WorldWideScience

Sample records for rapid exothermic reactions

  1. Rapid biocatalytic polytransesterification: reaction kinetics in an exothermic reaction

    Science.gov (United States)

    Chaudhary; Beckman; Russell

    1998-08-20

    Biocatalytic polytransesterification at high concentrations of monomers proceeds rapidly and is accompanied by an increase in the temperature of the reaction mixture due to liberation of heat of reaction during the initial phase. We have used principles of reaction calorimetry to monitor the kinetics of polymerization during this initial phase, thus relating the temperature to the extent of polymerization. Rate of polymerization increases with the concentration of monomers. This is also reflected by the increase in the temperature of the reaction mixture. Using time-temperature-conversion contours, a differential method of kinetic analysis was used to calculate the energy of activation ( approximately 15.1 Kcal/mol). Copyright 1998 John Wiley & Sons, Inc.

  2. The exothermic reaction route of a self-heatable conductive ink for rapid processable printed electronics.

    Science.gov (United States)

    Shin, Dong-Youn; Han, Jin Wook; Chun, Sangki

    2014-01-07

    We report the exothermic reaction route and new capability of a self-heatable conductive ink (Ag2O and silver 2,2-dimethyloctanoate) in order to achieve both a low sintering temperature and electrical resistivity within a short sintering time for flexible printed electronics and display appliances. Unlike conventional conductive ink, which requires a costly external heating instrument for rapid sintering, self-heatable conductive ink by itself is capable of generating heat as high as 312 °C when its exothermic reaction is triggered at a temperature of 180 °C. This intensive exothermic reaction is found to result from the recursive reaction of the 2,2-dimethyloctanoate anion, which is thermally dissociated from silver 2,2-dimethyloctanoate, with silver oxide microparticles. Through this recursive reaction, a massive number of silver atoms are supplied from silver oxide microparticles, and the nucleation of silver atoms and the fusion of silver nanoparticles become the major source of heat. This exothermic reaction eventually realizes the electrical resistivity of self-heatable conductive ink as low as 27.5 μΩ cm within just 40 s by combining chemical annealing, which makes it suitable for the roll-to-roll printable electronics such as a flexible touch screen panel.

  3. Reactor for exothermic reactions

    Science.gov (United States)

    Smith, Jr., Lawrence A.; Hearn, Dennis; Jones, Jr., Edward M.

    1993-01-01

    A liquid phase process for oligomerization of C.sub.4 and C.sub.5 isoolefins or the etherification thereof with C.sub.1 to C.sub.6 alcohols wherein the reactants are contacted in a reactor with a fixed bed acid cation exchange resin catalyst at an LHSV of 5 to 20, pressure of 0 to 400 psig and temperature of 120.degree. to 300.degree. F. Wherein the improvement is the operation of the reactor at a pressure to maintain the reaction mixture at its boiling point whereby at least a portion but less than all of the reaction mixture is vaporized. By operating at the boiling point and allowing a portion of the reaction mixture to vaporize, the exothermic heat of reaction is dissipated by the formation of more boil up and the temperature in the reactor is controlled.

  4. Method for conducting exothermic reactions

    Science.gov (United States)

    Smith, Jr., Lawrence; Hearn, Dennis; Jones, Jr., Edward M.

    1993-01-01

    A liquid phase process for oligomerization of C.sub.4 and C.sub.5 isoolefins or the etherification thereof with C.sub.1 to C.sub.6 alcohols wherein the reactants are contacted in a reactor with a fixed bed acid cation exchange resin catalyst at an LHSV of 5 to 20, pressure of 0 to 400 psig and temperature of 120.degree. to 300.degree. F. wherein the improvement is the operation of the reactor at a pressure to maintain the reaction mixture at its boiling point whereby at least a portion but less than all of the reaction mixture is vaporized. By operating at the boiling point and allowing a portion of the reaction mixture to vaporize, the exothermic heat of reaction is dissipated by the formation of more boil up and the temperature in the reactor is controlled.

  5. Density fingering of an exothermic autocatalytic reaction.

    Science.gov (United States)

    Bánsági, T; Horváth, D; Tóth, A; Yang, J; Kalliadasis, S; De Wit, A

    2003-11-01

    Density fingering of exothermic autocatalytic fronts in vertically oriented porous media and Hele-Shaw cells is studied theoretically for chemical reactions where the solutal and thermal contribution to density changes have opposite signs. The competition between these two effects leads to thermal plumes for ascending fronts. The descending fronts behave strikingly differently as they can feature, for some values of the parameters, fingers of constant amplitude and wavelength. The differences between up and down going fronts are discussed in terms of dispersion curves and nonlinear dynamics. The theoretically predicted dispersion curves are experimentally evidenced with the chlorite-tetrathionate reaction.

  6. The Issue of Calculating the Final Temperature of the Products of Rapid Exothermic Chemical Reactions with Significant Energy Release in a Closed Volume

    Science.gov (United States)

    Lazarev, V.; Geidmanis, D.

    2016-02-01

    The theoretical problem solved in this article is the calculation of thermodynamic parameters such as final temperature, distribution of the liquid and dry saturated vapour phases of the substance that are considered to be in thermodynamic equilibrium, and pressure of the system of several reaction products after adding to the system a certain amount of heat or the thermal effect released during rapid exothermic reaction in a closed volume that occurs so fast that it can be considered to be adiabatic, and when the volume of liquid reagents is several orders of magnitude less than the volume of the reactor. The general multi-substance problem is reduced to a theoretical problem for one substance of calculation thermodynamic parameters of system after adding a certain amount of heat that gives theoretically rigorous isochoric calculation. In this article, we substantiate our view that isochoric pass of calculation is more robust compared to seemingly more natural isobaric pass of calculation, if the later involves quite not trivial calculation of the adiabatic compression of a two-phase system (liquid - dry saturated vapour) that can pass itself into another kind of state (liquid - wet saturated vapour), which requires, apparently, more complex descriptions compared with isochoric calculation because the specific heat capacity of wet saturated vapour can be negative. The solved theoretical problem relates to a practical problem that has been a driver for our research as part of a design of the reactor of the titanium reduction from magnesium and titanium tetrachloride supplied into atmosphere of the reactor at high temperatures when both reagents are in gaseous state. The reaction is known to be exothermic with a high thermal effect, and estimate of the final temperature and pressure of the products of reaction, for instance, designing the reactor allows eliminating the possibility of the reaction products to penetrate backwards into supply tracts of the reagents

  7. A novel reverse flow reactor coupling endothermic and exothermic reactions. Part II: sequential reactor configuration for reversible endothermic reactions

    NARCIS (Netherlands)

    van Sint Annaland, M.; Scholts, H.A.R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2002-01-01

    The new reactor concept for highly endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible

  8. Theory of flame spread above solids. [fuel exothermic surface reactions

    Science.gov (United States)

    Sirignano, W. A.

    1974-01-01

    A theory for flame spread above a solid fuel is presented. The special case is considered whereby the oxidation is an exothermic surface reaction. The spreading rate is predicted as a function of the thermochemical properties, fuel-bed thickness, and convective velocity. Also, the theory predicts temperature, mass fraction, and heat flux as a function of position.

  9. Evaluation on thermal explosion induced by slightly exothermic interface reaction.

    Science.gov (United States)

    Yu, Ma-Hong; Li, Yong-Fu; Sun, Jin-Hua; Hasegawa, Kazutoshi

    2004-09-10

    An asphalt-salt mixture (ASM), which once caused a fire and explosion in a reprocessing plant, was prepared by imitating the real bituminization process of waste on a lab scale to evaluate its actual thermal hazards. Heat flux reaction calorimeters were used to measure the release of heat for the simulated ASM at a constant heating rate and at a constant temperature, respectively. Experimental results show that the reaction in the ASM below about 250 degrees C is a slightly exothermic interface reaction between the asphalt and the salt particles contained in the asphalt, and that the heat release rate increases sharply above about 250 degrees C due to melting of the salt particles. The reaction rates were formulated on the basis of an assumed reaction model, and the kinetic parameters were determined. Using the model with the kinetic parameters, temperature changes with time and drum-radius axes for the ASM-filled drum were numerically simulated assuming a one-dimensional infinite cylinder system, where the drum was being cooled at an ambient temperature of 50 degrees C. The minimum filling temperature, at which the runaway reaction (MFTRR) can occur for the simulated ASM in the drum is about 194 degrees C. Furthermore, a very good linear correlation exists between this MFTRR and the initial radius of salt particles formed in the bituminization product. The critical filling temperature to the runaway reaction is about 162 degrees C for the asphalt-salt mixture, containing zero-size salt particles, filled in the same drum at an ambient temperature of 50 degrees C. Thus, the runaway reaction will never occur in the drum filled with the asphalt-salt mixture under the conditions of the filling temperature below 162 degrees C and a constant ambient temperature of 50 degrees C. As a consequence, the ASM explosion occurred in the reprocessing plant likely was due to a slightly exothermically reaction and self heating.

  10. Enhanced Diffusion of Enzymes that Catalyze Exothermic Reactions.

    Science.gov (United States)

    Golestanian, Ramin

    2015-09-04

    Enzymes have been recently found to exhibit enhanced diffusion due to their catalytic activities. A recent experiment [C. Riedel et al., Nature (London) 517, 227 (2015)] has found evidence that suggests this phenomenon might be controlled by the degree of exothermicity of the catalytic reaction involved. Four mechanisms that can lead to this effect, namely, self-thermophoresis, boost in kinetic energy, stochastic swimming, and collective heating are critically discussed, and it is shown that only the last two can be strong enough to account for the observations. The resulting quantitative description is used to examine the biological significance of the effect.

  11. Dynamic response of a plane-symmetrical exothermic reaction center.

    Science.gov (United States)

    Meyer, J. W.; Oppenheim, A. K.

    1972-01-01

    ?sger,An analysis of the dynamic behavior of an idealized, plane-symmetrical exothermic reaction center is presented. The conservation equations for the reaction center are combined and yield a single integral equation expressing a nonlinear transfer function of the system for which the input is provided by a given time profile of the heat released per unit mass while the output gives the pressure pulse it generates under the restriction of plane-symmetrical motion. The solution is governed by a Daumk]hler number. For a given form of the exothermic power pulse profile, the dynamic behavior of the system is completely specified in terms of only this Daumk]hler number and the heat of reaction per unit mass of the combustible medium. Specific solutions are worked out for a set of typical elementary power pulse profiles, and the practical significance of the results is illustrated by their application to the problem of transition to detonation in an explosive gas.

  12. Dynamics of competitive reactions: endothermic proton transfer and exothermic substitution.

    Science.gov (United States)

    Ren, Jianhua; Brauman, John I

    2004-03-03

    Dynamics of an endothermic proton-transfer reaction, F(-) with dimethyl sulfoxide, and an endothermic proton-transfer reaction with a competing exothermic substitution (S(N)2) channel, F(-) with borane-methyl sulfide complex, were investigated using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR) and kinetic modeling. The two proton-transfer reactions have slightly positive and a small negative overall free energy changes, respectively. Energy-dependent rate constants were measured as a function of F(-) ion translational energy, and the resulting kinetics were modeled with the RRKM (Rice-Ramsperger-Kassel-Marcus) theory. The observed rate constants for the proton-transfer reactions of F(-) with dimethyl sulfoxide and with borane-methyl sulfide complex are identical, with a value of 0.17 x 10(-9) cm(3) molecule(-1) s(-1); for the S(N)2 reaction, k = 0.90 x 10(-9) cm(3) molecule(-1) s(-1) at 350 K. Both proton-transfer reactions have positive entropy changes in the forward direction and show positive energy dependences. The competing S(N)2 reaction exhibits negative energy dependence and becomes less important at higher energies. The changes of the observed rate constants agree with RRKM theory predictions for a few kcal/mol of additional kinetic energy. The dynamic change of the branching ratio for the competing proton transfer and the substitution reactions results from the competition between the microscopic rate constants associated with each channel.

  13. Potential for exothermic chemical reactions in waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Van Tuyl, H.H.

    1983-02-03

    The potential for exothermic chemical reactions in waste tanks at Hanford is discussed. Organic chemicals have been added to Hanford waste tanks, particularly as ferrocyanides and when processing sludges at B Plant. Recent planned or ongoing activities involving stored wastes have possibly increased the potential for reaction of these wastes with nitrate salts in the waste tanks. Risk evaluations appear to be deficient in assessing the consequences of a deflagration, and in determining the probability of either a deflagration or detonation. The present question is whether current plans and recent safety-related documentation have given proper consideration to the available information about organic compounds in waste tanks. The principal organic additions to Hanford waste tanks are 1200 tonnes of organic carbon'' and 500 tonnes of Ni{sub 2}Fe(CN){sub 6}. 13 refs.

  14. An Experiment to Illustrate the Hazards of Exothermic Reaction Scale-Up

    Science.gov (United States)

    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…

  15. Characterization of hot spots in microstructured reactors for fast and exothermic reactions in mixing regime

    OpenAIRE

    Haber, Julien; Kashid, Madhavanand N.; Borhani, Navid; Jiang, Bo; Maeder, Thomas; Thome, John Richard; Renken, Albert; Kiwi-Minsker, Lioubov

    2012-01-01

    The intensification of fast exothermic reactions can be achieved by using microstructured reactors (MSR) which provide improved mass & heat transfer rates leading to higher overall reaction kinetics. But for highly exothermic reactions the heat evacuation becomes not efficient enough and unwanted hot spots are formed. In this study, first the mixing in MSR is quantified for different geometries and then temperature profiles are measured using a novel quantitative IR-thermometry method. The re...

  16. Determination of the initial exothermic reaction of shredded tyres with wire content.

    Science.gov (United States)

    Sellasie, Kassahun G; Moo-Young, Horace K; Lloyd, Thomas

    2004-10-01

    This paper presents the cause of exothermic reactions in shredded tyre with exposed wire content in shredded tyre piles. Data indicate that the oxidation of exposed steel wires is the exothermic reaction in shredded tyre embankments. This would lead to spontaneous combustion. Reaction of the steel with the sulphur or the carbon black appears not to be the source of the exothermic. Laboratory tests have been conducted to determine the heat transfer properties of the materials that compose tyres (i.e., tyre rubber and wires) by using a hot-plate apparatus. In addition, one-dimensional heat conduction experiments were conducted to compare the flow of heat through the materials while varying the physical and environmental conditions. The physical conditions were the size of tyre shred, water content, and wire contents. An exothermic reaction occurred when exposed wire was present but not when it was absent. A one-dimensional heat transfer equation was developed, and parametric studies were conducted to verify the laboratory model. Exothermic reaction was found to increase linearly with temperature, size and shape of the shredded tyres, density, amount of wire in shredded tyres, and water content.

  17. Methods of conducting simultaneous exothermic and endothermic reactions

    Science.gov (United States)

    Tonkovich, Anna Lee [Marysville, OH; Roberts, Gary L [West Richland, WA; Perry, Steven T [Galloway, OH; Fitzgerald, Sean P [Columbus, OH

    2005-11-29

    Integrated Combustion Reactors (ICRs) and methods of making ICRs are described in which combustion chambers (or channels) are in direct thermal contact to reaction chambers for an endothermic reaction. Superior results were achieved for combustion chambers which contained a gap for free flow through the chamber. Particular reactor designs are also described. Processes of conducting reactions in integrated combustion reactors are described and results presented. Some of these processes are characterized by unexpected and superior results.

  18. Optimal Homotopy Asymptotic Solution for Exothermic Reactions Model with Constant Heat Source in a Porous Medium

    Directory of Open Access Journals (Sweden)

    Fazle Mabood

    2015-01-01

    Full Text Available The heat flow patterns profiles are required for heat transfer simulation in each type of the thermal insulation. The exothermic reaction models in porous medium can prescribe the problems in the form of nonlinear ordinary differential equations. In this research, the driving force model due to the temperature gradients is considered. A governing equation of the model is restricted into an energy balance equation that provides the temperature profile in conduction state with constant heat source on the steady state. The proposed optimal homotopy asymptotic method (OHAM is used to compute the solutions of the exothermic reactions equation.

  19. Self-exothermic reaction prompted synthesis of single-layered graphene quantum dots at room temperature.

    Science.gov (United States)

    Chen, Bin Bin; Li, Rong Sheng; Liu, Meng Li; Zhang, Hong Zhi; Huang, Cheng Zhi

    2017-05-02

    The easy fabrication of single-layered graphene quantum dots (s-GQDs) still faces challenge. Herein, we report an efficient route to fabricate s-GQDs within 5 min at room temperature by introducing a simple self-exothermic reaction. The as-prepared s-GQDs can specifically bind with aluminium ions to produce an aggregation-induced emission enhancement effect.

  20. A catalytically active membrane reactor for fast, exothermic, heterogeneously catalysed reactions

    NARCIS (Netherlands)

    Veldsink, J.W.; Veldsink, J.W.; van Damme, Rudolf M.J.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1992-01-01

    A membrane reactor with separated feed of reactants is demonstrated as a promising contractor type when dealing with heterogenously catalysed, very fast and exothermic gas phase reactions. Due to the separation of reactants a good control of the system is obtained, because process variables can be

  1. Minimally invasive thermotherapy method for tumor treatment based on an exothermic chemical reaction.

    Science.gov (United States)

    Deng, Zhong-Shan; Liu, Jing

    2007-01-01

    In tumor thermotherapy treatment, it is very difficult to achieve the objective of exactly killing the tumor while minimizing the injury of healthy tissues or organs surrounding the tumor. In this study, we describe a new minimally invasive thermotherapy protocol for tumor treatment using heat released from an exothermic chemical reaction, which can safely deliver a totally localized and uniform heating to exactly kill the tumor. Both in vitro and in vivo experiments were performed to test the feasibility of this thermotherapy method based on an exothermic chemical reaction. After injection of only a small amount of matched reactants into the target tissue by medical syringes, an exothermic reaction takes place, and then releases tremendous heat to elevate the temperature to its thermally lethal value. Compared with most of the currently existing thermotherapy strategies, this heating is highly localized, completely safe and uniform, which will remarkably reduce the thermal damage and mechanical trauma to the surrounding healthy tissues. This study opens the clinical possibilities for tumors to be treated in a minimally invasive way by a thermotherapy treatment based on an exothermic chemical reaction.

  2. A Role-Play to Illustrate the Energy Changes Occurring in an Exothermic Reaction.

    Science.gov (United States)

    Tyas, Toby; Cabot, John

    1999-01-01

    Describes a role-play activity designed to help students understand the energy changes involved in an exothermic reaction by modeling the concepts of bond-breaking takes in energy, activation energy, temperature rise, and bond breaking gives out energy. (WRM)

  3. Three-dimensional convection-driven fronts of the exothermic chlorite-tetrathionate reaction.

    Science.gov (United States)

    Schuszter, Gábor; Pótári, Gábor; Horváth, Dezső; Tóth, Ágota

    2015-06-01

    Horizontally propagating autocatalytic reaction fronts in fluids are often accompanied by convective motion in the presence of gravity. We experimentally and numerically investigate the stable complex three-dimensional pattern arising in the exothermic chlorite-tetrathionate reaction as a result of the antagonistic thermal and solutal contribution to the density change. By particle image velocimetry measurements, we construct the flow field that stabilizes the front structure. The calculations applied for incompressible fluids using the empirical rate-law model reproduce the experimental observations with good agreement.

  4. Effects of exothermic chemical reaction on the photoacoustic effect from particulate suspensions.

    Science.gov (United States)

    Park, Han Jung; Wu, Binbin; Diebold, Gerald J

    2011-03-28

    Irradiation of chemically reactive particulate suspensions by high power, pulsed laser radiation initiates reactions at the sites of the particles so that besides the absorbed optical energy, chemical energy is liberated. In addition to the release of chemical energy, chemical reaction can result in gas production both of which result in enhancement in the amplitude of the photoacoustic effect. Here we report photoacoustic and transient grating experiments with colloidal C in mixtures of H(2)O(2) with H(2)O. The inclusion of H(2)O(2) in an aqueous C suspension changes the normally endothermic reaction of C with H(2)O into the highly exothermic reaction of C with H(2)O(2) leading to both an enhanced photoacoustic effect and an increase in light emission from the suspension. As well, laser-initiated exothermic reactions in suspensions of C with CH(3)NO(2) and particulate Hg(CNO)(2) in H(2)O are shown to result in greatly enhanced photoacoustic signal amplitudes.

  5. Measurement of the temperature profile of an exothermic autocatalytic reaction front.

    Science.gov (United States)

    Martin, J; Rakotomalala, N; Talon, L; Salin, D

    2009-11-01

    Autocatalytic reactions may propagate as solitary waves, namely, at a constant front velocity and with a stationary concentration profile, resulting from a balance between molecular diffusion and chemical reaction. When the reaction is exothermic, a thermal wave is linked to the chemical front. As the thermal diffusivity is nearly two orders of magnitude larger than the molecular one, the temperature profile spreads over length scales (mm) two orders of magnitude larger than the concentration one. Using an infrared camera, we measure the temperature profiles for a chlorite-tetrathionate autocatalytic reaction. The profiles are compared quantitatively to lattice Bhatnagar-Gross-Krook (BGK) numerical simulations. Our analysis also accounts for the lack of observation of the thermal wave for the iodate arsenous acid reaction.

  6. Flow-field development during finger splitting at an exothermic chemical reaction front.

    Science.gov (United States)

    Sebestíková, L; D'Hernoncourt, J; Hauser, M J B; Müller, S C; De Wit, A

    2007-02-01

    Fingertip splitting may be observed at chemical reaction fronts subject to buoyancy-induced Rayleigh-Taylor fingering, as investigated in ascending fronts of the iodate-arsenous acid reaction in vertical Hele-Shaw cells. We study the properties of the flow-field evolution during a tip-splitting event both experimentally and theoretically. Experimental particle-image velocimetry techniques show that the flow field associated to a finger displays a quadrupole of vortices. The evolution of the flow field and the reorganization of the vortices after a tip-splitting event are followed experimentally in detail. Numerical integration of a model reaction-diffusion-convection system for an exothermic reaction taking into account possible heat losses through the walls of the reactor shows that the nonlinear properties of the flow field are different whether the walls are insulating or conducting. In insulating systems, the flow field inside one finger features only one pair of vortices. A quadrupole of flow vortices arranged around a saddle-node structure similar to the one observed experimentally is obtained in the presence of heat losses suggesting that heat effects, even if of very small amplitude, are important in understanding the nonlinear properties of fingering of exothermic chemical fronts.

  7. Influence of exothermic chemical reactions on laser-induced shock waves.

    Science.gov (United States)

    Gottfried, Jennifer L

    2014-10-21

    Differences in the excitation of non-energetic and energetic residues with a 900 mJ, 6 ns laser pulse (1064 nm) have been investigated. Emission from the laser-induced plasma of energetic materials (e.g. triaminotrinitrobenzene [TATB], cyclotrimethylene trinitramine [RDX], and hexanitrohexaazaisowurtzitane [CL-20]) is significantly reduced compared to non-energetic materials (e.g. sugar, melamine, and l-glutamine). Expansion of the resulting laser-induced shock wave into the air above the sample surface was imaged on a microsecond timescale with a high-speed camera recording multiple frames from each laser shot; the excitation of energetic materials produces larger heat-affected zones in the surrounding atmosphere (facilitating deflagration of particles ejected from the sample surface), results in the formation of additional shock fronts, and generates faster external shock front velocities (>750 m s(-1)) compared to non-energetic materials (550-600 m s(-1)). Non-explosive materials that undergo exothermic chemical reactions in air at high temperatures such as ammonium nitrate and magnesium sulfate produce shock velocities which exceed those of the inert materials but are less than those generated by the exothermic reactions of explosive materials (650-700 m s(-1)). The most powerful explosives produced the highest shock velocities. A comparison to several existing shock models demonstrated that no single model describes the shock propagation for both non-energetic and energetic materials. The influence of the exothermic chemical reactions initiated by the pulsed laser on the velocity of the laser-induced shock waves has thus been demonstrated for the first time.

  8. TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

    National Research Council Canada - National Science Library

    Marta Ziemnicka-Sylwester

    2013-01-01

    .... The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic "in situ" reaction of TiB2 formation and the "tailing" synthesis of boron carbide characterized by weak exothermicity...

  9. Middle atmosphere heating by exothermic chemical reactions involving odd-hydrogen species

    Science.gov (United States)

    Mlynczak, Martin G.; Solomon, Susan

    1991-01-01

    The rate of heating which occurs in the middle atmosphere due to four exothermic reactions involving members of the odd-hydrogen family is calculated. The following reactions are considered: O + OH yields O2 + H; H + O2 + M yields HO2 + M; H + O3 yields OH + O2; and O + HO2 yields OH + O2. It is shown that the heating rates due to these reactions rival the oxygen-related heating rates conventionally considered in middle-atmosphere models. The conversion of chemical potential energy into molecular translational energy (heat) by these odd-hydrogen reactions is shown to be a significant energy source in the middle atmosphere that has not been previously considered.

  10. Fingering of exothermic reaction-diffusion fronts in Hele-Shaw cells with conducting walls.

    Science.gov (United States)

    D'Hernoncourt, J; Kalliadasis, S; De Wit, A

    2005-12-15

    We consider the influence of heat losses through the walls of a Hele-Shaw cell on the linear stability and nonlinear dynamics of exothermic chemical fronts whose solutal and thermal contributions to density changes have the same signs. Our analysis is based on the reaction-diffusion-convection equations obtained from the Darcy-Boussinesq approximation. The parameters governing the equations are the Damkohler number, a kinetic parameter d, the Lewis number Le, the thermal-expansion coefficient gammaT, and a heat-transfer coefficient alpha which measures heat losses through the walls. We show that for thermally insulating walls, the temperature profile is a front that follows the concentration profile, while in the presence of heat losses, the temperature profile becomes a pulse that leads to a nonmonotonic density profile which in turn may lead to a destabilization of an otherwise stable front.

  11. Reply to Comment on "Enhanced diffusion of enzymes that catalyze exothermic reactions"

    CERN Document Server

    Golestanian, Ramin

    2016-01-01

    Catalytically active enzymes have recently been observed to exhibit enhanced diffusion. In a recent work [C. Riedel et al., Nature 517, 227 (2015)], it has been suggested that this phenomenon is correlated with the degree of exothermicity of the reaction, and a mechanism was proposed to explain the phenomenon based on channeling the released heat into the center of mass kinetic energy of the enzyme. I addressed this question by comparing four different mechanisms, and concluded that collective heating is the strongest candidate out of those four to explain the phenomenon, and in particular, several orders of magnitude stronger than the mechanism proposed by Riedel et al. In a recent preprint (arXiv:1608.05433), K. Tsekouras, C. Riedel, R. Gabizon, S. Marqusee, S. Presse, and C. Bustamante present a comment on my paper [R. Golestanian, Phys. Rev. Lett. 115, 108102 (2015); arXiv:1508.03219], which I address here in this reply.

  12. Exothermic reaction in zeolite hemostatic dressings: QuikClot ACS and ACS+.

    Science.gov (United States)

    Arnaud, Françoise; Tomori, Toshiki; Carr, Walter; McKeague, Anne; Teranishi, Kohsuke; Prusaczyk, Keith; McCarron, Richard

    2008-10-01

    Zeolites have hemostatic properties used to stop bleeding in severe hemorrhage. Manufactured QuikClot is an approved zeolite-based hemostatic agent for battlefield use. The exothermic reaction associated with QuikClot as loose granules or as granules packaged in a mesh bag has potential burn effects; this led to the development of a formulation of "cooler" non-exothermic QuikClot. The goal of this study was to compare the elevation of temperature of these formulations upon contact with blood. Following full transection of the femoral vasculature, anesthetized Yorkshire pigs (n = 15) (28.8 +/- 1.5 kg) were hemorrhaged for 2 min and treated with 100 g of bagged QuikClot (Advanced Clotting Sponge (ACS) (n = 4)) or a modified non-exothermic formulation (ACS+ (n = 11)). Vital signs and temperature at the dressing/tissue interface were continuously recorded for 3 h. Additional procedures were used to examine effects of different ratios of blood to zeolite on temperature elevation. Total post-treatment blood loss was comparable for ACS+_E and ACS_E groups (overall average: 18.6 +/- 10.5% EBV). Temperature recorded at the dressing/tissue interface was significantly lower with ACS+ vs. ACS (40.3 +/- 1.8 vs. 61.4 +/- 10.7 degrees C, respectively, p < 0.01) and was 3.2 +/- 2.6 degrees C higher than rectal temperature (38.0 +/- 0.7 degrees C, p < 0.01). Survival at endpoint (7/11 vs. 4/4) and average survival time (134 +/- 64 vs. 180 min) were greater for both ACS+ and ACS in comparison to Standard Dressing. The wound temperature with ACS was reduced with greater blood to product ratios and this pattern was paralleled with in vitro measurements. The lower heat release with ACS+ compared to ACS was confirmed in an animal model and ACS+ had similar efficacy in arresting bleeding when compared to Standard Dressing.

  13. Evaluation of kinetic parameters of exothermic gas/solid-reactions by the ignition point method; Bestimmung kinetischer Parameter exothermer Gas/Feststoff-Reaktionen mit der Zuendpunktsmethode

    Energy Technology Data Exchange (ETDEWEB)

    Hein, O.; Jess, A. [Technische Hochschule Aachen (Germany). Inst. fuer Technische Chemie und Makromolekulare Chemie

    2000-01-01

    The determination of kinetic constants of heterogeneous reactions is usually performed in tubular flow reactors under isothermal and stationary reaction conditions. This is often time-consuming and difficult. For example, in case of strong exothermic reactions, temperature gradients up to the ignition of the fixed-bed are hard to avoid, and therefore expensive reactors with internal or external gas recycle are needed. The effect of ignition can also be used to characterize the reactivity of solid fuels and the activity of catalysts, respectively. A well-known method for a simple, fast and accurate determination of the ignition temperature in a lab-scale tubular flow reactor is already described in literature. Yet, the ignition point method is up to now only used as a qualitative measure for the (relative) reactivity of solid fuels and activity of catalysts. Therefore, an attempt was made to extend this method towards a quantitative characterization of the kinetics of exothermic heterogeneous reaction systems, i.e. for a determination of the activation energy and the preexponential factor. The basic idea is thereby to alter the ignition point by a defined variation of the operation conditions such as particle diameter, heating rate as well as of the composition and flow rate of the reacting gas mixture. The resulting data are then used to calculate the kinetic constants based on the theory of ignition of exothermic reactions. The combustion of different cokes as well as of carbon deposits on a Pt-catalyst were selected as model reactions for gas/solid-reactions. In addition, the oxidation of methane on a Pt-catalyst was investigated. The experiments on the influence of the operation conditions show that the gas composition - in case of combustion of coke the oxygen content - has the strongest influence on the ignition temperature. This method is therefore very suitable to determine kinetic constants. To prove the accuracy of this method, the kinetic data were also

  14. Using Different Conceptual Change Methods Embedded within 5E Model: A Sample Teaching of Endothermic-Exothermic Reactions

    Science.gov (United States)

    Turk, Fatma; Calik, Muammer

    2008-01-01

    Since Widodo, Duit and Muller (2002) addressed that there is a gap between teacher's theoretical knowledge and their practical classroom constructivist behavior, we presented a sample teaching activity about Endothermic-Exothermic Reactions for teacher usage. Therein, the aim of this study is to design a 5E model to include students' alternative…

  15. Shock-wave-like structures induced by an exothermic neutralization reaction in miscible fluids.

    Science.gov (United States)

    Bratsun, Dmitry; Mizev, Alexey; Mosheva, Elena; Kostarev, Konstantin

    2017-11-01

    We report shock-wave-like structures that are strikingly different from previously observed fingering instabilities, which occur in a two-layer system of miscible fluids reacting by a second-order reaction A+B→S in a vertical Hele-Shaw cell. While the traditional analysis expects the occurrence of a diffusion-controlled convection, we show both experimentally and theoretically that the exothermic neutralization reaction can also trigger a wave with a perfectly planar front and nearly discontinuous change in density across the front. This wave propagates fast compared with the characteristic diffusion times and separates the motionless fluid and the area with anomalously intense convective mixing. We explain its mechanism and introduce a new dimensionless parameter, which allows to predict the appearance of such a pattern in other systems. Moreover, we show that our governing equations, taken in the inviscid limit, are formally analogous to well-known shallow-water equations and adiabatic gas flow equations. Based on this analogy, we define the critical velocity for the onset of the shock wave which is found to be in the perfect agreement with the experiments.

  16. Shock-wave-like structures induced by an exothermic neutralization reaction in miscible fluids

    Science.gov (United States)

    Bratsun, Dmitry; Mizev, Alexey; Mosheva, Elena; Kostarev, Konstantin

    2017-11-01

    We report shock-wave-like structures that are strikingly different from previously observed fingering instabilities, which occur in a two-layer system of miscible fluids reacting by a second-order reaction A +B →S in a vertical Hele-Shaw cell. While the traditional analysis expects the occurrence of a diffusion-controlled convection, we show both experimentally and theoretically that the exothermic neutralization reaction can also trigger a wave with a perfectly planar front and nearly discontinuous change in density across the front. This wave propagates fast compared with the characteristic diffusion times and separates the motionless fluid and the area with anomalously intense convective mixing. We explain its mechanism and introduce a new dimensionless parameter, which allows to predict the appearance of such a pattern in other systems. Moreover, we show that our governing equations, taken in the inviscid limit, are formally analogous to well-known shallow-water equations and adiabatic gas flow equations. Based on this analogy, we define the critical velocity for the onset of the shock wave which is found to be in the perfect agreement with the experiments.

  17. The examination of analysis and evaluation model and analysis method of the exothermic reaction between solvent and nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Yoshihiko; Hirumachi, Suguru [Japan Nuclear Cycle Development Institute, Safety Engineering Group, Health and Safety Division, Tokai Works, Tokai, Ibaraki (Japan); Koyama, Kazuya; Miki, Junichi

    1999-02-01

    In advanced nuclear fuel recycling technological R and D, the upgrading research in the fast reactor fuel cycle which the transuranics is separated and collected for the high-level activity liquid waste and is made to burn using fast reactor is carried out. In CMPO which is new extracting agent that the use is examined and TRUEX solvent which is the CMPO mixed solvent, for the purpose of evaluating accurately exothermic reaction behavior and gas generation behavior of the exothermic reaction between solvent and nitric acid in the evaporator in research installation in the future, analysis and evaluation model and investigation and examination of the physical property necessary for the analysis evaluation were carried out, while analysis and evaluation example of the exothermic reaction between solvent and nitric acid in the evaporator are investigated, and the test calculation was carried out. On the exothermic reaction between organic solvent and nitric acid in the evaporator examples, of analysis and evaluation carried out until now were investigated. It was found that there are a method for deducing the temperature of self accelerated reaction from the steady heat balance equation and a method for doing a transient analysis of temperature rise by exothermic reaction of nitric acid with organic solvent, that is, a method for deciding the reaction rate of exothermic reaction in proportion to various conditions. It was then confirmed that the method for doing the transient analysis of temperature rise by exothermic reaction between organic solvent and nitric acid is the most safe side and the most realistic evaluation technique in the method of the superscription. Based on the examination of the superscription, it carried out preparation of analysis and evaluation model of the exothermic reaction between organic solvent and nitric acid in the evaporator and examination of the analysis method, and it became possible that it realistically handles the behavior of the

  18. Self-propagating exothermic reaction analysis in Ti/Al reactive films using experiments and computational fluid dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Seema, E-mail: seema.sen@tu-ilmenau.de [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Lake, Markus; Kroppen, Norman; Farber, Peter; Wilden, Johannes [Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Schaaf, Peter [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany)

    2017-02-28

    Highlights: • Development of nanoscale Ti/Al multilayer films with 1:1, 1:2 and 1:3 molar ratios. • Characterization of exothermic reaction propagation by experiments and simulation. • The reaction velocity depends on the ignition potentials and molar ratios of the films. • Only 1Ti/3Al films exhibit the unsteady reaction propagation with ripple formation. • CFD simulation shows the time dependent atom mixing and temperature flow during exothermic reaction. - Abstract: This study describes the self-propagating exothermic reaction in Ti/Al reactive multilayer foils by using experiments and computational fluid dynamics simulation. The Ti/Al foils with different molar ratios of 1Ti/1Al, 1Ti/2Al and 1Ti/3Al were fabricated by magnetron sputtering method. Microstructural characteristics of the unreacted and reacted foils were analyzed by using electronic and atomic force microscopes. After an electrical ignition, the influence of ignition potentials on reaction propagation has been experimentally investigated. The reaction front propagates with a velocity of minimum 0.68 ± 0.4 m/s and maximum 2.57 ± 0.6 m/s depending on the input ignition potentials and the chemical compositions. Here, the 1Ti/3Al reactive foil exhibits both steady state and unsteady wavelike reaction propagation. Moreover, the numerical computational fluid dynamics (CFD) simulation shows the time dependent temperature flow and atomic mixing in a nanoscale reaction zone. The CFD simulation also indicates the potentiality for simulating exothermic reaction in the nanoscale Ti/Al foil.

  19. Safe design of cooled tubular reactors for exothermic multiple reactions: Multiple-reaction networks

    NARCIS (Netherlands)

    Westerink, E.J.; Westerterp, K.R.

    1988-01-01

    The model of the pseudo-homogeneous, one-dimensional cooled tubular reactor is applied to a multiple-reaction network. It is demonstrated for a network which consists of two parallel and two consecutive reactions. Three criteria are developed to obtain an integral yield which does not deviate more

  20. A novel reverse flow reactor coupling endothermic and exothermic reactions: an experimental study

    NARCIS (Netherlands)

    van Sint Annaland, M.; Nijssen, R.C.

    2002-01-01

    A new reactor concept is studied for highly endothermic heterogeneously catalysed gas phase reactions at high temperatures with rapid but reversible catalyst deactivation. The reactor concept aims to achieve an indirect coupling of energy necessary for endothermic reactions and energy released by

  1. Safe design of cooled tubular reactors for exothermic, multiple reactions. Consecutive reactions

    NARCIS (Netherlands)

    Westerterp, K.R.; Overtoom, R.R.M.

    1985-01-01

    The model of the pseudo-homogeneous, one-dimensional, cooled tubular reactor is applied to two consecutive, irreversible first order reactions. A criterion is derived to obtain a desired integral yield. Based on this criterion three requirements are formulated, which enable us to choose the relevant

  2. The Reaction between Bromine and the Water Dimer and the Highly Exothermic Reverse Reaction.

    Science.gov (United States)

    Li, Guoliang; Wang, Hui; Li, Qian-Shu; Xie, Yaoming; Schaefer, Henry F

    2016-01-15

    The entrance complex, transition state, and exit complex for the bromine atom plus water dimer reaction Br + (H2O)2 → HBr + (H2O)OH and its reverse reaction have been investigated using the CCSD(T) method with correlation consistent basis sets up to cc-pVQZ-PP. Based on the CCSD(T)/cc-pVQZ-PP results, the reaction is endothermic by 31.7 kcal/mol. The entrance complex Br⋯(H2O)2 is found to lie 6.5 kcal/mol below the separated reactants. The classical barrier lies 28.3 kcal/mol above the reactants. The exit complex HBr⋯(H2O)OH is bound by 6.0 kcal/mol relative to the separated products. Compared with the corresponding water monomer reaction Br + H2 O → HBr + OH, the second water molecule lowers the relative energies of the entrance complex, transition state, and exit complex by 3.0, 3.8, and 3.7 kcal/mol, respectively. Both zero-point vibrational energies and spin-orbit coupling effects make significant changes to the above classical energetics. Including both effects, the predicted energies relation to separated Br + (H2O)2 are -3.0 kcal/mol [Br···(H2O)2 ], 28.2 kcal/mol [transition state], 26.4 kcal/mol [HBr···(H2O)OH], and 30.5 kcal/mol [separated HBr + (H2O)OH]. The potential energy surface for the Br + (H2O)2 reaction is related to that for the valence isoelectronic Cl + (H2O)2 system but radically different from the F + (H2O)2 system. © 2015 Wiley Periodicals, Inc.

  3. Interfacial chemistry in Al/CuO reactive nanomaterial and its role in exothermic reaction.

    Science.gov (United States)

    Kwon, Jinhee; Ducéré, Jean Marie; Alphonse, Pierre; Bahrami, Mehdi; Petrantoni, Marine; Veyan, Jean-Francois; Tenailleau, Christophe; Estève, Alain; Rossi, Carole; Chabal, Yves J

    2013-02-01

    Interface layers between reactive and energetic materials in nanolaminates or nanoenergetic materials are believed to play a crucial role in the properties of nanoenergetic systems. Typically, in the case of Metastable Interstitial Composite nanolaminates, the interface layer between the metal and oxide controls the onset reaction temperature, reaction kinetics, and stability at low temperature. So far, the formation of these interfacial layers is not well understood for lack of in situ characterization, leading to a poor control of important properties. We have combined in situ infrared spectroscopy and ex situ X-ray photoelectron spectroscopy, differential scanning calorimetry, and high resolution transmission electron microscopy, in conjunction with first-principles calculations to identify the stable configurations that can occur at the interface and determine the kinetic barriers for their formation. We find that (i) an interface layer formed during physical deposition of aluminum is composed of a mixture of Cu, O, and Al through Al penetration into CuO and constitutes a poor diffusion barrier (i.e., with spurious exothermic reactions at lower temperature), and in contrast, (ii) atomic layer deposition (ALD) of alumina layers using trimethylaluminum (TMA) produces a conformal coating that effectively prevents Al diffusion even for ultrathin layer thicknesses (∼0.5 nm), resulting in better stability at low temperature and reduced reactivity. Importantly, the initial reaction of TMA with CuO leads to the extraction of oxygen from CuO to form an amorphous interfacial layer that is an important component for superior protection properties of the interface and is responsible for the high system stability. Thus, while Al e-beam evaporation and ALD growth of an alumina layer on CuO both lead to CuO reduction, the mechanism for oxygen removal is different, directly affecting the resistance to Al diffusion. This work reveals that it is the nature of the monolayer

  4. Size effect in self-propagating exothermic reaction of Al/Ni multilayer block on a Si wafer

    Science.gov (United States)

    Namazu, Takahiro; Ito, Shun; Kanetsuki, Shunsuke; Miyake, Shugo

    2017-06-01

    In this paper, the threshold size of sputtered Al/Ni multilayer blocks required for inducing a self-propagating exothermic reaction on a Si wafer is described. An Al/Ni multilayer film with a bilayer thickness of 100 nm is deposited on a Si wafer, and then micronsized Al/Ni multilayer blocks from the film are fabricated using a focused ion beam. By inducing small sparks in the vicinity of the blocks, we investigate reactivity. From scanning electron microscopy observations, we confirm that Al/Ni multilayer blocks with high aspect ratios and small widths can react easily. The effect of Al/Ni multilayer block size on reactivity is discussed from the viewpoint of heat conduction from the block to a Si wafer during an exothermic reaction.

  5. Calibration of temperature measurement by infrared pyrometry in microwave heating of powder materials: an exothermic reaction based approach.

    Science.gov (United States)

    Luo, S D; Yang, Y F; Schaffer, G B; Qian, M

    2013-01-01

    Accurate temperature measurement remains a challenge for microwave heating of powder materials. We propose a temperature calibration method based on exothermic reactions and the resultant thermal runaway that occurs during microwave heating. The approach was demonstrated on microwave heating of four titanium alloys. Differential scanning calorimetry was used to determine the threshold reaction temperature for each selected titanium alloy. This served as a standard for the microwave heating of these titanium alloys. Infrared pyrometric temperature measurements were then calibrated by comparing the starting temperature of each thermal runaway event with the threshold reaction temperature.

  6. Recovery of work from exothermic chemical reaction systems by means of turbine expansion

    Energy Technology Data Exchange (ETDEWEB)

    Greeff, I.L.

    2003-12-08

    It is evident that a unique design approach or methodology is needed to develop flow sheet configurations for chemical reaction systems that use turbine expanders to recover reaction heat. It is the aim of this work to address this need by finding a methodology that will lend structure to the development and analysis of the flow sheets for the mentioned systems. Many factors have to be taken into consideration, both relating to the requirements of the chemical process and the requirements of the power cycle created using the process gas. For example, a reasonable pressure ratio is required over compression equipment in the case of a power cycle to produce power efficiently. The physical properties of the process gas, which becomes a working fluid, are also important. Furthermore, a thorough understanding of the role and behaviour of the expander within the chemical process is needed. Consequently, in this work the parameters that impact on the integrated systems will be identified and their roles investigated. Suitable criteria of performance for the integrated systems in question are also needed. In this regard the exergy method is particularly suited since it enables designs that will use energy resources more efficiently. The application of exergy analysis is illustrated and the strengths and limitations are discussed. The purpose of this research is achieved by conducting a number of case studies on different chemical reaction processes. These processes all comprise exothermic, high-pressure reactions, but otherwise differ significantly in terms of aspects such as reactor operation, separation techniques, reactant conversion, etc. The chemicals are also produced on a global scale using well-known processes. This makes realistic modelling of the processes possible. Process data are generated using simulations. The level of modelling and simulation is of a conceptual nature to investigate and illustrate fundamental principles, relations and trends. In Chapter 2

  7. A novel reverse flow reactor coupling endothermic and exothermic reactions. Part I: comparison of reactor configurations for irreversible endothermic reactions

    NARCIS (Netherlands)

    van Sint Annaland, M.; Scholts, H.A.R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2002-01-01

    A new reactor concept is studied for highly endothermic heterogeneously catalysed gas phase reactions at high temperatures with rapid but reversible catalyst deactivation. The reactor concept aims to achieve an indirect coupling of energy necessary for endothermic reactions and energy released by

  8. Fast and exothermic reaction of CO2 and Li3N into C-N-containing solid materials.

    Science.gov (United States)

    Hu, Yun Hang; Huo, Yan

    2011-10-27

    The conversion of CO(2) to valuable compounds, which is considered as an effective approach to solve the global warming, represents a great challenge due to the high stability and low reactivity of CO(2). Herein, thermodynamic calculations predicted the feasibility of exothermic reactions between CO(2) and Li(3)N into two important solid materials-carbon nitride and lithium cyanamide. Furthermore, the feasibility was confirmed by experiments, namely, the fast reaction between CO(2) and Li(3)N produced crystal lithium cyanamide and amorphous carbon nitrides. This provides a novel process to control CO(2) emissions.

  9. Exothermic waves in continua

    Science.gov (United States)

    Chernyi, G. G.

    Theoretical and experimental research related to the generation and propagation of exothermic waves in combustible gas mixtures as well as solid and liquid combustible media is reviewed. In particular, attention is given to detonation phenomena, the stationary structure of chemical detonation waves for various gas and condensed explosive models, discontinuous solutions for motions with exothermic discontinuities, and heat release in thermonuclear reactions. The discussion also covers frontal polymerization and crystallization waves, stationary combustion waves in systems with high-temperature self-propagating synthesis, and initiation of exothermic waves in continua with allowance for transfer processes.

  10. The catalytic nanodiode: detecting continuous electron flow at oxide-metal interfaces generated by a gas-phase exothermic reaction.

    Science.gov (United States)

    Park, Jeong Young; Somorjai, Gabor A

    2006-07-17

    Continuous flow of ballistic charge carriers is generated by an exothermic chemical reaction and detected using the catalytic metal-semiconductor Schottky diode. We obtained a hot electron current for several hours using two types of catalytic nanodiodes, Pt/TiO2 or Pt/GaN, during carbon monoxide oxidation at pressures of 100 Torr of O2 and 40 Torr of CO at 413-573 K. This result reveals that the chemical energy of an exothermic catalytic reaction is directly converted into hot electrons flux in the catalytic nanodiode. By heating the nanodiodes in He, we could measure the thermoelectric current which is in the opposite direction to the flow of the hot electron current. The chemicurrent is well correlated with the turnover rate of CO oxidation, which is separately measured with gas chromatography. The influence of the flow of hot charge carriers on the chemistry at the oxide-metal interface, and the turnover rate in the chemical reaction are discussed.

  11. TiB₂-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions.

    Science.gov (United States)

    Ziemnicka-Sylwester, Marta

    2013-05-10

    TiB₂-based ceramic matrix composites (CMCs) were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic "in situ" reaction of TiB₂ formation and the "tailing" synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB₂ vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB₂:B₄C molar ratio of 0.96, which corresponds to 40 vol% of TiB₂ in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB₂:B₄C molar ratio of 2.16 or above. Finally B13C₂ was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB₂ grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure), were obtained for material containing 80 vol% of TiB₂, fabricated using a graphite precursor of 2 μm.

  12. Temperature behavior of exothermic reaction of Al/Ni multilayer powder materials based on cold-rolling and pulverizing method

    Science.gov (United States)

    Kametani, Nagamasa; Izumi, Taisei; Miyake, Shugo; Kanetsuki, Shunsuke; Namazu, Takahiro

    2017-06-01

    In this paper, the characteristics of self-propagating exothermic reactions of an Al/Ni multilayer powder materials fabricated by a cold-rolling and powdering procedure are reported as initial findings of the first trial on a heat source for various applications with the energy-saving feature. Experimental results showed that, following the reaction of the developed Al/Ni multilayer powder materials in air atmosphere, the maximum temperature increased from approximately 1450 °C to over 1768 °C with increasing number of passes from 20 to 40 in cold-rolling. Furthermore, observations by scanning electron microscopy and crystallographic identification by X-ray diffraction measurements showed that the multilayer structure of powdered Al/Ni after 40 passes of cold-rolling was deformed, became thinner with below sub-micrometer thickness, and almost completely reacted to NiAl intermetallic compounds. It is possible that optimizing cold-rolling conditions enables us to control exothermic heat, which will be useful for heat sources.

