reference fuel. Using the directed relation graph with error propagation and sensitivity analysis method followed by a further unimportant reaction elimination stage, skeletal mechanisms valid over comprehensive and high-temperature ranges of conditions were developed at varying levels of detail. These skeletal mechanisms were generated based on autoignition simulations, and validation using ignition delay predictions showed good agreement with the detailed mechanism in the target range of conditions. When validated using phenomena other than autoignition, suchmore » as perfectly stirred reactor and laminar flame propagation, tight error control or more restrictions on the reduction during the sensitivity analysis stage were needed to ensure good agreement. In addition, tight error limits were needed for close prediction of ignition delay when varying the mixture composition away from that used for the reduction. In homogeneous compression-ignition engine simulations, the skeletal mechanisms closely matched the point of ignition and accurately predicted species profiles for lean to stoichiometric conditions. Furthermore, the efficacy of generating a multicomponent skeletal mechanism was compared to combining skeletal mechanisms produced separately for neat fuel components; using the same error limits, the latter resulted in a larger skeletal mechanism size that also lacked important cross reactions between fuel components. Based on the present results, general guidelines for reducing detailed mechanisms for multicomponent fuels are discussed.« less

Mechanism reduction for multicomponent surrogates: A case study using toluene reference fuels

DOE PAGES

Niemeyer, Kyle E.; Sung, Chih-Jen

2014-11-01

Strategies and recommendations for performing skeletal reductions of multicomponent surrogate fuels are presented, through the generation and validation of skeletal mechanisms for a three-component toluene reference fuel. Using the directed relation graph with error propagation and sensitivity analysis method followed by a further unimportant reaction elimination stage, skeletal mechanisms valid over comprehensive and high-temperature ranges of conditions were developed at varying levels of detail. These skeletal mechanisms were generated based on autoignition simulations, and validation using ignition delay predictions showed good agreement with the detailed mechanism in the target range of conditions. When validated using phenomena other than autoignition, suchmore » as perfectly stirred reactor and laminar flame propagation, tight error control or more restrictions on the reduction during the sensitivity analysis stage were needed to ensure good agreement. In addition, tight error limits were needed for close prediction of ignition delay when varying the mixture composition away from that used for the reduction. In homogeneous compression-ignition engine simulations, the skeletal mechanisms closely matched the point of ignition and accurately predicted species profiles for lean to stoichiometric conditions. Furthermore, the efficacy of generating a multicomponent skeletal mechanism was compared to combining skeletal mechanisms produced separately for neat fuel components; using the same error limits, the latter resulted in a larger skeletal mechanism size that also lacked important cross reactions between fuel components. Based on the present results, general guidelines for reducing detailed mechanisms for multicomponent fuels are discussed.« less

A combined crossed-beam and theoretical study of the reaction dynamics of O(3P) + C2H3 → C2H2 + OH: Analysis of the nascent OH products with the preferential population of the Π(A') component

NASA Astrophysics Data System (ADS)

Park, Min-Jin; Jang, Su-Chan; Choi, Jong-Ho

2012-11-01

The gas-phase reaction dynamics of ground-state atomic oxygen [O(3P) from the photo-dissociation of NO2] with vinyl radicals [C2H3 from the supersonic flash pyrolysis of vinyl iodide, C2H3I] has been investigated using a combination of high-resolution laser-induced fluorescence spectroscopy in a crossed-beam configuration and ab initio calculations. Unlike the previous gas-phase bulk kinetic experiments by Baulch et al. [J. Phys. Chem. Ref. Data 34, 757 (2005)], 10.1063/1.1748524, a new exothermic channel of O(3P) + C2H3 → C2H2 + OH (X 2Π: υ″ = 0) has been identified for the first time, and the population analysis shows bimodal nascent rotational distributions of OH products with low- and high-N″ components with a ratio of 2.4:1. No spin-orbit propensities were observed, and the averaged ratios of Π(A')/Π(A″) were determined to be 1.66 ± 0.27. On the basis of computations at the CBS-QB3 theory level and comparison with prior theory, the microscopic mechanisms responsible for the nascent populations can be understood in terms of two competing dynamical pathways: a direct abstraction process in the low-N″ regime as the major pathway and an addition-complex forming process in the high-N″ regime as the minor pathway. Particularly, during the bond cleavage process of the weakly bound van der Waals complex C2H2—OH, the characteristic pathway from the low dihedral-angle geometry was consistent with the observed preferential population of the Π(A') component in the nascent OH products. A molecular-level discussion of the reactivity, mechanism, and dynamical features of the title reaction are presented together with a comparison to gas-phase oxidation reactions of a series of prototypical hydrocarbon radicals.

Electrochemical incineration of wastes

NASA Technical Reports Server (NTRS)

Kaba, L.; Hitchens, G. D.; Bockris, J. O'M.

1989-01-01

A low temperature electrolysis process has been developed for the treatment of solid waste material and urine. Experiments are described in which organic materials are oxidized directly at the surface of an electrode. Also, hypochlorite is generated electrochemically from chloride component of urine. Hypochlorite can act as a strong oxidizing agent in solution. The oxidation takes place at 30-60 C and the gaseous products from the anodic reaction are carbon dioxide, nitrogen, oxygen. Hydrogen is formed at the cathode. Carbon monoxide, and nitrogen oxides and methane were not detected in the off gases. Chlorine was evolved at the anode in relatively low amounts.

The Use of Combustion Reactions for Processing Mineral Raw Materials: Metallothermy and Self-propagating High-temperature Synthesis (Review)

NASA Astrophysics Data System (ADS)

Urakaev, Farit Kh.; Akmalaev, Kenzhebek A.; Orynbekov, Eljan S.; Balgysheva, Beykut D.; Zharlykasimova, Dinar N.

2016-02-01

The use of metallothermy (MT) and self-propagating high-temperature synthesis (SHS) is considered for processing different geological and technogenic materials. Traditional MT and SHS processes for production of various metals and nonmetal materials are widely known. Another rapidly developing direction is that connected with the use of ores, concentrates, minerals, and technogenic waste products as one of the components of a thermite mixture, both for the treatment of mineral raw by means of MT or SHS resulting in semi-products and for technological, analytical, and ecological purposes.

A Review on Recent Advances in the Application of Nanocatalysts in A3 Coupling Reactions.

PubMed

Nasrollahzadeh, Mahmoud; Sajjadi, Mohaddeseh; Ghorbannezhad, Fatemeh; Sajadi, S Mohammad

2018-03-14

A 3 coupling is one of the few transition-metal catalyzed carbon-carbon bond forming reactions that have been established as a most direct, efficient and atom-economical synthetic approach to afford propargylamine derivatives using various catalysts. A large number of nanosized heterogeneous catalysts for three-component coupling reactions between an aldehyde, an amine, and a terminal alkyne have been popularly introduced as an A 3 coupling in the last decade. The coupling product has found a broad application as a key intermediate for a variety of heterocyclic useful compounds and numerous biologically active molecules such as β-lactams, conformationally restricted peptides, isosteres, herbicides, fungicides, indolizines, pyrroles, quinolines and therapeutic drug molecules. This review aims to give an overview of the current progress made towards the preparation and application of various nanocatalysts-catalyzed A 3 coupling transformations for the synthesis of propargylamines from 2007 to 2017. Several nanocatalysts based on metal and metal oxide nanoparticles (NPs) such as copper, gold, silver, iron, nickel, cobalt and zinc have successfully been employed in A 3 coupling reactions. Besides, core-shells NPs, polymers, complexes, graphenes, metal-organic frameworks and ionic liquids have also been used in these reactions. Abundant examples have been given in this area. Different aspects of the reactions, disparate methods of preparation of nanocatalysts, characterization and their reusability have been perused. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tangled nonlinear driven chain reactions of all optical singularities

NASA Astrophysics Data System (ADS)

Vasil'ev, V. I.; Soskin, M. S.

2012-03-01

Dynamics of polarization optical singularities chain reactions in generic elliptically polarized speckle fields created in photorefractive crystal LiNbO3 was investigated in details Induced speckle field develops in the tens of minutes scale due to photorefractive 'optical damage effect' induced by incident beam of He-Ne laser. It was shown that polarization singularities develop through topological chain reactions of developing speckle fields driven by photorefractive nonlinearities induced by incident laser beam. All optical singularities (C points, optical vortices, optical diabolos,) are defined by instantaneous topological structure of the output wavefront and are tangled by singular optics lows. Therefore, they have develop in tangled way by six topological chain reactions driven by nonlinear processes in used nonlinear medium (photorefractive LiNbO3:Fe in our case): C-points and optical diabolos for right (left) polarized components domains with orthogonally left (right) polarized optical vortices underlying them. All elements of chain reactions consist from loop and chain links when nucleated singularities annihilated directly or with alien singularities in 1:9 ratio. The topological reason of statistics was established by low probability of far enough separation of born singularities pair from existing neighbor singularities during loop trajectories. Topology of developing speckle field was measured and analyzed by dynamic stokes polarimetry with few seconds' resolution. The hierarchy of singularities govern scenario of tangled chain reactions was defined. The useful space-time data about peculiarities of optical damage evolution were obtained from existence and parameters of 'islands of stability' in developing speckle fields.

Reaction time in ankle movements: a diffusion model analysis

PubMed Central

Michmizos, Konstantinos P.; Krebs, Hermano Igo

2015-01-01

Reaction time (RT) is one of the most commonly used measures of neurological function and dysfunction. Despite the extensive studies on it, no study has ever examined the RT in the ankle. Twenty-two subjects were recruited to perform simple, 2- and 4-choice RT tasks by visually guiding a cursor inside a rectangular target with their ankle. RT did not change with spatial accuracy constraints imposed by different target widths in the direction of the movement. RT increased as a linear function of potential target stimuli, as would be predicted by Hick–Hyman law. Although the slopes of the regressions were similar, the intercept in dorsal–plantar (DP) direction was significantly smaller than the intercept in inversion–eversion (IE) direction. To explain this difference, we used a hierarchical Bayesian estimation of the Ratcliff's (Psychol Rev 85:59, 1978) diffusion model parameters and divided processing time into cognitive components. The model gave a good account of RTs, their distribution and accuracy values, and hence provided a testimony that the non-decision processing time (overlap of posterior distributions between DP and IE < 0.045), the boundary separation (overlap of the posterior distributions < 0.1) and the evidence accumulation rate (overlap of the posterior distributions < 0.01) components of the RT accounted for the intercept difference between DP and IE. The model also proposed that there was no systematic change in non-decision processing time or drift rate when spatial accuracy constraints were altered. The results were in agreement with the memory drum hypothesis and could be further justified neurophysiologically by the larger innervation of the muscles controlling DP movements. This study might contribute to assessing deficits in sensorimotor control of the ankle and enlighten a possible target for correction in the framework of our on-going effort to develop robotic therapeutic interventions to the ankle of children with cerebral palsy. PMID:25030966

Genetic evaluations for growth heat tolerance in Angus cattle.

PubMed

Bradford, H L; Fragomeni, B O; Bertrand, J K; Lourenco, D A L; Misztal, I

2016-10-01

The objectives were to assess the impact of heat stress and to develop a model for genetic evaluation of growth heat tolerance in Angus cattle. The American Angus Association provided weaning weight (WW) and yearling weight (YW) data, and records from the Upper South region were used because of the hot climatic conditions. Heat stress was characterized by a weaning (yearling) heat load function defined as the mean temperature-humidity index (THI) units greater than 75 (70) for 30 (150) d prior to the weigh date. Therefore, a weaning (yearling) heat load of 5 units corresponded to 80 (75) for the corresponding period prior to the weigh date. For all analyses, 82,669 WW and 69,040 YW were used with 3 ancestral generations in the pedigree. Univariate models were a proxy for the Angus growth evaluation, and reaction norms using 2 B-splines for heat load were fit separately for weaning and yearling heat loads. For both models, random effects included direct genetic, maternal genetic, maternal permanent environment (WW only), and residual. Fixed effects included a linear age covariate, age-of-dam class (WW only), and contemporary group for both models and fixed regressions on the B-splines in the reaction norm. Direct genetic correlations for WW were strong for modest heat load differences but decreased to less than 0.50 for large differences. Reranking of proven sires occurred for only WW direct effects for the reaction norms with extreme heat load differences. Conversely, YW results indicated little effect of heat stress on genetic merit. Therefore, weaning heat tolerance was a better candidate for developing selection tools. Maternal heritabilities were consistent across heat loads, and maternal genetic correlations were greater than 0.90 for nearly all heat load combinations. No evidence existed for a genotype × environment interaction for the maternal component of growth. Overall, some evidence exists for phenotypic plasticity for the direct genetic effects of WW, but traditional national cattle evaluations are likely adequately ranking sires for nonextreme environmental conditions.

Synthesis of unnatural amino acids via microwave-assisted regio-selective one-pot multi-component reactions of sulfamidates

EPA Science Inventory

Synthesis of triazole-based unnatural amino acids, triazole bisaminoacids and β-amino triazole has been described via stereo and regioselective one-pot multi-component reaction of sulfamidates, sodium azide, and alkynes under MW irradiation conditions. The developed method is app...

Cambium

NASA Technical Reports Server (NTRS)

Savidge, Rodney

2009-01-01

The Cambium investigation is one in a pair of investigations which utilizes the Advanced Biological Research System (ABRS). Cambium seeks definitive evidence that gravity has a direct effect on cambial cells (cells located under the inner bark where secondary growth occurs) in willow, Salix babylonica. The Cambium investigation uses willow plants flown on the International Space Station to better understand the fundamental processes by which plants produce cellulose and lignin, the two main structural materials found in plant matter. On Earth, the nature of wood within tree stems varies depending on position, and that within-tree variation includes differences in cell types and chemistry including lignin and cellulose, two major components of wood influencing wood strength, usefulness and carbon content. Reaction wood is an extreme example of such variation, and it is believed that reaction wood develops as a reaction to the influence of gravity. For the Cambium experiment, young willow plants will be launched to the ISS where their stems will be looped in an attempt to induce reaction wood formation. After on-orbit growth, the plants will be preserved and returned to Earth for analysis. Understanding the role of gravity in wood formation is expected to enable wiser management of forests for carbon sequestration as well as better utilization of trees for wood products. Detailed Research Description: The Cambium experiment will provide an understanding of physiological processes such as gene expression, metabolism and general plant development that are affected in plant systems exposed to space flight. Cambium seeks definitive evidence that gravity has a direct effect on the cambial cells (cells located under the inner bark where secondary growth occurs) that contribute to xylogenesis (reaction wood formation) in willow plants, Salix babylonica. Tension wood fibers differentiate on the upper sides of stems when the stem is altered from its normal (vertical) growth position by looping. This reaction wood response does not occur if the orientation of the plant stem with respect to gravity is not altered. If a localized zone of tension wood should be formed in looped stems under microgravity conditions, this would be the first conclusive evidence that gravity is not required. On the other hand, if a zone of tension wood is not produced in looped stems (subjected to tension on one side, compression on the other) in microgravity, this would be the first definitive evidence that gravity has a direct effect on the cambial cells which contribute to reaction wood formation. Following return to Earth the plants will be analyzed by microscopy and chemical methods.

Ruthenium-catalyzed alkylation of indoles with tertiary amines by oxidation of a sp3 C-H bond and Lewis acid catalysis.

PubMed

Wang, Ming-Zhong; Zhou, Cong-Ying; Wong, Man-Kin; Che, Chi-Ming

2010-05-17

Ruthenium porphyrins (particularly [Ru(2,6-Cl(2)tpp)CO]; tpp=tetraphenylporphinato) and RuCl(3) can act as oxidation and/or Lewis acid catalysts for direct C-3 alkylation of indoles, giving the desired products in high yields (up to 82% based on 60-95% substrate conversions). These ruthenium compounds catalyze oxidative coupling reactions of a wide variety of anilines and indoles bearing electron-withdrawing or electron-donating substituents with high regioselectivity when using tBuOOH as an oxidant, resulting in the alkylation of N-arylindoles to 3-{[(N-aryl-N-alkyl)amino]methyl}indoles (yield: up to 82%, conversion: up to 95%) and the alkylation of N-alkyl or N-H indoles to 3-[p-(dialkylamino)benzyl]indoles (yield: up to 73%, conversion: up to 92%). A tentative reaction mechanism involving two pathways is proposed: an iminium ion intermediate may be generated by oxidation of an sp(3) C-H bond of the alkylated aniline by an oxoruthenium species; this iminium ion could then either be trapped by an N-arylindole (pathway A) or converted to formaldehyde, allowing a subsequent three-component coupling reaction of the in situ generated formaldehyde with an N-alkylindole and an aniline in the presence of a Lewis acid catalyst (pathway B). The results of deuterium-labeling experiments are consistent with the alkylation of N-alkylindoles via pathway B. The relative reaction rates of [Ru(2,6-Cl(2)tpp)CO]-catalyzed oxidative coupling reactions of 4-X-substituted N,N-dimethylanilines with N-phenylindole (using tBuOOH as oxidant), determined through competition experiments, correlate linearly with the substituent constants sigma (R(2)=0.989), giving a rho value of -1.09. This rho value and the magnitudes of the intra- and intermolecular deuterium isotope effects (k(H)/k(D)) suggest that electron transfer most likely occurs during the initial stage of the oxidation of 4-X-substituted N,N-dimethylanilines. Ruthenium-catalyzed three-component reaction of N-alkyl/N-H indoles, paraformaldehyde, and anilines gave 3-[p-(dialkylamino)benzyl]indoles in up to 82% yield (conversion: up to 95%).

Interactions between Therapeutic Proteins and Acrylic Acid Leachable.

PubMed

Liu, Dengfeng; Nashed-Samuel, Yasser; Bondarenko, Pavel V; Brems, David N; Ren, Da

2012-01-01

Leachables are chemical compounds that migrate from manufacturing equipment, primary containers and closure systems, and packaging components into biopharmaceutical and pharmaceutical products. Acrylic acid (at concentration around 5 μg/mL) was detected as leachable in syringes from one of the potential vendors (X syringes). In order to evaluate the potential impact of acrylic acid on therapeutic proteins, an IgG 2 molecule was filled into a sterilized X syringe and then incubated at 45 °C for 45 days in a pH 5 acetate buffer. We discovered that acrylic acid can interact with proteins at three different sites: (1) the lysine side chain, (2) the N-terminus, and (3) the histidine side chain, by the Michael reaction. In this report, the direct interactions between acrylic acid leachable and a biopharmaceutical product were demonstrated and the reaction mechanism was proposed. Even thought a small amount (from 0.02% to 0.3%) of protein was found to be modified by acrylic acid, the modified protein can potentially be harmful due to the toxicity of acrylic acid. After being modified by acrylic acid, the properties of the therapeutic protein may change due to charge and hydrophobicity variations. Acrylic acid was detected to migrate from syringes (Vendor X) into a therapeutic protein solution (at a concentration around 5 μg/mL). In this study, we discovered that acrylic acid can modify proteins at three different sites: (1) the lysine side chain, 2) the N-terminus, and 3) the histidine side chain, by the Michael reaction. In this report, the direct interactions between acrylic acid leachable and a biopharmaceutical product were demonstrated and the reaction mechanism was proposed.

[Eczema and food allergy--is there a causal relationship?].

PubMed

Spiewak, Radosław

2013-01-01

In spite of popular beliefs, the relationship between eczema and food allergy still puzzles researchers and clinicians, which in part is due to the variety of mechanisms involved in various types of allergy. One has to realize the differences between hypersensitivity reactions to food proteins (allergens capable of initiating immediate hypersensitivity or immune complex reactions) and low-molecular weight compounds (haptens that may initiate cytotoxic reactions or delayed-type allergy). Hardly doubted is the role of IgE specific to food proteins in anaphylactic reactions and allergic urticaria. The involvement of food protein-specific IgE also is well-documented in protein contact dermatitis, with exposure to offending allergens occurring mainly through direct contact to the skin. In case of oral intake, protein allergens can provoke oral allergy syndrome or allergic reactions of esophageal mucosa, yet after arriving in the stomach they undergo hydrolytic digestion and loose antigenicity. The popular notion "food allergy causes eczema" was challenged by last decade's research suggesting that allergy to food proteins develops secondarily to eczema, and in the later course manifests as anaphylaxis or urticaria, not eczema. On the other hand, somewhat unnoticed remains the wide array of haptens present in food - be it natural components, food additives (dyes, aromas, preservatives, emulsifiers, etc.) or contaminations (e.g. pesticides, veterinary drugs). Haptens can be absorbed already through oral mucosa, they don't undergo digestion and are capable of provoking delayed-type hypersensitivity reactions strongly resembling atopic eczema. Induction of such reactions can be facilitated by cosmetics that frequently contain the same haptens as food.

Silicone-containing composition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohamed, Mustafa

A silicone-containing composition comprises the reaction product of a first component and an excess of an isocyanate component relative to the first component to form an isocyanated intermediary. The first component is selected from one of a polysiloxane and a silicone resin. The first component includes a carbon-bonded functional group selected from one of a hydroxyl group and an amine group. The isocyanate component is reactive with the carbon-bonded functional group of the first component. The isocyanated intermediary includes a plurality of isocyanate functional groups. The silicone-containing composition comprises the further reaction product of a second component, which is selectedmore » from the other of the polysiloxane and the silicone resin. The second component includes a plurality of carbon-bonded functional groups reactive with the isocyanate functional groups of the isocyanated intermediary for preparing the silicone-containing composition.« less

Identification of atomic-level mechanisms for gas-phase X- + CH3Y SN2 reactions by combined experiments and simulations.

PubMed

Xie, Jing; Otto, Rico; Mikosch, Jochen; Zhang, Jiaxu; Wester, Roland; Hase, William L

2014-10-21

For the traditional model of gas-phase X(-) + CH3Y SN2 reactions, C3v ion-dipole pre- and postreaction complexes X(-)---CH3Y and XCH3---Y(-), separated by a central barrier, are formed. Statistical intramolecular dynamics are assumed for these complexes, so that their unimolecular rate constants are given by RRKM theory. Both previous simulations and experiments have shown that the dynamics of these complexes are not statistical and of interest is how these nonstatistical dynamics affect the SN2 rate constant. This work also found there was a transition from an indirect, nonstatistical, complex forming mechanism, to a direct mechanism, as either the vibrational and/or relative translational energy of the reactants was increased. The current Account reviews recent collaborative studies involving molecular beam ion-imaging experiments and direct (on-the-fly) dynamics simulations of the SN2 reactions for which Cl(-), F(-), and OH(-) react with CH3I. Also considered are reactions of the microsolvated anions OH(-)(H2O) and OH(-)(H2O)2 with CH3I. These studies have provided a detailed understanding of the atomistic mechanisms for these SN2 reactions. Overall, the atomistic dynamics for the Cl(-) + CH3I SN2 reaction follows those found in previous studies. The reaction is indirect, complex forming at low reactant collision energies, and then there is a transition to direct reaction between 0.2 and 0.4 eV. The direct reaction may occur by rebound mechanism, in which the ClCH3 product rebounds backward from the I(-) product or a stripping mechanism in which Cl(-) strips CH3 from the I atom and scatters in the forward direction. A similar indirect to direct mechanistic transition was observed in previous work for the Cl(-) + CH3Cl and Cl(-) + CH3Br SN2 reactions. At the high collision energy of 1.9 eV, a new indirect mechanism, called the roundabout, was discovered. For the F(-) + CH3I reaction, there is not a transition from indirect to direct reaction as Erel is increased. The indirect mechanism, with prereaction complex formation, is important at all the Erel investigated, contributing up ∼60% of the reaction. The remaining direct reaction occurs by the rebound and stripping mechanisms. Though the potential energy curve for the OH(-) + CH3I reaction is similar to that for F(-) + CH3I, the two reactions have different dynamics. They are akin, in that for both there is not a transition from an indirect to direct reaction. However, for F(-) + CH3I indirect reaction dominates at all Erel, but it is less important for OH(-) + CH3I and becomes negligible as Erel is increased. Stripping is a minor channel for F(-) + CH3I, but accounts for more than 60% of the OH(-) + CH3I reaction at high Erel. Adding one or two H2O molecules to OH(-) alters the reaction dynamics from that for unsolvated OH(-). Adding one H2O molecule enhances indirect reaction at low Erel, and changes the reaction mechanism from primarily stripping to rebound at high Erel. With two H2O molecules the dynamics is indirect and isotropic at all collision energies.

A centrifugal direct recombinase polymerase amplification (direct-RPA) microdevice for multiplex and real-time identification of food poisoning bacteria.

PubMed

Choi, Goro; Jung, Jae Hwan; Park, Byung Hyun; Oh, Seung Jun; Seo, Ji Hyun; Choi, Jong Seob; Kim, Do Hyun; Seo, Tae Seok

2016-06-21

In this study, we developed a centrifugal direct recombinase polymerase amplification (direct-RPA) microdevice for multiplex and real-time identification of food poisoning bacteria contaminated milk samples. The microdevice was designed to contain identical triplicate functional units and each unit has four reaction chambers, thereby making it possible to perform twelve direct-RPA reactions simultaneously. The integrated microdevice consisted of two layers: RPA reagents were injected in the top layer, while spiked milk samples with food poisoning bacteria were loaded into sample reservoirs in the bottom layer. For multiplex bacterial detection, the target gene-specific primers and probes were dried in each reaction chamber. The introduced samples and reagents could be equally aliquoted and dispensed into each reaction chamber by centrifugal force, and then the multiplex direct-RPA reaction was executed. The target genes of bacteria spiked in milk could be amplified at 39 °C without a DNA extraction step by using the direct-RPA cocktails, which were a combination of a direct PCR buffer and RPA enzymes. As the target gene amplification proceeded, the increased fluorescence signals coming from the reaction chambers were recorded in real-time at an interval of 2 min. The entire process, including the sample distribution, the direct-RPA reaction, and the real-time analysis, was accomplished with a custom-made portable genetic analyzer and a miniaturized optical detector. Monoplex, duplex, and triplex food poisoning bacteria (Salmonella enterica, Escherichia coli O157:H7, and Vibrio parahaemolyticus) detection was successfully performed with a detection sensitivity of 4 cells per 3.2 μL of milk samples within 30 min. By implementing the direct-PRA on the miniaturized centrifugal microsystem, the on-site food poisoning bacteria analysis would be feasible with high speed, sensitivity, and multiplicity.

Complex formation between the protein components of methane monooxygenase from Methylosinus trichosporium OB3b. Identification of sites of component interaction.

PubMed

Fox, B G; Liu, Y; Dege, J E; Lipscomb, J D

1991-01-05

Kinetic, spectroscopic, and chemical evidence for the formation of specific catalytically essential complexes between the three protein components of the soluble form of methane monooxygenase from Methylosinus trichosporium OB3b is reported. The effects of the concentrations of the reductase and component B on the hydroxylation activity of the reconstituted enzyme system has been numerically simulated based on a kinetic model which assumes formation of multiple high affinity complexes with the hydroxylase component during catalysis. The formation of several of these complexes has been directly demonstrated. By using EPR spectroscopy, the binding of approximately 2 mol of component B/mol of hydroxylase (subunit structure (alpha beta gamma)2) is shown to significantly change the electronic environment of the mu-(H/R)-oxo-bridged binuclear iron cluster of the hydroxylase in both the mixed valent (Fe(II).Fe(III)) and fully reduced (Fe(II).Fe(II)) states. Protein-protein complexes between the reductase and component B as well as between the reductase and hydroxylase have been shown to form by monitoring quenching of the tryptophan fluorescence spectrum of either the component B (KD approximately 0.4 microM) or hydroxylase (two binding sites, KDa approximately 10 nM, KDb approximately 8 microM). The observed KD values are in agreement with the best fit values from the kinetic simulation. Through the use of the covalent zero length cross-linking reagent 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC), the binding sites of the component B and reductase were shown to be on the hydroxylase alpha and beta subunits, respectively. The alpha and beta subunits of the hydroxylase are cross-linked by EDC suggesting that they are juxtaposed. EDC also caused the rapid loss of the ability of the monomeric component B to stimulate the hydroxylation reaction suggesting that cross-linking of reactive groups on the protein surface had occurred. This effect was inhibited by the presence of hydroxylase and was accompanied by a loss of the ability of the component B to bind to the hydroxylase. Thus, formation of a component B-hydroxylase complex is apparently required for effective catalysis linked to NADH oxidation. When present in concentrations greater than required to saturate the initial hydroxylase complex, component B inhibited both the rate of the enzymic reaction and the cross-linking of the reductase to the hydroxylase. This suggests that a second complex involving component B can form that negatively regulates catalysis by preventing formation of the reductase-hydroxylase complex.

The revision of the European blood directives: A major challenge for transfusion medicine.

PubMed

Folléa, G; Aranko, K

2015-08-01

Using both patient-focused and donor-focused perspectives, to review the current EU blood directives, in order to derive proposals, in principle, for what should evolve during the revision process of these directives. Review of the EU blood directives in the light of scientific literature, related reports from the Directorate General Health and Consumers (DG SANTÉ), and from the Council of Europe (CoE). The analyses led us to present the main following proposals: developing voluntary unpaid donations: the directives should consider taking into consideration ethically acceptable forms of compensation consistent with altruistic donation (including plasma donations for fractionation); current expertise: more extensive utilization of the expertise of blood establishments and their consultants should be considered; donor selection: an evidence-based approach for basing donor deferral criteria on sound scientific evidence should be promoted; donor reactions: measures to prevent donor reactions and to make donations safer for the donors should also be included; quality control: The quality control requirements should relate to the Council of Europe Blood Guide specifications: these should become minimum standards (as is the case with monographs of the European Pharmacopeia), facilitating regular update of blood component lists and related specifications and compliance with the specifications; haemovigilance: because of reporting difficulties (e.g. lack of number of blood products transfused), the effectiveness of haemovigilance has so far been limited. This should lead appropriate bodies to investigate alternative or complementary ways to help improve patient safety, taking into consideration, in principle, patient blood management and the appropriate use of blood products. Furthermore, donor vigilance, which is still absent from the current directive should be included in a revised directive. These proposals for revising the current EU blood directives (if taken into account and given appropriate regulatory formulation) should help to optimize patient safety and donor care, progress the compliance with the ethical principles for donors and improve the efficiency of the healthcare systems dedicated to transfusion medicine. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Allergic transfusion reactions from blood components donated by IgA-deficient donors with and without anti-IgA: a comparative retrospective study.

PubMed

Robitaille, N; Delage, G; Long, A; Thibault, L; Robillard, P

2010-08-01

IgA deficiency is common (1/500) and up to 40% of affected individuals will develop anti-IgA. A few studies suggested that passive transfusion of anti-IgA was not associated with an increased risk of allergic reactions. This study was designed to assess the safety of transfusing blood components containing anti-IgA. IgA-deficient blood donors with and without anti-IgA were identified from Héma-Québec's (HQ) computerized database. IgA deficiency was confirmed by an ELISA method and the presence of anti-IgA by a passive hemagglutination assay. Blood donations from IgA-deficient donors issued to hospitals between March 1999 and December 2004 were retrieved. Medical charts of recipients were reviewed for the occurrence of a suspected transfusion reaction. Presence and nature of transfusion reactions were assessed blindly by an adjudicating committee. A total of 323 IgA-deficient blood products were issued by HQ to 55 hospitals. Of these, 48 agreed to participate [315 blood products (97.5%)]. A total of 272 products were transfused: 174 contained anti-IgA, and 98 did not. Only two minor allergic reactions occurred in each group. Incidence of allergic reactions was 1.15% in the anti-IgA group and 2.04% in the group without anti-IgA (P = 0.91). There was no anaphylactic reaction in either group. This study indicates that the proportion of allergic reactions does not appear to be greater in recipients of blood components containing anti-IgA compared to recipients of non-anti-IgA-containing components. Allowing donations from IgA-deficient donors with anti-IgA may therefore be contemplated.

Divergent reaction pathways for one-pot, three-component synthesis of novel 4H-pyrano[3,2-h]quinolines under ultrasound irradiation.

PubMed

Al-Bogami, Abdullah S; Saleh, Tamer S; Zayed, Ehab M

2013-09-01

The present paper deal with the multi-component condensation of 8-hydroxy quinoline, aromatic aldehydes, and sulfone derivatives catalyzed by p-toluenesulfonic acid for the synthesis of a series of 4H-pyrano[3,2-h]quinoline derivatives in ethanol under ultrasonic irradiations. We provide a series of quinoline derivatives containing sulfone moiety interesting for biological screening tests. The reactions were carried out under both conventional and ultrasonic irradiation conditions. In general, improvement in rates and yields were observed when reactions were carried out under sonication compared with classical silent conditions. Also, also, sonochemical reaction give different reaction pathway other than silent reaction. These remarkable effects appeared in sonicated reactions can be reasonably interpreted in terms of acoustic cavitation phenomenon. Structures of the products were established on analytical and spectral data. Copyright © 2013 Elsevier B.V. All rights reserved.

Can Carbamates Undergo Radical Oxidation in the Soil Environment? A Case Study on Carbaryl and Carbofuran.

PubMed

Ćwieląg-Piasecka, Irmina; Witwicki, Maciej; Jerzykiewicz, Maria; Jezierska, Julia

2017-12-19

Radical oxidation of carbamate insecticides, namely carbaryl and carbofuran, was investigated with spectroscopic (electron paramagnetic resonance [EPR] and UV-vis) and theoretical (density functional theory [DFT] and ab initio orbital-optimized spin-component scaled MP2 [OO-SCS-MP2]) methods. The two carbamates were subjected to reaction with • OH, persistent DPPH • and galvinoxyl radical, as well as indigenous radicals of humic acids. The influence of fulvic acids on carbamate oxidation was also tested. The results obtained with EPR and UV-vis spectroscopy indicate that carbamates can undergo direct reactions with various radical species, oxidizing themselves into radicals in the process. Hence, they are prone to participate in the prolongation step of the radical chain reactions occurring in the soil environment. Theoretical calculations revealed that from the thermodynamic point of view hydrogen atom transfer is the preferred mechanism in the reactions of the two carbamates with the radicals. The activity of carbofuran was determined experimentally (using pseudo-first-order kinetics) and theoretically to be noticeably higher in comparison with carbaryl and comparable with gallic acid. The findings of this study suggest that the radicals present in soil can play an important role in natural remediation mechanisms of carbamates.

Emitted vibration measurement device and method

NASA Astrophysics Data System (ADS)

Gisler, G. L.

1986-10-01

This invention is directed to a method and apparatus for measuring emitted vibrational forces produced by a reaction wheel assembly due to imbalances, misalignment, bearing defects and the like. The apparatus includes a low mass carriage supported on a large mass base. The carriage is in the form of an octagonal frame having an opening which is adapted for receiving the reaction wheel assembly supported thereon by means of a mounting ring. The carriage is supported on the base by means of air bearings which support the carriage in a generally frictionless manner when supplied with compressed air from a source. A plurality of carriage brackets and a plurality of base blocks provided for physical coupling of the base and carriage. The sensing axes of the load cells are arranged generally parallel to the base and connected between the base and carriage such that all of the vibrational forces emitted by the reaction wheel assembly are effectively transmitted through the sensing axes of the load cells. In this manner, a highly reliable and accurate measurment of the vibrational forces of the reaction wheel assembly can be had. The output signals from the load cells are subjected to a dynamical analyzer which analyzes and identifies the rotor and spin bearing components which are causing the vibrational forces.

The redox-Mannich reaction.

PubMed

Chen, Weijie; Seidel, Daniel

2014-06-06

A complement to the classic three-component Mannich reaction, the redox-Mannich reaction, utilizes the same starting materials but incorporates an isomerization step that enables the facile preparation of ring-substituted β-amino ketones. Reactions occur under relatively mild conditions and are facilitated by benzoic acid.

Synthesis of isocoumarins through three-component couplings of arynes, terminal alkynes, and carbon dioxide catalyzed by an NHC-copper complex.

PubMed

Yoo, Woo-Jin; Nguyen, Thanh V Q; Kobayashi, Shū

2014-09-15

A copper-catalyzed multicomponent coupling reaction between in situ generated ortho-arynes, terminal alkynes, and carbon dioxide was developed to access isocoumarins in moderate to good yields. The key to this CO2-incorporating reaction was the use of a versatile N-heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three-component reaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stereoselective Synthesis of Functionalized Bicyclic Scaffolds by Passerini 3-Center-2-Component Reactions of Cyclic Ketoacids.

PubMed

Cioc, Răzvan C; Estévez, Verónica; van der Niet, Daan J; Vande Velde, Christophe M L; Turrini, Nikolaus G; Hall, Mélanie; Faber, Kurt; Ruijter, Eelco; Orru, Romano V A

2017-03-03

We report the use of bifunctional starting materials (ketoacids) in a diastereoselective Passerini three-center-two-component reaction. Study of the reaction scope revealed the required structural features for stereoselectivity in the isocyanide addition. In this system, an interesting isomerization of the primary Passerini product - the α-carboxamido lactone - into an atypical product, an α-hydroxy imide, was found to occur under acidic conditions. Furthermore, enantioenriched Passerini products can be generated from an enantioenriched ketoacid obtained by chemoenzymatic synthesis.

Conservation of direct dynamics in sterically hindered SN2/E2 reactions.

PubMed

Carrascosa, Eduardo; Meyer, Jennifer; Michaelsen, Tim; Stei, Martin; Wester, Roland

2018-01-21

Nucleophilic substitution (S N 2) and base-induced elimination (E2), two indispensable reactions in organic synthesis, are commonly assumed to proceed under stereospecific conditions. Understanding the way in which the reactants pre-orient in these reactions, that is its stereodynamics, is essential in order to achieve a detailed atomistic picture and control over such processes. Using crossed beam velocity map imaging, we study the effect of steric hindrance in reactions of Cl - and CN - with increasingly methylated alkyl iodides by monitoring the product ion energy and scattering angle. For both attacking anions the rebound mechanism, indicative of a direct S N 2 pathway, is found to contribute to the reaction at high relative collision energies despite being increasingly hindered. An additional forward scattering mechanism, ascribed to a direct E2 reaction, also contributes at these energies. Inspection of the product energy distributions confirms the direct and fast character of both mechanisms as opposed to an indirect reaction mechanism which leads to statistical energy redistribution in the reaction complex. This work demonstrates that nonstatistical dynamics and energetics govern S N 2 and E2 pathways even in sterically hindered exchange reaction systems.

Conservation of direct dynamics in sterically hindered SN2/E2 reactions

PubMed Central

Carrascosa, Eduardo; Meyer, Jennifer; Michaelsen, Tim; Stei, Martin

2017-01-01

Nucleophilic substitution (SN2) and base-induced elimination (E2), two indispensable reactions in organic synthesis, are commonly assumed to proceed under stereospecific conditions. Understanding the way in which the reactants pre-orient in these reactions, that is its stereodynamics, is essential in order to achieve a detailed atomistic picture and control over such processes. Using crossed beam velocity map imaging, we study the effect of steric hindrance in reactions of Cl– and CN– with increasingly methylated alkyl iodides by monitoring the product ion energy and scattering angle. For both attacking anions the rebound mechanism, indicative of a direct SN2 pathway, is found to contribute to the reaction at high relative collision energies despite being increasingly hindered. An additional forward scattering mechanism, ascribed to a direct E2 reaction, also contributes at these energies. Inspection of the product energy distributions confirms the direct and fast character of both mechanisms as opposed to an indirect reaction mechanism which leads to statistical energy redistribution in the reaction complex. This work demonstrates that nonstatistical dynamics and energetics govern SN2 and E2 pathways even in sterically hindered exchange reaction systems. PMID:29629138

A novel three-component reaction for the synthesis of 1,3-benzoxazines in water.