  13. The exothermic HCl + OH·(H2O) reaction: removal of the HCl + OH barrier by a single water molecule.

    Science.gov (United States)

    Li, Guoliang; Wang, Hui; Li, Qian-Shu; Xie, Yaoming; Schaefer, Henry F

    2014-03-28

    The entrance complex, transition state, and exit complex for the title reaction have been investigated using the CCSD(T) method with correlation consistent basis sets up to cc-pVQZ. The stationary point geometries for the reaction are related to but different from those for the water monomer reaction HCl + OH → Cl + H2O. Our most important conclusion is that the hydrogen-bonded water molecule removes the classical barrier entirely. For the endothermic reverse reaction Cl + (H2O)2, the second water molecule lowers the relative energies of the entrance complex, transition state, and exit complex by about 4 kcal/mol. The title reaction is exothermic by 17.7 kcal/mol. The entrance complex HCl⋯OH·(H2O) is bound by 6.9 kcal/mol relative to the separated reactants. The classical barrier height for the reverse reaction is predicted to be 16.5 kcal/mol. The exit complex Cl⋯(H2O)2 is found to lie 6.8 kcal/mol below the separated products. The potential energy surface for the Cl + (H2O)2 reaction is radically different from that for the valence isoelectronic F + (H2O)2 system.

  14. Boundary-layer development and transition due to free-stream exothermic reactions in shock-induced flows

    Science.gov (United States)

    Hall, J. L.

    1974-01-01

    A study of the effect of free-stream thermal-energy release from shock-induced exothermic reactions on boundary-layer development and transition is presented. The flow model is that of a boundary layer developing behind a moving shock wave in two-dimensional unsteady flow over a shock-tube wall. Matched sets of combustible hydrogen-oxygen-nitrogen mixtures and inert hydrogen-nitrogen mixtures were used to obtain transition data over a range of transition Reynolds numbers from 1,100,000 to 21,300,000. The heat-energy is shown to significantly stabilize the boundary layer without changing its development character. A method for application of this data to flat-plate steady flows is included.

  15. Electron flow generated by gas phase exothermic catalytic reactions using a platinum-gallium nitride nanodiode.

    Science.gov (United States)

    Ji, Xiaozhong; Zuppero, Anthony; Gidwani, Jawahar M; Somorjai, Gabor A

    2005-04-27

    We report steady-state conversion of chemical reaction energy into hot electrons by ballistic injection into a platinum-gallium nitride (Pt/GaN) nanodiode during the platinum-catalyzed oxidation of carbon monoxide. Surface catalytic reactions of molecules from the gas phase generated continuous steady-state hot electron currents with energies at least that of Schottky barrier energy ( approximately 1 eV). These hot electron currents were observed on two different nanodiodes (Pt/TiO2 and Pt/GaN) and represent a new method of chemical energy conversion.

  16. Scientific Transactions No. 11 of the Institute of Mechanics, Moscow State University. [supersonic and hypersonic gas flow and the movement of gas with exothermic reactions

    Science.gov (United States)

    Gonor, A. L. (Editor)

    1982-01-01

    The results of flow around wings, the determination of the optimal form, and the interaction of the wake with the accompanying flow at supersonic and hypersonic speeds of the free-stream flow are given. Methods of numerical and analytical calculation of one dimensional unsteady and two dimensional steady motions of fuel-gas mixtures with exothermic reactions are also considered.

  17. Critical ignition conditions in exothermically reacting systems: first-order reactions

    Science.gov (United States)

    Filimonov, Valeriy Yu.

    2017-10-01

    In this paper, the comparative analysis of the thermal explosion (TE) critical conditions on the planes temperature-conversion degree and temperature-time was conducted. It was established that the ignition criteria are almost identical only at relatively small values of Todes parameter. Otherwise, the results of critical conditions analysis on the plane temperature-conversion degree may be wrong. The asymptotic method of critical conditions calculation for the first-order reactions was proposed (taking into account the reactant consumption). The degeneration conditions of TE were determined. The calculation of critical conditions for specific first-order reaction was made. The comparison of the analytical results obtained with the results of numerical calculations and experimental data showed that they are in good agreement.

  18. Thermal effects on the diffusive layer convection instability of an exothermic acid-base reaction front.

    Science.gov (United States)

    Almarcha, C; Trevelyan, P M J; Grosfils, P; De Wit, A

    2013-09-01

    A buoyancy-driven hydrodynamic instability appearing when an aqueous acid solution of HCl overlies a denser alkaline aqueous solution of NaOH in a vertically oriented Hele-Shaw cell is studied both experimentally and theoretically. The peculiarity of this reactive convection pattern is its asymmetry with regard to the initial contact line between the two solutions as convective plumes develop in the acidic solution only. We investigate here by a linear stability analysis (LSA) of a reaction-diffusion-convection model of a simple A+B→C reaction the relative role of solutal versus thermal effects in the origin and location of this instability. We show that heat effects are much weaker than concentration-related ones such that the heat of reaction only plays a minor role on the dynamics. Computation of density profiles and of the stability analysis eigenfunctions confirm that the convective motions result from a diffusive layer convection mechanism whereby a locally unstable density stratification develops in the upper acidic layer because of the difference in the diffusion coefficients of the chemical species. The growth rate and wavelength of the pattern are determined experimentally as a function of the Brinkman parameter of the problem and compare favorably with the theoretical predictions of both LSA and nonlinear simulations.

  19. RAPID BIOCATALYTIC POLYTRANSESTERIFICATION: REACTION KINETICS IN AN EXOTHERMIC REACTION. (R825338)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  20. Thermal analysis of the exothermic reaction between galvanic porous silicon and sodium perchlorate.

    Science.gov (United States)

    Becker, Collin R; Currano, Luke J; Churaman, Wayne A; Stoldt, Conrad R

    2010-11-01

    Porous silicon (PS) films up to ∼150 μm thick with specific surface area similar to 700 m(2)/g and pore diameters similar to 3 nm are fabricated using a galvanic corrosion etching mechanism that does not require a power supply. After fabrication, the pores are impregnated with the strong oxidizer sodium perchlorate (NaClO(4)) to create a composite that constitutes a highly energetic system capable of explosion. Using bomb calorimetry, the heat of reaction is determined to be 9.9 ± 1.8 and 27.3 ± 3.2 kJ/g of PS when ignited under N(2) and O(2), respectively. Differential scanning calorimetry (DSC) reveals that the energy output is dependent on the hydrogen termination of the PS.

  1. Theoretical Analysis of the Fragmentation of (CO)5: A Symmetry-Allowed Highly Exothermic Reaction that Follows a Stepwise Pathway.

    Science.gov (United States)

    Liu, Jiajun; Bao, Xiaoguang; Hrovat, David A; Borden, Weston Thatcher

    2015-12-04

    B3LYP and CCSD(T) calculations, using an aug-cc-pVTZ basis set, have been carried out on the fragmentation of 1,2,3,4,5-cyclopentanepentone, (CO)(5), to five molecules of CO. Although this reaction is calculated to be highly exothermic and is allowed to be concerted by the Woodward-Hoffmann rules, our calculations find that the D(5h) energy maximum is a multidimensional hilltop on the potential energy surface. This D(5h) hilltop is 16-20 kcal/mol higher in energy than a C(2) transition structure for the endothermic cleavage of (CO)(5) to (CO)(4) + CO and 11-15 kcal/mol higher than a C(s) transition structure for the loss of two CO molecules. The reasons for the very high energy of the D(5h) hilltop are discussed, and the geometries of the two lower energy transition structures are rationalized on the basis of mixing of the e(2)' HOMO and the a(2)″ LUMO of the hilltop.

  2. Four-dimensional quantum study on exothermic complex-forming reactions: Cl- + CH3Br-->ClCH3+Br-.

    Science.gov (United States)

    Hennig, Carsten; Schmatz, Stefan

    2005-06-15

    The exothermic gas-phase bimolecular nucleophilic substitution (S(N)2) reaction Cl(-)+CH(3)Br (upsilon1',upsilon2',upsilon3')-->ClCH(3) (upsilon1,upsilon2,upsilon3)+Br- and the corresponding endothermic reverse reaction have been studied by time-independent quantum scattering calculations in hyperspherical coordinates on a coupled-cluster potential-energy surface. The dimensionality-reduced model takes four degrees of freedom into account [Cl-C and C-Br stretching modes (quantum numbers upsilon3' and upsilon3); totally symmetric modes of the methyl group, i.e., C-H stretching (upsilon1' and upsilon1) and umbrella bending vibrations (upsilon2' and upsilon2)]. Diagonalization of the Hamiltonian was performed employing the Lanczos algorithm with a variation of partial reorthogonalization. A narrow grid in the total energy was employed so that long-living resonance states could be resolved and extracted. While excitation of the reactant umbrella bending mode already leads to a considerable enhancement of the reaction probability, its combination with vibrational excitation of the broken C-Br bond, (0, 1, 1), results in a strong synergic effect that can be rationalized by the similarity with the classical transitional normal mode. Exciting the C-H stretch has a non-negligible effect on the reaction probability, while for larger translational energies this mode follows the expected spectatorlike behavior. Combination of C-Br stretch and symmetric C-H, (1,0,1), stretch does not show a cooperative effect. Contrary to the spectator mode concept, energy originally stored in the C-H stretching mode is by no means conserved, but almost completely released in other modes of the reaction products. Products are most likely formed in states with a high degree of excitation in the new C-Cl bond, while the internal modes of the methyl group are less important. Reactants with combined umbrella/C-Br stretch excitation, (0, 1, 1), may yield products with two quanta in the umbrella mode.

  3. Non-linear stability bounds for a horizontal layer of a porous medium with an exothermic reaction on the lower boundary

    OpenAIRE

    Scott, Nicola L.

    2013-01-01

    We use the energy method to find regions of stability for a horizontal layer of a Darcy porous medium with an exothermic reaction on the lower layer. The results are compared to the linear instability results for this model found by Scott and Straughan [16]. It is shown that there is a region in which sub-critical instabilities may occur, but for small Lewis numbers, 0

  4. Kinetics and mechanism of the exothermic first-stage decomposition reaction of 1,3-bis(2,2,2-trinitroethyl)-1,3-diazacyclopentanone-2.

    Science.gov (United States)

    Rong-zu, Hu; De-suo, Yang; Sheng-li, Gao; San-ping, Chen; Hong-an, Zhao; Qi-zhen, Shi

    2003-08-29

    The thermal behavior, mechanism and kinetic parameters of the exothermic first-stage decomposition reaction of the title compound in a temperature-programmed mode have been investigated by means of DSC, TG-DTG and IR. The reaction mechanism was proposed. The kinetic model function in differential form, apparent activation energy (E(a)) and pre-exponential factor (A) of this reaction are (1-alpha)(2), 178.41 kJ mol(-1) and 10(17.06)s(-1), respectively. The critical temperature of thermal explosion of the compound is 184.99 degrees C. The values of DeltaS( not equal ), DeltaH( not equal ) and DeltaG( not equal ) of this reaction are 91.54 J mol(-1)K(-1), 176.86 kJ mol(-1) and 135.83 kJ mol(-1), respectively.

  5. TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

    Directory of Open Access Journals (Sweden)

    Marta Ziemnicka-Sylwester

    2013-05-01

    Full Text Available TiB2-based ceramic matrix composites (CMCs were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS was carried out for the highly exothermic “in situ” reaction of TiB2 formation and the “tailing” synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB2 vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB2:B4C molar ratio of 0.96, which corresponds to 40 vol% of TiB2 in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB2:B4C molar ratio of 2.16 or above. Finally B13C2 was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB2 grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure, were obtained for material containing 80 vol% of TiB2, fabricated using a graphite precursor of 2 μm.

  6. TiB2-Based Composites for Ultra-High-Temperature Devices, Fabricated by SHS, Combining Strong and Weak Exothermic Reactions

    Science.gov (United States)

    Ziemnicka-Sylwester, Marta

    2013-01-01

    TiB2-based ceramic matrix composites (CMCs) were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic “in situ” reaction of TiB2 formation and the “tailing” synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB2 vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB2:B4C molar ratio of 0.96, which corresponds to 40 vol% of TiB2 in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB2:B4C molar ratio of 2.16 or above. Finally B13C2 was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB2 grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure), were obtained for material containing 80 vol% of TiB2, fabricated using a graphite precursor of 2 μm. PMID:28809250

  7. Effects of Exothermic/Endothermic Chemical Reactions with Arrhenius Activation Energy on MHD Free Convection and Mass Transfer Flow in Presence of Thermal Radiation

    Directory of Open Access Journals (Sweden)

    Kh. Abdul Maleque

    2013-01-01

    Full Text Available A local similarity solution of unsteady MHD natural convection heat and mass transfer boundary layer flow past a flat porous plate within the presence of thermal radiation is investigated. The effects of exothermic and endothermic chemical reactions with Arrhenius activation energy on the velocity, temperature, and concentration are also studied in this paper. The governing partial differential equations are reduced to ordinary differential equations by introducing locally similarity transformation (Maleque (2010. Numerical solutions to the reduced nonlinear similarity equations are then obtained by adopting Runge-Kutta and shooting methods using the Nachtsheim-Swigert iteration technique. The results of the numerical solution are obtained for both steady and unsteady cases then presented graphically in the form of velocity, temperature, and concentration profiles. Comparison has been made for steady flow ( and shows excellent agreement with Bestman (1990, hence encouragement for the use of the present computations.

  8. Exothermic Behavior of Thermal Decomposition of Sodium Percarbonate: Kinetic Deconvolution of Successive Endothermic and Exothermic Processes.

    Science.gov (United States)

    Nakano, Masayoshi; Wada, Takeshi; Koga, Nobuyoshi

    2015-09-24

    This study focused on the kinetic modeling of the thermal decomposition of sodium percarbonate (SPC, sodium carbonate-hydrogen peroxide (2/3)). The reaction is characterized by apparently different kinetic profiles of mass-loss and exothermic behavior as recorded by thermogravimetry and differential scanning calorimetry, respectively. This phenomenon results from a combination of different kinetic features of the reaction involving two overlapping mass-loss steps controlled by the physico-geometry of the reaction and successive endothermic and exothermic processes caused by the detachment and decomposition of H2O2(g). For kinetic modeling, the overall reaction was initially separated into endothermic and exothermic processes using kinetic deconvolution analysis. Then, both of the endothermic and exothermic processes were further separated into two reaction steps accounting for the physico-geometrically controlled reaction that occurs in two steps. Kinetic modeling through kinetic deconvolution analysis clearly illustrates the appearance of the net exothermic effect is the result of a slight delay of the exothermic process to the endothermic process in each physico-geometrically controlled reaction step. This demonstrates that kinetic modeling attempted in this study is useful for interpreting the exothermic behavior of solid-state reactions such as the oxidative decomposition of solids and thermal decomposition of oxidizing agent.

  9. Safe design of cooled tubular reactors for exothermic, multiple reactions; parallel reactions—I: Development of criteria

    NARCIS (Netherlands)

    Westerterp, K.R.; Ptasiński, K.J.

    1984-01-01

    Previously reported design criteria for cooled tubular reactors are based on the prevention of reactor temperature run away and were developed for single reactions only. In this paper it is argued that such criteri a should be based on the reactor selectivity, from which eventually a maximum

  10. Development of a novel microreactor-based calorimeter for the study of fast exothermal reactions in liquid phase

    OpenAIRE

    Schneider, Marie-Agnès; Stoessel, Francis

    2005-01-01

    Following several tragic chemical accidents that have occurred in recent years, some directives concerning chemical process safety have been issued. The Seveso directive, for example, requires a precise description of the consequences of a possible chemical accident assuming a worst-case scenario. However, to build such scenarios and, hence, make chemical processes safe, profound knowledge of the kinetic and thermal parameters of the reactions in question is necessary. These parameters are us...

  11. Development of a novel microreactor-based calorimeter for the study of fast exothermal reactions in liquid phase

    OpenAIRE

    Schneider, Marie-Agnès

    2004-01-01

    Following several tragic chemical accidents that have occurred in recent years, some directives concerning chemical process safety have been issued. The Seveso directive, for example, requires a precise description of the consequences of a possible chemical accident assuming a worst-case scenario. However, to build such scenarios and, hence, make chemical processes safe, profound knowledge of the kinetic and thermal parameters of the reactions in question is necessary. These parameters are us...

  12. 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

    Science.gov (United States)

    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

  13. Controlling barrier penetration via exothermic iron oxidation.

    Science.gov (United States)

    Wood, Daniel G; Brown, Marc B; Jones, Stuart A

    2011-02-14

    Exothermic iron oxidation is an elegant means to generate heat, with the potential to modulate barrier penetration if reaction kinetics can be controlled. This aim of this study was to gain a fundamental understanding of how these temperature change kinetics influenced barrier diffusion rate. Lidocaine transport through a hydrophilic carboxymethyl cellulose (CMC) gel was compared using two rapid iron oxidation reactions initiated by water (ExoRap(50), T(max)-47.7 ± 0.6 °C, t(max)-3.3 ± 0.6 min, ExoRap(60), T(max)-60.4 ± 0.3 °C, t(max)-9.3 ± 0.6 min) and a slower reaction initiated by oxygen (ExoSl(45)T(max)-ca. 44 °C, t(max) ca. 240 min). Temperature change induced by the oxygen initiated reaction (ExoSl(45)) was almost double those initiated by water (over 4h), but lidocaine diffusion was approximately 4 times higher for the latter (ExoRap(50), 555.61 ± 22.04 μg/cm(2)/h; ExoRap(60), 663.1 ± 50.95 μg/cm(2)/h; compared to ExoSl(45), 159.36 ± 29.44 μg/cm(2)/h). The large influence of temperature change kinetics on lidocaine diffusion suggested that transport was heavily dependent on temperature induced structural changes of the barrier. CMC, like many polymers adsorbs more water when exposed to moderate increases in temperature and this appeared to be a critical determinant of lidocaine barrier diffusion rate. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Intensification of the electro slag process exothermic mixtures (fluxеs)

    OpenAIRE

    ВЛАСОВ А.Ф.; Макаренко, Н. О.; Чигарьов, Валерій Васильович

    2015-01-01

    It is established that an effective way to improve performance is to use the electro slag processes exothermic mixture (mechanical mixture scaling of aluminum powder and а standard flux) or flux exothermic (mechanical scaling mixtures, alloys, aluminum powder and a flux standard) in amounts sufficient for the exothermal reaction. Experimentally is defined the presence of the electrically conductive layer exothermic flux, allowing to carry out the electro slag process mono, bifilar or three-ph...

  15. Ignitable heterogeneous stratified structure for the propagation of an internal exothermic chemical reaction along an expanding wavefront and method of making same

    Science.gov (United States)

    Barbee, Jr., Troy W.; Weihs, Timothy

    1996-01-01

    A multilayer structure has a selectable, (i) propagating reaction front velocity V, (ii) reaction initiation temperature attained by application of external energy and (iii) amount of energy delivered by a reaction of alternating unreacted layers of the multilayer structure. Because V is selectable and controllable, a variety of different applications for the multilayer structures are possible, including but not limited to their use as ignitors, in joining applications, in fabrication of new materials, as smart materials and in medical applications and devices. The multilayer structure has a period D, and an energy release rate constant K. Two or more alternating unreacted layers are made of different materials and separated by reacted zones. The period D is equal to a sum of the widths of each single alternating reaction layer of a particular material, and also includes a sum of reacted zone widths, t.sub.i, in the period D. The multilayer structure has a selectable propagating reaction front velocity V, where V=K(1/D.sup.n).times.[1-(t.sub.i /D)] and n is about 0.8 to 1.2.

  16. Coupling of exothermic and endothermic hydrogen storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Kriston P.; Bowden, Mark E.; Karkamkar, Abhijeet J.; Houghton, Adrian Y.; Autrey, S. Thomas

    2016-08-01

    Chemical hydrogen storage (CHS) materials are a high-storage-density alternative to the gaseous compressed hydrogen currently used to provide hydrogen for fuel cell vehicles. One of the challenges of CHS materials is addressing the thermodynamic and kinetic barriers required to break the chemical bonds and release the hydrogen. Coupling CHS reactions that are endothermic and exothermic during the dehydrogenation can improve the system on-board energy efficiency and thermal control, making such materials viable. Acceptable coupling between reactions requires both thermodynamic and kinetics considerations. Models were developed to predict the reaction enthalpy and rate required to achieve high conversions for both reactions based on experimental measurements. These modeling results show that the efficiency of coupling of an exothermic and endothermic reaction is more sensitive the magnitude of the ratio of the exothermic and endothermic enthalpies than the ratio of the rates of the two steps. The modeling shows further that a slower rate of the endothermic step is desirable to permit sufficient heating of the reactor by the exothermic step. We look at two examples of a sequential and parallel reaction scheme and provide some of the first insight into the required temperature range to maximize the H2 release from 1,2-BN cyclohexane and indoline.

  17. Coupling of exothermic and endothermic hydrogen storage materials

    Science.gov (United States)

    Brooks, Kriston P.; Bowden, Mark E.; Karkamkar, Abhijeet J.; Houghton, Adrian Y.; Autrey, S. Thomas

    2016-08-01

    Chemical hydrogen storage (CHS) materials are a high-storage-density alternative to the gaseous compressed hydrogen currently used to provide hydrogen for fuel cell vehicles. One of the challenges of CHS materials is addressing the energy barriers required to break the chemical bonds and release the hydrogen. Coupling CHS reactions that are endothermic and exothermic during dehydrogenation can improve onboard energy efficiency and thermal control for the system, making such materials viable. Acceptable coupling between reactions requires both thermodynamic and kinetic considerations. In this work, models were developed to predict the reaction enthalpy and rate required to achieve high conversions for both reactions based on experimental measurements. Modeling results show that the coupling efficiency of exothermic and endothermic reactions is more sensitive to the ratio of the exothermic and endothermic enthalpies than to the ratio of the rates of the two steps. Modeling results also show that a slower endothermic step rate is desirable to permit sufficient heating of the reactor by the exothermic step. We look at two examples of a sequential and parallel reaction scheme and provide some of the first published insight into the required temperature range to maximize the hydrogen release from 1,2-BN cyclohexane and indoline.

  18. A robustness screen for the rapid assessment of chemical reactions.

    Science.gov (United States)

    Collins, Karl D; Glorius, Frank

    2013-07-01

    In contrast to the rapidity with which scientific information is published, the application of new knowledge often remains slow, and we believe this to be particularly true of newly developed synthetic organic chemistry methodology. Consequently, methods to assess and identify robust chemical reactions are desirable, and would directly facilitate the application of newly reported synthetic methodology to complex synthetic problems. Here, we describe a simple process for assessing the likely scope and limitations of a chemical reaction beyond the idealized reaction conditions initially reported. Using simple methods and common analytical techniques we demonstrate a rapid assessment of an established chemical reaction, and also propose a simplified analysis that may be reported alongside new synthetic methodology.

  19. Rapid Topochemical Modification of Layered Perovskites via Microwave Reactions.

    Science.gov (United States)

    Akbarian-Tefaghi, Sara; Teixeira Veiga, Elaine; Amand, Guillaume; Wiley, John B

    2016-02-15

    An effective microwave approach to the topochemical modification of different layered oxide perovskite hosts is presented where cation exchange, grafting, and intercalation reactions with acid, n-alkyl alcohols, and n-alkylamines, respectively, are successfully carried out. Microwave-assisted proton exchange reactions involving double- and triple-layered Dion-Jacobson and Ruddlesden-Popper perovskite family members, RbLnNb2O7 (Ln = La, Pr), KCa2Nb3O10, Li2CaTa2O7, and Na2La2Ti3O10, were found to be quite efficient, decreasing reaction times from several days to ≤3 h. Grafting and intercalation reactions involving double-layered perovskites were also quite rapid with full conversions occurring in as fast as an hour. Interestingly, triple-layered hosts were found to show different behavior; when complete intercalations were possible, grafting reactions were limited at best. Utilization of this rapid synthetic approach could help facilitate the fabrication of new organic-inorganic hybrids.

  20. Rapid electrochemiluminescence assays of polymerase chain reaction products.

    Science.gov (United States)

    Kenten, J H; Casadei, J; Link, J; Lupold, S; Willey, J; Powell, M; Rees, A; Massey, R

    1991-09-01

    We demonstrate the first use of an electrochemiluminescent (ECL) label, [4-(N-succimidyloxycarbonylpropyl)-4'-methyl-2,2'- bipyridine]ruthenium(II) dihexafluorophosphate (Origen label; IGEN Inc.), in DNA probe assays. This label allows rapid (less than 25 min) quantification and detection of polymerase chain reaction (PCR)-amplified products from oncogenes, viruses, and cloned genes. For the PCR, we used labeled oligonucleotide primers complementary to human papiloma virus and the Ha-ras oncogene. These samples were followed by ECL analysis or hybridization with specific, Origen-labeled oligonucleotide probes. These studies demonstrate the speed, specificity, and effectiveness of the new ECL labels, compared with 32P, for nucleic acid probe applications. We describe formats involving conventional methodologies and a new format that requires no wash step, allowing simple and rapid sample analysis. These rapid assays also reduce PCR contamination, by requiring less sample handling. Improvements in ECL detectability are currently under investigation for use in DNA probe assays without amplification.

  1. Metastable carbon phases from CF/sub 4/ reactions. Part I. Reactions with SiC and Si

    Energy Technology Data Exchange (ETDEWEB)

    Holcombe, C.E. Jr.; Condon, J.B.; Johnson, D.H.

    1978-09-01

    Reactions of CF/sub 4/ with ..beta..-SiC and Si powders were studied by thermal analysis techniques. Products were examined by x-ray and electron diffraction and electron microscopy. Two exotherms occur with ..beta..-SiC: at 874/sup 0/C, possibly from preferential reaction of the (111) planes; at 982/sup 0/C, presumably from rapid reaction on arbitrary planes. The primary product is amorphous carbon; however, graphite, carbon VI, or lonsdaleite single crystals also form. With Si powder, an exothermic reaction at 990/sup 0/C results from the formation of textured ..beta..-SiC.

  2. Rapid Hydrogen Shift Reactions in Acyl Peroxy Radicals

    DEFF Research Database (Denmark)

    Knap, Hasse Christian; Jørgensen, Solvejg

    2017-01-01

    We have used quantum mechanical chemical calculations (CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/aug-cc-pVTZ) to investigate the hydrogen shift (H-shift) reactions in acyl peroxy and hydroperoxy acyl peroxy radicals. We have focused on the H-shift reactions from a hydroperoxy group (OOH) (1,X-OOH H...

  3. Influence of curing agents on gelation and exotherm behaviour of an ...

    Indian Academy of Sciences (India)

    reduced gel-time and shortened exothermic reactions in applications such as liquid composite moulding processes. ... A nonlinear regression analysis of all gel- .... perature are profiled with the levels of cure ingredients dependence. 2. Materials. A commercially available medium reactive unsaturated polyester resin with a ...

  4. Influence of curing agents on gelation and exotherm behaviour of an ...

    Indian Academy of Sciences (India)

    A judicious choice of curing agents such as initiator and promoter and their ratio to the resin can avoid reduced gel-time and shortened exothermic reactions in applications such as liquid compositemoulding processes. In this study, effects of different ratio of initiator and promoter to the unsaturated polyester resin on curing ...

  5. Kinetic analysis of overlapping multistep thermal decomposition comprising exothermic and endothermic processes: thermolysis of ammonium dinitramide.

    Science.gov (United States)

    Muravyev, Nikita V; Koga, Nobuyoshi; Meerov, Dmitry B; Pivkina, Alla N

    2017-01-25

    This study focused on kinetic modeling of a specific type of multistep heterogeneous reaction comprising exothermic and endothermic reaction steps, as exemplified by the practical kinetic analysis of the experimental kinetic curves for the thermal decomposition of molten ammonium dinitramide (ADN). It is known that the thermal decomposition of ADN occurs as a consecutive two step mass-loss process comprising the decomposition of ADN and subsequent evaporation/decomposition of in situ generated ammonium nitrate. These reaction steps provide exothermic and endothermic contributions, respectively, to the overall thermal effect. The overall reaction process was deconvoluted into two reaction steps using simultaneously recorded thermogravimetry and differential scanning calorimetry (TG-DSC) curves by considering the different physical meanings of the kinetic data derived from TG and DSC by P value analysis. The kinetic data thus separated into exothermic and endothermic reaction steps were kinetically characterized using kinetic computation methods including isoconversional method, combined kinetic analysis, and master plot method. The overall kinetic behavior was reproduced as the sum of the kinetic equations for each reaction step considering the contributions to the rate data derived from TG and DSC. During reproduction of the kinetic behavior, the kinetic parameters and contributions of each reaction step were optimized using kinetic deconvolution analysis. As a result, the thermal decomposition of ADN was successfully modeled as partially overlapping exothermic and endothermic reaction steps. The logic of the kinetic modeling was critically examined, and the practical usefulness of phenomenological modeling for the thermal decomposition of ADN was illustrated to demonstrate the validity of the methodology and its applicability to similar complex reaction processes.

  6. Novel Direct Steelmaking by Combining Microwave, Electric Arc, and Exothermal Heating Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Xiaodi Huang; Dr. J. Y. Hwang

    2005-03-28

    Steel is a basic material broadly used by perhaps every industry and individual. It is critical to our nation's economy and national security. Unfortunately, the American steel industry is losing competitiveness in the world steel production field. There is an urgent need to develop the next generation of steelmaking technology for the American steel industry. Direct steelmaking through the combination of microwave, electric arc, and exothermal heating is a revolutionary change from current steelmaking technology. This technology can produce molten steel directly from a shippable agglomerate, consisting of iron oxide fines, powdered coal, and ground limestone. This technology is projected to eliminate many current intermediate steelmaking steps including coking, pellet sintering, blast furnace (BF) ironmaking, and basic oxygen furnace (BOF) steelmaking. This technology has the potential to (a) save up to 45% of the energy consumed by conventional steelmaking; (b) dramatically reduce the emission of CO{sub 2}, SO{sub 2}, NO{sub x}, VOCs, fine particulates, and air toxics; (c) substantially reduce waste and emission control costs; (d) greatly lower capital cost; and (e) considerably reduce steel production costs. This technology is based on the unique capability of microwaves to rapidly heat steelmaking raw materials to elevated temperature, then rapidly reduce iron oxides to metal by volumetric heating. Microwave heating, augmented with electric arc and exothermal reactions, is capable of producing molten steel. This technology has the components necessary to establish the ''future'' domestic steel industry as a technology leader with a strong economically competitive position in world markets. The project goals were to assess the utilization of a new steelmaking technology for its potential to achieve better overall energy efficiency, minimize pollutants and wastes, lower capital and operating costs, and increase the competitiveness of the

  7. Shock initiation of exothermic reactions in mechanically activated mixtures

    Science.gov (United States)

    Ananev, S. Yu; Dolgoborodov, A. Yu; Shiray, A. A.; Yankovsky, B. D.

    2016-11-01

    Experiments on initiation of chemical transformation in mechanically activated thermit mixtures are described. The initiation was produced by shock loading of compact porous thermit specimens in a semi-enclosed volume by explosion of an HE charge. Energy losses for shock wave passing through the thermit specimens and expansion rate of the field of chemical transformations in a free space were estimated.

  8. Probing fast ribozyme reactions under biological conditions with rapid quench-flow kinetics.

    Science.gov (United States)

    Bingaman, Jamie L; Messina, Kyle J; Bevilacqua, Philip C

    2017-05-01

    Reaction kinetics on the millisecond timescale pervade the protein and RNA fields. To study such reactions, investigators often perturb the system with abiological solution conditions or substrates in order to slow the rate to timescales accessible by hand mixing; however, such perturbations can change the rate-limiting step and obscure key folding and chemical steps that are found under biological conditions. Mechanical methods for collecting data on the millisecond timescale, which allow these perturbations to be avoided, have been developed over the last few decades. These methods are relatively simple and can be conducted on affordable and commercially available instruments. Here, we focus on using the rapid quench-flow technique to study the fast reaction kinetics of RNA enzymes, or ribozymes, which often react on the millisecond timescale under biological conditions. Rapid quench of ribozymes is completely parallel to the familiar hand-mixing approach, including the use of radiolabeled RNAs and fractionation of reactions on polyacrylamide gels. We provide tips on addressing and preventing common problems that can arise with the rapid-quench technique. Guidance is also offered on ensuring the ribozyme is properly folded and fast-reacting. We hope that this article will facilitate the broader use of rapid-quench instrumentation to study fast-reacting ribozymes under biological reaction conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Self-sustained high-temperature reactions : Initiation, propagation and synthesis

    NARCIS (Netherlands)

    Martinez Pacheco, M.

    2007-01-01

    Self-Propagating High-Temperature Synthesis (SHS), also called combustion synthesis is an exothermic and self-sustained reaction between the constituents, which has assumed significance for the production of ceramics and ceramic-metallic materials (cermets), because it is a very rapid processing

  10. Rapid quantitative detection of glucose content in glucose injection by reaction headspace gas chromatography.

    Science.gov (United States)

    Xie, Wei-Qi; Gong, Yi-Xian; Yu, Kong-Xian

    2017-10-20

    This work investigates an automated technique for rapid detecting the glucose content in glucose injection by reaction headspace gas chromatography (HS-GC). This method is based on the oxidation reaction of glucose in glucose injection with potassium dichromate. The carbon dioxide (CO 2 ) formed from the oxidation reaction can be quantitatively detected by GC. The results show that the relative standard deviation (RSD) of the present method was within 2.91%, and the measured glucose contents in glucose injection closely match those quantified by the reference method (relative differences glucose content in glucose injection related applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Aluminium dross-based insulating and exothermic materials for metallurgical industry

    Directory of Open Access Journals (Sweden)

    K. Stec

    2010-10-01

    Full Text Available In the conducted investigations, aluminium dross, i.e. solid waste formed in the production and recycling of aluminium, was used as one of the basic raw materials to obtain a material characterised by insulating and exothermic properties, applied to heat riser heads in the process of iron or steel casting. The product was obtained by filtrating the slurry. In the raw mix, aluminium dross played the role of a refractory filler and a source of metallic aluminium, taking part in exothermic reactions.The trials conducted in semi-technical conditions, using prototype riser head sleeves, proved their good quality and effectiveness in themetallurgical process, comparable to the currently applied imported sleeves.

  12. Why Combustions Are Always Exothermic, Yielding about 418 kJ per Mole of O[subscript 2

    Science.gov (United States)

    Schmidt-Rohr, Klaus

    2015-01-01

    The strongly exothermic nature of reactions between molecular oxygen and all organic molecules as well as many other substances is explained in simple, general terms. The double bond in O[subscript 2] is much weaker than other double bonds or pairs of single bonds, and therefore the formation of the stronger bonds in CO[subscript 2] and…

  13. More rapid polar ozone depletion through the reaction of HOCl with HCl on polar stratospheric clouds

    Science.gov (United States)

    Prather, Michael J.

    1992-01-01

    The direct reaction of HOCl with HCl is shown here to play a critical part in polar ozone loss. Observations of high levels of OClO and ClO in the springtime Antarctic stratosphere confirm that most of the available chlorine is in the form of ClO(x). But current photochemical models have difficulty converting HCl to ClO(x) rapidly enough in early spring to account fully for the observations. Here, a chemical model is used to show that the direct reaction of HOCl with HCl provides the missing mechanism. As alternative sources of nitrogen-containing oxidants have been converted in the late autumn to inactive HNO3 by known reactions on the sulfate layer aerosols, the reaction of HOCl with HCl on polar stratospheric clouds becomes the most important pathway for releasing that stratospheric chlorine which goes into polar night as HCl.

  14. HPLC method for rapidly following biodiesel fuel transesterification reaction progress using a core-shell column

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Samuel J.; Ott, Lisa S. [California State University, Chico, CA (United States)

    2012-07-15

    There are a wide and growing variety of feedstocks for biodiesel fuel. Most commonly, these feedstocks contain triglycerides which are transesterified into the fatty acid alkyl esters (FAAEs) which comprise biodiesel fuel. While the tranesterification reaction itself is simple, monitoring the reaction progress and reaction products is not. Gas chromatography-mass spectrometry is useful for assessing the FAAE products, but does not directly address either the tri-, di-, or monoglycerides present from incomplete transesterification or the free fatty acids which may also be present. Analysis of the biodiesel reaction mixture is complicated by the solubility and physical property differences among the components of the tranesterification reaction mixture. In this contribution, we present a simple, rapid HPLC method which allows for monitoring all of the main components in a biodiesel fuel transesterification reaction, with specific emphasis on the ability to monitor the reaction as a function of time. The utilization of a relatively new, core-shell stationary phase for the HPLC column allows for efficient separation of peaks with short elution times, saving both time and solvent. (orig.)

  15. Refolded scFv Antibody Fragment against Myoglobin Shows Rapid Reaction Kinetics

    Directory of Open Access Journals (Sweden)

    Hyung-Nam Song

    2014-12-01

    Full Text Available Myoglobin is one of the early biomarkers for acute myocardial infarction. Recently, we have screened an antibody with unique rapid reaction kinetics toward human myoglobin antigen. Antibodies with rapid reaction kinetics are thought to be an early IgG form produced during early stage of in vivo immunization. We produced a recombinant scFv fragment for the premature antibody from Escherichia coli using refolding technology. The scFv gene was constructed by connection of the VH–VL sequence with a (Gly4Ser3 linker. The scFv fragment without the pelB leader sequence was expressed at a high level, but the solubility was extremely low. A high concentration of 8 M urea was used for denaturation. The dilution refolding process in the presence of arginine and the redox reagents GSH and GSSH successfully produced a soluble scFv protein. The resultant refolded scFv protein showed association and dissociation values of 9.32 × 10−4 M−1·s−1 and 6.29 × 10−3 s−1, respectively, with an affinity value exceeding 107 M−1 (kon/koff, maintaining the original rapid reaction kinetics of the premature antibody. The refolded scFv could provide a platform for protein engineering for the clinical application for diagnosis of heart disease and the development of a continuous biosensor.

  16. Immediate hypersensitivity reaction associated with the rapid infusion of Crotalidae polyvalent immune Fab (ovine).

    Science.gov (United States)

    Holstege, Christopher P; Wu, Jeffrey; Baer, Alexander B

    2002-06-01

    A 16-year-old boy presented to the emergency department with rapidly progressing extremity pain, edema, and ecchymosis after envenomation by a copperhead. Crotalidae polyvalent immune Fab (ovine) (CroFab; FabAV) was infused. Six vials were placed in 250 mL of normal saline solution, and the infusion was gradually increased. Fifty minutes after beginning, the infusion was increased to 640 mL/h. Within minutes of the rate increase, the patient experienced full-body urticaria, facial edema, voice change, and tachycardia. The infusion was stopped. Hydroxyzine pamoate, famotidine, methylprednisolone, and a 1-L bolus of normal saline solution were administered intravenously. The symptoms abated, and the remaining FabAV was infused at a slower rate without return of this reaction. This immediate hypersensitivity reaction was most likely a rate-related anaphylactoid reaction that has not been previously reported with FabAV.[Holstege CP, Wu J, Baer AB. Immediate hypersensitivity reaction associated with the rapid infusion of Crotalidae polyvalent immune Fab (ovine). Ann Emerg Med. June 2002;39:677-679.

  17. Diffusion of the Reaction Boundary of Rapidly Interacting Macromolecules in Sedimentation Velocity

    Science.gov (United States)

    Schuck, Peter

    2010-01-01

    Abstract Sedimentation velocity analytical ultracentrifugation combines relatively high hydrodynamic resolution of macromolecular species with the ability to study macromolecular interactions, which has great potential for studying dynamically assembled multiprotein complexes. Complicated sedimentation boundary shapes appear in multicomponent mixtures when the timescale of the chemical reaction is short relative to the timescale of sedimentation. Although the Lamm partial differential equation rigorously predicts the evolution of concentration profiles for given reaction schemes and parameter sets, this approach is often not directly applicable to data analysis due to experimental and sample imperfections, and/or due to unknown reaction pathways. Recently, we have introduced the effective particle theory, which explains quantitatively and in a simple physical picture the sedimentation boundary patterns arising in the sedimentation of rapidly interacting systems. However, it does not address the diffusional spread of the reaction boundary from the cosedimentation of interacting macromolecules, which also has been of long-standing interest in the theory of sedimentation velocity analytical ultracentrifugation. Here, effective particle theory is exploited to approximate the concentration gradients during the sedimentation process, and to predict the overall, gradient-average diffusion coefficient of the reaction boundary. The analysis of the heterogeneity of the sedimentation and diffusion coefficients across the reaction boundary shows that both are relatively uniform. These results support the application of diffusion-deconvoluting sedimentation coefficient distributions c(s) to the analysis of rapidly interacting systems, and provide a framework for the quantitative interpretation of the diffusional broadening and the apparent molar mass values of the effective sedimenting particle in dynamically associating systems. PMID:20513419

  18. Effect of Al-B2O3-TiO2 Exothermic System on Performances of Fly Ash Glass/Ceramic Composite Coating

    Directory of Open Access Journals (Sweden)

    Yajun An

    2018-01-01

    Full Text Available Glass/ceramic composite coatings were prepared on 40Cr steel matrix by thermo-chemical reaction with fly ash and a small amount of SiO2, Al2O3, MgO, and albite as main raw materials. On this basis, adding 10% Al-TiO2-B2O3 exothermic system, the morphology, phase, thermal shock resistance, and corrosion resistance of the coating were tested, and the influence of exothermic system on the structure and properties of the composite coating was studied. The experimental results show that the addition of exothermic system can promote the formation of NaB15, TiB2, Na2B4O7, Ca2Al2SiO7, and other new phases by thermo-chemical reaction; when compared to the composite coating without addition of exothermic system, combined with a good interface, higher compactness, and lower porosity. The highest micro hardness can be reached 725HV0.1. The number of thermal shock from 700 °C to room temperature can reach more than 50 times; acid, salt, oil immersion corrosion test, composite coating with exothermic system relative to the matrix increased by 27.40 times, 3.97 times, and 1.88 times, respectively. The overall performance is better than that of the composite coating without exothermic system.

  19. A rapid electrochemical biosensor based on an AC electrokinetics enhanced immuno-reaction.

    Science.gov (United States)

    Cheng, I-Fang; Yang, Hsiao-Lan; Chung, Cheng-Che; Chang, Hsien-Chang

    2013-08-21

    Fluorescent labelling and chromogenic reactions that are commonly used in conventional immunoassays typically utilize diffusion dominated transport of analytes, which is limited by slow reaction rates and long detection times. By integrating alternating current (AC) electrokinetics and electrochemical impedance spectroscopy (EIS), we construct an immunochip for rapid, sensitive, and label-free detection. AC electroosmosis (ACEO) and positive dielectrophoresis (DEP), induced by a biased AC electric field, can rapidly convect and trap the analyte onto an EIS working electrode within a few minutes. This allows the change of electron-transfer resistance (ΔRet) caused by the antibody-antigen (IgG-protein A) binding to be measured and quantified in real time. The measured impedance change achieves a plateau after electrokinetic concentration for only 90 s, and the detection limit is able to reach 200 pg ml⁻¹. Compared to the conventional incubation method, the electrokinetics-enhanced method is approximately 100 times faster in its reaction time, and the detection limit is reduced by 30 times. The ΔRet of the positive response is two orders of magnitude higher than the negative control, demonstrating excellent specificity for practical applications.

  20. Melt-driven mechanochemical phase transformations in moderately exothermic powder mixtures.

    Science.gov (United States)

    Humphry-Baker, Samuel A; Garroni, Sebastiano; Delogu, Francesco; Schuh, Christopher A

    2016-12-01

    Usually, mechanochemical reactions between solid phases are either gradual (by deformation-induced mixing), or self-propagating (by exothermic chemical reaction). Here, by means of a systematic kinetic analysis of the Bi-Te system reacting to Bi2Te3, we establish a third possibility: if one or more of the powder reactants has a low melting point and low thermal effusivity, it is possible that local melting can occur from deformation-induced heating. The presence of hot liquid then triggers chemical mixing locally. The molten events are constrained to individual particles, making them distinct from self-propagating reactions, and occur much faster than conventional gradual reactions. We show that the mechanism is applicable to a broad variety of materials systems, many of which have important functional properties. This mechanistic picture offers a new perspective as compared to conventional, gradual mechanochemical synthesis, where thermal effects are generally ignored.

  1. Rapid Removal of Tetrabromobisphenol A by Ozonation in Water: Oxidation Products, Reaction Pathways and Toxicity Assessment

    Science.gov (United States)

    Wang, Xinghao; Huang, Qingguo; Lu, Junhe; Wang, Liansheng; Wang, Zunyao

    2015-01-01

    Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants and has attracted more and more attention. In this work, the parent TBBPA with an initial concentration of 100 mg/L was completely removed after 6 min of ozonation at pH 8.0, and alkaline conditions favored a more rapid removal than acidic and neutral conditions. The presence of typical anions and humic acid did not significantly affect the degradation of TBBPA. The quenching test using isopropanol indicated that direct ozone oxidation played a dominant role during this process. Seventeen reaction intermediates and products were identified using an electrospray time-of-flight mass spectrometer. Notably, the generation of 2,4,6-tribromophenol was first observed in the degradation process of TBBPA. The evolution of reaction products showed that ozonation is an efficient treatment for removal of both TBBPA and intermediates. Sequential transformation of organic bromine to bromide and bromate was confirmed by ion chromatography analysis. Two primary reaction pathways that involve cleavage of central carbon atom and benzene ring cleavage concomitant with debromination were thus proposed and further justified by calculations of frontier electron densities. Furthermore, the total organic carbon data suggested a low mineralization rate, even after the complete removal of TBBPA. Meanwhile, the acute aqueous toxicity of reaction solutions to Photobacterium Phosphoreum and Daphnia magna was rapidly decreased during ozonation. In addition, no obvious difference in the attenuation of TBBPA was found by ozone oxidation using different water matrices, and the effectiveness in natural waters further demonstrates that ozonation can be adopted as a promising technique to treat TBBPA-contaminated waters. PMID:26430733

  2. Rapid Removal of Tetrabromobisphenol A by Ozonation in Water: Oxidation Products, Reaction Pathways and Toxicity Assessment.

    Directory of Open Access Journals (Sweden)

    Ruijuan Qu

    Full Text Available Tetrabromobisphenol A (TBBPA is one of the most widely used brominated flame retardants and has attracted more and more attention. In this work, the parent TBBPA with an initial concentration of 100 mg/L was completely removed after 6 min of ozonation at pH 8.0, and alkaline conditions favored a more rapid removal than acidic and neutral conditions. The presence of typical anions and humic acid did not significantly affect the degradation of TBBPA. The quenching test using isopropanol indicated that direct ozone oxidation played a dominant role during this process. Seventeen reaction intermediates and products were identified using an electrospray time-of-flight mass spectrometer. Notably, the generation of 2,4,6-tribromophenol was first observed in the degradation process of TBBPA. The evolution of reaction products showed that ozonation is an efficient treatment for removal of both TBBPA and intermediates. Sequential transformation of organic bromine to bromide and bromate was confirmed by ion chromatography analysis. Two primary reaction pathways that involve cleavage of central carbon atom and benzene ring cleavage concomitant with debromination were thus proposed and further justified by calculations of frontier electron densities. Furthermore, the total organic carbon data suggested a low mineralization rate, even after the complete removal of TBBPA. Meanwhile, the acute aqueous toxicity of reaction solutions to Photobacterium Phosphoreum and Daphnia magna was rapidly decreased during ozonation. In addition, no obvious difference in the attenuation of TBBPA was found by ozone oxidation using different water matrices, and the effectiveness in natural waters further demonstrates that ozonation can be adopted as a promising technique to treat TBBPA-contaminated waters.

  3. Direct detection of exothermic dark matter with light mediator

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Chao-Qiang [Chongqing University of Posts & Telecommunications,Chongqing, 400065 (China); Department of Physics, National Tsing Hua University,Hsinchu, Taiwan (China); Physics Division, National Center for Theoretical Sciences,Hsinchu, Taiwan (China); Huang, Da; Lee, Chun-Hao [Department of Physics, National Tsing Hua University,Hsinchu, Taiwan (China); Wang, Qing [Department of Physics, Tsinghua University,Beijing, 100084 (China); Collaborative Innovation Center of Quantum Matter,Beijing, 100084 (China)

    2016-08-05

    We study the dark matter (DM) direct detection for the models with the effects of the isospin-violating couplings, exothermic scatterings, and/or the lightness of the mediator, proposed to relax the tension between the CDMS-Si signals and null experiments. In the light of the new updates of the LUX and CDMSlite data, we find that many of the previous proposals are now ruled out, including the Ge-phobic exothermic DM model and the Xe-phobic DM one with a light mediator. We also examine the exothermic DM models with a light mediator but without the isospin violation, and we are unable to identify any available parameter space that could simultaneously satisfy all the experiments. The only models that can partially relax the inconsistencies are the Xe-phobic exothermic DM models with or without a light mediator. But even in this case, a large portion of the CDMS-Si regions of interest has been constrained by the LUX and SuperCDMS data.

  4. A temperature programmed reaction/single-photon ionization time-of-flight mass spectrometry system for rapid investigation of gas-solid heterogeneous catalytic reactions under realistic reaction conditions

    NARCIS (Netherlands)

    He, Songbo; Cui, Huapeng; Lai, Yulong; Sun, Chenglin; Luo, Sha; Li, Haiyang; Seshan, Kulathuiyer

    2015-01-01

    A Temperature-Programmed Reaction (TPRn)/Single-Photon Ionization Time-of-Flight Mass Spectrometry (SPI-TOF-MS) system is described. The TPRn/SPI-TOF-MS system allows rapid characterization of heterogeneous catalytic reactions under realistic reaction conditions and at the same time allows for the

  5. Rapid detection of microbial DNA by a novel isothermal genome exponential amplification reaction (GEAR) assay.

    Science.gov (United States)

    Prithiviraj, Jothikumar; Hill, Vincent; Jothikumar, Narayanan

    2012-04-20

    In this study we report the development of a simple target-specific isothermal nucleic acid amplification technique, termed genome exponential amplification reaction (GEAR). Escherichia coli was selected as the microbial target to demonstrate the GEAR technique as a proof of concept. The GEAR technique uses a set of four primers; in the present study these primers targeted 5 regions on the 16S rRNA gene of E. coli. The outer forward and reverse Tab primer sequences are complementary to each other at their 5' end, whereas their 3' end sequences are complementary to their respective target nucleic acid sequences. The GEAR assay was performed at a constant temperature 60 °C and monitored continuously in a real-time PCR instrument in the presence of an intercalating dye (SYTO 9). The GEAR assay enabled amplification of as few as one colony forming units of E. coli per reaction within 30 min. We also evaluated the GEAR assay for rapid identification of bacterial colonies cultured on agar media directly in the reaction without DNA extraction. Cells from E. coli colonies were picked and added directly to GEAR assay mastermix without prior DNA extraction. DNA in the cells could be amplified, yielding positive results within 15 min. Published by Elsevier Inc.