PubMed

Rostami-Charati, Faramarz

2013-12-01

A simple and proficient method for the synthesis of 1,3-benzoxazine derivatives via three-component reaction of isocyanide and isoquinoline with 1-(6-hydroxy-2-isopropenyl-1-benzofuran-yl)-1-ethanone or 4-hydroxycumarine in water in the presence of piperidine at 70°C is reported.

Differentiating Motivational from Affective Influence of Performance-contingent Reward on Cognitive Control: The Wanting Component Enhances Both Proactive and Reactive Control.

PubMed

Chaillou, Anne-Clémence; Giersch, Anne; Hoonakker, Marc; Capa, Rémi L; Bonnefond, Anne

2017-04-01

Positive affect strongly modulates goal-directed behaviors and cognitive control mechanisms. It often results from the presence of a pleasant stimulus in the environment, whether that stimulus appears unpredictably or as a consequence of a particular behavior. The influence of positive affect linked to a random pleasant stimulus differs from the influence of positive affect resulting from performance-contingent pleasant stimuli. However, the mechanisms by which the performance contingency of pleasant stimuli modulates the influence of positive affect on cognitive control mechanisms have not been elucidated. Here, we tested the hypothesis that these differentiated effects are the consequence of the activation of the motivational "wanting" component specifically under performance contingency conditions. To that end, we directly compared the effects on cognitive control of pleasant stimuli (a monetary reward) attributed in a performance contingent manner, and of random pleasant stimuli (positive picture) not related to performance, during an AX-CPT task. Both proactive and reactive modes of control were increased specifically by performance contingency, as reflected by faster reaction times and larger amplitude of the CNV and P3a components. Our findings advance our understanding of the respective effects of affect and motivation, which is of special interest regarding alterations of emotion-motivation interaction found in several psychopathological disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

In-vitro effects of Thymus munbyanus essential oil and thymol on human sperm motility and function.

PubMed

Chikhoune, Amirouche; Stouvenel, Laurence; Iguer-Ouada, Mokrane; Hazzit, Mohamed; Schmitt, Alain; Lorès, Patrick; Wolf, Jean Philippe; Aissat, Kamel; Auger, Jacques; Vaiman, Daniel; Touré, Aminata

2015-09-01

Traditional medicine has been used worldwide for centuries to cure or prevent disease and for male or female contraception. Only a few studies have directly investigated the effects of herbal compounds on spermatozoa. In this study, essential oil from Thymus munbyanus was extracted and its effect on human spermatozoa in vitro was analysed. Gas chromatography and Gas chromatography-mass spectrometry analyses identified 64 components, accounting for 98.9% of the composition of the oil. The principal components were thymol (52.0%), γ-terpinene (11.0%), ρ-cymene (8.5%) and carvacrol (5.2%). Freshly ejaculated spermatozoa was exposed from control individuals to various doses of the essential oil for different time periods, and recorded the vitality, the mean motility, the movement characteristics (computer-aided sperm analysis), the morphology and the ability to undergo protein hyperphosphorylation and acrosomal reaction, which constitute two markers of sperm capacitation and fertilizing ability. In vitro, both the essential oil extracted from T. munbyanus and thymol, the principal compound present in this oil, impaired human sperm motility and its capacity to undergo hyperphosphorylation and acrosome reaction. These compounds may, therefore, be of interest in the field of reproductive biology, as potential anti-spermatic agents. Copyright © 2015 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

PhreeqcRM: A reaction module for transport simulators based on the geochemical model PHREEQC

USGS Publications Warehouse

Parkhurst, David L.; Wissmeier, Laurin

2015-01-01

PhreeqcRM is a geochemical reaction module designed specifically to perform equilibrium and kinetic reaction calculations for reactive transport simulators that use an operator-splitting approach. The basic function of the reaction module is to take component concentrations from the model cells of the transport simulator, run geochemical reactions, and return updated component concentrations to the transport simulator. If multicomponent diffusion is modeled (e.g., Nernst–Planck equation), then aqueous species concentrations can be used instead of component concentrations. The reaction capabilities are a complete implementation of the reaction capabilities of PHREEQC. In each cell, the reaction module maintains the composition of all of the reactants, which may include minerals, exchangers, surface complexers, gas phases, solid solutions, and user-defined kinetic reactants.PhreeqcRM assigns initial and boundary conditions for model cells based on standard PHREEQC input definitions (files or strings) of chemical compositions of solutions and reactants. Additional PhreeqcRM capabilities include methods to eliminate reaction calculations for inactive parts of a model domain, transfer concentrations and other model properties, and retrieve selected results. The module demonstrates good scalability for parallel processing by using multiprocessing with MPI (message passing interface) on distributed memory systems, and limited scalability using multithreading with OpenMP on shared memory systems. PhreeqcRM is written in C++, but interfaces allow methods to be called from C or Fortran. By using the PhreeqcRM reaction module, an existing multicomponent transport simulator can be extended to simulate a wide range of geochemical reactions. Results of the implementation of PhreeqcRM as the reaction engine for transport simulators PHAST and FEFLOW are shown by using an analytical solution and the reactive transport benchmark of MoMaS.

Catalyst-free activation of methylene chloride and alkynes by amines in a three-component coupling reaction to synthesize propargylamines.

PubMed

Rawat, Vikas S; Bathini, Thulasiram; Govardan, S; Sreedhar, Bojja

2014-09-14

Propargylamines are synthesized via metal-free activation of the C-halogen bond of dihalomethanes and the C-H bond of terminal alkynes in a three-component coupling without catalyst or additional base and under mild reaction conditions. The dihalomethanes are used both as solvents as well as precursors for the methylene fragment (C1) in the final product. The scope of the reaction and the influence of various reaction variables has been investigated. A plausible reaction mechanism is proposed and the involvement of various intermediates that can be generated in situ in the process is discussed. The metal-free conditions also make this protocol environmentally benign and atom economical.

Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

DOE PAGES

Jones, K. L.; Ahn, S.; Allmond, J. M.; ...

2015-01-01

Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, Nmore » = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn- 106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.« less

Contrasting influence of NADPH and a NADPH-regenerating system on the metabolism of carbonyl-containing compounds in hepatic microsomes.

PubMed

Mazur, Christopher S; Kenneke, John F; Goldsmith, Michael-Rock; Brown, Cather

2009-09-01

Carbonyl containing xenobiotics may be susceptible to NADPH-dependent cytochrome P450 (P450) and carbonyl-reduction reactions. In vitro hepatic microsome assays are routinely supplied NADPH either by direct addition of NADPH or via an NADPH-regenerating system (NRS). In contrast to oxidative P450 transformations, which occur on the periphery of a microsome vesicle, intraluminal carbonyl reduction depends on transport of cofactors across the endoplasmic reticulum (ER) membrane into the lumen. Glucose 6-phosphate, a natural cofactor and component of the NRS matrix, is readily transported across the ER membrane and facilitates intraluminal NADPH production, whereas direct addition of NADPH has limited access to the lumen. In this study, we compared the effects of direct addition of NADPH and use of an NRS on the P450-mediated transformation of propiconazole and 11 beta-hydroxysteroid dehydrogenase type 1 (HSD1) carbonyl reduction of cortisone and the xenobiotic triadimefon in hepatic microsomes. Our results demonstrate that the use of NADPH rather than NRS can underestimate the kinetic rates of intraluminal carbonyl reduction, whereas P450-mediated transformations were unaffected. Therefore, in vitro depletion rates measured for a carbonyl-containing xenobiotic susceptible to both intraluminal carbonyl reduction and P450 processes may not be properly assessed with direct addition of NADPH. In addition, we used in silico predictions as follows: 1) to show that 11 beta-HSD1 carbonyl reduction was energetically more favorable than oxidative P450 transformation; and 2) to calculate chemical binding score and the distance between the carbonyl group and the hydride to be transferred by NADPH to identify other 11 beta-HSD1 substrates for which reaction kinetics may be underestimated by direct addition of NADPH.

Lifetimes of bacteriochlorophyll fluorescence in Rhodopseudomonas viridis and Heliobacterium chlorum at low temperatures

NASA Technical Reports Server (NTRS)

Kleinherenbrink, F. A.; Cheng, P.; Amesz, J.; Blankenship, R. E.

1993-01-01

Fluorescence lifetimes of isolated membranes of Rhodopseudomonas viridis were measured in the temperature range of 77 K to 25 K. At room temperature, the main component of the fluorescence decay of bacteriochlorophyll (BChl) b had a time constant of 50 ps. In contrast to other purple bacteria, the emission at low temperature was spectrally homogeneous and showed essentially single lifetimes of 140 ps at 77 K and 180 ps at 25 K, with the primary electron donor in the oxidized state. Taking into account the relative fluorescence yields with open and closed reaction centers, we arrive at numbers of 125 ps and 215 ps, respectively, for open reaction centers. These numbers are significantly smaller than expected on the basis of measurements of the efficiency of charge separation, perhaps suggesting that the excitation decay in the absence of reaction centers is considerably faster at low temperature than at room temperature. At least four different spectral components with different lifetimes were observed at 25 K in the emission of Heliobacterium chlorum, a short-wavelength component of about 30 ps and three longer-wavelength components of about 100 ps, 300 ps, and 900 ps. This indicates a strong heterogeneity in the emitting pigment, BChl g-808. The component with the shortest lifetime does not appear to be affected by the redox state of the reaction center and might reflect energy transfer to BChl g species which are connected to the reaction center.

Selective chemical detection by energy modulation of sensors

DOEpatents

Stetter, J.R.; Otagawa, T.

1991-09-10

A portable instrument for use in the field in detecting, identifying, and quantifying a component of a sampled fluid includes a sensor which chemically reacts with the component of interest or a derivative thereof, an electrical heating filament for heating the sample before it is applied to the sensor, and modulator for continuously varying the temperature of the filament (and hence the reaction rate) between two values sufficient to produce the chemical reaction. In response to this thermal modulation, the sensor produces a modulated output signal, the modulation of which is a function of the activation energy of the chemical reaction, which activation energy is specific to the particular component of interest and its concentration. Microprocessor which compares the modulated output signal with standard responses for a plurality of components to identify and quantify the particular component of interest. In particular, the concentration of the component of interest is proportional to the amplitude of the modulated output signal, while the identifying activation output energy of the chemical interaction indicative of that component is proportional to a normalized parameter equal to the peak-to-peak amplitude divided by the height of the upper peaks above a base line signal level. 5 figures.

Selective chemical detection by energy modulation of sensors

DOEpatents

Stetter, Joseph R.; Otagawa, Takaaki

1991-01-01

A portable instrument for use in the field in detecting, identifying, and quantifying a component of a sampled fluid includes a sensor which chemically reacts with the component of interest or a derivative thereof, an electrical heating filament for heating the sample before it is applied to the sensor, and modulator for continuously varying the temperature of the filament (and hence the reaction rate) between two values sufficient to produce the chemical reaction. In response to this thermal modulation, the sensor produces a modulated output signal, the modulation of which is a function of the activation energy of the chemical reaction, which activation energy is specific to the particular component of interest and its concentration. Microprocessor which compares the modulated output signal with standard responses for a plurality of components to identify and quantify the particular component of interest. In particular, the concentration of the component of interest is proportional to the amplitude of the modulated output signal, while the identifying activation output energy of the chemical interaction indicative of that component is proportional to a normalized parameter equal to the peak-to-peak amplitude divided by the height of the upper peaks above a base line signal level.

Novel multicomponent reaction for the combinatorial synthesis of 2-imidazolines.

PubMed

Bon, Robin S; Hong, Chongen; Bouma, Marinus J; Schmitz, Rob F; de Kanter, Frans J J; Lutz, Martin; Spek, Anthony L; Orru, Romano V A

2003-10-02

[reaction: see text] The three-component condensation between an amine, an aldehyde, and an alpha-acidic isocyanide efficiently provides substituted 2-imidazolines in a one-pot reaction under mild conditions.

Formation of high-molecular-weight compounds via the heterogeneous reactions of gaseous C8-C10 n-aldehydes in the presence of atmospheric aerosol components

NASA Astrophysics Data System (ADS)

Han, Yuemei; Kawamura, Kimitaka; Chen, Qingcai; Mochida, Michihiro

2016-02-01

A laboratory study on the heterogeneous reactions of straight-chain aldehydes was performed by exposing n-octanal, nonanal, and decanal vapors to ambient aerosol particles. The aerosol and blank filters were extracted using methanol. The extracts were nebulized and the resulting compositions were examined using a high-resolution time-of-flight aerosol mass spectrometer. The mass spectral analysis showed that the exposures of the aldehydes to aerosol samples increased the peak intensities in the high mass range. The peaks in the mass spectra of the aerosol samples after exposure to different aldehydes were characterized by a homologous series of peak shifts due to the addition of multiple CH2 units. This result is explained by the formation of high-molecular-weight (HMW) compounds that contain single or multiple aldehyde moieties. The HMW fragment peaks for the blank filters exposed to n-aldehydes were relatively weak, indicating an important contribution from the ambient aerosol components to the formation of the HMW compounds. Among the factors affecting the overall interaction of aldehydes with atmospheric aerosol components, gas phase diffusion possibly limited the reactions under the studied conditions; therefore, their occurrence to a similar degree in the atmosphere is not ruled out, at least for the reactions involving n-nonanal and decanal. The major formation pathways for the observed HMW products may be the self-reactions of n-aldehydes mediated by atmospheric aerosol components and the reactions of n-aldehydes with organic aerosol components. The observed formation of HMW compounds encourages further investigations into their effects on the aerosol properties as well as the organic aerosol mass in the atmosphere.

Three-Component Reactions of Diazoesters, Aldehydes, and Imines Using a Dual Catalytic System Consisting of a Rhodium(II) Complex and a Lewis Acid.

PubMed

Toda, Yasunori; Kaku, Wakatake; Tsuruoka, Makoto; Shinogaki, Sho; Abe, Tomoka; Kamiya, Hideaki; Kikuchi, Ayaka; Itoh, Kennosuke; Suga, Hiroyuki

2018-05-04

A dual catalytic system, dirhodium tetrapivalate/ytterbium(III) triflate, enables the three-component reactions of α-alkyl-α-diazoesters, aromatic aldehydes, and N-benzylidenebenzylamine derivatives to afford the corresponding β-amino alcohols in good yields after hydrolysis of the oxazolidine cycloadducts, whereas no β-amino alcohols are obtained in the absence of ytterbium(III) triflate. A similar dual catalytic system, dirhodium tetraacetate/ytterbium(III) triflate, is found to be effective in accelerating the reactions of α-aryl-α-diazoesters in high yields. Furthermore, the reactions using dimethyl diazomalonate are described.

Et3B-mediated radical-polar crossover reaction for single-step coupling of O,Te-acetal, α,β-unsaturated ketones, and aldehydes/ketones.

PubMed

Kamimura, Daigo; Urabe, Daisuke; Nagatomo, Masanori; Inoue, Masayuki

2013-10-04

Et3B-mediated three-component coupling reactions between O,Te-acetal, α,β-unsaturated ketones, and aldehydes/ketones were developed. Et3B promoted the generation of the potently reactive bridgehead radical from the O,Te-acetal of the trioxaadamantane structure and converted the α-carbonyl radical of the resultant two-component adduct to the boron enolate, which then underwent a stereoselective aldol reaction with the aldehyde/ketone. This powerful, yet mild, radical-polar crossover reaction efficiently connected the hindered linkages between the three units and selectively introduced three new stereocenters.

Signalling Network Construction for Modelling Plant Defence Response

PubMed Central

Miljkovic, Dragana; Stare, Tjaša; Mozetič, Igor; Podpečan, Vid; Petek, Marko; Witek, Kamil; Dermastia, Marina; Lavrač, Nada; Gruden, Kristina

2012-01-01

Plant defence signalling response against various pathogens, including viruses, is a complex phenomenon. In resistant interaction a plant cell perceives the pathogen signal, transduces it within the cell and performs a reprogramming of the cell metabolism leading to the pathogen replication arrest. This work focuses on signalling pathways crucial for the plant defence response, i.e., the salicylic acid, jasmonic acid and ethylene signal transduction pathways, in the Arabidopsis thaliana model plant. The initial signalling network topology was constructed manually by defining the representation formalism, encoding the information from public databases and literature, and composing a pathway diagram. The manually constructed network structure consists of 175 components and 387 reactions. In order to complement the network topology with possibly missing relations, a new approach to automated information extraction from biological literature was developed. This approach, named Bio3graph, allows for automated extraction of biological relations from the literature, resulting in a set of (component1, reaction, component2) triplets and composing a graph structure which can be visualised, compared to the manually constructed topology and examined by the experts. Using a plant defence response vocabulary of components and reaction types, Bio3graph was applied to a set of 9,586 relevant full text articles, resulting in 137 newly detected reactions between the components. Finally, the manually constructed topology and the new reactions were merged to form a network structure consisting of 175 components and 524 reactions. The resulting pathway diagram of plant defence signalling represents a valuable source for further computational modelling and interpretation of omics data. The developed Bio3graph approach, implemented as an executable language processing and graph visualisation workflow, is publically available at http://ropot.ijs.si/bio3graph/and can be utilised for modelling other biological systems, given that an adequate vocabulary is provided. PMID:23272172

Reaction mechanism and reaction coordinates from the viewpoint of energy flow

PubMed Central

2016-01-01

Reaction coordinates are of central importance for correct understanding of reaction dynamics in complex systems, but their counter-intuitive nature made it a daunting challenge to identify them. Starting from an energetic view of a reaction process as stochastic energy flows biased towards preferred channels, which we deemed the reaction coordinates, we developed a rigorous scheme for decomposing energy changes of a system, both potential and kinetic, into pairwise components. The pairwise energy flows between different coordinates provide a concrete statistical mechanical language for depicting reaction mechanisms. Application of this scheme to the C7eq → C7ax transition of the alanine dipeptide in vacuum revealed novel and intriguing mechanisms that eluded previous investigations of this well studied prototype system for biomolecular conformational dynamics. Using a cost function developed from the energy decomposition components by proper averaging over the transition path ensemble, we were able to identify signatures of the reaction coordinates of this system without requiring any input from human intuition. PMID:27004858

Reaction mechanism and reaction coordinates from the viewpoint of energy flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wenjin; Ma, Ao, E-mail: aoma@uic.edu

Reaction coordinates are of central importance for correct understanding of reaction dynamics in complex systems, but their counter-intuitive nature made it a daunting challenge to identify them. Starting from an energetic view of a reaction process as stochastic energy flows biased towards preferred channels, which we deemed the reaction coordinates, we developed a rigorous scheme for decomposing energy changes of a system, both potential and kinetic, into pairwise components. The pairwise energy flows between different coordinates provide a concrete statistical mechanical language for depicting reaction mechanisms. Application of this scheme to the C{sub 7eq} → C{sub 7ax} transition of themore » alanine dipeptide in vacuum revealed novel and intriguing mechanisms that eluded previous investigations of this well studied prototype system for biomolecular conformational dynamics. Using a cost function developed from the energy decomposition components by proper averaging over the transition path ensemble, we were able to identify signatures of the reaction coordinates of this system without requiring any input from human intuition.« less

Mass transfer constraints on the chemical evolution of an active hydrothermal system, Valles caldera, New Mexico

USGS Publications Warehouse

White, A.F.; Chuma, N.J.; Goff, F.

1992-01-01

Partial equilibrium conditions occur between fluids and secondary minerals in the Valles hydrothermal system, contained principally in the Tertiary rhyolitic Bandelier Tuff. The mass transfer processes are governed by reactive phase compositions, surface areas, water-rock ratios, reaction rates, and fluid residence times. Experimental dissolution of the vitric phase of the tuff was congruent with respect to Cl in the solid and produced reaction rates which obeyed a general Arrhenius release rate between 250 and 300??C. The 18O differences between reacted and unreacted rock and fluids, and mass balances calculations involving Cl in the glass phase, produced comparable water-rock ratios of unity, confirming the importance of irreversible reaction of the vitric tuff. A fluid residence time of approximately 2 ?? 103 years, determined from fluid reservoir volume and discharge rates, is less than 0.2% of the total age of the hydrothermal system and denotes a geochemically and isotopically open system. Mass transfer calculations generally replicated observed reservoir pH, Pco2, and PO2 conditions, cation concentrations, and the secondary mineral assemblage between 250 and 300??C. The only extraneous component required to maintain observed calcite saturation and high Pco2 pressures was carbon presumably derived from underlying Paleozoic limestones. Phase rule constraints indicate that Cl was the only incompatible aqueous component not controlled by mineral equilibrium. Concentrations of Cl in the reservoir directly reflect mass transport rates as evidenced by correlations between anomalously high Cl concentrations in the fluids and tuff in the Valles caldera relative to other hydrothermal systems in rhyolitic rocks. ?? 1992.

Significant impacts of heterogeneous reactions on the chemical composition and mixing state of dust particles: A case study during dust events over northern China

NASA Astrophysics Data System (ADS)

Wang, Zhe; Pan, Xiaole; Uno, Itsushi; Li, Jie; Wang, Zifa; Chen, Xueshun; Fu, Pingqing; Yang, Ting; Kobayashi, Hiroshi; Shimizu, Atsushi; Sugimoto, Nobuo; Yamamoto, Shigekazu

2017-06-01

The impact of heterogeneous reactions on the chemical components and mixing state of dust particles are investigated by observations and an air quality model over northern China between March 27, 2015 and April 2, 2015. Synergetic observations were conducted using a polarization optical particle counter (POPC), a depolarized two-wavelength Lidar and filter samples in Beijing. During this period, dust plume passed through Beijing on March 28, and flew back on March 29 because of synoptic weather changes. Mineral dust mixed with anthropogenic pollutants was simulated using the Nested Air Quality Prediction Modeling System (NAQPMS) to examine the role of heterogeneous processes on the dust. A comparison of observations shows that the NAQPMS successfully reproduces the time series of the vertical profile, particulate matter concentration, and chemical components of fine mode (diameter ≤ 2.5 μm) and coarse mode (2.5 μm < diameter ≤ 10 μm) particles. After considering the heterogeneous reactions, the simulated nitrate, ammonium, and sulfate are in better agreement with the observed values during this period. The modeling results with observations show that heterogeneous reactions are the major mechanisms producing nitrate reaching 19 μg/m3, and sulfate reaching 7 μg/m3, on coarse mode dust particles, which were almost 100% of the coarse mode nitrate and sulfate. The heterogeneous reactions are also important for fine mode secondary aerosols, for producing 17% of nitrate and 11% of sulfate on fine mode dust particles, with maximum mass concentrations of 6 μg/m3 and 4 μg/m3. In contrast, due to uptake of acid gases (e.g. HNO3 and SO2) by dust particles, the fine mode anthropogenic ammonium nitrate and ammonium sulfate decreased. As a result, the total fine mode nitrate decreased with a maximum of 14 μg/m3, while the total fine mode sulfate increased with a maximum of 2 μg/m3. Because of heterogeneous reactions, 15% of fine mode secondary inorganic aerosols and the entire coarse mode nitrate and sulfate were internally mixed with dust particles. The significant alterations of the chemical composition and mixing state of particles due to heterogeneous reactions are important for the direct and indirect climate effects of dust and anthropogenic aerosols.

A rare allergy to a polyether dental impression material.

PubMed

Mittermüller, Pauline; Szeimies, Rolf-Markus; Landthaler, Michael; Schmalz, Gottfried

2012-08-01

Polyether impression materials have been used in dentistry for more than 40 years. Allergic reactions to these materials such as reported in the 1970s ceased after replacement of a catalyst. Very recently, however, patients have started to report symptoms that suggest a new allergic reaction from polyether impression materials. Here, we report on the results of allergy testing with polyether impression materials as well as with its components. Eight patients with clinical symptoms of a contact allergy (swelling, redness or blisters) after exposure to a polyether impression material were subjected to patch tests, two of them additionally to a prick test. A further patient with atypical symptoms of an allergy (nausea and vomiting after contact with a polyether impression material in the oral cavity) but with a history of other allergic reaction was also patch tested. The prick tests showed no immediate reactions in the two patients tested. In the patch tests, all eight patients with typical clinical symptoms showed positive reactions to the mixed polyether impression materials, to the base paste or to a base paste component. The patient with the atypical clinical symptoms did not show any positive patch test reactions. Polyether impression materials may evoke type IV allergic reactions. The causative agent was a component of the base paste. In consideration of the widespread use of this impression material (millions of applications per year) and in comparison to the number of adverse reactions from other dental materials, the number of such allergic reactions is very low. In very scarce cases, positive allergic reactions to polyether impression materials are possible.

Use of an identification system based on biometric data for patients requiring transfusions guarantees transfusion safety and traceability

PubMed Central

Bennardello, Francesco; Fidone, Carmelo; Cabibbo, Sergio; Calabrese, Salvatore; Garozzo, Giovanni; Cassarino, Grazia; Antolino, Agostino; Tavolino, Giuseppe; Zisa, Nuccio; Falla, Cadigia; Drago, Giuseppe; Di Stefano, Giovanna; Bonomo, Pietro

2009-01-01

Background One of the most serious risks of blood transfusions is an error in ABO blood group compatibility, which can cause a haemolytic transfusion reaction and, in the most severe cases, the death of the patient. The frequency and type of errors observed suggest that these are inevitable, in that mistakes are inherent to human nature, unless significant changes, including the use of computerised instruments, are made to procedures. Methods In order to identify patients who are candidates for the transfusion of blood components and to guarantee the traceability of the transfusion, the Securblood system (BBS srl) was introduced. This system records the various stages of the transfusion process, the health care workers involved and any immediate transfusion reactions. The patients and staff are identified by fingerprinting or a bar code. The system was implemented within Ragusa hospital in 16 operative units (ordinary wards, day hospital, operating theatres). Results In the period from August 2007 to July 2008, 7282 blood components were transfused within the hospital, of which 5606 (77%) using the Securblood system. Overall, 1777 patients were transfused. In this year of experience, no transfusion errors were recorded and each blood component was transfused to the right patient. We recorded 33 blocks of the terminals (involving 0.6% of the transfused blood components) which required the intervention of staff from the Service of Immunohaematology and Transfusion Medicine (SIMT). Most of the blocks were due to procedural errors. Conclusions The Securblood system guarantees complete traceability of the transfusion process outside the SIMT and eliminates the possibility of mistaken identification of patients or blood components. The use of fingerprinting to identify health care staff (nurses and doctors) and patients obliges the staff to carry out the identification procedures directly in the presence of the patient and guarantees the presence of the doctor at the start of the transfusion. PMID:19657483

Use of an identification system based on biometric data for patients requiring transfusions guarantees transfusion safety and traceability.

PubMed

Bennardello, Francesco; Fidone, Carmelo; Cabibbo, Sergio; Calabrese, Salvatore; Garozzo, Giovanni; Cassarino, Grazia; Antolino, Agostino; Tavolino, Giuseppe; Zisa, Nuccio; Falla, Cadigia; Drago, Giuseppe; Di Stefano, Giovanna; Bonomo, Pietro

2009-07-01

One of the most serious risks of blood transfusions is an error in ABO blood group compatibility, which can cause a haemolytic transfusion reaction and, in the most severe cases, the death of the patient. The frequency and type of errors observed suggest that these are inevitable, in that mistakes are inherent to human nature, unless significant changes, including the use of computerised instruments, are made to procedures. In order to identify patients who are candidates for the transfusion of blood components and to guarantee the traceability of the transfusion, the Securblood system (BBS srl) was introduced. This system records the various stages of the transfusion process, the health care workers involved and any immediate transfusion reactions. The patients and staff are identified by fingerprinting or a bar code. The system was implemented within Ragusa hospital in 16 operative units (ordinary wards, day hospital, operating theatres). In the period from August 2007 to July 2008, 7282 blood components were transfused within the hospital, of which 5606 (77%) using the Securblood system. Overall, 1777 patients were transfused. In this year of experience, no transfusion errors were recorded and each blood component was transfused to the right patient. We recorded 33 blocks of the terminals (involving 0.6% of the transfused blood components) which required the intervention of staff from the Service of Immunohaematology and Transfusion Medicine (SIMT). Most of the blocks were due to procedural errors. The Securblood system guarantees complete traceability of the transfusion process outside the SIMT and eliminates the possibility of mistaken identification of patients or blood components. The use of fingerprinting to identify health care staff (nurses and doctors) and patients obliges the staff to carry out the identification procedures directly in the presence of the patient and guarantees the presence of the doctor at the start of the transfusion.

Optical properties of in-vitro biomineralised silica.

PubMed

Polini, Alessandro; Pagliara, Stefano; Camposeo, Andrea; Cingolani, Roberto; Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G; Pisignano, Dario

2012-01-01

Silicon is the second most common element on the Earth's crust and its oxide (SiO(2)) the most abundant mineral. Silica and silicates are widely used in medicine and industry as well as in micro- and nano-optics and electronics. However, the fabrication of glass fibres and components requires high temperature and non-physiological conditions, in contrast to biosilica structures in animals and plants. Here, we show for the first time the use of recombinant silicatein-α, the most abundant subunit of sponge proteins catalyzing biosilicification reactions, to direct the formation of optical waveguides in-vitro through soft microlithography. The artificial biosilica fibres mimic the natural sponge spicules, exhibiting refractive index values suitable for confinement of light within waveguides, with optical losses in the range of 5-10 cm(-1), suitable for application in lab-on-chips systems. This method extends biosilicification to the controlled fabrication of optical components by physiological processing conditions, hardly addressed by conventional technologies.

[Impacts of airborne particulate matter and its components on respiratory system health].

PubMed

Cao, L M; Zhou, Y; Zhang, Z; Sun, W W; Mu, G; Chen, W H

2016-12-06

Nowadays, particulate air pollution has been a global environmental problem. Numerous studies has shown that long-term exposure to high level of airborne particulate matter (PM) can damage human health. Respiratory system, as a direct portal to contact with particulate matter, can be more susceptible to airborne particulates. Summarizing latest five-year epidemiological research, the present review is focused on the effects of PM on respiratory system health in different age groups. In detail, we investigated the harmful effect of PM, or its components on three common respiratory diseases, including lung function decline, chronic obstructive pulmonary disease (COPD) and asthma. The result showed that, to a certain degree, PM could induce the decline of lung function, the development and the exacerbation of COPD and asthma by oxidative stress and inflammatory reaction. And it may prompt that exposure to PM can be an improtant risk factor for the respiratory system health.

Process for producing dispersed particulate composite materials

DOEpatents

Henager, Jr., Charles H.; Hirth, John P.

1995-01-01

This invention is directed to a process for forming noninterwoven dispersed particulate composite products. In one case a composite multi-layer film product comprises a substantially noninterwoven multi-layer film having a plurality of discrete layers. This noninterwoven film comprises at least one discrete layer of a first material and at least one discrete layer of a second material. In another case the first and second materials are blended together with each other. In either case, the first material comprises a metalloid and the second material a metal compound. At least one component of a first material in one discrete layer undergoes a solid state displacement reaction with at least one component of a second material thereby producing the requisite noninterwoven composite film product. Preferably, the first material comprises silicon, the second material comprises Mo.sub.2 C, the third material comprises SiC and the fourth material comprises MoSi.sub.2.

The components of Melissa officinalis L. that influence protein biosynthesis in-vitro.

PubMed

Chlabicz, J; Gałasiński, W

1986-11-01

An investigation of an inhibiting activity of a substance(s) in a tanninless extract from Melissa officinalis leaves on protein biosynthesis in-vitro has been made. At least two components which inhibited protein biosynthesis were present in the extract; these were caffeic acid and an unidentified glycoside. Freshly prepared buffered solutions of caffeic acid inhibited protein biosynthesis less than solutions stored for several days at room temperature (20 degrees C). In this case derivatives of caffeic acid were formed, which may be responsible for the increase in the inhibitory effect of stored caffeic acid solution. An inhibitor, in the homogeneous state, was also isolated from the glycoside fraction of M. officinalis. Studies on the mechanism of the action of this inhibitor revealed its effect is to use the result of a direct interaction with elongation factor EF-2, and the blocking of the binding reaction of EF-2 with ribosomes.

Social cognition in Intermittent Explosive Disorder and aggression

PubMed Central

Coccaro, Emil F.; Fanning, Jennifer R.; Keedy, Sarah K.; Lee, Royce J.

2017-01-01

Social-emotional information processing (SEIP) was assessed in individuals with current DSM-5 Intermittent Explosive Disorder (IED: n = 100) and in healthy (n = 100) and psychiatric (n = 100) controls using a recently developed and validated self-rated questionnaire. SEIP vignettes depicted both direct aggressive and relationally aggressive scenarios of a socially ambiguous nature and were followed by questions assessing subjects' reactions and judgments about the vignettes. IED subjects differed from both healthy and psychiatric controls in all SEIP components. While hostile attribution was highly related to history of aggression, it was also directly correlated with negative emotional response. Further analysis revealed that this component, as well as response valuation and response efficiency, rather than hostile attribution, best explained history of aggressive behavior. A reformulated SEIP model, including self-reported history of childhood trauma, found that negative emotional response and response efficiency were the critical correlates for history of aggressive behavior. Psychosocial interventions of aggressive behavior in IED subjects may do well to include elements that work to reduce the emotional response to social threat and that work to restructure social cognition so that the tendency towards overt, or relationally, aggressive responding is reduced. PMID:27621104

Social cognition in Intermittent Explosive Disorder and aggression.

PubMed

Coccaro, Emil F; Fanning, Jennifer R; Keedy, Sarah K; Lee, Royce J

2016-12-01

Social-emotional information processing (SEIP) was assessed in individuals with current DSM-5 Intermittent Explosive Disorder (IED: n = 100) and in healthy (n = 100) and psychiatric (n = 100) controls using a recently developed and validated self-rated questionnaire. SEIP vignettes depicted both direct aggressive and relationally aggressive scenarios of a socially ambiguous nature and were followed by questions assessing subjects' reactions and judgments about the vignettes. IED subjects differed from both healthy and psychiatric controls in all SEIP components. While hostile attribution was highly related to history of aggression, it was also directly correlated with negative emotional response. Further analysis revealed that this component, as well as response valuation and response efficiency, rather than hostile attribution, best explained history of aggressive behavior. A reformulated SEIP model, including self-reported history of childhood trauma, found that negative emotional response and response efficiency were the critical correlates for history of aggressive behavior. Psychosocial interventions of aggressive behavior in IED subjects may do well to include elements that work to reduce the emotional response to social threat and that work to restructure social cognition so that the tendency towards overt, or relationally, aggressive responding is reduced. Copyright © 2016. Published by Elsevier Ltd.

Synthesis of zwitterionic salts of pyridinium-Meldrum acid and barbiturate through unique four-component reactions.

PubMed

Wang, Qi-Fang; Hui, Li; Hou, Hong; Yan, Chao-Guo

2010-03-08

An efficient synthetic procedure for the preparation of the unusual charge-separated pyridinium-Meldrum acid and N,N-dimethylbarbiturate acid zwitterionic salts was developed though a unique one-pot four-component reaction involving pyridine, aromatic aldehyde, Meldrum acid or N,N-dimethylbarbituric acid, and p-nitrobenzyl bromide in acetonitrile. By varying combinations of four components involving nitrogen-containing heterocycles, we conveniently established reactive alpha-halomethylene compounds, aldehydes and beta-dicarbonyl compounds a library of zwitterionic salts.

Self-assembly concepts in the formation of nanostructured particles using a liquid-phase synthesis method

NASA Astrophysics Data System (ADS)

Nandiyanto, Asep Bayu Dani

2016-02-01

When synthesizing particles using a liquid-phase synthesis method, reactant components show interaction with the reaction system itself. However, current reports described successful synthesis of material with only partial information on the component-component interaction and possible self-assembly mechanism occurring during the material synthesis process. Here, self-assembly concepts in the formation of nanostructured particles are presented. Influences of self-assembly parameters (i.e., surface charge, size, and concentration of components involving the reaction) on self-organized material fabrication are described. Because understanding the interaction of the component provides significant information in regard to practical uses, this report can be relevant to further material development and fabrication.

From lignin to cycloparaffins and aromatics: directional synthesis of jet and diesel fuel range biofuels using biomass.

PubMed

Bi, Peiyan; Wang, Jicong; Zhang, Yajing; Jiang, Peiwen; Wu, Xiaoping; Liu, Junxu; Xue, He; Wang, Tiejun; Li, Quanxin

2015-05-01

The continual growth in commercial aviation fuels and more strict environmental legislations have led to immense interest in developing green aviation fuels from biomass. This paper demonstrated a controllable transformation of lignin into jet and diesel fuel range hydrocarbons, involving directional production of C8-C15 aromatics by the catalytic depolymerization of lignin into C6-C8 low carbon aromatic monomers coupled with the alkylation of aromatics, and the directional production of C8-C15 cycloparaffins by the hydrogenation of aromatics. The key step, the production of the desired C8-C15 aromatics with the selectivity up to 94.3%, was achieved by the low temperature alkylation reactions of the lignin-derived monomers using ionic liquid. The synthetic biofuels basically met the main technical requirements of conventional jet fuels. The transformation potentially provides a useful way for the development of cycloparaffinic and aromatic components in jet fuels using renewable lignocellulose biomass. Copyright © 2015. Published by Elsevier Ltd.

Experimental demonstration of a single-molecule electric motor.

PubMed

Tierney, Heather L; Murphy, Colin J; Jewell, April D; Baber, Ashleigh E; Iski, Erin V; Khodaverdian, Harout Y; McGuire, Allister F; Klebanov, Nikolai; Sykes, E Charles H

2011-09-04

For molecules to be used as components in molecular machines, methods that couple individual molecules to external energy sources and that selectively excite motion in a given direction are required. Significant progress has been made in the construction of molecular motors powered by light and by chemical reactions, but electrically driven motors have not yet been built, despite several theoretical proposals for such motors. Here we report that a butyl methyl sulphide molecule adsorbed on a copper surface can be operated as a single-molecule electric motor. Electrons from a scanning tunnelling microscope are used to drive the directional motion of the molecule in a two-terminal setup. Moreover, the temperature and electron flux can be adjusted to allow each rotational event to be monitored at the molecular scale in real time. The direction and rate of the rotation are related to the chiralities of both the molecule and the tip of the microscope (which serves as the electrode), illustrating the importance of the symmetry of the metal contacts in atomic-scale electrical devices.

Thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell in combined heat and power applications

NASA Astrophysics Data System (ADS)

Abraham, F.; Dincer, I.

2015-12-01

This paper presents a comprehensive steady state modelling and thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell integrated with Gas Turbine power cycle (DU-SOFC/GT). The use of urea as direct fuel mitigates public health and safety risks associated with the use of hydrogen and ammonia. The integration scheme in this study covers both oxygen ion-conducting solid oxide fuel cells (SOFC-O) and hydrogen proton-conducting solid oxide fuel cells (SOFC-H). Parametric case studies are carried out to investigate the effects of design and operating parameters on the overall performance of the system. The results reveal that the fuel cell exhibited the highest level of exergy destruction among other system components. Furthermore, the SOFC-O based system offers better overall performance than that with the SOFC-H option mainly due to the detrimental reverse water-gas shift reaction at the SOFC anode as well as the unique configuration of the system.

Palladium-catalyzed three-component reaction of N-tosyl hydrazones, isonitriles and amines leading to amidines.

PubMed

Dai, Qiang; Jiang, Yan; Yu, Jin-Tao; Cheng, Jiang

2015-12-04

A palladium-catalyzed three-component reaction between N-tosyl hydrazones, aryl isonitriles and amines was developed, leading to amidines in moderate to good yields. This procedure features the rapid construction of amidine frameworks with high diversity and complexity. Ketenimines serve as intermediates, which encounter nucleophilic attack by amines to produce amidines.

A Green Multicomponent Reaction for the Organic Chemistry Laboratory: The Aqueous Passerini Reaction

ERIC Educational Resources Information Center

Hooper, Matthew M.; DeBoef, Brenton

2009-01-01

Water is the ideal green solvent for organic reactions. However, most organic molecules are insoluble in it. Herein, we report a laboratory module that takes advantage of this property. The Passerini reaction, a three-component coupling involving an isocyanide, aldehyde, and carboxylic acid, typically requires [similar to] 24 h reaction times in…

Facile characterization of ripple domains on exfoliated graphene.

PubMed

Choi, Jin Sik; Kim, Jin-Soo; Byun, Ik-Su; Lee, Duk Hyun; Hwang, In Rok; Park, Bae Ho; Choi, Taekjib; Park, Jeong Young; Salmeron, Miquel

2012-07-01

Ripples in graphene monolayers deposited on SiO(2)/Si wafer substrates were recently shown to give rise to friction anisotropy. High friction appears when the AFM tip slides in a direction perpendicular to the ripple crests and low friction when parallel. The direction of the ripple crest is, however, hard to determine as it is not visible in topographic images and requires elaborate measurements of friction as a function of angle. Here we report a simple method to characterize ripple crests by measuring the cantilever torsion signal while scanning in the non-conventional longitudinal direction (i.e., along the cantilever axis, as opposed to the usual friction measurement). The longitudinal torsion signal provides a much clearer ripple domain contrast than the conventional friction signal, while both signals show respective rotation angle dependences that can be explained using the torsion component of the normal reaction force exerted by the graphene ripples. We can also determine the ripple direction by comparing the contrast in torsion images obtained in longitudinal and lateral scans without sample rotation or complicated normalization.

Controllable molecular motors engineered from myosin and RNA

NASA Astrophysics Data System (ADS)

Omabegho, Tosan; Gurel, Pinar S.; Cheng, Clarence Y.; Kim, Laura Y.; Ruijgrok, Paul V.; Das, Rhiju; Alushin, Gregory M.; Bryant, Zev

2018-01-01

Engineering biomolecular motors can provide direct tests of structure-function relationships and customized components for controlling molecular transport in artificial systems1 or in living cells2. Previously, synthetic nucleic acid motors3-5 and modified natural protein motors6-10 have been developed in separate complementary strategies to achieve tunable and controllable motor function. Integrating protein and nucleic-acid components to form engineered nucleoprotein motors may enable additional sophisticated functionalities. However, this potential has only begun to be explored in pioneering work harnessing DNA scaffolds to dictate the spacing, number and composition of tethered protein motors11-15. Here, we describe myosin motors that incorporate RNA lever arms, forming hybrid assemblies in which conformational changes in the protein motor domain are amplified and redirected by nucleic acid structures. The RNA lever arm geometry determines the speed and direction of motor transport and can be dynamically controlled using programmed transitions in the lever arm structure7,9. We have characterized the hybrid motors using in vitro motility assays, single-molecule tracking, cryo-electron microscopy and structural probing16. Our designs include nucleoprotein motors that reversibly change direction in response to oligonucleotides that drive strand-displacement17 reactions. In multimeric assemblies, the controllable motors walk processively along actin filaments at speeds of 10-20 nm s-1. Finally, to illustrate the potential for multiplexed addressable control, we demonstrate sequence-specific responses of RNA variants to oligonucleotide signals.

Reaction time for processing visual stimulus in a computer-assisted rehabilitation environment.

PubMed

Sanchez, Yerly; Pinzon, David; Zheng, Bin

2017-10-01

To examine the reaction time when human subjects process information presented in the visual channel under both a direct vision and a virtual rehabilitation environment when walking was performed. Visual stimulus included eight math problems displayed on the peripheral vision to seven healthy human subjects in a virtual rehabilitation training (computer-assisted rehabilitation environment (CAREN)) and a direct vision environment. Subjects were required to verbally report the results of these math calculations in a short period of time. Reaction time measured by Tobii Eye tracker and calculation accuracy were recorded and compared between the direct vision and virtual rehabilitation environment. Performance outcomes measured for both groups included reaction time, reading time, answering time and the verbal answer score. A significant difference between the groups was only found for the reaction time (p = .004). Participants had more difficulty recognizing the first equation of the virtual environment. Participants reaction time was faster in the direct vision environment. This reaction time delay should be kept in mind when designing skill training scenarios in virtual environments. This was a pilot project to a series of studies assessing cognition ability of stroke patients who are undertaking a rehabilitation program with a virtual training environment. Implications for rehabilitation Eye tracking is a reliable tool that can be employed in rehabilitation virtual environments. Reaction time changes between direct vision and virtual environment.

Characterizing Pyroxene Reaction Space in Calcium-Aluminum Rich Inclusions: Oxidation During CAI Rim Formation

NASA Astrophysics Data System (ADS)

Dyl, K. A.; Young, E. D.

2009-12-01

We define the reaction space that controls changes in pyroxene composition in CAIs and Wark-Lovering (WL) rims in an oxidizing solar nebula. Ti-rich pyroxenes in CAIs record a sub-solar oxygen fugacity (Ti3+/Ti4+~1.5). WL rim pyroxenes in the CAI Leoville 144A have a distinctly lower oxidation state.This difference supports WL rim condensation in an environment of increasing O2(g) and Mg(g) (Simon et al. 2005). We used the following phase components to identify four linearly independent reactions (Thompson 1982): diopside, CaTs (Al2Mg-1Si-1), T3 (Ti3+AlMg-1Si-1), T4 (Ti4+Al2Mg-1Si-2), En (MgCa-1), perovskite, O(g), Mg(g), SiO(g), and Ca(g). Compositional variation in this system is dominated by two reactions. The first is oxidation of Ti3+ via reaction with O and Mg in the gas phase: 1.5 O(g) + Mg(g) → ¼ Di + [Ti4+Mg3/4Ti3+-1Ca-1/4Si-1/2] (1). Pyroxene is produced and En is introduced. The second reaction (2) is perovskite formation. It is observed in the WL rim of Leoville 144A, and experiments confirm that an elevated Ti component converts pyroxene to perovskite(Gupta et al. 1973). MgCa-1 is the third linearly independent reaction (3). They combine to give: ½ Di + x Ca(g)→ x Mg(g)+ Pv + [Mg1/2-xSiTi4+-1Ca-1/2+x](2,3). Unlike (1), pyroxene is consumed in this reaction. The parameter x defines the extent of Mg-Ca exchange. When x > 0.5, WL rim formation occurs in an environment where Mg is volatile and Ca condenses. The reaction space defined by reactions (1) and (2,3) describes the transition from CAI interior to WL rims. WL rim pyroxene Ti contents, [CaTs], and Ca < 1 pfu are all explained in this space. The fourth linearly independent reaction is SiO(g):1/8 Di + ¼ Mg(g)→ ¾ SiO(g) + [Mg3/8Ca1/8Ti4+Ti3+-1Si-1/2](4). Silica reduction forms Ti4+, releasing SiO(g). (4) does not describe the oxidation of Ti3+ in WL rim pyroxene, but (1) - (4) results in En formation directly from the gas phase. This may explain WL rim analyses that have Si contents in excess of those predicted from reactions (1) and (2,3). Simon et al. (2005) EPSL 41, 272-283; Thompson (1982)Rev. Min. 10, 33-52; Gupta et al. (1973) Contr. Mineral. Petrol. 41, 333-344 Reaction space for CAI pyroxene. Pyroxenes plotted using titanium contents.

On understanding nuclear reaction network flows with branchings on directed graphs

NASA Astrophysics Data System (ADS)

Meyer, Bradley S.

2018-04-01

Nuclear reaction network flow diagrams are useful for understanding which reactions are governing the abundance changes at a particular time during nucleosynthesis. This is especially true when the flows are largely unidirectional, such as during the s-process of nucleosynthesis. In explosive nucleosynthesis, when reaction flows are large, and when forward reactions are nearly balanced by their reverses, reaction flows no longer give a clear picture of the abundance evolution in the network. This paper presents a way of understanding network evolution in terms of sums of branchings on a directed graph, which extends the concept of reaction flows to allow for multiple reaction pathways.

Interface Reactions and Synthetic Reaction of Composite Systems

PubMed Central

Park, Joon Sik; Kim, Jeong Min

2010-01-01

Interface reactions in composite systems often determine their overall properties, since product phases usually formed at interfaces during composite fabrication processing make up a large portion of the composites. Since most composite materials represent a ternary or higher order materials system, many studies have focused on analyses of diffusion phenomena and kinetics in multicomponent systems. However, the understanding of the kinetic behavior increases the complexity, since the kinetics of each component during interdiffusion reactions need to be defined for interpreting composite behaviors. From this standpoint, it is important to clarify the interface reactions for producing compatible interfaces with desired product phases. A thermodynamic evaluation such as a chemical potential of involving components can provide an understanding of the diffusion reactions, which govern diffusion pathways and product phase formation. A strategic approach for designing compatible interfaces is discussed in terms of chemical potential diagrams and interface morphology, with some material examples.

Catalytic reactor

DOEpatents

Aaron, Timothy Mark [East Amherst, NY; Shah, Minish Mahendra [East Amherst, NY; Jibb, Richard John [Amherst, NY

2009-03-10

A catalytic reactor is provided with one or more reaction zones each formed of set(s) of reaction tubes containing a catalyst to promote chemical reaction within a feed stream. The reaction tubes are of helical configuration and are arranged in a substantially coaxial relationship to form a coil-like structure. Heat exchangers and steam generators can be formed by similar tube arrangements. In such manner, the reaction zone(s) and hence, the reactor is compact and the pressure drop through components is minimized. The resultant compact form has improved heat transfer characteristics and is far easier to thermally insulate than prior art compact reactor designs. Various chemical reactions are contemplated within such coil-like structures such that as steam methane reforming followed by water-gas shift. The coil-like structures can be housed within annular chambers of a cylindrical housing that also provide flow paths for various heat exchange fluids to heat and cool components.

Controlled Microwave Heating Accelerates Rolling Circle Amplification.

PubMed

Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

2015-01-01

Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same.

An ylide transformation of rhodium(I) carbene: enantioselective three-component reaction through trapping of rhodium(I)-associated ammonium ylides by β-nitroacrylates.

PubMed

Ma, Xiaochu; Jiang, Jun; Lv, Siying; Yao, Wenfeng; Yang, Yang; Liu, Shunying; Xia, Fei; Hu, Wenhao

2014-11-24

The chiral Rh(I)-diene-catalyzed asymmetric three-component reaction of aryldiazoacetates, aromatic amines, and β-nitroacrylates was achieved to obtain γ-nitro-α-amino-succinates in good yields and with high diastereo- and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of Rh(I)-associated ammonium ylides by nitroacrylates. This new transformation represents the first example of Rh(I)-carbene-induced ylide transformation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MAX phase – Alumina composites via elemental and exchange reactions in the Ti{sub n+1}AC{sub n} systems (A=Al, Si, Ga, Ge, In and Sn)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuskelly, Dylan, E-mail: dylan.cuskelly@uon.edu.au; Richards, Erin; Kisi, Erich, E-mail: Erich.Kisi@newcastle.edu.au

2016-05-15

Extension of the aluminothermal exchange reaction synthesis of M{sub n+1}AX{sub n} phases to systems where the element ‘A’ is not the reducing agent was investigated in systems TiO{sub 2}–A–Al–C for A=Al, Si, Ga, Ge, In and Sn as well as Cr{sub 2}O{sub 3}–Ga–Al–C. MAX phase-Al{sub 2}O{sub 3} composites were made in all systems except those with A=Ga or In. The effectiveness of conversion to MAX phases was generally in the range 63–96% without optimisation of starting ratios. Optimisation in the Ti–Si–C system gave a MAX phase component with >98% Ti{sub 3}SiC{sub 2}. - Graphical abstract: A range of Ti{sub n+1}AX{submore » n} phases with different A elements were synthesised directly from the M oxide via exchange reactions. The process has now been shown to be general in all the systems marked in green in the table. - Highlights: • Ti{sub n+1}AC{sub n} phases were produced via a single step exchange reaction. • 3 MAX phase systems were successful via this method for the first time. • Cr{sub 2}GeC was also able to be produced via an exchange reaction. • The interconversion reaction in MAX phases is more general than previously thought.« less

The effects of combined caffeine and glucose drinks on attention in the human brain.

PubMed

Rao, Anling; Hu, Henglong; Nobre, Anna Christina

2005-06-01

The objective of this research was to measure the effects of energising drinks containing caffeine and glucose, upon mental activity during sustained selective attention. Non-invasive electrophysiological brain recordings were made during a behavioural study of selective attention in which participants received either energising or placebo drinks. We tested specifically whether energising drinks have significant effects upon behavioural measures of performance during a task requiring sustained visual selective attention, as well as on accompanying components of the event-related potential (ERPs) related to information processing in the brain. Forty healthy volunteers were blindly assigned to receive either the energising drink or a similar-tasting placebo drink. The behavioural task involved identifying predefined target stimulus among rapidly presented streams of peripheral visual stimuli, and making speeded motor responses to this stimulus. During task performance, accuracy, reaction times and ongoing brain activity were stored for analysis. The energising drink enhanced behavioural performance both in terms of accuracy and speed of reactions. The energising drink also had significant effects upon the event-related potentials. Effects started from the enhancement of the earliest components (Cl/P1), reflecting early visual cortical processing in the energising-drink group relative to the placebo group over the contralateral scalp. The later N1, N2 and P3 components related to decision-making and responses were also modulated by the energising drink. Energising drinks containing caffeine and glucose can enhance behavioural performance during demanding tasks requiring selective attention. The behavioural benefits are coupled to direct effects upon neural information processing.

A haemovigilance team provides both significant financial and quality benefits in a University Hospital.

PubMed

Decadt, Ine; Costermans, Els; Van de Poel, Maai; Kesteloot, Katrien; Devos, Timothy

2017-04-01

Haemovigilance is the process of surveillance of blood transfusion procedures including unexpected hazards and reactions during the transfusion pathway in both donors and recipients. The haemovigilance team aims to increase blood transfusion safety and to decrease both morbidity and mortality in donors and recipients. The team collects data about transfusion reactions and incidents, instructs the involved health workers and assures the tracing of blood components. The haemovigilance team at the University Hospitals Leuven has played a pioneering role in the development of haemovigilance in Belgium Although the literature about safety and quality improvements by haemovigilance systems is abundant, there are no published data available measuring their financial impact in a hospital. Therefore, we studied the costs and returns of the haemovigilance team at the University Hospitals Leuven. This study has a descriptive explorative design. Research of the current costs and returns of the haemovigilance team were based upon data from the Medical Administration of the hospital. Data were analyzed descriptively. The haemovigilance team of the University Hospitals Leuven is financially viable: the direct costs are covered by the annual financial support of the National Public Health Service. The indirect returns come from two important tasks of the haemovigilance team itself: correction of the electronic registration of administered blood component and improvement of the return of conform preserved blood components to the blood bank. Besides safety and quality improvement, which are obviously their main goals, the haemovigilance team also implies a financial benefit for the hospital. Copyright © 2016 Elsevier Ltd. All rights reserved.

“How Did You Feel?”: Increasing Child Sexual Abuse Witnesses’ Production of Evaluative Information

PubMed Central

Lyon, Thomas D.; Scurich, Nicholas; Choi, Karen; Handmaker, Sally; Blank, Rebecca

2014-01-01

In child sexual abuse cases, the victim’s testimony is essential, because the victim and the perpetrator tend to be the only eyewitnesses to the crime. A potentially important component of an abuse report is the child’s subjective reactions to the abuse. Attorneys may ask suggestive questions or avoid questioning children about their reactions, assuming that children, given their immaturity and reluctance, are incapable of articulation. We hypothesized that How questions referencing reactions to abuse (e.g., “how did you feel”) would increase the productivity of children’s descriptions of abuse reactions. Two studies compared the extent to which children provided evaluative content, defined as descriptions of emotional, cognitive, and physical reactions, in response to different question-types, including How questions, Wh-questions, Option-posing questions (yes–no or forced-choice), and Suggestive questions. The first study examined children’s testimony (ages 5–18) in 80 felony child sexual abuse cases. How questions were more productive yet the least prevalent, and Option-posing and Suggestive questions were less productive but the most common. The second study examined interview transcripts of 61 children (ages 6 –12) suspected of being abused, in which children were systematically asked How questions regarding their reactions to abuse, thus controlling for the possibility that in the first study, attorneys selectively asked How questions of more articulate children. Again, How questions were most productive in eliciting evaluative content. The results suggest that interviewers and attorneys interested in eliciting evaluative reactions should ask children “how did you feel?” rather than more direct or suggestive questions. PMID:22309936

Phenotypic plasticity of nest timing in a post-glacial landscape: how do reptiles adapt to seasonal time constraints?

PubMed

Edge, Christopher B; Rollinson, Njal; Brooks, Ronald J; Congdon, Justin D; Iverson, John B; Janzen, Fredric J; Litzgus, Jacqueline D

2017-02-01

Life histories evolve in response to constraints on the time available for growth and development. Nesting date and its plasticity in response to spring temperature may therefore be important components of fitness in oviparous ectotherms near their northern range limit, as reproducing early provides more time for embryos to complete development before winter. We used data collected over several decades to compare air temperature and nest date plasticity in populations of painted turtles and snapping turtles from a relatively warm environment (southeastern Michigan) near the southern extent of the last glacial maximum to a relatively cool environment (central Ontario) near the northern extent of post-glacial recolonization. For painted turtles, population-level differences in reaction norm elevation for two phenological traits were consistent with adaptation to time constraints, but no differences in reaction norm slopes were observed. For snapping turtle populations, the difference in reaction norm elevation for a single phenological trait was in the opposite direction of what was expected under adaptation to time constraints, and no difference in reaction norm slope was observed. Finally, among-individual variation in individual plasticity for nesting date was detected only in the northern population of snapping turtles, suggesting that reaction norms are less canalized in this northern population. Overall, we observed evidence of phenological adaptation, and possibly maladaptation, to time constraints in long-lived reptiles. Where present, (mal)adaptation occurred by virtue of differences in reaction norm elevation, not reaction norm slope. Glacial history, generation time, and genetic constraint may all play an important role in the evolution of phenological timing and its plasticity in long-lived reptiles. © 2016 by the Ecological Society of America.

5-Oxyoprolinase: Structure and mechanism of action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, L.

1988-01-01

5-Oxoprolinase catalyzes the endergonic cleavage of 5-oxo-L-proline to L-glutamate, coupled to the exergonic hydrolysis of ATP to ADP and P{sub i}. In the present studies, the enzyme present in a strain of Pseudomonas putida was found to be composed of two protein components. Component A catalyzes 5-oxo-L-proline-dependent cleavage of ATP without 5-oxyoproline decyclization. Component B is required to couple ATP hydrolysis to the ring-opening of 5-oxoproline. The two components have been purified to apparent homogeneity. When the 5-oxoprolinase reactions were carried out to 90% completion in H{sub 2} {sup 18}O, the residual 5-oxoproline contained {sup 18}O in the amide carbonylmore » group. Glutamate and P{sub i} isolated from the complete reactions conducted in H{sub 2}{sup 18}O were mono- and di-labeled with the isotope. No isotope was incorporated into 5-oxoproline if Component A was used alone. Studies with 5-oxoproline analogs showed that dilabeling of P{sub i} occurred only in coupled or partially coupled reactions. Using 5-({sup 18}O)oxo-L-(5-{sup 13}C)proline, the reactions were further analyzed by {sup 13}C-NMR. 5-Oxoprolinase from rat kidney was used as a comparison in all mechanistic studies, and similar results were obtained. These findings are consistent with the view that the reaction involves enzyme-bound, phosphorylated intermediates, and provided strong evidence for a phosphorylated tetrahedral intermediate, the formation of which is required for the coupling.« less

Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions† †Electronic supplementary information (ESI) available: Detailed experimental and computational results, procedures, characterization data, copies of NMR charts, and crystallographic data. CCDC 1572238. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04675h

PubMed Central

Fukuoka, Asuka; Yokoyama, Wataru; Min, Xin; Hisaki, Ichiro; Kuniyasu, Hitoshi

2018-01-01

We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C–C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded via nucleophilic attack of the Ni center toward the alkyl fluorides. These steps are found to be the rate-determining and selectivity-determining steps of the whole catalytic cycle, in which the C–F bond of the alkyl fluorides is activated by the Mg cation rather than a Li or Zn cation. ortho-Substituents of the aryl Grignard reagents suppressed the cross-coupling reaction leading to the selective formation of the four-component products. Such steric effects of the ortho-substituents were clearly demonstrated by crystal structure characterizations of ate complexes and DFT calculations. The electronic effects of the para-substituent of the aryl Grignard reagents on both the selectivity and reaction rates are thoroughly discussed. The present mechanistic study offers new insight into anionic complexes, which are proposed as the key intermediates in catalytic transformations even though detailed mechanisms are not established in many cases, and demonstrates their synthetic utility as promising intermediates for C–C bond forming reactions, providing useful information for developing efficient and straightforward multicomponent reactions. PMID:29719693

Multi-enzyme complexes on DNA scaffolds capable of substrate channelling with an artificial swinging arm

NASA Astrophysics Data System (ADS)

Fu, Jinglin; Yang, Yuhe Renee; Johnson-Buck, Alexander; Liu, Minghui; Liu, Yan; Walter, Nils G.; Woodbury, Neal W.; Yan, Hao

2014-07-01

Swinging arms are a key functional component of multistep catalytic transformations in many naturally occurring multi-enzyme complexes. This arm is typically a prosthetic chemical group that is covalently attached to the enzyme complex via a flexible linker, allowing the direct transfer of substrate molecules between multiple active sites within the complex. Mimicking this method of substrate channelling outside the cellular environment requires precise control over the spatial parameters of the individual components within the assembled complex. DNA nanostructures can be used to organize functional molecules with nanoscale precision and can also provide nanomechanical control. Until now, protein-DNA assemblies have been used to organize cascades of enzymatic reactions by controlling the relative distance and orientation of enzymatic components or by facilitating the interface between enzymes/cofactors and electrode surfaces. Here, we show that a DNA nanostructure can be used to create a multi-enzyme complex in which an artificial swinging arm facilitates hydride transfer between two coupled dehydrogenases. By exploiting the programmability of DNA nanostructures, key parameters including position, stoichiometry and inter-enzyme distance can be manipulated for optimal activity.

Multi-enzyme complexes on DNA scaffolds capable of substrate channelling with an artificial swinging arm.

PubMed

Fu, Jinglin; Yang, Yuhe Renee; Johnson-Buck, Alexander; Liu, Minghui; Liu, Yan; Walter, Nils G; Woodbury, Neal W; Yan, Hao

2014-07-01

Swinging arms are a key functional component of multistep catalytic transformations in many naturally occurring multi-enzyme complexes. This arm is typically a prosthetic chemical group that is covalently attached to the enzyme complex via a flexible linker, allowing the direct transfer of substrate molecules between multiple active sites within the complex. Mimicking this method of substrate channelling outside the cellular environment requires precise control over the spatial parameters of the individual components within the assembled complex. DNA nanostructures can be used to organize functional molecules with nanoscale precision and can also provide nanomechanical control. Until now, protein-DNA assemblies have been used to organize cascades of enzymatic reactions by controlling the relative distance and orientation of enzymatic components or by facilitating the interface between enzymes/cofactors and electrode surfaces. Here, we show that a DNA nanostructure can be used to create a multi-enzyme complex in which an artificial swinging arm facilitates hydride transfer between two coupled dehydrogenases. By exploiting the programmability of DNA nanostructures, key parameters including position, stoichiometry and inter-enzyme distance can be manipulated for optimal activity.

[Chemical Potentials of Hydrothermal Systems and Formation of Coupled Modular Metabolic Pathways].

PubMed

Marakushev, S A; Belonogova, O V

2015-01-01

According to Gibbs J.W. the number of independent components is the least number of those chemical constituents, by combining which the compositions of all possible phases in the system can be obtained, and at the first stages of development of the primary metabolism of the three-component system C-H-O different hydrocarbons and molecular hydrogen were used as an energy source for, it. In the Archean hydrothermal conditions under the action of the phosphorus chemical potential the C-H-O system was transformed into a four-component system C-H-O-P setting up a gluconeogenic system, which became the basis of power supply for a protometabolism, and formation of a new cycle of CO2 fixation (reductive pentose phosphate pathway). It is shown that parageneses (association) of certain substances permitted the modular constructions of the central metabolism of the system C-H-O-P and the formed modules appear in association with each other in certain physicochemical hydrothermal conditions. Malate, oxaloacetate, pyruvate and phosphoenolpyruvate exhibit a turnstile-like mechanism of switching reaction directions.

Okara promoted acrylamide and carboxymethyl-lysine formation in bakery products.

PubMed

Palermo, Mariantonella; Fiore, Alberto; Fogliano, Vincenzo

2012-10-10

Soybeans are widely used in bakery products because of their technological advantages and, recently, soybean-containing products have been marketed as functional foods thanks to several health benefits. Okara is a soybean-based ingredient obtained after elimination of the water-soluble component from ground soybeans. In this paper the effect of okara addition to bakery products on the formation of some potentially harmful Maillard reaction products was evaluated. Cookies obtained by replacing 15% of wheat flour with okara showed a visible browning increase and a more intense Maillard reaction development as shown by higher concentrations of 5-hydroxymethyl-2-furaldehyde (HMF) (+100%), acrylamide (+60%), and carboxymethyl-lysine (CML) (+400%) with respect to the control. This phenomenon could be related to the presence in okara of about 50% of insoluble dietary fiber: the fiber reduces water activity during cooking, thus promoting Maillard reaction. To confirm this hypothesis, cookies obtained by replacing 7% of wheat flour with three different types of dietary fiber (cellulose, chitosan, and pea fiber) were prepared: these experimental cookies showed higher Maillard reaction product concentration with respect to the control and, in particular, HMF and CML values were directly related to the fiber water-holding capacity (WHC). To extend the observation to the food market, a sampling of soybean-containing commercial bakery products was analyzed by comparing the concentrations of Maillard reaction products with those of similar bakery products without soy. Soybean-containing samples showed higher concentrations of acrylamide and CML than corresponding controls.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casperson, R. J.; Burke, J. T.; Hughes, R. O.

Directly measuring (n,2n) cross sections on short-lived actinides presents a number of experimental challenges. The surrogate reaction technique is an experimental method for measuring cross sections on short-­lived isotopes, and it provides a unique solution for measuring (n,2n) cross sections. This technique involves measuring a charged-­particle reaction cross section, where the reaction populates the same compound nucleus as the reaction of interest. To perform these surrogate (n,2n) cross section measurements, a silicon telescope array has been placed along a beam line at the Texas A&M University Cyclotron Institute, which is surrounded by a large tank of gadolinium-doped liquid scintillator, whichmore » acts as a neutron detector. The combination of the charge-particle and neutron-detector arrays is referred to as NeutronSTARS. In the analysis procedure for calculating the (n,2n) cross section, the neutron detection efficiency and time structure plays an important role. Due to the lack of availability of isotropic, mono-energetic neutron sources, modeling is an important component in establishing this efficiency and time structure. This report describes the NeutronSTARS array, which was designed and commissioned during this project. It also describes the surrogate reaction technique, specifically referencing a 235U(n,2n) commissioning measurement that was fielded during the past year. Advanced multiplicity analysis techniques have been developed for this work, which should allow for efficient analysis of 241Pu(n,2n) and 239Pu(n,2n) cross section measurements« less

Review of the methods to form hydrogen peroxide in electrical discharge plasma with liquid water

NASA Astrophysics Data System (ADS)

Locke, Bruce R.; Shih, Kai-Yuan

2011-06-01

This paper presents a review of the literature dealing with the formation of hydrogen peroxide from plasma processes. Energy yields for hydrogen peroxide generation by plasma from water span approximately three orders of magnitude from 4 × 10-2 to 80 g kWh-1. A wide range of plasma processes from rf to pulsed, ac, and dc discharges directly in the liquid phase have similar energy yields and may thus be limited by radical quenching processes at the plasma-liquid interface. Reactor modification using discharges in bubbles and discharges over the liquid phase can provide modest improvements in energy yield over direct discharge in the liquid, but the interpretation is complicated by additional chemical reactions of gas phase components such as ozone and nitrogen oxides. The highest efficiency plasma process utilizes liquid water droplets that may enhance efficiency by sequestering hydrogen peroxide in the liquid and by suppressing decomposition reactions by radicals from the gas and at the interface. Kinetic simulations of water vapor reported in the literature suggest that plasma generation of hydrogen peroxide should approach 45% of the thermodynamics limit, and this fact coupled with experimental studies demonstrating improvements with the presence of the condensed liquid phase suggest that further improvements in energy yield may be possible. Plasma generation of hydrogen peroxide directly from water compares favorably with a number of other methods including electron beam, ultrasound, electrochemical and photochemical methods, and other chemical processes.

On the ambiguity of the reaction rate constants in multivariate curve resolution for reversible first-order reaction systems.

PubMed

Schröder, Henning; Sawall, Mathias; Kubis, Christoph; Selent, Detlef; Hess, Dieter; Franke, Robert; Börner, Armin; Neymeyr, Klaus

2016-07-13

If for a chemical reaction with a known reaction mechanism the concentration profiles are accessible only for certain species, e.g. only for the main product, then often the reaction rate constants cannot uniquely be determined from the concentration data. This is a well-known fact which includes the so-called slow-fast ambiguity. This work combines the question of unique or non-unique reaction rate constants with factor analytic methods of chemometrics. The idea is to reduce the rotational ambiguity of pure component factorizations by considering only those concentration factors which are possible solutions of the kinetic equations for a properly adapted set of reaction rate constants. The resulting set of reaction rate constants corresponds to those solutions of the rate equations which appear as feasible factors in a pure component factorization. The new analysis of the ambiguity of reaction rate constants extends recent research activities on the Area of Feasible Solutions (AFS). The consistency with a given chemical reaction scheme is shown to be a valuable tool in order to reduce the AFS. The new methods are applied to model and experimental data. Copyright © 2016 Elsevier B.V. All rights reserved.

The Pathway of Oligomeric DNA Melting Investigated by Molecular Dynamics Simulations

PubMed Central

Wong, Ka-Yiu; Pettitt, B. Montgomery

2008-01-01

Details of the reaction coordinate for DNA melting are fundamental to much of biology and biotechnology. Recently, it has been shown experimentally that there are at least three states involved. To clarify the reaction mechanism of the melting transition of DNA, we perform 100-ns molecular dynamics simulations of a homo-oligomeric, 12-basepair DNA duplex, d(A12)·d(T12), with explicit salt water at 400 K. Analysis of the trajectory reveals the various biochemically important processes that occur on different timescales. Peeling (including fraying from the ends), searching for Watson-Crick complements, and dissociation are recognizable processes. However, we find that basepair searching for Watson-Crick complements along a strand is not mechanistically tied to or directly accessible from the dissociation steps of strand melting. A three-step melting mechanism is proposed where the untwisting of the duplex is determined to be the major component of the reaction coordinate at the barrier. Though the observations are limited to the characteristics of the system being studied, they provide important insight into the mechanism of melting of other more biologically relevant forms of DNA, which will certainly differ in details from those here. PMID:18952784

Radiation chemical studies of Gly-Met-Gly in aqueous solution

DOE PAGES

Barata-Vallejo, Sebastian; Ferreri, Carla; Zhang, Tao; ...

2016-10-25

Important biological consequences are related to the reaction of HO radicals with methionine (Met). Several fundamental aspects remain to be defined when Met is an amino acid residue incorporated in the interior of peptides and proteins. The present study focuses on Gly-Met-Gly, the simplest peptide where Met is not a terminal residue. The reactions of HO with Gly-Met-Gly and its N-acetyl derivative were studied by pulse radiolysis technique. The transient absorption spectra were resolved into contributions from specific components of radical intermediates. Moreover, a detailed product analysis is provided for the first time for Met-containing peptides in radiolytic studies tomore » support the mechanistic proposal. By parallel radiolytical and electrochemical reactions and consequent product identification, the formation of sulfoxide attributed to the direct HO radical attack on the sulfide functionality of the Met residue could be excluded, with the in situ generated hydrogen peroxide responsible for this oxidation. LC–MS and high resolution MS/MS were powerful analytical tools to envisage the structures of five products, thus allowing to complete the mechanistic picture of the overall Met-containing peptide reactivity.« less

Simulation of Reacting Flow with a Discontinuous Spectral Element Method

NASA Astrophysics Data System (ADS)

Ghiasi, Zia; Mashayek, Farzad; Komperda, Jonathan

2013-11-01

While using high order methods is desirable in order to accurately capture the small scale mixing effects in reacting flows, the challenge is to develop and implement such methods for complex geometries. In this work, a high-order Discontinuous Spectral Element Method (DSEM) code, which solves for the Navier-Stokes equations, has been modified by adding the appropriate components to solve for scalar transport equations in order to simulate the chemical reaction. Dealing with discontinuous solution at element interfaces is a challenge that is met by patching the fluxes at mortars thus making them continuous on interfaces. The patching is performed using the Lax-Fredrichs numerical flux for scalars, whereas a generalized Riemann solver is used for the Navier-Stokes equations. Direct numerical simulation is conducted in a temporally developing mixing layer to validate the method for a single step reaction (F + rO --> [ 1 + r ] P). Next, the method is implemented to simulate a subsonic reacting flow in a slanted cavity combustor with gaseous fuel injectors to demonstrate the capability of the method to handle complex geometries. The results will be used for physical understanding of mixing and reaction in this type of combustors.

New directions in diagnostic evaluation of insect allergy.

PubMed

Golden, David B K

2014-08-01

Diagnosis of insect sting allergy and prediction of risk of sting anaphylaxis are often difficult because tests for venom-specific IgE antibodies have a limited positive predictive value and do not reliably predict the severity of sting reactions. Component-resolved diagnosis using recombinant venom allergens has shown promise in improving the specificity of diagnostic testing for insect sting allergy. Basophil activation tests have been explored as more sensitive assays for identification of patients with insect allergy and for prediction of clinical outcomes. Measurement of mast cell mediators reflects the underlying risk for more severe reactions and limited clinical response to treatment. Measurement of IgE to recombinant venom allergens can distinguish cross-sensitization from dual sensitization to honeybee and vespid venoms, thus helping to limit venom immunotherapy to a single venom instead of multiple venoms in many patients. Basophil activation tests can detect venom allergy in patients who show no detectable venom-specific IgE in standard diagnostic tests and can predict increased risk of systemic reactions to venom immunotherapy, and to stings during and after stopping venom immunotherapy. The risk of severe or fatal anaphylaxis to stings can also be predicted by measurement of baseline serum tryptase or other mast cell mediators.

MICROWAVE-FACILITATED MULTICOMPONENT REACTIONS UNDER SOLVENT-FREE CONDITIONS

EPA Science Inventory

The application of microwave-expedited solvent-free synthetic protocols in multi-component (MCC) reactions will be exemplified by several condensation and cyclization reactions including the rapid one-pot assembly of heterocyclic compounds from in situ generated intermediates. R...

Load compensating reactions to perturbations at wrist joint in normal man

NASA Technical Reports Server (NTRS)

Jaeger, R. J.; Agarwell, G. C.; Gottlieb, G. L.

1981-01-01

The electromyographic responses to step torque loads were studied in flexors and extensors at the human wrist. Based on temporal bursting patterns and functional behavior, the response was divided into four temporal components. Two early components, the myotatic (30-60 ms) late myotatic (60-120 ms) appears to be reflex response. The third postmyotatic component (120-200 ms) appear to be a triggered reaction, preceeding the fourth, stabilizing component (200-400 ms). A comparison of response at the wrist with similar data at the ankle provides the basis for a generalized classification of the response in various muscles to torque step perturbations.

The Fixed-Links Model in Combination with the Polynomial Function as a Tool for Investigating Choice Reaction Time Data

ERIC Educational Resources Information Center

Schweizer, Karl

2006-01-01

A model with fixed relations between manifest and latent variables is presented for investigating choice reaction time data. The numbers for fixation originate from the polynomial function. Two options are considered: the component-based (1 latent variable for each component of the polynomial function) and composite-based options (1 latent…

14 CFR 23.499 - Supplementary conditions for nose wheels.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., the application of 1.33 times the full steering torque combined with a vertical reaction equal to 1.33 times the maximum static reaction on the nose gear must be assumed. However, if a torque limiting device... components at the axle must be— (1) A vertical component of 2.25 times the static load on the wheel; and (2...

14 CFR 23.499 - Supplementary conditions for nose wheels.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., the application of 1.33 times the full steering torque combined with a vertical reaction equal to 1.33 times the maximum static reaction on the nose gear must be assumed. However, if a torque limiting device... components at the axle must be— (1) A vertical component of 2.25 times the static load on the wheel; and (2...

14 CFR 23.499 - Supplementary conditions for nose wheels.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., the application of 1.33 times the full steering torque combined with a vertical reaction equal to 1.33 times the maximum static reaction on the nose gear must be assumed. However, if a torque limiting device... components at the axle must be— (1) A vertical component of 2.25 times the static load on the wheel; and (2...

Command module/service module reaction control subsystem assessment

NASA Technical Reports Server (NTRS)

Weary, D. P.

1971-01-01

Detailed review of component failure histories, qualification adequacy, manufacturing flow, checkout requirements and flow, ground support equipment interfaces, subsystem interface verification, protective devices, and component design did not reveal major weaknesses in the command service module (CSM) reaction control system (RCS). No changes to the CSM RCS were recommended. The assessment reaffirmed the adequacy of the CSM RCS for future Apollo missions.

OSP Parameters and the Cognitive Component of Reaction Time to a Missing Stimulus: Linking Brain and Behavior

ERIC Educational Resources Information Center

Hernandez, Oscar H.; Vogel-Sprott, Muriel

2009-01-01

This within-subjects experiment tested the relationship between the premotor (cognitive) component of reaction time (RT) to a missing stimulus and parameters of the omitted stimulus potential (OSP) brain wave. Healthy young men (N = 28) completed trials with an auditory stimulus that recurred at 2 s intervals and ceased unpredictably. Premotor RT…

Efficient Three-Component Strecker Reaction of Aldehydes/Ketones via NHC-Amidate Palladium(II) Complex Catalysis

PubMed Central

Jarusiewicz, Jamie; Choe, Yvonne; Yoo, Kyung Soo; Park, Chan Pil

2009-01-01

A simple and efficient one-pot three-component method has been developed for the synthesis of α-aminonitriles. This Strecker reaction is applicable for aldehydes and ketones with aliphatic or aromatic amines and trimethyl siliyl cyanide in the presence of a palladium Lewis aid catalyst in dichloromethane solvent at room temperature. PMID:19265413

Core-level photoemission investigation of atomic-fluorine adsorption on GaAs(110)

NASA Astrophysics Data System (ADS)

McLean, A. B.; Terminello, L. J.; McFeely, F. R.