  6. Empathy, emotional contagion, and rapid facial reactions to angry and happy facial expressions.

    Science.gov (United States)

    Dimberg, Ulf; Thunberg, Monika

    2012-12-01

    The aim was to explore whether emotional empathy is related to the capacity to react with rapid facial reactions to facial expressions of emotion, and if emotional empathy is related to the ability to experience a similar emotion as expressed by another person. People high or low in emotional empathy were exposed to pictures of happy and angry faces while their facial electromyography from the zygomaticus major and corrugator supercilii muscle regions was detected. High empathy participants rapidly reacted with larger zygomatic muscle activity to happy as compared with angry faces as early as after 500 ms after stimulus onset, and with larger corrugator muscle activity to angry than to happy faces after 500 ms. Accordingly, this group also reacted with a corresponding experience of emotion. The low empathy participants, in contrast, did not differentiate between the happy and angry stimuli with either facial muscles or in their self experience of emotion. The findings are related to the facial feedback hypothesis and the results are interpreted as support for the hypothesis that rapid and automatically evoked facial mimicry may be one important mechanism for emotional and empathic contagion to occur. © 2012 The Institute of Psychology, Chinese Academy of Sciences and Blackwell Publishing Asia Pty Ltd.

  7. Rapid disease progression in human immunodeficiency virus type 1-infected individuals with adverse reactions to trimethoprim-sulfamethoxazole prophylaxis

    NARCIS (Netherlands)

    Veenstra, J.; Veugelers, P. J.; Keet, I. P.; van der Ven, A. J. A. M.; Miedema, F.; Lange, J. M.; Coutinho, R. A.

    1997-01-01

    We studied the relation between the occurrence of adverse reactions to trimethoprim-sulfamethoxazole (TMP-SMZ) prophylaxis and the subsequent course of human immunodeficiency virus (HIV) infection in a cohort of homosexual men. Adverse reactions to TMP-SMZ were associated with a more rapid

  8. Nano-Phase Powder Based Exothermic Braze Repair Technology For RCC Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — MRi is proposing, with its partner, Exotherm Corp (Camden, NJ) to demonstrate the feasibility of using exothermic brazing to join RCC (or C:SiC) composites to itself...

  9. The formation of ice mantles on interstellar grains revisited--the effect of exothermicity.

    Science.gov (United States)

    Lamberts, T; de Vries, X; Cuppen, H M

    2014-01-01

    Modelling of grain surface chemistry generally deals with the simulation of rare events. Usually deterministic methods or statistical approaches such as the kinetic Monte Carlo technique are applied for these simulations. All assume that the surface processes are memoryless, the Markov chain assumption, and usually also that their rates are time independent. In this paper we investigate surface reactions for which these assumptions are not valid, and discuss what the effect is on the formation of water on interstellar grains. We will particularly focus on the formation of two OH radicals by the reaction H + HO2. Two reaction products are formed in this exothermic reaction and the resulting momentum gained causes them to move away from each other. What makes this reaction special is that the two products can undergo a follow-up reaction to form H2O2. Experimentally, OH has been observed, which means that the follow-up reaction does not proceed with 100% efficiency, even though the two OH radicals are formed in each other's vicinity in the same reaction. This can be explained by a combined effect of the directionality of the OH radical movement together with energy dissipation. Both effects are constrained by comparison with experiments, and the resulting parametrised mechanism is applied to simulations of the formation of water ice under interstellar conditions.

  10. Fabrication of Polymerase Chain Reaction Plastic Lab-on-a-Chip Device for Rapid Molecular Diagnoses.

    Science.gov (United States)

    Trinh, Kieu The Loan; Zhang, Hainan; Kang, Dong-Jin; Kahng, Sung-Hyun; Tall, Ben D; Lee, Nae Yoon

    2016-05-01

    We aim to fabricate a thermoplastic poly(methylmethacrylate) (PMMA) Lab-on-a-Chip device to perform continuous- flow polymerase chain reactions (PCRs) for rapid molecular detection of foodborne pathogen bacteria. A miniaturized plastic device was fabricated by utilizing PMMA substrates mediated by poly(dimethylsiloxane) interfacial coating, enabling bonding under mild conditions, and thus avoiding the deformation or collapse of microchannels. Surface characterizations were carried out and bond strength was measured. The feasibility of the Lab-on-a-Chip device for performing on-chip PCR utilizing a lab-made, portable dual heater was evaluated. The results were compared with those obtained using a commercially available thermal cycler. A PMMA Lab-on-a-Chip device was designed and fabricated for conducting PCR using foodborne pathogens as sample targets. A robust bond was established between the PMMA substrates, which is essential for performing miniaturized PCR on plastic. The feasibility of on-chip PCR was evaluated using Escherichia coli O157:H7 and Cronobacter condimenti, two worldwide foodborne pathogens, and the target amplicons were successfully amplified within 25 minutes. In this study, we present a novel design of a low-cost and high-throughput thermoplastic PMMA Lab-on-a-Chip device for conducting microscale PCR, and we enable rapid molecular diagnoses of two important foodborne pathogens in minute resolution using this device. In this regard, the introduced highly portable system design has the potential to enable PCR investigations of many diseases quickly and accurately.

  11. Quantitative methylene blue decolourisation assays as rapid screening tools for assessing the efficiency of catalytic reactions.

    Science.gov (United States)

    Kruid, Jan; Fogel, Ronen; Limson, Janice Leigh

    2017-05-01

    Identifying the most efficient oxidation process to achieve maximum removal of a target pollutant compound forms the subject of much research. There exists a need to develop rapid screening tools to support research in this area. In this work we report on the development of a quantitative assay as a means for identifying catalysts capable of decolourising methylene blue through the generation of oxidising species from hydrogen peroxide. Here, a previously described methylene blue test strip method was repurposed as a quantitative, aqueous-based spectrophotometric assay. From amongst a selection of metal salts and metallophthalocyanine complexes, monitoring of the decolourisation of the cationic dye methylene blue (via Fenton-like and non-Fenton oxidation reactions) by the assay identified the following to be suitable oxidation catalysts: CuSO 4 (a Fenton-like catalyst), iron(II)phthalocyanine (a non-Fenton oxidation catalyst), as well as manganese(II) phthalocyanine. The applicability of the method was examined for the removal of bisphenol A (BPA), as measured by HPLC, during parallel oxidation experiments. The order of catalytic activity was identified as FePc > MnPc > CuSO 4 for both BPA and MB. The quantitative MB decolourisation assay may offer a rapid method for screening a wide range of potential catalysts for oxidation processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Reverse transcription genome exponential amplification reaction assay for rapid and universal detection of human rhinoviruses.

    Science.gov (United States)

    Guan, Li; Zhao, Lin-Qing; Zhou, Hang-Yu; Nie, Kai; Li, Xin-Na; Zhang, Dan; Song, Juan; Qian, Yuan; Ma, Xue-Jun

    2016-07-01

    Human rhinoviruses (HRVs) have long been recognized as the cause of more than one-half of acute viral upper respiratory illnesses, and they are associated with more-serious diseases in children, such as asthma, acute otitis media and pneumonia. A rapid and universal test for of HRV infection is in high demand. In this study, a reverse transcription genome exponential amplification reaction (RT-GEAR) assay targeting the HRV 5' untranslated region (UTR) was developed for pan-HRV detection. The reaction was performed in a single tube in one step at 65 °C for 60 min using a real-time fluorometer (Genie(®)II; Optigene). The RT-GEAR assay showed no cross-reactivity with common human enteroviruses, including HEV71, CVA16, CVA6, CVA10, CVA24, CVB5, Echo30, and PV1-3 or with other common respiratory viruses including FluA H3, FluB, PIV1-4, ADV3, RSVA, RSVB and HMPV. With in vitro-transcribed RNA containing the amplified regions of HRV-A60, HRV-B06 and HRV-C07 as templates, the sensitivity of the RT-GEAR assay was 5, 50 and 5 copies/reaction, respectively. Experiments to evaluate the clinical performance of the RT-GEAR assay were also carried out with a panel of 143 previously verified samples, and the results were compared with those obtained using a published semi-nested PCR assay followed by sequencing. The tested panel comprised 91 HRV-negative samples and 52 HRV-positive samples (18 HRV-A-positive samples, 3 HRV-B-positive samples and 31 HRV-C-positive samples). The sensitivity and specificity of the pan-HRVs RT-GEAR assay was 98.08 % and 100 %, respectively. The kappa correlation between the two methods was 0.985. The RT-GEAR assay based on a portable Genie(®)II fluorometer is a sensitive, specific and rapid assay for the universal detection of HRV infection.

  13. Instrument-free exothermic heating with phase change temperature control for paper microfluidic devices

    Science.gov (United States)

    Singleton, Jered; Zentner, Chris; Buser, Josh; Yager, Paul; LaBarre, Paul; Weigl, Bernhard H.

    2013-03-01

    Many infectious diseases, as well as some cancers, that affect global health are most accurately diagnosed through nucleic acid amplification and detection. There is a great need to simplify nucleic acid-based assay systems for use in global health in low-resource settings as well as in settings that do not have convenient access to laboratory staff and equipment such as doctors' offices and home care settings. In developing countries, unreliable electric power, inadequate supply chains, and lack of maintenance for complex diagnostic instruments are all common infrastructure shortfalls. Many elements of instrument-free, disposable, nucleic acid amplification assays have been demonstrated in recent years. However, the problem of instrument-free,1 low-cost, temperature-controlled chemical heating remains unsolved. In this paper we present the current status and results of work towards developing disposable, low-cost, temperature-controlled heaters designed to support isothermal nucleic acid amplification assays that are integrated with a two-dimensional paper network. Our approach utilizes the heat generated through exothermic chemical reactions and controls the heat through use of engineered phase change materials to enable sustained temperatures required for nucleic acid amplification. By selecting appropriate exothermic and phase change materials, temperatures can be controlled over a wide range, suitable for various isothermal amplification methods, and maintained for over an hour at an accuracy of +/- 1°C.

  14. Osteoconductive Amine-Functionalized Graphene-Poly(methyl methacrylate) Bone Cement Composite with Controlled Exothermic Polymerization.

    Science.gov (United States)

    Sharma, Rakesh; Kapusetti, Govinda; Bhong, Sayali Yashwant; Roy, Partha; Singh, Santosh Kumar; Singh, Shikha; Balavigneswaran, Chelladurai Karthikeyan; Mahato, Kaushal Kumar; Ray, Biswajit; Maiti, Pralay; Misra, Nira

    2017-09-20

    Bone cement has found extensive usage in joint arthroplasty over the last 50 years; still, the development of bone cement with essential properties such as high fatigue resistance, lower exothermic temperature, and bioactivity has been an unsolved problem. In our present work, we have addressed all of the mentioned shortcomings of bone cement by reinforcing it with graphene (GR), graphene oxide (GO), and surface-modified amino graphene (AG) fillers. These nanocomposites have shown hypsochromic shifts, suggesting strong interactions between the filler material and the polymer matrix. AG-based nanohybrids have shown greater osteointegration and lower cytotoxicity compared to other nanohybrids as well as pristine bone cement. They have also reduced oxidative stress on cells, resulting in calcification within 20 days of the implantation of nanohybrids into the rabbits. They have significantly reduced the exothermic curing temperature to body temperature and increased the setting time to facilitate practitioners, suggesting that reaction temperature and settling time can be dynamically controlled by varying the concentration of the filler. Thermal stability and enhanced mechanical properties have been achieved in nanohybrids vis-à-vis pure bone cement. Thus, this newly developed nanocomposite can create natural bonding with bone tissues for improved bioactivity, longer sustainability, and better strength in the prosthesis.

  15. Fabrication of Polymerase Chain Reaction Plastic Lab-on-a-Chip Device for Rapid Molecular Diagnoses

    Science.gov (United States)

    2016-01-01

    Purpose: We aim to fabricate a thermoplastic poly(methylmethacrylate) (PMMA) Lab-on-a-Chip device to perform continuous- flow polymerase chain reactions (PCRs) for rapid molecular detection of foodborne pathogen bacteria. Methods: A miniaturized plastic device was fabricated by utilizing PMMA substrates mediated by poly(dimethylsiloxane) interfacial coating, enabling bonding under mild conditions, and thus avoiding the deformation or collapse of microchannels. Surface characterizations were carried out and bond strength was measured. The feasibility of the Lab-on-a-Chip device for performing on-chip PCR utilizing a lab-made, portable dual heater was evaluated. The results were compared with those obtained using a commercially available thermal cycler. Results: A PMMA Lab-on-a-Chip device was designed and fabricated for conducting PCR using foodborne pathogens as sample targets. A robust bond was established between the PMMA substrates, which is essential for performing miniaturized PCR on plastic. The feasibility of on-chip PCR was evaluated using Escherichia coli O157:H7 and Cronobacter condimenti, two worldwide foodborne pathogens, and the target amplicons were successfully amplified within 25 minutes. Conclusions: In this study, we present a novel design of a low-cost and high-throughput thermoplastic PMMA Lab-on-a-Chip device for conducting microscale PCR, and we enable rapid molecular diagnoses of two important foodborne pathogens in minute resolution using this device. In this regard, the introduced highly portable system design has the potential to enable PCR investigations of many diseases quickly and accurately. PMID:27230459

  16. Topical perfluorodecalin resolves immediate whitening reactions and allows rapid effective multiple pass treatment of tattoos.

    Science.gov (United States)

    Reddy, Kavitha K; Brauer, Jeremy A; Anolik, Robert; Bernstein, Leonard; Brightman, Lori; Hale, Elizabeth; Karen, Julie; Weiss, Elliot; Geronemus, Roy G

    2013-02-01

    Laser tattoo removal using multiple passes per session, with each pass delivered after spontaneous resolution of whitening, improves tattoo fading in a 60-minute treatment time. Our objective was to evaluate the safety and efficacy of topical perfluorodecalin (PFD) in facilitating rapid effective multiple-pass tattoo removal. In a randomized, controlled study using Q-switched ruby or Nd:YAG laser, 22 previously treated tattoos were treated with 3 passes using PFD to resolve whitening after each pass ("R0 method"). In previously untreated symmetric tattoos, seven were treated over half of the tattoo with the R20 method, and the opposite half with 4 passes using PFD (R0 method); two were treated over half with a single pass and the opposite half with 4 passes using PFD (R0 method); and six treated over half with a single pass followed by PFD and the opposite half with a single pass alone. Blinded dermatologists rated tattoo fading at 1-3 months. Optical coherence tomography (OCT) imaging of whitening was performed in two tattoos. Topical PFD clinically resolved immediate whitening reactions within a mean 5 seconds (range 3-10 seconds). Tattoos treated with the R0 method demonstrated excellent fading in an average total treatment time of 5 minutes. Tattoo areas treated with the R0 method demonstrated equal fading compared to the R20 method, and improved fading compared to a single pass method. OCT imaging of whitening demonstrated epidermal and dermal hyper-reflective "bubbles" that dissipated until absent at 9-10 minutes after PFD application, and at 20 minutes without intervention. Multiple-pass tattoo removal using PFD to deliver rapid sequential passes (R0 method) appears equally effective as the R20 method, in a total treatment time averaging 5 minutes, and more effective than single pass treatment. OCT-visualized whitening-associated "bubbles," upon treatment with PFD, resolve twice as rapidly as spontaneous resolution. Copyright © 2012 Wiley

  17. Hedonic reactivity to visual and olfactory cues: rapid facial electromyographic reactions are altered in anorexia nervosa.

    Science.gov (United States)

    Soussignan, Robert; Schaal, Benoist; Rigaud, Daniel; Royet, Jean-Pierre; Jiang, Tao

    2011-03-01

    Though it has been suggested that hedonic processing is altered in anorexia nervosa (AN), few studies have used objective measures to assess affective processes in this eating disorder. Accordingly, we investigated facial electromyographic, autonomic and subjective reactivity to the smell and sight of food and non-food stimuli, and assessed more particularly rapid facial reactions reflecting automatic processing of pleasantness. AN and healthy control (HC) women were exposed, before and after a standardized lunch, to pictures and odorants of foods differing in energy density, as well as to non-food sensory cues. Whereas the temporal profile of zygomatic activity in AN patients was typified by a fast drop to sensory cues within the 1000 ms following stimulus onset, HC showed a larger EMG reactivity to pictures in a 800-1000 ms time window. In contrast, pleasantness ratings discriminated the two groups only for high energy density food cues suggesting a partial dissociation between objective and subjective measures of hedonic processes in AN patients. The findings suggest that the automatic processing of pleasantness might be altered in AN, with the sensitivity to reward being modulated by controlled processes. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Detecting Malaria Hotspots: A Comparison of Rapid Diagnostic Test, Microscopy, and Polymerase Chain Reaction.

    Science.gov (United States)

    Mogeni, Polycarp; Williams, Thomas N; Omedo, Irene; Kimani, Domtila; Ngoi, Joyce M; Mwacharo, Jedida; Morter, Richard; Nyundo, Christopher; Wambua, Juliana; Nyangweso, George; Kapulu, Melissa; Fegan, Gregory; Bejon, Philip

    2017-11-27

    Malaria control strategies need to respond to geographical hotspots of transmission. Detection of hotspots depends on the sensitivity of the diagnostic tool used. We conducted cross-sectional surveys in 3 sites within Kilifi County, Kenya, that had variable transmission intensities. Rapid diagnostic test (RDT), microscopy, and polymerase chain reaction (PCR) were used to detect asymptomatic parasitemia, and hotspots were detected using the spatial scan statistic. Eight thousand five hundred eighty-one study participants were surveyed in 3 sites. There were statistically significant malaria hotspots by RDT, microscopy, and PCR for all sites except by microscopy in 1 low transmission site. Pooled data analysis of hotspots by PCR overlapped with hotspots by microscopy at a moderate setting but not at 2 lower transmission settings. However, variations in degree of overlap were noted when data were analyzed by year. Hotspots by RDT were predictive of PCR/microscopy at the moderate setting, but not at the 2 low transmission settings. We observed long-term stability of hotspots by PCR and microscopy but not RDT. Malaria control programs may consider PCR testing to guide asymptomatic malaria hotspot detection once the prevalence of infection falls.

  19. Rapid detection of Listeria monocytogenes in food by polymerase chain reaction.

    Science.gov (United States)

    Ennaji, H; Timinouni, M; Ennaji, M M; Ait m'hand, R; Hassar, M; Cohen, N

    2009-02-25

    The standard conventional methods for the detection of Listeria monocytogenes in foods require high time 7 to 10 days to give ready results. To dissolve this problem we have evaluate a short method using Polymerase Chain Reaction (PCR) to analyze food samples. In parallel with this study, a comparison was made between PCR amplification from templates directly prepared from food and the official standard ISO procedure 11290-1. In this study we have used a Half Frazer broth as an enrichment medium; there were positive results of PCR detection of L. monocytogenes in different food sample analyzed (milk, cheese and meat) with approximately 1.5 10(1) Colony Forming Units /25 g in less than 36 h. This PCR procedure has proved to be rapid and sensitive method suitable for the routine analysis; firstly, because this assay required just a short pre-enrichment step before PCR. Secondly, this procedure is very simple and time-saving; it could take less than one working day to obtain results if initial microbiological load was very important.

  20. Improved Multiplex Polymerase Chain Reaction for Rapid Staphylococcus Aureus Detection in Meat and Milk Matrices

    Directory of Open Access Journals (Sweden)

    Šramková Zuzana

    2016-06-01

    Full Text Available Staphylococcal food poisoning represents one of the most frequently occurring intoxications, caused by staphylococcal enterotoxins (SE-s and staphylococcal enterotoxin-like proteins (SEl-s. Therefore, there is a need for rapid, sensitive and specific detection method for this human pathogen and its toxin genes in food matrices. The present work is focused on Staphylococcus aureus detection by a nonaplex polymerase chain reaction, which targets the 23S rRNA gene for identification of S. aureus at the species level, genes for classical SE-s (SEA, SEC, SED, new SE-s (SEH, SEI, SEl-s (SEK, SEL and tsst-1 gene (toxic shock syndrome toxin. Primers were properly designed to avoid undesirable interactions and to create a reliably identifiable profile of amplicons when visualized in agarose gel. According to obtained results, this approach is able to reach the detection sensitivity of 12 colony forming units from milk and meat matrices without prior culturing and DNA extraction.

  1. Extension of a Kinetic-Theory Approach for Computing Chemical-Reaction Rates to Reactions with Charged Particles

    Science.gov (United States)

    Liechty, Derek S.; Lewis, Mark J.

    2010-01-01

    Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties (i.e., no macroscopic reaction rate information) are extended to include reactions involving charged particles and electronic energy levels. The proposed extensions include ionization reactions, exothermic associative ionization reactions, endothermic and exothermic charge exchange reactions, and other exchange reactions involving ionized species. The extensions are shown to agree favorably with the measured Arrhenius rates for near-equilibrium conditions.

  2. Rapid Facial Reactions to Emotional Facial Expressions in Typically Developing Children and Children with Autism Spectrum Disorder

    Science.gov (United States)

    Beall, Paula M.; Moody, Eric J.; McIntosh, Daniel N.; Hepburn, Susan L.; Reed, Catherine L.

    2008-01-01

    Typical adults mimic facial expressions within 1000ms, but adults with autism spectrum disorder (ASD) do not. These rapid facial reactions (RFRs) are associated with the development of social-emotional abilities. Such interpersonal matching may be caused by motor mirroring or emotional responses. Using facial electromyography (EMG), this study…

  3. Rapid solid-state metathesis route to transition-metal doped titanias

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Nathaniel; Perera, Sujith; Gillan, Edward G., E-mail: edward-gillan@uiowa.edu

    2015-12-15

    Rapid solid-state metathesis (SSM) reactions are often short-lived highly exothermic reactions that yield a molten alkali halide salt that aids in product growth and crystallization. SSM reactions may also produce kinetically stabilized structures due to the short (seconds) reaction times. This report describes the investigation of rapid SSM reactions in the synthesis of transition-metal doped titanias (M–TiO{sub 2}). The dopant targeted compositions were ten mol percent and based on elemental analysis, many of the M–TiO{sub 2} samples were close to this targeted level. Based on surface analysis, some samples showed large enrichment in surface dopant content, particularly chromium and manganese doped samples. Due to the highly exothermic nature of these reactions, rutile structured TiO{sub 2} was observed in all cases. The M–TiO{sub 2} samples are visible colored and show magnetic and optical properties consistent with the dopant in an oxide environment. UV and visible photocatalytic experiments with these visibly colored rutile M–TiO{sub 2} powders showed that many of them are strongly absorbent for methylene blue dye and degrade the dye under both UV and visible light illumination. This work may open up SSM reactions as an alternate non-thermodynamic reaction strategy for dopant incorporation into a wide range of oxide and non-oxides.

  4. The Influence of Military Identity on Work Engagement and Burnout in the Norwegian Army Rapid Reaction Force

    OpenAIRE

    Johansen, Rino Bandlitz; Martinussen, Monica; Kvilvang, Nils

    2015-01-01

    The present study examined the influence of military identity on work engagement and burnout among members in the Norwegian Army Rapid Reaction Forces (RRF). Hierarchical regression analyses found work engagement to be predicted by military identity (positively so by professionalism, and negatively by individualism), with individualism also predicting burnout. This is the first study to examine the unique influence of military identity on burnout and engagement among operational army personne...

  5. Rapid Detection/pathotyping of Newcastle disease virus isolates in clinical samples using real time polymerase chain reaction assay

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Abdul Wajid, Muhammad Wasim, Tahir Yaqub, Shafqat F Rehmani, Tasra Bibi, Nadia Mukhtar, Javed Muhammad, Umar Bacha, Suliman Qadir Afridi, Muhammad Nauman Zahid, Zia u ddin, Muhammad Zubair Shabbir, Kamran Abbas & Muneer Ahmad ### Abstract In the present protocol we describe the real time reverse transcription polymerase chain reaction (rRT-PCR) assay for the rapid detection/pathotyping of Newcastle disease virus (NDV) isoaltes in clinical samples. Fusion gene and matrix gene...

  6. Interaction between the long-latency stretch reflex and voluntary electromyographic activity prior to a rapid voluntary motor reaction.

    Science.gov (United States)

    Day, B L; Rothwell, J C; Marsden, C D

    1983-06-27

    The size of the long-latency component of the stretch reflex has been examined in the time interval between a signal to move and the required rapid voluntary contraction of triceps and flexor pollicis longus in 8 normal subjects. Bilateral movements of the elbow and thumb were made following an auditory signal. In 50% of the trials a torque pulse was applied unilaterally in order to elicit a stretch reflex response in one arm. The voluntary response in the contralateral arm was uncorrupted by a stretch reflex response, so was used as an indicator of voluntary reaction time. Control experiments, using an electrical stimulus to the fingers rather than muscle stretch, verified that both arms reacted almost simultaneously to the auditory cue, even when the reaction time was shortened by the presence of a unilateral electrical stimulus. Similarly, an interposed muscle stretch stimulus considerably reduced the reaction time to the audio signal. Because of this, the start of the voluntary EMG response frequently 'over-lapped' the end of the long-latency stretch reflex. Failure to take this shortening of voluntary reaction time into consideration can lead to the erroneous conclusion that reflex gain is increased prior to a rapid movement. If the 'overlap' of EMG responses is accounted for, very little change in the size of the long-latency stretch reflex is evident prior to activation of the muscles responsible for the movement of either the elbow or the thumb.

  7. Rapid trace detection of triacetone triperoxide (TATP) by complexation reactions during desorption electrospray ionization.

    Science.gov (United States)

    Cotte-Rodríguez, Ismael; Chen, Hao; Cooks, R Graham

    2006-03-07

    Desorption electrospray ionization (DESI) mass spectrometry is used for rapid, specific and sensitive detection of trace amounts of the notorious explosive TATP present on ambient surfaces by alkali metal complexation in a simple spray technique.

  8. Development of a rapid and sensitive one-step reverse transcription-nested polymerase chain reaction in a single tube using the droplet-polymerase chain reaction machine.

    Science.gov (United States)

    Yamaguchi, Akemi; Matsuda, Kazuyuki; Sueki, Akane; Taira, Chiaki; Uehara, Masayuki; Saito, Yasunori; Honda, Takayuki

    2015-08-25

    Reverse transcription (RT)-nested polymerase chain reaction (PCR) is a time-consuming procedure because it has several handling steps and is associated with the risk of cross-contamination during each step. Therefore, a rapid and sensitive one-step RT-nested PCR was developed that could be performed in a single tube using a droplet-PCR machine. The K562 BCR-ABL mRNA-positive cell line as well as bone marrow aspirates from 5 patients with chronic myelogenous leukemia (CML) and 5 controls without CML were used. We evaluated one-step RT-nested PCR using the droplet-PCR machine. One-step RT-nested PCR performed in a single tube using the droplet-PCR machine enabled the detection of BCR-ABL mRNA within 40min, which was 10(3)-fold superior to conventional RT nested PCR using three steps in separate tubes. The sensitivity of the one-step RT-nested PCR was 0.001%, with sample reactivity comparable to that of the conventional assay. One-step RT-nested PCR was developed using the droplet-PCR machine, which enabled all reactions to be performed in a single tube accurately and rapidly and with high sensitivity. This one-step RT-nested PCR may be applicable to a wide spectrum of genetic tests in clinical laboratories. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Quantification and controllability study of minimally invasive exothermic chemo-ablation therapy for tumor ablation.

    Science.gov (United States)

    Liu, Ran; Huang, Yu; Liu, Jing

    2009-01-01

    The recently proposed exothermic chemical reaction based tumor hyperthermia method presented a new way of realizing truly minimally invasive treatment for tumor. This method utilizes heat generated from the reaction between acid and alkali solutions to allow for tumor ablation. Successful clinical implementation of this method requires a clearer understanding and quantification of the ablation area such that a more controllable operation can be made. A number of in-vitro and in-vivo experiments are designed to examine the features of thermal chemo-ablation therapy which include micro and macro characteristics of ablated tissue and temperature change during the ablation process. A Quantitative study on the relationship between velocity and ablation volume as well as a Graphical User Interface in Matlab for computerized ablation area analysis are also presented in this article. We present in here two instrument designs for thermal chemo-ablation and have completed the prototype design for the injection pump which has been tested and successfully applied in ex-vivo and vivo experiments.

  10. Exothermic relaxation and endothermic recrystallization of amorphous zirconium tungstate

    Science.gov (United States)

    Ramos, G. R.; Catafesta, J.; Zorzi, J. E.; da Jornada, J. A. H.; Perottoni, C. A.

    2011-09-01

    In a previous work, we have shown, by means of x-ray diffraction and differential thermal analysis measurements, that amorphous zirconium tungstate (a-ZrW2O8) undergoes endothermic recrystallization upon heating to above 900 K. Later on, the anomalous endothermic recrystallization did not become evident in results from drop calorimetry experiments conducted with zirconium tungstate. In this work, we provide evidences in support of the endothermic recrystallization of this compound and show that an exothermic structural relaxation prior to recrystallization may be the cause of the apparent controversy on the nature of the a-ZrW2O8 recrystallization. The net enthalpy of recrystallization was estimated as +1.8 kJ/mol. We also demonstrate, by means of in situ synchrotron x-ray diffraction measurements at high temperature, that a-ZrW2O8 recrystallizes into β-ZrW2O8 which, upon cooling, converts to α-ZrW2O8. The residual configurational entropy of (nonrelaxed) a-ZrW2O8 at 0 K was estimated as 8 Jgat-1K-1.

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

    DEFF Research Database (Denmark)

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

    2016-01-01

    A stepwise selection procedure is presented to quickly evaluate whether a given omega-transaminase reaction is suitable for a so-called "simple" scale-up for fast industrial implementation. Here "simple" is defined as a system without the need for extensive process development or specialized...

  12. Rapid and sensitive detection of Campylobacter spp. in chicken products by using the polymerase chain reaction

    NARCIS (Netherlands)

    Giesendorf, B A; Quint, W G; Henkens, M H; Stegeman, H; Huf, F A; Niesters, H G

    1992-01-01

    The polymerase chain reaction (PCR) after a short enrichment culture was used to detect Campylobacter spp. in chicken products. After the 16S rRNA gene sequence of Campylobacter jejuni was determined and compared with known sequences from other enterobacteria, a primer and probe combination was

  13. Rapid Heartbeat, But Dry Palms: Reactions of Heart Rate and Skin Conductance Levels to Social Rejection

    Directory of Open Access Journals (Sweden)

    Benjamin eIffland

    2014-08-01

    Full Text Available Background: Social rejection elicits negative mood, emotional distress and neural activity in networks that are associated with physical pain. However, studies assessing physiological reactions to social rejection are rare and results of these studies were found to be ambiguous. Therefore, the present study aimed to examine and specify physiological effects of social rejection.Methods: Participants (N = 50 were assigned to either a social exclusion or inclusion condition of a virtual ball-tossing game (Cyberball. Immediate and delayed physiological (skin conductance level and heart rate reactions were recorded. In addition, subjects reported levels of affect, emotional states and fundamental needs.Results: Subjects who were socially rejected showed increased heart rates. However, social rejection had no effect on subjects’ skin conductance levels. Both conditions showed heightened arousal on this measurement. Furthermore, psychological consequences of social rejection indicated the validity of the paradigm.Conclusions: Our results reveal that social rejection evokes an immediate physiological reaction. Accelerated heart rates indicate that behavior activation rather than inhibition is associated with socially threatening events. In addition, results revealed gender-specific response patterns suggesting that sample characteristics such as differences in gender may account for ambiguous findings of physiological reactions to social rejection.

  14. Rapid heartbeat, but dry palms: reactions of heart rate and skin conductance levels to social rejection.

    Science.gov (United States)

    Iffland, Benjamin; Sansen, Lisa M; Catani, Claudia; Neuner, Frank

    2014-01-01

    Social rejection elicits negative mood, emotional distress, and neural activity in networks that are associated with physical pain. However, studies assessing physiological reactions to social rejection are rare and results of these studies were found to be ambiguous. Therefore, the present study aimed to examine and specify physiological effects of social rejection. Participants (n = 50) were assigned to either a social exclusion or inclusion condition of a virtual ball-tossing game (Cyberball). Immediate and delayed physiological [skin conductance level (SCL) and heart rate] reactions were recorded. In addition, subjects reported levels of affect, emotional states, and fundamental needs. Subjects who were socially rejected showed increased heart rates. However, social rejection had no effect on subjects' SCLs. Both conditions showed heightened arousal on this measurement. Furthermore, psychological consequences of social rejection indicated the validity of the paradigm. Our results reveal that social rejection evokes an immediate physiological reaction. Accelerated heart rates indicate that behavior activation rather than inhibition is associated with socially threatening events. In addition, results revealed gender-specific response patterns suggesting that sample characteristics such as differences in gender may account for ambiguous findings of physiological reactions to social rejection.

  15. Rapid tomato volatile profiling by using proton-transfer reaction mass spectrometry (PTS-MS)

    NARCIS (Netherlands)

    Farneti, B.; Cristescu, S.M.; Costa, G.; Harren, F.J.M.; Woltering, E.J.

    2012-01-01

    The availability of rapid and accurate methods to assess fruit flavor is of utmost importance to support quality control especially in the breeding phase. Breeders need more information and analytical tools to facilitate selection for complex multigenic traits such as flavor quality. In this study,

  16. Thermochemistry and kinetics of graphite oxide exothermic decomposition for safety in large-scale storage and processing.

    Science.gov (United States)

    Qiu, Yang; Collin, Felten; Hurt, Robert H; Külaots, Indrek

    2016-01-01

    The success of graphene technologies will require the development of safe and cost-effective nano-manufacturing methods. Special safety issues arise for manufacturing routes based on graphite oxide (GO) as an intermediate due to its energetic behavior. This article presents a detailed thermochemical and kinetic study of GO exothermic decomposition designed to identify the conditions and material compositions that avoid explosive events during storage and processing at large scale. It is shown that GO becomes more reactive for thermal decomposition when it is pretreated with OH(-) in suspension and the effect is reversible by back-titration to low pH. This OH(-) effect can lower the decomposition reaction exotherm onset temperature by up to 50 degrees of Celsius, causing overlap with common drying operations (100-120°C) and possible self-heating and thermal runaway during processing. Spectroscopic and modeling evidence suggest epoxide groups are primarily responsible for the energetic behavior, and epoxy ring opening/closing reactions are offered as an explanation for the reversible effects of pH on decomposition kinetics and enthalpies. A quantitative kinetic model is developed for GO thermal decomposition and used in a series of case studies to predict the storage conditions under which spontaneous self-heating, thermal runaway, and explosions can be avoided.

  17. Rapid Heartbeat, But Dry Palms: Reactions of Heart Rate and Skin Conductance Levels to Social Rejection

    OpenAIRE

    Benjamin eIffland; Lisa Margareta Sansen; Claudia eCatani; Frank eNeuner

    2014-01-01

    Background: Social rejection elicits negative mood, emotional distress and neural activity in networks that are associated with physical pain. However, studies assessing physiological reactions to social rejection are rare and results of these studies were found to be ambiguous. Therefore, the present study aimed to examine and specify physiological effects of social rejection.Methods: Participants (N = 50) were assigned to either a social exclusion or inclusion condition of a virtual ball-to...

  18. Sinterable Ceramic Powders from Laser Heated Gas Phase Reactions and Rapidly Solidified Ceramic Materials.

    Science.gov (United States)

    1984-07-01

    Gattuso, T. R., Meunier, M., Adler, D., and Haggerty, J. S., "IR Laser- Induced Deposition of Silicon Thin Films ", to be published in the Proceedings of...and Thin Films by Laser Induced Gas Phase Reactions", presented at the Nineteenth University Conference on Ceramic Science, Emergent Process Methods... Silicon Carbonitrides from Monomeric Organosilicon Precursors". To be presented at the 1983 Annual Meeting of the American Ceramic Society, April 1983

  19. Rapid detection of respiratory syncytial virus in nasopharyngeal aspirates by reverse transcription and polymerase chain reaction amplification.

    Science.gov (United States)

    Paton, A W; Paton, J C; Lawrence, A J; Goldwater, P N; Harris, R J

    1992-01-01

    A rapid method for detection of respiratory syncytial virus (RSV) in nasopharyngeal aspirates, involving a combination of reverse transcription and polymerase chain reaction amplification (RT-PCR), has been developed. The RT-PCR assay employs oligonucleotide primers specific for the region of the RSV genome which encodes the F1 subunit of the fusion (F) glycoprotein. Other respiratory viruses do not give a positive reaction. The RT-PCR assay was tested on 202 nasopharyngeal aspirates collected from children with clinical signs of respiratory infection, and the results from RT-PCR were compared with those obtained from virus culture and direct detection by enzyme immunoassay (EIA). RT-PCR results were positive in 118 of 125 samples from which RSV was cultured, as well as in 4 of 7 samples which were culture negative but EIA positive. RT-PCR results were negative in 68 of 70 culture-negative, EIA-negative samples, which included 11 samples from which other respiratory viruses were isolated. The speed, sensitivity (94.6%), and specificity (greater than 97%) of the RT-PCR assay suggest that this technique could be useful for rapid detection of RSV in clinical samples. Images PMID:1374080

  20. Modeling of exothermic synthesis of composite with oxide inclusions

    Directory of Open Access Journals (Sweden)

    Knyazeva Anna

    2017-01-01

    Full Text Available The model is suggested for composite synthesis on the base of metallic matrix with inclusions of aluminum oxide at the conditions close to thermal explosion. Chemical reactions are described with the help of two summary stages. The melting, the dependence of reaction rates on pressure and reaction retardation by the product layer are taken into account. It was shown that during reactions proceeding in any regime the formation of final composition of the matrix does not occur. It agrees with known experimental data.

  1. Rapid and effective oxidative pretreatment of woody biomass at mild reaction conditions and low oxidant loadings.

    Science.gov (United States)

    Li, Zhenglun; Chen, Charles H; Hegg, Eric L; Hodge, David B

    2013-08-26

    One route for producing cellulosic biofuels is by the fermentation of lignocellulose-derived sugars generated from a pretreatment that can be effectively coupled with an enzymatic hydrolysis of the plant cell wall. While woody biomass exhibits a number of positive agronomic and logistical attributes, these feedstocks are significantly more recalcitrant to chemical pretreatments than herbaceous feedstocks, requiring higher chemical and energy inputs to achieve high sugar yields from enzymatic hydrolysis. We previously discovered that alkaline hydrogen peroxide (AHP) pretreatment catalyzed by copper(II) 2,2΄-bipyridine complexes significantly improves subsequent enzymatic glucose and xylose release from hybrid poplar heartwood and sapwood relative to uncatalyzed AHP pretreatment at modest reaction conditions (room temperature and atmospheric pressure). In the present work, the reaction conditions for this catalyzed AHP pretreatment were investigated in more detail with the aim of better characterizing the relationship between pretreatment conditions and subsequent enzymatic sugar release. We found that for a wide range of pretreatment conditions, the catalyzed pretreatment resulted in significantly higher glucose and xylose enzymatic hydrolysis yields (as high as 80% for both glucose and xylose) relative to uncatalyzed pretreatment (up to 40% for glucose and 50% for xylose). We identified that the extent of improvement in glucan and xylan yield using this catalyzed pretreatment approach was a function of pretreatment conditions that included H2O2 loading on biomass, catalyst concentration, solids concentration, and pretreatment duration. Based on these results, several important improvements in pretreatment and hydrolysis conditions were identified that may have a positive economic impact for a process employing a catalyzed oxidative pretreatment. These improvements include identifying that: (1) substantially lower H2O2 loadings can be used that may result in up to

  2. Economic analysis of rapid multiplex polymerase chain reaction testing for meningitis/encephalitis in pediatric patients.

    Science.gov (United States)

    Duff, Steve; Hasbun, Rodrigo; Ginocchio, Christine C; Balada-Llasat, Joan-Miquel; Zimmer, Louise; Bozzette, Samuel A

    2018-01-10

    We assessed the possible economic impact of a rapid test in pediatric patients with suspected community-acquired meningitis/encephalitis. Modeling simulated diagnosis, clinical decisions, resource use/costs of standard of care (SOC) and two cerebrospinal fluid testing strategies using FilmArray ® (FA), a US FDA-cleared system that provides results in approximately 1 h. Pathogens detected by FA caused approximately 75% of cases, 97% of which would be accurately diagnosed with FA.  Mean cost/case ranged from $17,599 to $22,025.  Syndromic testing is less expensive than SOC. Testing all suspected cases yielded greater savings ($3481/case) than testing only those with abnormal cerebrospinal fluid ($2157/case). Greater economic benefits are achievable with syndromic testing of all cases, rather than SOC or targeted syndromic testing.

  3. Nano-Phase Powder Based Exothermic Braze Repair Technology For RCC Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase II project will advance innovative, cost effective and reliable nano-phase exothermic RCC joining processes (ExoBrazeTM) in order to be able to reinforce...

  4. APPLICATION OF EXOTHERMIC PLUGS AT PRODUCTION OF STEEL CASTING IS THE WAY TO ECONOMY

    Directory of Open Access Journals (Sweden)

    V. M. Gatsuro

    2008-01-01

    Full Text Available It is shown that application of exothermic plugs allows to decrease steel intensity of casting mold, labor intensiveness for trim, expenses for melting of 1 ton of good casting, material expenses for burden materials.

  5. Numerical simulation of a plane turbulent mixing layer, with applications to isothermal, rapid reactions

    Science.gov (United States)

    Lin, P.; Pratt, D. T.

    1987-01-01

    A hybrid method has been developed for the numerical prediction of turbulent mixing in a spatially-developing, free shear layer. Most significantly, the computation incorporates the effects of large-scale structures, Schmidt number and Reynolds number on mixing, which have been overlooked in the past. In flow field prediction, large-eddy simulation was conducted by a modified 2-D vortex method with subgrid-scale modeling. The predicted mean velocities, shear layer growth rates, Reynolds stresses, and the RMS of longitudinal velocity fluctuations were found to be in good agreement with experiments, although the lateral velocity fluctuations were overpredicted. In scalar transport, the Monte Carlo method was extended to the simulation of the time-dependent pdf transport equation. For the first time, the mixing frequency in Curl's coalescence/dispersion model was estimated by using Broadwell and Breidenthal's theory of micromixing, which involves Schmidt number, Reynolds number and the local vorticity. Numerical tests were performed for a gaseous case and an aqueous case. Evidence that pure freestream fluids are entrained into the layer by large-scale motions was found in the predicted pdf. Mean concentration profiles were found to be insensitive to Schmidt number, while the unmixedness was higher for higher Schmidt number. Applications were made to mixing layers with isothermal, fast reactions. The predicted difference in product thickness of the two cases was in reasonable quantitative agreement with experimental measurements.

  6. Utility of a rapid immunochromatographic strip test in detecting canine parvovirus infection compared with polymerase chain reaction

    Directory of Open Access Journals (Sweden)

    Sundaran S. Tinky

    2015-04-01

    Full Text Available Aim: The present study was undertaken to detect the presence of canine parvovirus (CPV in fecal samples of diarrheic dogs by conventional polymerase chain reaction (PCR and immunochromatographic (IC strip test and to compare the diagnostic potential of these tests. Materials and Methods: A total of 50 fecal samples collected from diarrheic dogs suspected for CPV infection were subjected to PCR using CPV-555 primer amplifying the gene coding for the VP1 protein. These samples were also tested by IC strip test using a commercial rapid Ag test kit. The results were statistically analyzed using McNemar test. Results: A total of 22 samples (44% were detected as positive by PCR, which yielded a specific amplicon of 583 bp. In IC strip test, 18 (36% samples were found to be positive. The sensitivity of the test as compared to PCR was found to be 72.22% and specificity was 92.86%. Positive predictive value and negative predictive value of IC strip test was found to be 88.89% and 81.25%, respectively. Statistical analysis of the results of PCR and IC assay using McNemar test revealed no significant difference (p>0.05. Conclusion: The IC strip test could be employed as a rapid field level diagnostic tool for the diagnosis of canine parvoviral diarrhea.

  7. Rapid genetically modified organism (GMO screening of various food products and animal feeds using multiplex polymerase chain reaction (PCR

    Directory of Open Access Journals (Sweden)

    Lisha, V.

    2017-01-01

    Full Text Available modified crops which brought up a controversy on the safety usage of genetically modified organisms (GMOs. It has been implemented globally that all GMO products and its derived ingredients should have regulations on the usage and labelling. Thus, it is necessary to develop methods that allow rapid screening of GMO products to comply with the regulations. This study employed a reliable and flexible multiplex polymerase chain reaction (PCR method for the rapid detection of transgenic elements in genetically modified soy and maize along with the soybean LECTIN gene and maize ZEIN gene respectively. The selected four common transgenic elements were 35S promoter (35S; Agrobacterium tumefaciens nopaline synthase terminator (NOS; 5-enolypyruvylshikimate-3-phosphate synthase (epsps gene; and Cry1Ab delta-endotoxin (cry1Ab gene. Optimization of the multiplex PCR methods were carried out by using 1% Roundup ReadyTM Soybean (RRS as the certified reference material for soybean that produced fourplex PCR method detecting 35S promoter, NOS terminator, epsps gene and soybean LECTIN gene and by using 1% MON810 as the certified reference material for maize that produced triplex PCR method detecting 35S promoter, cry1Ab gene and maize ZEIN gene prior to screening of the GMO traits in various food products and animal feeds. 1/9 (11.1% of the animal feed contained maize and 1/15 (6.7% of the soybean food products showed positive results for the detection of GMO transgenic gene. None of the maize food products showed positive results for GMO transgenic gene. In total, approximately 4% of the food products and animal feed were positive as GMO. This indicated GMOs have not widely entered the food chain. However, it is necessary to have an appropriate screening method due to GMOs’ unknown potential risk to humans and to animals. This rapid screening method will provide leverage in terms of being economically wise, time saving and reliable.

  8. A catalytically membrane reactor for fast, highly exothermic, heterogeneous gas reactions : a pilot plant study

    NARCIS (Netherlands)

    Veldsink, J.W.; Veldsink, J.W.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1995-01-01

    Membrane reactors have been frequently studied because of their ability to combine chemical activity and separation properties into one device. Due to their thermal stability and mechanical strength, ceramic membranes are preferred over polymeric ones, but small transmembrane fluxes obstruct a

  9. A Catalytically Active Membrane Reactor for Fast, Highly Exothermic, Heterogeneous Gas Reactions. A Pilot Plant Study

    NARCIS (Netherlands)

    Veldsink, Jan W.; Versteeg, Geert F.; Swaaij, Wim P.M. van

    1995-01-01

    Membrane reactors have been frequently studied because of their ability to combine chemical activity and separation properties into one device. Due to their thermal stability and mechanical strength, ceramic membranes are preferred over polymeric ones, but small transmembrane fluxes obstruct a

  10. Synthesis of High-Purity SnO2 Nanobelts by Using Exothermic Reaction

    Directory of Open Access Journals (Sweden)

    Guodong Zhang

    2011-01-01

    Full Text Available This paper presents a new method to synthesize high-purity single-crystalline SnO2 nanobelts with rutile structure. The purity, morphology, crystal structure, and sizes of the as-grown SnO2 nanobelts are characterized by X-ray diffraction, energy-dispersive X-ray analysis, scanning electron microscopy, transmission electron microscopy, and Raman-scattering spectroscopy. The scanning electron microscopy and transmission electron microscopy reveal tetragonal SnO2 nanobelts of 50–120 nm in width, 20–50 nm in thickness, and 2–10 μm in length. The three observed Raman peaks at 475, 633, and 774 cm−1 indicate the typical rutile structure of the SnO2, which is in agreement with the X-ray diffraction results, and other peaks of impurity are not found. High-resolution transmission electron microscopy demonstrates that the nanobelts have a high degree of crystallinity, without typical imperfects in it. And the growth mechanism of the SnO2 nanobelts is discussed.

  11. Exothermic Surface Reactions in Alumina-Aluminum Shell-Core Nanoparticles with Iodine Oxide Decomposition Fragments

    Science.gov (United States)

    2014-02-22

    aluminum and iodine pentoxide (I2O5) powder mixtures. Various equivalence ratios were examined and found to affect the PIR onset temperature. Prior to this...alumina– alumin Approved for public release; distribution is unlimited. 58857.45-EG REPORT DOCUMENTATION PAGE (SF298) (Continuation Sheet...and iodine pentoxide (I2O5) powder mixtures. Various equivalence ratios were examined and found to affect the PIR onset temper- ature. Prior to this

  12. Comment on "Enhanced Diffusion of Enzymes that Catalyze Exothermic Reactions" by R.Golestanian

    CERN Document Server

    Tsekouras, K; Gabizon, R; Marqusee, S; Pressé, S; Bustamante, C

    2016-01-01

    We (Riedel et al. Nature 2015), as well as others, have showed that some enzymes exhibit enhanced diffusion when active. In a recent PRL, (Golestanian, PRL 2015, arXiv:1508.03219) R.Golestanian theoretically examines a number of possible explanations for this phenomenon and concludes that "collective heating" is the best candidate to account for the observed diffusion coefficient increase. Here we present evidence showing that collective heating cannot possibly apply to our experiments.

  13. Rapid and Sensitive Detection of Phytophthora sojae in Soil and Infected Soybeans by Species-Specific Polymerase Chain Reaction Assays.