1989-12-01

The adsorption of atomic F on the cleaved GaAs(110) surface has been studied with use of high-resolution core-level photoelectron spectroscopy by exposing the GaAs(110) surfaces to XeF2, which adsorbs dissociatively, leaving atomic F behind. This surface reaction produces two chemically shifted components in the Ga 3d core-level emission which are attributed to an interfacial monofluoride and a stable trifluoride reaction product, respectively. The As 3d core level develops only one chemically shifted component and from its exposure-dependent behavior it is attributed to an interfacial monofluoride. Least-squares analysis of the core-level line shapes revealed that (i) the F bonds to both the anion and the cation , (ii) the GaF3 component (characteristic of strong interfacial reaction) and the surface core-level shifted component (characteristic of a well ordered, atomically clean surface) are present together over a relatively large range of XeF2 exposures, and (iii) it is the initial disruption of the GaAs(110) surface that is the rate-limiting step in this surface reaction. These results are compared with similar studies of Cl and O adsorption on GaAs(110).

The Experimental Study of Nuclear Astrophysics Reaction Rate of 93Zr(n,γ)94Zr

NASA Astrophysics Data System (ADS)

Gan, L.; Li, Z. H.; Su, J.; Yan, S. Q.; Guo, B.; Du, X. C.; Wu, Z. D.; Zeng, S.; Jin, S. J.; Wang, Y. B.; Bai, X. X.; Zhang, W. J.; Sun, H. B.; Li, E. T.

The slow neutron capture (s-) process plays a very important role in the nucleosynthesis, which produces about half of the elements heavier than iron. 94Zr is mainly from 93Zr(n,γ)94Zr in the s-process, and the direct component of the 93Zr(n,γ)94Zr capture reaction can be derived from the neutron spectroscopic factor of 94Zr. As the existing neutron spectroscopic factors of 94Zr vary from each other up to 60%, a new work should be adopted to measure it exactly. In the present work, the angular distributions of 94Zr(13C,13C)94Zr, 94Zr(12C,12C)94Zr and 94Zr(12C,13C)93Zr were obtained using the highprecision Q3D magnetic spectrograph. In addition, distorted-wave Born approximation (DWBA) calculations of the transfer differential cross sections were performed. The calculated result displays a good agreement with the experiment data, and a value of 2.60±0.20 for the neutron spectroscopic factor of 94Zr was extracted, and the direct capture cross section versus neutron energy of 93Zr(n,γ)94Zr for the ground state of 94Zr was obtained too.

Single tube genotyping of sickle cell anaemia using PCR-based SNP analysis

PubMed Central

Waterfall, Christy M.; Cobb, Benjamin D.

2001-01-01

Allele-specific amplification (ASA) is a generally applicable technique for the detection of known single nucleotide polymorphisms (SNPs), deletions, insertions and other sequence variations. Conventionally, two reactions are required to determine the zygosity of DNA in a two-allele system, along with significant upstream optimisation to define the specific test conditions. Here, we combine single tube bi-directional ASA with a ‘matrix-based’ optimisation strategy, speeding up the whole process in a reduced reaction set. We use sickle cell anaemia as our model SNP system, a genetic disease that is currently screened using ASA methods. Discriminatory conditions were rapidly optimised enabling the unambiguous identification of DNA from homozygous sickle cell patients (HbS/S), heterozygous carriers (HbA/S) or normal DNA in a single tube. Simple downstream mathematical analyses based on product yield across the optimisation set allow an insight into the important aspects of priming competition and component interactions in this competitive PCR. This strategy can be applied to any polymorphism, defining specific conditions using a multifactorial approach. The inherent simplicity and low cost of this PCR-based method validates bi-directional ASA as an effective tool in future clinical screening and pharmacogenomic research where more expensive fluorescence-based approaches may not be desirable. PMID:11726702

Single tube genotyping of sickle cell anaemia using PCR-based SNP analysis.

PubMed

Waterfall, C M; Cobb, B D

2001-12-01

Allele-specific amplification (ASA) is a generally applicable technique for the detection of known single nucleotide polymorphisms (SNPs), deletions, insertions and other sequence variations. Conventionally, two reactions are required to determine the zygosity of DNA in a two-allele system, along with significant upstream optimisation to define the specific test conditions. Here, we combine single tube bi-directional ASA with a 'matrix-based' optimisation strategy, speeding up the whole process in a reduced reaction set. We use sickle cell anaemia as our model SNP system, a genetic disease that is currently screened using ASA methods. Discriminatory conditions were rapidly optimised enabling the unambiguous identification of DNA from homozygous sickle cell patients (HbS/S), heterozygous carriers (HbA/S) or normal DNA in a single tube. Simple downstream mathematical analyses based on product yield across the optimisation set allow an insight into the important aspects of priming competition and component interactions in this competitive PCR. This strategy can be applied to any polymorphism, defining specific conditions using a multifactorial approach. The inherent simplicity and low cost of this PCR-based method validates bi-directional ASA as an effective tool in future clinical screening and pharmacogenomic research where more expensive fluorescence-based approaches may not be desirable.

Development of a Vsible-Light-Active Film for Direct Solar Energy Storage

NASA Astrophysics Data System (ADS)

Salazar, Audrey

We conceived of a two-compartment photocatalytic assembly for direct storage of solar energy as chemical potential. Our approach was to maintain reductant and oxidant in separate compartments and develop a visible light (wavelength >400nm) photo-active film to effect an uphill photoreaction between compartments. A proton exchange membrane was included in the assembly to complete the electrical circuit. Towards obtaining a working prototype of the assembly, we developed a freeze-drying method to adhere visible-light photoactive nanoparticles to a self- standing, non-porous and conductive indium tin oxide-polyvinylidene difluoride (ITO-PVDF) support film, developed in-house. We explored the possibility of employing an iron-rich metal oxide as the photocatalytic component of the film and several were explored utilizing the sodium tartrate-assisted photoreduction of Cr(VI) to Cr(III). Although the Fe2O3-coated TiO2 nanoparticles were active for photoreduction, the initial reaction rate was modest and was slowed by substantial deactivation, making it unsuitable as a photo-active material for the composite film. A complete, two-compartment assembly was prepared using cadmium sulfide (CdS) and preliminarily examined for the Cr(VI) probe reaction, however, no catalytic activity was observed. To identify the reason(s) for this observation, further testing of the apparatus and the composite film is required.

Simultaneous determination of main reaction components in the reaction mixture during biodiesel production.

PubMed

Sánek, Lubomír; Pecha, Jiří; Kolomazník, Karel

2013-03-01

The proposed analytical method allows for simultaneous determination by GC using a programed temperature vaporization injector and a flame ionization detector of the main reaction components (i.e. glycerol, methyl esters, mono-, di-, and triacylglycerols) in the reaction mixture during biodiesel production. The suggested method is convenient for the rapid and simple evaluation of the kinetic data gained during the transesterification reaction and, also partially serves as an indicator of the quality of biodiesel and mainly, as the indicator of the efficiency of the whole production process (i.e. the conversion of triacylglycerols to biodiesel and its time progress). The optimization of chromatographic conditions (e.g. the oven temperature program, injector setting, amount of derivatization reagent, and the derivatization reaction time) was performed. The method has been validated with crude samples of biodiesel made from waste-cooking oils in terms of linearity, precision, accuracy, sensitivity, and limits of detection and quantification. The results confirmed a satisfactory degree of accuracy and repeatability (the mean RSDs were usually below 2%) necessary for the reliable quantitative determination of all components in the considerable concentration range (e.g. 10-1100 μg/mL in case of methyl esters). Compound recoveries ranging from 96 to 104% were obtained. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-Relevance Appraisal Influences Facial Reactions to Emotional Body Expressions

PubMed Central

Grèzes, Julie; Philip, Léonor; Chadwick, Michèle; Dezecache, Guillaume; Soussignan, Robert; Conty, Laurence

2013-01-01

People display facial reactions when exposed to others' emotional expressions, but exactly what mechanism mediates these facial reactions remains a debated issue. In this study, we manipulated two critical perceptual features that contribute to determining the significance of others' emotional expressions: the direction of attention (toward or away from the observer) and the intensity of the emotional display. Electromyographic activity over the corrugator muscle was recorded while participants observed videos of neutral to angry body expressions. Self-directed bodies induced greater corrugator activity than other-directed bodies; additionally corrugator activity was only influenced by the intensity of anger expresssed by self-directed bodies. These data support the hypothesis that rapid facial reactions are the outcome of self-relevant emotional processing. PMID:23405230

Temporal Frequency Modulates Reaction Time Responses to First-Order and Second-Order Motion

ERIC Educational Resources Information Center

Hutchinson, Claire V.; Ledgeway, Tim

2010-01-01

This study investigated the effect of temporal frequency and modulation depth on reaction times for discriminating the direction of first-order (luminance-defined) and second-order (contrast-defined) motion, equated for visibility using equal multiples of direction-discrimination threshold. Results showed that reaction times were heavily…

In situ X-ray diffraction analysis of (CF x) n batteries: signal extraction by multivariate analysis

DOE PAGES

Rodriguez, Mark A.; Keenan, Michael R.; Nagasubramanian, Ganesan

2007-11-10

In this study, (CF x) n cathode reaction during discharge has been investigated using in situ X-ray diffraction (XRD). Mathematical treatment of the in situ XRD data set was performed using multivariate curve resolution with alternating least squares (MCR–ALS), a technique of multivariate analysis. MCR–ALS analysis successfully separated the relatively weak XRD signal intensity due to the chemical reaction from the other inert cell component signals. The resulting dynamic reaction component revealed the loss of (CF x) n cathode signal together with the simultaneous appearance of LiF by-product intensity. Careful examination of the XRD data set revealed an additional dynamicmore » component which may be associated with the formation of an intermediate compound during the discharge process.« less

Determination of the fluxes in the central metabolism of Corynebacterium glutamicum by nuclear magnetic resonance spectroscopy combined with metabolite balancing.

PubMed

Marx, A; de Graaf, A A; Wiechert, W; Eggeling, L; Sahm, H

1996-01-20

To determine the in vivo fluxes of the central metabolism we have developed a comprehensive approach exclusively based on the fundamental enzyme reactions known to be present, the fate of the carbon atoms of individual reactions, and the metabolite balance of the culture. No information on the energy balance is required, nor information on enzyme activities, or the directionalities of reactions. Our approach combines the power of (1)H-detected (13)C nuclear magnetic resonance spectroscopy to follow individual carbons with the simplicity of establishing carbon balances of bacterial cultures. We grew a lysine-producing strain of Corynebacterium glutamicum to the metabolic and isotopic steady state with [1-(13)C]glucose and determined the fractional enrichments in 27 carbon atoms of 11 amino acids isolated from the cell. Since precursor metabolites of the central metabolism are incorporated in an exactly defined manner in the carbon skeleton of amino acids, the fractional enrichments in carbons of precursor metabolites (oxaloacetate, glyceraldehyde 3-phosphate, erythrose 4-phosphate, etc.) became directly accessible. A concise and generally applicable mathematical model was established using matrix calculus to express all metabolite mass and carbon labeling balances. An appropriate all-purpose software for the iterative solution of the equations is supplied. Applying this comprehensive methodology to C. glutamicum, all major fluxes within the central metabolism were determined. The result is that the flux through the pentose phosphate pathway is 66.4% (relative to the glucose input flux of 1.49 mmol/g dry weight h), that of entry into the tricarboxylic acid cycle 62.2%, and the contribution of the succinylase pathway of lysine synthesis 13.7%. Due to the large amount and high quality of measured data in vivo exchange reactions could also be quantitated with particularly high exchange rates within the pentose phosphate pathway for the ribose 5-phosphate transketolase reaction. Moreover, the total net flux of the anaplerotic reactions was quantitated as 38.0%. Most importantly, we found that in vivo one component within these anaplerotic reactions is a back flux from the carbon 4 units of the tricarboxylic acid cycle to the carbon 3 units of glycolysis of 30.6%. (c) 1996 John Wiley & Sons, Inc.

Controlling First-Row Catalysts: Amination of Aryl and Heteroaryl Chlorides and Bromides with Primary Aliphatic Amines Catalyzed by a BINAP-Ligated Single-Component Ni(0) Complex

PubMed Central

2015-01-01

First-row metal complexes often undergo undesirable one-electron redox processes during two-electron steps of catalytic cycles. We report the amination of aryl chlorides and bromides with primary aliphatic amines catalyzed by a well-defined, single-component nickel precursor (BINAP)Ni(η2-NC-Ph) (BINAP = 2,2′-bis(biphenylphosphino)-1,1′-binaphthalene) that minimizes the formation of Ni(I) species and (BINAP)2Ni. The scope of the reaction encompasses electronically varied aryl chlorides and nitrogen-containing heteroaryl chlorides, including pyridine, quinoline, and isoquinoline derivatives. Mechanistic studies support the catalytic cycle involving a Ni(0)/Ni(II) couple for this nickel-catalyzed amination and are inconsistent with a Ni(I) halide intermediate. Monitoring the reaction mixture by 31P NMR spectroscopy identified (BINAP)Ni(η2-NC-Ph) as the resting state of the catalyst in the amination of both aryl chlorides and bromides. Kinetic studies showed that the amination of aryl chlorides and bromides is first order in both catalyst and aryl halide and zero order in base and amine. The reaction of a representative aryl chloride is inverse first order in PhCN, but the reaction of a representative aryl bromide is zero order in PhCN. This difference in the order of the reaction in PhCN indicates that the aryl chloride reacts with (BINAP)Ni(0), formed by dissociation PhCN from (BINAP)Ni(η2-NC-Ph), but the aryl bromide directly reacts with (BINAP)Ni(η2-NC-Ph). The overall kinetic behavior is consistent with turnover-limiting oxidative addition of the aryl halide to Ni(0). Several pathways for catalyst decomposition were identified, such as the formation of the catalytically inactive bis(amine)-ligated arylnickel(II) chloride, (BINAP)2Ni(0), and the Ni(I) species [(BINAP)Ni(μ-Cl)]2. By using a well-defined nickel complex as catalyst, the formation of (BINAP)2Ni(0) is avoided and the formation of the Ni(I) species [(BINAP)Ni(μ-Cl)]2 is minimized. PMID:24397570

Application of direct thermometric analysis in iodometry.

PubMed

Marik-Korda, P; Erdey, L

1970-12-01

Elementary chlorine was determined by a thermometric method using potassium iodide as reagent. The temperature rise corresponding to the heat of reaction was proportional to the chlorine content. Iodine formed in the reaction was also determined with sodium thiosulphate. The heat of the chlorine-iodide reaction is about five times that of the iodine-thiosulphate reaction. Direct determination with potassium iodide is simpler and more rapid than the indirect one.

Scaling-Up Solid Oxide Membrane Electrolysis Technology for Magnesium Production

NASA Astrophysics Data System (ADS)

Pati, Soobhankar; Powell, Adam; Tucker, Steve; Derezinski, Steve

Metal Oxygen Separation Technologies, Inc. (MOxST) is actively developing Solid Oxide Membrane (SOM) electrolysis technology for production of magnesium directly from its oxide. The vital component of this technology is the oxygen ion-conducting solid zirconia electrolyte separating the molten flux (a mixture of salts and oxide) and the inert anode. The zirconia not only protects the anode from the flux but also prevents anode gas back-reaction, increasing the efficiency. This makes it possible to produce low-cost high-purity magnesium and high-purity oxygen as a byproduct with no direct greenhouse gas emissions. In this paper we discuss the design modifications made to address the scaling-up challenges, particularly for producing magnesium in liquid form. The key accomplishment to date is the successful development of a prototype capable of producing few kilograms of magnesium per day. We will also describe the prerequisite properties of an inert anode and suitable materials for the same.

Optimum concentration gradient of the electrocatalyst, Nafion® and poly(tetrafluoroethylene) in a membrane-electrode-assembly for enhanced performance of direct methanol fuel cells.

PubMed

Liu, Jing Hua; Jeon, Min Ku; Lee, Ki Rak; Woo, Seong Ihl

2010-12-14

A combinatorial library of membrane-electrode-assemblies (MEAs) which consisted of 27 different compositions was fabricated to optimize the multilayer structure of direct methanol fuel cells. Each spot consisted of three layers of ink and a gradient was generated by employing different concentrations of the three components (Pt catalyst, Nafion® and polytetrafluoroethylene (PTFE)) of each layer. For quick evaluation of the library, a high-throughput optical screening technique was employed for methanol electro-oxidation reaction (MOR) activity. The screening results revealed that gradient layers could lead to higher MOR activity than uniform layers. It was found that the MOR activity was higher when the concentrations of Pt catalyst and Nafion ionomer decreased downward from the top layer to the bottom layer. On the other hand, higher MOR activity was observed when PTFE concentration increased downward from the top to the bottom layer.

Exploring the hidden interior of the Earth with directional neutrino measurements.

PubMed

Leyton, Michael; Dye, Stephen; Monroe, Jocelyn

2017-07-10

Roughly 40% of the Earth's total heat flow is powered by radioactive decays in the crust and mantle. Geo-neutrinos produced by these decays provide important clues about the origin, formation and thermal evolution of our planet, as well as the composition of its interior. Previous measurements of geo-neutrinos have all relied on the detection of inverse beta decay reactions, which are insensitive to the contribution from potassium and do not provide model-independent information about the spatial distribution of geo-neutrino sources within the Earth. Here we present a method for measuring previously unresolved components of Earth's radiogenic heating using neutrino-electron elastic scattering and low-background, direction-sensitive tracking detectors. We calculate the exposures needed to probe various contributions to the total geo-neutrino flux, specifically those associated to potassium, the mantle and the core. The measurements proposed here chart a course for pioneering exploration of the veiled inner workings of the Earth.

Multi-component removal in flue gas by aqua ammonia

DOEpatents

Yeh, James T [Bethel Park, PA; Pennline, Henry W [Bethel Park, PA

2007-08-14

A new method for the removal of environmental compounds from gaseous streams, in particular, flue gas streams. The new method involves first oxidizing some or all of the acid anhydrides contained in the gas stream such as sulfur dioxide (SO.sub.2) and nitric oxide (NO) and nitrous oxide (N.sub.2O) to sulfur trioxide (SO.sub.3) and nitrogen dioxide (NO.sub.2). The gas stream is subsequently treated with aqua ammonia or ammonium hydroxide which captures the compounds via chemical absorption through acid-base or neutralization reactions. The products of the reactions can be collected as slurries, dewatered, and dried for use as fertilizers, or once the slurries have been dewatered, used directly as fertilizers. The ammonium hydroxide can be regenerated and recycled for use via thermal decomposition of ammonium bicarbonate, one of the products formed. There are alternative embodiments which entail stoichiometric scrubbing of nitrogen oxides and sulfur oxides with subsequent separate scrubbing of carbon dioxide.

Beamed neutron emission driven by laser accelerated light ions

NASA Astrophysics Data System (ADS)

Kar, S.; Green, A.; Ahmed, H.; Alejo, A.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; Mirfayzi, S. R.; McKenna, P.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.

2016-05-01

Highly anisotropic, beam-like neutron emission with peak flux of the order of 109 n/sr was obtained from light nuclei reactions in a pitcher-catcher scenario, by employing MeV ions driven by a sub-petawatt laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ˜ 70^\\circ , with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitcher-catcher materials indicates the dominant reactions being d(p, n+p)1H and d(d,n)3He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons’ spatial and spectral profiles is most likely related to the directionality and high energy of the projectile ions.

The degradation of wheat straw lignin

NASA Astrophysics Data System (ADS)

Liang, Jiaqi

2017-03-01

Lignin is a kind of formed by polymerization of aromatic alcohol, prices are lower and sources of renewable resources. Using lignin as raw material, through the push to resolve together preparation phenolic high value-added fine chemicals alkanes and aromatic hydrocarbons, such as the high grade biofuels, can partly replace fossil fuels as raw material to the production process, biomass resources is an important part of the comprehensive utilization of effective components. In lignin push solve clustering method, catalytic hydrogenolysis can directly to the lignin into liquid fuels, low oxygen content in the use of biofuels shows great potential. In this paper, through the optimization of the reaction time, reaction temperature, catalyst type and solvent type, dosage of catalyst, etc factors, determines the alcoholysis - hydrogen solution two-step degradation of lignin, the optimal process conditions: lignin alcoholysis under 50% methanol and NaOH catalyst in the solution, the lignin in methanol solution and 50% hydrogen solution under the Pd/C catalyst. In this process, the degradation of lignin yield can reach 42%.

Simultaneous quantification of alternatively spliced transcripts in a single droplet digital PCR reaction.

PubMed

Sun, Bing; Tao, Lian; Zheng, Yun-Ling

2014-06-01

Human telomerase reverse transcriptase (hTERT) is an essential component required for telomerase activity and telomere maintenance. Several alternatively spliced forms of hTERT mRNA have been reported in human primary and tumor cells. Currently, however, there is no sensitive and accurate method for the simultaneous quantification of multiple alternatively spliced RNA transcripts, such as in the case of hTERT. Here we show droplet digital PCR (ddPCR) provides sensitive, simultaneous digital quantification in a single reaction of two alternatively spliced single deletion hTERT transcripts (α-/β+ and α+/β-) as well as the opportunity to manually quantify non-deletion (α+/β+) and double deletion (α-/β-) transcripts. Our ddPCR method enables direct comparison among four alternatively spliced mRNAs without the need for internal standards or multiple primer pairs specific for each variant as real-time PCR (qPCR) requires, thus eliminating potential variation due to differences in PCR amplification efficiency.

[The genetic determination and function of RR-proteins--the regulators of photoperiodic reaction and circadian rhythms in plants].

PubMed

Tots'kyĭ, V M; D'iachenko, L F; Muterko, O F; Balashova, I A; Toptikov, V A

2012-01-01

The present review devoted to the analysis of recent literature on genetic determination and the domain organization of the newly discovered two-component signaling systems in pro- and eukaryotes. These structures are involved in the regulation of numerous morphological and physiological processes in plants. RR-proteins, it the key elements of signaling systems, they launch a cascade of phosphotransferase reactions and directly or indirectly regulate the transcription and activity other proteins, including enzymes, in response to hormones or environmental factors. Modern views on the molecular and genetic mechanisms of photoperiodic response, circadian rhythms and anti-stress responses in plants are set out in these positions. The relationship between gene expression and photoreceptor sensitivity of plants to photoperiod traced. We present our own data obtained on the isogenic lines of wheat, where been showed dependence expression of structural genes of enzymes on the allelic composition of individual PRR-loci and the duration action of low temperature.

Growing Platinum-Ruthenium-Tin ternary alloy nanoparticles on reduced graphene oxide for strong ligand effect toward enhanced ethanol oxidation reaction.

PubMed

Xia, Qing Qing; Zhang, Lian Ying; Zhao, Zhi Liang; Li, Chang Ming

2017-11-15

Uniform Pt 1 Ru 0.5 Sn 0.5 ternary alloy nanoparticles are in situ deposited on reduced graphene oxide (Pt 1 Ru 0.5 Sn 0.5 -RGO) through its functional groups and defects as nucleation sites to greatly electrocatalyze ethanol oxidation reaction for much higher mass current densities, larger apparent specific current densities and better stability than commercial Pt-C catalyst (Pt-C(commer)). Mechanistic studies indicate that the excellent electrocatalytic activity and anti-poisoning are resulted from a strong ligand effect of the ternary alloy components, in which the charge transfer is boosted while decreasing the density of states close to the Fermi level of Pt to reduce bond energy between Pt and CO-like adsorbates for greatly improved anti-poisoning ability. This work holds a great promise to fabricate a high performance anode catalyst with a low Pt loading for direct ethanol fuel cells. Copyright © 2017. Published by Elsevier Inc.

Testing asymmetries in noncognate translation priming: Evidence from RTs and ERPs

PubMed Central

SCHOONBAERT, SOFIE; HOLCOMB, PHILLIP J.; GRAINGER, JONATHAN; HARTSUIKER, ROBERT J.

2012-01-01

In this study, English–French bilinguals performed a lexical decision task while reaction times (RTs) and event related potentials (ERPs) were measured to L2 targets, preceded by noncognate L1 translation primes versus L1 unrelated primes (Experiment 1a) and vice versa (Experiment 1b). The prime–target stimulus onset asynchrony was 120 ms. Significant masked translation priming was observed, indicated by faster reaction times and a decreased N400 for translation pairs as opposed to unrelated pairs, both from L1 to L2 (Experiment 1a) and from L2 to L1 (Experiment 1b), with the latter effect being weaker (RTs) and less longer lasting (ERPs). A translation priming effect was also found in the N250 ERP component, and this effect was stronger and earlier in the L2 to L1 priming direction than the reverse. The results are discussed with respect to possible mechanisms at the basis of asymmetric translation priming effects in bilinguals. PMID:20557483

Children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia: A randomized controlled trial.

PubMed

Bagherian, Ali; Sheikhfathollahi, Mahmood

2016-01-01

Topical anesthesia has been widely advocated as an important component of atraumatic administration of intraoral local anesthesia. The aim of this study was to use direct observation of children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia. Forty-eight children participated in this randomized controlled clinical trial. They received two separate inferior alveolar nerve block or primary maxillary molar infiltration injections on contralateral sides of the jaws by both cotton-roll vibration (a combination of topical anesthesia gel, cotton roll, and vibration for physical distraction) and control (routine topical anesthesia) methods. Behavioral pain reactions of children were measured according to the author-developed face, head, foot, hand, trunk, and cry (FHFHTC) scale, resulting in total scores between 0 and 18. The total scores on the FHFHTC scale ranged between 0-5 and 0-10 in the cotton-roll vibration and control methods, respectively. The mean ± standard deviation values of total scores on FHFHTC scale were lower in the cotton-roll vibration method (1.21 ± 1.38) than in control method (2.44 ± 2.18), and this was statistically significant (P < 0.001). It may be concluded that the cotton-roll vibration method can be more helpful than the routine topical anesthesia in reducing behavioral pain reactions in children during local anesthesia administration.

Revealing Brown Carbon Chromophores Produced in Reactions of Methylglyoxal with Ammonium Sulfate.

PubMed

Lin, Peng; Laskin, Julia; Nizkorodov, Sergey A; Laskin, Alexander

2015-12-15

Atmospheric brown carbon (BrC) is an important contributor to light absorption and climate forcing by aerosols. Reactions between small water-soluble carbonyls and ammonia or amines have been identified as one of the potential pathways of BrC formation. However, detailed chemical characterization of BrC chromophores has been challenging and their formation mechanisms are still poorly understood. Understanding BrC formation is impeded by the lack of suitable methods which can unravel the variability and complexity of BrC mixtures. This study applies high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) detector and high resolution mass spectrometry (HRMS) to investigate optical properties and chemical composition of individual BrC components produced through reactions of methylglyoxal (MG) and ammonium sulfate (AS), both of which are abundant in the atmospheric environment. A direct relationship between optical properties and chemical composition of 30 major BrC chromophores is established. Nearly all of these chromophores are nitrogen-containing compounds that account for >70% of the overall light absorption by the MG+AS system in the 300-500 nm range. These results suggest that reduced-nitrogen organic compounds formed in reactions between atmospheric carbonyls and ammonia/amines are important BrC chromophores. It is also demonstrated that improved separation of BrC chromophores by HPLC will significantly advance understanding of BrC chemistry.

Revealing Brown Carbon Chromophores Produced in Reactions of Methylglyoxal with Ammonium Sulfate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Peng; Laskin, Julia; Nizkorodov, Sergey A.

Atmospheric brown carbon (BrC) is an important contributor to light absorption and climate forcing by aerosols. Reactions between small water-soluble carbonyls and ammonia or amines have been identified as one of the potential pathways of BrC formation. However, detailed chemical characterization of BrC chromophores has been challenging and their formation mechanisms are still poorly understood. Understanding BrC formation is impeded by the lack of suitable methods which can unravel the variability and complexity of BrC mixtures. This study applies high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) detector and high resolution mass spectrometry (HRMS) to investigate optical propertiesmore » and chemical composition of individual BrC components produced through reactions of methylglyoxal (MG) and ammonium sulfate (AS), both of which are abundant in the atmospheric environment. A direct relationship between optical properties and chemical composition of 30 major BrC chromophores was established. Nearly all of these chromophores are nitrogen-containing compounds that account for >70% of the overall light absorption by the MG+AS system in the 300-500 nm range. These results suggest that reduced-nitrogen organic compounds formed in reactions between atmospheric carbonyls and ammonia/amines are important BrC chromophores. It is also demonstrated that improved separation of BrC chromophores by HPLC will significantly advance understanding of BrC chemistry.« less

The Nature of the Interplay among Components of Pedagogical Content Knowledge in Reaction Rate and Chemical Equilibrium Topics of Novice and Experienced Chemistry Teachers

ERIC Educational Resources Information Center

Akin, Fatma Nur; Uzuntiryaki-Kondakci, Esen

2018-01-01

We examined the interactions among pedagogical content knowledge (PCK) components of novice and experienced chemistry teachers in teaching reaction rate and chemical equilibrium topics in this qualitative multiple-case design study. For this aim, three chemistry teachers who had different levels of teaching experience in chemistry teaching were…

Synthesis, molecular docking and biological evaluation as HDAC inhibitors of cyclopeptide mimetics by a tandem three-component reaction and intramolecular [3+2] cycloaddition.

PubMed

Pirali, Tracey; Faccio, Valeria; Mossetti, Riccardo; Grolla, Ambra A; Di Micco, Simone; Bifulco, Giuseppe; Genazzani, Armando A; Tron, Gian Cesare

2010-02-01

Novel macrocyclic peptide mimetics have been synthesized by exploiting a three-component reaction and an azide-alkyne [3 + 2] cycloaddition. The prepared compounds were screened as HDAC inhibitors allowing us to identify a new compound with promising biological activity. In order to rationalize the biological results, computational studies have also been performed.

Linear pi-Acceptor-Templated Dynamic Clipping to Macrobicycles and[2]Rotaxanes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klivansky, Liana M.; Koshkakaryan, Gayane; Cao, Dennis

2009-04-30

Functional rotaxanes are one of the representative nanoscale molecular machines that have found applications in many areas, including molecular electronics, nanoelectromechanical systems (NEMS), photo controllable smart surfaces, and nanovalves. With the advent of molecular recognition and self-assembly, such molecular compounds can now be obtained efficiently through template-directed synthesis. One of the common strategies of making [2]rotaxanes involves the clipping of a macrocycle around a preformed dumbbell-shaped template in a [1+1] or [2+2] manner. While early examples were based on irreversible kinetic pathway through covalent bond formation, recent advances on reversible dynamic covalent chemistry (DCC) has attracted great attention to thismore » field. By virtue of thermodynamically controlled equilibria, DCC has provided highly efficient and versatile synthetic routes in the selection of specific products from a complex system. Among the several reversible reactions in the category of DCC reactions, the imine formation has proven to be very versatile in macrocyclization to give complex interlocked molecular compounds. Cryptands are three dimensional bicyclic hosts with preorganized cavities capable of inclusion of ions and small molecules. Replacing the nitrogen bridgeheads in common cryptands with aromatic ring systems gives cyclophane-based macrobicycles. The introduction of aromatic ring systems into a preorganized cage-like geometry facilitates ion-{pi} interactions and {pi}-{pi} interactions, resulting in novel metal sandwiches, fluoride receptors, and host-guest complexes. In particular, the seminal work by Gibson, Huang and coworkers on cryptand complexation with paraquat and diquat guests have resulted in the efficient synthesis of mechanically interlocked rotaxanes. The synthesis of cyclophane-based macrobicycles, however, was mostly realized through multiple reaction steps and in high-dilution conditions, which often suffered from low yield and tedious workup. Thus, a one-step, five-component [2+3] clipping reaction that can give the desired macrobicycle is highly desirable. We are motivated by a {pi}-guest templating protocol, because not only {pi}-{pi} interactions can contribute to the formation of macrobicycles, but also the resulting host-guest system holds great promise as a forerunner in the construction of interlocked molecules. (Scheme 1c) Very simple precursors, namely 1,3,5-benzenetrialdehyde (1) and 2,2{prime}-(ethylenedioxy)diethylamine (2) were chosen as the components for desired macrobicycle. (Scheme 2) The formation of six imine bonds would connect the five components to give a macrobicycle while extending the conjugation in the C{sub 3}-symmetric aromatic 'ceiling' and 'floor', which is suitable for enhancing the {pi}-{pi} interactions with a complementary aromatic template. Meanwhile, the ethylene glycol 'pillars' can provide sufficient flexibility, proper spacing, and polar binding sites to assist guest encapsulation. Initial screening of ?-templates engaged several C{sub 3} symmetric aromatic compounds in order to match the symmetry of the desired macrobicycle, which only resulted in nonspecific mixtures. It was found instead that linear bipyridinium (BPY) containing guests effectively templated the [2+3] clipping reaction. Based on this protocol, a [2]rotaxane was successfully assembled as the single product from the six-component reaction.« less

Kinetic Monte Carlo Method for Rule-based Modeling of Biochemical Networks

PubMed Central

Yang, Jin; Monine, Michael I.; Faeder, James R.; Hlavacek, William S.

2009-01-01

We present a kinetic Monte Carlo method for simulating chemical transformations specified by reaction rules, which can be viewed as generators of chemical reactions, or equivalently, definitions of reaction classes. A rule identifies the molecular components involved in a transformation, how these components change, conditions that affect whether a transformation occurs, and a rate law. The computational cost of the method, unlike conventional simulation approaches, is independent of the number of possible reactions, which need not be specified in advance or explicitly generated in a simulation. To demonstrate the method, we apply it to study the kinetics of multivalent ligand-receptor interactions. We expect the method will be useful for studying cellular signaling systems and other physical systems involving aggregation phenomena. PMID:18851068

Weak Interactions

DOE R&D Accomplishments Database

Lee, T. D.

1957-06-01

Experimental results on the non-conservation of parity and charge conservation in weak interactions are reviewed. The two-component theory of the neutrino is discussed. Lepton reactions are examined under the assumption of the law of conservation of leptons and that the neutrino is described by a two- component theory. From the results of this examination, the universal Fermi interactions are analyzed. Although reactions involving the neutrino can be described, the same is not true of reactions which do not involve the lepton, as the discussion of the decay of K mesons and hyperons shows. The question of the invariance of time reversal is next examined. (J.S.R.)

Anomalous yield reduction in direct-drive DT implosions due to 3He addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herrmann, Hans W; Langenbrunner, James R; Mack, Joseph M

2008-01-01

Glass capsules were imploded in direct drive on the OMEGA laser [T. R. Boehly et aI., Opt. Commun. 133, 495, 1997] to look for anomalous degradation in deuterium/tritium (DT) yield (i.e., beyond what is predicted) and changes in reaction history with {sup 3}He addition. Such anomalies have previously been reported for D/{sup 3}He plasmas, but had not yet been investigated for DT/{sup 3}He. Anomalies such as these provide fertile ground for furthering our physics understanding of ICF implosions and capsule performance. A relatively short laser pulse (600 ps) was used to provide some degree of temporal separation between shock andmore » compression yield components for analysis. Anomalous degradation in the compression component of yield was observed, consistent with the 'factor of two' degradation previously reported by MIT at a 50% {sup 3}He atom fraction in D{sub 2} using plastic capsules [Rygg et aI., Phys. Plasmas 13, 052702 (2006)]. However, clean calculations (i.e., no fuel-shell mixing) predict the shock component of yield quite well, contrary to the result reported by MIT, but consistent with LANL results in D{sub 2}/{sup 3}He [Wilson, et aI., lml Phys: Conf Series 112, 022015 (2008)]. X-ray imaging suggests less-than-predicted compression ofcapsules containing {sup 3}He. Leading candidate explanations are poorly understood Equation-of-State (EOS) for gas mixtures, and unanticipated particle pressure variation with increasing {sup 3}He addition.« less

Blood coagulation abnormalities in multibacillary leprosy patients.

PubMed

Silva, Débora Santos da; Teixeira, Lisandra Antonia Castro; Beghini, Daniela Gois; Ferreira, André Teixeira da Silva; Pinho, Márcia de Berredo Moreira; Rosa, Patricia Sammarco; Ribeiro, Marli Rambaldi; Freire, Monica Di Calafiori; Hacker, Mariana Andrea; Nery, José Augusto da Costa; Pessolani, Maria Cristina Vidal; Tovar, Ana Maria Freire; Sarno, Euzenir Nunes; Perales, Jonas; Bozza, Fernando Augusto; Esquenazi, Danuza; Monteiro, Robson Queiroz; Lara, Flavio Alves

2018-03-01

Leprosy is a chronic dermato-neurological disease caused by Mycobacterium leprae infection. In 2016, more than 200,000 new cases of leprosy were detected around the world, representing the most frequent cause of infectious irreversible deformities and disabilities. In the present work, we demonstrate a consistent procoagulant profile on 40 reactional and non-reactional multibacillary leprosy patients. A retrospective analysis in search of signs of coagulation abnormalities among 638 leprosy patients identified 35 leprosy patients (5.48%) which displayed a characteristic lipid-like clot formed between blood clot and serum during serum harvesting, herein named 'leprosum clot'. Most of these patients (n = 16, 45.7%) belonged to the lepromatous leprosy pole of the disease. In addition, formation of the leprosum clot was directly correlated with increased plasma levels of soluble tissue factor and von Willebrand factor. High performance thin layer chromatography demonstrated a high content of neutral lipids in the leprosum clot, and proteomic analysis demonstrated that the leprosum clot presented in these patients is highly enriched in fibrin. Remarkably, differential 2D-proteomics analysis between leprosum clots and control clots identified two proteins present only in leprosy patients clots: complement component 3 and 4 and inter-alpha-trypsin inhibitor family heavy chain-related protein (IHRP). In agreement with those observations we demonstrated that M. leprae induces hepatocytes release of IHRP in vitro. We demonstrated that leprosy MB patients develop a procoagulant status due to high levels of plasmatic fibrinogen, anti-cardiolipin antibodies, von Willebrand factor and soluble tissue factor. We propose that some of these components, fibrinogen for example, presents potential as predictive biomarkers of leprosy reactions, generating tools for earlier diagnosis and treatment of these events.

Weakly nonlinear dynamics of near-CJ detonation waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bdzil, J.B.; Klein, R.