    Science.gov (United States)

    Wang, Yuanchao; Zhang, Wenli; Wang, Ying; Zheng, Xiaobo

    2006-12-01

    ABSTRACT Root and stem rot caused by Phytophthora sojae is one of the most destructive diseases of soybean (Glycine max) worldwide. P. sojae can survive as oospores in soil for many years. In order to develop a rapid and accurate method for the specific detection of P. sojae in soil, the internal transcribed spacer (ITS) regions of eight P. sojae isolates were amplified using polymerase chain reaction (PCR) with the universal primers DC6 and ITS4. The sequences of PCR products were aligned with published sequences of 50 other Phytophthora species, and a region specific to P. sojae was used to design the specific PCR primers, PS1 and PS2. More than 245 isolates representing 25 species of Phytophthora and at least 35 other species of pathogens were used to test the specificity of the primers. PCR amplification with PS primers resulted in the amplification of a product of approximately 330 bp, exclusively from isolates of P. sojae. Tests with P. sojae genomic DNA determined that the sensitivity of the PS primer set is approximately 1 fg. This PCR assay, combined with a simple soil screening method developed in this work, allowed the detection of P. sojae from soil within 6 h, with a detection sensitivity of two oospores in 20 g of soil. PCR with the PS primers could also be used to detect P. sojae from diseased soybean tissue and residues. Real-time fluorescent quantitative PCR assays were also developed to detect the pathogen directly in soil samples. The PS primer-based PCR assay provides a rapid and sensitive tool for the detection of P. sojae in soil and infected soybean tissue.

  14. Prediction and Prevention of Chemical Reaction Hazards: Learning by Simulation.

    Science.gov (United States)

    Shacham, Mordechai; Brauner, Neima; Cutlip, Michael B.

    2001-01-01

    Points out that chemical hazards are the major cause of accidents in chemical industry and describes a safety teaching approach using a simulation. Explains a problem statement on exothermic liquid-phase reactions. (YDS)

  15. Rapid determination of parabens in personal care products by stable isotope GC-MS/MS with dynamic selected reaction monitoring.

    Science.gov (United States)

    Wang, Perry G; Zhou, Wanlong

    2013-06-01

    In this study, a rapid and sensitive analytical method for the determination of methyl-, ethyl-, propyl-, and butyl esters of para-hydroxy benzoic acid (parabens) in personal care products was developed and fully validated. Test portions were extracted with methanol followed by vortexing, sonication, centrifugation, and filtration without derivatization. The four parabens were quantified by GC-MS/MS in the electron ionization mode. Four corresponding isotopically labeled parabens were selected as internal standards, which were added at the beginning of the sample preparation and used to correct for recovery and matrix effects. Sensitivity, extraction efficiency, and recovery of the respective analytes were evaluated. The coefficients of determination (r(2)) were all greater than 0.995 for the four parabens investigated. The recoveries ranged from 97 to 107% at three spiked levels and a one-time (single) extraction efficiency greater than 97% was obtained. This method has been applied to screen 26 personal care products. This is the first time that a unique GC-MS/MS method with dynamic selected reaction monitoring and confirmation of analytes has been used to determine these parabens in cosmetic personal care products. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Detection of clarithromycin-resistant Helicobacter pylori by polymerase chain reaction using residual samples from rapid urease test

    Directory of Open Access Journals (Sweden)

    Jae-Sik Jeon

    2017-01-01

    Full Text Available Background: Approximately 50% of the world population is infected with Helicobacter pylori, which corresponds to a high infection rate. Furthermore, the incidence of antibiotic-resistant H. pylori has increased with the recent rise in use of antibiotics for H. pylori elimination, suggesting growing treatment failures. Aim: The study was aimed to assess the use of residual samples from rapid urease test (RUT for biomolecular testing as an effective and accurate method to detect antibiotic-resistant H. pylori. Settings and Design: This study was a retrospective study performed using data obtained from medical records of previously isolated H. pylori strains. Materials and Methods: RUT was conducted for 5440 biopsy samples from individuals who underwent health examination in South Korea. Subsequently, 469 RUT residual samples were randomly selected and subjected to polymerase chain reaction (PCR to detect antibiotic-resistant H. pylori. Statistical Analysis Used: The Chi-square test was used to analyse categorical data. P < 0.05 was considered statistically significant. Results: The results showed a concordance between the results of PCR and conventional RUT in 450 of 469 samples, suggesting that the H. pylori PCR test is a time- and cost-effective detection method. Conclusions: This study demonstrated that PCR test can aid physicians to prescribe the appropriate antibiotics at the time of diagnosis, thus preventing the reduction in H. pylori eradication due to antibiotic resistance, averting progression to serious diseases and increasing the treatment success rate.

  17. Direct polymerase chain reaction from blood and tissue samples for rapid diagnosis of bovine leukemia virus infection.

    Science.gov (United States)

    Nishimori, Asami; Konnai, Satoru; Ikebuchi, Ryoyo; Okagawa, Tomohiro; Nakahara, Ayako; Murata, Shiro; Ohashi, Kazuhiko

    2016-06-01

    Bovine leukemia virus (BLV) infection induces bovine leukemia in cattle and causes significant financial harm to farmers and farm management. There is no effective therapy or vaccine; thus, the diagnosis and elimination of BLV-infected cattle are the most effective method to eradicate the infection. Clinical veterinarians need a simpler and more rapid method of diagnosing infection, because both nested polymerase chain reaction (PCR) and real-time PCR are labor intensive, time-consuming, and require specialized molecular biology techniques and expensive equipment. In this study, we describe a novel PCR method for amplifying the BLV provirus from whole blood, thus eliminating the need for DNA extraction. Although the sensitivity of PCR directly from whole blood (PCR-DB) samples as measured in bovine blood containing BLV-infected cell lines was lower than that of nested PCR, the PCR-DB technique showed high specificity and reproducibility. Among 225 clinical samples, 49 samples were positive by nested PCR, and 37 samples were positive by PCR-DB. There were no false positive samples; thus, PCR-DB sensitivity and specificity were 75.51% and 100%, respectively. However, the provirus loads of the samples detected by nested PCR and not PCR-DB were quite low. Moreover, PCR-DB also stably amplified the BLV provirus from tumor tissue samples. PCR-DB method exhibited good reproducibility and excellent specificity and is suitable for screening of thousands of cattle, thus serving as a viable alternative to nested PCR and real-time PCR.

  18. Rapid and sensitive method for the detection of Aeromonas caviae and Aeromonas trota by polymerase chain reaction.

    Science.gov (United States)

    Khan, A A; Cerniglia, C E

    1997-04-01

    A 16S rDNA-based polymerase chain reaction (PCR) method was developed for the detection of Aeromonas caviae and Aeromonas trota. These two species were identified from other Aeromonas spp. and closely related species by primers set (AER1 and AER2). The amplified product was 316 bp. The identity of the amplified product was confirmed by DNA-DNA hybridization. Two sets of primers (AER8 and AER9) were used for specific identification of Aer. caviae. Amplifying the 260 bp fragment of 16S rRNA gene region and digesting it with AluI restriction enzyme, yielded 180- and 80-bp fragments. For PCR assay, template DNA was released by mixing equal volumes of homogenized seeded crab meat with Aer. caviae and Chelex 100 (6%) incubated for 10 min at 56 degrees C followed by addition of an equal volume of 0.1% Triton-X-100 and boiled for 10 min. The detection limit was between 50 and 100 cells g-1 of crab meat. This method is very rapid and obviates the need for DNA isolation from complex food matrices and is specific for detecting two Aeromonas species.

  19. Proton Transfer Reaction Mass Spectrometry detects rapid changes in volatile metabolite emission by Mycobacterium smegmatis after the addition of specific antimicrobial agents

    NARCIS (Netherlands)

    Crespo, E.; Cristescu, S. M.; de Ronde, H.; Kuijper, S.; Kolk, A.H.J.; Anthony, R.M.; Harren, F. J. M.

    2011-01-01

    The metabolic activity of plants, animals or microbes can be monitored by gas headspace analysis. This can be achieved using Proton Transfer Reaction Mass Spectrometry (PTR-MS), a highly sensitive detection method for trace gas analysis. PTR-MS is rapid and can detect metabolic responses on-line as

  20. Preparation of a Rapidly Forming Poly(ferrocenylsilane)-Poly(ethylene glycol)-based Hydrogel by a Thiol–Michael Addition Click Reaction

    NARCIS (Netherlands)

    Sui, Xiaofeng; van Ingen, Lennard; Hempenius, Mark A.; Vancso, Gyula J.

    2010-01-01

    The synthesis of a rapidly forming redox responsive poly(ferrocenylsilane)-poly(ethylene glycol) (PFS-PEG)-based hydrogel is described, achieved by a thiol-Michael addition click reaction. PFS bearing acrylate side groups (PFS-acryl) was synthesized by side group modification of

  1. Production of H2 from combined endothermic and exothermic hydrogen carriers.

    Science.gov (United States)

    Wechsler, Dominik; Cui, Yi; Dean, Darrell; Davis, Boyd; Jessop, Philip G

    2008-12-17

    One of the major limitations to the use of fuel cell systems in vehicular transportation is the lack of hydrogen storage systems that have the required hydrogen storage density and moderate enthalpy of dehydrogenation. Organic liquid H(2) carriers that release H(2) endothermically are easier to handle with existing infrastructure because they are liquids, but they have low storage densities and their endothermicity consumes energy in the vehicle. On the other hand, inorganic solid H(2) carriers that release H(2) exothermically have greater storage densities but are unpumpable solids. This paper explores combinations of an endothermic carrier and an exothermic carrier, where the exothermic carrier provides some or all of the necessary heat required for dehydrogenation to the endothermic system, and the endothermic carrier serves as a solvent for the exothermic carrier. The two carriers can be either physically mixed or actually bonded to each other. To test the latter strategy, a number of chemically bound N-heterocycle:BH(3) adducts were synthesized and in turn tested for their ability to release H(2) by tandem hydrolysis of the BH(3) moiety and dehydrogenation of the heterocycle. To test the strategy of physically mixing two carriers, the hydrolysis of a variety of amine-boranes (H(3)N:BH(3), Me(2)HN:BH(3), Et(3)N:BH(3)) and the catalytic dehydrogenation of indoline were carried out together.

  2. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP for rapid diagnosis of neonatal sepsis

    Directory of Open Access Journals (Sweden)

    Anusha Rohit

    2016-01-01

    Full Text Available Background & objectives: The difficulties in diagnosis of neonatal sepsis are due to varied clinical presentation, low sensitivity of blood culture which is considered the gold standard and empirical antibiotic usage affecting the outcome of results. Though polymerase chain reaction (PCR based detection of bacterial 16S rRNA gene has been reported earlier, this does not provide identification of the causative agent. In this study, we used restriction fragment length polymorphism (RFLP of amplified 16S rRNA gene to identify the organisms involved in neonatal sepsis and compared the findings with blood culture. Methods: Blood samples from 97 neonates were evaluated for diagnosis of neonatal sepsis using BacT/Alert (automated blood culture and PCR-RFLP. Results: Bacterial DNA was detected by 16S rRNA gene PCR in 55 cases, while BacT/Alert culture was positive in 34 cases. Staphylococcus aureus was the most common organism detected with both methods. Klebsiella spp. was isolated from four samples by culture but was detected by PCR-RFLP in five cases while Acinetobacter spp. was isolated from one case but detected in eight cases by PCR-RFLP. The sensitivity of PCR was found to be 82.3 per cent with a negative predictive value of 85.7 per cent. Eighty of the 97 neonates had prior exposure to antibiotics. Interpretation & conclusions:The results of our study demonstrate that PCR-RFLP having a rapid turnaround time may be useful for the early diagnosis of culture negative neonatal sepsis.

  3. Characterizing the Performance of a Proton-Transfer-Reaction Mass Spectrometer with a Rapid Cycling Tenax Preconcentrator

    Energy Technology Data Exchange (ETDEWEB)

    Garland, S.P.; Alexander, M.L.

    2006-01-01

    Volatile organic compounds (VOCs) are species of interest for atmospheric modeling, worker chemical exposure and medical studies. Sometimes the required detection limits for these compounds is below the capability of existing real-time instrumentation. Preconcentrators have been implemented as an inexpensive way to amplify chemical signals and improve detection limits. Proton-transfer-reaction mass spectrometry (PTR-MS) has been used as a tool for studying low concentrations of VOCs, but it lacks the capability to differentiate chemical signal contributions from isobaric compounds. In this work, behavior of a newly designed Tenax TA preconcentrator when coupled with a PTRMS is characterized. This novel preconcentrator design allows rapid temperature cycling, maintaining near real-time response. The preconcentrator was exposed to a sample gas of toluene in varying concentrations and loading times between and then thermally desorbed for analysis by PTR-MS. The effects of preconcentrating multiple analytes simultaneously were also investigated as well as the chromatographic effects of the preconcentrator. A linear behavior was observed when the integrated ion count rates (ICPS) from thermal desorption peaks were regressed against both varying loading times at a constant toluene concentration and varying concentrations with constant loading times. From these trends, it is possible to determine the concentration of a VOC by knowing its ICPS from thermal desorption peaks from a known preconcentration time. Peak height ion count rates representing ultimate detectability were amplified by factors up to 257 times the original signal, extending the range of the PTR-MS from 50pptv to nearly 250 parts per quadrillion. This corresponds to an ultimate sensitivity of 200 parts per quadrillion with 20 minute time resolution. Quantitative preconcentrator behavior was demonstrated using ICPS from these ion peaks and were amplified as much as 148 times their original signal. Results

  4. A temperature control method for shortening thermal cycling time to achieve rapid polymerase chain reaction (PCR) in a disposable polymer microfluidic device

    DEFF Research Database (Denmark)

    Bu, Minqiang; Perch-Nielsen, Ivan R.; Sørensen, Karen Skotte

    2013-01-01

    We present a temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with an external heater and a temperature sensor. The method employs optimized temperature overshooting and undershooting...... steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature-dependent fluorescence...

  5. A novel temperature control method for shortening thermal cycling time to achieve rapid polymerase chain reaction (PCR) in a disposable polymer microfluidic device

    DEFF Research Database (Denmark)

    Bu, Minqiang; R. Perch-Nielsen, Ivan; Sørensen, Karen Skotte

    We present a new temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with external heater and temperature sensor. The method employs optimized temperature overshooting and undershooting...... steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature dependent fluorescence...

  6. A randomized trial of exothermic mattresses for preterm newborns in polyethylene bags.

    LENUS (Irish Health Repository)

    McCarthy, Lisa K

    2013-07-01

    Hypothermia on admission to the NICU is associated with increased mortality in preterm infants. Many newborns are hypothermic on admission despite using polyethylene bags (PBs). Using exothermic mattresses (EMs) in addition to PBs may reduce hypothermia but increase hyperthermia. We wished to determine whether placing preterm newborns in PBs on EMs in the DR results in more infants with rectal temperature outside the range 36.5 to 37.5°C on NICU admission.

  7. Calculation of reaction energies and adiabatic temperatures for waste tank reactions

    Energy Technology Data Exchange (ETDEWEB)

    Burger, L.L.

    1993-03-01

    Continual concern has been expressed over potentially hazardous exothermic reactions that might occur in underground Hanford waste tanks. These tanks contain many different oxidizable compounds covering a wide range of concentrations. Several may be in concentrations and quantities great enough to be considered a hazard in that they could undergo rapid and energetic chemical reactions with nitrate and nitrite salts that are present. The tanks also contain many inorganic compounds inert to oxidation. In this report the computed energy that may be released when various organic and inorganic compounds react is computed as a function of the reaction mix composition and the temperature. The enthalpy, or integrated heat capacity, of these compounds and various reaction products is presented as a function of temperature, and the enthalpy of a given mixture can then be equated to the energy release from various reactions to predict the maximum temperature that may be reached. This is estimated for several different compositions. Alternatively, the amounts of various diluents required to prevent the temperature from reaching a critical value can be estimated.

  8. In situ generation of steam and alkaline surfactant for enhanced oil recovery using an exothermic water reactant (EWR)

    Science.gov (United States)

    Robertson, Eric P

    2011-05-24

    A method for oil recovery whereby an exothermic water reactant (EWR) encapsulated in a water soluble coating is placed in water and pumped into one or more oil wells in contact with an oil bearing formation. After the water carries the EWR to the bottom of the injection well, the water soluble coating dissolves and the EWR reacts with the water to produce heat, an alkali solution, and hydrogen. The heat from the EWR reaction generates steam, which is forced into the oil bearing formation where it condenses and transfers heat to the oil, elevating its temperature and decreasing the viscosity of the oil. The aqueous alkali solution mixes with the oil in the oil bearing formation and forms a surfactant that reduces the interfacial tension between the oil and water. The hydrogen may be used to react with the oil at these elevated temperatures to form lighter molecules, thus upgrading to a certain extent the oil in situ. As a result, the oil can flow more efficiently and easily through the oil bearing formation towards and into one or more production wells.

  9. Gender Differences among Sagittal Plane Knee Kinematic and Ground Reaction Force Characteristics during a Rapid Sprint and Cut Maneuver

    Science.gov (United States)

    James, C. Roger; Sizer, Phillip S.; Starch, David W.; Lockhart, Thurmon E.; Slauterbeck, James

    2004-01-01

    Women are more prone to anterior cruciate ligament (ACL) injury during cutting sports than men. The purpose of this study was to examine knee kinematic and ground reaction forces (GRF) differences between genders during cutting. Male and female athletes performed cutting trials while force platform and video data were recorded (180 Hz).…

  10. Quantum-State Controlled Chemical Reactions of Ultracold Potassium-Rubidium Molecules

    National Research Council Canada - National Science Library

    S. Ospelkaus; K.-K. Ni; D. Wang; M. H. G. de Miranda; B. Neyenhuis; G. Queméméner; P. S. Julienne; J. L. Bohn; D. S. Jin; J. Ye

    2010-01-01

    ...? Starting with an optically trapped near-quantum-degenerate gas of polar 40 K 87 Rb molecules prepared in their absolute ground state, we report experimental evidence for exothermic atom-exchange chemical reactions...

  11. Rapid decolorization of dye Orange G by microwave enhanced Fenton-like reaction with delafossite-type CuFeO2.

    Science.gov (United States)

    Cai, Mei-Qiang; Zhu, Yi-Zu; Wei, Zong-Su; Hu, Jian-Qiang; Pan, Sheng-Dong; Xiao, Rui-Yang; Dong, Chun-Ying; Jin, Mi-Cong

    2017-02-15

    Bimetallic oxide CuFeO2 as a new heterogeneous catalyst has shown much higher catalytic ability for activating peroxide than single-metal oxides. The present work demonstrated a synergistic microwave (MW) enhanced Fenton-like process with CuFeO2 for rapid decolorization of azo dye Orange G (OG). The MW irradiation dramatically enhanced the OG degradation efficiency, achieving 99.9% decolorization within 15min at pH5. The XRD analysis of reused CuFeO2, together with metal leaching tests, indicated merits of recycling for CuFeO2. The subsequent surface element analysis by XPS for fresh and used CuFeO2 showed a complex network for reactions between copper-iron redox pairs and surface hydroxyl groups, leading to a synergistic Fenton-like system accelerated by MW irradiation. In the CuFeO2 initiated Fenton-like reactions, several oxidant species (i.e., OH, O2-, electron hole, and FeIVO) responsible to the OG oxidation were identified by quenching experiments, showing the MW generated high temperature and "hot spots" enhanced the yield of OH by generation of electron-hole pairs. Further, the 26 detected degradation products confirmed the OH dominant oxidation of OG. This study shows that the MW-enhanced Fenton-like reaction using CuFeO2 has potential applications for rapid decolorization of dye effluent. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Mechanical Reaction of Facial Skeleton to Rapid Palatal Expansion Devices using Laser Holography: An in vitro Study

    Directory of Open Access Journals (Sweden)

    Revathi Peddu

    2013-01-01

    Conclusion: Hyrax appliance activation produced mechanical reactions on the teeth, alveolar bone, maxilla and the circum-maxillary bones and sutures. The displacement and fringes increased progressively with two, four and eight turns activation of hyrax. The pattern of the fringes was more circular around the nasomaxillary complex and zygomaticomaxillary sutures, suggesting rotational displacement of the maxilla. The number and pattern of fringes produced by the Spring jet appliances suggest that it produces only dentoalveolar changes and minimal orthopedic affects.

  13. Microwave-assisted multicomponent reactions for rapid synthesis of AIE-active fluorescent polymeric nanoparticles by post-polymerization method.

    Science.gov (United States)

    Cao, Qian-Yong; Jiang, Ruming; Liu, Meiying; Wan, Qing; Xu, Dazhuang; Tian, Jianwen; Huang, Hongye; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2017-11-01

    The development of simple and effective methods for synthesis of fluorescent polymeric nanoparticles (FPNs) with aggregation-induced emission (AIE) plays an important role for the biomedical applications of AIE-active FPNs. In present work, we developed a facile strategy for the fabrication of AIE-active FPNs by a post-polymerization method based on the microwave-assisted Kabachnik-Fields (KF) reaction, which can conjugate with poly(PEGMA-NH2), AIE-active dye (TPE-CHO) and diethyl phosphate (DP) under microwave irradiation within 5min. The characterization results confirm that PEGMA-TPE FPNs are successfully prepared through the microwave-assisted KF reaction. The resultant AIE-active FPNs show high water dispersity, intensive fluorescence and low cytotoxicity. These features make these AIE-active FPNs great potential for biomedical applications. Moreover, the microwave-assisted KF reaction is simple, fast, atom economy that should be a general strategy for the fabrication of various multifunctional AIE-active FPNs. We believe this work will open up a new avenue for the preparation of AIE-active functional materials with great potential for different applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Rapid optimization of the post-column fluorogenic ninhydrin reaction for the HPLC-based determination of bradykinin and related fragments.

    Science.gov (United States)

    Wimalasena, R; Audus, K L; Stobaugh, J F

    2003-01-01

    A flow injection analysis scheme is demonstrated for the rapid optimization of reagent concentrations, flow rates, delay time and temperature using the guanidino moiety specific fluorogenic ninhydrin reaction. Using the amino acid arginine, non-arginine containing peptides, and the arginine-containing peptides, bradykinin and related fragments, specificity is demonstrated. These results serve to extend previous descriptions of the post-column reaction by offering a time efficient approach for the optimization of newly assembled post-column reactors using this chemistry. The reactor is subsequently added to a gradient elution HPLC system with the separation of bradykinin and bradykinin fragments demonstrated. Detection sensitivity in the high femtomole-low picomole mass range was achieved for these substances. Copyright 2003 John Wiley & Sons, Ltd.

  15. Multiplex reverse transcription-polymerase chain reaction combined with on-chip electrophoresis as a rapid screening tool for candidate gene sets

    DEFF Research Database (Denmark)

    Wittig, Rainer; Salowsky, Rüdiger; Blaich, Stephanie

    2005-01-01

    Combining multiplex reverse transcription-polymerase chain reaction (mRT-PCR) with microfluidic amplicon analysis, we developed an assay for the rapid and reliable semiquantitative expression screening of 11 candidate genes for drug resistance in human malignant melanoma. The functionality...... of this approach was demonstrated by low interexperimental variations of amplicon quantities after endpoint analysis. When applied to RNA samples derived from drug-sensitive and -resistant melanoma cell lines, mRT-PCR delivered results qualitatively concordant with data obtained from Northern blot and array...... analyses. The screening of additional melanoma cell lines resulted in distinct expression patterns for ten candidate genes. Our approach reveals a rapid and easy-to-handle alternative for candidate gene set evaluation from limited amounts of RNA....

  16. A colorimetric assay of 1-aminocyclopropane-1-carboxylate (ACC) based on ninhydrin reaction for rapid screening of bacteria containing ACC deaminase.

    Science.gov (United States)

    Li, Z; Chang, S; Lin, L; Li, Y; An, Q

    2011-08-01

    1-Aminocyclopropane-1-carboxylate (ACC) deaminase activity is an efficient marker for bacteria to promote plant growth by lowering ethylene levels in plants. We aim to develop a method for rapidly screening bacteria containing ACC deaminase, based on a colorimetric ninhydrin assay of ACC. A reliable colorimetric ninhydrin assay was developed to quantify ACC using heat-resistant polypropylene chimney-top 96-well PCR plates, having the wells evenly heated in boiling water, preventing accidental contamination from boiling water and limiting evaporation. With this method to measure bacterial consumption of ACC, 44 ACC-utilizing bacterial isolates were rapidly screened out from 311 bacterial isolates that were able to grow on minimal media containing ACC as the sole nitrogen source. The 44 ACC-utilizing bacterial isolates showed ACC deaminase activities and belonged to the genus Burkholderia, Pseudomonas or Herbaspirillum. Determination of bacterial ACC consumption by the PCR-plate ninhydrin-ACC assay is a rapid and efficient method for screening bacteria containing ACC deaminase from a large number of bacterial isolates. The PCR-plate ninhydrin-ACC assay extends the utility of the ninhydrin reaction and enables a rapid screening of bacteria containing ACC deaminase from large numbers of bacterial isolates. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

  17. Rapid detection of active cytomegalovirus infection by in situ polymerase chain reaction on MRC5 cells inoculated with blood specimens.

    Science.gov (United States)

    Bettinger, D; Mougin, C; Lab, M

    1994-08-01

    An in situ polymerase chain reaction was developed to amplify immediate early genes of human cytomegalovirus in cells cultured in a 96 well plate and infected with leukocytes. The technical parameters enabling optimal detection of the DNA sequences were defined. The key to this method is the fixation of cells, which facilitates the access of the PCR mixture into the cell nuclei and preserves cell morphology. Such a technique could have wide application for the detection and identification of other infectious viruses in cultured cells very early after inoculation of clinical samples.

  18. Rapid identification of pathogens from positive blood cultures by multiplex polymerase chain reaction using the FilmArray system.

    Science.gov (United States)

    Blaschke, Anne J; Heyrend, Caroline; Byington, Carrie L; Fisher, Mark A; Barker, Elizabeth; Garrone, Nicholas F; Thatcher, Stephanie A; Pavia, Andrew T; Barney, Trenda; Alger, Garrison D; Daly, Judy A; Ririe, Kirk M; Ota, Irene; Poritz, Mark A

    2012-12-01

    Sepsis is a leading cause of death. Rapid and accurate identification of pathogens and antimicrobial resistance directly from blood culture could improve patient outcomes. The FilmArray® (FA; Idaho Technology, Salt Lake City, UT, USA) Blood Culture (BC) panel can identify >25 pathogens and 4 antibiotic resistance genes from positive blood cultures in 1 h. We compared a development version of the panel to conventional culture and susceptibility testing on 102 archived blood cultures from adults and children with bacteremia. Of 109 pathogens identified by culture, 95% were identified by FA. Among 111 prospectively collected blood cultures, the FA identified 84 (91%) of 92 pathogens covered by the panel. Among 25 Staphylococcus aureus and 21 Enterococcus species detected, FA identified all culture-proven methicillin-resistant S. aureus and vancomycin-resistant enterococci. The FA BC panel is an accurate method for the rapid identification of pathogens and resistance genes from blood culture. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. The catalase reaction of Shigella species and its use in rapid screening for epidemic Shigella dysenteriae type 1.

    Science.gov (United States)

    Karas, J A; Pillay, D G; Sturm, A W

    2007-01-01

    As epidemic dysentery caused by Shigella dysenteriae type 1 is associated with high mortality, early identification of outbreaks is important. Since S. dysenteriae type 1 differs from most of the Enterobacteriaceae in that it does not produce catalase, a test for catalase may provide a useful screening method. The ability of a catalase test to provide rapid identification of S. dysenteriae type 1 has now been assessed, using isolates of this pathogen from five continents, Shigella of other species, and entero-invasive (EIEC) and Shiga-toxin-producing Escherichia coli (STEC). All of the isolates of S. dysenteriae type 1, as well as S. dysenteriae of types 3, 4, 6, 9, 11 and 12 and S. boydii of type 12, were found catalase-negative. All the other bacteria tested were positive for catalase. In an epidemic setting in South Africa, 406 xylose-negative and lysine-decarboxylase-negative isolates, collected from xylose-lysine-deoxycholate (XLD) agar, were tested for catalase. All 356 of the catalase-negative isolates were confirmed to be of S. dysenteriae type 1. None of the catalase-positive isolates were of S. dysenteriae type 1. The catalase test is useful in the rapid, presumptive identification of S. dysenteriae type 1, from appropriate culture media, because of its high predictive value, simplicity and speed. It would be particularly useful during dysentery outbreaks, when other Shigella would be uncommon. There was no association between the absence of catalase activity and the production of Shiga toxin.

  20. Rapid determination of trace copper in animal feed based on micro-plate colorimetric reaction and statistical partitioning correction.

    Science.gov (United States)

    Niu, Yiming; Wang, Jiayi; Zhang, Chi; Chen, Yiqiang

    2017-04-15

    The objective of this study was to develop a micro-plate based colorimetric assay for rapid and high-throughput detection of copper in animal feed. Copper ion in animal feed was extracted by trichloroacetic acid solution and reduced to cuprous ion by hydroxylamine. The cuprous ion can chelate with 2,2'-bicinchoninic acid to form a Cu-BCA complex which was detected with high sensitivity by micro-plate reader at 354nm. The whole assay procedure can be completed within 20min. To eliminate matrix interference, a statistical partitioning correction approach was proposed, which makes the detection of copper in complex samples possible. The limit of detection was 0.035μg/mL and the detection range was 0.1-10μg/mL of copper in buffer solution. Actual sample analysis indicated that this colorimetric assay produced results consistent with atomic absorption spectrometry analysis. These results demonstrated that the developed assay can be used for rapid determination of copper in animal feed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. In vitro pulp chamber temperature rise from irradiation and exotherm of flowable composites.

    Science.gov (United States)

    Baroudi, Kusai; Silikas, Nick; Watts, David C

    2009-01-01

    The aim of this study was to investigate the pulpal temperature rise induced during the polymerization of flowable and non-flowable composites using light-emitting diode (LED) and halogen (quartz-tungsten-halogen) light-curing units (LCUs). Five flowable and three non-flowable composites were examined. Pulpal temperature changes were recorded over 10 min in a sample primary tooth by a thermocouple. A conventional quartz-tungsten-halogen source and two LEDs, one of which was programmable, were used for light curing the resin composites. Three repetitions per material were made for each LCU. There was a wide range of temperature rises among the materials (P Temperature rises ranged between 1.3 degrees C for Filtek Supreme irradiated by low-power LED and 4.5 degrees C for Grandio Flow irradiated by high-power LED. The highest temperature rises were observed with both the LED high-power and soft-start LCUs. The time to reach the exothermic peak varied significantly between the materials (P temperature rise is related to both the radiant energy output from LCUs and the polymerization exotherm of resin composites. A greater potential risk for heat-induced pulp damage might be associated with high-power LED sources. Flowable composites exhibited higher temperature rises than non-flowable materials, because of higher resin contents.

  2. Exothermic dark matter with light mediator after LUX and PandaX-II in 2016

    Science.gov (United States)

    Geng, Chao-Qiang; Huang, Da; Lee, Chun-Hao

    2017-12-01

    Dark matter (DM) direct detections are investigated for models with the following properties: isospin-violating couplings, exothermic scatterings, and/or a light mediator, with the aim to reduce the tension between the CDMS-Si positive signals and other negative searches. In particular, we focus on the non-standard effective operators which could lead to the spin-independent DM-nucleus scatterings with non-trivial dependences on the transfer momentum or DM velocity. As a result, such effective operator choices have the very mild effects on the final fittings. Furthermore, by including the latest constraints from LUX, PandaX-II, XENON1T and PICO-60, we find that, for almost all the considered models, the predicted CDMS-Si signal regions are either severely constrained or completely excluded by the LUX, PandaX-II, XENON1T and PICO-60 data, including the most promising Xe-phobic exothermic DM models with/without a light mediator. Therefore, we conclude that it is very difficult for the present DM framework to explain the CDMS-Si excess.

  3. The effect of the rapid thermal annealing on the interdiffusion and the reaction at the interface of the binary system Cr/Si

    Energy Technology Data Exchange (ETDEWEB)

    Merabet, A. [Laboratoire Physique et Mecanique des Materiaux Metalliques, Departement d' O.M.P., Faculte des Sciences de l' Ingenieur, Universite de Setif, Setif 19000 (Algeria)]. E-mail: merabet_abdelali@yahoo.fr

    2004-12-15

    In order to understand the growth mechanism of the silicides and the effect of the dopant on the electrical activity, a thin layer of chromium (100 nm) is deposited on the single crystal silicon (1 0 0) substrate implanted (10{sup 15} As{sup +} atoms/cm{sup 2}, 100 keV) and non implanted. Afterwards, we performed a rapid thermal annealing in the interval of temperature (450-600 deg. C) for a fixed duration of 45 s. The samples are analyzed by X ray-diffraction (XRD) and Rutherford backscattering spectrometry (RBS). The electrical activity has been investigated by the method of the four-point probes. The analysis of the samples by XRD and RBS showed that the rapid thermal annealing (RTA) leads to a reaction at the interface Cr/Si inducing the formation and the growth of the unique silicide CrSi{sub 2}. It is also established that the kinetics growth of CrSi{sub 2} presents a linear evolution with temperature. This fact shows that the growth is governed by a chemical reaction of the interface. Sheet resistance measurements have been performed to study the electrical behavior for these structures. It is worth to point out that the presence of the implanted arsenic in the single crystal silicon increased the resistance in a significant manner.

  4. The impact of rapid sediment accumulation on pore pressure development and dehydration reactions during shallow subduction in the Gulf of Alaska

    Science.gov (United States)

    Meridth, Lanie N.; Screaton, Elizabeth J.; Jaeger, John M.; James, Stephanie R.; Villaseñor, Tania

    2017-01-01

    In the Gulf of Alaska region, sediment has rapidly accumulated (>1 km/my) in the trench sourced from intensified glaciation in the past ˜1.2 million years. This rapid sediment accumulation increases overburden and should accelerate dehydration of hydrous minerals by insulating the underlying sediment column. These processes have the potential to generate fluid overpressures in the low permeability sediments entering the subduction zone. A 1-D model was developed to simulate dehydration reaction progress and investigate excess pore pressures as sediments approach the trench and are subducted. At the deformation front, simulated temperatures increase by ˜30°C due to the insulating effect of trench sediments. As a result, opal-A begins to react to form quartz while smectite remains mostly unreacted. Loading due to the trench sediments elevates excess pore pressures to ˜30% of lithostatic pressure at the deformation front; however, deformation front excess pore pressures are sensitive to assumptions about the permeability of outer wedge sediments. If the outer wedge sediments are coarse-grained and high-permeability rather than mud-dominated, excess pore pressures are lower but still have an insulating effect. During early subduction, simulated pore pressures continue to rise and reach ˜70% of lithostatic by 60 km landward. The 1-D modeling results suggest that the elevated pore pressures are primarily due to loading and that dehydration reactions are not a significant component of excess pore pressure generation at this margin.

  5. Rapid in vitro splicing of coding sequences from genomic DNA by isothermal recombination reaction-based PCR

    Directory of Open Access Journals (Sweden)

    Wenxuan Chen

    2016-09-01

    Full Text Available Cloning of coding sequence (CDS is an important step for gene function research. Here, we reported a simple and efficient strategy for assembling multiple-exon into an intron-free CDS from genomic DNA (gDNA by an isothermal recombination reaction-based PCR (IRR-PCR method. As an example, a 2067-bp full-length CDS of the anther-specific expression gene OsABCG15, which is composed of seven exons and six introns, was generated by IRR-PCR using genomic DNA of rice leaf as the template. Actually, this approach can be wildly applied to any DNA sequences assembly to achieve CDS cloning, gene fusion and multiple site-directed mutagenesis in functional genomics studies in vitro.

  6. Development of a droplet digital polymerase chain reaction for rapid and simultaneous identification of common foodborne pathogens in soft cheese

    Directory of Open Access Journals (Sweden)

    Paola Cremonesi

    2016-10-01

    Full Text Available Dairy products can harbor various microorganisms (e.g., Campylobacter spp., Salmonella spp., Listeria monocytogenes, verocytotoxin-producing Escherichia coli arising from animal reservoirs, and which can become important sources of foodborne illness. Therefore, early detection of food pathogens is crucial to prevent diseases. We wished to develop an accurate quantitative protocol based on a droplet digital polymerase chain reaction (ddPCR involving eight individual TaqMan™ reactions to detect simultaneously, without selective enrichment, Listeria spp., L. monocytogenes, Salmonella spp., verocytotoxin-producing E. coli and Campylobacter spp. in cheese. ddPCR (a third-generation PCR provides absolute quantification of target DNAs without requirement of a standard curve, which simplifies experimentation and data comparability. The accuracy, specificity and sensitivity of the developed ddPCR system were assessed using purified DNA from 50 reference pathogenic and non-pathogenic strains from international or Italian collections and analyzing soft cheese samples artificially contaminated with serial dilutions (from 4×106 to 4×101 CFU/g of pure cultures from the American Type Culture Collection.Finally, the performance of our ddPCR system was compared by parallel testing with quantitative PCR: it gave higher sensitivity (102 CFU/g for the Listeria spp. assay without the necessity of a standard curve.In conclusion, this is the first ddPCR system developed for simultaneous detection of common foodborne pathogens in cheese using a single set of amplification conditions. As such, it could become a useful strategy for high-throughput screening of microorganisms to evaluate the quality and safety of food products.

  7. Development of a Droplet Digital Polymerase Chain Reaction for Rapid and Simultaneous Identification of Common Foodborne Pathogens in Soft Cheese.

    Science.gov (United States)

    Cremonesi, Paola; Cortimiglia, Claudia; Picozzi, Claudia; Minozzi, Giulietta; Malvisi, Michela; Luini, Mario; Castiglioni, Bianca

    2016-01-01

    Dairy products can harbor various microorganisms (e.g., Campylobacter spp., Salmonella spp., Listeria monocytogenes, verocytotoxin-producing Escherichia coli) arising from animal reservoirs, and which can become important sources of foodborne illness. Therefore, early detection of food pathogens is crucial to prevent diseases. We wished to develop an accurate quantitative protocol based on a droplet digital polymerase chain reaction (ddPCR) involving eight individual TaqMan™ reactions to detect simultaneously, without selective enrichment, Listeria spp., L. monocytogenes, Salmonella spp., verocytotoxin-producing E. coli and Campylobacter spp. in cheese. ddPCR (a "third-generation PCR") provides absolute quantification of target DNAs without requirement of a standard curve, which simplifies experimentation and data comparability. The accuracy, specificity and sensitivity of the developed ddPCR system were assessed using purified DNA from 50 reference pathogenic and non-pathogenic strains from international or Italian collections and analyzing soft cheese samples artificially contaminated with serial dilutions (from 4 × 106 to 4 × 101 CFU/g) of pure cultures from the American Type Culture Collection. Finally, the performance of our ddPCR system was compared by parallel testing with quantitative PCR: it gave higher sensitivity (102 CFU/g for the Listeria spp. assay) without the necessity of a standard curve. In conclusion, this is the first ddPCR system developed for simultaneous detection of common foodborne pathogens in cheese using a single set of amplification conditions. As such, it could become a useful strategy for high-throughput screening of microorganisms to evaluate the quality and safety of food products.

  8. Rapid Detection of Mycobacterium tuberculosis Strains Resistant to Isoniazid and/or Rifampicin: Standardization of Multiplex Polymerase Chain Reaction Analysis.

    Science.gov (United States)

    Collantes, Jimena; Solari, Francesca Barletta; Rigouts, Leen

    2016-12-07

    Drug susceptibility testing using molecular techniques can enhance the identification of drug-resistant Mycobacterium tuberculosis Two multiplex real-time polymerase chain reaction (qPCR) assays were developed to detect the most common resistance-associated mutations to isoniazid (katGS315T, inhA-15C → T), and rifampicin (rpoBH526Y and rpoBS531L). To assess the species specificity of the qPCR, we selected 31 nontuberculous mycobacteria (NTM) reference strains belonging to 17 species from the public collection of mycobacterial cultures (BCCM/ITM). Additionally, we tested 17 isoniazid and/or rifampicin-resistant strains with other mutations in the target genes to assess mutation specificity. The limit of detection for all the targeted mutations was 20 bacilli/reaction. Multiplex 1 showed 90%, 95%, and 100% efficiency for wild type (WT), Mut katGS315T, and Mut rpoBS531L, respectively; whereas Multiplex 2 showed 97%, 94%, and 90% efficiency for WT, Mut inhA-15, and Mut rpoBH526Y, respectively. Three of 17 strains that presented other mutations in the target genes were identified as rifampicin resistant and only 3/31 NTM showed a similar melting temperature to rpoBL531 and/or katGT315 mutants. Thus, our proposed cascade of specific tuberculosis detection followed by drug resistance testing showed sensitivities for katGS315T, rpoBS531L, rpoBH526Y, and inhA-15 detection of 100%, 100%, 100%, and 96%, respectively; and specificities of 98%, 95%, 100%, and 100, respectively. © The American Society of Tropical Medicine and Hygiene.

  9. Ultrasonic-assisted Kabachnik-Fields reaction for rapid fabrication of AIE-active fluorescent organic nanoparticles.

    Science.gov (United States)

    Long, Zi; Liu, Meiying; Jiang, Ruming; Zeng, Guangjiang; Wan, Qing; Huang, Hongye; Deng, Fengjie; Wan, Yiqun; Zhang, Xiaoyong; Wei, Yen

    2017-03-01

    Aggregation-induced emission (AIE)-active fluorescent organic nanoparticles (FNPs) have been extensively explored for fluorescence "turn-on" bio-imaging applications with the unique advantages over conventional FNPs. Transformation of AIE-active molecules into FNPs can greatly expand their biomedical application potential. Here we reported a novel "one-pot" strategy for fabricating AIE-active FNPs through an ultrasonic-assisted, catalysts-free and solvent-free Kabachnik-Fields (KF) reaction for the first time. The KF reaction can be completed within 10min to generate AIE-active PTH-CHO-PEI-DEP FNPs through mixing polyethylenimine and aldehyde group containing AIE dyes and diethyl phosphate. These PTH-CHO-PEI-DEP FNPs were confirmed by proton nuclear magnetic resonance ((1)H NMR) spectroscopy, transmission electron microscopy (TEM) and fluorescence spectroscopy etc. The cell uptake behavior as well as cell viability of PTH-CHO-PEI-DEP FNPs was examined to evaluate their potential for biomedical application. We demonstrated that the amphiphilic α-aminophosphonate polymers could self-assemble into PTH-CHO-PEI-DEP FNPs in aqueous solution and showed excellent water dispersibility. TEM image shows the size of PTH-CHO-PEI-DEP FNPs is 100-200nm. More importantly, the PTH-CHO-PEI-DEP FNPs emit strong green fluorescence and desirable biocompatibility, making them very suitable for biomedical applications. Finally, thus smart FNPs design together with their excellent performance will open a new avenue in the development of FNPs for following biological processes such as carcinogenesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. A tool for rapid screening of direct DNA agents using reaction rates and relative interaction potency: towards screening environmental contaminants for hazard.

    Science.gov (United States)

    Gavina, Jennilee M A; Rubab, Mamoona; Zhang, Huijuan; Zhu, Jiping; Nong, Andy; Feng, Yong-Lai

    2011-11-01

    DNA damage represents a potential biomarker for determining the exposure risk to chemicals and may provide early warning data for identifying chemical hazards to human health. Here, we have demonstrated a simple chromatography-based method that can be used to rapidly screen for the presence of chemical hazards as well as to determine parameters relevant to hazard assessment. In this proof-of-principle study, a simple in vitro system was used to determine the interaction of pollutants and probable carcinogens, phenyl glycidyl ether (PGE), tetrachlorohydroquinone (Cl(4)HQ), methylmethane sulfonate (MMS), styrene-7,8-oxide (SO), and benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), a metabolite of benzo[a]pyrene (B[a]P), with single- and double-stranded DNA probes. Differences in potency and reaction kinetics were studied for chemical and DNA type. A relative interaction potency equivalency (PEQ) of a chemical was determined by ratio of interaction potency of a chemical to BPDE as the reference chemical in the reaction with single- and double-stranded oligodeoxynucleotides. PEQs were found to be BPDE > PGE > SO > MMS > Cl(4)HQ for single-stranded oligodeoxynucleotides while they were found to be BPDE > PGE > Cl(4)HQ > MMS > SO for double-stranded oligodeoxynucleotides. Kinetics evaluation revealed that BPDE reacted with both DNA probes at a significantly faster rate, as compared to the remaining test chemicals. Equilibrium was reached within an hour for BPDE, but required a minimum of 48 h for the remaining chemicals. First-order rate constants were (1.61 ± 0.2) × 10(-3) s(-1) and (3.18 ± 0.4) × 10(-4) s(-1) for reaction of BPDE with double- and single-stranded DNA, respectively. The remaining chemicals possessed rate constants from 2 to 13 × 10(-6) s(-1) with a relative kinetic order for reaction with DNA of BPDE ≫ MMS > SO > PGE > Cl(4)HQ for ds-DNA and BPDE ≫ SO ≈ Cl(4)HQ ≈ MMS > PGE for ss-DNA. We further found that the reaction potency, defined by

  11. Limits of a rapid identification of common Mediterranean sandflies using polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    Azzedine Bounamous

    2014-07-01

    Full Text Available A total of 131 phlebotomine Algerian sandflies have been processed in the present study. They belong to the species Phlebotomus bergeroti, Phlebotomus alexandri, Phlebotomus sergenti, Phlebotomus chabaudi, Phlebotomus riouxi, Phlebotomus perniciosus, Phlebotomus longicuspis, Phlebotomus perfiliewi, Phlebotomus ariasi, Phlebotomus chadlii, Sergentomyia fallax, Sergentomyia minuta, Sergentomyia antennata, Sergentomyia schwetzi, Sergentomyia clydei, Sergentomyia christophersi and Grassomyia dreyfussi. They have been characterised by sequencing of a part of the cytochrome b (cyt b, t RNA serine and NADH1 on the one hand and of the cytochrome C oxidase I of the mitochondrial DNA (mtDNA on the other hand. Our study highlights two sympatric populations within P. sergenti in the area of its type-locality and new haplotypes of P. perniciosus and P. longicuspis without recording the specimens called lcx previously found in North Africa. We tried to use a polymerase chain reaction-restriction fragment length polymorphism method based on a combined double digestion of each marker. These method is not interesting to identify sandflies all over the Mediterranean Basin.

  12. [The rapid specific characterization of clinical isolates of the genus Mycobacterium by the polymerase chain reaction and restriction enzyme analysis].

    Science.gov (United States)

    Cuende, J I; Jaime, M L; Gómez, M T; Del Campo, F; Alba, A; Pérez de Diego, I J

    1995-02-18

    Typing at species level of Mycobacterium is usually performed by microbiological and biochemical methods that require a long time and/or sufficient amount of bacteria. Molecular biology can avoid these problems using different techniques. A colony growth of the following mycobacteria has been analyzed: M. tuberculosis, M. kansasii, M. avium, M. intracellulare, M. gordonae, M. phlei, M. aurum, M. fortuitum, M. flavescens, M. marinum, M. xenopi, M. nonchromogenicum, M. terrae and M. chelonei. Strains were grown in Löwenstein-Jensen medium. DNA was obtained by proteolytic digestion and fenol extraction. The 16S rRNA gen was amplified by polymerase chain reaction (PCR) and the amplification was digested by HaeIII, HpaII, RsaI and AluI restriction enzymes. Restriction fragment patterns were analyzed by agarose gel electrophoresis and UV transillumination. The combination of the patterns obtained with HpaII and RsaI was sufficient to generate 13 different combined ones. The patterns of M. intracellulare and M. avium were the same. PCR and restriction enzyme analysis is an useful method for typing at species level of clinical isolates of mycobacteria.

  13. A new way to rapidly create functional, fluorescent fusion proteins: random insertion of GFP with an in vitro transposition reaction

    Directory of Open Access Journals (Sweden)

    Jakobsdottir Klara B

    2002-06-01

    Full Text Available Abstract Background The jellyfish green fluorescent protein (GFP can be inserted into the middle of another protein to produce a functional, fluorescent fusion protein. Finding permissive sites for insertion, however, can be difficult. Here we describe a transposon-based approach for rapidly creating libraries of GFP fusion proteins. Results We tested our approach on the glutamate receptor subunit, GluR1, and the G protein subunit, αs. All of the in-frame GFP insertions produced a fluorescent protein, consistent with the idea that GFP will fold and form a fluorophore when inserted into virtually any domain of another protein. Some of the proteins retained their signaling function, and the random nature of the transposition process revealed permissive sites for insertion that would not have been predicted on the basis of structural or functional models of how that protein works. Conclusion This technique should greatly speed the discovery of functional fusion proteins, genetically encodable sensors, and optimized fluorescence resonance energy transfer pairs.

  14. Microfabricated Renewable Beads-Trapping/Releasing Flow Cell for Rapid Antigen-Antibody Reaction in Chemiluminescent Immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Zhifeng; Shao, Guocheng; Wang, Jun; Lu, Donglai; Wang, Wanjun; Lin, Yuehe

    2011-04-01

    A filter pillar-array microstructure was coupled with a pneumatic micro-valve to fabricate a reusable miniaturized beads-trapping/releasing flow cell, in which trapping and releasing beads can be conveniently realized by switching the micro-valve. This miniaturized device was suitable to construct automatic fluidic system for “renewable surface analysis”. The renewable surface strategy based on pneumatic micro-valve enabled capture of beads in beads chamber prior to each assay, and release of the used beads after the assay. Chemiluminescent competitive immunoassay of 3,5,6-trichloropyridinol (TCP) was performed as a model to demonstrate the application potential of this reusable miniaturized flow cell. The whole fluidic assay process including beads trapping, immuno-binding, beads washing, beads releasing and signal collection could be completed in 10 min. Immunoassay of TCP using this miniaturized device showed a linear range of 0.20-70 ng/mL with a limit of detection of 0.080 ng/mL. The device had been successfully used for detection of TCP spiked in rat serum with average recovery of 97%. This investigation provides a rapid, sensitive, reusable, low-cost and automatic miniaturized device for solid-phase biochemical analysis for various purposes.

  15. Efficient fabrication of nanoporous si and Si/Ge enabled by a heat scavenger in magnesiothermic reactions

    National Research Council Canada - National Science Library

    Luo, Wei; Wang, Xingfeng; Meyers, Colin; Wannenmacher, Nick; Sirisaksoontorn, Weekit; Lerner, Michael M; Ji, Xiulei

    2013-01-01

    Magnesiothermic reduction can directly convert SiO2 into Si nanostructures. Despite intense efforts, efficient fabrication of highly nanoporous silicon by Mg still remains a significant challenge due to the exothermic reaction nature...