1993-01-01

The renewed interest in safety issues for large scale industrial devices and in high speed combustion has driven recent intense efforts to gain a deeper theoretical understanding of detonation wave dynamics. Linear stability analyses, weakly nonlinear bifurcation calculations as well as full scale multi-dimensional direct numerical simulations have been pursued for a standard model problem based on the reactive Euler equations for an ideal gas with constant specific heat capacities and simplified chemical reaction models. Most of these studies are concerned with overdriven detonations. This is true despite the fact that the majority of all detonations observed in nature aremore » running at speeds close to the Chapman-Jouguet (CJ) limit value. By focusing on overdriven waves one removes an array of difficulties from the analysis that is associated with the sonic flow conditions in the wake of a CJ-detonation. In particular, the proper formulation of downstream boundary conditions in the CJ-case is a yet unsolved analytical problem. A proper treatment of perturbations in the back of a Chapman-Jouguet detonation has to account for two distinct weakly nonlinear effects in the forward acoustic wave component. The first is a nonlinear interactionof highly temperature sensitive chemistry with the forward acoustic wave component in a transonic boundary layer near the end of the reaction zone. The second is a cumulative three-wave-resonance in the sense of Majda et al. which is active in the near-sonic burnt gas flow and which is essentially independent of the details of the chemical model. In this work, we consider detonations in mixtures with moderate state sensitivity of the chemical reactions. Then, the acoustic perturbations do not influence the chemistry at the order considered and we may concentrate on the second effect; the three-wave resonance.« less

Weakly nonlinear dynamics of near-CJ detonation waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bdzil, J.B.; Klein, R.

1993-02-01

The renewed interest in safety issues for large scale industrial devices and in high speed combustion has driven recent intense efforts to gain a deeper theoretical understanding of detonation wave dynamics. Linear stability analyses, weakly nonlinear bifurcation calculations as well as full scale multi-dimensional direct numerical simulations have been pursued for a standard model problem based on the reactive Euler equations for an ideal gas with constant specific heat capacities and simplified chemical reaction models. Most of these studies are concerned with overdriven detonations. This is true despite the fact that the majority of all detonations observed in nature aremore » running at speeds close to the Chapman-Jouguet (CJ) limit value. By focusing on overdriven waves one removes an array of difficulties from the analysis that is associated with the sonic flow conditions in the wake of a CJ-detonation. In particular, the proper formulation of downstream boundary conditions in the CJ-case is a yet unsolved analytical problem. A proper treatment of perturbations in the back of a Chapman-Jouguet detonation has to account for two distinct weakly nonlinear effects in the forward acoustic wave component. The first is a nonlinear interactionof highly temperature sensitive chemistry with the forward acoustic wave component in a transonic boundary layer near the end of the reaction zone. The second is a cumulative three-wave-resonance in the sense of Majda et al. which is active in the near-sonic burnt gas flow and which is essentially independent of the details of the chemical model. In this work, we consider detonations in mixtures with moderate state sensitivity of the chemical reactions. Then, the acoustic perturbations do not influence the chemistry at the order considered and we may concentrate on the second effect; the three-wave resonance.« less

Degradation of pesticides with RSDL® (reactive skin decontamination lotion kit) lotion: LC-MS investigation.

PubMed

Fentabil, Messele; Gebremedhin, Mulu; Purdon, J Garfield; Cochrane, Laura; Goldman, Virginia Streusand

2018-09-01

This study examined the degradation of organophosphate (OP) and carbamate pesticides using RSDL ® (Reactive Skin Decontamination Lotion Kit) lotion. Degradation occurs from a nucleophilic substitution (SN) reaction between an ingredient in the RSDL lotion, potassium 2,3-butanedione monoximate (KBDO), with susceptible sites in the pesticides. Evaluation at several molar ratios of KBDO:test articles using liquid chromatography-mass spectrometry (LC-MS) techniques was performed. The OP test articles, parathion, paraoxon, parathion-methyl, paraoxon-methyl and chlorpyrifos were effectively degraded at molar ratios of four and above in less than 6min contact time. Malathion and malaoxon were similarly converted to inactive by-products at molar ratios as low as two in less than 4min. A minimum molar ratio of nine was found to be effective against the carbamate pesticide carbofuran. In the case of aldicarb, complete destruction was achieved at a molar ratio of fifteen and a reaction time of one hour. It is important to note that these studies are based on a direct liquid phase RSDL lotion reaction with the toxic chemicals without the added physical removal decontamination efficacy component provided by the sponge component of the RSDL kit. The RSDL kit is intended to be used to remove or neutralize chemical warfare agents (CWA) and T-2 toxin from the skin. In actual use, the majority of the CWA decontamination occurs through the combined action of the sponge in both removing the chemical from the skin, and in rapidly mixing the chemicals at a high molar ratio of KBDO:CWA within the pores of the sponge to enhance rapid neutralization of the chemical. Copyright © 2017 Elsevier B.V. All rights reserved.

Revisiting and Computing Reaction Coordinates with Directional Milestoning

PubMed Central

Kirmizialtin, Serdal; Elber, Ron

2011-01-01

The method of Directional Milestoning is revisited. We start from an exact and more general expression and state the conditions and validity of the memory-loss approximation. An algorithm to compute a reaction coordinate from Directional Milestoning data is presented. The reaction coordinate is calculated as a set of discrete jumps between Milestones that maximizes the flux between two stable states. As an application we consider a conformational transition in solvated Adenosine. We compare a long molecular dynamic trajectory with Directional Milestoning and discuss the differences between the maximum flux path and minimum energy coordinates. PMID:21500798

Direct Monte Carlo simulation of chemical reaction systems: Simple bimolecular reactions

NASA Astrophysics Data System (ADS)

Piersall, Shannon D.; Anderson, James B.

1991-07-01

In applications to several simple reaction systems we have explored a ``direct simulation'' method for predicting and understanding the behavior of gas phase chemical reaction systems. This Monte Carlo method, originated by Bird, has been found remarkably successful in treating a number of difficult problems in rarefied dynamics. Extension to chemical reactions offers a powerful tool for treating reaction systems with nonthermal distributions, with coupled gas-dynamic and reaction effects, with emission and adsorption of radiation, and with many other effects difficult to treat in any other way. The usual differential equations of chemical kinetics are eliminated. For a bimolecular reaction of the type A+B→C+D with a rate sufficiently low to allow a continued thermal equilibrium of reactants we find that direct simulation reproduces the expected second order kinetics. Simulations for a range of temperatures yield the activation energies expected for the reaction models specified. For faster reactions under conditions leading to a depletion of energetic reactant species, the expected slowing of reaction rates and departures from equilibrium distributions are observed. The minimum sample sizes required for adequate simulations are as low as 1000 molecules for these cases. The calculations are found to be simple and straightforward for the homogeneous systems considered. Although computation requirements may be excessively high for very slow reactions, they are reasonably low for fast reactions, for which nonequilibrium effects are most important.

In-line near-infrared (NIR) and Raman spectroscopy coupled with principal component analysis (PCA) for in situ evaluation of the transesterification reaction.

PubMed

Fontalvo-Gómez, Miriam; Colucci, José A; Velez, Natasha; Romañach, Rodolfo J

2013-10-01

Biodiesel was synthesized from different commercially available oils while in-line Raman and near-infrared (NIR) spectra were obtained simultaneously, and the spectral changes that occurred during the reaction were evaluated with principal component analysis (PCA). Raman and NIR spectra were acquired every 30 s with fiber optic probes inserted into the reaction vessel. The reaction was performed at 60-70 °C using magnetic stirring. The time of reaction was 90 min, and during this time, 180 Raman and NIR spectra were collected. NIR spectra were collected using a transflectance probe and an optical path length of 1 mm at 8 cm(-1) spectral resolution and averaging 32 scans; for Raman spectra a 3 s exposure time and three accumulations were adequate for the analysis. Raman spectroscopy showed the ester conversion as evidenced by the displacement of the C=O band from 1747 to 1744 cm(-1) and the decrease in the intensity of the 1000-1050 cm(-1) band and the 1405 cm(-1) band as methanol was consumed in the reaction. NIR spectra also showed the decrease in methanol concentration with the band in the 4750-5000 cm(-1) region; this signal is present in the spectra of the transesterification reaction but not in the neat oils. The variations in the intensity of the methanol band were a main factor in the in-line monitoring of the transesterification reaction using Raman and NIR spectroscopy. The score plot of the first principal component showed the progress of the reaction. The final product was analyzed using (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy and using mid-infrared spectroscopy, confirming the conversion of the oils to biodiesel.

The Trojan Horse method for nuclear astrophysics: Recent results for direct reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumino, A.; Gulino, M.; Spitaleri, C.

2014-05-09

The Trojan Horse method is a powerful indirect technique to determine the astrophysical factor for binary rearrangement processes A+x→b+B at astrophysical energies by measuring the cross section for the Trojan Horse (TH) reaction A+a→B+b+s in quasi free kinematics. The Trojan Horse Method has been successfully applied to many reactions of astrophysical interest, both direct and resonant. In this paper, we will focus on direct sub-processes. The theory of the THM for direct binary reactions will be shortly presented based on a few-body approach that takes into account the off-energy-shell effects and initial and final state interactions. Examples of recent resultsmore » will be presented to demonstrate how THM works experimentally.« less

Prevalence of direct-reaction mechanism in a deeply inelastic reaction, /sup 197/Au(/sup 19/F,/sup 12/B)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishihara, M.; Shimoda, T.; Froehlich, H.

1979-07-09

Continuum cross sections and spin polarizations of /sup 12/B produced in the reaction /sup 197/Au(/sup 19/F,/sup 12/B) induced by 186-MeV/sup 19/F were measured. The observed data were reproduced very well in terms of a distorted-wave Born-approximation theory, indicating that this reaction transferring as many as seven nucleons proceeds as a direct process.

Immunology of Bee Venom.

PubMed

Elieh Ali Komi, Daniel; Shafaghat, Farzaneh; Zwiener, Ricardo D

2018-06-01

Bee venom is a blend of biochemicals ranging from small peptides and enzymes to biogenic amines. It is capable of triggering severe immunologic reactions owing to its allergenic fraction. Venom components are presented to the T cells by antigen-presenting cells within the skin. These Th2 type T cells then release IL-4 and IL-13 which subsequently direct B cells to class switch to production of IgE. Generating venom-specific IgE and crosslinking FcεR1(s) on the surface of mast cells complete the sensitizing stage in allergic individuals who are most likely to experience severe and even fatal allergic reactions after being stung. Specific IgE for bee venom is a double-edged sword as it is a powerful mediator in triggering allergic events but is also applied successfully in diagnosis of the venom allergic patient. The healing capacity of bee venom has been rediscovered under laboratory-controlled conditions using animal models and cell cultures. The potential role of enzymatic fraction of bee venom including phospholipase A2 in the initiation and development of immune responses also has been studied in numerous research settings. Undoubtedly, having insights into immunologic interactions between bee venom components and innate/specific immune cells both locally and systematically will contribute to the development of immunologic strategies in specific and epitope-based immunotherapy especially in individuals with Hymenoptera venom allergy.

Isolation of recombinant antibodies directed against surface proteins of Clostridium difficile.

PubMed

Shirvan, Ali Nazari; Aitken, Robert

2016-01-01

Clostridium difficile has emerged as an increasingly important nosocomial pathogen and the prime causative agent of antibiotic-associated diarrhoea and pseudomembranous colitis in humans. In addition to toxins A and B, immunological studies using antisera from patients infected with C. difficile have shown that a number of other bacterial factors contribute to the pathogenesis, including surface proteins, which are responsible for adhesion, motility and other interactions with the human host. In this study, various clostridial targets, including FliC, FliD and cell wall protein 66, were expressed and purified. Phage antibody display yielded a large panel of specific recombinant antibodies, which were expressed, purified and characterised. Reactions of the recombinant antibodies with their targets were detected by enzyme-linked immunosorbent assay; and Western blotting suggested that linear rather than conformational epitopes were recognised. Binding of the recombinant antibodies to surface-layer proteins and their components showed strain specificity, with good recognition of proteins from C. difficile 630. However, no reaction was observed for strain R20291-a representative of the 027 ribotype. Binding of the recombinant antibodies to C. difficile M120 extracts indicated that a component of a surface-layer protein of this strain might possess immunoglobulin-binding activities. The recombinant antibodies against FliC and FliD proteins were able to inhibit bacterial motility. Copyright © 2016. Published by Elsevier Editora Ltda.

IBEX-Lo Observations of Secondary Interstellar Helium and Oxygen Distributions

NASA Astrophysics Data System (ADS)

Park, J.; Kucharek, H.; Moebius, E.; Kubiak, M. A.; Bzowski, M.; Galli, A.; McComas, D. J.

2015-12-01

Observations of the Interstellar Boundary EXplorer (IBEX) show, among other features, the pristine interstellar neutral gas flow and additional populations associated with neutral helium and oxygen. Kubiak et al. (2014, ApJS, 213, 29) discovered the "Warm Breeze", or additional He component, which is slower and warmer than the primary interstellar He population and its flow direction differs by about 19° from the interstellar neutral (ISN) flow. Park et al. (2015, ApJS, In Press) studied the combined count rate maps of heavy neutral atoms with three statistical analysis methods and found an extended tail of the ISN O flow, centered around 190° in ecliptic longitude and +15° in ecliptic latitude, or approximately 38° from the ISN O and Ne flow peak. The most likely sources for the Warm Breeze and the extended O tail may be secondary populations of interstellar He and O, created by charge exchange between ISN atoms and interstellar ions in the outer heliosheath. The charge exchange between interstellar He atoms and He+ ions is the most important reaction to generate the secondary neutral He in the outer heliosheath, with a reaction rate of 1.7×10-10 s-1 and a mean free path of ~950 AU. For O+, the charge exchange with interstellar H atoms with a rate ~1.0×10-9 s-1 and a mean free path of ~100 AU is most important. Because the differences in the reaction rates and atomic masses for He and O result in different velocity distributions in the outer heliosheath, the directional distributions of these populations at Earth orbit are not identical. In this study, we use the IBEX flux maps of the observed helium and oxygen atoms to compare their directional distributions. These observed distributions may provide constraints and information to improve our current understanding of the interactions in the outer heliosheath.

Controlled Microwave Heating Accelerates Rolling Circle Amplification

PubMed Central

Yoshimura, Takeo; Suzuki, Takamasa; Mineki, Shigeru; Ohuchi, Shokichi

2015-01-01

Rolling circle amplification (RCA) generates single-stranded DNAs or RNA, and the diverse applications of this isothermal technique range from the sensitive detection of nucleic acids to analysis of single nucleotide polymorphisms. Microwave chemistry is widely applied to increase reaction rate as well as product yield and purity. The objectives of the present research were to apply microwave heating to RCA and indicate factors that contribute to the microwave selective heating effect. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. Here, we showed that microwave-assisted RCA reactions catalyzed by either of the four thermostable DNA polymerases were accelerated over 4-folds compared with conventional RCA. Furthermore, the temperatures of the individual buffer components were specifically influenced by microwave heating. We concluded that microwave heating accelerated isothermal RCA of DNA because of the differential heating mechanisms of microwaves on the temperatures of reaction components, although the overall reaction temperatures were the same. PMID:26348227

Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

NASA Technical Reports Server (NTRS)

Scherer, N. F.; Doany, F. E.; Zewail, A. H.; Perry, J. W.

1986-01-01

Attention is given to the first results of direct, picosec measurements of the Delta-nu(OH) 5 local mode transition of H2O2. These time-resolved studies yield a direct measure of the unimolecular dissociation rate, and furnish a lower limit for the rate of energy redistribution from the OH stretch to the O-O reaction coordinate. The data thus determined may be used to ascertain the domain of validity for statistical unimolecular reaction rate theories.

Constraints on signaling network logic reveal functional subgraphs on Multiple Myeloma OMIC data.

PubMed

Miannay, Bertrand; Minvielle, Stéphane; Magrangeas, Florence; Guziolowski, Carito

2018-03-21

The integration of gene expression profiles (GEPs) and large-scale biological networks derived from pathways databases is a subject which is being widely explored. Existing methods are based on network distance measures among significantly measured species. Only a small number of them include the directionality and underlying logic existing in biological networks. In this study we approach the GEP-networks integration problem by considering the network logic, however our approach does not require a prior species selection according to their gene expression level. We start by modeling the biological network representing its underlying logic using Logic Programming. This model points to reachable network discrete states that maximize a notion of harmony between the molecular species active or inactive possible states and the directionality of the pathways reactions according to their activator or inhibitor control role. Only then, we confront these network states with the GEP. From this confrontation independent graph components are derived, each of them related to a fixed and optimal assignment of active or inactive states. These components allow us to decompose a large-scale network into subgraphs and their molecular species state assignments have different degrees of similarity when compared to the same GEP. We apply our method to study the set of possible states derived from a subgraph from the NCI-PID Pathway Interaction Database. This graph links Multiple Myeloma (MM) genes to known receptors for this blood cancer. We discover that the NCI-PID MM graph had 15 independent components, and when confronted to 611 MM GEPs, we find 1 component as being more specific to represent the difference between cancer and healthy profiles.

A statistically derived index for classifying East Coast fever reactions in cattle challenged with Theileria parva under experimental conditions.

PubMed

Rowlands, G J; Musoke, A J; Morzaria, S P; Nagda, S M; Ballingall, K T; McKeever, D J

2000-04-01

A statistically derived disease reaction index based on parasitological, clinical and haematological measurements observed in 309 5 to 8-month-old Boran cattle following laboratory challenge with Theileria parva is described. Principal component analysis was applied to 13 measures including first appearance of schizonts, first appearance of piroplasms and first occurrence of pyrexia, together with the duration and severity of these symptoms, and white blood cell count. The first principal component, which was based on approximately equal contributions of the 13 variables, provided the definition for the disease reaction index, defined on a scale of 0-10. As well as providing a more objective measure of the severity of the reaction, the continuous nature of the index score enables more powerful statistical analysis of the data compared with that which has been previously possible through clinically derived categories of non-, mild, moderate and severe reactions.

Affective Evaluations of and Reactions to Exterior and Interior Vehicle Auditory Quality

NASA Astrophysics Data System (ADS)

Västfjäll, D.; Gulbol, M.-A.; Kleiner, M.; Gärling, T.

2002-08-01

Affective reactions to and evaluations of auditory stimuli are fundamental components of human perception. In three experiments, participants rated their affective reactions (how pleasant I feel) and preferences for these affective reactions (how much I like the way I feel) as well as affective evaluations (how pleasant the sound is) to interior and exterior binaurally recorded vehicle sounds varying in physical properties. Consistent with previous research, it was found that the orthogonal affect dimensions of valence (unpleasant-pleasant) and arousal or activation (deactivation-activation) discriminated between affective reactions induced by the different qualities of the sounds. Moreover, preference for affective reactions was related to both valence and activation. Affective evaluations (powerful-powerless/passive-active and unpleasant-pleasant) correlated significantly with affective reactions to the same sounds in both within-subjects and between-subjects designs. Standard sound quality metrics derived from the sounds correlated, however, poorly with the affective ratings of interior sounds and only moderately with affective ratings of exterior sounds. Taken together, the results suggest that affect is an important component in product auditory quality optimization.

Registration of immunoglobuline AB/AG reaction with planar polarization interferometer

NASA Astrophysics Data System (ADS)

Nabok, Alexei V.; Starodub, Nickolaj F.; Ray, Asim K.; Hassan, Aseel K.

2000-12-01

Immobilization of human immunoglobuline (IgG) (AG) and goat on human IGG antibodies (AB) as well as AB/AG specific reaction were studied with planar polarization interferometry (PPI). In this novel method, polarized laser beam was coupled into the planar waveguide made on silicon wafer and consisted of 20nm Si3N4 layer sandwiched between two 1.5 micrometers SiO2 layers with the sensing window etched in the top SIO2 layer. One of the immune components was deposited by means of polyelectrolyte self- assembly on top of the Si3N3 layer within the sensing window, P-component of the polarized light is sensitive to adsorption, while s-component serves as a reference. Thus the outcoming light intensity depends on the phase shift between s- and p-components. Different sequences of immobilization of the immune components were studied with both surface plasmon resonance (SPR) and PPI methods. It was shown that predeposition of a monolayer of protein A, which is believed to affect the orientation of the immune components, causes an additional increase in the sensitivity. PPI method allowed us to improve substantially the sensitivity towards AB/AG reaction as compared to traditional SPR method. Particularly, of specific binding of 3ng/ml AG was registered.

Fundamental Reaction Pathway for Peptide Metabolism by Proteasome: Insights from First-principles Quantum Mechanical/Molecular Mechanical Free Energy Calculations

PubMed Central

Wei, Donghui; Fang, Lei; Tang, Mingsheng; Zhan, Chang-Guo

2013-01-01

Proteasome is the major component of the crucial nonlysosomal protein degradation pathway in the cells, but the detailed reaction pathway is unclear. In this study, first-principles quantum mechanical/molecular mechanical free energy calculations have been performed to explore, for the first time, possible reaction pathways for proteasomal proteolysis/hydrolysis of a representative peptide, succinyl-leucyl-leucyl-valyl-tyrosyl-7-amino-4-methylcoumarin (Suc-LLVY-AMC). The computational results reveal that the most favorable reaction pathway consists of six steps. The first is a water-assisted proton transfer within proteasome, activating Thr1-Oγ. The second is a nucleophilic attack on the carbonyl carbon of a Tyr residue of substrate by the negatively charged Thr1-Oγ, followed by the dissociation of the amine AMC (third step). The fourth step is a nucleophilic attack on the carbonyl carbon of the Tyr residue of substrate by a water molecule, accompanied by a proton transfer from the water molecule to Thr1-Nz. Then, Suc-LLVY is dissociated (fifth step), and Thr1 is regenerated via a direct proton transfer from Thr1-Nz to Thr1-Oγ. According to the calculated energetic results, the overall reaction energy barrier of the proteasomal hydrolysis is associated with the transition state (TS3b) for the third step involving a water-assisted proton transfer. The determined most favorable reaction pathway and the rate-determining step have provided a reasonable interpretation of the reported experimental observations concerning the substituent and isotopic effects on the kinetics. The calculated overall free energy barrier of 18.2 kcal/mol is close to the experimentally-derived activation free energy of ~18.3–19.4 kcal/mol, suggesting that the computational results are reasonable. PMID:24111489

Growth of multilayered polycrystalline reaction rims in the MgO-SiO2 system, part I: experiments

NASA Astrophysics Data System (ADS)

Gardés, E.; Wunder, B.; Wirth, R.; Heinrich, W.

2011-01-01

Growth of transport-controlled reaction layers between single crystals of periclase and quartz, and forsterite and quartz was investigated experimentally at 1.5 GPa, 1100°C to 1400°C, 5 min to 72 h under dry and melt-free conditions using a piston-cylinder apparatus. Starting assemblies consisting of Per | Qtz | Fo sandwiches produced polycrystalline double layers of forsterite and enstatite between periclase and quartz, and enstatite single layers between forsterite and quartz. The position of inert Pt-markers initially deposited at the interface of the reactants and inspection of mass balance confirmed that both layer-producing reactions are controlled by MgO diffusion, while SiO2 is relatively immobile. BSE and TEM imaging revealed thicknesses from 0.6 μm to 14 μm for double layers and from 0 to 6.8 μm for single layers. Both single and double layers displayed non-parabolic growth together with pronounced grain coarsening. Textural evolution and growth rates for each reaction are directly comparable. Forsterite-enstatite double layers are always wider than enstatite single layers, and the growth of enstatite in the double layer is slower than that in the single layer. In double layers, the enstatite/forsterite layer thickness ratio significantly increases with temperature, reflecting different MgO mobilities as temperature varies. Thus, thickness ratios in multilayered reaction zones may contain a record of temperature, but also that of any physico-chemical parameter that modifies the mobilities of the chemical components between the various layers. This potential is largely unexplored in geologically relevant systems, which calls for further experimental studies of multilayered reaction zones.

Aqueous-phase story of isoprene - A mini-review and reaction with HONO

NASA Astrophysics Data System (ADS)

Rudziński, Krzysztof J.; Szmigielski, Rafał; Kuznietsova, Inna; Wach, Paulina; Staszek, Dorota

2016-04-01

Isoprene is a major biogenic hydrocarbon emitted to the atmosphere and a well-recognized player in atmospheric chemistry, formation of secondary organic aerosol and air quality. Most of the scientific work on isoprene has focused on the gas-phase and smog chamber processing while direct aqueous chemistry has escaped the major attention because physical solubility of isoprene in water is low. Therefore, this work recollects the results of genuine research carried on atmospherically relevant aqueous-phase transformations of isoprene. It clearly shows that isoprene dissolves in water and reacts in aqueous solutions with common atmospheric oxidants such as hydrogen peroxide, ozone, hydroxyl radicals, sulfate radicals and sulfite radicals. The reactions take place in the bulk of solutions or on the gas-liquid interfaces and often are acid-catalyzed and/or enhanced by light. The review is appended by an experimental study of the aqueous-phase reaction of isoprene with nitrous acid (HONO). The decay of isoprene and formation of new products are demonstrated. The tentative chemical mechanism of the reaction is suggested, which starts with slow decomposition of HONO to NO2 and NO. The aqueous chemistry of isoprene explains the formation of a few tropospheric components identified by scientists yet considered of unknown origin. The reaction of isoprene with sulfate radicals explains formation of the MW 182 organosulfate found in ambient aerosol and rainwater while the reaction of isoprene with HONO explains formation of the MW 129 and MW 229 nitroorganic compounds identified in rainwater. Thus, aqueous transformations of isoprene should not be neglected without evidence but rather considered and evaluated in modeling of atmospheric chemical processes even if alternative and apparently dominant heterogeneous pathways of isoprene transformation, dry or wet, are demonstrated.

Foliation development and reaction softening by dissolution and precipitation in the transformation of granodiorite to orthogneiss, Glastonbury Complex, Connecticut, U.S.A

USGS Publications Warehouse

Wintsch, R.P.; Aleinikoff, J.N.; Yi, K.

2005-01-01

Textures, microstructures, and patterns of chemical zoning in minerals in a granodioritic orthogneiss in the Glastonbury Complex, Connecticut, lead to the interpretation that foliation development was facilitated by retrograde hydration reactions in the presence of an aqueous fluid. Incomplete replacement of the metastable magmatic minerals K-feldspar + hastingsite + magnetite produced foliation-defining biotite + epidote + quartz. These reaction products did not replace K-feldspar - hastingsite interfaces; rather, either biotite or epidote replaced the amphibole, and plagioclase replaced K-feldspar. Biotite and epidote precipitated syntectonically in discrete layers that define the foliation in the orthogneiss, whereas quartz precipitated primarily in ribbons, further enhancing the fabric. Metastable REE-rich igneous titanite also dissolved, and was incompletely replaced by REE-poor, Al-bearing metamorphic titanite. The similar concentrations of the REE in epidote and titanite show that the REE released by titanite dissolution were precipitated locally as the allanite component in adjacent grains of epidote. The entire process was syntectonic, with most grains showing multiple overgrowths in the direction of extension as defined by stretched xenoliths. Sufficient U was present in the titanite overgrowths to allow SHRIMP dating of cores, mantles, and rims. These results suggest at least three retrograde Alleghanian events of growth in a span of ???30 m.y. Thus the dissolution - transportation - precipitation process not only describes the reaction mechanism but also leads to the redistribution of reaction products into nearly monomineralic layers, thus contributing to metamorphic differentiation and to the development of the foliation. The resulting orthogneiss was much weaker that the granodiorite protolith, owing to this reaction and textural softening.

Advanced deposition model for thermal activated chemical vapor deposition

NASA Astrophysics Data System (ADS)

Cai, Dang

Thermal Activated Chemical Vapor Deposition (TACVD) is defined as the formation of a stable solid product on a heated substrate surface from chemical reactions and/or dissociation of gaseous reactants in an activated environment. It has become an essential process for producing solid film, bulk material, coating, fibers, powders and monolithic components. Global market of CVD products has reached multi billions dollars for each year. In the recent years CVD process has been extensively used to manufacture semiconductors and other electronic components such as polysilicon, AlN and GaN. Extensive research effort has been directed to improve deposition quality and throughput. To obtain fast and high quality deposition, operational conditions such as temperature, pressure, fluid velocity and species concentration and geometry conditions such as source-substrate distance need to be well controlled in a CVD system. This thesis will focus on design of CVD processes through understanding the transport and reaction phenomena in the growth reactor. Since the in situ monitor is almost impossible for CVD reactor, many industrial resources have been expended to determine the optimum design by semi-empirical methods and trial-and-error procedures. This approach has allowed the achievement of improvements in the deposition sequence, but begins to show its limitations, as this method cannot always fulfill the more and more stringent specifications of the industry. To resolve this problem, numerical simulation is widely used in studying the growth techniques. The difficulty of numerical simulation of TACVD crystal growth process lies in the simulation of gas phase and surface reactions, especially the latter one, due to the fact that very limited kinetic information is available in the open literature. In this thesis, an advanced deposition model was developed to study the multi-component fluid flow, homogeneous gas phase reactions inside the reactor chamber, heterogeneous surface reactions on the substrate surface, conductive, convective, inductive and radiative heat transfer, species transport and thereto-elastic stress distributions. Gas phase and surface reactions are studied thermodynamically and kinetically. Based on experimental results, detailed reaction mechanisms are proposed and the deposition rates are predicted. The deposition model proposed could be used for other experiments with similar operating conditions. Four different growth systems are presented in this thesis to discuss comprehensive transport phenomena in crystal growth from vapor. The first is the polysilicon bulk growth by modified Siemens technique in which a silicon tube is used as the starting material. The research effort has been focused on system design, geometric and operating parameters optimization, and heterogeneous and homogeneous silane pyrolysis analysis. The second is the GaN thin film growth by iodine vapor phase epitaxy technique. Heat and mass transport is studied analytically and numerically. Gas phase and surface reactions are analyzed thermodynamically and kinetically. Quasi-equilibrium and kinetic deposition models are developed to predict the growth rate. The third one is the AlN thin film growth by halide vapor phase epitaxy technique. The effects of gas phase and surface reactions on the crystal growth rate and deposition uniformity are studied. The last one is the AlN sublimation growth system. The research effort has been focused on the effect of thermal environment evolution on the crystal growth process. The thermoelastic stress formed in the as-grown AlN crystal is also calculated.

GREENER CHEMICAL SYNTHESES VIA MECHANOCHEMICAL MIXING OR USING MICROWAVE IRRADIATION IN ECO-FRIENDLY MEDIA

EPA Science Inventory

A simple approach to rapid organic synthesis or transformation using ‘greener’ reaction conditions, especially in the context of multi-component condensation reactions that are amenable to building of libraries of compounds, is very desirable. A variety of eco-friendly reactions ...

On decomposing stimulus and response waveforms in event-related potentials recordings.

PubMed

Yin, Gang; Zhang, Jun

2011-06-01

Event-related potentials (ERPs) reflect the brain activities related to specific behavioral events, and are obtained by averaging across many trial repetitions with individual trials aligned to the onset of a specific event, e.g., the onset of stimulus (s-aligned) or the onset of the behavioral response (r-aligned). However, the s-aligned and r-aligned ERP waveforms do not purely reflect, respectively, underlying stimulus (S-) or response (R-) component waveform, due to their cross-contaminations in the recorded ERP waveforms. Zhang [J. Neurosci. Methods, 80, pp. 49-63, 1998] proposed an algorithm to recover the pure S-component waveform and the pure R-component waveform from the s-aligned and r-aligned ERP average waveforms-however, due to the nature of this inverse problem, a direct solution is sensitive to noise that disproportionally affects low-frequency components, hindering the practical implementation of this algorithm. Here, we apply the Wiener deconvolution technique to deal with noise in input data, and investigate a Tikhonov regularization approach to obtain a stable solution that is robust against variances in the sampling of reaction-time distribution (when number of trials is low). Our method is demonstrated using data from a Go/NoGo experiment about image classification and recognition.

``Seeing'' electroencephalogram through the skull: imaging prefrontal cortex with fast optical signal

NASA Astrophysics Data System (ADS)

Medvedev, Andrei V.; Kainerstorfer, Jana M.; Borisov, Sergey V.; Gandjbakhche, Amir H.; Vanmeter, John

2010-11-01

Near-infrared spectroscopy is a novel imaging technique potentially sensitive to both brain hemodynamics (slow signal) and neuronal activity (fast optical signal, FOS). The big challenge of measuring FOS noninvasively lies in the presumably low signal-to-noise ratio. Thus, detectability of the FOS has been controversially discussed. We present reliable detection of FOS from 11 individuals concurrently with electroencephalogram (EEG) during a Go-NoGo task. Probes were placed bilaterally over prefrontal cortex. Independent component analysis (ICA) was used for artifact removal. Correlation coefficient in the best correlated FOS-EEG ICA pairs was highly significant (p < 10-8), and event-related optical signal (EROS) was found in all subjects. Several EROS components were similar to the event-related potential (ERP) components. The most robust ``optical N200'' at t = 225 ms coincided with the N200 ERP; both signals showed significant difference between targets and nontargets, and their timing correlated with subject's reaction time. Correlation between FOS and EEG even in single trials provides further evidence that at least some FOS components ``reflect'' electrical brain processes directly. The data provide evidence for the early involvement of prefrontal cortex in rapid object recognition. EROS is highly localized and can provide cost-effective imaging tools for cortical mapping of cognitive processes.

“Seeing” electroencephalogram through the skull: imaging prefrontal cortex with fast optical signal

PubMed Central

Medvedev, Andrei V.; Kainerstorfer, Jana M.; Borisov, Sergey V.; Gandjbakhche, Amir H.; VanMeter, John

2010-01-01

Near-infrared spectroscopy is a novel imaging technique potentially sensitive to both brain hemodynamics (slow signal) and neuronal activity (fast optical signal, FOS). The big challenge of measuring FOS noninvasively lies in the presumably low signal-to-noise ratio. Thus, detectability of the FOS has been controversially discussed. We present reliable detection of FOS from 11 individuals concurrently with electroencephalogram (EEG) during a Go-NoGo task. Probes were placed bilaterally over prefrontal cortex. Independent component analysis (ICA) was used for artifact removal. Correlation coefficient in the best correlated FOS–EEG ICA pairs was highly significant (p < 10−8), and event-related optical signal (EROS) was found in all subjects. Several EROS components were similar to the event-related potential (ERP) components. The most robust “optical N200” at t = 225 ms coincided with the N200 ERP; both signals showed significant difference between targets and nontargets, and their timing correlated with subject’s reaction time. Correlation between FOS and EEG even in single trials provides further evidence that at least some FOS components “reflect” electrical brain processes directly. The data provide evidence for the early involvement of prefrontal cortex in rapid object recognition. EROS is highly localized and can provide cost-effective imaging tools for cortical mapping of cognitive processes. PMID:21198150

Anomalous yield reduction in direct-drive deuterium/tritium implosions due to 3He addition

NASA Astrophysics Data System (ADS)

Herrmann, H. W.; Langenbrunner, J. R.; Mack, J. M.; Cooley, J. H.; Wilson, D. C.; Evans, S. C.; Sedillo, T. J.; Kyrala, G. A.; Caldwell, S. E.; Young, C. S.; Nobile, A.; Wermer, J.; Paglieri, S.; McEvoy, A. M.; Kim, Y.; Batha, S. H.; Horsfield, C. J.; Drew, D.; Garbett, W.; Rubery, M.; Glebov, V. Yu.; Roberts, S.; Frenje, J. A.

2009-05-01

Glass capsules were imploded in direct drive on the OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)] to look for anomalous degradation in deuterium/tritium (DT) yield and changes in reaction history with H3e addition. Such anomalies have previously been reported for D/H3e plasmas but had not yet been investigated for DT/H3e. Anomalies such as these provide fertile ground for furthering our physics understanding of inertial confinement fusion implosions and capsule performance. Anomalous degradation in the compression component of yield was observed, consistent with the "factor of 2" degradation previously reported by Massachusetts Institute of Technology (MIT) at a 50% H3e atom fraction in D2 using plastic capsules [Rygg, Phys. Plasmas 13, 052702 (2006)]. However, clean calculations (i.e., no fuel-shell mixing) predict the shock component of yield quite well, contrary to the result reported by MIT but consistent with Los Alamos National Laboratory results in D2/H3e [Wilson et al., J. Phys.: Conf. Ser. 112, 022015 (2008)]. X-ray imaging suggests less-than-predicted compression of capsules containing H3e. Leading candidate explanations are poorly understood equation of state for gas mixtures and unanticipated particle pressure variation with increasing H3e addition.

Recommendations for safe vaccination in children at the risk of taking allergic reactions to vaccine components

PubMed

2018-04-01

Vaccines are one of the most important advances in medicine as a public health tool for the control of immunopreventable diseases. Occasionally, adverse reactions may occur. If a child has a reaction to a vaccine, it is likely to disrupt his immunization schedule with risks to himself and the community. This establishes the importance of correctly diagnosing a possible allergy and defining appropriate behavior. Allergic reactions to vaccines may be due to the immunogenic component, to the residual proteins in the manufacturing process and to antimicrobial agents, stabilizers, preservatives and any other element used in the manufacturing process. Vaccination should be a priority in the entire child population, so this document describes particular situations of allergic children to minimize the risk of immunizations and achieve safe vaccination.

Alpha-capture reaction rates for 22Ne(alpha,n) via sub-Coulomb alpha-transfer

NASA Astrophysics Data System (ADS)

Jayatissa, Heshani; Rogachev, Grigory; Koshchiy, Yevgen; Goldberg, Vladilen; Bedoor, Shadi; Hooker, Joshua; Hunt, Curtis; Magana, Cordero; Roeder, Brian; Saastamoinen, Antti; Spiridon, Alexandria; Upadhyayula, Sriteja

2016-09-01

Direct measurements of α-capture reactions at energies relevant to astrophysics is extremely difficult to carry out due to the very small reaction cross section. The large uncertainties introduced when extrapolating direct measurements at high energies down to the Gamow energies can be overcome by measuring the Asymptotic Normalization Coefficients (ANC) of the relevant states using (6Li,d) α-transfer reactions at sub-Coulomb energies to reduce the model dependence. The study of the 22Ne(6Li,d) reaction was carried out at the Cyclotron Institute at Texas A&M University. The α-ANC measurements for the near α-threshold resonances of 26Mg will provide constraints for the reaction rate of the 22Ne(α,n) reaction.

A comparison of ground reaction force components according to the foothold heights in 16-t truck during downward step.

PubMed

Hyun, Seung-Hyun; Ryew, Che-Cheong

2017-12-01

The aim of this study is to compare and analyze the components of ground reaction force (GRF) relative to the foothold heights during downward step of 16-t truck. Adult males (n= 10) jumped downward from each 1st, 2nd, 3rd foothold step and driver's seat orderly using hand rail. Sampling rate of force components of 3 axis (medial-lateral [ML] GRF, anterior-posterior [AP] GRF, peak vertical force [PVF]), variables (COPx, COPy, COP area) of center of pressure (COP), loading rate, and stability index (ML, AP, vertical, and dynamic postural stability index [DPSI]) processed from GRF system was cut off at 1,000 Hz. and variables was processed with repeated one-way analysis of variance. AP GRF, PVF and loading rate showed higher value in case of not used hand rail than that used hand rail in all 1st, 2nd, and 3rd of foothold step. DPSI showed more lowered stability in order of 2nd, 3rd step than 1st foothold step used with hand rail, of which showed lowest stability from driver's seat. COPx, COPy, and COP area showed higher value in case of 2nd and 3rd than that of 1st of foothold step, and showed lowest stability from driver's seat. It is more desirable for cargo truck driver to utilize an available hand rail in order of 3rd, 2nd, and 1st of foothold step than downward stepping directly, thus by which may results in decrease of falling injuries and minimization of impulsive force transferring to muscular-skeletal system.