  16. Application of real time polymerase chain reaction targeting kex 1 gene & its comparison with the conventional methods for rapid detection of Pneumocystis jirovecii in clinical specimens

    Directory of Open Access Journals (Sweden)

    Mani Revathy

    2014-01-01

    Full Text Available Background & objectives: As there are no standard laboratory techniques for the rapid detection of Pneumocystis jirovecii in India, this study was undertaken to evaluate and establish an optimal and rapid technique for the detection of P. jirovecii by comparing three different techniques - staining technique, application of a real time polymerase chain reaction (RT-PCR targeting kex 1 gene and application of nested PCR targeting mitochondrial large subunit (mtLSU gene for rapid detection of P. jirovecii in HIV positive patients. Methods: One hundred and fifty sputum specimens from HIV positive (n = 75 and HIV negative (n = 75 patients were subjected to three different techniques -KOH/Calcoflour and Grocott methanamine silver staining (GMS, RT-PCR targeting kex1 gene, PCR targeting mtLSU region followed by DNA sequencing and BLAST analysis. Results: Among the 75 HIV positive patients, P. jirovecii was detected in 19 (25.33% patients by the staining techniques, and in 23 (30.65% patients each by PCR targeting mtLSU region and by RT- PCR targeting kex1 gene of P. jirovecii. PCR based DNA sequencing targeting mtLSU region revealed 97-100 per cent sequence homology with P. jirovecii sequences in GenBank. Interpretation & conclusions: Of the three techniques for detection of P. jirovecii evaluated in this study, false negativity was found to be more in staining technique and it also required high technical expertise to interpret the result. Both nested PCR and RT-PCR were reliable and equally sensitive, in rapid detection of P. jirovecii, but RT-PCR technique also generated the copy numbers for knowing the severity of infection.

  17. Electrical characteristics and interfacial reactions of rapidly annealed Pt/Ru Schottky contacts on n-type GaN

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, N.N.K.; Rajagopal Reddy, V. [Department of Physics, Sri Venkateswara University, Tirupati (India); Choi, C.J. [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju (Korea, Republic of)

    2011-07-15

    The electrical properties and interfacial reactions of Pt/Ru Schottky contacts on n-type gallium nitride (GaN) have been investigated as a function of annealing temperature. The calculated Schottky barrier height (SBH) of the as-deposited Pt/Ru Schottky contact is found to be 0.69 eV current-voltage (I-V) and 0.76 eV capacitance-voltage (C-V). Experimental results showed that the SBHs are increased on increasing the annealing temperature. When the contact is annealed at 600 C, a maximum barrier height is obtained and the corresponding values are 0.87 eV (I-V) and 0.99 eV (C-V). The Norde method was also employed to extract the barrier height of Pt/Ru Schottky contacts and the values are 0.70 and 0.86 eV for the samples as-deposited and annealed at 600 C, which are in good agreement with those obtained from the I-V measurement. Shifts of the surface Fermi level are measured with the change in position of the Ga 2p core level peak. Based on the X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) studies, the formation of gallide phases at the Ru/Pt/n-GaN interface could be the reason for the increase in SBH at elevated temperatures. Atomic force microscopy (AFM) results showed that the surface morphology of the Pt/Ru Schottky contact did not change significantly even after annealing at 600 C. These results point out that a Pt/Ru Schottky contact may be a suitable candidate for the fabrication of GaN-based high-temperature device applications. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Rapid process for manufacturing of aluminum nitride powder

    Energy Technology Data Exchange (ETDEWEB)

    Weimer, A.W.; Cochran, G.A.; Eisman, G.A.; Henley, J.P.; Hook, B.D.; Mills, L.K. [Dow Chemical Co., Midland, MI (United States). Ceramics and Advanced Materials Research; Guiton, T.A.; Knudsen, A.K.; Nicholas, R.N.; Volmering, J.E.; Moore, W.G. [Dow Chemical Co., Midland, MI (United States). Advanced Ceramics Lab.

    1994-01-01

    A rapid, direct nitridation process for the manufacture of sinterable aluminum nitride (AIN) powder was developed at the pilot scale. Atomized aluminum metal and nitrogen gas were heated and reacted rapidly to synthesize AIN while they passed through the reaction zone of a transport flow reactor. The heated walls of the reactor simultaneously initiated the reaction and removed the generated heat to control the exotherm. Several variations of the process were required to achieve high conversion and reduce wall deposition of the product. The fine AIN powder produced did not require a postreaction grinding step to reduce particle size. However, a secondary heat treatment, following a mild milling step to expose fresh surface, was necessary to ensure complete conversion of the aluminum. In some instances, a final air classification step to remove large particles was necessary to promote densification by pressure less sintering. The AIN powder produced was pressure less sintered with 3 wt% yttria to fabricate fully dense parts which exhibited high thermal conductivity. The powder was shown to be less sinterable than commercially available carbothermally produced powders

  19. Luminous exothermic hollow optical elements for enhancement of biofilm growth and activity.

    Science.gov (United States)

    Zhong, Nianbing; Zhao, Mingfu; Zhong, Lianchao; Li, Shan; Luo, Binbin; Tang, Bin; Song, Tao; Shi, Shenghui; Hu, Xinyu; Xin, Xin; Wu, Ruohua; Cen, Yanyan; Wang, Zhengkun

    2017-03-20

    In this work, we present a luminous-exothermic hollow optical element (LEHOE) that performs spectral beam splitting in the visible spectral range for the enhancement of biofilm growth and activity. The LEHOE is composed of a four-layer structure with a fiber core (air), cladding (SiO2), coating I (LaB6 film), and coating II (SiO2-Agarose-Medium film). To clarify the physical, optical and photothermal conversion properties of the LEHOE, we determined the surface morphology and composition of the coating materials, and examined the luminous intensity and heating rate at the LEHOE surface. The biofilm activity on the biocompatible LEHOE is far greater than that of commercial fibers, and the biofilm weight on the LEHOE is 4.5 × that of the uncoated hollow optical element.

  20. Exothermic or Endothermic Decomposition of Disubstituted Tetrazoles Tuned by Substitution Fashion and Substituents.

    Science.gov (United States)

    Jia, Yu-Hui; Yang, Kai-Xiang; Chen, Shi-Lu; Huang, Mu-Hua

    2018-01-11

    Nitrogen-rich compounds such as tetrazoles are widely used as candidates in gas-generating agents. However, the details of the differentiation of the two isomers of disubstituted tetrazoles are rarely studied, which is very important information for designing advanced materials based on tetrazoles. In this article, pairs of 2,5- and 1,5-disubstituted tetrazoles were carefully designed and prepared for study on their thermal decomposition behavior. Also, the substitution fashion of 2,5- and 1,5- and the substituents at C-5 position were found to affect the endothermic or exothermic properties. This is for the first time to the best of our knowledge that the thermal decomposition properties of different tetrazoles could be tuned by substitution ways and substitute groups, which could be used as a useful platform to design advanced materials for temperature-dependent rockets. The aza-Claisen rearrangement was proposed to understand the endothermic decomposition behavior.

  1. Rapid "breath-print" of liver cirrhosis by proton transfer reaction time-of-flight mass spectrometry. A pilot study.

    Directory of Open Access Journals (Sweden)

    Filomena Morisco

    Full Text Available UNLABELLED: The aim of the present work was to test the potential of Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS in the diagnosis of liver cirrhosis and the assessment of disease severity by direct analysis of exhaled breath. Twenty-six volunteers have been enrolled in this study: 12 patients (M/F 8/4, mean age 70.5 years, min-max 42-80 years with liver cirrhosis of different etiologies and at different severity of disease and 14 healthy subjects (M/F 5/9, mean age 52.3 years, min-max 35-77 years. Real time breath analysis was performed on fasting subjects using a buffered end-tidal on-line sampler directly coupled to a PTR-ToF-MS. Twelve volatile organic compounds (VOCs resulted significantly differently in cirrhotic patients (CP compared to healthy controls (CTRL: four ketones (2-butanone, 2- or 3- pentanone, C8-ketone, C9-ketone, two terpenes (monoterpene, monoterpene related, four sulphur or nitrogen compounds (sulfoxide-compound, S-compound, NS-compound, N-compound and two alcohols (heptadienol, methanol. Seven VOCs (2-butanone, C8-ketone, a monoterpene, 2,4-heptadienol and three compounds containing N, S or NS resulted significantly differently in compensate cirrhotic patients (Child-Pugh A; CP-A and decompensated cirrhotic subjects (Child-Pugh B+C; CP-B+C. ROC (Receiver Operating Characteristic analysis was performed considering three contrast groups: CP vs CTRL, CP-A vs CTRL and CP-A vs CP-B+C. In these comparisons monoterpene and N-compound showed the best diagnostic performance. CONCLUSIONS: Breath analysis by PTR-ToF-MS was able to distinguish cirrhotic patients from healthy subjects and to discriminate those with well compensated liver disease from those at more advanced severity stage. A breath-print of liver cirrhosis was assessed for the first time.

  2. RADMAP: Simple probes for rapid assessment of complex reactivity: A method and case studies on the reaction of hydrogen atoms with unsaturated organic molecules.

    Science.gov (United States)

    Long, Andrew K; Fawcett, Jason A; Clyburne, Jason A C; Pye, Cory C

    2016-03-01

    RADMAP, an open source program, allows for rapid analysis and visualization of the earliest stages of reactions between any molecule and a monoatomic probe (i.e., H*, H(+), H(-), Br*, or any other monoatomic species) using ab initio methods. This program creates non-planar potential energy surfaces of the initial interaction between a molecule of interest and the monoatomic probe. These surfaces can be used to both predict the site of addition as well as provide a qualitative estimate for the relative proportion of the formation of adducts; therefore, it gives insight into both the reactivity and the kinetic stability of a molecule. The program presents a way to quickly predict the number of signals anticipated in transverse field muon spin resonance spectra as well as their relative intensities. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Rapid synthesis of graphitic carbon nitride powders by metathesis reaction between CaCN{sub 2} and C{sub 2}Cl{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Pang Linlin [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan, 250061 (China); Carbon Fiber Engineering Research Center of Shandong Province, Shandong University, Jinan 250061 (China); Bi Jianqiang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan, 250061 (China); Bai Yujun [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan, 250061 (China) and Carbon Fiber Engineering Research Center of Shandong Province, Shandong University, Jinan 250061 (China)], E-mail: byj97@126.com; Qi Yongxin [Carbon Fiber Engineering Research Center of Shandong Province, Shandong University, Jinan 250061 (China); Zhu Huiling [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan, 250061 (China); Carbon Fiber Engineering Research Center of Shandong Province, Shandong University, Jinan 250061 (China); Wang Chengguo; Wu Jiwei [Carbon Fiber Engineering Research Center of Shandong Province, Shandong University, Jinan 250061 (China); Lu Chengwei [Department of Equipment, Shandong University of Science and Technology, Jinan 250031 (China)

    2008-12-20

    Carbon nitride powders were rapidly synthesized at low temperature via the chemical metathesis reaction between CaCN{sub 2} and C{sub 2}Cl{sub 6}. X-ray diffraction results confirm the formation of crystalline graphitic carbon nitride. Besides the dominant morphology of nanoparticles, flakes, nanorods, hollow and solid spheres can be observed by transmission electron microscopy. The absorption peaks of C-N, C=N and s-triazine rings, as well as the absence of C{identical_to}N peak in the infrared spectra, further verify the formation of graphite-like sp{sup 2}-bonded structure with planar networks. Elemental analysis gives an atomic ratio of N/C around 0.3. X-ray photoelectron spectra exhibit the existence of chemical bonding between C and N.

  4. Method for producing bio-fuel that integrates heat from carbon-carbon bond-forming reactions to drive biomass gasification reactions

    Science.gov (United States)

    Cortright, Randy D [Madison, WI; Dumesic, James A [Verona, WI

    2012-04-10

    A low-temperature catalytic process for converting biomass (preferably glycerol recovered from the fabrication of bio-diesel) to synthesis gas (i.e., H.sub.2/CO gas mixture) in an endothermic gasification reaction is described. The synthesis gas is used in exothermic carbon-carbon bond-forming reactions, such as Fischer-Tropsch, methanol, or dimethylether syntheses. The heat from the exothermic carbon-carbon bond-forming reaction is integrated with the endothermic gasification reaction, thus providing an energy-efficient route for producing fuels and chemicals from renewable biomass resources.

  5. Method for producing bio-fuel that integrates heat from carbon-carbon bond-forming reactions to drive biomass gasification reactions

    Science.gov (United States)

    Cortright, Randy D [Madison, WI; Dumesic, James A [Verona, WI

    2011-01-18

    A low-temperature catalytic process for converting biomass (preferably glycerol recovered from the fabrication of bio-diesel) to synthesis gas (i.e., H.sub.2/CO gas mixture) in an endothermic gasification reaction is described. The synthesis gas is used in exothermic carbon-carbon bond-forming reactions, such as Fischer-Tropsch, methanol, or dimethylether syntheses. The heat from the exothermic carbon-carbon bond-forming reaction is integrated with the endothermic gasification reaction, thus providing an energy-efficient route for producing fuels and chemicals from renewable biomass resources.

  6. Rapid detection and quantification of Ebola Zaire virus by one-step real-time quantitative reverse transcription-polymerase chain reaction.

    Science.gov (United States)

    Ro, Young-Tae; Ticer, Anysha; Carrion, Ricardo; Patterson, Jean L

    2017-04-01

    Given that Ebola virus causes severe hemorrhagic fever in humans with mortality rates as high as 90%, rapid and accurate detection of this virus is essential both for controlling infection and preventing further transmission. Here, a one-step qRT-PCR assay for rapid and quantitative detection of an Ebola Zaire strain using GP, VP24 or VP40 genes as a target is introduced. Routine assay conditions for hydrolysis probe detection were established from the manufacturer's protocol used in the assays. The analytical specificity and sensitivity of each assay was evaluated using in vitro synthesized viral RNA transcripts. The assays were highly specific for the RNA transcripts, no cross-reactivity being observed among them. The limits of detection of the assays ranged from 102 to 103 copies per reaction. The assays were also evaluated using viral RNAs extracted from cell culture-propagated viruses (Ebola Zaire, Sudan and Reston strains), confirming that they are gene- and strain-specific. The RT-PCR assays detected viral RNAs in blood samples from virus-infected animal, suggesting that they can be also a useful method for identifying Ebola virus in clinical samples. © 2017 The Societies and John Wiley & Sons Australia, Ltd.

  7. Rapid mitochondrial DNA typing using restriction enzyme digestion of polymerase chain reaction amplicons followed by capillary electrophoresis separation with laser-induced fluorescence detection.

    Science.gov (United States)

    Butler, J M; Wilson, M R; Reeder, D J

    1998-01-01

    The polymorphic control region of mitochondrial DNA (mtDNA) is becoming more commonly used in forensic applications to differentiate among individuals in a population. Two hypervariable regions (HV1 and HV2) are often sequenced following amplification of the mtDNA via the polymerase chain reaction (PCR). More rapid screening assays would reduce both the effort and the expense of comparing two samples. A methodology has been developed that first uses restriction endonuclease digestion of the PCR-amplified mtDNA using RsaI and MnlI and then capillary electrophoresis (CE) to separate and size the PCR-RFLP fragments. This rapid procedure offers an alternative method for screening of polymorphisms in amplified mtDNA samples. In addition, the presence of a T-->C transition at position 16189, which gives rise to the so-called "C-stretch" in HV1, may be predicted from the presence of nonspecific PCR products in the CE results.

  8. Rapid characterization of dry cured ham produced following different PDOs by proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS).

    Science.gov (United States)

    Del Pulgar, José Sánchez; Soukoulis, Christos; Biasioli, Franco; Cappellin, Luca; García, Carmen; Gasperi, Flavia; Granitto, Pablo; Märk, Tilmann D; Piasentier, Edi; Schuhfried, Erna

    2011-07-15

    In the present study, the recently developed proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS) technique was used for the rapid characterization of dry cured hams produced according to 4 of the most important Protected Designations of Origin (PDOs): an Iberian one (Dehesa de Extremadura) and three Italian ones (Prosciutto di San Daniele, Prosciutto di Parma and Prosciutto Toscano). In total, the headspace composition and respective concentration for nine Spanish and 37 Italian dry cured ham samples were analyzed by direct injection without any pre-treatment or pre-concentration. Firstly, we show that the rapid PTR-ToF-MS fingerprinting in conjunction with chemometrics (Principal Components Analysis) indicates a good separation of the dry cured ham samples according to their production process and that it is possible to set up, using data mining methods, classification models with a high success rate in cross validation. Secondly, we exploited the higher mass resolution of the new PTR-ToF-MS, as compared with standard quadrupole based versions, for the identification of the exact sum formula of the mass spectrometric peaks providing analytical information on the observed differences. The work indicates that PTR-ToF-MS can be used as a rapid method for the identification of differences among dry cured hams produced following the indications of different PDOs and that it provides information on some of the major volatile compounds and their link with the implemented manufacturing practices such as rearing system, salting and curing process, manufacturing practices that seem to strongly affect the final volatile organic profile and thus the perceived quality of dry cured ham. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Incidents of chemical reactions in cell equipment

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, N.M.; Barlow, C.R. [Uranium Enrichment Organization, Oak Ridge, TN (United States)

    1991-12-31

    Strongly exothermic reactions can occur between equipment structural components and process gases under certain accident conditions in the diffusion enrichment cascades. This paper describes the conditions required for initiation of these reactions, and describes the range of such reactions experienced over nearly 50 years of equipment operation in the US uranium enrichment program. Factors are cited which can promote or limit the destructive extent of these reactions, and process operations are described which are designed to control the reactions to minimize equipment damage, downtime, and the possibility of material releases.

  10. DFT study of the reactions of Mo and Mo with CO2 in gas phase

    Indian Academy of Sciences (India)

    row metal reacting with CO2. The minimum energy reaction path is found to involve the spin inversion in the different reaction steps. This potential energy curve-crossing dramati- cally affects reaction exothermic. The present results show that ...

  11. A novel high performance stopped-flow apparatus equipped with a special constructed mixing chamber containing a plunger under inert condition with a very short dead-time to investigate very rapid reactions

    Directory of Open Access Journals (Sweden)

    Sayyed Mostafa Habibi Khorassani

    2015-11-01

    Full Text Available The present work set out to establish a novel stopped-flow instrument equipped with a special constructed mixing chamber containing a plunger to enable a kinetic study of the very rapid reactions under a dry inert atmosphere glove bag, in particular, for the reactions are sensitive to moisture or air. A stopped-flow spectrophotometer is essentially a conventional spectrophotometer with the addition of a system for rapid mixing of solutions. The purpose of this work is to describe the fabrication and evaluation of specially constructed and in-expensive stopped-flow system. The evaluation includes determination of the dead-time, relative mixing efficiency, and the measurement of known rate constants. Herein, a dead-time of about 3.4 ms was determined in the final modified construction of the stopped-flow apparatus in order to investigate the rapid initial during which some form of reaction intermediate is presented to be formed.

  12. System and method for regeneration and recirculation of a reducing agent using highly exothermic reactions induced by mixed industrial slags

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Jinichiro; Bennett, James P.; Nakano, Anna

    2017-12-12

    Embodiments relate to systems and methods for regenerating and recirculating a CO, H.sub.2 or combinations thereof utilized for metal oxide reduction in a reduction furnace. The reduction furnace receives the reducing agent, reduces the metal oxide, and generates an exhaust of the oxidized product. The oxidized product is transferred to a mixing vessel, where the oxidized product, a calcium oxide, and a vanadium oxide interact to regenerate the reducing agent from the oxidized product. The regenerated reducing agent is transferred back to the reduction furnace for continued metal oxide reductions.

  13. Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study.

    Science.gov (United States)

    Janz, V; Schoon, J; Morgenstern, C; Preininger, B; Reinke, S; Duda, G; Breitbach, A; Perka, C F; Geissler, S

    2018-01-01

    The objective of this study was to develop a test for the rapid (within 25 minutes) intraoperative detection of bacteria from synovial fluid to diagnose periprosthetic joint infection (PJI). The 16s rDNA test combines a polymerase chain reaction (PCR) for amplification of 16s rDNA with a lateral flow immunoassay in one fully automated system. The synovial fluid of 77 patients undergoing joint aspiration or primary or revision total hip or knee surgery was prospectively collected. The cohort was divided into a proof-of-principle cohort (n = 17) and a validation cohort (n = 60). Using the proof-of-principle cohort, an optimal cut-off for the discrimination between PJI and non-PJI samples was determined. PJI was defined as detection of the same bacterial species in a minimum of two microbiological samples, positive histology, and presence of a sinus tract or intra-articular pus. The 16s rDNA test proved to be very robust and was able to provide a result in 97% of all samples within 25 minutes. The 16s rDNA test was able to diagnose PJI with a sensitivity of 87.5% and 82%, and a specificity of 100% and 89%, in the proof-of-principle and validation cohorts, respectively. The microbiological culture of synovial fluid achieved a sensitivity of 80% and a specificity of 93% in the validation cohort. The 16s rDNA test offers reliable intraoperative detection of all bacterial species within 25 minutes with a sensitivity and specificity comparable with those of conventional microbiological culture of synovial fluid for the detection of PJI. The 16s rDNA test performance is independent of possible blood contamination, culture time and bacterial species. Cite this article : V. Janz, J. Schoon, C. Morgenstern, B. Preininger, S. Reinke, G. Duda, A. Breitbach, C. F. Perka, S. Geissler. Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study. Bone Joint Res 2018;7:12-19. DOI: 10

  14. A sensitive and a rapid multiplex polymerase chain reaction for the identification of Candida species in concentrated oral rinse specimens in patients with diabetes.

    Science.gov (United States)

    Sampath, Asanga; Weerasekera, Manjula; Gunasekara, Chinthika; Dilhari, Ayomi; Bulugahapitiya, Uditha; Fernando, Neluka

    2017-03-01

    Oral candidiasis is being frequently recognized in patients with diabetes, and is associated with multiple pathogens including Candida albicans, Candida parapsilosis, Candida glabrata and Candida tropicalis. The aim of this study was to evaluate a usefulness of a Multiplex Polymerase Chain Reaction as a rapid diagnostic tool for identification of four oral Candida pathogens in patients with diabetes. A multiplex PCR was optimized to identify four Candida species in concentrated oral rinse samples. Common reverse primer, ITS4 and four species-specific forward primers targeting ITS1 and ITS2 regions of yeast genome were used. Species-specific single amplicon were detected by agarose gel electrophoresis. Performance efficacy of multiplex PCR was compared with phenotypic identification. Out of 100 oral rinse samples, 72 were culture positive and of these 43 were at risk of oral Candida infection (>600cfu/ml). Multiple Candida species including C. albicans, C. parapsilosis and C. tropicalis were identified in 22 samples which had risk of oral Candida infection. In total, 85 patients were positive for Candida by multiplex PCR and of them 49 had multiple Candida species. All 43 colonized specimens were also positive by multiplex PCR. C. albicans was the most predominant organism (75/85) followed by C. parapsilosis (47/85), C. tropicalis (17/85) and C. glabrata (6/85). In specimens with multiple species, the two most common organisms were C. albicans and C. parapsilosis. Multiplex PCR yielded a sensitivity of 10 Candida cells/ml of oral rinse sample. Multiplex PCR is found to be rapid, sensitive and specific than phenotypic identification methods in discriminating multiple Candida species in oral rinse specimens.

  15. Impact of rapid methicillin-resistant Staphylococcus aureus polymerase chain reaction testing on mortality and cost effectiveness in hospitalized patients with bacteraemia: a decision model.

    Science.gov (United States)

    Brown, Jack; Paladino, Joseph A

    2010-01-01

    Patients hospitalized with Staphylococcus aureus bacteraemia have an unacceptably high mortality rate. Literature available to date has shown that timely selection of the most appropriate antibacterial may reduce mortality. One tool that may help with this selection is a polymerase chain reaction (PCR) assay that distinguishes methicillin (meticillin)-resistant S. aureus (MRSA) from methicillin-susceptible S. aureus (MSSA) in less than 1 hour. To date, no information is available evaluating the impact of this PCR technique on clinical or economic outcomes. To evaluate the effect of a rapid PCR assay on mortality and economics compared with traditional empiric therapy, using a literature-derived model. A literature search for peer-reviewed European (EU) and US publications regarding treatment regimens, outcomes and costs was conducted. Information detailing the rates of infection, as well as the specificity and sensitivity of a rapid PCR assay (Xpert MRSA/SA Blood Culture PCR) were obtained from the peer-reviewed literature. Sensitivity analysis varied the prevalence rate of MRSA from 5% to 80%, while threshold analysis was applied to the cost of the PCR test. Hospital and testing resource consumption were valued with direct medical costs, adjusted to year 2009 values. Adjusted life-years were determined using US and WHO life tables. The cost-effectiveness ratio was defined as the cost per life-year saved. Incremental cost-effectiveness ratios (ICERs) were calculated to determine the additional cost necessary to produce additional effectiveness. All analyses were performed using TreeAge Software (2008). The mean mortality rates were 23% for patients receiving empiric vancomycin subsequently switched to semi-synthetic penicillin (SSP) for MSSA, 36% for patients receiving empiric vancomycin treatment for MRSA, 59% for patients receiving empiric SSP subsequently switched to vancomycin for MRSA and 12% for patients receiving empiric SSP for MSSA. Furthermore, with an

  16. Using real-time polymerase chain reaction as an alternative rapid method for enumeration of colony count in liveBrucellavaccines.

    Science.gov (United States)

    Shell, Waleed S; Sayed, Mahmoud L; Samy, A A; Al-Sadek, Ghada Mohamed; El-Hamid, Gina Mohamed Mohamed Abd; Ali, Abdel Hakam M

    2017-06-01

    Brucellosis is a major bacterial zoonosis of global importance affecting a range of animal species and man worldwide. It has economic, public health, and bio-risk importance. Control and prevention of animal brucellosis mainly depend on accurate diagnostic tools and implementation of effective and safe animal vaccination program. There are three types of animal Brucella live vaccines - Brucella melitensis Rev-1 vaccine, Brucella abortus S19, and B . abortus RB51. Evaluation of these vaccines depends mainly on enumeration of Brucella viable count. At present, used colony count method is time consuming, costly and requires especial skills. Hence, the aim of this study is to use and standardize real-time polymerase chain reaction (RT-PCR) as an alternative, quantitative, sensitive, and rapid method to detect the colony count of Brucella in live Brucella vaccine. Four batches of different live Brucella vaccines were evaluated using of conventional bacterial count and RT-quantitative PCR (RT-qPCR) using BSCP31 gene specific primers and probe. Standard curve was generated from DNA template extracted from 10-fold serial dilution of living B. abortus RB51 vaccine to evaluate the sensitivity of RT-qPCR. Results revealed that three batches of living Brucella vaccines were acceptable for Brucella colony count when traditional bacterial enumeration method was used. Results of RT-qPCR were identical to that of conventional bacterial count. Results concluded that RT-qPCR was relatively sensitive compared to traditional bacterial colony count of these vaccines.

  17. Accuracy of a rapid real-time polymerase chain reaction assay for diagnosis of group B Streptococcus colonization in a cohort of HIV-infected pregnant women.

    Science.gov (United States)

    Gouvea, Maria Isabel S; Joao, Esau C; Teixeira, Maria de Lourdes B; Read, Jennifer S; Fracalanzza, Sergio E L; Souza, Claudia T V; Souza, Maria José de; Torres Filho, Helio M; Leite, Cassiana C F; do Brasil, Pedro E A A

    2017-05-01

    There are limited data regarding Xpert performance to detect Group B Streptococcus (GBS) in HIV-infected pregnant women. We evaluated the accuracy of a rapid real-time polymerase chain reaction (PCR) test in a cohort of HIV-infected women. At 35-37 weeks of pregnancy, a pair of combined rectovaginal swabs were collected for two GBS assays in a cohort of sequentially included HIV-infected women in Rio de Janeiro: (1) culture; and (2) real-time PCR assay [GeneXpert GBS (Cepheid, Sunnyvale, CA)]. Using culture as the reference, sensitivity, specificity, positive and negative-likelihood ratios were estimated. From June 2012 to February 2015, 337 pregnant women met inclusion criteria. One woman was later excluded, due to failure to obtain a result in the index test; 336 were included in the analyses. The GBS colonization rate was 19.04%. Sensitivity and specificity of the GeneXpert GBS assay were 85.94% (95% CI: 75.38-92.42) and 94.85% (95% CI: 91.55-96.91), respectively. Positive and negative predictive values were 79.71% (95% CI: 68.78-87.51) and 96.63% (95% CI: 93.72-98.22), respectively. GeneXpert GBS is an acceptable test for the identification of GBS colonization in HIV-infected pregnant women and represents a reasonable option to detect GBS colonization in settings where culture is not feasible.

  18. Detection of 2-deoxy-D-ribose radicals generated by the reaction with the hydroxyl radical using a rapid flow-ESR method.

    Science.gov (United States)

    Ohashi, Yasunori; Yoshioka, Hisashi; Yoshioka, Hiroe

    2002-04-01

    ESR spectrum of the short-lived radicals derived from 2-deoxy-D-ribose by the reaction with the hydroxyl radical (HO*) was measured using a rapid flow method. A dielectric mixing resonator was used for the measurement, which made it possible to measure the highly sensitive ESR spectra of the radicals with a lifetime of the order of milliseconds. A complex spectrum was obtained and the spectral simulation was done to show that it was the superposition of the signals due to five radicals (I-V). Three of them were those formed by the dehydrogenation with the HO* at C-1 (I), C-3 (II), and C-4 (III) positions of the 2-deoxy-D-ribose molecule. The other two (IV and V) were carbonyl-conjugated radicals formed by the elimination of a water molecule from III and II. The results showed that dehydrogenation occurred randomly at the positions where hydroxyl groups are attached, but the most preferred position was C-3 and the radical position moved from C-3 to C-4 by the elimination of water molecule.

  19. Simultaneous and rapid differential diagnosis of Mycoplasma genitalium and Ureaplasma urealyticum based on a polymerase chain reaction-restriction fragment length polymorphism

    Directory of Open Access Journals (Sweden)

    R Mirnejad

    2011-01-01

    Full Text Available Objectives: The aim of this investigation was to simultaneously detect and differentiate Mycoplasma genitalium and Ureaplasma urealyticum in female patients suffering from genital complications by polymerase chain reaction (PCR-restriction fragment length polymorphism (RFLP. Materials and Methods : Genital swabs were taken from 210 patients. They were transported to the laboratory in phosphate-buffered saline. For PCR, samples were analysed with genus-specific MyUu-R and MyUu-F primers. This primer set, which was originally designed in our laboratory, amplified a 465 bp fragment (M. genitalium and a 559 bp fragment (U. urealyticum. Samples containing a band of the expected sizes for the Mycoplasma strains were subjected to digestion with a restriction endonuclease enzyme of TaqI and Cac8I. Results: Of the 210 samples, a total of 100 (47.6% samples were found to be positive for Mycoplasmas (seven M. genitalium isolates, 3.3%; and 89 U. urealyticum isolates, 42.4%, and coinfections with both species were detected in four samples (1.9%. The PCR-RFLP results showed that M. genitalium and U. urealyticum are different by enzyme patterns. Conclusion: PCR-RFLP offers a rapid and easily applicable protocol to simultaneous detection and differentiation of M. genitalium and U. urealyticum from clinical samples when specific primers and restriction enzymes are used.

  20. Rapid and sensitive detection of Mycoplasma synoviae by an insulated isothermal polymerase chain reaction-based assay on a field-deployable device.

    Science.gov (United States)

    Kuo, Hung-Chih; Lo, Dan-Yuan; Chen, Chiou-Lin; Tsai, Yun-Long; Ping, Jia-Fong; Lee, Chien-Hsien; Lee, Pei-Yu Alison; Chang, Hsiao-Fen Grace

    2017-01-01

    Mycoplasma synoviae (MS), causing respiratory diseases, arthritis, and eggshell apex abnormalities in avian species, is an important pathogen in the poultry industry. Implementation of a biosecurity plan is important in MS infection management. Working on a field-deployable POCKIT™ device, an insulated isothermal polymerase chain reaction (iiPCR) assay has a potential for timely MS detection on the farm. The MS iiPCR assay had limit of detection 95% of about 9 genome equivalents by testing serial dilutions of a standard DNA. The detection endpoint of the assay for detection of MS genomic DNA was comparable to a reference real-time PCR. The assay did not crossreact with other important avian pathogens, including avian reovirus, Mycoplasma gallisepticum, Staphylococcus aureus, Escherichia coli, Pasteurella multocida, and Salmonella Pullorum. When 92 synovial fluid and respiratory tract swab samples collected from chickens, turkeys, and geese suspected of MS infection were tested, the clinical performance of the MS iiPCR had 97.8% agreement (Cohen's kappa value, 0.95) with that of the reference real-time PCR. In conclusion, the MS iiPCR/POCKIT™ system, working with field-deployable manual or automatic nucleic acid extraction methods, has potential to serve as a rapid and sensitive on-site tool to facilitate timely detection of MS. © The Author 2016. Published by Oxford University Press on behalf of Poultry Science Association.

  1. Multiplex Reverse Transcription-Polymerase Chain Reaction untuk Deteksi Cepat Virus Flu Burung H5N1 (MULTIPLEX REVERSE TRANSCRIPTION-POLYMERASE CHAIN REACTION FOR RAPID DETECTION OF H5N1 AVIAN INFLUENZA VIRUS

    Directory of Open Access Journals (Sweden)

    Raden Wasito

    2015-05-01

    Full Text Available Avian influenza virus subtype H5N1 (AIV H5N1 is highly pathogenic and fatal in poultry. The virusis still endemic with low virulence rate, although it may play a critical role in causing high morbidity andmortality rates in poultry in Indonesia. In general, diagnostic approach for AIV H5N1 is based onconventional serological and viral isolation methods that have the potential to produce consumings oftime and relatively expensive cost within the laboratory without compromising test utility. Thus, amolecular approach of multiplex reverse transcription-polymerase chain reaction (mRT-PCR was developedand applied for the detection of matrix gene type A influenza viruses, AIV subtype subtype H5hemagglutinin gene with simultaneous detection of N1 nucleoprotein gene. Thirty sera specimens fromthe diseased commercial chickens that were specifically amplified positive-RT-PCR for AIV H5N1 wereselected for mRT-PCR. The mRT-PCR products were visualized by agarose gel electrophoresis and consistedof DNA fragments of AIV of 245 bp, 545 bp and 343 bp for M, H5 and N1 genes, respectively. Thus, themRT-PCR that can rapidly differentiate simultaneously between these genes is very important for thecontrol and even eradication of AIV transmission in poultry in Indonesia.

  2. Study on Exothermic Oxidation of Acrylonitrile-butadiene-styrene (ABS Resin Powder with Application to ABS Processing Safety

    Directory of Open Access Journals (Sweden)

    Jenq-Renn Chen

    2010-08-01

    Full Text Available Oxidative degradation of commercial grade ABS (Acrylonitrile-butadiene-styrene resin powders was studied by thermal analysis. The instabilities of ABS containing different polybutadiene (PB contents with respect to temperature were studied by Differential Scanning Calorimeter (DSC. Thermograms of isothermal test and dynamic scanning were performed. Three exothermic peaks were observed and related to auto-oxidation, degradation and oxidative decomposition, respectively. Onset temperature of the auto-oxidation was determined to be around 193 °C. However, threshold temperature of oxidation was found to be as low as 140 °C by DSC isothermal testing. Another scan of the powder after degeneration in air showed an onset temperature of 127 °C. Reactive hazards of ABS powders were verified to be the exothermic oxidation of unsaturated PB domains, not the SAN (poly(styrene-acrylonitrile matrix. Heat of oxidation was first determined to be 2,800 ± 40 J per gram of ABS or 4,720 ± 20 J per gram of PB. Thermal hazards of processing ABS powder are assessed by adiabatic temperature rise at process conditions. IR spectroscopy associated with heat of oxidation verified the oxidative mechanism, and these evidences excluded the heat source from the degradation of SAN. A specially prepared powder of ABS without adding anti-oxidant was analyzed by DSC for comparing the exothermic behaviors. Exothermic onset temperatures were determined to be 120 °C and 80 °C by dynamic scanning and isothermal test, respectively. The assessment successfully explained fires and explosions in an ABS powder dryer and an ABS extruder.

  3. A rapid method for the detection of foodborne pathogens by extraction of a trace amount of DNA from raw milk based on label-free amino-modified silica-coated magnetic nanoparticles and polymerase chain reaction

    Science.gov (United States)

    A method based on amino-modified silica-coated magnetic nanoparticles (ASMNPs) and polymerase chain reaction (PCR) was developed to rapidly and sensitively detect foodborne pathogens in raw milk. After optimizing parameters such as pH, temperature, and time, a trace amount of genomic DNA of pathogen...

  4. Influence of the volumes of bis-acryl and poly(methyl methacrylate) resins on their exothermic behavior during polymerization.

    Science.gov (United States)

    Ha, Jung-Yun; Kim, Sung-Hun; Kim, Kyo-Han; Kwon, Tae-Yub

    2011-01-01

    This study aimed to evaluate the influence of the volumes of a bis-acryl resin (Luxatemp) and a poly(methyl methacrylate) resin (Jet) on their exothermic behaviors during polymerization based on vinyl group conversion. The number of vinyl groups reacted and exotherm were determined based on weight percent of methacrylate groups using FTIR spectroscopy. Temperature changes during polymerization at 23°C were recorded for 20 minutes using a multiple cavity mold overlying a thermocouple. The number of vinyl groups reacted and exotherm of Luxatemp were consistently lower than those of Jet at each resin volume. Mean peak temperature rises of Luxatemp and Jet were in the range of 2.0-6.6°C and 4.2-11.6°C respectively, with Luxatemp and Jet taking 2 and 10 minutes respectively to reach their peak temperatures. As their resin volumes increased, their peak temperatures and total peak areas were also observed to increase significantly (p<0.01).

  5. A Self-Propagating Foaming Process of Porous Al-Ni Intermetallics Assisted by Combustion Reactions

    Directory of Open Access Journals (Sweden)

    Makoto Kobashi

    2009-12-01

    Full Text Available The self-propagating foaming process of porous Al-Ni intermetallics was investigated. Aluminum and nickel powders were blended, and titanium and boron carbide powders were added as reactive exothermic agents. The blended powder was extruded to make a rod-shape precursor. Only one end of the rod precursor was heated to ignite the reaction. The reaction propagated spontaneously throughout the precursor. Pore formation took place at the same time as the reaction occurred. Adding the exothermic agent was effective to increase the porosity. Preheating the precursor before the ignition was also very effective to produce porous Al-Ni intermetallics with high porosity.

  6. A Reaction Coating on Aluminium Alloys by Laser Processing

    NARCIS (Netherlands)

    Zhou, X.B.; Hosson, J.Th.M. De

    1993-01-01

    An aluminium oxide layer of 100 µm in thickness has been successfully coated on aluminium alloy 6061 and pure aluminium using a powder mixture of silicon oxide and aluminium by laser processing. A strong Al/Al2O3 interface was formed. The exothermic chemical reaction between SiO2 and Al may promote

  7. The nature of the intermediates in the reactions of Fe(III)- and Mn(III)-microperoxidase-8 with H(2)O(2): a rapid kinetics study.

    Science.gov (United States)

    Primus, Jean-Louis; Grunenwald, Sylvie; Hagedoorn, Peter-Leon; Albrecht-Gary, Anne-Marie; Mandon, Dominique; Veeger, Cees

    2002-02-20

    Kinetic studies were performed with microperoxidase-8 (Fe(III)MP-8), the proteolytic breakdown product of horse heart cytochrome c containing an octapeptide linked to an iron protoporphyrin IX. Mn(III) was substituted for Fe(III) in Mn(III)MP-8. The mechanism of formation of the reactive metal-oxo and metal-hydroperoxo intermediates of M(III)MP-8 upon reaction of H(2)O(2) with Fe(III)MP-8 and Mn(III)MP-8 was investigated by rapid-scan stopped-flow spectroscopy and transient EPR. Two steps (k(obs1) and k(obs2)) were observed and analyzed for the reaction of hydrogen peroxide with both catalysts. The plots of k(obs1) as function of [H(2)O(2)] at pH 8.0 and pH 9.1 for Fe(III)MP-8, and at pH 10.2 and pH 10.9 for Mn(III)MP-8, exhibit saturation kinetics, which reveal the accumulation of an intermediate. Double reciprocal plots of 1/k(obs1) as function of 1/[H(2)O(2)] at different pH values reveal a competitive effect of protons in the oxidation of M(III)MP-8. This effect of protons is confirmed by the linear dependence of 1/k(obs1) on [H(+)] showing that k(obs1) increases with the pH. The UV-visible spectra of the intermediates formed at the end of the first step (k(obs1)) exhibit a spectrum characteristic of a high-valent metal-oxo intermediate for both catalysts. Transient EPR of Mn(III)MP-8 incubated with an excess of H(2)O(2), at pH 11.5, shows the detection of a free radical signal at g approximately equal to 2 and of a resonance at g approximately equal to 4 characteristic of a Mn(IV) (S = 3/2) species. On the basis of these results, the following mechanism is proposed: (i) M(III)MP-8-OH(2) is deprotonated to M(III)MP-8-OH in a rapid preequilibrium step, with a pK(a) = 9.2 +/- 0.9 for Fe(III)MP-8 and a pK(a) = 11.2 +/- 0.3 for Mn(III)MP-8; (ii) M(III)MP-8-OH reacts with H(2)O(2) to form Compound 0, M(III)MP8-OOH, with a second-order rate constant k(1) = (1.3 +/- 0.6) x 10(6) M(-1) x s(-1) for Fe(III)MP-8 and k(1) = (1.6 +/- 0.9) x 10(5) M(-1) x s(-1) for Mn

  8. Using real-time polymerase chain reaction as an alternative rapid method for enumeration of colony count in live Brucella vaccines

    Directory of Open Access Journals (Sweden)

    Waleed S. Shell

    2017-06-01

    Full Text Available Aim: Brucellosis is a major bacterial zoonosis of global importance affecting a range of animal species and man worldwide. It has economic, public health, and bio-risk importance. Control and prevention of animal brucellosis mainly depend on accurate diagnostic tools and implementation of effective and safe animal vaccination program. There are three types of animal Brucella live vaccines - Brucella melitensis Rev-1 vaccine, Brucella abortus S19, and B. abortus RB51. Evaluation of these vaccines depends mainly on enumeration of Brucella viable count. At present, used colony count method is time consuming, costly and requires especial skills. Hence, the aim of this study is to use and standardize real-time polymerase chain reaction (RT-PCR as an alternative, quantitative, sensitive, and rapid method to detect the colony count of Brucella in live Brucella vaccine. Materials and Methods: Four batches of different live Brucella vaccines were evaluated using of conventional bacterial count and RT-quantitative PCR (RT-qPCR using BSCP31 gene specific primers and probe. Standard curve was generated from DNA template extracted from 10-fold serial dilution of living B. abortus RB51 vaccine to evaluate the sensitivity of RT-qPCR. Results: Results revealed that three batches of living Brucella vaccines were acceptable for Brucella colony count when traditional bacterial enumeration method was used. Results of RT-qPCR were identical to that of conventional bacterial count. Conclusion: Results concluded that RT-qPCR was relatively sensitive compared to traditional bacterial colony count of these vaccines.

  9. Singular perturbation approach to flame theory with chain and competing reactions

    Energy Technology Data Exchange (ETDEWEB)

    Fife, P.C.; Nicolaenko, B.

    1982-01-01

    We investigate the structure of laminar flames with two chemical reactions in the limit of high activation energy asymptotics. Depending on the specific reaction network and the other given chemical data, a wide variety of flame configurations are possible. Here we fully explore these possibilities in the case of sequential and competing reaction pairs. Our methods are general enough to extend to most reaction networks with two or three exothermic reactions with high activation energy.

  10. Characteristics and mechanism of explosive reactions of Purex solvents with Nitric Acid at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Miyata, Teijiro [Radiation Application Development Association, Tokai, Ibaraki (Japan); Takada, Junichi; Koike, Tadao; Tsukamoto, Michio; Watanabe, Koji [Department of Fuel Cycle Safety Research, Nuclear Safety Research Center, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan); Ida, Masaaki [JGC PLANTECH CO., LTD (Japan); Nakagiri, Naotaka [JGC Corp., Tokyo (Japan); Nishio, Gunji [Research Organization for Information Science and Technology, Tokai, Ibaraki (Japan)

    2000-03-01

    This investigation was undertaken to make clear the energetic properties and mechanism of explosive decomposition of Purex solvent systems (TBP/n-Dodecane/HNO{sub 3}) by Nitric Acid at elevated temperatures using a calorimetric technique (DSC, ARC) and a chromatographic technique (GC, GC/MS). The measurement of exothermic events of solvent-HNO{sub 3} reactions using DSC with a stainless steel sealed cell showed distinct two peaks with maxima at around 170 and 320degC, respectively. The peak at around 170degC was mainly attributed to the reactions of dealkylation products (n-butyl nitrate) of TBP and the solvent with nitric acid, and the peak at around 320degC was attributed to the exothermic decomposition of nitrated dodecanes formed in the foregoing exothermic reaction of dodecane with nitric acid. By using the data obtained in ARC experiments, activation energies of 123.2 and 152.5 kJ/mol were determined for the exothermic reaction of TBP with nitric acid and for the exothermic pyrolysis of n-butyl nitrate, respectively. Some possible pathways were considered for the explosive decomposition of TBP by nitric acid at elevated temperatures. (author)

  11. Nuclear transit study in children with chronic faecal soiling after Hirschsprung disease (HSCR) surgery has revealed a group with rapid proximal colonic treatment and possible adverse reactions to food.

    Science.gov (United States)

    Stathopoulos, Lefteris; King, Sebastian K; Southwell, Bridget R; Hutson, John M

    2016-08-01

    Long-term problems with faecal incontinence occur in up to 50 % of patients after pull-through for Hirschsprung disease (HSCR). The cause often remains unknown, leading to empirical treatments. Using nuclear transit study, we found some patients surprisingly had rapid proximal colonic transit, suspicious of occult diarrhoea. We aimed to assess whether these patients had unrecognized adverse reactions to food. Patients (n = 10, all males, 9.6 year; 4.25-15.5 years) with persistent faecal incontinence following pull-through for HSCR referred to the senior author and after exclusion of anatomical defects, underwent nuclear transit studies. Most (8) subsequently underwent breath hydrogen tests for sugar malabsorption and were tested for adverse reactions to food. Exclusion diets for protein allergens, lactose or fructose were then trialed. Of the 10 patients with rapid intestinal transit proven on nuclear transit study, breath hydrogen tests for fructose and/or lactose malabsorption were done in 8, and were positive in 7/8 patients. Exclusion diets contributed to either resolution or improvement in faecal incontinence in 9/10 patients. Rapid transit in the proximal, ganglionated colon may be present in children with faecal incontinence following pull-through for HSCR, possibly secondary to adverse reactions to food. This study suggests that children with post-operative soiling may benefit from a transit study and hydrogen breath tests to diagnose adverse reactions to food caused by sugar malabsorption.

  12. Evaluation of a rapid analyte measurement platform and real-time reverse-transcriptase polymerase chain reaction assay West Nile virus detection system in mosquito pools.

    Science.gov (United States)

    Burkhalter, Kristen L; Horiuchi, Kalanthe; Biggerstaff, Brad J; Savage, Harry M; Nasci, Roger S

    2014-03-01

    We evaluated the commercially available Rapid Analyte Measurement Platform (RAMP) West Nile virus (WNV) antigen detection test for sensitivity and consistency with real-time reverse transcriptase polymerase chain reaction (RT-PCR) confirmation testing. Panels of samples consisting of WNV-spiked mosquito pools and negative control pools were sent to 20 mosquito abatement districts (MADs) that processed the pools using the RAMP assay. The samples were then sent to the reference laboratories used by the MADs for confirmation by real-time RT-PCR. Positive pools with virus titers of roughly 1-3 log10 PFU/ml had RAMP scores above the RAMP test positive cutoff score of 30 RAMP units, but these virus-positive samples could not be reliably confirmed by real-time RT-PCR testing. Pools with virus titers > or =4 log10 PFU/ml scored > or =50 RAMP units. Real-time RT-PCR results varied among the confirmation laboratories. With few exceptions, pools returning a RAMP score of > or =100 were confirmed with real-time RT-PCR, while pools returning a RAMP score of 50-99 appeared to be at the limit of real-time RT-PCR detection. Therefore, we recommend using a positive cutoff of 50 RAMP units with no real-time RT-PCR confirmation to maximize speed, efficiency, and economy of the RAMP assay. A more conservative approach would be to implement a "gray zone" range of 50-100 RAMP units. Pools scoring within the gray zone could be submitted for real-time RT-PCR confirmation with the understanding that positive pools may not confirm due to the inhibitory effect of the RAMP buffer on the real-time RT-PCR assay. We also conducted a series of experiments using laboratory-prepared mosquito pools spiked with WNV to compare mosquito homogenization buffers, pool sizes, and grinding methods in order to determine how these variables affect the RAMP and real-time RT-PCR assay results.

  13. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng [Irvine, CA; Sui, Guodong [Los Angeles, CA; Elizarov, Arkadij [Valley Village, CA; Kolb, Hartmuth C [Playa del Rey, CA; Huang, Jiang [San Jose, CA; Heath, James R [South Pasadena, CA; Phelps, Michael E [Los Angeles, CA; Quake, Stephen R [Stanford, CA; Tseng, Hsian-rong [Los Angeles, CA; Wyatt, Paul [Tipperary, IE; Daridon, Antoine [Mont-Sur-Rolle, CH

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  14. Influence of rovibrational excitation on the non-diabatic state-to-state dynamics for the Li(2p) + H2 → LiH + H reaction.