Asymmetric synthesis of isoindolones by chiral cyclopentadienyl-rhodium(III)-catalyzed C-H functionalizations.

PubMed

Ye, Baihua; Cramer, Nicolai

2014-07-21

Directed Cp*Rh(III)-catalyzed carbon-hydrogen (C-H) bond functionalizations have evolved as a powerful strategy for the construction of heterocycles. Despite their high value, the development of related asymmetric reactions is largely lagging behind due to a limited availability of robust and tunable chiral cyclopentadienyl ligands. Rhodium complexes comprising a chiral Cp ligand with an atropchiral biaryl backbone enables an asymmetric synthesis of isoindolones from arylhydroxamates and weakly alkyl donor/acceptor diazo derivatives as one-carbon component under mild conditions. The complex guides the substrates with a high double facial selectivity yielding the chiral isoindolones in good yields and excellent enantioselectivities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polarization-transfer measurement to a large-virtuality bound proton in the deuteron

NASA Astrophysics Data System (ADS)

Yaron, I.; Izraeli, D.; Achenbach, P.; Arenhövel, H.; Beričič, J.; Böhm, R.; Bosnar, D.; Cohen, E. O.; Debenjak, L.; Distler, M. O.; Esser, A.; Friščić, I.; Gilman, R.; Korover, I.; Lichtenstadt, J.; Merkel, H.; Middleton, D. G.; Mihovilovič, M.; Müller, U.; Piasetzky, E.; Pochodzalla, J.; Ron, G.; Schlimme, B. S.; Schoth, M.; Schulz, F.; Sfienti, C.; Širca, S.; Strauch, S.; Thiel, M.; Tyukin, A.; Weber, A.; A1 Collaboration

2017-06-01

We report the measurement of the ratio of polarization-transfer components, Px /Pz, in the 2H (e → ,e‧ p →) n reaction at low and high missing momenta, in search of differences between free and bound protons. The observed deviation of Px /Pz from that of a free proton, which is similar to that observed in 4He, indicates that the effect in nuclei is a function of the virtuality of the knock-out proton and the missing momentum direction, but not the average nuclear density. There is a general agreement between the data and calculations, which assume free proton form factors, however, the measurements are consistently about 10% higher.

Process for fixed bed coal gasification

DOEpatents

Sadowski, Richard S.

1992-01-01

The combustion of gas produced from the combination of coal pyrolysis and gasification involves combining a combustible gas coal and an oxidant in a pyrolysis chamber and heating the components to a temperature of at least 1600.degree. F. The products of coal pyrolysis are dispersed from the pyrolyzer directly into the high temperature gasification region of a pressure vessel. Steam and air needed for gasification are introduced in the pressure vessel and the materials exiting the pyrolyzer flow down through the pressure vessel by gravity with sufficient residence time to allow any carbon to form carbon monoxide. Gas produced from these reactions are then released from the pressure vessel and ash is disposed of.

Students' Physical and Psychological Reactions to Forensic Dissection: Are There Risk Factors?

ERIC Educational Resources Information Center

Sergentanis, Theodoros N.; Papadodima, Stavroula A.; Evaggelakos, Christos I.; Mytilinaios, Dimitrios G.; Goutas, Nikolaos D.; Spiliopoulou, Chara A.

2010-01-01

The reactions of students to forensic dissection encompass psychologico-emotional and physical components. This exploratory study aimed to determine risk factors for students' adverse physical and psychological reactions to forensic dissection. All sixth-year medical students (n = 304) attending the compulsory practical course in forensic medicine…

A Gas-Kinetic Scheme for Multimaterial Flows and Its Application in Chemical Reaction

NASA Technical Reports Server (NTRS)

Lian, Yongsheng; Xu, Kun

1999-01-01

This paper concerns the extension of the multicomponent gas-kinetic BGK-type scheme to multidimensional chemical reactive flow calculations. In the kinetic model, each component satisfies its individual gas-kinetic BGK equation and the equilibrium states of both components are coupled in space and time due to the momentum and energy exchange in the course of particle collisions. At the same time, according to the chemical reaction rule one component can be changed into another component with the release of energy, where the reactant and product could have different gamma. Many numerical test cases are included in this paper, which show the robustness and accuracy of kinetic approach in the description of multicomponent reactive flows.

Study on the pulse reaction technique. VI. Kinetics of the reaction of NO with NH/sub 3/ on a V/sub 2/O/sub 5/ catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyamoto, A.; Yamazaki, Y.; Hattori, T.

1982-01-01

In order to examine the applicability of the rectangular pulse technique to the determination of the kinetics of a two-components' reaction on a catalyst in the specified surface state, the kinetics of the reaction of NO with NH/sub 3/ on the V/sub 2/O/sub 5/ catalyst, that is, NO + NH/sub 3/ + VVertical BarO ..-->.. N/sub 2/ + H/sub 2/O + V-OH, has been investigated using the rectangular pulse apparatus. Chromatograms of the individual components have shown that NH/sub 3/ is strongly adsorbed on the catalyst while NO or N/sub 2/ is not or only very weakly adsorbed. The adsorptionmore » of NH/sub 3/ has been approximately described by the Langmuir adsorption isotherm. The yield of N/sub 2/ produced by the reaction has changed significantly with the pusle width. This indicates a separation of NO and NH/sub 3/ in the catalyst bed during the pulse experiments. By analyzing the experimental data with the theory of the pulse technique, the kinetics of the above-mentioned two-components' reaction has successfully been determined and it has agreed with the kinetics of the reaction of NO with NH/sub 3/ under excess oxygen conditions determined by using the continuous flow technique. On the basis of these results, the rectangular pulse technique coupled with the theoretical analsysis of the experimental data has been concluded to be a method effective for the determination of the kinetics of a multicomponents' reaction on a catalyst in the specified surface state.« less

Rhodium(III)-catalyzed three-component reaction of imines, alkynes, and aldehydes through C-H activation.

PubMed

Huang, Ji-Rong; Song, Qiang; Zhu, Yu-Qin; Qin, Liu; Qian, Zhi-Yong; Dong, Lin

2014-12-15

An efficient rhodium(III)-catalyzed tandem three-component reaction of imines, alkynes and aldehydes through CH activation has been developed. High stereo- and regioselectivity, as well as good yields were obtained in most cases. The simple and atom-economical approach offers a broad scope of substrates, providing polycyclic skeletons with potential biological properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unexpected formation of (E)-4-alkene 1,3-diketones from the three-component reaction of lithium selenolates with 1-(1-alkynyl)cyclopropyl ketones and aldehydes.

PubMed

Xu, Jianfeng; Wu, Luling; Huang, Xian

2011-07-15

A novel three-component stereoselective synthesis of (E)-4-alkene 1,3-diketones from lithium selenolates, 1-(1-alkynyl)cyclopropyl ketones, and aldehydes is reported. This reaction afforded the products in moderate to good yields with the formation of a new C-Se single bond, a new C-C double bond, and a new C-O double bond.

Direct catalytic asymmetric aldol-Tishchenko reaction.

PubMed

Gnanadesikan, Vijay; Horiuchi, Yoshihiro; Ohshima, Takashi; Shibasaki, Masakatsu

2004-06-30

A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.

Advancing the Theory of Nuclear Reactions with Rare Isotopes: From the Laboratory to the Cosmos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elster, Charlotte

2015-06-01

The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. Ohio University concentrates its efforts on the first part of the mission. Since direct measurements are often not feasible, indirect methods, e.g. (d,p) reactions, should be used. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques. Faddeev equations in momentum space have a long tradition of utilizing separable interactions in ordermore » to arrive at sets of coupled integral equations in one variable. While there exist several separable representations for the nucleon-nucleon interaction, the optical potential between a neutron (proton) and a nucleus is not readily available in separable form. For this reason we first embarked in introducing a separable representation for complex phenomenological optical potentials of Woods-Saxon type.« less

Apheresis technology correlates with bacterial contamination of platelets and reported septic transfusion reactions.

PubMed

Eder, Anne F; Dy, Beth A; DeMerse, Barbara; Wagner, Stephen J; Stramer, Susan L; O'Neill, E Mary; Herron, Ross M

2017-12-01

Apheresis technology to collect platelet (PLT) components differs among devices. We evaluated the relationship of the plateletpheresis device with bacterial contamination and reported septic transfusion reactions. Plateletpheresis was performed using Amicus (Fenwal, a Fresenius Kabi Company) or Trima (Trima Accel, TerumoBCT) from 2010 to 2014. All donations used inlet-line sample diversion and were tested by quality control (QC; Day 1) aerobic culture. Rates of bacterial contamination and septic reactions to PLTs were calculated for both devices. During the 5-year study period, plateletpheresis collections using Amicus and Trima devices totaled 1,486,888 and 671,955 donations, respectively. The rate of confirmed-positive bacterial cultures of apheresis PLT donations was significantly higher with Amicus than with Trima (252 vs. 112 per 10 6 donations [odds ratio {OR}, 2.3; 95% confidence interval {CI}, 1.8-2.9]). Septic transfusion reactions were caused by 30 apheresis PLT units from 25 contaminated Amicus procedures and three apheresis PLT units from three contaminated Trima procedures. The overall rate of septic reactions was significantly higher with apheresis PLT components collected with Amicus than with Trima (16.8 vs. 4.5 per 10 6 donations [OR, 3.8; 95% CI, 1.1-12.5]). All apheresis PLT components implicated in septic transfusion reactions had negative QC culture results incubated through Day 5 (i.e., false negatives). Apheresis technology affects bacterial contamination of plateletpheresis collections. The device-specific, higher rate of confirmed-positive bacterial culture results also correlated with a significantly higher rate of reported septic transfusion reactions to apheresis PLTs. © 2017 AABB.

Effects of uncertainty, transmission type, driver age and gender on brake reaction and movement time.

PubMed

Warshawsky-Livne, Lora; Shinar, David

2002-01-01

Braking time (BT) is a critical component in safe driving, and various approaches have been applied to minimize it. This study analyzed the components of BT in order to assess the effects of age, gender, vehicle transmission type, and event uncertainty, on its two primary components, perception-reaction time and brake-movement time. Perception-reaction time and brake-movement time were measured at the onset of lights for 72 subjects in a simulator. The six experimental conditions were three levels of uncertainty conditions (none, some, and some + false alarms) and two types of transmission (manual and automatic). The 72 subjects, half male and half female, were further divided into three age groups (mean of 23, 30, and 62 years). Each subject had 10 trials in each of the three levels of uncertainty conditions. Transmission type did not significantly affect either perception-reaction time or brake-movement time. Perception-reaction time increased significantly from 0.32 to 0.42 s (P < .05) as uncertainty increased but brake-movement time did not change. Perception-reaction time increased (from 0.35 to 0.43 s) with age but brake-movement time did not change with age. Gender did not affect perception-reaction time but did affect brake-movement time (males 0.19 s vs. females 0.16 s). At 90 km/h, a car travels 0.25 m in 0.01 s. Consequently, even such small effects multiplied by millions of vehicle-kilometers can contribute to significant savings in lives and damages.

Optical properties of in-vitro biomineralised silica

PubMed Central

Polini, Alessandro; Pagliara, Stefano; Camposeo, Andrea; Cingolani, Roberto; Wang, Xiaohong; Schröder, Heinz C.; Müller, Werner E. G.; Pisignano, Dario

2012-01-01

Silicon is the second most common element on the Earth's crust and its oxide (SiO2) the most abundant mineral. Silica and silicates are widely used in medicine and industry as well as in micro- and nano-optics and electronics. However, the fabrication of glass fibres and components requires high temperature and non-physiological conditions, in contrast to biosilica structures in animals and plants. Here, we show for the first time the use of recombinant silicatein-α, the most abundant subunit of sponge proteins catalyzing biosilicification reactions, to direct the formation of optical waveguides in-vitro through soft microlithography. The artificial biosilica fibres mimic the natural sponge spicules, exhibiting refractive index values suitable for confinement of light within waveguides, with optical losses in the range of 5–10 cm−1, suitable for application in lab-on-chips systems. This method extends biosilicification to the controlled fabrication of optical components by physiological processing conditions, hardly addressed by conventional technologies. PMID:22934130

Pyridostigmine bromide and the long-term subjective health status of a sample of over 700 male Reserve Component Gulf War era veterans.

PubMed

Schumm, Walter R; Reppert, Earl J; Jurich, Anthony P; Bollman, Stephan R; Webb, Farrell J; Castelo, Carlos S; Stever, James C; Kaufman, Mark; Deng, Liang-Yu; Krehbiel, Michelle; Owens, Barbara L; Hall, Carolyn A; Brown, Beverlyn F Cay; Lash, Jeanne F; Fink, Carol J; Crow, Janet R; Bonjour, Gabriele N

2002-06-01

Data from a 1996-1997 survey of approximately 700 Reserve Component male veterans indicate that the consumption of pyridostigmine bromide pills, used as a pretreatment for potential exposure to the nerve agent Soman, was a significant predictor of declines in reported subjective health status after the war, even after controlling for a number of other possible factors. Reported reactions to vaccines and other medications also predicted declines in subjective health. While higher military rank generally predicted better health during and after the war, educational attainment, minority status, number of days in theater, and age generally did not predict changes in subjective health. Although servicemembers were directed to take three pills a day, veterans reported a range of compliance--less than a fourth (24%) followed the medical instructions compared to 61% who took fewer than three pills daily and 6% who took six or more pills a day. Implications for use of pyridostigmine bromide are discussed.

Individual differences in the recognition of facial expressions: an event-related potentials study.

PubMed

Tamamiya, Yoshiyuki; Hiraki, Kazuo

2013-01-01

Previous studies have shown that early posterior components of event-related potentials (ERPs) are modulated by facial expressions. The goal of the current study was to investigate individual differences in the recognition of facial expressions by examining the relationship between ERP components and the discrimination of facial expressions. Pictures of 3 facial expressions (angry, happy, and neutral) were presented to 36 young adults during ERP recording. Participants were asked to respond with a button press as soon as they recognized the expression depicted. A multiple regression analysis, where ERP components were set as predictor variables, assessed hits and reaction times in response to the facial expressions as dependent variables. The N170 amplitudes significantly predicted for accuracy of angry and happy expressions, and the N170 latencies were predictive for accuracy of neutral expressions. The P2 amplitudes significantly predicted reaction time. The P2 latencies significantly predicted reaction times only for neutral faces. These results suggest that individual differences in the recognition of facial expressions emerge from early components in visual processing.

The Role of the Isospin 3/2 Component in Elastic Neutron-Deuteron Scattering and in the Deuteron Breakup Reaction

NASA Astrophysics Data System (ADS)

Witała, H.; Golak, J.; Skibiński, R.; Topolnicki, K.; Kamada, H.

We discuss the importance of the three-nucleon isospin T = 3/2 component in elastic neutron-deuteron scattering and in the deuteron breakup reaction. The contribution of this amplitude originates from charge-independence breaking of the nucleon-nucleon potential. We study the magnitude of that contribution to the elastic scattering and breakup observables, taking the Av18 nucleon-nucleon potential alone or combined with the Urbana IX three-nucleon force as well as the locally regularized chiral N4LO nucleon-nucleon potential alone or supplemented by the chiral N2LO three-nucleon force. We find that the isospin T = 3/2 component is important for the breakup reaction and the proper treatment of charge-independence breaking in this case requires the inclusion of the 1S 0 state with isospin T = 3/2. For neutron-deuteron elastic scattering the T = 3/2 contributions are insignificant and charge-independence breaking can be accounted for by neglecting T = 3/2 component and using the effective t-matrix generated with the so-called “2/3 ‑ 1/3″ rule.

Azide/alkyne-"click"-reactions of encapsulated reagents: toward self-healing materials.

PubMed

Gragert, Maria; Schunack, Marlen; Binder, Wolfgang H

2011-03-02

The successful encapsulation of reactive components for the azide/alkyne-"click"-reaction is reported featuring for the first time the use of a liquid polymer as reactive component. A liquid, azido-telechelic three-arm star poly(isobutylene) (M(n) = 3900 g · mol⁻¹) as well as trivalent alkynes were encapsulated into micron-sized capsules and embedded into a polymer-matrix (high-molecular weight poly(isobutylene), M(n) = 250,000 g · mol⁻¹). Using (Cu(I)Br(PPh₃)₃) as catalyst for the azide/alkyne-"click"-reaction, crosslinking of the two components at 40 °C is observed within 380 min and as fast as 10 min at 80 °C. Significant recovery of the tensile storage modulus was observed in a material containing 10 wt.-% and accordingly 5 wt.-% capsules including the reactive components within 5 d at room temperature, thus proving a new concept for materials with self-healing properties. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Purification of optical imaging ligand-Cybesin by high-speed counter-current chromatography

PubMed Central

Ma, Zhiyong; Ma, Ying; Sun, Xilin; Ye, Yunpeng; Shen, Baozhong; Chen, Xiaoyuan; Ito, Yoichiro

2010-01-01

Fluorescent Cybesin (Cypate-Bombesin Peptide Analogue Conjugate) was synthesized from Indocyanine Green (ICG) and the bombesin receptor ligand as a contrast agent for detecting pancreas tumors. However, the LC–MS analysis indicated that the target compound was only a minor component in the reaction mixture. Since preparative HPLC can hardly separate such a small amount of the target compound directly from the original crude reaction mixture without a considerable adsorptive loss onto the solid support, high-speed counter-current chromatography (HSCCC) was used for purification since the method uses no solid support and promises high sample recovery. A suitable two-phase solvent system composed of hexane/ethyl acetate/methanol/methyl t.-butyl ether/acetonitrile/water) at a volume ratio of 1:1:1:4:4:7 was selected based on the partition coefficient of Cybesin (K ≈ 0.9) determined by LC–MS. The separation was performed in two steps using the same solvent system with lower aqueous mobile phase. From 400 mg of the crude reaction mixture the first separation yielded 7.7 mg of fractions containing the target compound at 12.8% purity, and in the second run 1 mg of Cybesin was obtained at purity of 94.0% with a sample recovery rate of over 95% based on the LC–MS Analysis. PMID:20933483

Reaction Mechanism and Molecular Basis for Selenium/Sulfur Discrimination of Selenocysteine Lyase*

PubMed Central

Omi, Rie; Kurokawa, Suguru; Mihara, Hisaaki; Hayashi, Hideyuki; Goto, Masaru; Miyahara, Ikuko; Kurihara, Tatsuo; Hirotsu, Ken; Esaki, Nobuyoshi

2010-01-01

Selenocysteine lyase (SCL) catalyzes the pyridoxal 5′-phosphate-dependent removal of selenium from l-selenocysteine to yield l-alanine. The enzyme is proposed to function in the recycling of the micronutrient selenium from degraded selenoproteins containing selenocysteine residue as an essential component. The enzyme exhibits strict substrate specificity toward l-selenocysteine and no activity to its cognate l-cysteine. However, it remains unclear how the enzyme distinguishes between selenocysteine and cysteine. Here, we present mechanistic studies of selenocysteine lyase from rat. ESI-MS analysis of wild-type and C375A mutant SCL revealed that the catalytic reaction proceeds via the formation of an enzyme-bound selenopersulfide intermediate on the catalytically essential Cys-375 residue. UV-visible spectrum analysis and the crystal structure of SCL complexed with l-cysteine demonstrated that the enzyme reversibly forms a nonproductive adduct with l-cysteine. Cys-375 on the flexible loop directed l-selenocysteine, but not l-cysteine, to the correct position and orientation in the active site to initiate the catalytic reaction. These findings provide, for the first time, the basis for understanding how trace amounts of a selenium-containing substrate is distinguished from excessive amounts of its cognate sulfur-containing compound in a biological system. PMID:20164179

Anchoring and promotion effects of metal oxides on silica supported catalytic gold nanoparticles.

PubMed

Luo, Jingjie; Ersen, Ovidiu; Chu, Wei; Dintzer, Thierry; Petit, Pierre; Petit, Corinne

2016-11-15

The understanding of the interactions between the different components of supported metal doped gold catalysts is of crucial importance for selecting and designing efficient gold catalysts for reactions such as CO oxidation. To progress in this direction, a unique supported nano gold catalyst Au/SS was prepared, and three doped samples (Au/SS@M) were elaborated. The samples before and after test were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). It is found that the doping metal species prefer to be located on the surface of gold nanoparticles and that a small amount of additional reductive metal leads to more efficient reaction. During the catalytic test, the nano-structure of the metal species transforms depending on its chemical nature. This study allows one to identify and address the contribution of each metal on the CO reaction in regard to oxidative species of gold, silica and dopants. Metal doping leads to different exposure of interface sites between Au and metal oxide, which is one of the key factors for the change of the catalytic activity. The metal oxides help the activation of oxygen by two actions: mobility inside the metal bulk and transfer of water species onto of gold nanoparticles. Copyright © 2016. Published by Elsevier Inc.

Rationally-designed configuration of directly-coated Ni 3S 2/Ni electrode by RGO providing superior sodium storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Xiaosheng; Li, Xifei; Bai, Zhimin

Designing nanocomposite materials is an effective approach for enhancing the performance of sodium-ion batteries (SIBs), and understanding the synergy among components is critically important for new, better materials design. Here in this paper, a directly reduced graphene oxide (RGO) decorated anode electrode was designed and tested for SIBs, in which uniform RGO coating onto the Ni 3S 2/Ni electrode was realized using facile hydrothermal reactions. The results indicate that the RGO/Ni 3S 2/Ni electrode delivers a high reversible specific capacity of 448.6 mAh g -1, high capacity retention of 96.5% after 100 cycles, and excellent rate capability of 263.1 mAhmore » g -1 at 800 mA g -1. Compared with the Ni 3S 2/Ni electrode, the improved performance of the RGO/Ni 3S 2/Ni electrode benefits from RGO-promoted displacement reaction of Ni 3S 2 with sodium. DFT calculations reveal that the RGO layer can significantly improve the electron mobility of the RGO/Ni 3S 2 + Na structure, and the hybrid interaction between the extraneous p orbits of C and indigenous p and d orbits of Ni, as well as p orbits of S is the major reason for why RGO can improve the electrical transport properties.« less

Metabolic characterization of cultured mammalian cells by mass balance analysis, tracer labeling experiments and computer-aided simulations.

PubMed

Okahashi, Nobuyuki; Kohno, Susumu; Kitajima, Shunsuke; Matsuda, Fumio; Takahashi, Chiaki; Shimizu, Hiroshi

2015-12-01

Studying metabolic directions and flow rates in cultured mammalian cells can provide key information for understanding metabolic function in the fields of cancer research, drug discovery, stem cell biology, and antibody production. In this work, metabolic engineering methodologies including medium component analysis, (13)C-labeling experiments, and computer-aided simulation analysis were applied to characterize the metabolic phenotype of soft tissue sarcoma cells derived from p53-null mice. Cells were cultured in medium containing [1-(13)C] glutamine to assess the level of reductive glutamine metabolism via the reverse reaction of isocitrate dehydrogenase (IDH). The specific uptake and production rates of glucose, organic acids, and the 20 amino acids were determined by time-course analysis of cultured media. Gas chromatography-mass spectrometry analysis of the (13)C-labeling of citrate, succinate, fumarate, malate, and aspartate confirmed an isotopically steady state of the cultured cells. After removing the effect of naturally occurring isotopes, the direction of the IDH reaction was determined by computer-aided analysis. The results validated that metabolic engineering methodologies are applicable to soft tissue sarcoma cells derived from p53-null mice, and also demonstrated that reductive glutamine metabolism is active in p53-null soft tissue sarcoma cells under normoxia. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Asymmetric synthesis of a potent, aminopiperidine-fused imidazopyridine dipeptidyl peptidase IV inhibitor.

PubMed

Xu, Feng; Corley, Edward; Zacuto, Michael; Conlon, David A; Pipik, Brenda; Humphrey, Guy; Murry, Jerry; Tschaen, David

2010-03-05

A practical asymmetric synthesis of a novel aminopiperidine-fused imidazopyridine dipeptidyl peptidase IV (DPP-4) inhibitor 1 has been developed. Application of a unique three-component cascade coupling with chiral nitro diester 7, which is easily accessed via a highly enantioselective Michael addition of dimethyl malonate to a nitrostyrene, allows for the assembly of the functionalized piperidinone skeleton in one pot. Through a base-catalyzed, dynamic crystallization-driven process, the cis-piperidionone 16a is epimerized to the desired trans isomer 16b, which is directly crystallized from the crude reaction stream in high yield and purity. Isomerization of the allylamide 16b in the presence of RhCl(3) is achieved without any epimerization of the acid/base labile stereogenic center adjacent to the nitro group on the piperidinone ring, while the undesired enamine intermediate is consumed to <0.5% by utilizing a trace amount of HCl generated from RhCl(3). The amino lactam 4, obtained through hydrogenation and hydrolysis, is isolated as its crystalline pTSA salt from the reaction solution directly, as such intramolecular transamidation has been dramatically suppressed via kinetic control. Finally, a Cu(I) catalyzed coupling-cyclization allows for the formation of the tricyclic structure of the potent DPP-4 inhibitor 1. The synthesis, which is suitable for large scale preparation, is accomplished in 23% overall yield.

The Physics and Physical Chemistry of Molecular Machines.

PubMed

Astumian, R Dean; Mukherjee, Shayantani; Warshel, Arieh

2016-06-17

The concept of a "power stroke"-a free-energy releasing conformational change-appears in almost every textbook that deals with the molecular details of muscle, the flagellar rotor, and many other biomolecular machines. Here, it is shown by using the constraints of microscopic reversibility that the power stroke model is incorrect as an explanation of how chemical energy is used by a molecular machine to do mechanical work. Instead, chemically driven molecular machines operating under thermodynamic constraints imposed by the reactant and product concentrations in the bulk function as information ratchets in which the directionality and stopping torque or stopping force are controlled entirely by the gating of the chemical reaction that provides the fuel for the machine. The gating of the chemical free energy occurs through chemical state dependent conformational changes of the molecular machine that, in turn, are capable of generating directional mechanical motions. In strong contrast to this general conclusion for molecular machines driven by catalysis of a chemical reaction, a power stroke may be (and often is) an essential component for a molecular machine driven by external modulation of pH or redox potential or by light. This difference between optical and chemical driving properties arises from the fundamental symmetry difference between the physics of optical processes, governed by the Bose-Einstein relations, and the constraints of microscopic reversibility for thermally activated processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rationally-designed configuration of directly-coated Ni 3S 2/Ni electrode by RGO providing superior sodium storage

DOE PAGES

Song, Xiaosheng; Li, Xifei; Bai, Zhimin; ...

2018-02-28

Designing nanocomposite materials is an effective approach for enhancing the performance of sodium-ion batteries (SIBs), and understanding the synergy among components is critically important for new, better materials design. Here in this paper, a directly reduced graphene oxide (RGO) decorated anode electrode was designed and tested for SIBs, in which uniform RGO coating onto the Ni 3S 2/Ni electrode was realized using facile hydrothermal reactions. The results indicate that the RGO/Ni 3S 2/Ni electrode delivers a high reversible specific capacity of 448.6 mAh g -1, high capacity retention of 96.5% after 100 cycles, and excellent rate capability of 263.1 mAhmore » g -1 at 800 mA g -1. Compared with the Ni 3S 2/Ni electrode, the improved performance of the RGO/Ni 3S 2/Ni electrode benefits from RGO-promoted displacement reaction of Ni 3S 2 with sodium. DFT calculations reveal that the RGO layer can significantly improve the electron mobility of the RGO/Ni 3S 2 + Na structure, and the hybrid interaction between the extraneous p orbits of C and indigenous p and d orbits of Ni, as well as p orbits of S is the major reason for why RGO can improve the electrical transport properties.« less

Principal component analysis on a torus: Theory and application to protein dynamics.

PubMed

Sittel, Florian; Filk, Thomas; Stock, Gerhard

2017-12-28

A dimensionality reduction method for high-dimensional circular data is developed, which is based on a principal component analysis (PCA) of data points on a torus. Adopting a geometrical view of PCA, various distance measures on a torus are introduced and the associated problem of projecting data onto the principal subspaces is discussed. The main idea is that the (periodicity-induced) projection error can be minimized by transforming the data such that the maximal gap of the sampling is shifted to the periodic boundary. In a second step, the covariance matrix and its eigendecomposition can be computed in a standard manner. Adopting molecular dynamics simulations of two well-established biomolecular systems (Aib 9 and villin headpiece), the potential of the method to analyze the dynamics of backbone dihedral angles is demonstrated. The new approach allows for a robust and well-defined construction of metastable states and provides low-dimensional reaction coordinates that accurately describe the free energy landscape. Moreover, it offers a direct interpretation of covariances and principal components in terms of the angular variables. Apart from its application to PCA, the method of maximal gap shifting is general and can be applied to any other dimensionality reduction method for circular data.

Synthesis of calcium carbonate using extract components of croaker gill as morphology and polymorph adjust control agent.

PubMed

Chen, Hao; Qing, Chengsong; Zheng, Jiaoling; Liu, Yuxi; Wu, Gang

2016-06-01

Biomimetic synthesis of calcium carbonate with various polymorphs, sizes and morphologies by using organic substrates has become an interesting topic for the last years. Calcium carbonate has been synthesized by the reaction of Na2CO3 and CaCl2 in the presence of extract components of croaker gill. The products were characterized by powder X-ray diffraction (PXRD) and Fourier transform infrared (FT-IR) spectrum, and particle morphologies were observed by scanning electron microscope (SEM). The results show that at lower concentration yellow croaker gill extract has no effect on calcium carbonate crystal polymorph. Calcite was obtained only. But the morphologies of calcite particle change with the increase of the concentration. The corners of the particle change from angular to curved. However, with the further increase of the concentration of yellow croaker gill extract, the calcium carbonate obtained is a mixture of calcite and vaterite. The vaterite component in the mixture rises with increasing concentration of extract solution, indicating that the proteins from the yellow croaker gill during growth play a crucial role in stabilizing and directing the crystal growth. Copyright © 2016 Elsevier B.V. All rights reserved.

Principal component analysis on a torus: Theory and application to protein dynamics

NASA Astrophysics Data System (ADS)

Sittel, Florian; Filk, Thomas; Stock, Gerhard

2017-12-01

A dimensionality reduction method for high-dimensional circular data is developed, which is based on a principal component analysis (PCA) of data points on a torus. Adopting a geometrical view of PCA, various distance measures on a torus are introduced and the associated problem of projecting data onto the principal subspaces is discussed. The main idea is that the (periodicity-induced) projection error can be minimized by transforming the data such that the maximal gap of the sampling is shifted to the periodic boundary. In a second step, the covariance matrix and its eigendecomposition can be computed in a standard manner. Adopting molecular dynamics simulations of two well-established biomolecular systems (Aib9 and villin headpiece), the potential of the method to analyze the dynamics of backbone dihedral angles is demonstrated. The new approach allows for a robust and well-defined construction of metastable states and provides low-dimensional reaction coordinates that accurately describe the free energy landscape. Moreover, it offers a direct interpretation of covariances and principal components in terms of the angular variables. Apart from its application to PCA, the method of maximal gap shifting is general and can be applied to any other dimensionality reduction method for circular data.

Method And Apparatus For Converting Hydrocarbon Fuel Into Hydrogen Gas And Carbon Dioxide

DOEpatents

Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.

2001-03-27

A hydrocarbon fuel reforming method is disclosed suitable for producing synthesis hydrogen gas from reactions with hydrocarbons fuels, oxygen, and steam. A first mixture of an oxygen-containing gas and a first fuel is directed into a first tube 108 to produce a first reaction reformate. A second mixture of steam and a second fuel is directed into a second tube 116 annularly disposed about the first tube 108 to produce a second reaction reformate. The first and second reaction reformates are then directed into a reforming zone 144 and subject to a catalytic reforming reaction. In another aspect of the method, a first fuel is combusted with an oxygen-containing gas in a first zone 108 to produce a reformate stream, while a second fuel under steam reforming in a second zone 116. Heat energy from the first zone 108 is transferred to the second zone 116.

A measurement model for general noise reaction in response to aircraft noise.

PubMed

Kroesen, Maarten; Schreckenberg, Dirk

2011-01-01

In this paper a measurement model for general noise reaction (GNR) in response to aircraft noise is developed to assess the performance of aircraft noise annoyance and a direct measure of general reaction as indicators of this concept. For this purpose GNR is conceptualized as a superordinate latent construct underlying particular manifestations. This conceptualization is empirically tested through estimation of a second-order factor model. Data from a community survey at Frankfurt Airport are used for this purpose (N=2206). The data fit the hypothesized factor structure well and support the conceptualization of GNR as a superordinate construct. It is concluded that noise annoyance and a direct measure of general reaction to noise capture a large part of the negative feelings and emotions in response to aircraft noise but are unable to capture all relevant variance. The paper concludes with recommendations for the valid measurement of community reaction and several directions for further research.

Direct observation of OH production from the ozonolysis of olefins

NASA Astrophysics Data System (ADS)

Donahue, Neil M.; Kroll, Jesse H.; Anderson, James G.; Demerjian, Kenneth L.

Ozone olefin reactions may be a significant source of OH in the urban atmosphere, but current evidence for OH production is indirect and contested. We report the first direct observation of OH radicals from the reaction of ozone with a series of olefins (ethene, isoprene, trans-2-butene and 2,3 dimethyl-2-butene) in 4-6 torr of nitrogen. Using LIF to directly observe the steady-state of OH produced by the initial ozone-olefin reaction and subsequently destroyed by the OH-olefin reaction, we are able to establish OH yields broadly consistent with indirect values. The identification of the OH is unequivocal, and there is no indication that it is produced by a secondary process. To support these observations, we present a complete ab-initio potential energy surface for the O3-ethene reaction, extending from the reactants to available products.

Motor Components in the Choice Reaction Time of Mildly Retarded Adults

ERIC Educational Resources Information Center

Brewer, N.

1978-01-01

The contributions of specific motor-coordination disabilities and general slowness of motor function to the choice reaction times (RTs) of 22 mildly retarded adults were examined in two experiments. (Author)

Chemisorption And Precipitation Reactions

EPA Science Inventory

The transport and bioavailability of chemical components within soils is, in part, controlled by partitioning between solids and solution. General terms used to describe these partitioning reactions include chemisorption and precipitation. Chemisorption is inclusive of the suit...

Observed side feeding in incomplete fusion dynamics in 16O + 160Gd reaction at energy ∼5.6 MeV/A: Spin distribution measurements

NASA Astrophysics Data System (ADS)

Ali, Rahbar; Afzal Ansari, M.; Singh, D.; Kumar, Rakesh; Singh, D. P.; Sharma, M. K.; Gupta, Unnati; Singh, B. P.; Shidling, P. D.; Negi, Dinesh; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.

2017-12-01

Spin distributions of various residues populated via complete fusion (CF) and incomplete fusion (ICF) reactions in the interaction of 16O with 160Gd at the projectile energy Eproj ∼ 5.6 MeV/A have been studied. The experimentally measured spin distributions of the residues associated with the ICF reactions are found to be distinctly different from those populated via the CF reactions. An attempt has been made to extract the side-feeding pattern from the spin distributions of CF and ICF reaction products. It has been observed that the CF products are strongly fed over a broad spin range. But, no side-feeding takes place in the low observed spins as low partial waves are strongly hindered in the fast α-emission channels (associated with ICF) in the forward direction. It has also been observed that the mean input angular momentum for direct α-emitting (ICF) channels is relatively higher than evaporation α-emitting (CF) channels, and it increases with direct α-multiplicity in forward direction.

Sphalerite is a geochemical catalyst for carbon−hydrogen bond activation

PubMed Central

Shipp, Jessie A.; Gould, Ian R.; Shock, Everett L.; Williams, Lynda B.; Hartnett, Hilairy E.

2014-01-01

Reactions among minerals and organic compounds in hydrothermal systems are critical components of the Earth’s deep carbon cycle, provide energy for the deep biosphere, and may have implications for the origins of life. However, there is limited information as to how specific minerals influence the reactivity of organic compounds. Here we demonstrate mineral catalysis of the most fundamental component of an organic reaction: the breaking and making of a covalent bond. In the absence of mineral, hydrothermal reaction of cis- and trans-1,2-dimethylcyclohexane is extremely slow and generates many products. In the presence of sphalerite (ZnS), however, the reaction rate increases dramatically and one major product is formed: the corresponding stereoisomer. Isotope studies show that the sphalerite acts as a highly specific heterogeneous catalyst for activation of a single carbon−hydrogen bond in the dimethylcyclohexanes. PMID:25071186

Sphalerite is a geochemical catalyst for carbon-hydrogen bond activation.

PubMed

Shipp, Jessie A; Gould, Ian R; Shock, Everett L; Williams, Lynda B; Hartnett, Hilairy E

2014-08-12

Reactions among minerals and organic compounds in hydrothermal systems are critical components of the Earth's deep carbon cycle, provide energy for the deep biosphere, and may have implications for the origins of life. However, there is limited information as to how specific minerals influence the reactivity of organic compounds. Here we demonstrate mineral catalysis of the most fundamental component of an organic reaction: the breaking and making of a covalent bond. In the absence of mineral, hydrothermal reaction of cis- and trans-1,2-dimethylcyclohexane is extremely slow and generates many products. In the presence of sphalerite (ZnS), however, the reaction rate increases dramatically and one major product is formed: the corresponding stereoisomer. Isotope studies show that the sphalerite acts as a highly specific heterogeneous catalyst for activation of a single carbon-hydrogen bond in the dimethylcyclohexanes.

Hypersensitivity reactions to vaccine constituents: a case series and review of the literature.

PubMed

Leventhal, Jonathan S; Berger, Emily M; Brauer, Jeremy A; Cohen, David E

2012-01-01

Vaccines are composed of immunogens, preservatives, adjuvants, antibiotics, and manufacturing by-products. Components of vaccines may rarely elicit adverse reactions in susceptible individuals, thus raising concerns regarding vaccine safety. In this report, we add to the medical literature 3 cases of cutaneous delayed-type hypersensitivity to the vaccine preservative aluminum. We provide a review of major constituents in vaccines that have elicited immediate-type or delayed-type hypersensitivity reactions and describe their clinical manifestations. We include a table of the Food and Drug Administration-approved vaccines, which lists the quantities of major components including ovalbumin (egg protein), gelatin, aluminum, neomycin, 2-phenoxyethanol, thimerosal, and formaldehyde. Our goals were to inform physicians on the variety of hypersensitivity reactions to common vaccines and to provide information on the choice of vaccines in patients with suspected hypersensitivity.

Individual Differences in Components of Reaction Time Distributions and Their Relations to Working Memory and Intelligence

ERIC Educational Resources Information Center

Schmiedek, Florian; Oberauer, Klaus; Wilhelm, Oliver; Suss, Heinz-Martin; Wittmann, Werner W.