    Science.gov (United States)

    He, Di; Yuan, Jiuchuang; Chen, Maodu

    2017-06-08

    The non-adiabatic state-to-state dynamics of the Li(2p) + H2 → LiH + H reaction has been studied using the time-dependent wave packet method, based on a set of diabatic potential energy surfaces recently developed by our group. Integral cross sections (ICSs) can be increase more than an order of magnitude by the vibrational excitation of H2, whereas the ICSs are barely affected by the rotational excitation of H2. Moreover, ICSs of the title reaction with vibrationally excited H2 decrease rapidly with increasing collision energy, which is a typical feature of non-threshold reaction. This phenomenon implies that the title reaction can transformed from an endothermic to an exothermic reaction by vibrational excitation of H2. With the increase of the collision energy, the sideways and backward scattered tendencies of LiH for the Li(2p) + H2(v = 0, j = 0, 1) → LiH + H reactions are enhanced slightly, while the backward scattering tendency of LiH for the Li(2p) + H2(v = 1, j = 0) → LiH + H reaction becomes remarkably weakened. For the reaction with vibrationally excited H2 molecule, both direct and indirect reaction mechanism exist simultaneously.

  15. An enantioselective cascade reaction between α,β-unsaturated aldehydes and malonic half-thioesters: a rapid access to chiral δ-lactones.

    Science.gov (United States)

    Ren, Qiao; Sun, Shaofa; Huang, Jiayao; Li, Wenjun; Wu, Minghu; Guo, Haibing; Wang, Jian

    2014-06-11

    We disclose a novel efficient enantioselective organocatalytic cascade reaction for the preparation of δ-lactones in good to excellent yields (69-93%) and with high to excellent enantioselectivities (88-96% ee).

  16. A Study on the Physical Properties and Interfacial Reactions with Cu Substrate of Rapidly Solidified Sn-3.5Ag Lead-Free Solder

    Science.gov (United States)

    Ma, Hai-Tao; Wang, Jie; Qu, Lin; Zhao, Ning; Kunwar, A.

    2013-08-01

    A rapidly solidified Sn-3.5Ag eutectic alloy produced by the melt-spinning technique was used as a sample in this research to investigate the microstructure, thermal properties, solder wettability, and inhibitory effect of Ag3Sn on Cu6Sn5 intermetallic compound (IMC). In addition, an as-cast Sn-3.5Ag solder was prepared as a reference. Rapidly solidified and as-cast Sn-3.5Ag alloys of the same size were soldered at 250°C for 1 s to observe their instant melting characteristics and for 3 s with different cooling methods to study the inhibitory effect of Ag3Sn on Cu6Sn5 IMC. Experimental techniques such as scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectrometry were used to observe and analyze the results of the study. It was found that rapidly solidified Sn-3.5Ag solder has more uniform microstructure, better wettability, and higher melting rate as compared with the as-cast material; Ag3Sn nanoparticles that formed in the rapidly solidified Sn-3.5Ag solder inhibited the growth of Cu6Sn5 IMC during aging significantly much strongly than in the as-cast material because their number in the rapidly solidified Sn-3.5Ag solder was greater than in the as-cast material with the same soldering process before aging. Among the various alternative lead-free solders, this study focused on comparison between rapidly solidified and as-cast solder alloys, with the former being observed to have better properties.

  17. Kinetics of back reaction between radiolytic products initiated by radiation-induced voids in NaC1

    NARCIS (Netherlands)

    Turkin, AA; Dubinko, [No Value; Vainshtein, DI; den Hartog, HW

    2001-01-01

    A time-dependent model is formulated for the chemical reaction between sodium colloids and gas bubbles, which are brought into contact with each other by the growing voids. It is shown that in this exothermic reaction, heat is released much faster than it is dissipated by conduction to the

  18. Rapid detection of health-care-associated bloodstream infection in critical care using multipathogen real-time polymerase chain reaction technology: a diagnostic accuracy study and systematic review.

    Science.gov (United States)

    Warhurst, Geoffrey; Dunn, Graham; Chadwick, Paul; Blackwood, Bronagh; McAuley, Daniel; Perkins, Gavin D; McMullan, Ronan; Gates, Simon; Bentley, Andrew; Young, Duncan; Carlson, Gordon L; Dark, Paul

    2015-05-01

    There is growing interest in the potential utility of real-time polymerase chain reaction (PCR) in diagnosing bloodstream infection by detecting pathogen deoxyribonucleic acid (DNA) in blood samples within a few hours. SeptiFast (Roche Diagnostics GmBH, Mannheim, Germany) is a multipathogen probe-based system targeting ribosomal DNA sequences of bacteria and fungi. It detects and identifies the commonest pathogens causing bloodstream infection. As background to this study, we report a systematic review of Phase III diagnostic accuracy studies of SeptiFast, which reveals uncertainty about its likely clinical utility based on widespread evidence of deficiencies in study design and reporting with a high risk of bias. Determine the accuracy of SeptiFast real-time PCR for the detection of health-care-associated bloodstream infection, against standard microbiological culture. Prospective multicentre Phase III clinical diagnostic accuracy study using the standards for the reporting of diagnostic accuracy studies criteria. Critical care departments within NHS hospitals in the north-west of England. Adult patients requiring blood culture (BC) when developing new signs of systemic inflammation. SeptiFast real-time PCR results at species/genus level compared with microbiological culture in association with independent adjudication of infection. Metrics of diagnostic accuracy were derived including sensitivity, specificity, likelihood ratios and predictive values, with their 95% confidence intervals (CIs). Latent class analysis was used to explore the diagnostic performance of culture as a reference standard. Of 1006 new patient episodes of systemic inflammation in 853 patients, 922 (92%) met the inclusion criteria and provided sufficient information for analysis. Index test assay failure occurred on 69 (7%) occasions. Adult patients had been exposed to a median of 8 days (interquartile range 4-16 days) of hospital care, had high levels of organ support activities and recent

  19. An enzyme-activatable probe with a self-immolative linker for rapid and sensitive alkaline phosphatase detection and cell imaging through a cascade reaction.

    Science.gov (United States)

    Zhang, Hongmei; Xu, Chenglong; Liu, Jie; Li, Xiaohong; Guo, Lin; Li, Xinming

    2015-04-25

    We report the design and synthesis of a novel probe (1) for ALP assay by incorporating a self-immolative linker between a phosphate moiety and resorufin. Because of its good biocompatibility and rapid cell internalization, this probe also exhibited great potential for real-time monitoring of endogenous phosphatase activity in living cells.

  20. Rapid and sensitive detection of Mycoplasma synoviae by an insulated isothermal polymerase chain reaction-based assay on a field-deployable device

    OpenAIRE

    Kuo, Hung-Chih; Lo, Dan-Yuan; Chen, Chiou-Lin; Tsai, Yun-Long; Ping, Jia-Fong; Lee, Chien-Hsien; Lee, Pei-Yu Alison; Chang, Hsiao-Fen Grace

    2016-01-01

    Mycoplasma synoviae (MS), causing respiratory diseases, arthritis, and eggshell apex abnormalities in avian species, is an important pathogen in the poultry industry. Implementation of a biosecurity plan is important in MS infection management. Working on a field-deployable POCKIT? device, an insulated isothermal polymerase chain reaction (iiPCR) assay has a potential for timely MS detection on the farm. The MS iiPCR assay had limit of detection 95% of about 9 genome equivalents by testing se...

  1. A Preliminary Investigation of Rapid Depressurization Phenomena Following a Sudden DLOFC in a VHTR

    Energy Technology Data Exchange (ETDEWEB)

    Richard C. Martineau; Ray A. Berry; Dana A. Knoll

    2009-03-01

    Air ingress has been identified as a potential threat for Very High Temperature gas-cooled Reactors (VHTR). Reactor components constructed of graphite will, at high temperatures, produce exothermic reactions in the presence of oxygen. The danger lies in the possibility of fuel element damage and core structural failure. Previous investigations of air ingress mechanisms have focused on thermal and molecular diffusion, density-driven stratified flow, and natural convection. Here, we investigate the possibility of a rapid ingress of air due to a Taylor wave expansion after a hypothetical sudden loss of coolant accident (LOCA) scenario in a VHTR. Our analysis starts with a one-dimensional shock tube simulation to simply illustrate the development of a Taylor wave with resulting reentrant flow. Then, a simulation is performed of an idealized two-dimensional axisymmetric representation of the lower plenum of General Atomics GT-MHR subjected to a hypothetical catastrophic break of the hot duct. Analysis shows the potential for significant and rapid air ingress into the reactor vessel in the case of a large break in the cooling system.

  2. Perspective: Bimolecular chemical reaction dynamics in liquids.

    Science.gov (United States)

    Orr-Ewing, Andrew J

    2014-03-07

    Bimolecular reactions in the gas phase exhibit rich and varied dynamical behaviour, but whether a profound knowledge of the mechanisms of isolated reactive collisions can usefully inform our understanding of reactions in liquid solutions remains an open question. The fluctuating environment in a liquid may significantly alter the motions of the reacting particles and the flow of energy into the reaction products after a transition state has been crossed. Recent experimental and computational studies of exothermic reactions of CN radicals with organic molecules indicate that many features of the gas-phase dynamics are retained in solution. However, observed differences may also provide information on the ways in which a solvent modifies fundamental chemical mechanisms. This perspective examines progress in the use of time-resolved infra-red spectroscopy to study reaction dynamics in liquids, discusses how existing theories can guide the interpretation of experimental data, and suggests future challenges for this field of research.

  3. Rapid analysis of rearranged kappa light chain genes of circulating polysaccharide-specific B lymphocytes by means of immunomagnetic beads and the polymerase chain reaction

    DEFF Research Database (Denmark)

    Hougs, L; Barington, T; Madsen, HO

    1993-01-01

    -secreting cells. Examples of rearranged kappa genes used by HibCP-specific antibody-secreting cells from 4 adult vaccinees are given, representing the 3 largest of the 4 kappa variable region families. This method is a new tool for the investigation of vaccine-induced antibody responses with special reference...... of the B lymphocytes activated in vivo. Here, we present a method for rapid analysis of the rearranged kappa light chain genes used by human circulating antigen-specific B lymphocytes. After vaccination with Haemophilus influenzae type b capsular polysaccharide (HibCP) conjugated with protein, the Hib...

  4. Rapid differentiation and identification of potential severe strains of Citrus tristeza virus by real-time reverse transcription-polymerase chain reaction assays.

    Science.gov (United States)

    Yokomi, R K; Saponari, M; Sieburth, P J

    2010-04-01

    A multiplex Taqman-based real-time reverse transcription (RT) polymerase chain reaction (PCR) assay was developed to identify potential severe strains of Citrus tristeza virus (CTV) and separate genotypes that react with the monoclonal antibody MCA13. Three strain-specific probes were developed using intergene sequences between the major and minor coat protein genes (CPi) in a multiplex reaction. Probe CPi-VT3 was designed for VT and T3 genotypes; probe CPi-T36 for T36 genotypes; and probe CPi-T36-NS to identify isolates in an outgroup clade of T36-like genotypes mild in California. Total nucleic acids extracted by chromatography on silica particles, sodium dodecyl sulfate-potassium acetate, and CTV virion immunocapture all yielded high quality templates for real-time PCR detection of CTV. These assays successfully differentiated CTV isolates from California, Florida, and a large panel of CTV isolates from an international collection maintained in Beltsville, MD. The utility of the assay was validated using field isolates collected in California and Florida.

  5. Antibiotic susceptibility testing of grown blood cultures by combining culture and real-time polymerase chain reaction is rapid and effective.

    Directory of Open Access Journals (Sweden)

    Judith Beuving

    Full Text Available BACKGROUND: Early administration of appropriate antibiotic therapy in bacteraemia patients dramatically reduces mortality. A new method for RApid Molecular Antibiotic Susceptibility Testing (RAMAST that can be applied directly to positive blood cultures was developed and evaluated. METHODOLOGY/PRINCIPAL FINDINGS: Growth curves and antibiotic susceptibility of blood culture isolates (Staphylococcus aureus, enterococci and (facultative aerobic gram-negative rods were determined by incubating diluted blood cultures with and without antibiotics, followed by a quantitative universal 16S PCR to detect the presence or absence of growth. Testing 114 positive blood cultures, RAMAST showed an agreement with microbroth dilution of 96.7% for gram-negative rods, with a minor error (false-susceptibility with a intermediate resistant strain rate of 1.9%, a major error (false resistance rate of 0.8% and a very major error (false susceptibility rate of 0.6%. Agreement for S. aureus was 97.9%, with a very major error rate of 2.1%. Enterococcus species showed 95.0% agreement, with a major error rate of 5.0%. These agreements are comparable with those of the Phoenix system. Starting from a positive blood culture, the test was completed within 9 hours. CONCLUSIONS/SIGNIFICANCE: This new rapid method for antibiotic susceptibility testing can potentially provide accurate results for most relevant bacteria commonly isolated from positive blood cultures in less time than routine methods.

  6. Visualization of enzyme-catalyzed reactions using pH indicators: rapid screening of hydrolase libraries and estimation of the enantioselectivity.

    Science.gov (United States)

    Morís-Varas, F; Shah, A; Aikens, J; Nadkarni, N P; Rozzell, J D; Demirjian, D C

    1999-10-01

    The use of pH indicators to monitor hydrolase-catalyzed reactions is described. The formation of acid following an enzyme-mediated hydrolysis causes a drop in the pH that can be visualized by a change in the color of the indicator-containing solution. The best indicators are those showing a color transition within the operational pH range of the hydrolases, like bromothymol blue and phenol red. The enantioselectivity of lipases and esterases can be estimated using single isomers under the same conditions and comparing the color turnover for each one. The method has been tested to quickly evaluate the enantioselectivity of a lipase towards a set of ester substrates and applied to the hierarchical screening of a library of thermophilic esterases.

  7. Rapid, high-throughput detection of azalea lace bug (Hemiptera: Tingidae) predation by Chrysoperla rufilabris (Neuroptera: Chrysopidae), using fluorescent-polymerase chain reaction primers.

    Science.gov (United States)

    Rinehart, Timothy A; Boyd, David W

    2006-12-01

    Azalea lace bugs, Stephanitis pyrioides (Scott) (Hemiptera: Tingidae), are the most common pest of azaleas (Rhododendron spp.) in nursery production and the landscape. Although pesticides are commonly used to control lace bugs, natural enemies can be a significant source of lace bug mortality. Lacewings (Neuroptera: Chrysopidae) are natural enemies of lace bugs and easily consume them in laboratory studies. Field studies on lacewing biocontrol of azalea lace bugs are underway; however, monitoring lacewing predation in a nursery environment by direct observation is impractical. Here, we describe a fluorescent-polymerase chain reaction method to estimate S. pyrioides consumption based on the gut contents of lacewing predators. Lace bug DNA was detected in fed lacewings up to 32 h after ingestion. More than 80% of the ingested lace bugs were detected using our method with only one false positive result. The assay is both high-throughput and relatively inexpensive, making it a practical approach to documenting lace bug predation in the field.

  8. A Rapid One-Pot Synthesis of Novel High-Purity Methacrylic Phosphonic Acid (PA-Based Polyhedral Oligomeric Silsesquioxane (POSS Frameworks via Thiol-Ene Click Reaction

    Directory of Open Access Journals (Sweden)

    K. Karuppasamy

    2017-05-01

    Full Text Available Herein, we demonstrate a facile methodology to synthesis a novel methacrylic phosphonic acid (PA-functionalized polyhedral oligomeric silsesquioxanes (POSSs via thiol-ene click reaction using octamercapto thiol-POSS and ethylene glycol methacrylate phosphate (EGMP monomer. The presence of phosphonic acid moieties and POSS-cage structure in POSS-S-PA was confirmed by Fourier transform infrared (FT-IR and nuclear magnetic resonance (1H, 29Si and 31P-NMR analyses. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF mass spectrum of POSS-S-PA acquired in a dithranol matrix, which has specifically designed for intractable polymeric materials. The observed characterization results signposted that novel organo-inorganic hybrid POSS-S-PA would be an efficacious material for fuel cells as a proton exchange membrane and high-temperature applications due to its thermal stability of 380 °C.

  9. A rapid method for the detection of representative coliforms in water samples: polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA).

    Science.gov (United States)

    Kuo, Jong-Tar; Cheng, Chiu-Yu; Huang, Hsiao-Han; Tsao, Chia-Fen; Chung, Ying-Chien

    2010-03-01

    Methods to detect the presence of coliform bacteria in drinking water usually involve a series of complex cultivating steps that are time-consuming and subject to external influences. For this reason, the new 16S rRNA probe has been developed in this study as an alternative detector PCR-ELISA technique that does not involve the culture of bacteria and that is able to detect, identify, and quantify the representative coliform species present in water samples. Our results indicate that this technique is both rapid (detection time of 4 h) and accurate (1.4% error rate). The limit of detection (LOD) was 5 CFU/100 ml for total coliforms, which meets the standards set by most countries for drinking water. Our comparative study demonstrated that this PCR-ELISA method is superior to current conventional methods in terms of detection time, LOD, and accuracy.

  10. Fluorination of an Alumina Surface: Modeling Aluminum-Fluorine Reaction Mechanisms.

    Science.gov (United States)

    Padhye, Richa; Aquino, Adelia J A; Tunega, Daniel; Pantoya, Michelle L

    2017-07-19

    Density functional theory (DFT) calculations were performed to examine exothermic surface chemistry between alumina and four fluorinated, fragmented molecules representing species from decomposing fluoropolymers: F(-), HF, CH3F, and CF4. The analysis has strong implications for the reactivity of aluminum (Al) particles passivated by an alumina shell. It was hypothesized that the alumina surface structure could be transformed due to hydrogen bonding effects from the environment that promote surface reactions with fluorinated species. In this study, the alumina surface was analyzed using model clusters as isolated systems embedded in a polar environment (i.e., acetone). The conductor-like screening model (COSMO) was used to mimic environmental effects on the alumina surface. Four defect models for specific active -OH sites were investigated including two terminal hydroxyl groups and two hydroxyl bridge groups. Reactions involving terminal bonds produce more energy than bridge bonds. Also, surface exothermic reactions between terminal -OH bonds and fluorinated species produce energy in decreasing order with the following reactant species: CF4 > HF > CH3F. Additionally, experiments were performed on aluminum powders using thermal equilibrium analysis techniques that complement the calculations. Consistently, the experimental results show a linear relationship between surface exothermic reactions and the main fluorination reaction for Al powders. These results connect molecular level reaction kinetics to macroscopic measurements of surface energy and show that optimizing energy available in surface reactions linearly correlates to maximizing energy in the main reaction.

  11. Runaway behavior and thermally safe operation of multiple liquid-liquid reactions in the semi-batch reactor. The nitric acid oxidation of 2-octanol.

    NARCIS (Netherlands)

    van Woezik, B.A.A.; Westerterp, K.R.

    2001-01-01

    The thermal runaway behavior of an exothermic, heterogeneous, multiple reaction system has been studied in a cooled semi-batch reactor. The nitric acid oxidation of 2-octanol has been used to this end. During this reaction, 2-octanone is formed, which can be further oxidized to unwanted carboxylic

  12. An immunomagnetic separation-reverse transcription polymerase chain reaction (IMS-RT-PCR) test for sensitive and rapid detection of viable waterborne Cryptosporidium parvum.

    Science.gov (United States)

    Hallier-Soulier, Sylvie; Guillot, Emmanuelle

    2003-07-01

    The public health problem posed by the waterborne parasite Cryptosporidium parvum incited the water supply industry to develop very accurate analytical tools able to assess the presence of viable oocysts in drinking water. In this study, we report the development of a viability assay for C. parvum oocysts based on immunomagnetic separation and reverse transcription polymerase chain reaction (IMS-RT-PCR). The detection limit of the IMS-RT-PCR assay, which targets the hsp70 heat shock-induced mRNA, was in the range of ten viable oocysts per 100-l tap water samples. Purified Cryptosporidium parvum oocysts were exposed to heating, freezing and three chemical disinfection treatments namely, chlorination, chlorine dioxide treatment and ozonation under conventional doses used in water treatment plants, then detected by IMS-PCR and IMS-RT-PCR. The results obtained by IMS-PCR showed that none of the treatments had an effect on oocyst detection. The inactivation of oocysts by boiling resulted in no RT-PCR signal. Chlorine as well as chlorine dioxide did not influence oocyst viability as determined by IMS-RT-PCR. Ozone more effectively inactivated oocysts. The IMS-RT-PCR assay in conjunction with IMS-PCR marks the development of a combined detection and viability test which can be used for drinking water quality control as well as for reliable evaluation of treatment efficiency.

  13. A multiplex polymerase chain reaction based method for rapid identification of two species of the genus Scolytus Geoffroy (Col: Curculionidae: Scolytinae in Iran

    Directory of Open Access Journals (Sweden)

    S. Amini

    2016-04-01

    Full Text Available Molecular identification is going to be more widespread in taxonomic studies of insects when traditional tools are problematic and time consuming. Identification of bark beetles, as one of the most important pests of forests, based on morphological characteristics is difficult because of their small size and morphological similarities. In the current study, species-specific primers were desi gned to identify two most abundant and morphologically similar bark beetle species Scolytus ensifer Eichhoff 1881 and S. ecksteini Butovitsch 1929, both found on Ulmus minor Miller in north of Iran. These species-specific primers successfully produced a fragment size with 318 bp and 465 bp of mitochondrial cytochrome oxidase 1 (CO1 gene in S. ensifer and S. ecksteini respectively. The results revealed tha t the multiplex polymerase chain reaction using the species-specific primers could amplify a unique band to distinguish these two species so confirmed this method as a convenient and quick tool to identify those two bark beetle species.

  14. Rapid method for simultaneous determination of nitrite and nitrate in water samples using short-column ion-pair chromatographic separation, photochemical reaction, and chemiluminescence detection.

    Science.gov (United States)

    Kodamatani, Hitoshi; Yamazaki, Shigeo; Saito, Keiitsu; Komatsu, Yu; Tomiyasu, Takashi

    2011-01-01

    A rapid method has been developed for the simultaneous determination of nitrite and nitrate. The separation of nitrite and nitrate was achieved using an octadecylsilane (ODS) short column (5 µm, 20 × 4.6 mm) with 10 mM of borate buffer-methanol (99.5:0.5, v/v; pH 10.0), containing 5 mM of lauryltrimethylammonium chloride and 50 mM of NaBr. These ions were detected by luminol chemiluminescence following online UV irradiation. The calibration curves of nitrite and nitrate were linear in the range of 1.0 × 10(-7) to 2.0 × 10(-5) M and 1.0 × 10(-6) to 2.0 × 10(-4) M, respectively. The detection limits for nitrite and nitrate were 0.05 and 0.4 µM, respectively (with a signal-to-noise ratio of 3). The precisions of peak heights for 7 identical injections of a standard mixture of 0.50 µM of nitrite and 5.0 µM of nitrate were 2.7 and 2.1%, respectively. Analysis time per sample was less than 2 min, and system pressure was low (2.1 MPa). The proposed method was successfully applied to water samples from various sources.

  15. Rapid and sensitive on-line monitoring 6 different kinds of volatile organic compounds in aqueous samples by spray inlet proton transfer reaction mass spectrometry (SI-PTR-MS).

    Science.gov (United States)

    Zou, Xue; Kang, Meng; Wang, Hongmei; Huang, Chaoqun; Shen, Chengyin; Chu, Yannan

    2017-06-01

    Rapid and sensitive monitoring of volatile organic compounds (VOCs) in aqueous samples is very important to human health and environmental protection. In this study, an on-line spray inlet proton transfer reaction mass spectrometry (SI-PTR-MS) method was developed for the rapid and sensitive monitoring of 6 different kinds of VOCs, namely acetonitrile, acetaldehyde, ethanol, acetone, aether, and methylbenzene, in aqueous samples. The response time, limit of detection (LOD), and repeatability of the SI-PTR-MS system were evaluated. The response of the SI-PTR-MS was quite rapid with response times of 31-88 s. The LODs for all these VOCs were below 10 μg/L. The LOD of methylbenzene was 0.9 μg/L, much lower than the maximum contaminant level (MCL) in drinking water. The repeatability of this method was evaluated with 5 replicate determinations. The relative standard deviations (RSDs) were in the range of 0.8-3.1%, indicating good repeatability. To evaluate the matrix effects, the SI-PTR-MS system was employed for on-line monitoring of these 6 VOCs in different aqueous matrices, including lake water, tap water, and waste water. The relative recoveries were in the range of 94.6-106.0% for the lake water, 96.3-105.6% for the tap water, and 95.6-102.9% for the waste water. The results indicate that the SI-PTR-MS method has important application values in the rapid and sensitive monitoring of VOCs in these aqueous samples. In addition, the effect of salt concentration on the extracting efficiency was evaluated. The results showed that the LOD of the SI-PTR-MS could be further decreased by changing the salt concentration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Rapid Detection of Bloodstream Pathogens in Liver Transplantation Patients With FilmArray Multiplex Polymerase Chain Reaction Assays: Comparison With Conventional Methods.

    Science.gov (United States)

    Otlu, B; Bayindir, Y; Ozdemir, F; Ince, V; Cuglan, S; Hopoglu, M; Yakupogullari, Y; Kizilkaya, C; Kuzucu, C; Isık, B; Yilmaz, S

    2015-01-01

    Bloodstream infection (BSI) is an important concern in transplant patients. Early intervention with appropriate antimicrobial therapy is critical to better clinical outcome; however, there is significant delay when conventional identification methods are used. We aimed to determine the diagnostic performance of the FilmArray Blood Culture Identification Panel, a recently approved multiplex polymerase chain reaction assay detecting 24 BSI pathogens and 3 resistance genes, in comparison with the performances of conventional identification methods in liver transplant (LT) patients. A total of 52 defined sepsis episodes (signal-positive by blood culture systems) from 45 LT patients were prospectively studied. The FilmArray successfully identified 37 of 39 (94.8%) bacterial and 3 of 3 (100%) yeast pathogens in a total of 42 samples with microbial growth, failing to detect only 2 of 39 (5.1%) bacterial pathogens that were not covered by the test panel. The FilmArray could also detect additional pathogens in 3 samples that had been reported as having monomicrobial growth, and it could detect Acinetobacter baumannii in 2 samples suspected of skin flora contamination. The remaining 8 blood cultures showing a positive signal but yielding no growth were also negative by this assay. Results of MecA, KPC, and VanA/B gene detection were in high accordance. The FilmArray produced results with significantly shorter turnaround times (1.33 versus 36.2, 23.6, and 19.5 h; P FilmArray appeared as a reliable alternative diagnostic method with the potential to mitigate problems with protracted diagnosis of the BSI pathogens in LT patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Endonuclease Restriction-Mediated Real-Time Polymerase Chain Reaction: A Novel Technique for Rapid, Sensitive and Quantitative Detection of Nucleic-Acid Sequence

    Science.gov (United States)

    Wang, Yi; Wang, Yan; Zhang, Lu; Li, Machao; Luo, Lijuan; Liu, Dongxin; Li, Hua; Cao, Xiaolong; Hu, Shoukui; Jin, Dong; Xu, Jianguo; Ye, Changyun

    2016-01-01

    The article reported a novel methodology for real-time PCR analysis of nucleic acids, termed endonuclease restriction-mediated real-time polymerase chain reaction (ET-PCR). Just like PCR, ET-PCR only required one pair of primers. A short sequence, which was recognized by restriction enzyme BstUI, was attached to the 5′ end of the forward (F) or reverse (R) PCR primer, and the new F or R primer was named EF or ER. EF/ER was labeled at the 5′ end with a reporter dye and in the middle with a quenching dye. BstUI cleaves the newly synthesized double-stranded terminal sequences (5′ end recognition sequences and their complementary sequences) during the extension phase, which separates the reporter molecule from the quenching dye, leading to a gain of fluorescence signal. This process is repeated in each amplification cycle and unaffected the exponential synthesis of the PCR amplification. ET-PCR allowed real-time analysis of single or multiple targets in a single vessel, and provided the reproducible quantitation of nucleic acids. The analytical sensitivity and specificity of ET-PCR were successfully evaluated, detecting down to 250 fg of genomic DNA per tube of target pathogen DNA examined, and the positive results were generated in a relatively short period. Moreover, the practical application of ET-PCR for simultaneous detection of multiple target pathogens was also demonstrated in artificially contaminated blood samples. In conclusion, due to the technique’s simplicity of design, reproducible data and low contamination risk, ET-PCR assay is an appealing alternative to conventional approaches currently used for real-time nucleic acid analysis. PMID:27468284

  18. Energetics and control of ultracold isotope-exchange reactions between heteronuclear dimers in external fields

    Science.gov (United States)

    Tomza, Michal

    2017-04-01

    We show that isotope-exchange reactions between ground-state alkali-metal, alkaline-earth-metal, and lanthanide heteronuclear dimers consisting of two isotopes of the same atom are exothermic with an energy change in the range of 1-8000 MHz, thus resulting in cold or ultracold products. For these chemical reactions, there are only one rovibrational and at most several hyperfine possible product states. The number and energetics of open and closed reactive channels can be controlled by the laser and magnetic fields. We suggest a laser-induced isotope- and state-selective Stark shift control to tune the exothermic isotope-exchange reactions to become endothermic, thus providing the ground for testing models of the chemical reactivity. The present proposal opens the way for studying the state-to-state dynamics of ultracold chemical reactions beyond the universal limit with a meaningful control over the quantum states of both reactants and products.

  19. Rapid and facile preparation of zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide by microwave-solvothermal technique and its catalytic activity in heterogeneous photo-Fenton reaction

    Energy Technology Data Exchange (ETDEWEB)

    Anchieta, Chayene G.; Severo, Eric C.; Rigo, Caroline; Mazutti, Marcio A. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Kuhn, Raquel C., E-mail: raquelckuhn@yahoo.com.br [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Muller, Edson I.; Flores, Erico M.M. [Department of Chemistry, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil); Moreira, Regina F.P.M. [Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, 88040-970, Florianópolis (Brazil); Foletto, Edson L. [Department of Chemical Engineering, Federal University of Santa Maria, 97105-900, Santa Maria (Brazil)

    2015-06-15

    In this work zinc ferrite (ZnFe{sub 2}O{sub 4}) oxide was rapidly and easily prepared by microwave-solvothermal route and its catalytic property in photo-Fenton reaction was evaluated. The effects of microwave heating time and power on the properties of produced particles were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and nitrogen adsorption–desorption isotherms were the techniques used for characterizing the solid products. The synthesized material was tested as a catalyst in the degradation of the textile dye molecule by the heterogeneous photo-Fenton process. Characterization results showed that the microwave heating time and power have significant influences on the formation of the phase spinel as well as on its physical properties. The reaction results showed that the ZnFe{sub 2}O{sub 4} oxide has good photocatalytic activity, which can be attributed to high surface area and pore volume, and large pore size. The ZnFe{sub 2}O{sub 4} oxide produced by the microwave irradiation exhibited promising photocatalytic activity for the removal of textile dye, reaching nearly 100% of decolorization at 40 min and 60% of mineralization at 240 min. Therefore, ZnFe{sub 2}O{sub 4} particles rapidly prepared by the microwave route have the potential for use in treatment of textile wastewater by the heterogeneous photo-Fenton process. - Highlights: • ZnFe{sub 2}O{sub 4} was synthesized by microwave-solvothermal method. • ZnFe{sub 2}O{sub 4} was prepared by different microwave heating times and powers. • ZnFe{sub 2}O{sub 4} was used as heterogeneous photo-Fenton catalyst. • Degradation of Procion red dye using heterogeneous photo-Fenton process. • ZnFe{sub 2}O{sub 4} was highly efficient to degrade textile dye under visible light.

  20. DTA Studies on the Thermal Oxidation and Crosslinking Reactions of Carboxyl-Terminated Polybutadiene

    OpenAIRE

    Kishore, K; Verneker, Pai VR; Dharumaraj, Varghese G

    1984-01-01

    Studies on the thermal oxidation of carboxyl-terminated polybutadiene in the presence of antioxidants have been carried out by dynamic DTA. Bis-thioacetylacetonato nickel(II) compounds are found to be effective in inhibiting the air oxidation reaction in the polymer. The crosslinking reaction of the polymer through the double bonds present in the polymer molecule is desensitized by the antioxidants and the effect is more with N-phenyl-1-naphthylamine. An exothermic peak formed at $270^ \\circ ...

  1. A rapid and reliable species-specific identification of clinical and environmental isolates of Vibrio cholerae using a three-test procedure and recA polymerase chain reaction

    Directory of Open Access Journals (Sweden)

    A D Roozbehani

    2012-01-01

    Full Text Available Purpose: Vibrio cholerae, the cause of cholera, is one of the leading causes of morbidity and mortality in many developing countries. Most laboratories initially rely on biochemical tests for a presumptive identification of these strains, followed by a polymerase chain reaction (PCR-based method to confirm their identification. The aim of this study is to establish a rapid and reliable identification scheme for V. cholerae using a minimal, but highly specific number of biochemical tests and a PCR assay. Materials and Methods: We developed a species-specific PCR to identify V. cholerae, using a housekeeping gene recA, and used that to evaluate the sensitivity and specificity of 12 biochemical tests commonly used for screening and / or presumptive identification of V. cholerae in the clinical and environmental samples. Results: Here we introduced a combination of three biochemical tests, namely, sucrose fermentation, oxidase test, and growth in trypton broth containing 0% NaCl, as also the PCR of the recA gene, for rapid identification of V. cholerae isolates, with 100% sensitivity and specificity. The established method accurately identified a collection of 47 V. cholerae strains isolated from the clinical cases (n = 26 and surface waters (n = 21, while none of the 32 control strains belonging to different species were positive in this assay. Conclusion: The triple-test procedure introduced here is a simple and useful assay which can be adopted in cholera surveillance programs for efficient monitoring of V. cholerae in surface water and fecal samples.

  2. Rapid Biological Synthesis of Silver Nanoparticles from Ocimum sanctum and Their Characterization

    Directory of Open Access Journals (Sweden)

    M. Z. H. Khan

    2017-01-01

    Full Text Available With development of nanotechnology, the biological synthesis process deals with the synthesis, characterization, and manipulation of materials and further development at nanoscale which is the most cost-effective and eco-friendly and rapid synthesis process as compared to physical and chemical process. In this research silver nanoparticles (AgNPs were synthesized from silver nitrate (AgNO3 aqueous solution through eco-friendly plant leaf broth of Ocimum sanctum as reactant as well as capping agent and stabilizer. The formation of AgNPs was monitored by ultraviolet-visible spectrometer (UV-vis and Fourier transform infrared (FTIR spectroscopy. X-ray diffraction (XRD and scanning electronic microscopy (SEM have been used to characterize the morphology of prepared AgNPs. The peaks in XRD pattern are in good agreement with that of face-centered-cubic (FCC form of metallic silver. Thermal gravimetric analysis/differential thermal analysis (TGA/DTA results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The average grain size of silver nanoparticles is found to be 29 nm. The FTIR results indicated that the leaf broths containing the carboxyl, hydroxyl, and amine groups are mainly involved in fabrication of silver AgNPs and proteins, which have amine groups responsible for stabilizing AgNPs in the solution.

  3. Calculation of reaction energies and adiabatic temperatures for waste tank reactions

    Energy Technology Data Exchange (ETDEWEB)

    Burger, L.L.

    1995-10-01

    Continual concern has been expressed over potentially hazardous exothermic reactions that might occur in Hanford Site underground waste storage tanks. These tanks contain many different oxidizable compounds covering a wide range of concentrations. The chemical hazards are a function of several interrelated factors, including the amount of energy (heat) produced, how fast it is produced, and the thermal absorption and heat transfer properties of the system. The reaction path(s) will determine the amount of energy produced and kinetics will determine the rate that it is produced. The tanks also contain many inorganic compounds inert to oxidation. These compounds act as diluents and can inhibit exothermic reactions because of their heat capacity and thus, in contrast to the oxidizable compounds, provide mitigation of hazardous reactions. In this report the energy that may be released when various organic and inorganic compounds react is computed as a function of the reaction-mix composition and the temperature. The enthalpy, or integrated heat capacity, of these compounds and various reaction products is presented as a function of temperature; the enthalpy of a given mixture can then be equated to the energy release from various reactions to predict the maximum temperature which may be reached. This is estimated for several different compositions. Alternatively, the amounts of various diluents required to prevent the temperature from reaching a critical value can be estimated. Reactions taking different paths, forming different products such as N{sub 2}O in place of N{sub 2} are also considered, as are reactions where an excess of caustic is present. Oxidants other than nitrate and nitrite are considered briefly.

  4. A model for primary and heterogeneuos secondary reactions of wood pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Ahuja, P. [Dept. of Chemical Engineering and Technology, Inst. of Technology, Banaras Hindu Univ., Varanasi (India); Kumar, S. [Dept. of Chemical Engineering and Technology, Inst. of Technology, Banaras Hindu Univ., Varanasi (India); Singh, P.C. [Dept. of Chemical Engineering and Technology, Inst. of Technology, Banaras Hindu Univ., Varanasi (India)

    1996-06-01

    A chain growth model for heterogeneous secondary reactions is developed for the pyrolysis of large wood particles and the parameters determined by nonlinear optimization. The model takes both the volatile retention time and cracking and repolymerization reactions of the vapours with the decomposing solid as well as autocatalysis into consideration. The extent of the secondary reactions is strongly influenced by the time and the ratio of the autocatalytic (propagation) reaction rate to noncatalytic (initiation) reaction rate. The wood which has a higher value of the autocatalytic/noncatalytic ratio also has a higher exothermic heat of reaction and yields a higher amount of final char residue. This fact confirms that the heterogeneous secondary reactions lead to carbon enrichment of the final residue and are accompanied with an exothermic heat of reaction. The lower activation energies of the initiation and propagation reactions as compared to primary reactions (competitive reaction model consisting of weight loss and char forming reactions) confirm autocatalysis in large particles. The sealed reactor studies of small quantities of fine wood samples show that heterogeneous secondary reactions and not lower heating rates in large particles are the main source of char formed during the thermal decomposition of large wood particles. The model predictions are in agreement with the weight loss and temperature versus time curves over a wide range of particle size and furnace temperatures. (orig.)

  5. Dynamics of anion-molecule reactions at low energy

    Energy Technology Data Exchange (ETDEWEB)

    Mikosch, J.

    2007-11-15

    Anion-molecule reactions must find their way through deeply bound entrance and exit channel complexes separated by a central barrier. This results in low reaction rates and rich dynamics since direct pathways compete with the formation of transient intermediates. In this thesis we examine the probability of proton transfer to a small anion and transient lifetimes of a thermoneutral bimolecular nucleophilic substitution (S{sub N}2) reaction at well defined variable temperature down to 8 Kelvin in a multipole trap. The observed strong inverse temperature dependence is attributed to the deficit of available quantum states in the entrance channel at decreasing temperature. Furthermore we investigate scattering dynamics of S{sub N}2 reactions at defined relative energy between 0.4 and 10 eV by crossed beam slice imaging. A weakly exothermic reaction with high central barrier proceeds via an indirect, complex-mediated mechanism at low relative energies featuring high internal product excitation in excellent quantitative agreement with a statistical model. In contrast, direct backward scattering prevails for higher energies with product velocities close to the kinematical cutoff. For a strongly exothermic reaction, competing S{sub N}2-, dihalide- and proton transfer-channels are explored which proceed by complex mediation for low energy and various rebound-, grazing- and collision induced bond rupture-mechanisms at higher energy. From our data and a collaboration with theory we identify a new indirect roundabout S{sub N}2 mechanism involving CH{sub 3}-rotation. (orig.)

  6. Isotope exchange reactions involving HCO+ with CO: A theoretical approach

    Science.gov (United States)

    Mladenović, M.; Roueff, E.

    2017-09-01

    Aims: We aim to investigate fractionation reactions involved in the 12C/13C, 16O/18O, and 17O balance. Methods: Full-dimensional rovibrational calculations were used to compute numerically exact rovibrational energies and thermal equilibrium conditions to derive the reaction rate coefficients. A nonlinear least-squares method was employed to represent the rate coefficients by analytic functions. Results: New exothermicities are derived for 30 isotopic exchange reactions of HCO+ with CO. For each of the reactions, we provide the analytic three-parameter Arrhenius-Kooij formula for both the forward reaction and backward reaction rate coefficients, that can further be used in astrochemical kinetic models. Rotational constants derived here for the 17O containing forms of HCO+ may assist detection of these cations in outer space.

  7. Highly Sensitive Raman Spectroscopy with Low Laser Power for Fast In-Line Reaction and Multiphase Flow Monitoring.

    Science.gov (United States)

    Braun, Frank; Schwolow, Sebastian; Seltenreich, Julia; Kockmann, Norbert; Röder, Thorsten; Gretz, Norbert; Rädle, Matthias

    2016-10-04

    In process analytics, the applicability of Raman spectroscopy is restricted by high excitation intensities or the long integration times required. In this work, a novel Raman system was developed to minimize photon flux losses. It allows specific reduction of spectral resolution to enable the use of Raman spectroscopy for real-time analytics when strongly increased sensitivity is required. The performance potential of the optical setup was demonstrated in two exemplary applications: First, a fast exothermic reaction (Michael addition) was monitored with backscattering fiber optics under strongly attenuated laser power (7 mW). Second, high-speed scanning of a segmented multiphase flow (water/toluene) with submicroliter droplets was achieved by aligning the focus of a coaxial Raman probe with long focal length directly into a perfluoroalkoxy (PFA) capillary. With an acquisition rate of 333 Raman spectra per second, chemical information was obtained separately for both of the rapidly alternating phases. The experiment with reduced laser power demonstrates that the technique described in this paper is applicable in chemical production processes, especially in hazardous environments. Further potential uses can be envisioned in medical or biological applications with limited power input. The realization of high-speed measurements shows new possibilities for analysis of heterogeneous phase systems and of fast reactions or processes.

  8. Kinetics of the O + ICN reaction.

    Science.gov (United States)

    Feng, Wenhui; Hershberger, John F

    2012-05-24

    The kinetics of the O + ICN reaction was studied using a relative rate method, with O + C(2)H(2) as the competing reaction. Carbon monoxide products formed in the competing reaction and subsequent secondary chemistry were detected as a function of reagent ICN pressure to obtain total rate constants for the O + ICN reaction. Analysis of the experimental data yields rate constants of k(1) = (3.7 ± 1.0 to 26.2 ± 4.0) × 10(-14) cm(3) molecule(-1) s(-1) over the total pressure range 1.5-9.5 Torr. Product channel NCO + I, the only bimolecular exothermic channel of the reaction, was investigated by detection of N(2)O in the presence of NO and found to be insignificant. An ab initio calculation of the potential energy surface (PES) of the reaction at the CCSD(T)/CEP-31G//DFT-B3LYP/CEP-31G level of theory was also performed. The pathways leading to bimolecular product channels are kinetically unfavorable. Formation and subsequent stabilization of an ICNO adduct species appears to dominate the reaction, in agreement with the experimentally observed pressure dependent rate constants.

  9. Reaction Automata

    OpenAIRE

    Okubo, Fumiya; Kobayashi, Satoshi; YOKOMORI, Takashi

    2011-01-01

    Reaction systems are a formal model that has been introduced to investigate the interactive behaviors of biochemical reactions. Based on the formal framework of reaction systems, we propose new computing models called reaction automata that feature (string) language acceptors with multiset manipulation as a computing mechanism, and show that reaction automata are computationally Turing universal. Further, some subclasses of reaction automata with space complexity are investigated and their la...

  10. Reaction of Projectiles with Targets during Hypervelocity Impact

    Science.gov (United States)

    Russell, Rod; Bless, Stephan; Persad, Chadee; Manthiram, Karthish

    2009-06-01

    Hollow tungsten projectiles were filled with bismuth oxide or copper and shot into aluminum blocks at 2200 m/s. The blocks were cut open, and the contents and morphology of the penetration channels were examined. In the case of copper fill, the channel was found to be filled with a black foam containing closed-cell bubbles. X-ray diffraction revealed the presence of CuAl2, indicating reaction with the aluminum target. In the case of bismuth oxide, there was little foam, but the penetration channel walls had many craters, which contained nodules of bismuth metal, again indicating reaction with the target. There were variations in crater diameter apparently corresponding to the onset and termination of the reactions. The exothermic nature of the reactions produced cracks in the target blocks.

  11. Defect reaction network in Si-doped InAs. Numerical predictions.

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, Peter A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-05-01

    This Report characterizes the defects in the def ect reaction network in silicon - doped, n - type InAs predicted with first principles density functional theory. The reaction network is deduced by following exothermic defect reactions starting with the initially mobile interstitial defects reacting with common displacement damage defects in Si - doped InAs , until culminating in immobile reaction p roducts. The defect reactions and reaction energies are tabulated, along with the properties of all the silicon - related defects in the reaction network. This Report serves to extend the results for the properties of intrinsic defects in bulk InAs as colla ted in SAND 2013 - 2477 : Simple intrinsic defects in InAs : Numerical predictions to include Si - containing simple defects likely to be present in a radiation - induced defect reaction sequence . This page intentionally left blank

  12. Direct Measurements of Half-Cycle Reaction Heats during Atomic Layer Deposition by Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lownsbury, James M. [Department; Gladden, James A. [Department; Campbell, Charles T. [Department; Department; Kim, In Soo [Materials; Martinson, Alex B. F. [Materials

    2017-10-05

    We introduce a new high-temperature adsorption calorimeter that approaches the ideal limit of a heat detector whereby the signal at any time is proportional to the heat power being delivered to the sample and prove its sensitivity for measuring pulse-to-pulse heats of half-reactions during atomic layer deposition (ALD) at 400 K. The heat dynamics of amorphous Al2O3 growth via sequential self-limiting surface reaction of trimethylaluminum (TMA) and H2O is clearly resolved. Calibration enables quantitation of the exothermic TMA and H2O half-reactions with high precision, -343 kJ/mol TMA and -251 kJ/mol H2O, respectively. A time resolution better than 1 ms is demonstrated, allowing for the deconvolution of at least two distinct surface reactions during TMA microdosing. It is further demonstrated that this method can provide the heat of reaction versus extent of reaction during each precursors half-reaction, thus providing even richer mechanistic information on the surface processes involved. The broad applicability of this novel calorimeter is demonstrated through excellent signal-to-noise ratios of less exothermic ALD half-reactions to produce TiO2 and MnO.

  13. A photoionization study of the formation of NO2/+/ by reaction of excited O2/+/ ions with NO

    Science.gov (United States)

    Ajello, J. M.; Rayermann, P.

    1977-01-01

    Photoionization mass spectrometer results are presented for the first observation of the ion-molecule reaction in which O2(+) + NO yields NO2(+) + O. The reaction is energetically possible for ground state O2(+) ions in the lowest vibrational level. Photoionization efficiency curves for NO(+), O2(+), and NO2(+) are presented and compared, with special emphasis on autoionization features. In addition to the production of NO2(+) by the cited reaction, there is also a possibility for NO2(+) formation by the process O2 + NO(+) yielding NO2(+) + O. This reaction is calculated to be exothermic for incident photon energies of 11.73 eV.

  14. A one-step reaction for the rapid identification of Lactobacillus mindensis, Lactobacillus panis, Lactobacillus paralimentarius, Lactobacillus pontis and Lactobacillus frumenti using oligonucleotide primers designed from the 16S-23S rRNA intergenic sequences

    National Research Council Canada - National Science Library

    Ferchichi, M; Valcheva, R; Prévost, H; Onno, B; Dousset, X

    2008-01-01

    ...) were designed to rapidly discriminate between Lactobacillus mindensis, Lactobacillus panis, Lactobacillus paralimentarius, Lactobacillus pontis and Lactobacillus frumenti species recently isolated from French sourdough...

  15. Exothermic-Endothermic Transition in the Titration of Poly(allylamine chloride) with Sodium Hexametaphoshate Associated with a Change in the Proton Release Regime.

    Science.gov (United States)

    Maechling, Clarisse; Ball, Vincent

    2016-05-26

    The formation of complexes (aggregates) between oppositely charged macromolecular species or between macromolecular species and multivalent ions is a fascinating fundamental research topic that allows one to understand fundamental processes in biology and in polymer science. In addition interpolyelectrolyte complexes hold by strong interactions and polyelectrolyte coacervates in which the stabilizing interactions are weaker find many applications in food and in colloidal science. The interactions between oppositely charged species are usually investigated as a function of intensive variables like the temperature, the pH, the ionic strength, and parameters related to the charged species themselves (molecular mass, charge density, charge distribution, and so forth). It appeared however in the past few years that the interaction kinetics is also of fundamental importance; a fast mixing of the interacting species can lead to the formation of frozen and out-of-equilibrium structures. The present investigation is aimed to study the interactions between a small polyphosphate (sodium hexametaphosphate) (HMP) and a linear polyamine (poly(allylamine hydrochloride)) (PAH) from both a thermodynamic and kinetic point of view as a function of the ionic strength (in NaCl solutions). It is found, unexpectedly, that the interaction is of biphasic nature with a first exothermic regime followed by an endothermic regime. The transition between both regimes is ionic strength independent between 10 and 2000 mM emphasizing the strong interactions between both species. It occurs at a charge ratio of about 0.4 between the number of negative and positive charges and is correlated with proton release in the exothermic regime and a proton uptake in the endothermic regime. When HMP solutions are titrated in PAH solutions the turbidity of the mixtures is not the same as that obtained during the reverse titration at a given charge ratio, emphasizing the difficulty to establish an "equilibrium

  16. Drug Reactions

    Science.gov (United States)

    ... or diabetes. But medicines can also cause unwanted reactions. One problem is interactions, which may occur between ... more serious. Drug allergies are another type of reaction. They can be mild or life-threatening. Skin ...

  17. Accurate Reaction Enthalpies and Sources of Error in DFT Thermochemistry for Aldol, Mannich, and α-Aminoxylation Reactions

    Science.gov (United States)

    Wheeler, Steven E.; Moran, Antonio; Pieniazek, Susan N.

    2009-01-01

    Enthalpies for bond-forming reactions that are subject to organocatalysis have been predicted using the high-accuracy CBS-QB3 model chemistry and six DFT functionals. Reaction enthalpies were decomposed into contributions from changes in bonding and other intramolecular effects via the hierarchy of homodesmotic reactions. The order of the reaction exothermicities (aldol < Mannich ≈ α-aminoxylation) arises primarily from changes in formal bond types mediated by contributions from secondary intramolecular interactions. In each of these reaction types, methyl substitution at the β- and γ-positions stabilizes the products relative to the unsubstituted case. The performance of six DFT functionals (B3LYP, B3PW91, B1B95, MPW1PW91, PBE1PBE, and M06-2X), MP2, and SCS-MP2 has been assessed for the prediction of these reaction enthalpies. Even though the PBE1PBE and M06-2X functionals perform well for the aldol and Mannich reactions, errors roughly double when these functionals are applied to the α-aminoxylation reactions. On the other hand, B3PW91 and B1B95, which offer modest accuracy for the aldol and Mannich reactions, yield reliable predictions for the two α-aminoxylation reactions. The excellent performance of the M06-2X and PBE1PBE functionals for aldol and Mannich reactions stems from the cancellation of sizeable errors arising from inadequate descriptions of the underlying bond transformations and intramolecular interactions. SCS-MP2/cc-pVTZ performs most consistently across these three classes of reactions, although the reaction exothermicities are systematically underestimated by 1–3 kcal mol−1. Conventional MP2, when paired with the cc-pVTZ basis set, performs somewhat better than SCS-MP2 for some of these reactions, particularly the α-aminoxylations. Finally, the merits of benchmarking DFT functionals for the set of simple chemically meaningful transformations underlying all bond-forming reactions are discussed. PMID:19711937

  18. Rapid mixing kinetic techniques.

    Science.gov (United States)

    Martin, Stephen R; Schilstra, Maria J

    2013-01-01

    Almost all of the elementary steps in a biochemical reaction scheme are either unimolecular or bimolecular processes that frequently occur on sub-second, often sub-millisecond, time scales. The traditional approach in kinetic studies is to mix two or more reagents and monitor the changes in concentrations with time. Conventional spectrophotometers cannot generally be used to study reactions that are complete within less than about 20 s, as it takes that amount of time to manually mix the reagents and activate the instrument. Rapid mixing techniques, which generally achieve mixing in less than 2 ms, overcome this limitation. This chapter is concerned with the use of these techniques in the study of reactions which reach equilibrium; the application of these methods to the study of enzyme kinetics is described in several excellent texts (Cornish-Bowden, Fundamentals of enzyme kinetics. Portland Press, 1995; Gutfreund, Kinetics for the life sciences. Receptors, transmitters and catalysis. Cambridge University Press, 1995).There are various ways to monitor changes in concentration of reactants, intermediates and products after mixing, but the most common way is to use changes in optical signals (absorbance or fluorescence) which often accompany reactions. Although absorbance can sometimes be used, fluorescence is often preferred because of its greater sensitivity, particularly in monitoring conformational changes. Such methods are continuous with good time resolution but they seldom permit the direct determination of the concentrations of individual species. Alternatively, samples may be taken from the reaction volume, mixed with a chemical quenching agent to stop the reaction, and their contents assessed by techniques such as HPLC. These methods can directly determine the concentrations of different species, but are discontinuous and have a limited time resolution.

  19. Rapid Prototyping

    Science.gov (United States)

    1999-01-01

    Javelin, a Lone Peak Engineering Inc. Company has introduced the SteamRoller(TM) System as a commercial product. The system was designed by Javelin during a Phase II NASA funded small commercial product. The purpose of the invention was to allow automated-feed of flexible ceramic tapes to the Laminated Object Manufacturing rapid prototyping equipment. The ceramic material that Javelin was working with during the Phase II project is silicon nitride. This engineered ceramic material is of interest for space-based component.

  20. Rate constants and branching ratios for the reaction of CH radicals with NH3: a combined experimental and theoretical study.

    Science.gov (United States)

    Blitz, Mark A; Talbi, Dahbia; Seakins, Paul W; Smith, Ian W M

    2012-06-21

    The reaction between CH radicals and NH(3) molecules is known to be rapid down to at least 23 K {at which temperature k = (2.21 ± 0.17) × 10(-10) cm(3) molecule(-1) s(-1): Bocherel ; et al. J. Phys. Chem. 1996, 100, 3063}. However, there have been only limited theoretical investigations of this reaction and its products are not known. This paper reports (i) ab initio quantum chemical calculations on the energy paths that lead to various reaction products, (ii) calculations of the overall rate constant and branching ratios to different products using transition state and master equation methods, and (iii) an experimental determination of the H atom yield from the reaction. The ab initio calculations show that reaction occurs predominantly via the initial formation of a datively bound HC-NH(3) complex and reveal low energy pathways to three sets of reaction products: H(2)CNH + H, HCNH(2) + H, and CH(3) + NH. The transition state calculations indicate the roles of "outer" and "inner" transition states and yield rate constants between 20 and 320 K that are in moderate agreement with the experimental values. These calculations and those using the master equation approach show that the branching ratio for the most exothermic reaction, to H(2)CNH + H, is ca. 96% throughout the temperature range covered by the calculations, with those to HCNH(2) + H and CH(3) + NH being (4 ± 3)% and <0.3%, respectively. In the experiments, multiple photon dissociation of CHBr(3) was used to generate CH radicals and laser-induced fluorescence at 121.56 nm (VUV-LIF) was employed to observe H atoms. By comparing signals from CH + NH(3) with those from CH + CH(4), where the yield of H atoms is known to be unity, it is possible to estimate that the yield of H atoms from CH + NH(3) is equal to 0.89 ± 0.07 (2σ), in satisfactory agreement with the theoretical estimate.

  1. Reaction of SiF4 with Al Metal

    Science.gov (United States)

    Xie, Xiaobing; Lau, Kai; Sanjurjo, Angel; Alkhudhiri, Abdullah I.; Alzaben, Abdullah; Alabbad, Waiel

    2017-03-01

    The reaction of SiF4 gas with aluminum (Al) was studied at temperatures ranging from room temperature to 1723 K (1450 °C). Although thermochemical estimates indicate that reactions throughout the temperature range should be thermodynamically favorable, we found that no reaction takes place appreciably until Al is heated to around 1473 K (1200 °C). The reaction products consist of fine powders of Si, Al, and AlF3. Some of the reaction products were transported away from the reaction zone by strong convection currents resulting from the exothermic reaction. Even at approximately 1673 K (1400 °C), the reaction rate is slow and a significant amount of Al remains unreacted. When NaF powders were used to line the graphite reactor, NaAlF4, AlF3, and Si powders were observed on the upper cooler walls of the reactor, and Si whiskers were formed just above the Al-Si alloy globule on the bottom of the crucible. We found evidence of the formation of AlF and SiF2 vapor species in the reaction zone, which then disproportionated along the cooler walls of the reactor, generating powders of Al and Si and regenerating condensable AlF3 and SiF4 gas, respectively.

  2. Reaction catalyst for the elimination of oxyhydrogen gas in lead--acid storage batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lahme, N.; Sassmannshausen, G.

    1978-12-12

    A reaction catalyst for the recombination of the oxyhydrogen gas produced by lead--acid storage batteries into water in a controlled, exothermic reaction is described. The catalyst element is a solid rod element with a central heat-conducting core. The catalyst rod is positioned inside a gas-tight housing in communication with the battery gas space. This rod element is produced by a fabricating method in which granular catalyst carrier material is worked into a paste which is then shaped and dried, the metallic catalyst being deposited on the surface of the carrier grains. 4 figures, 1 table.

  3. The Reaction of Allyl Isothiocyanate with Hydroxyl/Water and β-Cyclodextrin Using Ultraviolet Spectrometry

    Directory of Open Access Journals (Sweden)

    Zi-Tao Jiang

    2006-01-01

    Full Text Available The reaction of allyl isothiocyanate (AITC with hydroxyl/water and β-cyclodextrin (β-CD in different acidic-alkaline media has been investigated by ultraviolet spectrometry. The kinetic parameters of the reaction were measured. It was found that after AITC translating into thiourea, the absorption peak shifted from 240 to 226 nm and the molar absorptivity increased about 16 times. The reaction can be seen as a pseudo first order reaction because the concentration of hydroxyl was constant. β-CD can inhibit the reaction of AITC with hydroxyl/water, i.e. the hydrolysis of AITC. The formation constant (Ka and thermodynamic parameters of the complex reaction were calculated. Ka decreased with the increase of temperature. The experimental results indicated that the inclusive process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution.

  4. A mechanochemical study of the effects of compression on a Diels-Alder reaction

    Science.gov (United States)

    Jha, Sanjiv K.; Brown, Katie; Todde, Guido; Subramanian, Gopinath

    2016-08-01

    We examine the effects of compressive external forces on the mechanisms of the parent Diels-Alder (DA) reaction between butadiene and ethylene. Reaction pathways and transition states were calculated using the nudged elastic band method within a mechanochemical framework at the CASSCF(6,6)/6-31G**, as well as the B3LYP/6-311++G** levels of theory. Our results suggest that compressive hydrostatic pressure lowers the energy barrier for the parent DA reaction while suppressing the undesirable side reaction, thereby leading to a direct increase in the yield of cyclohexene. Compressive pressure also increases the exothermicity of the parent DA reaction, which would lead to increased temperatures in a reaction vessel and thereby indirectly increase the yield of cyclohexene. Our estimates indicate that the compression used in our study corresponds to a range of 68 MPa-1410 MPa.

  5. A rapid and sensitive diagnosis of bovine leukaemia virus infection using the nested shuttle polymerase chain reaction Diagnóstico rápido e sensível da infecção com o vírus da Leucemia Bovina através de Shuttle Nested Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    Ester T. González

    1999-04-01

    Full Text Available Bovine leukaemia virus (BLV is the causative agent of enzootic bovine leukosis (EBL. In Argentina, where a program to eradicate EBL has been introduced, sensitive and reliable diagnosis has attained high priority. Although the importance of the agar gel immunodiffusion test remains unchanged for routine work, an additional diagnostic technique is necessary to confirm cases of sera with equivocal results or of calves carrying maternal antibodies.Utilizing a nested shuttle polymerase chain reaction, the proviral DNA was detected from cows experimentally infected with as little as 5 ml of whole blood from BLV seropositive cows that were nonetheless normal in haematological terms. It proved to be a very sensitive technique, since it rapidly revealed the presence of the provirus, frequently at 2 weeks postinoculation and using a two-round procedure of nested PCR taking only 3 hours. Additionally, the primers used flanked a portion of the viral genome often employed to differentiate BLV type applying BamHI digestion. It is concluded that this method might offer a highly promising diagnostic tool for BLV infection.O Vírus da leucemia bovina (BLV é o agente causal da Leucose Enzoótica Bovina (EBL. Na Argentina, iniciou-se um programa de erradicação da EBL. Neste estágio, é prioritário possuir uma ferramenta de diagnóstico confiável. Embora seja indiscutível a importância do teste de agar gel imunodifusão, empregado rotineiramente no diagnóstico serológico da EBL, faz-se necessária uma técnica de diagnóstico adicional capaz de confirmar os resultados duvidosos. Foi possivel detectar ADN proviral aplicando Nested-PCR em novilhos experimentalmente infectados com pequenas doses de sangue total (5ml obtidas de um bovino BLV soropositivo. Esta técnica, cujo procedimento leva 3 horas, demonstrou ser muito sensível, uma vez que foi capaz de detectar a presença do provirus duas semanas após a inoculação. Os primers utilizados são os que

  6. Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-02-01

    Full Text Available Metal/fluoropolymer composites are a category of energetic structural materials that release energy through exothermic chemical reactions initiated under highly dynamic loadings. In this paper, the chemical reaction mechanism of PTFE (polytetrafluoroethylene/Ti/W composites is investigated through thermal analysis and composition analysis. These composites undergo exothermic reactions at 510 °C to 600 °C, mainly producing TiFx. The tungsten significantly reduces the reaction heat due to its inertness. In addition, the dynamic compression properties and impact-induced reaction behaviors of PTFE/Ti/W composites with different W content prepared by pressing and sintering are studied using Split Hopkinson Pressure Bar and high speed photography. The results show that both the mechanical strength and the reaction degree are significantly improved with the increasing strain rate. Moreover, as W content increases, the mechanical strength is enhanced, but the elasticity/plasticity is decreased. The PTFE/Ti/W composites tend to become more inert with the increasing W content, which is reflected by the reduced reaction degree and the increased reaction threshold for the impact ignition.

  7. Experimental Study on Impact-Induced Reaction Characteristics of PTFE/Ti Composites Enhanced by W Particles.

    Science.gov (United States)

    Li, Yan; Wang, Zaicheng; Jiang, Chunlan; Niu, Haohao

    2017-02-13

    Metal/fluoropolymer composites are a category of energetic structural materials that release energy through exothermic chemical reactions initiated under highly dynamic loadings. In this paper, the chemical reaction mechanism of PTFE (polytetrafluoroethylene)/Ti/W composites is investigated through thermal analysis and composition analysis. These composites undergo exothermic reactions at 510 °C to 600 °C, mainly producing TiFx. The tungsten significantly reduces the reaction heat due to its inertness. In addition, the dynamic compression properties and impact-induced reaction behaviors of PTFE/Ti/W composites with different W content prepared by pressing and sintering are studied using Split Hopkinson Pressure Bar and high speed photography. The results show that both the mechanical strength and the reaction degree are significantly improved with the increasing strain rate. Moreover, as W content increases, the mechanical strength is enhanced, but the elasticity/plasticity is decreased. The PTFE/Ti/W composites tend to become more inert with the increasing W content, which is reflected by the reduced reaction degree and the increased reaction threshold for the impact ignition.

  8. Rapid detection of cytomegalovirus in bronchoalveolar lavage fluid and serum samples by polymerase chain reaction: correlation of virus isolation and clinical outcome for patients with human immunodeficiency virus infection

    DEFF Research Database (Denmark)

    Hansen, K K; Vestbo, Jørgen; Benfield, T

    1997-01-01

    Bronchoalveolar lavage (BAL) fluids and serum samples from 153 patients with pulmonary symptoms who were infected with human immunodeficiency virus (HIV) and underwent BAL were examined for the presence of cytomegalovirus (CMV) by conventional culture and by polymerase chain reaction (PCR...

  9. 3D Defect Localization on Exothermic Faults within Multi-Layered Structures Using Lock-In Thermography: An Experimental and Numerical Approach

    Directory of Open Access Journals (Sweden)

    Ji Yong Bae

    2017-10-01

    Full Text Available Micro-electronic devices are increasingly incorporating miniature multi-layered integrated architectures. However, the localization of faults in three-dimensional structure remains challenging. This study involved the experimental and numerical estimation of the depth of a thermally active heating source buried in multi-layered silicon wafer architecture by using both phase information from an infrared microscopy and finite element simulation. Infrared images were acquired and real-time processed by a lock-in method. It is well known that the lock-in method can increasingly improve detection performance by enhancing the spatial and thermal resolution of measurements. Operational principle of the lock-in method is discussed, and it is represented that phase shift of the thermal emission from a silicon wafer stacked heat source chip (SSHSC specimen can provide good metrics for the depth of the heat source buried in SSHSCs. Depth was also estimated by analyzing the transient thermal responses using the coupled electro-thermal simulations. Furthermore, the effects of the volumetric heat source configuration mimicking the 3D through silicon via integration package were investigated. Both the infrared microscopic imaging with the lock-in method and FE simulation were potentially useful for 3D isolation of exothermic faults and their depth estimation for multi-layered structures, especially in packaged semiconductors.

  10. Reactions of M(+)(H2O)n, n < 40, M = V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, with D2O reveal water activation in Mn(+)(H2O)n.

    Science.gov (United States)

    van der Linde, Christian; Beyer, Martin K

    2012-11-08

    Reactions of M(+)(H(2)O)(n), n hydrogen occurs. For manganese, HDO formation occurs in the size regime n ≈ 8-20. Additional experiments show that, in this size regime, Mn(+)(H(2)O)(n) is slowly converted into HMnOH(+)(H(2)O)(n-1) under the influence of room temperature blackbody radiation. The reaction is mildly exothermic; ΔH ≈ -21 ± 10 kJ mol(-1).

  11. Prediction of Tetraoxygen Reaction Mechanism with Sulfur Atom on the Singlet Potential Energy Surface

    Directory of Open Access Journals (Sweden)

    Ashraf Khademzadeh

    2014-01-01

    Full Text Available The mechanism of S+O4 (D2h reaction has been investigated at the B3LYP/6-311+G(3df and CCSD levels on the singlet potential energy surface. One stable complex has been found for the S+O4 (D2h reaction, IN1, on the singlet potential energy surface. For the title reaction, we obtained four kinds of products at the B3LYP level, which have enough thermodynamic stability. The results reveal that the product P3 is spontaneous and exothermic with −188.042 and −179.147 kcal/mol in Gibbs free energy and enthalpy of reaction, respectively. Because P1 adduct is produced after passing two low energy level transition states, kinetically, it is the most favorable adduct in the 1S+1O4 (D2h atmospheric reactions.

  12. Thermodynamic analysis of ANS binding to partially unfolded α-lactalbumin: correlation of endothermic to exothermic changeover with formation of authentic molten globules.

    Science.gov (United States)

    Kim, Ki Hyung; Yun, Soi; Mok, K H; Lee, E K

    2016-09-01

    A fluorescent reporter, 8-anilino-1-naphthalene sulfonic acid (ANS), can serve as a reference molecule for conformational transition of a protein because its aromatic carbons have strong affinity with hydrophobic cores of partially unfolded molten globules. Using a typical calcium-binding protein, bovine α-lactalbumin (BLA), as a model protein, we compared the ANS binding thermodynamics to the decalcified (10 mM EDTA treated) apo-BLA at two representative temperatures: 20 and 40 °C. This is because the authentic molten globule is known to form more heavily at an elevated temperature such as 40 °C. Isothermal titration calorimetry experiments revealed that the BLA-ANS interactions at both temperatures were entropy-driven, and the dissociation constants were similar on the order of 10(-4)  M, but there was a dramatic changeover in the binding thermodynamics from endothermic at 20 °C to exothermic at 40 °C. We believe that the higher subpopulation of authentic molten globules at 40 °C than 20 °C would be responsible for the results, which also indicate that weak binding is sufficient to alter the ANS binding mechanisms. We expect that the thermodynamic properties obtained from this study would serve as a useful reference for investigating the binding of other hydrophobic ligands such as oleic acid to apo-BLA, because oleic acid is known to have tumor-selective cytotoxicity when complexed with partially unfolded α-lactalbumin. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Rapid chemical separations

    CERN Document Server

    Trautmann, N

    1976-01-01

    A survey is given on the progress of fast chemical separation procedures during the last few years. Fast, discontinuous separation techniques are illustrated by a procedure for niobium. The use of such techniques for the chemical characterization of the heaviest known elements is described. Other rapid separation methods from aqueous solutions are summarized. The application of the high speed liquid chromatography to the separation of chemically similar elements is outlined. The use of the gas jet recoil transport method for nuclear reaction products and its combination with a continuous solvent extraction technique and with a thermochromatographic separation is presented. Different separation methods in the gas phase are briefly discussed and the attachment of a thermochromatographic technique to an on-line mass separator is shown. (45 refs).

  14. Reaction Time and Anticipation Time: Effects of Development.

    Science.gov (United States)

    Thomas, Jerry R.; And Others

    1981-01-01

    Results of a study indicated that, as age increased from seven to 20 years, reaction time decreased, with males having a more rapid reaction time than females. Beginning at age 10 or 11, subjects developed better motor plans and relied less on rapid reaction time to achieve good anticipation time. (FG)

  15. Synthesis of renewable diesel through hydrodeoxygenation reaction from nyamplung oil (Calophyllum Inophyllum oil) using NiMo/Z and NiMo/C catalysts with rapid heating and cooling method

    Science.gov (United States)

    Susanto, B. H.; Prakasa, M. B.; Shahab, M. H.

    2016-11-01

    The synthesis of metal nanocrystal was conducted by modification preparation from simple heating method which heating and cooling process run rapidly. The result of NiMo/Z 575 °C characterizations are 33.73 m2/gram surface area and 31.80 nm crystal size. By used NiMo/C 700 °C catalyst for 30 minutes which had surface area of 263.21 m2/gram, had 31.77 nm crystal size, and good morphology, obtained catalyst with high activity, selectivity, and stability. After catalyst activated, synthesis of renewable diesel performed in hydrogenation reactor at 375 °C, 12 bar, and 800 rpm. The result of conversion was 81.99%, yield was 68.08%, and selectivity was 84.54%.

  16. Chlorine dioxide-induced and Congo red-inhibited Marangoni effect on the chlorite-trithionate reaction front

    Science.gov (United States)

    Liu, Yang; Ren, Xingfeng; Pan, Changwei; Zheng, Ting; Yuan, Ling; Zheng, Juhua; Gao, Qingyu

    2017-10-01

    Hydrodynamic flows can exert multiple effects on an exothermal autocatalytic reaction, such as buoyancy and the Marangoni convection, which can change the structure and velocity of chemical waves. Here we report that in the chlorite-trithionate reaction, the production and consumption of chlorine dioxide can induce and inhibit Marangoni flow, respectively, leading to different chemo-hydrodynamic patterns. The horizontal propagation of a reaction-diffusion-convection front was investigated with the upper surface open to the air. The Marangoni convection, induced by gaseous chlorine dioxide on the surface, produced from chlorite disproportionation after the proton autocatalysis, has the same effect as the heat convection. When the Marangoni effect is removed by the reaction of chlorine dioxide with the Congo red (CR) indicator, an oscillatory propagation of the front tip is observed under suitable conditions. Replacing CR with bromophenol blue (BPB) distinctly enhanced the floating, resulting in multiple vortexes, owing to the coexistence between BPB and chlorine dioxide. Using the incompressible Navier-Stokes equations coupled with reaction-diffusion and heat conduction equations, we numerically obtain various experimental scenarios of front instability for the exothermic autocatalytic reaction coupled with buoyancy-driven convection and Marangoni convection.

  17. Effect of Particle Morphology on Critical Conditions for Shock-Initiated Reactions in Titanium-Silicon Powder Mixtures

    Science.gov (United States)

    Frost, David; Jette, Francois; Goroshin, Samuel; Higgins, Andrew; Lee, Julian

    2009-06-01

    The effect of titanium particle morphology on the shock sensitivity of titanium-silicon powder mixtures has been investigated experimentally. The powder mixtures were tested in a planar recovery capsule, with the shock loading produced by a high explosive Tetryl booster charge placed on top of the capsule and a PMMA attenuator. Reactions were not observed for stoichiometric mixtures of large (75 -- 106 μm), spherical Ti particles with fine (effects which lowered the temperature for the onset of exothermic reaction of the shocked sample by about 80^oC.

  18. Prospective evaluation of a high multiplexing real-time polymerase chain reaction array for the rapid identification and characterization of bacteria causative of nosocomial pneumonia from clinical specimens: a proof-of-concept study.

    Science.gov (United States)

    Roisin, S; Huang, T-D; de Mendonça, R; Nonhoff, C; Bogaerts, P; Hites, M; Delaere, B; Hamels, S; de Longueville, F; Glupczynski, Y; Denis, O

    2017-09-27

    The purpose of this study was evaluation of the VAPChip assay based on the "Rapid-Array-PCR-technology" which targets 13 respiratory pathogens and 24 β-lactam resistance genes directly on respiratory clinical specimens. The first step included analysis of 45 respiratory specimens in order to calibrate and determine the threshold for target genes. The second prospective step involved 85 respiratory samples from patients suspected of nosocomial pneumonia collected in two academic hospitals over an 8-month period. Results of the VAPChip assay were compared to routine methods. The first step showed a large proportion of positive signals for H. influenzae and/or S. pneumoniae. For identification, discrepancies were observed in seven samples. Thresholds were adapted and two probes were re-designed to create a new version of the cartridge. In the second phase, sensitivity and specificity of the VAPchip for bacterial identification were 72.9% and 99.1%, respectively. Seventy (82%) pathogens were correctly identified by both methods. Nine pathogens detected by the VAPChip were culture negative and 26 pathogens identified by culture were VAPChip negative. For resistance mechanisms, 11 probes were positive without identification of pathogens with an antimicrobial-susceptibility testing compatible by culture. However, the patient's recent microbiological history was able to explain most of these positive signals. The VAPChip assay simultaneously detects different pathogens and resistance mechanisms directly from clinical samples. This system seems very promising but the extraction process needs to be automated for routine implementation. This kind of rapid point-of-care automated platform permitting a syndromic approach will be the future challenge in the management of infectious diseases.

  19. The effect of intramolecular quantum modes on free energy relationships for electron transfer reactions

    DEFF Research Database (Denmark)

    Ulstrup, Jens; Jortner, Joshua

    1975-01-01

    -frequency intramolecular degrees of feedom on the free energy relationship for series of closely related reactions was investigated for various model systems involving displacement of potential energy surfaces, frequency shift, and anharmonicity effects. The free energy plots are generally found to pass through a maximum...... and to be asymmetric with a slower decrease in the transition probability with increasing energy of reaction. For high-frequency intramolecular modes this provides a rationalization of the experimental observation of ''activationless'' regions. Isotope effects are discussed as also are the oscillatory free energy......A general quantum mechanical description of exothermic electron transfer reactions is formulated by treating such reactions as the nonradiative decay of a ''supermolecule'' consisting of the electron donor, the electron acceptor, and the polar solvent. In particular, the role of the high...

  20. Upper limit of a tunneling reaction rate for D-+H2 →HD+H-

    Science.gov (United States)

    Endres, Eric S.; Lakhamanskaya, Olga; Simpson, Malcolm; Spieler, Steffen; Wester, Roland

    2017-02-01

    The exothermic proton transfer reaction D-+H2→ HD+H- is known to proceed over a barrier of about 0.33 eV. Here we investigate whether this reaction may occur at low temperatures via tunneling through this barrier. The experiments were carried out in a cryogenic 22-pole ion trap, which provides a high sensitivity for slow ion-molecule reactions. Our experiments show no sign of the tunneling reaction with an upper limit to the rate coefficient of 2.6 ×10-18 cm3/s obtained from the decrease of the D- signal and 9 ×10-19 cm3/s from the absence of an increase of H-. Background impurities were identified to be the main limitation of the sensitivity.

  1. Rapid synthesis of beta zeolites

    Science.gov (United States)

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

    2015-08-18

    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  2. cycloaddition reactions

    Indian Academy of Sciences (India)

    Unknown

    models of regioselectivity in pericyclic reactions. In addition, local hard and soft acid base (HSAB) princi- ples have been also employed to predict the observed regioselectivity.2 In recent years, the conceptual density functional theory has been remarkably successful in explaining the reactivity and site selectivity.3 The.

  3. Mathematical Model of Synthesis Catalyst with Local Reaction Centers

    Directory of Open Access Journals (Sweden)

    I. V. Derevich

    2017-01-01

    Full Text Available The article considers a catalyst granule with a porous ceramic passive substrate and point active centers on which an exothermic synthesis reaction occurs. A rate of the chemical reaction depends on the temperature according to the Arrhenius law. Heat is removed from the pellet surface in products of synthesis due to heat transfer. In our work we first proposed a model for calculating the steady-state temperature of a catalyst pellet with local reaction centers. Calculation of active centers temperature is based on the idea of self-consistent field (mean-field theory. At first, it is considered that powers of the reaction heat release at the centers are known. On the basis of the found analytical solution, which describes temperature distribution inside the granule, the average temperature of the reaction centers is calculated, which then is inserted in the formula for heat release. The resulting system of transcendental algebraic equations is transformed into a system of ordinary differential equations of relaxation type and solved numerically to achieve a steady-state value. As a practical application, the article considers a Fischer-Tropsch synthesis catalyst granule with active cobalt metallic micro-particles. Cobalt micro-particles are the centers of the exothermic reaction of hydrocarbons macromolecular synthesis. Synthesis occurs as a result of absorption of the components of the synthesis gas on metallic cobalt. The temperature distribution inside the granule for a single local center and reaction centers located on the same granule diameter is found. It was found that there is a critical temperature of reactor exceeding of which leads to significant local overheating of the centers - thermal explosion. The temperature distribution with the local reaction centers is qualitatively different from the granule temperature, calculated in the homogeneous approximation. It is shown that, in contrast to the homogeneous approximation, the

  4. Discrimination between mild and severe Citrus tristeza virus isolates with a rapid and highly specific real-time reverse transcription-polymerase chain reaction method using TaqMan LNA probes.

    Science.gov (United States)

    Ruiz-Ruiz, S; Moreno, P; Guerri, J; Ambrós, S

    2009-03-01

    Severe isolates of Citrus tristeza virus (CTV) inducing seedling yellows (SY) and/or stem pitting (SP) in grapefruit or sweet orange are a major threat for the citrus industry worldwide. Identification of these CTV variants was achieved by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) using a general primer set and three TaqMan locked nucleic acids (LNA) probes targeting sequences characteristic of severe, mild (non-SY, non-SP), and T36-like isolates. Successful amplification was achieved from fresh or silica-desiccated CTV-infected samples and all isolates but one reacted with one or more probes. Standard curves using RNA transcripts homologous to the three probes allowed a reproducible quantitative assay, with a wide dynamic range of detection starting with 10(2) copies. RT-PCR assays with homologous and heterologous transcript RNA mixes demonstrated that each probe reacted only with its cognate sequence which was detected even at ratios below 2.5%. Analysis of 56 pathogenically distinct CTV isolates from 20 countries showed that mild isolates reacted only with the mild probe, whereas severe SP and SY isolates reacted with the severe-SP or the T36-like probes, respectively, and often with a second probe. This procedure can be useful to identify and control potentially dangerous CTV isolates in areas affected only by mild isolates.

  5. Spectroscopy and reaction kinetics of HCO

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yili

    1989-01-01

    The high-resolution infrared spectrum of the C-H stretching fundamental of HCO has been studied by means of infrared flash kinetic spectroscopy. HCO was generated by flash photolysis of acetaldehyde or formaldehyde using a 308 nm (XeCl) excimer laser. The transient absorption was probed with an infrared difference frequency laser system. The high resolution spectra obtained were assigned and fitted with rotational, spin-rotational, and centrifugal distortion constants. The ..nu../sub 1/ band origin is 2434.48 cm/sup /minus/1/. New ground state constants have been derived from a least-squares fit combining the ..nu../sub 1/ data with previous microwave and FIR LMR measurements. A new set of spectroscopic constants for the (1, 0, 0) state, the equilibrium rotational constants, and the orientation of the transition dipole moment are also reported. The kinetics and product branching ratios of the HCO + NO/sub 2/ reaction have been studied using visible and infrared laser flash kinetic spectroscopy. The rate constant for the disappearance of HCO radical at 296 K is (5.7 +- 0.9) /times/ 10/sup /minus/11/ cm/sup 3/ molec/sup /minus/1/ sec/sup /minus/1/, and it is independent of the pressure of SF/sub 6/ buffer gas up to 700 torr. Less than 10% of the reaction goes through the most exothermic product channel, HNO + CO/sub 2/. The product channel, H + CO/sub 2/ + NO, is responsible for 52% of the reaction. HONO has been observed, though not quantitatively, as a reaction product corresponding to the HONO + CO channel. 51 refs., 21 figs., 8 tabs.

  6. Acoustic Resonance Reaction Control Thruster (ARCTIC) Project

    Data.gov (United States)

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

  7. Reactions of carbon atoms in pulsed molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Reisler, H. [Univ. of Southern California, Los Angeles (United States)

    1993-12-01

    This research program consists of a broad scope of experiments designed to unravel the chemistry of atomic carbon in its two spin states, P and D, by using well-controlled initial conditions and state-resolved detection of products. Prerequisite to the proposed studies (and the reason why so little is known about carbon atom reactions), is the development of clean sources of carbon atoms. Therefore, in parallel with the studies of its chemistry and reaction dynamics, the authors continuously explore new, state-specific and efficient ways of producing atomic carbon. In the current program, C({sup 3}P) is produced via laser ablation of graphite, and three areas of study are being pursued: (i) exothermic reactions with small inorganic molecules (e.g., O{sub 2}, N{sub 2}O, NO{sub 2}) that can proceed via multiple pathways; (ii) the influence of vibrational and translational energy on endothermic reactions involving H-containing reactants that yield CH products (e.g., H{sub 2}O H{sub 2}CO); (iii) reactions of C({sup 3}P) with free radicals (e.g., HCO, CH{sub 3}O). In addition, the authors plan to develop a source of C({sup 1}D) atoms by exploiting the pyrolysis of diazotetrazole and its salts in the ablation source. Another important goal involves collaboration with theoreticians in order to obtain relevant potential energy surfaces, rationalize the experimental results and predict the roles of translational and vibrational energies.

  8. Rotational dependence of the proton-transfer reaction HBr+ + CO2 → HOCO+ + Br. II. Comparison of HBr+ (2Π(3/2)) and HBr+ (2Π(1/2)).

    Science.gov (United States)

    Paetow, Lisa; Unger, Franziska; Beutel, Bernd; Weitzel, Karl-Michael

    2010-12-21

    The effects of reactant ion rotational excitation on the exothermic proton-transfer reactions of HBr(+)((2)Π(1/2)) and DBr(+)((2)Π(1/2)), respectively, with CO(2) were studied in a guided ion beam apparatus. Cross sections are presented for collision energies in the center of mass system E(c.m.) in the range of 0.23 to 1.90 eV. The HBr(+)/DBr(+) ions were prepared in a state-selective manner by resonance enhanced multiphoton ionization. The mean rotational energy was varied from 3.4 to 46.8 meV for HBr(+)((2)Π(1/2)) and from 1.8 to 40.9 meV for DBr(+)((2)Π(1/2)). Both reactions studied are inhibited by collision energy, as expected for exothermic reactions. For all collision energies considered, the cross section decreases with increasing rotational energy of the ion, but the degree of the rotational dependence differs depending on the collision energy. For E(c.m.) = 0.31 eV, the cross sections of the deuteron transfer are significantly larger than those of the proton transfer. For higher E(c.m.) they differ very little. The current results for the exothermic proton transfer are systematically compared to previously published data for the endothermic proton transfer starting from HBr(+)((2)Π(3/2)) [L. Paetow et al., J. Chem. Phys. 132, 174305 (2010)]. Additional new data regarding the latter reaction are presented to further confirm the conclusions. The dependences on rotational excitation found cannot be explained by the corresponding change in the total energy of the system. For both the endothermic and the exothermic reaction, the cross section is maximized for the smallest rotational energy, at least well above the threshold.

  9. Cold-Curing Structural Epoxy Resins: Analysis of the Curing Reaction as a Function of Curing Time and Thickness.

    Science.gov (United States)

    Corcione, Carola Esposito; Freuli, Fabrizio; Frigione, Mariaenrica

    2014-09-22

    The curing reaction of a commercial cold-curing structural epoxy resin, specifically formulated for civil engineering applications, was analyzed by thermal analysis as a function of the curing time and the sample thickness. Original and remarkable results regarding the effects of curing time on the glass transition temperature and on the residual heat of reaction of the cold-cured epoxy were obtained. The influence of the sample thickness on the curing reaction of the cold-cured resin was also deeply investigated. A highly exothermal reaction, based on a self-activated frontal polymerization reaction, was supposed and verified trough a suitable temperature signal acquisition system, specifically realized for this measurement. This is one of the first studies carried out on the curing behavior of these peculiar cold-cured epoxy resins as a function of curing time and thickness.

  10. Monitoring mass transport in heterogeneously catalyzed reactions by field-gradient NMR for assessing reaction efficiency in a single pellet.

    Science.gov (United States)

    Buljubasich, L; Blümich, B; Stapf, S

    2011-09-01

    An important aspect in assessing the performance of a catalytically active reactor is the accessibility of the reactive sites inside the individual pellets, and the mass transfer of reactants and products to and from these sites. Optimal design often requires a suitable combination of micro- and macropores in order to facilitate mass transport inside the pellet. In an exothermic reaction, fluid exchange between the pellet and the surrounding medium is enhanced by convection, and often by the occurrence of gas bubbles. Determining mass flow in the vicinity of a pellet thus represents a parameter for quantifying the reaction efficiency and its dependence on time or external reaction conditions. Field gradient Nuclear Magnetic Resonance (NMR) methods are suggested as a tool for providing parameters sensitive to this mass flow in a contact-free and non-invasive way. For the example of bubble-forming hydrogen peroxide decomposition in an alumina pellet, the dependence of the mean-squared displacement of fluid molecules on spatial direction, observation time and reaction time is presented, and multi-pulse techniques are employed in order to separate molecular displacements from coherent and incoherent motion on the timescale of the experiment. The reaction progress is followed until the complete decomposition of H2O2. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Reactions between cold methyl halide molecules and alkali-metal atoms

    CERN Document Server

    Lutz, Jesse J

    2013-01-01

    We investigate the potential energy surfaces and activation energies for reactions between methyl halide molecules CH$_{3}X$ ($X$ = F, Cl, Br, I) and alkali-metal atoms $A$ ($A$ = Li, Na, K, Rb) using high-level {\\it ab initio} calculations. We examine the anisotropy of each intermolecular potential energy surface (PES) and the mechanism and energetics of the only available exothermic reaction pathway, ${\\rm CH}_{3}X+A\\rightarrow{\\rm CH}_{3}+AX$. The region of the transition state is explored using two-dimensional PES cuts and estimates of the activation energies are inferred. Nearly all combinations of methyl halide and alkali-metal atom have positive barrier heights, indicating that reactions at low temperatures will be slow.

  12. Molecular Dynamics Simulations of the First Reactions in Nitrate Ester-based Explosives

    Science.gov (United States)

    Cawkwell, Marc; Kober, Ed; Myers, Thomas; Manner, Virginia

    2017-06-01

    In order to better understand and manipulate explosive sensitivity, we have prepared and analyzed a series of pentaerythritol tetranitrate-based explosives with systematic changes to the molecular structure. Reactive, extended Lagrangian Born-Oppenheimer molecular dynamics simulations have been performed on this series of molecules in the condensed phase to understand how the reactivity changes with the molecular modifications. The net reactions occurring over the first few hundred picoseconds under conditions of static high temperature and shock compression have been identified by an innovative analysis of coordination geometry changes and reaction types rather than attempting to detail each individual reaction. The evolution of temperature and pressure owing to evolving chemistry in the shock compressed materials were also captured accurately. Changes in exothermicity and the populations of intermediate and product moieties are connected to the systematic changes in stoichiometry. The results of the simulations are compared to preliminary estimates of sensitivity derived from small scale impact tests on materials synthesized recently at LANL.

  13. Intramolecular and Transannular Diels-Alder Reactions

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Ascic, Erhad

    2014-01-01

    Few reactions can compete with the Diels-Alder (DA) [4+2] cycloaddition for the rapid and efficient generation of molecular complexity. The DA reaction is atom-economic and stereospecific, as well as diastereo- and regioselective. The intramolecular version (IMDA) of the DA cycloaddition and its...

  14. Spallation reactions; Reactions de spallation

    Energy Technology Data Exchange (ETDEWEB)

    Cugon, J.

    1996-12-31

    Spallation reactions dominate the interactions of hadrons with nuclei in the GeV range (from {approx} 0.1 to {approx} 10 GeV). They correspond to a sometimes important ejection of light particles leaving most of the time a residue of mass commensurate with the target mass. The main features of the experimental data are briefly reviewed. The most successful theoretical model, namely the intranuclear cascade + evaporation model, is presented. Its physical content, results and possible improvements are critically discussed. Alternative approaches are shortly reviewed. (author). 84 refs.

  15. Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst

    Directory of Open Access Journals (Sweden)

    Zhaoyong Liu

    2015-01-01

    Full Text Available FCC (Fluid Catalytic Cracking catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst exceeds 8000 μg/g.

  16. Exploration of the Singlet O2 Oxidation of 8-Oxoguanine by Guided-Ion Beam Scattering and Density Functional Theory: Changes of Reaction Intermediates, Energetics, and Kinetics upon Protonation/Deprotonation and Hydration.

    Science.gov (United States)

    Sun, Yan; Lu, Wenchao; Liu, Jianbo

    2017-02-09

    8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is one of the most common DNA lesions resulting from reactive oxygen species and ionizing radiation, and is involved in mutagenesis, carcinogenesis, and cell death. Notably, 8-oxodGuo is more reactive toward singlet (a(1)Δg) O2 than the undamaged guanosine, and the lesions arising from the secondary oxidation of 8-oxodGuo are more mutagenic. Herein the (1)O2 oxidation of free base 8-oxoguanine (8-oxoG) was investigated at different initial conditions including protonated [8-oxoG + H](+), deprotonated [8-oxoG - H](-), and their monohydrates. Experiment was carried out on a guided-ion beam scattering tandem mass spectrometer. Measurements include the effects of collision energy (Ecol) on reaction cross sections over a center-of-mass Ecol range from 0.1 to 0.5 eV. The aim of this study is to quantitatively probe the sensitivity of the early stage of 8-oxoG oxidation to ionization and hydration. Density functional theory and Rice-Ramsperger-Kassel-Marcus calculations were performed to identify the intermediates and the products along reaction pathways and locate accessible reaction potential energy surfaces, and to rationalize reaction outcomes from energetic and kinetic points of view. No product was observed for the reaction of [8-oxoG + H](+)·W0,1 (W = H2O) because insurmountable barriers block the addition of (1)O2 to reactant ions. Neither was [8-oxoG - H](-) reactive with (1)O2, in this case due to the rapid decay of transient intermediates to starting reactants. However, the nonreactivity of [8-oxoG - H](-) was inverted by hydration; as a result, 4,5-dioxetane of [8-oxoG - H](-) was captured as the main oxidation product. Reaction cross section for [8-oxoG - H](-)·W + (1)O2 decreases with increasing Ecol and becomes negligible above 0.3 eV, indicating that the reaction is exothermic and has no barriers above reactants. The contrasting oxidation behaviors of [8-oxoG + H](+)·W0,1 and [8-oxoG - H](-)·W0,1, which

  17. Thin liquid films with time-dependent chemical reactions sheared by an ambient gas flow

    Science.gov (United States)

    Bender, Achim; Stephan, Peter; Gambaryan-Roisman, Tatiana

    2017-08-01

    Chemical reactions in thin liquid films are found in many industrial applications, e.g., in combustion chambers of internal combustion engines where a fuel film can develop on pistons or cylinder walls. The reactions within the film and the turbulent outer gas flow influence film stability and lead to film breakup, which in turn can lead to deposit formation. In this work we examine the evolution and stability of a thin liquid film in the presence of a first-order chemical reaction and under the influence of a turbulent gas flow. Long-wave theory with a double perturbation analysis is used to reduce the complexity of the problem and obtain an evolution equation for the film thickness. The chemical reaction is assumed to be slow compared to film evolution and the amount of reactant in the film is limited, which means that the reaction rate decreases with time as the reactant is consumed. A linear stability analysis is performed to identify the influence of reaction parameters, material properties, and environmental conditions on the film stability limits. Results indicate that exothermic reactions have a stabilizing effect whereas endothermic reactions destabilize the film and can lead to rupture. It is shown that an initially unstable film can become stable with time as the reaction rate decreases. The shearing of the film by the external gas flow leads to the appearance of traveling waves. The shear stress magnitude has a nonmonotonic influence on film stability.

  18. Influence of Impurities on High-Temperature Reactions of Kaolinite

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Sylvia M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division; Univ. of California, Berkeley, CA (United States); Pask, Joseph A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division; Univ. of California, Berkeley, CA (United States); Moya, Jose S. [Inst. of Ceramics and Glass, Arganda del Rey, Madrid (Spain)

    1982-01-01

    On heating kaolinite in DTA the second exothermic peak (~1275°C) is due to growth of mullite crystals accelerated by formation of a liquid phase. The third exothermic peak (~1460°C) is due to crystallization of cristobalite, Addition or presence of impurity oxides causes the second peak to shift in temperature, and accelerates the formation of cristobalite so that the third peak could appear as low as the second exothermic peak temperature.

  19. Electrospun manganese-cobalt oxide hollow nanofibres synthesized via combustion reactions and their lithium storage performance

    Science.gov (United States)

    Hwang, Soo Min; Kim, So Yeun; Kim, Jae-Geun; Kim, Ki Jae; Lee, Jong-Won; Park, Min-Sik; Kim, Young-Jun; Shahabuddin, Mohammed; Yamauchi, Yusuke; Kim, Jung Ho

    2015-04-01

    Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries.Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries. Electronic supplementary information (ESI) available: Experimental section; additional thermal analyses; XRD patterns; SEM and TEM results; N2 adsorption isotherms; differential capacity plots of galvanostatic voltage profiles and coulombic efficiency during cycling. See DOI: 10.1039/c5nr01145k

  20. GAS-PHASE SYNTHESIS OF PRECURSORS OF INTERSTELLAR GLYCINE: A COMPUTATIONAL STUDY OF THE REACTIONS OF ACETIC ACID WITH HYDROXYLAMINE AND ITS IONIZED AND PROTONATED DERIVATIVES

    Energy Technology Data Exchange (ETDEWEB)

    Barrientos, Carmen; Redondo, Pilar; Largo, Laura; Rayon, Victor M.; Largo, Antonio, E-mail: alargo@qf.uva.es [Departamento de Quimica Fisica y Quimica Inorganica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid (Spain)

    2012-04-01

    A computational study of the reactions of hydroxylamine and its ionized and protonated derivatives with acetic acid is provided. The reaction of neutral hydroxylamine with acetic acid, despite being clearly exothermic, involves a very large energy barrier. The reaction of ionized hydroxylamine with acetic acid is also clearly exothermic, but again a significant energy barrier is found (around 24 kcal mol{sup -1} at the CCSD(T) level). The reaction of the most stable protonated isomer of hydroxylamine, NH{sub 3}OH{sup +}, with acetic acid also involves a high barrier (more than 27 kcal mol{sup -1} at the CCSD(T) level). Only the higher energy isomer, NH{sub 2}OH{sup +}{sub 2}, leads to a sensibly lower energy barrier (about 2.3 kcal mol{sup -1} at the CCSD(T) level). Nevertheless, an estimate of the reaction coefficient at low temperatures such as those reigning in the interstellar medium gives very low values. Therefore, it seems that precursors of interstellar glycine could not be efficiently produced from the reactions of hydroxylamine-derived ions with acetic acid.

  1. In situ monitoring of the acetylene decomposition and gas temperature at reaction conditions for the deposition of carbon nanotubes using linear Raman scattering.

    Science.gov (United States)

    Reinhold-López, Karla; Braeuer, Andreas; Popovska, Nadejda; Leipertz, Alfred

    2010-08-16

    To understand the reaction mechanisms taking place by growing carbon nanotubes via the catalytic chemical vapor deposition process, a strategy to monitor in situ the gas phase at reaction conditions was developed applying linear Raman spectroscopy. The simultaneous determination of the gas temperature and composition was possible by a new strategy of the evaluation of the Raman spectra. In agreement to the well-known exothermic decomposition of acetylene, a gas temperature increase was quantified when acetylene was added to the incident flow. Information about exhaust gas recirculation and location of the maximal acetylene conversion was derived from the composition measurements.

  2. Ab initio molecular dynamics study of the Eley-Rideal reaction of H + Cl-Au(111) → HCl + Au(111): Impact of energy dissipation to surface phonons and electron-hole pairs.

    Science.gov (United States)

    Zhou, Linsen; Zhou, Xueyao; Alducin, Maite; Zhang, Liang; Jiang, Bin; Guo, Hua

    2018-01-07

    The reaction between an impinging H atom and a Cl atom adsorbed on Au(111), which is a prototype for the Eley-Rideal mechanism, is investigated using ab initio molecular dynamics at different incidence angles. The reaction yielding gaseous HCl with large internal excitation proceeds via both direct and hot-atom mechanisms. Significant energy exchange with both surface phonons and electron-hole pairs has been observed. However, their impact on the reactivity and final state distributions was found to be limited, thanks to the large exothermicity and small barrier of the reaction.

  3. Communication: Charge transfer dominates over proton transfer in the reaction of nitric acid with gas-phase hydrated electrons

    Science.gov (United States)

    Lengyel, Jozef; Med, Jakub; Slavíček, Petr; Beyer, Martin K.

    2017-09-01

    The reaction of HNO3 with hydrated electrons (H2O)n- (n = 35-65) in the gas phase was studied using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and ab initio molecular dynamics simulations. Kinetic analysis of the experimental data shows that OH-(H2O)m is formed primarily via a reaction of the hydrated electron with HNO3 inside the cluster, while proton transfer is not observed and NO3-(H2O)m is just a secondary product. The reaction enthalpy was determined using nanocalorimetry, revealing a quite exothermic charge transfer with -241 ± 69 kJ mol-1. Ab initio molecular dynamics simulations indicate that proton transfer is an allowed reaction pathway, but the overall thermochemistry favors charge transfer.

  4. Rapid establishment of polymerase chain reaction-restriction ...

    African Journals Online (AJOL)

    Seven sets of chloroplast primers could produce one or more distinct bands. After the amplified products were digested by 10 restriction enzymes, a total of 135 bands were detected, among which 98 bands (72.59%) were polymorphic. The cpDNA PCR-RFLP based genetic distance (GD) among 30 tea accessions ranged ...

  5. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    Energy Technology Data Exchange (ETDEWEB)

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  6. Implementation of the chemical PbLi/water reaction in the SIMMER code

    Energy Technology Data Exchange (ETDEWEB)

    Eboli, Marica, E-mail: marica.eboli@for.unipi.it [DICI—University of Pisa, Largo Lucio Lazzarino 2, 56122 Pisa (Italy); Forgione, Nicola [DICI—University of Pisa, Largo Lucio Lazzarino 2, 56122 Pisa (Italy); Del Nevo, Alessandro [ENEA FSN-ING-PAN, CR Brasimone, 40032 Camugnano, BO (Italy)

    2016-11-01

    Highlights: • Updated predictive capabilities of SIMMER-III code. • Verification of the implemented PbLi/Water chemical reactions. • Identification of code capabilities in modelling phenomena relevant to safety. • Validation against BLAST Test No. 5 experimental data successfully completed. • Need for new experimental campaign in support of code validation on LIFUS5/Mod3. - Abstract: The availability of a qualified system code for the deterministic safety analysis of the in-box LOCA postulated accident is of primary importance. Considering the renewed interest for the WCLL breeding blanket, such code shall be multi-phase, shall manage the thermodynamic interaction among the fluids, and shall include the exothermic chemical reaction between lithium-lead and water, generating oxides and hydrogen. The paper presents the implementation of the chemical correlations in SIMMER-III code, the verification of the code model in simple geometries and the first validation activity based on BLAST Test N°5 experimental data.