2007-01-01

The authors bring together approaches from cognitive and individual differences psychology to model characteristics of reaction time distributions beyond measures of central tendency. Ex-Gaussian distributions and a diffusion model approach are used to describe individuals' reaction time data. The authors identified common latent factors for each…

Vaccine hypersensitivity--update and overview.

PubMed

Fritsche, Philipp J; Helbling, Arthur; Ballmer-Weber, Barbara K

2010-05-01

Concerns about possible reactions to vaccines or vaccinations are frequently raised. However, the rate of reported vaccine-induced adverse events is low and ranges between 4.8-83.0 per 100,000 doses of the most frequently used vaccines. The number of true allergic reactions to routine vaccines is not known; estimations range from 1 per 500,000 to 1 per 1,000,000 doses for most vaccines. When allergens such as gelatine or egg proteins are components of the formulation, the rate for serious allergic reactions may be higher. Nevertheless, anaphylactic, potentially life-threatening reactions to vaccines are still a rare event (approximately 1 per 1,500,000 doses). The variety of reported vaccine-related adverse events is broad. Most frequently, reactions to vaccines are limited to the injection site and result from a non specific activation of the inflammatory system by, for example, aluminium salts or the active microbial components. If allergy is suspected, an accurate examination followed by algorithms is the key for correct diagnosis, treatment and the decision regarding revaccination in patients with immediate-type reactions to vaccines.

NiFe layered double hydroxide/reduced graphene oxide nanohybrid as an efficient bifunctional electrocatalyst for oxygen evolution and reduction reactions

NASA Astrophysics Data System (ADS)

Zhan, Tianrong; Zhang, Yumei; Liu, Xiaolin; Lu, SiSi; Hou, Wanguo

2016-11-01

Highly active and low-cost bifunctional electrocatalysts for oxygen evolution and reduction reactions (OER and ORR) hold a heart position for the renewable energy technologies such as metal-air batteries and fuel cells. Here, we reported the synthesis of NiFe layered double hydroxide/reduced graphene oxide (NiFe-LDH/rGO) nanohybrid via the facile solvothermal method followed by chemical reduction. The template role of surfactant and the hybridization of rGO supplied the NiFe-LDH/rGO catalyst with a porous nanostructure and an enhanced conductivity, favoring both mass transport and charge communication of electrocatalytic reactions. The NiFe-LDH/rGO composite not only displayed highly efficient OER activity in alkaline solution with a low onset overpotential of 240 mV, but also only needed an overpotential of 250 mV to reach the 10 mA cm-2 current density. The NiFe-LDH/rGO nanohybrid also offered excellent ORR catalytic activity with onset potential at 0.796 V in alkaline media. The rotating-disk and rotating-ring-disk electrodes both revealed that the ORR on NiFe-LDH/rGO mainly involved a direct four-electron reaction pathways accompanying part of the two-electron process. The excellent bifunctional activity of the NiFe-LDH/rGO nanohybrid could be attributed to the synergistic effects of rGO and NiFe-LDH components due to the strongly coupled interactions.

Integration of whole-cell reaction and product isolation: Highly hydrophobic solvents promote in situ substrate supply and simplify extractive product isolation.

PubMed

Leis, Dorothea; Lauß, Bernhard; Macher-Ambrosch, Robert; Pfennig, Andreas; Nidetzky, Bernd; Kratzer, Regina

2017-09-10

Product isolation from aqueous-organic reaction mixtures that contain high concentrations of whole cells constitutes a challenging task in bioprocessing. Stirring of the biphasic reaction media leads to the formation of solvent droplets coated by cells and other surface active components and an emulsion forms. We used an early focus on phase separation to simplify a whole-cell bioreduction. Octanol, heptanol, hexanol, hexane and dipropylether were tested as co-solvents in the E. coli catalyzed reduction of o-chloroacetophenone. All solvents showed very similar performance in bioreductions and highest yields were obtained with low organic-to-aqueous phase ratios. Reaction mixtures were directly investigated for organic-phase recovery. Phase separation was optimized in small-scale settling experiments and confirmed by the isolation of 20.4g (S)-1-(2-chlorophenyl)ethanol from a 0.5L batch reduction containing 40g CDW /L whole-cell catalyst. Solvent consumption during product isolation could be halved by the simple addition of sodium hydroxide prior to product extraction. Basification to pH 13.5 and three extraction steps with a total of 1.2v/v hexane led to an isolated yield of 87% (97% reduction yield). A general emulsion destabilizing effect under harsh conditions, as extreme pH values and presence of toxic reactants, was observed. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Cortical sources of ERP in prosaccade and antisaccade eye movements using realistic source models

PubMed Central

Richards, John E.

2013-01-01

The cortical sources of event-related-potentials (ERP) using realistic source models were examined in a prosaccade and antisaccade procedure. College-age participants were presented with a preparatory interval and a target that indicated the direction of the eye movement that was to be made. In some blocks a cue was given in the peripheral location where the target was to be presented and in other blocks no cue was given. In Experiment 1 the prosaccade and antisaccade trials were presented randomly within a block; in Experiment 2 procedures were compared in which either prosaccade and antisaccade trials were mixed in the same block, or trials were presented in separate blocks with only one type of eye movement. There was a central negative slow wave occurring prior to the target, a slow positive wave over the parietal scalp prior to the saccade, and a parietal spike potential immediately prior to saccade onset. Cortical source analysis of these ERP components showed a common set of sources in the ventral anterior cingulate and orbital frontal gyrus for the presaccadic positive slow wave and the spike potential. In Experiment 2 the same cued- and non-cued blocks were used, but prosaccade and antisaccade trials were presented in separate blocks. This resulted in a smaller difference in reaction time between prosaccade and antisaccade trials. Unlike the first experiment, the central negative slow wave was larger on antisaccade than on prosaccade trials, and this effect on the ERP component had its cortical source primarily in the parietal and mid-central cortical areas contralateral to the direction of the eye movement. These results suggest that blocked prosaccade and antisaccade trials results in preparatory or set effects that decreases reaction time, eliminates some cueing effects, and is based on contralateral parietal-central brain areas. PMID:23847476

Direct radiative effect by multicomponent aerosol over China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Xin; Song, Yu; Zhao, Chun

The direct radiative effect (DRE) of multiple aerosol species (sulfate, nitrate, ammonium, black carbon (BC), organic carbon (OC), and mineral aerosol) and their spatiotemporal variations over China were investigated using a fully coupled meteorology–chemistry model (WRF-Chem) for the entire year of 2006. We made modifications to improve model performance, including updating land surface parameters, improving the calculation of transition metal-catalyzed oxidation of SO 2, and adding in heterogeneous reactions between mineral aerosol and acid gases. The modified model well reproduced the magnitude, seasonal pattern, and spatial distribution of the measured meteorological conditions, concentrations of PM 10 and its components, andmore » aerosol optical depth (AOD). A diagnostic iteration method was used to estimate the overall DRE of aerosols and contributions from different components. At the land surface, all kinds of aerosol species reduced the incident net radiation flux with a total DRE of 10.2 W m -2 over China. Aerosols significantly warm the atmosphere with the national mean DRE of +10.8 W m -2. BC was the leading radiative-heating component (+8.7 W m -2), followed by mineral aerosol (+1.1 W m -2). At the top of the atmosphere (TOA), BC introduced the largest radiative perturbation (+4.5 W m -2), followed by sulfate (-1.4 W m -2). The overall perturbation of aerosols on radiation transfer is quite small over China, demonstrating the counterbalancing effect between scattering and adsorbing aerosols. Aerosol DRE at the TOA had distinct seasonality, generally with a summer maximum and winter minimum, mainly determined by mass loadings, hygroscopic growth, and incident radiation flux.« less

Enantioselective addition of nitromethane to 2-acylpyridine N-oxides. Expanding the generation of quaternary stereocenters with the Henry reaction.

PubMed

Holmquist, Melireth; Blay, Gonzalo; Muñoz, M Carmen; Pedro, José R

2014-02-21

The direct asymmetric Henry reaction with prochiral ketones, leading to tertiary nitroaldols, is an elusive reaction so far limited to a reduced number of reactive substrates such as trifluoromethyl ketones or α-keto carbonyl compounds. Expanding the scope of this important reaction, the direct asymmetric addition of nitromethane to 2-acylpyridine N-oxides catalyzed by a BOX-Cu(II) complex to give the corresponding pyridine-derived tertiary nitroaldols having a quaternary stereogenic center with variable yields and good enantioselectivity, is described.

Microscale Thermite Reactions.

ERIC Educational Resources Information Center

Arnaiz, Francisco J.; Aguado, Rafael; Arnaiz, Susana

1998-01-01

Describes the adaptation of thermite (aluminum with metal oxides) reactions from whole-class demonstrations to student-run micro-reactions. Lists detailed directions and possible variations of the experiment. (WRM)

Ultrasound mediated, iodine catalyzed green synthesis of novel 2-amino-3-cyano-4H-pyran derivatives.

PubMed

Tabassum, Sumaiya; Govindaraju, Santhosh; Khan, Riyaz-ur-Rahaman; Pasha, Mohamed Afzal

2015-05-01

An efficient synthesis of a novel series of twelve substituted 2-amino-3-cyano-4H-pyran derivatives was achieved by a one-pot three-component cyclocondensation reaction of heteroaryl aldehydes, malononitrile and active methylene compounds catalyzed by iodine in aqueous medium under ultrasound irradiation. In comparison with conventional methods, our protocol is convenient and offers several advantages, such as shorter reaction time, higher yields, milder conditions and environmental friendliness. We have herein successfully demonstrated the synergistic outcome of multi-component reaction (MCR) and sonication to offer a facile route for the design of these derivatives. Copyright © 2014 Elsevier B.V. All rights reserved.

[The noncoherent components of evoked brain activity].

PubMed

Kovalev, V P; Novototskiĭ-Vlasov, V Iu

1998-01-01

Poststimulus spectral EEG changes and their correlation with evoked potential (EP) were analyzed. The non-stationary components of the brain evoked activity were revealed in 32 volunteers during simple motor reaction and choice reaction to visual stimuli. This nonstationary activity was manifested in poststimulus changes in the mean wave half-period duration (MWHPD) and mean wave half-period power of the delta- and beta-frequency oscillations computed in the EEG realizations after the EP subtraction. The latencies of high-frequency EP components fell into the intervals of the MWHPD decrease and increase in the power of beta-oscillations, and the latencies of low-frequency EP components coincided with the intervals of the MWHPD increase and decrease in the power of delta and beta-oscillations, which pointed to correlation of these changes with the EP.

The path to achieving molecular dispersion in an extremely dense reactive mixture

NASA Astrophysics Data System (ADS)

Patel, Jigneshkumar; Xiang, Zou; Hsu, Shaw; Schoch, Andrew

2015-03-01

In any multicomponent reactive system, a uniform and continuous dispersion of reactants is necessary to achieve a complete reaction. In this study, we have examined the role of one additional component to disperse two seemingly unlikely reactants, including a highly crystalline hexamethylenetetramine (hexa) and strongly hydrogen bonded phenol formaldehyde resin. By combining information from NMR, infrared spectroscopy and differential scanning calorimetry, we were able to decipher the role of specific intermolecular interactions in order for this additional component to dissolve the highly crystalline hexa and to plasticize the phenol formaldehyde resin in this crosslinking reaction. It is clear that the presence of the third component increased the segmental mobility, disrupted the hydrogen bonded matrix, and freed the hydroxyl units, which further increased the solubility of hexa. Both the endothermic and exothermic transitions are accounted for in the calorimetric data obtained. For the first time, it is possible to understand the miscibility behavior of this multicomponent system. By designing the additional component to form a hydrogen bond with one or more N of the highly symmetric hexamethylenetetramine, it is then possible to obtain the effective molar ratio of each component needed to complete the crosslinking reaction efficiently. The understanding of this system is applicable to a broad range of reactive systems.

DIRECT SYNTHESIS OF TERTIARY AMINES IN WATER USING MICROWAVES

EPA Science Inventory

A direct synthesis of tertiary amines is presented that proceeds expeditiously via N-alkylation of amines using alkyl halides in alkaline aqueous medium. This environmentally benign reaction is accelerated upon exposure to microwave irradiation resulting in shortened reaction tim...

Recent developments in Cope-type hydroamination reactions of hydroxylamine and hydrazine derivatives.

PubMed

Beauchemin, André M

2013-11-07

Cope-type hydroaminations are versatile for the direct amination of alkenes, alkynes and allenes using hydroxylamines and hydrazine derivatives. These reactions occur via a concerted, 5-membered cyclic transition state that is the microscopic reverse of the Cope elimination. This article focuses on recent developments, including intermolecular variants, directed reactions, and asymmetric variants using aldehydes as tethering catalysts, and their applications in target-oriented synthesis.

Direct asymmetric aldol reactions between aldehydes and ketones catalyzed by L-tryptophan in the presence of water.

PubMed

Jiang, Zhaoqin; Yang, Hui; Han, Xiao; Luo, Jie; Wong, Ming Wah; Lu, Yixin

2010-03-21

Primary amino acids and their derivatives were investigated as catalysts for the direct asymmetric aldol reactions between ketones and aldehydes in the presence of water, and L-tryptophan was shown to be the best catalyst. Solvent effects, substrate scope and the influence of water on the reactions were investigated. Quantum chemical calculations were performed to understand the origin of the observed stereoselectivity.

Rotational joint assembly and method for constructing the same

NASA Technical Reports Server (NTRS)

Bandera, Pablo (Inventor); Buchele, Paul (Inventor)

2012-01-01

A rotational joint assembly and a method for constructing a rotational joint assembly are provided. The rotational joint assembly includes a first rotational component, a second rotational component coupled to the first rotational component such that the second rotational component is rotatable relative to the first rotational component in first and second rotational directions about an axis, and a flexure member, being deflectable in first and second deflection directions, coupled to at least one of the first and second rotational components such that when the second rotational component is rotated relative to the first rotational component in each of the first and second rotational directions about the axis, the flexure member is deflected in the first deflection direction and exerts a force on the second rotational component opposing the rotation.

Energy partitioning in polyatomic chemical reactions: Quantum state resolved studies of highly exothermic atom abstraction reactions from molecules in the gas phase and at the gas-liquid interface

NASA Astrophysics Data System (ADS)

Zolot, Alexander M.

This thesis recounts a series of experiments that interrogate the dynamics of elementary chemical reactions using quantum state resolved measurements of gas-phase products. The gas-phase reactions F + HCl → HF + Cl and F + H2O → HF + OH are studied using crossed supersonic jets under single collision conditions. Infrared (IR) laser absorption probes HF product with near shot-noise limited sensitivity and high resolution, capable of resolving rovibrational states and Doppler lineshapes. Both reactions yield inverted vibrational populations. For the HCl reaction, strongly bimodal rotational distributions are observed, suggesting microscopic branching of the reaction mechanism. Alternatively, such structure may result from a quantum-resonance mediated reaction similar to those found in the well-characterized F + HD system. For the H2O reaction, a small, but significant, branching into v = 2 is particularly remarkable because this manifold is accessible only via the additional center of mass collision energy in the crossed jets. Rotationally hyperthermal HF is also observed. Ab initio calculations of the transition state geometry suggest mechanisms for both rotational and vibrational excitation. Exothermic chemical reaction dynamics at the gas-liquid interface have been investigated by colliding a supersonic jet of F atoms with liquid squalane (C30H62), a low vapor pressure hydrocarbon compatible with the high vacuum environment. IR spectroscopy provides absolute HF( v,J) product densities and Doppler resolved velocity component distributions perpendicular to the surface normal. Compared to analogous gas-phase F + hydrocarbon reactions, the liquid surface is a more effective "heat sink," yet vibrationally excited populations reveal incomplete thermal accommodation with the surface. Non-Boltzmann J-state populations and hot Doppler lineshapes that broaden with HF excitation indicate two competing scattering mechanisms: (i) a direct reactive scattering channel, whereby newly formed molecules leave the surface without equilibrating, and (ii) a partially accommodated fraction that shares vibrational, rotational, and translational energy with the liquid surface before returning to the gas phase. Finally, a velocity map ion imaging apparatus has been implemented to investigate reaction dynamics in crossed molecular beams. Resonantly enhanced multiphoton ionization (REMPI) results in rotational, vibrational, and electronic state selectivity. Velocity map imaging measurements provide differential cross sections and information about the internal energy distribution of the undetected collision partner.

Interplay of spherical closed shells and N /Z asymmetry in quasifission dynamics

NASA Astrophysics Data System (ADS)

Mohanto, G.; Hinde, D. J.; Banerjee, K.; Dasgupta, M.; Jeung, D. Y.; Simenel, C.; Simpson, E. C.; Wakhle, A.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; Palshetkar, C. S.; Rafferty, D. C.

2018-05-01

Background: Quasifission (QF) has gained tremendous importance in heavy-ion nuclear physics research because of its strong influence on superheavy-element synthesis. Collisions involving closed-shell nuclei in the entrance channel are found to affect the QF reaction mechanism. Hence, it is important to improve the understanding of their effect on QF. Apart from that, some recent studies show that the difference in N /Z of reaction partners influences the reaction dynamics. Since heavier doubly magic nuclei have different N /Z than lighter doubly magic nuclei, it is important to understand the effect of N /Z mismatch as well as the effect of shell closures. Purpose: To investigate the effect of entrance-channel shell closures and N /Z asymmetry on QF. The reactions were chosen to decouple these effects from the contributions of other entrance-channel parameters. Method: Fission fragment mass-angle distributions were measured using the CUBE fission spectrometer, consisting of two large area position-sensitive multi-wire proportional counters (MWPCs), for five reactions, namely, 50Cr+208Pb , 52Cr+Pb,208206 , 54Cr+Pb,208204 . Result: Two components were observed in the measured fragment mass angle distribution, a fast mass-asymmetric quasifission and a slow mass-symmetric component having a less significant mass-angle correlation. The ratio of these components was found to depend on spherical closed shells in the entrance channel nuclei and the magnitude of the N /Z mismatch between the two reaction partners, as well as the beam energy. Conclusions: Entrance-channel spherical closed shells can enhance compound nucleus formation provided the N /Z asymmetry is small. Increase in the N /Z asymmetry is expected to destroy the effect of entrance-channel spherical closed shells, through nucleon transfer reactions.

Polycyclic aromatic hydrocarbon formation during the gasification of sewage sludge in sub- and supercritical water: Effect of reaction parameters and reaction pathways.

PubMed

Gong, Miao; Wang, Yulan; Fan, Yujie; Zhu, Wei; Zhang, Huiwen; Su, Ying

2018-02-01

The formation of polycyclic aromatic hydrocarbon is a widespread issue during the supercritical water gasification of sewage sludge, which directly reduces the gasification efficiency and restricts the technology practical application. The changes of the concentrations and forms as well as the synthesis rate of polycyclic aromatic hydrocarbons in the residues from supercritical water gasification of dewatered sewage sludge were investigated to understand influence factors and the reaction pathways. Results showed that the increase of reaction temperature during the heating period favours directly concentration of polycyclic aromatic hydrocarbon (especially higher-molecular-weight), especially when it raise above 300 °C. Lower heating and cooling rate essentially extend the total reaction time. Higher polycyclic aromatic hydrocarbon concentration and higher number of rings were generally promoted by lower heating and cooling rate, longer reaction time and higher reaction temperature. The lower-molecular-weight polycyclic aromatic hydrocarbons can be directly generated through the decomposition of aromatic-containing compounds in sewage sludge, as well as 3-ring and 4-ring polycyclic aromatic hydrocarbons can be formed by aromatization of steroids. Possible mechanisms of reaction pathways of supercritical water gasification of sewage sludge were also proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Poly(n-hexyl methacrylate) polymerization in three-component microemulsion stabilized by a cationic surfactant.

PubMed

Katime, Issa; Arellano, Jesús; Schulz, Pablo

2006-04-15

The polymerization of n-hexyl methacrylate (n-HMA) in three-component microemulsion stabilized with dodecyltrimethylammonium bromide (DTAB) is reported as a function of monomer and initiator concentrations and temperature. The obtained latices were bluish, transparent, and translucent. Particle sizes and molar masses were on the order of 20 nm and 3 x 10(6) g/mol, respectively. In all cases, high reaction rates and final conversions of 98% were obtained. Polymerization temperature has a strong effect on reaction rate and conversion.

Copper-catalyzed three- five- or seven-component coupling reactions: the selective synthesis of cyanomethylamines, N,N-bis(cyanomethyl)amines and N,N'-bis(cyanomethyl)methylenediamines based on a Strecker-type synthesis.

PubMed

Sakai, Norio; Takahashi, Nobuaki; Inoda, Daiki; Ikeda, Reiko; Konakahara, Takeo

2013-10-10

We have demonstrated that a cooperative catalytic system comprised of CuCl and Cu(OTf)(2) could be used to effectively catalyse the three-, five- and seven-component coupling reactions of aliphatic or aromatic amines, formaldehyde, and trimethylsilyl cyanide (TMSCN), and selectively produce in good yields the corresponding cyanomethylamines, N,N-bis(cyanomethyl)amines and N,N'-bis(cyanomethyl)methylenediamines.

Biodiesel production by direct transesterification of microalgal biomass with co-solvent.

PubMed

Zhang, Yan; Li, Ya; Zhang, Xu; Tan, Tianwei

2015-11-01

In this study, a direct transesterification process using 75% ethanol and co-solvent was studied to reduce the energy consumption of lipid extraction process and improve the conversion yield of the microalgae biodiesel. The addition of a certain amount of co-solvent (n-hexane is most preferable) was required for the direct transesterification of microalgae biomass. With the optimal reaction condition of n-hexane to 75% ethanol volume ratio 1:2, mixed solvent dosage 6.0mL, reaction temperature 90°C, reaction time 2.0h and catalyst volume 0.6mL, the direct transesterification process of microalgal biomass resulted in a high conversion yield up to 90.02±0.55wt.%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of astrophysical 7Be(p, γ)8B reaction rates from the 7Li(d, p)8Li reaction

NASA Astrophysics Data System (ADS)

Du, XianChao; Guo, Bing; Li, ZhiHong; Pang, DanYang; Li, ErTao; Liu, WeiPing

2015-06-01

The 7Be(p, γ)8B reaction plays a central role not only in the evaluation of solar neutrino fluxes but also in the evolution of the first stars. Study of this reaction requires the asymptotic normalization coefficient (ANC) for the virtual decay 8B g.s. → 7Be + p. By using the charge symmetry relation, we obtain this proton ANC with the single neutron ANC of 8Li g.s. →7Li + n, which is determined with the distorted wave Born approximation (DWBA) and adiabatic distorted wave approximation (ADWA) analysis of the 7Li(d, p)8Li angular distribution. The astrophysical S-factors and reaction rates of the direct capture process in the 7Be(p, γ)8B reaction are further deduced at energies of astrophysical relevance. The astrophysical S-factor at zero energy for direct capture, S 17(0), is derived to be (19.9 ± 3.5) eV b in good agreement with the most recent recommended value. The contributions of the 1+ and 3+ resonances to the S-factor and reaction rate are also evaluated. The present result demonstrates that the direct capture dominates the 7Be(p, γ)8B reaction in the whole temperature range. This work provides an independent examination to the current results of the 7Be(p, γ)8B reaction.

ELSA- The European Levitated Spherical Actruator

NASA Astrophysics Data System (ADS)

Ruiz, M.; Serin, J.; Telteu-Nedelcu, D.; De La Vallee Poussin, H.; Onillon, E.; Rossini, L.

2014-08-01

The reaction sphere is a magnetic bearing spherical actuator consisting of a permanent magnet spherical rotor that can be accelerated in any direction. It consists of an 8-pole permanent magnet spherical rotor that is magnetically levitated and can be accelerated about any axis by a 20-pole stator with electromagnets. The spherical actuator is proposed as a potential alternative to traditional momentum exchange devices such as reaction wheels (RWs) or control moment gyroscopes (CMGs). This new actuator provides several benefits such as reduced mass and power supply allocated to the attitude and navigation unit, performance gain, and improved reliability due to the absence of mechanical bearings. The paper presents the work done on the levitated spherical actuator and more precisely the electrical drive including its control unit and power parts. An elegant breadboard is currently being manufactured within the frame of an FP7 project. This project also comprises a feasibility study to show the feasibility of integrating such a system on a flight platform and to identify all the challenges to be solved in terms of technology or components to be developed.

Electrochemical Transfer of S Between Molten Steel and Molten Slag

NASA Astrophysics Data System (ADS)

Kim, Dong-Hyun; Kim, Wook; Kang, Youn-Bae

2018-06-01

S transfer between molten steel and molten slag was investigated in view of the electrochemical character of S transfer. C-saturated molten steel containing S was allowed to react with CaO-SiO2-Al2O3-MgO slag at 1673 K (1400 °C) until the two phases arrive at a chemical equilibrium. The application of an electric field of constant current through graphite electrodes lowered the S content in the molten steel below its chemical equilibrium level, and the system arrived at a new equilibrium level (electrochemical equilibrium). However, subsequent shutting off of the electric field did not lead to the system reverting to the original chemical equilibrium: reversion of S was observed but to a limited extent. The application of an electric field of opposite direction or flowing of CO gas allowed significant reversion of S. Side reactions (decomposition of oxide components) were observed, and these were considered to be coupled to the transfer of S. An electrochemical reaction mechanism was proposed based on the experimental observations found in the present study.

Thermal ageing and short-range ordering of Alloy 690 between 350 and 550 °C

NASA Astrophysics Data System (ADS)

Mouginot, Roman; Sarikka, Teemu; Heikkilä, Mikko; Ivanchenko, Mykola; Ehrnstén, Ulla; Kim, Young Suk; Kim, Sung Soo; Hänninen, Hannu

2017-03-01

Thermal ageing of Alloy 690 triggers an intergranular (IG) carbide precipitation and is known to promote an ordering reaction causing lattice contraction. It may affect the long-term primary water stress corrosion cracking (PWSCC) resistance of pressurized water reactor (PWR) components. Four conditions of Alloy 690 (solution annealed, cold-rolled and/or heat-treated) were aged between 350 and 550 °C for 10 000 h and characterized. Although no direct observation of ordering was made, variations in hardness and lattice parameter were attributed to the formation of short-range ordering (SRO) in all conditions with a peak level at 420 °C, consistent with the literature. Prior heat treatment induced ordering before thermal ageing. At higher temperatures, stress relaxation, recrystallization and α-Cr precipitation were observed in the cold-worked samples, while a disordering reaction was inferred in all samples based on a decrease in hardness. IG precipitation of M23C6 carbides increased with increasing ageing temperature in all conditions, as well as diffusion-induced grain boundary migration (DIGM).

Neutron capture cross section of {sup 14}C of astrophysical interest studied by Coulomb breakup of {sup 15}C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, T.; Fukuda, N.; Aoi, N.

2009-03-15

The neutron capture reaction on {sup 14}C leading to the {sup 15}C ground state, which plays an important role in various nucleosynthesis processes, has been studied using the Coulomb breakup of {sup 15}C on a Pb target at 68 MeV/nucleon. The breakup cross section has been converted into the energy-dependent neutron capture cross section using the principle of detailed balance. The energy spectrum shows typical p-wave neutron capture characteristics, which is explained by the fact that the ground state of {sup 15}C possesses a strong single-particle s-wave component and a moderate-sized neutron halo structure. The capture cross section for themore » {sup 14}C(n,{gamma}){sup 15}C reaction derived from the present experiment has been found to be consistent with the most recent data, directly measured using a {sup 14}C target. This result assures the validity of the Coulomb breakup method in deriving the neutron capture cross section for neutron-rich nuclei.« less

Recovery of lead from lead paste in spent lead acid battery by hydrometallurgical desulfurization and vacuum thermal reduction.

PubMed

Ma, Yunjian; Qiu, Keqiang

2015-06-01

Lead sulfate, lead oxides and lead metal are the main component of lead paste in spent lead acid battery. When lead sulfate was desulfurized and transformed into lead carbonate by sodium carbonate, lead metal and lead oxides remained unchanged. Lead carbonate is easily decomposed to lead oxide and carbon dioxide under high temperature. Namely, vacuum thermal process is the reduction reaction of lead oxides. A compatible environmental process consisted of hydrometallurgical desulfurization and vacuum thermal reduction to recycle lead was investigated in this research. Lead paste was firstly desulfurized with sodium carbonate, by which, the content of sulfur declined from 7.87% to 0.26%. Then, the desulfurized lead paste was reduced by charcoal under vacuum. Under the optimized reaction conditions, i.e., vacuum thermal reduction at temperature 850°C under 20 Pa for 45 min, a 22.11×10(-2) g cm(-2) min(-1) reduction rate, and a 98.13% direct recovery ratio of fine lead (99.77%) had been achieved, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exact model reduction of combinatorial reaction networks

PubMed Central

Conzelmann, Holger; Fey, Dirk; Gilles, Ernst D

2008-01-01

Background Receptors and scaffold proteins usually possess a high number of distinct binding domains inducing the formation of large multiprotein signaling complexes. Due to combinatorial reasons the number of distinguishable species grows exponentially with the number of binding domains and can easily reach several millions. Even by including only a limited number of components and binding domains the resulting models are very large and hardly manageable. A novel model reduction technique allows the significant reduction and modularization of these models. Results We introduce methods that extend and complete the already introduced approach. For instance, we provide techniques to handle the formation of multi-scaffold complexes as well as receptor dimerization. Furthermore, we discuss a new modeling approach that allows the direct generation of exactly reduced model structures. The developed methods are used to reduce a model of EGF and insulin receptor crosstalk comprising 5,182 ordinary differential equations (ODEs) to a model with 87 ODEs. Conclusion The methods, presented in this contribution, significantly enhance the available methods to exactly reduce models of combinatorial reaction networks. PMID:18755034

Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

PubMed

Herrmann, Hans W; Mack, Joseph M; Young, Carlton S; Malone, Robert M; Stoeffl, Wolfgang; Horsfield, Colin J

2008-10-01

Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.

Photon Energy Threshold in Direct Photocatalysis with Metal Nanoparticles: Key Evidence from the Action Spectrum of the Reaction.

PubMed

Sarina, Sarina; Jaatinen, Esa; Xiao, Qi; Huang, Yi Ming; Christopher, Philip; Zhao, Jin Cai; Zhu, Huai Yong

2017-06-01

By investigating the action spectra (the relationship between the irradiation wavelength and apparent quantum efficiency of reactions under constant irradiance) of a number of reactions catalyzed by nanoparticles including plasmonic metals, nonplasmonic metals, and their alloys at near-ambient temperatures, we found that a photon energy threshold exists in each photocatalytic reaction; only photons with sufficient energy (e.g., higher than the energy level of the lowest unoccupied molecular orbitals) can initiate the reactions. This energy alignment (and the photon energy threshold) is determined by various factors, including the wavelength and intensity of irradiation, molecule structure, reaction temperature, and so forth. Hence, distinct action spectra were observed in the same type of reaction catalyzed by the same catalyst due to a different substituent group, a slightly changed reaction temperature. These results indicate that photon-electron excitations, instead of the photothermal effect, play a dominant role in direct photocatalysis of metal nanoparticles for many reactions.

Stereospecific synthesis of syn-α-oximinoamides by a three-component reaction of isocyanides, syn-chlorooximes, and carboxylic acids.

PubMed

Pirali, Tracey; Mossetti, Riccardo; Galli, Simona; Tron, Gian Cesare

2011-07-15

A stereospecific multicomponent reaction among isocyanides, syn-chlorooximes, and carboxylic acids provides an efficient synthesis of biologically relevant syn-α-oximinoamides. © 2011 American Chemical Society

A cascade reaction network mimicking the basic functional steps of adaptive immune response

NASA Astrophysics Data System (ADS)

Han, Da; Wu, Cuichen; You, Mingxu; Zhang, Tao; Wan, Shuo; Chen, Tao; Qiu, Liping; Zheng, Zheng; Liang, Hao; Tan, Weihong

2015-10-01

Biological systems use complex ‘information-processing cores’ composed of molecular networks to coordinate their external environment and internal states. An example of this is the acquired, or adaptive, immune system (AIS), which is composed of both humoral and cell-mediated components. Here we report the step-by-step construction of a prototype mimic of the AIS that we call an adaptive immune response simulator (AIRS). DNA and enzymes are used as simple artificial analogues of the components of the AIS to create a system that responds to specific molecular stimuli in vitro. We show that this network of reactions can function in a manner that is superficially similar to the most basic responses of the vertebrate AIS, including reaction sequences that mimic both humoral and cellular responses. As such, AIRS provides guidelines for the design and engineering of artificial reaction networks and molecular devices.

Cosmetic components causing contact urticaria: a review and update.

PubMed

Verhulst, Lien; Goossens, An

2016-12-01

Immediate skin reactions are common in dermatological practice, but may often be overlooked. The main objective of this article is to provide an update of the literature concerning immediate-type reactions or contact urticaria/contact urticaria syndrome caused by cosmetic ingredients in terms of immediate clinical symptoms, positive reactions following open, scratch or, most often, prick testing, and sometimes the detection of specific IgE antibodies. To this end, a selective search in different medical literature databases was performed. This yielded a list of cosmetic ingredients causing immediate reactions, including hair dyes and bleaches, preservatives, fragrance and aroma chemicals, sunscreens, hair glues, plant-derived and animal-derived components, permanent makeup and tattoos, glycolic acid peel, lip plumper, and alcohols. Many of the reported cases, however, lack appropriate controls and detailed investigation. Contact urticaria may occur with or without systemic symptoms, which are sometimes life-threatening. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Method And Apparatus For Converting Hydrocarbon Fuel Into Hydrogen Gas And Carbon Dioxide

DOEpatents

Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.

2000-09-26

A method is disclosed for synthesizing hydrogen gas from hydrocarbon fuel. A first mixture of steam and a first fuel is directed into a first tube 208 to subject the first mixture to a first steam reforming reaction in the presence of a first catalyst 214. A stream of oxygen-containing gas is pre-heated by transferring heat energy from product gases. A second mixture of the pre-heated oxygen-containing gas and a second fuel is directed into a second tube 218 disposed about the first tube 208 to subject the second mixture to a partial oxidation reaction and to provide heat energy for transfer to the first tube 208. A first reaction reformate from the first tube 208 and a second reaction reformate from the second tube 218 are directed into a third tube 224 disposed about the second tube 218 to subject the first and second reaction reformates to a second steam reforming reaction, wherein heat energy is transferred to the third tube 224 from the second tube 218.

Reprint of: Reaction measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

NASA Astrophysics Data System (ADS)

Chipps, K. A.

2018-01-01

Explosive stellar environments are sometimes driven by nuclear reactions on short-lived, radioactive nuclei. These reactions often drive the stellar explosion, alter the observable light curves produced, and dictate the final abundances of the isotopes created. Unfortunately, many reaction rates at stellar temperatures cannot be directly measured in the laboratory, due to the physical limitations of ultra-low cross sections and high background rates. An additional complication arises because many of the important reactions involve radioactive nuclei which have lifetimes too short to be made into a target. As such, direct reactions require very intense and pure beams of exotic nuclei. Indirect approaches with both stable and radioactive beams can, however, provide crucial information on the nuclei involved in these astrophysical reactions. A major development toward both direct and indirect studies of nuclear reactions rates is the commissioning of the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) supersonic gas jet target. The JENSA system provides a pure, homogeneous, highly localized, dense, and robust gaseous target for radioactive ion beam studies. Charged-particle reactions measurements made with gas jet targets can be cleaner and display better resolution than with traditional targets. With the availability of pure and localized gas jet targets in combination with developments in exotic radioactive ion beams and next-generation detector systems, the range of reaction studies that are experimentally possible is vastly expanded. Various representative cases will be discussed.

Exploring the hidden interior of the Earth with directional neutrino measurements

DOE PAGES

Leyton, Michael; Dye, Stephen; Monroe, Jocelyn

2017-07-10

Roughly 40% of the Earth’s total heat flow is powered by radioactive decays in the crust and mantle. Geo-neutrinos produced by these decays provide important clues about the origin, formation and thermal evolution of our planet, as well as the composition of its interior. Previous measurements of geo-neutrinos have all relied on the detection of inverse beta decay reactions, which are insensitive to the contribution from potassium and do not provide model-independent information about the spatial distribution of geo-neutrino sources within the Earth. Here in this paper we present a method for measuring previously unresolved components of Earth’s radiogenic heatingmore » using neutrino-electron elastic scattering and low-background, direction-sensitive tracking detectors.We calculate the exposures needed to probe various contributions to the total geo-neutrino flux, specifically those associated to potassium, the mantle and the core. The measurements proposed here chart a course for pioneering exploration of the veiled inner workings of the Earth.« less

Exploring the hidden interior of the Earth with directional neutrino measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leyton, Michael; Dye, Stephen; Monroe, Jocelyn

Roughly 40% of the Earth’s total heat flow is powered by radioactive decays in the crust and mantle. Geo-neutrinos produced by these decays provide important clues about the origin, formation and thermal evolution of our planet, as well as the composition of its interior. Previous measurements of geo-neutrinos have all relied on the detection of inverse beta decay reactions, which are insensitive to the contribution from potassium and do not provide model-independent information about the spatial distribution of geo-neutrino sources within the Earth. Here in this paper we present a method for measuring previously unresolved components of Earth’s radiogenic heatingmore » using neutrino-electron elastic scattering and low-background, direction-sensitive tracking detectors.We calculate the exposures needed to probe various contributions to the total geo-neutrino flux, specifically those associated to potassium, the mantle and the core. The measurements proposed here chart a course for pioneering exploration of the veiled inner workings of the Earth.« less

Exploring the hidden interior of the Earth with directional neutrino measurements

PubMed Central

Leyton, Michael; Dye, Stephen; Monroe, Jocelyn

2017-01-01

Roughly 40% of the Earth’s total heat flow is powered by radioactive decays in the crust and mantle. Geo-neutrinos produced by these decays provide important clues about the origin, formation and thermal evolution of our planet, as well as the composition of its interior. Previous measurements of geo-neutrinos have all relied on the detection of inverse beta decay reactions, which are insensitive to the contribution from potassium and do not provide model-independent information about the spatial distribution of geo-neutrino sources within the Earth. Here we present a method for measuring previously unresolved components of Earth’s radiogenic heating using neutrino-electron elastic scattering and low-background, direction-sensitive tracking detectors. We calculate the exposures needed to probe various contributions to the total geo-neutrino flux, specifically those associated to potassium, the mantle and the core. The measurements proposed here chart a course for pioneering exploration of the veiled inner workings of the Earth. PMID:28691700

"Soft"or "hard" ionisation? Investigation of metastable gas temperature effect on direct analysis in real-time analysis of Voriconazole.

PubMed

Lapthorn, Cris; Pullen, Frank

2009-01-01

The performance of the direct analysis in real-time (DART) technique was evaluated across a range of metastable gas temperatures for a pharmaceutical compound, Voriconazole, in order to investigate the effect of metastable gas temperature on molecular ion intensity and fragmentation. The DART source has been used to analyse a range of analytes and from a range of matrices including drugs in solid tablet form and preparations, active ingredients in ointment, naturally occurring plant alkaloids, flavours and fragrances, from thin layer chromatography (TLC) plates, melting point tubes and biological matrices including hair, urine and blood. The advantages of this technique include rapid analysis time (as little as 5 s), a reduction in sample preparation requirements, elimination of mobile phase requirement and analysis of samples not typically amenable to atmospheric pressure ionisation (API) techniques. This technology has therefore been proposed as an everyday tool for identification of components in crude organic reaction mixtures.

Development and application of bond cleavage reactions in bioorthogonal chemistry.

PubMed

Li, Jie; Chen, Peng R

2016-03-01

Bioorthogonal chemical reactions are a thriving area of chemical research in recent years as an unprecedented technique to dissect native biological processes through chemistry-enabled strategies. However, current concepts of bioorthogonal chemistry have largely centered on 'bond formation' reactions between two mutually reactive bioorthogonal handles. Recently, in a reverse strategy, a collection of 'bond cleavage' reactions has emerged with excellent biocompatibility. These reactions have expanded our bioorthogonal chemistry repertoire, enabling an array of exciting new biological applications that range from the chemically controlled spatial and temporal activation of intracellular proteins and small-molecule drugs to the direct manipulation of intact cells under physiological conditions. Here we highlight the development and applications of these bioorthogonal cleavage reactions. Furthermore, we lay out challenges and propose future directions along this appealing avenue of research.

The kinetics of dissolution of dolomite in CO2-H2O systems at 1.5 to 65oC and 0 to 1 atm PCO2.

USGS Publications Warehouse

Busenberg, E.; Plummer, Niel

1982-01-01

Weight loss measurements at different T and PCO2 during experimental investigations of the dissolution kinetics of eight samples of dolomite permitted recognition of a two-stage process. During the first stage, which is brief, the surface composition of the dolomite becomes enriched with the MgCO3 component and the CaCO3 component dissolves faster. In the second and more important stage both components of the solid are released stoichiometrically, described quantitatively by three parallel consecutive forward reactions and one significant backward reaction. Dissolution rates are apparently more dependent on crystallographic order than on compositional variations. -M.S.

Engineering Transition-Metal-Coated Tungsten Carbides for Efficient and Selective Electrochemical Reduction of CO2 to Methane.

PubMed

Wannakao, Sippakorn; Artrith, Nongnuch; Limtrakul, Jumras; Kolpak, Alexie M

2015-08-24

The design of catalysts for CO2 reduction is challenging because of the fundamental relationships between the binding energies of the reaction intermediates. Metal carbides have shown promise for transcending these relationships and enabling low-cost alternatives. Herein, we show that directional bonding arising from the mixed covalent/metallic character plays a critical role in governing the surface chemistry. This behavior can be described by consideration of individual d-band components. We use this model to predict efficient catalysts based on tungsten carbide with a sub-monolayer of iron adatoms. Our approach can be used to predict site-preference and binding-energy trends for complex catalyst surfaces. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ozonides and epoxides from ozonization of pyrethroids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruzo, L.O.; Kimmel, E.C.; Casida, J.E.

Ozonization of pyrethroids as solutions or thin films yields products proposed to be epoxides from the 2,2-dihalovinyl substituents of deltamethrin and permethrin and transitory ozonides from these compounds and more stable ozonides from the 2-methyl-1-propenyl and 2-chloro-3,3,3-trifluoropropenyl substituents of phenothrin and descyanocyhalothrin, respectively. The unstable epoxydeltamethrin from ozonization is identified by /sup 1/H nuclear magnetic resonance spectroscopy and chemical ionization-mass spectroscopy and by reversion to deltamethrin on treatment of reaction mixtures with triphenylphosphine. Degradation of the ozonides yields the corresponding caronaldehyde in each case and trifluoroacetyl chloride from the chlorotrifluoropropenyl analogues. The ozonolysis mixtures are direct acting but weak bacterialmore » mutagens presumable due to their epoxide and ozonide components.« less

Hierarchical graphs for better annotations of rule-based models of biochemical systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Bin; Hlavacek, William

2009-01-01

In the graph-based formalism of the BioNetGen language (BNGL), graphs are used to represent molecules, with a colored vertex representing a component of a molecule, a vertex label representing the internal state of a component, and an edge representing a bond between components. Components of a molecule share the same color. Furthermore, graph-rewriting rules are used to represent molecular interactions, with a rule that specifies addition (removal) of an edge representing a class of association (dissociation) reactions and with a rule that specifies a change of vertex label representing a class of reactions that affect the internal state of amore » molecular component. A set of rules comprises a mathematical/computational model that can be used to determine, through various means, the system-level dynamics of molecular interactions in a biochemical system. Here, for purposes of model annotation, we propose an extension of BNGL that involves the use of hierarchical graphs to represent (1) relationships among components and subcomponents of molecules and (2) relationships among classes of reactions defined by rules. We illustrate how hierarchical graphs can be used to naturally document the structural organization of the functional components and subcomponents of two proteins: the protein tyrosine kinase Lck and the T cell receptor (TCR)/CD3 complex. Likewise, we illustrate how hierarchical graphs can be used to document the similarity of two related rules for kinase-catalyzed phosphorylation of a protein substrate. We also demonstrate how a hierarchical graph representing a protein can be encoded in an XML-based format.« less

A DIRECT ROUTE TO ACYLHYDROQUINONES FROM ALPHA-KETO ACIDS AND ALPHA-CARBOXAMIDO ACIDS. (R825330)

EPA Science Inventory

Abstract

The reaction of quinones with in situ generated acyl- or carboxamido radicals provides a direct route to the synthesis of acylhydroquinones not accessible by the photochemical reaction of quinones with aldehydes.

Improved Limit on Direct α Decay of the Hoyle State

NASA Astrophysics Data System (ADS)

Kirsebom, O. S.; Alcorta, M.; Borge, M. J. G.; Cubero, M.; Diget, C. Aa.; Fraile, L. M.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Jonson, B.; Madurga, M.; Nilsson, T.; Nyman, G.; Riisager, K.; Tengblad, O.; Turrión, M.

2012-05-01

The current evaluation of the triple-α reaction rate assumes that the α decay of the 7.65 MeV, 0+ state in C12, commonly known as the Hoyle state, proceeds sequentially via the ground state of Be8. This assumption is challenged by the recent identification of two direct α-decay branches with a combined branching ratio of 17(5)%. If correct, this would imply a corresponding reduction in the triple-α reaction rate with important astrophysical consequences. We have used the B11(He3,d) reaction to populate the Hoyle state and measured the decay to three α particles in complete kinematics. We find no evidence for direct α-decay branches, and hence our data do not support a revision of the triple-α reaction rate. We obtain an upper limit of 5×10-3 on the direct α decay of the Hoyle state at 95% C.L., which is 1 order of magnitude better than a previous upper limit.

Enhanced DNA Sensing via Catalytic Aggregation of Gold Nanoparticles

PubMed Central

Huttanus, Herbert M.; Graugnard, Elton; Yurke, Bernard; Knowlton, William B.; Kuang, Wan; Hughes, William L.; Lee, Jeunghoon

2014-01-01

A catalytic colorimetric detection scheme that incorporates a DNA-based hybridization chain reaction into gold nanoparticles was designed and tested. While direct aggregation forms an inter-particle linkage from only ones target DNA strand, the catalytic aggregation forms multiple linkages from a single target DNA strand. Gold nanoparticles were functionalized with thiol-modified DNA strands capable of undergoing hybridization chain reactions. The changes in their absorption spectra were measured at different times and target concentrations and compared against direct aggregation. Catalytic aggregation showed a multifold increase in sensitivity at low target concentrations when compared to direct aggregation. Gel electrophoresis was performed to compare DNA hybridization reactions in catalytic and direct aggregation schemes, and the product formation was confirmed in the catalytic aggregation scheme at low levels of target concentrations. The catalytic aggregation scheme also showed high target specificity. This application of a DNA reaction network to gold nanoparticle-based colorimetric detection enables highly-sensitive, field-deployable, colorimetric readout systems capable of detecting a variety of biomolecules. PMID:23891867

Method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide

DOEpatents

Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.

2000-01-01

A method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide within a reformer 10 is disclosed. According to the method, a stream including an oxygen-containing gas is directed adjacent to a first vessel 18 and the oxygen-containing gas is heated. A stream including unburned fuel is introduced into the oxygen-containing gas stream to form a mixture including oxygen-containing gas and fuel. The mixture of oxygen-containing gas and unburned fuel is directed tangentially into a partial oxidation reaction zone 24 within the first vessel 18. The mixture of oxygen-containing gas and fuel is further directed through the partial oxidation reaction zone 24 to produce a heated reformate stream including hydrogen gas and carbon monoxide. Steam may also be mixed with the oxygen-containing gas and fuel, and the reformate stream from the partial oxidation reaction zone 24 directed into a steam reforming zone 26. High- and low-temperature shift reaction zones 64,76 may be employed for further fuel processing.

Current progress in asymmetric Biginelli reaction: an update.

PubMed

Heravi, Majid M; Moradi, Razieh; Mohammadkhani, Leyla; Moradi, Borzou

2018-06-23

The Biginelli reaction, involving a three-component reaction of an aromatic aldehyde, urea and ethyl acetoacetate, has emerged as an extremely useful synthetic tool to organic chemists for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones and related heterocyclic compounds. In the past decades, the asymmetric variants of this reaction have been at the forefront of investigations in several research groups. In 2013, we highlighted the developments occurred in the asymmetric version of the Biginelli reaction. This review article focuses on the recent developments of asymmetric Biginelli reaction covers the literature going back to 2012.

Mechanistic insights into iron catalyzed dehydrogenation of formic acid: β-hydride elimination vs. direct hydride transfer.

PubMed

Yang, Xinzheng

2013-09-07

Density functional theory calculations reveal a complete reaction mechanism with detailed energy profiles and transition state structures for the dehydrogenation of formic acid catalyzed by an iron complex, [P(CH2CH2PPh2)3FeH](+). In the cationic reaction pathway, a β-hydride elimination process is confirmed to be the rate-determining step in this catalytic reaction. A potential reaction pathway starting with a direct hydride transfer from HCOO(-) to Fe is found to be possible, but slightly less favorable than the catalytic cycle with a β-hydride elimination step.

Iron-catalyzed stereospecific activation of olefinic C-H bonds with Grignard reagent for synthesis of substituted olefins.

PubMed

Ilies, Laurean; Asako, Sobi; Nakamura, Eiichi

2011-05-25

The reaction of an aryl Grignard reagent with a cyclic or acyclic olefin possessing a directing group such as pyridine or imine results in the stereospecific substitution of the olefinic C-H bond syn to the directing group. The reaction takes place smoothly and without isomerization of the product olefin in the presence of a mild oxidant (1,2-dichloro-2-methylpropane) and an aromatic cosolvent. Several lines of evidence suggest that the reaction proceeds via iron-catalyzed olefinic C-H bond activation rather than an oxidative Mizoroki-Heck-type reaction.

Characterization of clinical photosensitivity in cutaneous lupus erythematosus.

PubMed

Foering, Kristen; Chang, Aileen Y; Piette, Evan W; Cucchiara, Andrew; Okawa, Joyce; Werth, Victoria P

2013-08-01

Photosensitivity (PS) in lupus erythematosus (LE) is frequently determined by patient report. We sought to characterize self-reported PS in cutaneous LE (CLE). The PS survey was used to classify subject responses into 5 phenotypes: direct sun-induced CLE flare (directCLE); general exacerbation of CLE (genCLE); polymorphic light eruption-like reactions (genSkin); general pruritus/paresthesias (genRxn); and sun-induced systemic symptoms (genSys). In all, 91 subjects with CLE alone or with CLE and systemic LE were interviewed. In all, 81% ascribed to 1 or more PS phenotypes. CLE-specific reactions (direct sun-induced CLE flare or general exacerbation of CLE) were reported by 86% of photosensitive subjects. Higher CLE disease activity (measured by CLE Disease Area and Severity Index activity scores) was suggestive of direct sun-induced CLE flare reactions (P = .09). In all, 60% of photosensitive subjects described CLE-nonspecific reactions: polymorphic light eruption-like rash and general pruritus/paresthesias. These phenotypes often co-occurred with CLE-specific reactions and were predicted by more systemic disease activity as measured by Physicians Global Assessment (PGA) scores in regression analyses (genSkin, P = .02) and (genRxn, P = .05). In all, 36% of subjects reported systemic reactions and higher PGA scores were predictive of the sun-induced systemic symptoms phenotype (P = .02); a diagnosis of systemic LE was not (P = .14). PS was inferred from patient report and not directly observed. Characterization of self-reported PS in LE reveals that patients experience combinations of CLE-specific, CLE-nonspecific, and systemic reactions to sunlight. Sun-induced CLE flares are associated with more active CLE disease. Polymorphic light eruption-like, generalized pruritus/paresthesias, and systemic reactions are associated with more active systemic disease. Recognition of PS phenotypes will permit improved definitions of clinical PS and allow for more precise investigation into its pathophysiology. Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

21 CFR 184.1311 - Ferrous lactate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... prepared by reacting calcium lactate or sodium lactate with ferrous sulfate, direct reaction of lactic acid with iron filings, reaction of ferrous chloride with sodium lactate, or reaction of ferrous sulfate...

Spatially-Interactive Biomolecular Networks Organized by Nucleic Acid Nanostructures

PubMed Central

Fu, Jinglin; Liu, Minghui; Liu, Yan; Yan, Hao

2013-01-01

Conspectus Living systems have evolved a variety of nanostructures to control the molecular interactions that mediate many functions including the recognition of targets by receptors, the binding of enzymes to substrates, and the regulation of enzymatic activity. Mimicking these structures outside of the cell requires methods that offer nanoscale control over the organization of individual network components. Advances in DNA nanotechnology have enabled the design and fabrication of sophisticated one-, two- and three-dimensional (1D, 2D and 3D) nanostructures that utilize spontaneous and sequence specific DNA hybridization. Compared to other self-assembling biopolymers, DNA nanostructures offer predictable and programmable interactions, and surface features to which other nanoparticles and bio-molecules can be precisely positioned. The ability to control the spatial arrangement of the components while constructing highly-organized networks will lead to various applications of these systems. For example, DNA nanoarrays with surface displays of molecular probes can sense noncovalent hybridization interactions with DNA, RNA, and proteins and covalent chemical reactions. DNA nanostructures can also align external molecules into well-defined arrays, which may improve the resolution of many structural determination methods, such as X-ray diffraction, cryo-EM, NMR, and super-resolution fluorescence. Moreover, by constraining target entities to specific conformations, self-assembled DNA nanostructures can serve as molecular rulers to evaluate conformation-dependent activities. This Account describes the most recent advances in the DNA nanostructure directed assembly of biomolecular networks and explores the possibility of applying this technology to other fields of study. Recently, several reports have demonstrated the DNA nanostructure directed assembly of spatially-interactive biomolecular networks. For example, researchers have constructed synthetic multi-enzyme cascades by organizing the position of the components using DNA nanoscaffolds in vitro, or by utilizing RNA matrices in vivo. These structures display enhanced efficiency compared to the corresponding unstructured enzyme mixtures. Such systems are designed to mimic cellular function, where substrate diffusion between enzymes is facilitated and reactions are catalyzed with high efficiency and specificity. In addition, researchers have assembled multiple choromophores into arrays using a DNA nanoscaffold that optimizes the relative distance between the dyes and their spatial organization. The resulting artificial light harvesting system exhibits efficient cascading energy transfers. Finally, DNA nanostructures have been used as assembly templates to construct nanodevices that execute rationally-designed behaviors, including cargo loading, transportation and route control. PMID:22642503

Components of polarization-transfer to a bound proton in a deuteron measured by quasi-elastic electron scattering

NASA Astrophysics Data System (ADS)

Izraeli, D.; Yaron, I.; Schlimme, B. S.; Achenbach, P.; Arenhövel, H.; Ashkenazi, A.; Beričič, J.; Böhm, R.; Bosnar, D.; Cohen, E. O.; Distler, M. O.; Esser, A.; Friščić, I.; Gilman, R.; Korover, I.; Lichtenstadt, J.; Mardor, I.; Merkel, H.; Middleton, D. G.; Mihovilovič, M.; Müller, U.; Olivenboim, M.; Piasetzky, E.; Pochodzalla, J.; Ron, G.; Schoth, M.; Schulz, F.; Sfienti, C.; Širca, S.; Štajner, S.; Strauch, S.; Thiel, M.; Tyukin, A.; Weber, A.; A1 Collaboration

2018-06-01

We report the first measurements of the transverse (Px and Py) and longitudinal (Pz) components of the polarization transfer to a bound proton in the deuteron via the 2H (e → ,e‧ p →) reaction, over a wide range of missing momentum. A precise determination of the electron beam polarization reduces the systematic uncertainties on the individual components to a level that enables a detailed comparison to a state-of-the-art calculation of the deuteron using free-proton electromagnetic form factors. We observe very good agreement between the measured and the calculated Px /Pz ratios, but deviations of the individual components. Our results cannot be explained by medium modified electromagnetic form factors. They point to an incomplete description of the nuclear reaction mechanism in the calculation.

Providing ABO-identical platelets and cryoprecipitate to (almost) all patients: approach, logistics, and associated decreases in transfusion reaction and red blood cell alloimmunization incidence.

PubMed

Henrichs, Kelly F; Howk, Nedda; Masel, Debra S; Thayer, Mark; Refaai, Majed A; Kirkley, Scott A; Heal, Joanna M; Blumberg, Neil

2012-03-01

There are multiple benefits to transfusing only ABO-identical blood components. Historically our institution routinely transfused ABO-nonidentical platelets (PLTs) and cryoprecipitate to surgical patients. In April 2005, we implemented a policy of transfusing only ABO-identical components whenever feasible, regardless of outdating or logistic considerations. Technical staff closely monitored product usage and adjusted blood center orders based on recent utilization and planned transfusions. When unable to provide ABO-identical PLTs, ABO-compatible PLTs were washed to remove incompatible plasma. Data on outdating were collected for 18 months before and after implementation. We compared transfusion reaction and red blood cell (RBC) alloimmunization incidence for 4 years preceding (2001-2004) and subsequent (2006-2009) to implementation. In the year after implementation, only 11 of 410 surgical patients received ABO-nonidentical PLTs (2.7%). There was a 5.6% increase in outdating of PLTs. Transfusing ABO-identical components was associated with significant reductions in febrile (-46%; 8.0 to 4.3 per 10,000 components; p < 0.0001) and allergic transfusion reactions (-23%; from 7.0 to 5.4 per 10,000 components; p = 0.025). A progressive reduction in de novo RBC alloimmunization incidence also occurred (-50% by 2009; p = 0.03). Providing ABO-identical PLTs to almost all patients was feasible in our setting by changing ordering and inventorying procedures and making the ABO-identical policy a staff priority. Unexpected and striking reductions in febrile and allergic reactions and RBC alloimmunization were observed, of uncertain causal relationship to this ABO policy change, which will require further study. © 2011 American Association of Blood Banks.

Excipients in topical corticosteroid preparations in Canada.

PubMed Central

Searles, G E; DesGroseilliers, J P

1989-01-01

Topical corticosteroids are widely used for the treatment of dermatoses in Canada. The effects of the various nontherapeutic components of these formulations are less well known than those of the active ingredients and may cause adverse reactions. Information on the components is fragmentary and is scattered throughout the literature. We have attempted to consolidate this information into one source. Recent provincial legislation requiring the generic substitution of interchangeable products and the nondisclosure of all ingredients in product labelling hinder the search for an excipient that has caused an adverse reaction. Practitioner participation in the Cutaneous Adverse Reaction Registry of the Canadian Dermatology Association will identify sensitizing excipients and will support efforts by the profession to obtain more effective and safer products. PMID:2766179

Greater Severity of Peanut Challenge Reactions Using a High fat versus Low Fat Matrix Vehicle.

PubMed

Pettersson, M Eleonore; Koppelman, Gerard H; Schins, Afke M M; van Ginkel, C Doriene; Flokstra-de Blok, Bertine M J; Kollen, Boudewijn J; Dubois, Anthony E J

2018-06-16

Food allergy is a potentially life-threatening disease with a detrimental effect on the quality of life of caregivers and children.(1) Although many different types of food have been identified as potential elicitors of allergic reactions, only a small number of these foods cause the majority of reactions.(2) Food consists of a complex mixture of nutrient and non-nutrient components and their molecular interactions, which are known as the food matrix. Individual matrix components, or the matrix as a whole, may interact with a food allergen and may influence the clinical response to that allergen. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Isolation of tert-alkylphenols from the products of alkylation of phenols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nesterova, T.N.; Verevkin, S.P.; Rempel', R.D.

1987-08-10

The authors studied the conditions of isolation of tert-amyl-, hexyl-, heptyl-, octyl-, decyl-, and dodecylphenols, and tert-alkylcresols, alkylpyrocatechols, and alkylhydroquinones from alkylation products. The compounds were isolated in all cases from reaction mixtures obtained in presence of cation-exchange resins of the KU-2 type. A preliminary stage, flash evaporation of the reaction mass at 4-13 Pa for 5-15 min, is needed to prevent decomposition of tert-alkylphenols during their isolation from acid reaction mixtures by fractionation. Flash distillation of high-boiling tert-alkylphenols should be conducted in presence of a component lowering the boiling point of the mixture, added in 1:(0.5-1.0) weight ratio ofmore » original mixture to the component.« less

An Experiment to Illustrate the Hazards of Exothermic Reaction Scale-Up

ERIC Educational Resources Information Center

Clark, William; Lei, Melinda; Kirichenko, Erika; Dickerson, Kellie; Prytko, Robert

2017-01-01

Exothermic reactions can present safety hazards and there is a recognized need for reaction safety education at the undergraduate level. We present an experiment that illustrates the pitfall of direct scale-up of an exothermic reaction that can lead to thermal runaway. The iodide-catalyzed hydrogen peroxide decomposition reaction yields…

Attempted nonenzymatic template-directed oligomerizations on a polyadenylic acid template: implications for the nature of the first genetic material

NASA Technical Reports Server (NTRS)

Stribling, R.; Miller, S. L.

1991-01-01

Previous attempts to produce nonenzymatic template-directed oligomerizations of activated pyrimidines on polypurine templates have been unsuccessful. The only efficient reactions are those where the template is composed primarily of pyrimidines, especially cytosine. Because molecular evolution requires that a synthesized daughter polynucleotide be capable of acting as a template for the synthesis of the original polynucleotide, the one-way replication achieved thus far is inadequate to initiate an evolving system. Several uracil analogs were used in this investigation in order to search for possible replacements for uracil. The monomers used in this investigation were the imidazolides of UMP, xanthosine 5'-monophosphate, the bis-monophosphates of the acyclic nucleosides of uracil, and 2,4-quinazolinedione. The concentrations of various salts, buffers, pH, and temperature were among the different variables investigated in attempts to find conditions that would permit template-directed oligomerizations. Although the different monomers in this study demonstrated varying abilities to form very short oligomers, we were unable to detect any enhancement of this oligomerization that could be attributed to the poly(A) template. Although special conditions might be found that would allow purine-rich templates to work, these reactions cannot be considered robust. The results of our experiments suggest that pyrimidines were not part of the original replicating system on the primitive Earth. It has already been shown that ribose is an unlikely component of the first replicating systems, and we now suggest that phosphate was absent as well. This is due to the low solubility of phosphate in the present ocean (3 x 10(-6) M), as well as the difficulty of prebiotic activation of phosphates.

Direct amidation of carboxylic acids catalyzed by ortho-iodo arylboronic acids: catalyst optimization, scope, and preliminary mechanistic study supporting a peculiar halogen acceleration effect.

PubMed

Gernigon, Nicolas; Al-Zoubi, Raed M; Hall, Dennis G

2012-10-05

The importance of amides as a component of biomolecules and synthetic products motivates the development of catalytic, direct amidation methods employing free carboxylic acids and amines that circumvent the need for stoichiometric activation or coupling reagents. ortho-Iodophenylboronic acid 4a has recently been shown to catalyze direct amidation reactions at room temperature in the presence of 4A molecular sieves as dehydrating agent. Herein, the arene core of ortho-iodoarylboronic acid catalysts has been optimized with regards to the electronic effects of ring substitution. Contrary to the expectation, it was found that electron-donating substituents are preferable, in particular, an alkoxy substituent positioned para to the iodide. The optimal new catalyst, 5-methoxy-2-iodophenylboronic acid (MIBA, 4f), was demonstrated to be kinetically more active than the parent des-methoxy catalyst 4a, providing higher yields of amide products in shorter reaction times under mild conditions at ambient temperature. Catalyst 4f is recyclable and promotes the formation of amides from aliphatic carboxylic acids and amines, and from heteroaromatic carboxylic acids and other functionalized substrates containing moieties like a free phenol, indole and pyridine. Mechanistic studies demonstrated the essential role of molecular sieves in this complex amidation process. The effect of substrate stoichiometry, concentration, and measurement of the catalyst order led to a possible catalytic cycle based on the presumed formation of an acylborate intermediate. The need for an electronically enriched ortho-iodo substituent in catalyst 4f supports a recent theoretical study (Marcelli, T. Angew. Chem. Int. Ed.2010, 49, 6840-6843) with a purported role for the iodide as a hydrogen-bond acceptor in the orthoaminal transition state.

Chemical Characterization and Reactivity of Fuel-Oxidizer Reaction Product

NASA Technical Reports Server (NTRS)

David, Dennis D.; Dee, Louis A.; Beeson, Harold D.

1997-01-01

Fuel-oxidizer reaction product (FORP), the product of incomplete reaction of monomethylhydrazine and nitrogen tetroxide propellants prepared under laboratory conditions and from firings of Shuttle Reaction Control System thrusters, has been characterized by chemical and thermal analysis. The composition of FORP is variable but falls within a limited range of compositions that depend on three factors: the fuel-oxidizer ratio at the time of formation; whether the composition of the post-formation atmosphere is reducing or oxidizing; and the reaction or post-reaction temperature. A typical composition contains methylhydrazinium nitrate, ammonium nitrate, methylammonium nitrate, and trace amounts of hydrazinium nitrate and 1,1-dimethylhydrazinium nitrate. Thermal decomposition reactions of the FORP compositions used in this study were unremarkable. Neither the various compositions of FORP, the pure major components of FORP, nor mixtures of FORP with propellant system corrosion products showed any unusual thermal activity when decomposed under laboratory conditions. Off-limit thruster operations were simulated by rapid mixing of liquid monomethylhydrazine and liquid nitrogen tetroxide in a confined space. These tests demonstrated that monomethylhydrazine, methylhydrazinium nitrate, ammonium nitrate, or Inconel corrosion products can induce a mixture of monomethylhydrazine and nitrogen tetroxide to produce component-damaging energies. Damaging events required FORP or metal salts to be present at the initial mixing of monomethylhydrazine and nitrogen tetroxide.

A study of cross-reactions between mango contact allergens and urushiol.

PubMed

Oka, Keiko; Saito, Fumio; Yasuhara, Tadashi; Sugimoto, Akiko

2004-01-01

The allergens causing mango dermatitis have long been suspected to be alk(en)yl catechols and/or alk(en)yl resorcinols on the basis of observed cross-sensitivity reactions to mango in patients known to be sensitive to poison ivy and oak (Toxicodendron spp.). Earlier, we reported the 3 resorcinol derivatives: heptadecadienylresorcinol (I), heptadecenylresorcinol (II) and pentadecylresorcinol (III); collectively named 'mangol', as mango allergens. In this study, we extracted the 1st 2 components (I and II) from the Philippine mango, adjusted them to 0.05% concentration in petrolatum and patch tested the components on 2 subjects with mango dermatitis. Both subjects reacted to I. 1 subject also elicited a weaker positive reaction to II. To investigate the cross-reaction between mangol and urushiol, we also patch tested the same subjects with urushiol. The subject sensitive to II reacted to urushiol. 6 subjects with a history of lacquer contact dermatitis and positive reactions to urushiol were similarly patch tested. 5 persons reacted to I. 2 subjects also exhibited a slower but positive reaction to II. This is the 1st report in which heptadec(adi)enyl resorcinols known to be present in mango have been shown to elicit positive patch test reactions in mango-sensitive patients.

21 CFR 184.1311 - Ferrous lactate.

Code of Federal Regulations, 2011 CFR

2011-04-01

.... It is prepared by reacting calcium lactate or sodium lactate with ferrous sulfate, direct reaction of lactic acid with iron filings, reaction of ferrous chloride with sodium lactate, or reaction of ferrous...

A Successful Replacement of Phenols with Isocyanides in the Bargellini Reaction: Synthesis of 3-Carboxamido-Isobutyric Acids.

PubMed

Giustiniano, Mariateresa; Pelliccia, Sveva; Galli, Ubaldina; Amato, Jussara; Travagin, Fabio; Novellino, Ettore; Tron, Gian Cesare

2016-11-18

Old multicomponent reactions are still a source of inspiration for discovering novel combinations of three or more reactants. A simple idea is to replace one of the educts of a known multicomponent reaction with another functional group and still be able to mimic the same reactivity. Following this line of thought, we report a three-component reaction in which isocyanides are able to open the epoxide intermediate of the Bargellini reaction affording 3-carboxamido-isobutyric acids in yields of 47-95%.

Formation of a1 Ions Directly from Oxazolone b2 Ions: an Energy-Resolved and Computational Study

NASA Astrophysics Data System (ADS)

Bythell, Benjamin J.; Harrison, Alex G.

2015-05-01

It is well-known that oxazolone b2 ions fragment extensively by elimination of CO to form a2 ions, which often fragment further to form a1 ions. Less well-known is that some oxazolone b2 ions may fragment directly to form a1 ions. The present study uses energy-resolved collision-induced dissociation experiments to explore the occurrence of the direct b2→a1 fragmentation reaction. The experimental results show that the direct b2→a1 reaction is generally observed when Gly is the C-terminal residue of the oxazolone. When the C-terminal residue is more complex, it is able to provide increased stability of the a2 product in the b2→a2 fragmentation pathway. Our computational studies of the relative critical reaction energies for the b2→a2 reaction compared with those for the b2→a1 reaction provide support that the critical reaction energies are similar for the two pathways when the C-terminal residue of the oxazolone is Gly. By contrast, when the nitrogen of the oxazolone ring in the b2 ion does not bear a hydrogen, as in the Ala-Sar and Tyr-Sar (Sar = N-methylglycine) oxazolone b2 ions, a1 ions are not formed but rather neutral imine elimination from the N-terminus of the b2 ion becomes a dominant fragmentation reaction. The M06-2X/6-31+G(d,p) density functional theory calculations are in general agreement with the experimental data for both types of reaction. In contrast, the B3LYP/6-31+G(d,p) model systematically underestimates the barriers of these SN2-like b2→a1 reaction. The difference between the two methods of barrier calculation are highly significant ( P < 0.001) for the b2→a1 reaction, but only marginally significant ( P = 0.05) for the b2→a2 reaction. The computations provide further evidence of the limitations of the B3LYP functional when describing SN2-like reactions.

How does a collision warning system shape driver's brake response time? The influence of expectancy and automation complacency on real-life emergency braking.

PubMed

Ruscio, Daniele; Ciceri, Maria Rita; Biassoni, Federica

2015-04-01

Brake Reaction Time (BRT) is an important parameter for road safety. Previous research has shown that drivers' expectations can impact RT when facing hazardous situations, but driving with advanced driver assistance systems, can change the way BRT are considered. The interaction with a collision warning system can help faster more efficient responses, but at the same time can require a monitoring task and evaluation process that may lead to automation complacency. The aims of the present study are to test in a real-life setting whether automation compliancy can be generated by a collision warning system and what component of expectancy can impact the different tasks involved in an assisted BRT process. More specifically four component of expectancy were investigated: presence/absence of anticipatory information, previous direct experience, reliability of the device, and predictability of the hazard determined by repeated use of the warning system. Results supply indication on perception time and mental elaboration of the collision warning system alerts. In particular reliable warning quickened the decision making process, misleading warnings generated automation complacency slowing visual search for hazard detection, lack of directed experienced slowed the overall response while unexpected failure of the device lead to inattentional blindness and potential pseudo-accidents with surprise obstacle intrusion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Monitoring radionuclide contamination in the unsaturated zone - Lessons learned at the Amargosa Desert Research Site, Nye County, Nevada

USGS Publications Warehouse

Stonestrom, David A.; Abraham, Jared D.; Andraski, Brian J.; Baker, Ronald J.; Mayers, C. Justin; Michel, Robert L.; Prudic, David E.; Striegl, Robert G.; Walvoord, Michelle Ann

2004-01-01

Contaminant-transport processes are being investigated at the U.S. Geological Survey’s Amargosa Desert Research Site (A DRS), adjacent to the Nation’s first commercial disposal facility for low-level radioactive waste. Gases containing tritium and radiocarbon are migrating through a 110-m thick unsaturated zone from unlined trenches that received waste from 1962 to 1992. Results relevant to long- term monitoring of radionuclides are summarized as follows. Contaminant plumes have unexpected histories and spatial configurations due to uncertainties in the: (1) geologic framework, (2) biochemical reactions involving waste components, (3) interactions between plume components and unsaturated-zone materials, (4) disposal practices, and (5) physical transport processes. Information on plume dynamics depends on ex-situ wet-chemical techniques because in-situ sensors for the radionuclides of interest do not exist. As at other radioactive-waste disposal facilities, radionuclides at the ADRS are mixed with varying amounts of volatile organic compounds (VOCs). Carbon-dioxide and VOC anomalies provide proxies for radioactive contamination. Contaminants in the unsaturated zone migrate along preferential pathways. Effective monitoring thus requires accurate geologic characterization. Direct- current electrical-resistivity imaging successfully mapped geologic units controlling preferential transport at the ADRS. Direct sampling of water from the unsaturated zone is complex and time consuming. Sampling plant water is an efficient alternative for mapping shallow tritium contamination.

New insights into atmospherically relevant reaction systems using direct analysis in real-time mass spectrometry (DART-MS)

NASA Astrophysics Data System (ADS)

Zhao, Yue; Fairhurst, Michelle C.; Wingen, Lisa M.; Perraud, Véronique; Ezell, Michael J.; Finlayson-Pitts, Barbara J.

2017-04-01

The application of direct analysis in real-time mass spectrometry (DART-MS), which is finding increasing use in atmospheric chemistry, to two different laboratory model systems for airborne particles is investigated: (1) submicron C3-C7 dicarboxylic acid (diacid) particles reacted with gas-phase trimethylamine (TMA) or butylamine (BA) and (2) secondary organic aerosol (SOA) particles from the ozonolysis of α-cedrene. The diacid particles exhibit a clear odd-even pattern in their chemical reactivity toward TMA and BA, with the odd-carbon diacid particles being substantially more reactive than even ones. The ratio of base to diacid in reacted particles, determined using known diacid-base mixtures, was compared to that measured by high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS), which vaporizes the whole particle. Results show that DART-MS probes ˜ 30 nm of the surface layer, consistent with other studies on different systems. For α-cedrene SOA particles, it is shown that varying the temperature of the particle stream as it enters the DART-MS ionization region can distinguish between specific components with the same molecular mass but different vapor pressures. These results demonstrate the utility of DART-MS for (1) examining reactivity of heterogeneous model systems for atmospheric particles and (2) probing components of SOA particles based on volatility.

Design study for a magnetically supported reaction wheel

NASA Technical Reports Server (NTRS)

Stocking, G.; Dendy, J.; Sabnis, A.

1974-01-01

Results are described of a study program in which the characteristics of a magnetically supported reaction wheel are defined. Tradeoff analyses are presented for the principal components, which are then combined in several reaction wheel design concepts. A preliminary layout of the preferred configuration is presented along with calculated design and performance parameters. Recommendations are made for a prototype development program.

Multicomponent Macrocyclization Reactions (MCMRs) Employing Highly Reactive Acyl Ketene and Nitrile Oxide Intermediates

PubMed Central

Knapp, John M.; Fettinger, James C.; Kurth, Mark J.

2011-01-01

An efficient synthesis of spiro-fused macrolactams by a multicomponent macrocyclization reaction (MCMR) is reported. The use of highly reactive, transient intermediates in this MCMR permits short reaction times, even at high dilution. The methods employed for this MCMR were first developed as a four component strategy for the synthesis of β-ketoamide isoxazolines. PMID:21827181

A Method for Decomposition of the Basic Reaction of Biological Macromolecules into Exponential Components

NASA Astrophysics Data System (ADS)

Barabash, Yu. M.; Lyamets, A. K.

2016-12-01

The structural and dynamical properties of biological macromolecules under non-equilibrium conditions determine the kinetics of their basic reaction to external stimuli. This kinetics is multiexponential in nature. This is due to the operation of various subsystems in the structure of macromolecules, as well as the effect of the basic reaction on the structure of macromolecules. The situation can be interpreted as a manifestation of the stationary states of macromolecules, which are represented by monoexponential components of the basic reaction (Monod-Wyman-Changeux model) Monod et al. (J Mol Cell Biol 12:88-118, 1965). The representation of multiexponential kinetics of the basic reaction in the form of a sum of exponential functions (A(t)={sum}_{i=1}^n{a}_i{e}^{-{k}_it}) is a multidimensional optimization problem. To solve this problem, a gradient method of optimization with software determination of the amount of exponents and reasonable calculation time is developed. This method is used to analyze the kinetics of photoinduced electron transport in the reaction centers (RC) of purple bacteria and the fluorescence induction in the granum thylakoid membranes which share a common function of converting light energy.

An efficient synthesis of symmetric and unsymmetric bis-(β-aminoamides) via Ugi multicomponent reaction.

PubMed

La Spisa, Fabio; Feo, Alberto; Mossetti, Riccardo; Tron, Gian Cesare

2012-12-07

A library of symmetrical and unsymmetrical bis-(β-aminoamides) has been prepared starting from symmetrical secondary diamines by using a double Ugi four-component reaction. A sacrifical Mumm rearrangement, thanks to the use of 2-hydroxymethyl benzoic acid, is necessary to suppress the competing split-Ugi reaction, increasing the yield and simplifying the purification step. The scope, the reaction conditions, and the role of water in trapping the nitrilium intermediate are also discussed.

Direct Visualization of Catalytically Active Sites at the FeO–Pt(111) Interface

DOE PAGES

Kudernatsch, Wilhelmine; Peng, Guowen; Zeuthen, Helene; ...

2015-05-31

Within the area of surface science, one of the “holy grails” is to directly visualize a chemical reaction at the atomic scale. Whereas this goal has been reached by high-resolution scanning tunneling microscopy (STM) in a number of cases for reactions occurring at flat surfaces, such a direct view is often inhibited for reaction occurring at steps and interfaces. Here we have studied the CO oxidation reaction at the interface between ultrathin FeO islands and a Pt(111) support by in situ STM and density functional theory (DFT) calculations. Time-lapsed STM imaging on this inverse model catalyst in O 2 andmore » CO environments revealed catalytic activity occurring at the FeO–Pt(111) interface and directly showed that the Fe-edges host the catalytically most active sites for the CO oxidation reaction. This is an important result since previous evidence for the catalytic activity of the FeO–Pt(111) interface is essentially based on averaging techniques in conjunction with DFT calculations. As a result, the presented STM results are in accord with DFT+U calculations, in which we compare possible CO oxidation pathways on oxidized Fe-edges and O-edges. We found that the CO oxidation reaction is more favorable on the oxidized Fe-edges, both thermodynamically and kinetically.« less