  7. Using simple donors to drive the equilibria of glycosyltransferase-catalyzed reactions.

    Science.gov (United States)

    Gantt, Richard W; Peltier-Pain, Pauline; Cournoyer, William J; Thorson, Jon S

    2011-08-21

    We report that simple glycoside donors can drastically shift the equilibria of glycosyltransferase-catalyzed reactions, transforming NDP-sugar formation from an endothermic to an exothermic process. To demonstrate the utility of this thermodynamic adaptability, we highlight the glycosyltransferase-catalyzed synthesis of 22 sugar nucleotides from simple aromatic sugar donors, as well as the corresponding in situ formation of sugar nucleotides as a driving force in the context of glycosyltransferase-catalyzed reactions for small-molecule glycodiversification. These simple aromatic donors also enabled a general colorimetric assay for glycosyltransfer, applicable to drug discovery, protein engineering and other fundamental sugar nucleotide-dependent investigations. This study directly challenges the general notion that NDP-sugars are 'high-energy' sugar donors when taken out of their traditional biological context.

  8. Thermophysicochemical Reaction of ZrCo-Hydrogen-Helium System

    Science.gov (United States)

    Jung, Kwangjin; Kang, Hee-Seok; Yun, Sei-Hun; Chung, Hongsuk

    2017-11-01

    Nuclear fusion energy, which is clean and infinite, has been studied for more than half a century. Efforts are in progress worldwide for the demonstration and validation of nuclear fusion energy. Korea has been developing hydrogen isotope storage and delivery system (SDS) technologies including a basic scientific study on a hydrogen storage medium. An SDS bed, which is a key component of the SDS, is used for storing hydrogen isotopes in a metal hydride form and supplying them to a tokamak. Thermophysicochemical properties of the ZrCo-H2-He system are investigated for the practical utilization of a hydriding alloy system. The hydriding reaction, in which ZrCoHx is composed as ZrCo absorbing hydrogen, is exothermic. The dehydriding reaction, in which ZrCoHx decomposes into ZrCo and hydrogen, is endothermic. The heat generated through the hydriding reaction interrupts the hydriding progress. The heat loss by a dehydriding reaction impedes the dehydriding progress. The tritium decay product, helium-3, covers the ZrCo and keeps the hydrogen from contact with ZrCo in the SDS bed. In this study, we designed and fabricated a ZrCo bed and its performance test rig. The helium blanketing effect on a ZrCo hydrogen reaction with 0 % to 20 % helium content in a gaseous phase and a helium blanket removal method were studied experimentally. In addition, the volumetric flow rates and temperature at the beginning of a ZrCo hydrogen reaction in a hydrogen or helium atmosphere, and the cooling of the SDS bed by radiation only and by both radiation and natural convection related to the reuse cycle, were obtained.

  9. Agile Science Planning: Rapid Response Re-planning Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop autonomous rapid response to science observations in missions targeting small bodies in fly-by mode where observing and reaction time is precious.

  10. Spot Feeding Spheroidal Graphite Iron with Exothermic and Insulating Ram-Up Sleeves in Vertically Parted Moulds: Efficiency, Microstructure, Dimensional Accuracy, Deformation, and Driving Force and Feeding Criteria Identification

    DEFF Research Database (Denmark)

    Vedel-Smith, Nikolaj Kjelgaard

    the castings, as well as the exothermic and insulating feeders. The thermal deformation related to the feeder combinations are investigated, and it is found that the thermal gradients created by the feeders could be signified by the deformation of the plane reverse side of the casting. The eutectoid phase...... in this dissertation is based on large-scale quantitative experiments with duplicates for statistical representation. The focus, as stated by the dissertation title, has been: ‘Spot Feeding Spherical Graphite Iron with Exothermicand Insulating Ram-Up Sleeves in Vertically Parted Moulds’. The application of spot...... feeders (ram-up sleeves) is investigated, showing that this new feeding approach can be used successfully to feed secluded sections inductile cast iron (EN-GJS-500-7). The feeder efficiency is tested using a high Silicon (Si) ductile iron (EN-GJS-450-10). The limits for the examined feeder configurations...

  11. Gas-phase thermolysis reaction of formaldehyde diperoxide. Kinetic study and theoretical mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Jorge, Nelly Lidia [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Av. Las Palmeras 4, 18100 Armilla, Granada (Spain); Area de Quimica Fisica Facultad de Ciencias Exactas y Naturales y Agrimensura, UNNE, Avda. Libertad 5460, 3400 Corrientes (Argentina); Romero, Jorge Marcelo [Area de Quimica Fisica Facultad de Ciencias Exactas y Naturales y Agrimensura, UNNE, Avda. Libertad 5460, 3400 Corrientes (Argentina); Grand, Andre [INAC, SCIB, Laboratoire ' Lesions des Acides Nucleiques' , UMR CEA-UJF E3, CEA-Grenoble, 17 Rue des Martyrs, 38054 Grenoble cedex 9 (France); Hernandez-Laguna, Alfonso, E-mail: ahlaguna@ugr.es [Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Av. Las Palmeras 4, 18100 Armilla, Granada (Spain)

    2012-01-17

    Highlights: Black-Right-Pointing-Pointer Kinetic and mechanism of the gas-phase thermolysis of tetroxane were determined. Black-Right-Pointing-Pointer Gas chromatography and computational potential energy surfaces were performed. Black-Right-Pointing-Pointer A mechanism in steps looked like the most probable mechanism. Black-Right-Pointing-Pointer A spin-orbit coupling appeared at the singlet and triple diradical open structures. Black-Right-Pointing-Pointer A non-adiabatic crossing from the singlet to the triplet state occurred. - Abstract: Gas-phase thermolysis reaction of formaldehyde diperoxide (1,2,4,5-tetroxane) was performed in an injection chamber of a gas chromatograph at a range of 463-503 K. The average Arrhenius activation energy and pre-exponential factor were 29.3 {+-} 0.8 kcal/mol and 5.2 Multiplication-Sign 10{sup 13} s{sup -1}, respectively. Critical points and reaction paths of the ground singlet and first triplet potential energy surfaces (PES) were calculated, using DFT method at BHANDHLYP/6-311+G{sup Asterisk-Operator Asterisk-Operator} level of the theory. Also, G3 calculations were performed on the reactant and products. Reaction by the ground-singlet and first-triplet states turned out to be endothermic and exothermic, respectively. The mechanism in three steps seemed to be the most probable one. An electronically non-adiabatic process appeared, in which a crossing, at an open diradical structure, from the singlet to the triplet state PES occurred, due to a spin-orbit coupling, yielding an exothermic reaction. Theoretical kinetic constant coming from the non- adiabatic transition from the singlet to the triplet state agrees with the experimental values.

  12. Enthalpies of the reaction of N-methylpyrrolidone with C/sub 9/-C/sub 12/ arenes

    Energy Technology Data Exchange (ETDEWEB)

    Yanbukhtina, R.A.; Gaile, A.A.; Semenov, L.V.

    1988-07-20

    Mixing of N-methylpyrrolidone with monocycloaromatic hydrocarbons takes place with an endothermic effect and mixing with bicycloaromatic hydrocarbons occurs with an exothermic effect. This is due to an increase in the proportion of the specific reaction in going from systems with mono- and bicycloaromatic hydrocarbons from 30 to 50-60% of the total enthalpy of the reaction. The enthalpies of the specific reaction of arenes with N-methylpyrrolidone are correlated with the donor numbers of the hydrocarbons. The difference in the enthalpies of solvation of saturated and aromatic hydrocarbons by N-methylpyrrolidone is greater than with dimethylformamide and furfural, which is in agreement with the higher selectivity of N-methylpyrrolidone.

  13. Rapid Development: A Content Analysis Comparison of Literature and Purposive Sampling of AFRL Rapid Reaction Projects

    Science.gov (United States)

    2011-12-01

    warning for incoming German bombers (Brown, 1999). The Culin Hedgerow Cutter was adapted from steel obstacles (originally emplaced by the German army...and attached to the front of Sherman tanks allowing the breaching of hedgerows to counter German emplacements in confined fields in the taking of the...Government Accounting Office. DoD Acquisitions: Assessments of Selected Weapons Programs. Washington: GPO, 30 March 2010 Guttman, Jon, “French Hedgerows

  14. Rapid Prototyping Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The ARDEC Rapid Prototyping (RP) Laboratory was established in December 1992 to provide low cost RP capabilities to the ARDEC engineering community. The Stratasys,...

  15. Multistage reaction pathways in detonating high explosives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ying [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kalia, Rajiv K.; Nakano, Aiichiro; Nomura, Ken-ichi; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2014-11-17

    Atomistic mechanisms underlying the reaction time and intermediate reaction products of detonating high explosives far from equilibrium have been elusive. This is because detonation is one of the hardest multiscale physics problems, in which diverse length and time scales play important roles. Here, large spatiotemporal-scale reactive molecular dynamics simulations validated by quantum molecular dynamics simulations reveal a two-stage reaction mechanism during the detonation of cyclotrimethylenetrinitramine crystal. Rapid production of N{sub 2} and H{sub 2}O within ∼10 ps is followed by delayed production of CO molecules beyond ns. We found that further decomposition towards the final products is inhibited by the formation of large metastable carbon- and oxygen-rich clusters with fractal geometry. In addition, we found distinct unimolecular and intermolecular reaction pathways, respectively, for the rapid N{sub 2} and H{sub 2}O productions.

  16. Rebinding in biochemical reactions on membranes

    Science.gov (United States)

    Lawley, Sean D.; Keener, James P.

    2017-10-01

    The behavior of many biochemical processes depends crucially on molecules rapidly rebinding after dissociating. In the case of multisite protein modification, the importance of rebinding has been demonstrated both experimentally and through several recent computational studies involving stochastic spatial simulations. As rebinding stems from spatio-temporal correlations, theorists have resorted to models that explicitly include space to properly account for the effects of rebinding. However, for reactions in three space dimensions it was recently shown that well-mixed ordinary differential equation (ODE) models can incorporate rebinding by adding connections to the reaction network. The rate constants for these new connections involve the probability that a pair of molecules rapidly rebinds after dissociation. In order to study biochemical reactions on membranes, in this paper we derive an explicit formula for this rebinding probability for reactions in two space dimensions. We show that ODE models can use the formula to replicate detailed stochastic spatial simulations, and that the formula can predict ultrasensitivity for reactions involving multisite modification of membrane-bound proteins. Further, we compute a new concentration-dependent rebinding probability for reactions in three space dimensions. Our analysis predicts that rebinding plays a much larger role in reactions on membranes compared to reactions in cytoplasm.

  17. Anaphylaxis-Like Reactions

    Science.gov (United States)

    ... Home Conditions Anaphylaxis Anaphylaxis-Like Reactions Anaphylaxis-Like Reactions Make an Appointment Refer a Patient Ask a ... exposed to a foreign substance, some people suffer reactions identical to anaphylaxis, but no allergy (IgE antibody) ...

  18. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  19. Rapid heating of matter using high power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Woosuk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-08

    This slide presentation describes motivation (uniform and rapid heating of a target, opportunity to study warm dense matter, study of nuclear fusion reactions), rapid heating of matter with intense laser-driven ion beams, visualization of the expanding warm dense gold and diamond, and nuclear fusion experiments using high power lasers (direct heating of deuterium spheres (radius ~ 10nm) with an intense laser pulse.

  20. Catalytic Friedel-Crafts reaction of aminocyclopropanes.

    Science.gov (United States)

    de Nanteuil, Florian; Loup, Joachim; Waser, Jérôme

    2013-07-19

    A Lewis acid catalyzed Friedel-Crafts reaction between donor-acceptor aminocyclopropanes and indoles and other electron-rich aromatic compounds is reported. Indole alkylation at the C3 position was generally obtained for a broad range of functional groups and substitution patterns. In the case of C3-substituted indoles, C2 alkylation was observed. The reaction gives a rapid access to gamma amino acid derivatives present in numerous bioactive molecules.

  1. On Thermonuclear Reaction Rates

    OpenAIRE

    Haubold, H. J.; Mathai, A. M.

    1996-01-01

    Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the cases of nonresonant, modified nonresonant, screened nonresonant and resonant cases are given. These are expressed in terms of H-functions, G-functions and in computable series forms. Computational aspects are als...

  2. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  3. Self-triggering reaction kinetics between nitrates and aluminium powder

    Energy Technology Data Exchange (ETDEWEB)

    Demichela, Micaela [SAfeR-Centro Studi su Sicurezza Affidabilita e Rischi, Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi, 24, I 10129 Torino (Italy)], E-mail: micaela.demichela@polito.it

    2007-09-05

    During the night between the 19 and 20 September 2003, a loud explosion occurred at about 3 km from the town of Carignano that was clearly heard at a distance of some tens of kilometres. The explosion almost completely destroyed most of the laboratories of the Panzera Company that were used for the production of fireworks. The results of the research activities that were carried out using a differential scanning calorimeter (DSC) on the same raw materials that made up the pyrotechnical mixture that exploded are reported in this paper. This activity was carried out to identify the dynamics of the accident. It proved possible to verify how the event was produced because of a slow exothermic reaction which, after about 8 h, caused the self-triggering of 120 kg of finished product. The detonation can therefore be put down to a runaway reaction in the solid phase, whose primogenial causes can be attributed to a still craftsman type production system, not conformed to the rigorous controls and inspections as those required by a safety management system for major risk plants, as the Panzera Company was.

  4. Modeling of Sheath Ion-Molecule Reactions in Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes

    Science.gov (United States)

    Hash, David B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    In many plasma simulations, ion-molecule reactions are modeled using ion energy independent reaction rate coefficients that are taken from low temperature selected-ion flow tube experiments. Only exothermic or nearly thermoneutral reactions are considered. This is appropriate for plasma applications such as high-density plasma sources in which sheaths are collisionless and ion temperatures 111 the bulk p!asma do not deviate significantly from the gas temperature. However, for applications at high pressure and large sheath voltages, this assumption does not hold as the sheaths are collisional and ions gain significant energy in the sheaths from Joule heating. Ion temperatures and thus reaction rates vary significantly across the discharge, and endothermic reactions become important in the sheaths. One such application is plasma enhanced chemical vapor deposition of carbon nanotubes in which dc discharges are struck at pressures between 1-20 Torr with applied voltages in the range of 500-700 V. The present work investigates The importance of the inclusion of ion energy dependent ion-molecule reaction rates and the role of collision induced dissociation in generating radicals from the feedstock used in carbon nanotube growth.

  5. Analysis of self-propagating intermetallic reaction in nanoscale multilayers of binary metals

    Science.gov (United States)

    Kim, Kyoungjin

    2017-03-01

    Nanoscale multilayers of two different metals could exhibit super-fast intermetallic reaction wave that accompanies high level of exothermic heat release, while additional advantage is a very small ignition delay. They could be a promising candidate for the core technology in realizing micron-sized initiation device for explosives detonation or propellants ignition in various defense and civilian applications. This numerical investigation focuses on the numerical modeling and computations of the ignition and self-propagating reaction behaviors in nanoscale intermetallic multilayer structures made of alternating binary metal layers of boron and titanium. Due to thin film nature of metallic multilayers, intermetallic reaction propagation across the repeating bimetallic multilayers is approximated to the one-dimensional transient model of thermal diffusion and atomic species diffusion, and the intermetallic reaction between two metal species is assumed to follow Arrhenius dependence on temperature. The computational results show the details of ignition and propagation characteristics of intermetallic reaction wave by evaluating and discussing the effects of key parameters, such as multilayer thickness, excess of one metal species, and presence of atomic premixing at interface of boron and titanium layers, on ignition delay and propagation speed of self-sustaining reaction wave.

  6. Rapid Airplane Parametric Input Design (RAPID)

    Science.gov (United States)

    Smith, Robert E.

    1995-01-01

    RAPID is a methodology and software system to define a class of airplane configurations and directly evaluate surface grids, volume grids, and grid sensitivity on and about the configurations. A distinguishing characteristic which separates RAPID from other airplane surface modellers is that the output grids and grid sensitivity are directly applicable in CFD analysis. A small set of design parameters and grid control parameters govern the process which is incorporated into interactive software for 'real time' visual analysis and into batch software for the application of optimization technology. The computed surface grids and volume grids are suitable for a wide range of Computational Fluid Dynamics (CFD) simulation. The general airplane configuration has wing, fuselage, horizontal tail, and vertical tail components. The double-delta wing and tail components are manifested by solving a fourth order partial differential equation (PDE) subject to Dirichlet and Neumann boundary conditions. The design parameters are incorporated into the boundary conditions and therefore govern the shapes of the surfaces. The PDE solution yields a smooth transition between boundaries. Surface grids suitable for CFD calculation are created by establishing an H-type topology about the configuration and incorporating grid spacing functions in the PDE equation for the lifting components and the fuselage definition equations. User specified grid parameters govern the location and degree of grid concentration. A two-block volume grid about a configuration is calculated using the Control Point Form (CPF) technique. The interactive software, which runs on Silicon Graphics IRIS workstations, allows design parameters to be continuously varied and the resulting surface grid to be observed in real time. The batch software computes both the surface and volume grids and also computes the sensitivity of the output grid with respect to the input design parameters by applying the precompiler tool

  7. Rapidly Developing Toxic Epidermal Necrolysis

    Directory of Open Access Journals (Sweden)

    Viktoria Oline Barrios Poulsen

    2013-01-01

    Full Text Available Severe cutaneous reactions with potentially fatal outcomes can have many different causes. The Stevens-Johnson syndrome (SJS and toxic epidermal necrolysis (TEN are rare. They are characterized by a low incidence but high mortality, and drugs are most commonly implicated. Urgent active therapy is required. Prompt recognition and withdrawal of suspect drug and rapid intervention can result in favourable outcome. No further international guidelines for treatment exist, and much of the treatment relies on old or experimental concepts with no scientific evidence. We report on a 54-year-old man experiencing rapidly developing drug-induced severe TEN and presented multiorgan failure involving the respiratory and circulatory system, coagulopathy, and renal insufficiency. Detachment counted 30% of total body surface area (TBSA. SCORTEN = 5, indicating a mortality rate >90%. The patient was sedated and mechanically ventilated, supported with fluids and inotropes to maintain a stable circulation. Component therapy was guided by thromboelastography (TEG. The patient received plasmapheresis, and shock reversal treatment was initiated. He was transferred to a specialized intensive care burn unit within 24 hours from admittance. The initial care was continued, and hemodialysis was started. Pulmonary, circulatory, and renal sequelae resolved with intensive care, and re-epithelialization progressed slowly. The patient was discharged home on hospital day 19.

  8. Rapid shallow breathing

    Science.gov (United States)

    ... the smallest air passages of the lungs in children ( bronchiolitis ) Pneumonia or other lung infection Transient tachypnea of the newborn Anxiety and panic Other serious lung disease Home Care Rapid, shallow breathing should not be treated at home. It is ...

  9. Rapid Strep Test

    Science.gov (United States)

    ... worse than normal. Your first thoughts turn to strep throat. A rapid strep test in your doctor’s office ... your suspicions.Viruses cause most sore throats. However, strep throat is an infection caused by the Group A ...

  10. RAPID3? Aptly named!

    Science.gov (United States)

    Berthelot, J-M

    2014-01-01

    The RAPID3 score is the sum of three 0-10 patient self-report scores: pain, functional impairment on MDHAQ, and patient global estimate. It requires 5 seconds for scoring and can be used in all rheumatologic conditions, although it has mostly been used in rheumatoid arthritis where cutoffs for low disease activity (12/30) have been set. A RAPID3 score of ≤ 3/30 with 1 or 0 swollen joints (RAPID3 ≤ 3 + ≤ SJ1) provides remission criteria comparable to Boolean, SDAI, CDAI, and DAS28 remission criteria, in far less time than a formal joint count. RAPID3 performs as well as the DAS28 in separating active drugs from placebos in clinical trials. RAPID3 also predicts subsequent structural disease progression. RAPID3 can be determined at short intervals at home, allowing the determination of the area under the curve of disease activity between two visits and flare detection. However, RAPID3 should not be seen as a substitute for DAS28 and face to face visits in routine care. Monitoring patient status with only self-report information without a rheumatologist's advice (including joints and physical examination, and consideration of imaging and laboratory tests) may indeed be as undesirable for most patients than joint examination without a patient questionnaire. Conversely, combining the RAPID3 and the DAS28 may consist in faster or more sensitive confirmation that a medication is effective. Similarly, better enquiring of most important concerns of patients (pain, functional status and overall opinion on their disorder) should reinforces patients' confidence in their rheumatologist and treatments.

  11. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Use of Isotopes for Studying Reaction Mechanisms Distinguishing between Single Minima and Rapidly Equilibrating Structures. Uday Maitra J Chandrasekhar. Series Article Volume 2 Issue 10 October 1997 pp 29-37 ...

  12. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Use of Isotopes for Studying Reaction Mechanisms - Distinguishing between Single Mimima and Rapidly Equilibrating Structures. Uday Maitra J Chandrasekhar. Volume 16 Issue 12 December 2011 pp 1315-1323 ...

  13. Reaction mechanism for the free-edge oxidation of soot by O 2

    KAUST Repository

    Raj, Abhijeet

    2012-11-01

    The reaction pathways for the oxidation by O 2 of polycyclic aromatic hydrocarbons present in soot particles are investigated using density functional theory at B3LYP/6-311++G(d,p) level of theory. For this, pyrene radical (4-pyrenyl) is chosen as the model molecule, as most soot models present in the literature employ the reactions involving the conversion of 4-pyrenyl to 4-phenanthryl by O 2 and OH to account for soot oxidation. Several routes for the formation of CO and CO 2 are proposed. The addition of O 2 on a radical site to form a peroxyl radical is found to be barrierless and exothermic with reaction energy of 188kJ/mol. For the oxidation reaction to proceed further, three pathways are suggested, each of which involve the activation energies of 104, 167 and 115kJ/mol relative to the peroxyl radical. The effect of the presence of H atom on a carbon atom neighboring the radical site on the energetics of carbon oxidation is assessed. Those intermediate species formed during oxidation with seven-membered rings or with a phenolic group are found to be highly stable. The rate constants evaluated using transition state theory in the temperature range of 300-3000K for the reactions involved in the mechanism are provided. © 2012 The Combustion Institute.

  14. Experimental Study on Reaction Characteristics of PTFE/Ti/W Energetic Materials under Explosive Loading

    Directory of Open Access Journals (Sweden)

    Yan Li

    2016-11-01

    Full Text Available Metal/fluoropolymer composites represent a new category of energetic structural materials that release energy through exothermic chemical reactions initiated under shock loading conditions. This paper describes an experiment designed to study the reaction characteristics of energetic materials with low porosity under explosive loading. Three PTFE (polytetrafluoroethylene/Ti/W mixtures with different W contents are processed through pressing and sintering. An inert PTFE/W mixture without reactive Ti particles is also prepared to serve as a reference. Shock-induced chemical reactions are recorded by high-speed video through a narrow observation window. Related shock parameters are calculated based on experimental data, and differences in energy release are discussed. The results show that the reaction propagation of PTFE/Ti/W energetic materials with low porosity under explosive loading is not self-sustained. As propagation distance increases, the energy release gradually decreases. In addition, reaction failure distance in PTFE/Ti/W composites is inversely proportional to the W content. Porosity increased the failure distance due to higher shock temperature.

  15. A theoretical study of the mechanism of the addition reaction between carbene and azacyclopropane

    Directory of Open Access Journals (Sweden)

    XIAOJUN TAN

    2010-05-01

    Full Text Available The mechanism of the addition reaction between carbene and azacyclopropane was investigated using the second-order Moller–Plesset perturbation theory (MP2. By using the 6-311+G* basis set, geometry optimization, vibrational analysis and the energy properties of the involved stationary points on the potential energy surface were calculated. From the surface energy profile, it can be predicted that there are two reaction mechanisms. The first one (1 is carbene attack at the N atom of azacyclopropane to form an intermediate, 1a (IM1a, which is a barrier-free exothermic reaction. Then, IM1a can isomerize to IM1b via a transition state 1a (TS1a, in which the potential barrier is 30.0 kJ/mol. Subsequently, IM1b isomerizes to a product (Pro1 via TS1b with a potential barrier of 39.3 kJ/mol. The other one (2 is carbene attack at the C atom of azacyclopropane, firstly to form IM2 via TS2a, the potential barrier is 35.4 kJ/mol. Then IM2 isomerizes to a product (Pro2 via TS2b with a potential barrier of 35.1 kJ/mol. Correspondingly, the reaction energy for the reactions (1 and (2 is –478.3 and –509.9 kJ/mol, respectively. Additionally, the orbital interactions are also discussed for the leading intermediate.

  16. Polyjet technology applications for rapid tooling

    Directory of Open Access Journals (Sweden)

    Udroiu Razvan

    2017-01-01

    Full Text Available Polymer Jetting (PolyJet has proved to be one of the most accurate additive manufacturing technologies, in order to manufacture rapid tools. Rapid Tooling (RT is different from conventional tooling as follow: manufacturing time is shorter, the cost is much less, but the tool life is shorter and tolerances are wider. The purpose of this paper is to make a comparative study between the soft tools (silicon moulds and hard tools (acrylic thermoplastic moulds based on the Polymer Jetting technology. Thus, two types of moulds have been made in order to manufacture a test part. Reaction injection moulding (RIM and casting techniques were used to fill these moulds with resins that simulate the plastic injection materials. Rapid tooling applications, such as indirect tooling and direct tooling, based on PolyJet technology were experimentally investigated.

  17. Reaction between CH2 and HCCN: a theoretical approach to acrylonitrile formation in the interstellar medium.

    Science.gov (United States)

    Shivani; Misra, Alka; Tandon, Poonam

    2014-04-01

    Acrylonitrile (CH2CHCN) was first detected in dense molecular cloud SgrB2. The synthesis of this interstellar molecule is reported to be quite difficult. Therefore, in the present work an attempt has been made to explore the possibility of formation of acrylonitrile from some simple molecules and radicals detected in interstellar space by radical-radical interaction scheme, both in the gas phase and in the icy grains. All calculations are performed using quantum chemical methods with density functional theory (DFT) at the B3LYP/6-311G (d,p) level and Møller-Plesset perturbation theory at the MP2/6-311G (d,p) level. In the discussed chemical pathway, the reaction is found to be totally exothermic and barrier less giving rise to a high probability of acrylonitrile formation in Interstellar space.

  18. Hall Effects on Unsteady MHD Reactive Flow Through a Porous Channel with Convective Heating at the Arrhenius Reaction Rate

    Science.gov (United States)

    Das, S.; Patra, R. R.; Jana, R. N.; Makinde, O. D.

    2017-09-01

    This paper deals with the study of an unsteady magnetohydrodynamic (MHD) flow and heat transfer of a reactive, viscous, incompressible, electrically conducting fluid between two infinitely long parallel porous plates where one of the plates is set into impulsive/uniformly accelerated motion in the presence of a uniform transverse magnetic field at the Arrhenius reaction rate, with the Hall currents taken into account. The transient momentum equations are solved analytically with the use of the Laplace transform technique, and the velocity field and shear stresses are obtained in a unified closed form. The energy equation is tackled numerically using Matlab. The effects of the pertinent parameters on the fluid velocity, temperature, shear stresses, and the heat transfer rate at the plates are investigated. The results reveal that the combined effects of magnetic field, suction/injection, exothermic reaction, and variable thermal conductivity have a significant impact on the hydromagnetic flow and heat transfer.

  19. [Adverse reactions to insulin].

    Science.gov (United States)

    Liñana, J J; Montoro, F J; Hernández, M D; Basomba, A

    1997-07-01

    The prevalence of allergic reactions to insuline has decreased during the last few years. Probably this is due to the use of the newly-developed recombinant human insuline. At present, adverse reactions to insuline occur in 5-10% of patients on therapy with insuline. Adverse reactions may be local (more frequent) or systemic (rare). Insuline resistance consists in a different type of immunological reaction. Diagnosis of allergy to insuline is based on clinical history and cutaneous and serological tests. Treatment depends upon the severity of the reaction. When insuline is indispensable despite a previous allergic reaction, a desensitization protocol may be implemented.

  20. Rapid small lot manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Harrigan, R.W.

    1998-05-09

    The direct connection of information, captured in forms such as CAD databases, to the factory floor is enabling a revolution in manufacturing. Rapid response to very dynamic market conditions is becoming the norm rather than the exception. In order to provide economical rapid fabrication of small numbers of variable products, one must design with manufacturing constraints in mind. In addition, flexible manufacturing systems must be programmed automatically to reduce the time for product change over in the factory and eliminate human errors. Sensor based machine control is needed to adapt idealized, model based machine programs to uncontrolled variables such as the condition of raw materials and fabrication tolerances.

  1. Combustion Synthesis of UHTC Composites from Ti–B4C Solid State Reaction with Addition of VIb Transition Metals

    Directory of Open Access Journals (Sweden)

    Chun-Liang Yeh

    2017-06-01

    Full Text Available UHTC composites were prepared by self-propagating high-temperature synthesis (SHS from the Ti–B4C reaction system with addition of Cr, Mo, and W. The starting sample composition was formulated as (3−xTi + B4C + xMe with x = 0.1–1.0 and Me = Cr, Mo, or W. For all samples conducted in this study, self-sustaining combustion was well established and propagated with a distinct reaction front. With no addition of Cr, Mo, or W, solid state combustion of the 3Ti + B4C sample featuring a combustion front temperature (Tc of 1766 °C and a combustion wave velocity (Vf of 16.5 mm/s was highly exothermic and produced an in situ composite of 2TiB2 + TiC. When Cr, Mo, or W was adopted to replace a portion of Ti, the reaction exothermicity was lowered, and hence, a significant decrease in Tc (from 1720 to 1390 °C and Vf (from 16.1 to 3.9 mm/s was observed. With addition of Cr, Mo, and W, the final products were CrB-, MoB-, and WB-added TiB2–TiC composites. The absence of CrB2, MoB2, and WB2 was attributed partly to the loss of boron from thermal decomposition of B4C and partly to lack of sufficient reaction time inherent to the SHS process.

  2. Oxygen radical-mediated oxidation reactions of an alanine peptide motif - density functional theory and transition state theory study.

    Science.gov (United States)

    Chen, Hsing-Yu; Jang, Soonmin; Jinn, Tzyy-Rong; Chang, Jia-Yaw; Lu, Hsiu-Feng; Li, Feng-Yin

    2012-04-24

    Oxygen-base (O-base) oxidation in protein backbone is important in the protein backbone fragmentation due to the attack from reactive oxygen species (ROS). In this study, an alanine peptide was used model system to investigate this O-base oxidation by employing density functional theory (DFT) calculations combining with continuum solvent model. Detailed reaction steps were analyzed along with their reaction rate constants. Most of the O-base oxidation reactions for this alanine peptide are exothermic except for the bond-breakage of the Cα-N bond to form hydroperoxy alanine radical. Among the reactions investigated in this study, the activated energy of OH α-H abstraction is the lowest one, while the generation of alkylperoxy peptide radical must overcome the highest energy barrier. The aqueous situation facilitates the oxidation reactions to generate hydroxyl alanine peptide derivatives except for the fragmentations of alkoxyl alanine peptide radical. The Cα-Cβ bond of the alkoxyl alanine peptide radical is more labile than the peptide bond. the rate-determining step of oxidation in protein backbone is the generation of hydroperoxy peptide radical via the reaction of alkylperoxy peptide radical with HO2. The stabilities of alkylperoxy peptide radical and complex of alkylperoxy peptide radical with HO2 are crucial in this O-base oxidation reaction.

  3. Oxygen radical-mediated oxidation reactions of an alanine peptide motif - density functional theory and transition state theory study

    Directory of Open Access Journals (Sweden)

    Chen Hsing-Yu

    2012-04-01

    Full Text Available Abstract Background Oxygen-base (O-base oxidation in protein backbone is important in the protein backbone fragmentation due to the attack from reactive oxygen species (ROS. In this study, an alanine peptide was used model system to investigate this O-base oxidation by employing density functional theory (DFT calculations combining with continuum solvent model. Detailed reaction steps were analyzed along with their reaction rate constants. Results Most of the O-base oxidation reactions for this alanine peptide are exothermic except for the bond-breakage of the Cα-N bond to form hydroperoxy alanine radical. Among the reactions investigated in this study, the activated energy of OH α-H abstraction is the lowest one, while the generation of alkylperoxy peptide radical must overcome the highest energy barrier. The aqueous situation facilitates the oxidation reactions to generate hydroxyl alanine peptide derivatives except for the fragmentations of alkoxyl alanine peptide radical. The Cα-Cβ bond of the alkoxyl alanine peptide radical is more labile than the peptide bond. Conclusion the rate-determining step of oxidation in protein backbone is the generation of hydroperoxy peptide radical via the reaction of alkylperoxy peptide radical with HO2. The stabilities of alkylperoxy peptide radical and complex of alkylperoxy peptide radical with HO2 are crucial in this O-base oxidation reaction.

  4. Allergic reactions (image)

    Science.gov (United States)

    Allergic reaction can be provoked by skin contact with poison plants, chemicals and animal scratches, as well as ... mildew, dust, nuts and shellfish, may also cause allergic reaction. Medications such as penicillin and other antibiotics are ...

  5. Cosmetic tattoo pigment reaction

    National Research Council Canada - National Science Library

    Greywal, Tanya; Cohen, Philip R

    2016-01-01

    BackgroundCutaneous reactions to tattoos are most commonly granulomatous or lichenoid.PurposeWe describe a woman who developed a lymphocytic reaction following a cosmetic tattoo procedure with black dye...

  6. Rapid Cycling and Its Treatment

    Science.gov (United States)

    ... Announcements Public Service Announcements Partnering with DBSA Rapid Cycling and its Treatment What is bipolar disorder? Bipolar ... to Depression and Manic Depression . What is rapid cycling? Rapid cycling is defined as four or more ...

  7. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  8. The Atmospherically Important Reaction of Hydroxyl Radicals with Methyl Nitrate: A Theoretical Study Involving the Calculation of Reaction Mechanisms, Enthalpies, Activation Energies, and Rate Coefficients.

    Science.gov (United States)

    Ng, Maggie; Mok, Daniel K W; Lee, Edmond P F; Dyke, John M

    2017-09-07

    A theoretical study, involving the calculation of reaction enthalpies, activation energies, mechanisms, and rate coefficients, was made of the reaction of hydroxyl radicals with methyl nitrate, an important process for methyl nitrate removal in the earth's atmosphere. Four reaction channels were considered: formation of H 2 O + CH 2 ONO 2 , CH 3 OOH + NO 2 , CH 3 OH + NO 3 , and CH 3 O + HNO 3 . For all channels, geometry optimization and frequency calculations were performed at the M06-2X/6-31+G** level, while relative energies were improved at the UCCSD(T*)-F12/CBS level. The major channel is found to be the H abstraction channel, to give the products H 2 O + CH 2 ONO 2 . The reaction enthalpy (ΔH 298 K RX ) of this channel is computed as -17.90 kcal mol -1 . Although the other reaction channels are also exothermic, their reaction barriers are high (>24 kcal mol -1 ), and therefore these reactions do not contribute to the overall rate coefficient in the temperature range considered (200-400 K). Pathways via three transition states were identified for the H abstraction channel. Rate coefficients were calculated for these pathways at various levels of variational transition state theory including tunneling. The results obtained are used to distinguish between two sets of experimental rate coefficients, measured in the temperature range of 200-400 K, one of which is approximately an order of magnitude greater than the other. This comparison, as well as the temperature dependence of the computed rate coefficients, shows that the lower experimental values are favored. The implications of the results to atmospheric chemistry are discussed.

  9. Reaction Time (Polish language)

    OpenAIRE

    Iermakov, Sergii

    2014-01-01

    Reaction time is the interval time between the presentation of a stimulus and the initiation of the muscular response to that stimulus.If there is only one possible response (simple reaction time) it will only take a short time to react. If there are several possible responses (choice reaction time) then it will take longer to determine which response to carry out.

  10. Laser enhanced chemical reactions

    Science.gov (United States)

    Included is the discussion of infrared diode lasers used to study time dependent dynamic events. Also, hot atom excitation of vibrational states of polyatomic molecules, bimolecular quenching and reactions of O(sup 1)D, bimolecular reaction studies of the OH + CO yields H + CO2 system, and the chemical dynamics of the reaction between chlorine atoms and deuterated cyclohexane are covered briefly.

  11. (MIRC) reaction w

    Indian Academy of Sciences (India)

    Sudesh Kumari

    as eco-friendly reaction media in catalyst free organic synthesis.7 Ethylene glycol has promising physical ... these properties it is used as a promising green media in many catalysed/ uncatalysed organic reactions ..... Ruijter E, Scheffelaar R and Orru R V A 2011 Multi- component Reaction Design in the Quest for Molecular ...

  12. SUPPLEMENTARY INFORMATION RAPID COMMUNICATION ...

    Indian Academy of Sciences (India)

    Sulfated polyborate: A mild, efficient catalyst for synthesis of N-tert- butyl/N-trityl protected amides via Ritter reaction. KRISHNA S INDALKAR, CHETAN K KHATRI and GANESH U CHATURBHUJ*. Department of Pharmaceutical Sciences and Technology, Institute of Chemical Technology, Mumbai, Maharashtra 400 019 ...

  13. Rapid manufacturing for microfluidics

    CSIR Research Space (South Africa)

    Land, K

    2012-10-01

    Full Text Available . Microfluidics is at the forefront of developing solutions for drug discovery, diagnostics (from glucose tests to malaria and TB testing) and environmental diagnostics (E-coli monitoring of drinking water). In order to quickly implement new designs, a rapid...

  14. Rapid Prototyping in PVS

    Science.gov (United States)

    Munoz, Cesar A.; Butler, Ricky (Technical Monitor)

    2003-01-01

    PVSio is a conservative extension to the PVS prelude library that provides basic input/output capabilities to the PVS ground evaluator. It supports rapid prototyping in PVS by enhancing the specification language with built-in constructs for string manipulation, floating point arithmetic, and input/output operations.

  15. Rapid Prototyping Reconsidered

    Science.gov (United States)

    Desrosier, James

    2011-01-01

    Continuing educators need additional strategies for developing new programming that can both reduce the time to market and lower the cost of development. Rapid prototyping, a time-compression technique adapted from the high technology industry, represents one such strategy that merits renewed evaluation. Although in higher education rapid…

  16. Studies on the runaway reaction of ABS polymerization process.

    Science.gov (United States)

    Hu, Kwan-Hua; Kao, Chen-Shan; Duh, Yih-Shing

    2008-11-15

    Taiwan has the largest acrylonitrile-butadiene-styrene (ABS) copolymer production in the world. Preventing on unexpected exothermic reactions and related emergency relief hazard is essential in the safety control of ABS emulsion polymerization. A VSP2 (Vent Sizing Package 2) apparatus is capable of studying both normal and abnormal conditions (e.g., cooling failure, mischarge, etc.) of industrial process. In this study, the scenarios were verified from the following abnormal conditions: loss of cooling, double charge of initiator, overcharge of monomer, without charge of solvent, and external fire. An external fire with constant heating will promote higher self-heat rate and this is recommended as the worst case scenario of emulsion polymerization on butadiene. Cooling failure coupled with bulk system of reactant was determined to be the credible worst case in ABS emulsion polymerization. Finally, the emergency vent sizing based on thermokinetics from VSP associated with DIERS methodology were used for evaluating the vent sizing and compared to that of the industrial plants.

  17. Studies on the runaway reaction of ABS polymerization process

    Energy Technology Data Exchange (ETDEWEB)

    Hu, K.-H. [Department of Occupational Safety and Health, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli, Taiwan (China); Kao, C.-S. [Department of Safety, Health and Environmental Engineering, National United University, Taiwan (China); Duh, Y.-S. [Department of Occupational Safety and Health, Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli, Taiwan (China)], E-mail: yihshingduh@yahoo.com.tw

    2008-11-15

    Taiwan has the largest acrylonitrile-butadiene-styrene (ABS) copolymer production in the world. Preventing on unexpected exothermic reactions and related emergency relief hazard is essential in the safety control of ABS emulsion polymerization. A VSP2 (Vent Sizing Package 2) apparatus is capable of studying both normal and abnormal conditions (e.g., cooling failure, mischarge, etc.) of industrial process. In this study, the scenarios were verified from the following abnormal conditions: loss of cooling, double charge of initiator, overcharge of monomer, without charge of solvent, and external fire. An external fire with constant heating will promote higher self-heat rate and this is recommended as the worst case scenario of emulsion polymerization on butadiene. Cooling failure coupled with bulk system of reactant was determined to be the credible worst case in ABS emulsion polymerization. Finally, the emergency vent sizing based on thermokinetics from VSP associated with DIERS methodology were used for evaluating the vent sizing and compared to that of the industrial plants.

  18. Convection induced by thermal gradients on thin reaction fronts

    Science.gov (United States)

    Ruelas Paredes, David R. A.; Vasquez, Desiderio A.

    2017-09-01

    We present a thin front model for the propagation of chemical reaction fronts in liquids inside a Hele-Shaw cell or porous media. In this model we take into account density gradients due to thermal and compositional changes across a thin interface. The front separating reacted from unreacted fluids evolves following an eikonal relation between the normal speed and the curvature. We carry out a linear stability analysis of convectionless flat fronts confined in a two-dimensional rectangular domain. We find that all fronts are stable to perturbations of short wavelength, but they become unstable for some wavelengths depending on the values of compositional and thermal gradients. If the effects of these gradients oppose each other, we observe a range of wavelengths that make the flat front unstable. Numerical solutions of the nonlinear model show curved fronts of steady shape with convection propagating faster than flat fronts. Exothermic fronts increase the temperature of the fluid as they propagate through the domain. This increment in temperature decreases with increasing speed.

  19. Gadolinium cation (Gd+) reaction with O2: Potential energy surface mapped experimentally and with theory

    Science.gov (United States)

    Demireva, Maria; Armentrout, P. B.

    2017-05-01

    Guided ion beam tandem mass spectrometry is used to measure the kinetic energy dependent cross sections for reactions of the lanthanide metal gadolinium cation (Gd+) and GdO+ with O2 and for collision-induced dissociation (CID) of GdO2+ with Xe. Gd+ reacts with O2 in an exothermic and barrierless reaction to form GdO+ and O. GdO2+ is also formed in this reaction, but this product ion is formed in a sequential reaction, as verified by pressure dependent measurements and comparison with the results for the reaction of GdO+ with O2. The CID experiments of GdO2+ indicate the presence of two GdO2+ precursor ion populations, assigned to a weakly bound oxygen molecule adduct (Gd+-O2) and an inserted cyclic Gd+ dioxide species (O-Gd+-O). Analysis of the resulting product ion cross sections yields bond dissociation energies (BDEs, D0) for Gd+-O2 and OGd+-O, where the latter BDE is also independently measured in an exchange reaction between GdO+ and O2. The CID experiments also provide the energy of the barrier for the rearrangement of the Gd+-O2 adduct to the inserted O-Gd+-O structure (as identified by loss of a single oxygen atom). The thermochemistry measured here yields D0(OGd+-O) = 2.86 ± 0.08 eV, D0(Gd+-O2) = 0.75 ± 0.11 eV, and a barrier height relative to Gd+-O2 of 0.31 ± 0.07 eV. These data are sufficient to characterize in some detail the potential energy surface of the Gd+ reaction with O2 entirely from experiment. Theoretical calculations are performed for comparison with the experimental energetics and for further insight into the reaction mechanisms.

  20. Gadolinium cation (Gd(+)) reaction with O2: Potential energy surface mapped experimentally and with theory.

    Science.gov (United States)

    Demireva, Maria; Armentrout, P B

    2017-05-07

    Guided ion beam tandem mass spectrometry is used to measure the kinetic energy dependent cross sections for reactions of the lanthanide metal gadolinium cation (Gd(+)) and GdO(+) with O2 and for collision-induced dissociation (CID) of GdO2(+) with Xe. Gd(+) reacts with O2 in an exothermic and barrierless reaction to form GdO(+) and O. GdO2(+) is also formed in this reaction, but this product ion is formed in a sequential reaction, as verified by pressure dependent measurements and comparison with the results for the reaction of GdO(+) with O2. The CID experiments of GdO2(+) indicate the presence of two GdO2(+) precursor ion populations, assigned to a weakly bound oxygen molecule adduct (Gd(+)-O2) and an inserted cyclic Gd(+) dioxide species (O-Gd(+)-O). Analysis of the resulting product ion cross sections yields bond dissociation energies (BDEs, D0) for Gd(+)-O2 and OGd(+)-O, where the latter BDE is also independently measured in an exchange reaction between GdO(+) and O2. The CID experiments also provide the energy of the barrier for the rearrangement of the Gd(+)-O2 adduct to the inserted O-Gd(+)-O structure (as identified by loss of a single oxygen atom). The thermochemistry measured here yields D0(OGd(+)-O) = 2.86 ± 0.08 eV, D0(Gd(+)-O2) = 0.75 ± 0.11 eV, and a barrier height relative to Gd(+)-O2 of 0.31 ± 0.07 eV. These data are sufficient to characterize in some detail the potential energy surface of the Gd(+) reaction with O2 entirely from experiment. Theoretical calculations are performed for comparison with the experimental energetics and for further insight into the reaction mechanisms.

  1. Reaction Mechanism of Mycobacterium Tuberculosis Glutamine Synthetase Using Quantum Mechanics/Molecular Mechanics Calculations.

    Science.gov (United States)

    Moreira, Cátia; Ramos, Maria J; Fernandes, Pedro Alexandrino

    2016-06-27

    This paper is devoted to the understanding of the reaction mechanism of mycobacterium tuberculosis glutamine synthetase (mtGS) with atomic detail, using computational quantum mechanics/molecular mechanics (QM/MM) methods at the ONIOM M06-D3/6-311++G(2d,2p):ff99SB//B3LYP/6-31G(d):ff99SB level of theory. The complete reaction undergoes a three-step mechanism: the spontaneous transfer of phosphate from ATP to glutamate upon ammonium binding (ammonium quickly loses a proton to Asp54), the attack of ammonia on phosphorylated glutamate (yielding protonated glutamine), and the deprotonation of glutamine by the leaving phosphate. This exothermic reaction has an activation free energy of 21.5 kcal mol(-1) , which is consistent with that described for Escherichia coli glutamine synthetase (15-17 kcal mol(-1) ). The participating active site residues have been identified and their role and energy contributions clarified. This study provides an insightful atomic description of the biosynthetic reaction that takes place in this enzyme, opening doors for more accurate studies for developing new anti-tuberculosis therapies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Spin-flip reactions of Zr + C2H6 researched by relativistic density functional theory.

    Science.gov (United States)

    Xiao, Yi; Chen, Xian-Yang; Qiu, Yi-Xiang; Wang, Shu-Guang

    2013-09-01

    Density functional theory (DFT) with relativistic corrections of zero-order regular approximation (ZORA) has been applied to explore the reaction mechanisms of ethane dehydrogenation by Zr atom with triplet and singlet spin-states. Among the complicated minimum energy reaction path, the available states involves three transition states (TS), and four stationary states (1) to (4) and one intersystem crossing with spin-flip (marked by -->): (3) Zr + C 2 H 6 → (3) Zr-CH 3 -CH 3 ((3)1) → (3)TS 1/2 → (3) ZrH-CH 2 -CH 3 ((3)2) → (3) TS 2/3 --> (1) ZrH2-CH2 = CH2 ((1) 3) → (1) TS 3/4 → (1) ZrH 3 -CH = CH 2 ((1)4). The minimum energy crossing point is determined with the help of the DFT fractional-occupation-number (FON) approach. The spin inversion leads the reaction pathway transferring from the triplet potential energy surface (PES) to the singlet's accompanying with the activation of the second C-H bond. The overall reaction is calculated to be exothermic by about 231 kJ mol(-1). Frequency and NBO analysis are also applied to confirm with the experimental observed data.

  3. Thermal decomposition of sugarcane straw, kinetics and heat of reaction in synthetic air.

    Science.gov (United States)

    Rueda-Ordóñez, Yesid Javier; Tannous, Katia

    2016-07-01

    The aim of this work was to analyze the thermal decomposition, kinetics and heat of reaction of sugarcane straw in synthetic air by thermogravimetry (TG) and differential scanning calorimetry (DSC). The TG and DSC experiments were carried out using heating rates of 2.5°C/min, 5°C/min, and 10°C/min, and particle diameter of 0.250mm. In the study of the smoldering reaction were identified three consecutive stages, drying, oxidative pyrolysis, and combustion. Thus, the kinetic pathway was composed by six independent parallel reactions, three for each stage after drying, in which the activation energies were 176, 313, 150, 80, 150, and 100kJ/mol. The heat of reaction in synthetic air was completely exothermic releasing 8MJ/kg. The modeled curves of thermal decomposition of sugarcane straw presented good agreement with experimental data. Then, the kinetic parameters obtained could be used to analyze different processes involving smoldering. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Rapid manufacturing facilitated customisation

    OpenAIRE

    Tuck, Christopher John; Hague, Richard; Ruffo, Massimiliano; Ransley, Michelle; Adams, Paul Russell

    2008-01-01

    Abstract This paper describes the production of body-fitting customised seat profiles utilising the following digital methods: three dimensional laser scanning, reverse engineering and Rapid Manufacturing (RM). The seat profiles have been manufactured in order to influence the comfort characteristics of an existing ejector seat manufactured by Martin Baker Aircraft Ltd. The seat, known as Navy Aircrew Common Ejection Seat (NACES), was originally designed with a generic profile. ...

  5. Rapid Detection of Pathogens

    Energy Technology Data Exchange (ETDEWEB)

    David Perlin

    2005-08-14

    Pathogen identification is a crucial first defense against bioterrorism. A major emphasis of our national biodefense strategy is to establish fast, accurate and sensitive assays for diagnosis of infectious diseases agents. Such assays will ensure early and appropriate treatment of infected patients. Rapid diagnostics can also support infection control measures, which monitor and limit the spread of infectious diseases agents. Many select agents are highly transmissible in the early stages of disease, and it is critical to identify infected patients and limit the risk to the remainder of the population and to stem potential panic in the general population. Nucleic acid-based molecular approaches for identification overcome many of the deficiencies associated with conventional culture methods by exploiting both large- and small-scale genomic differences between organisms. PCR-based amplification of highly conserved ribosomal RNA (rRNA) genes, intergenic sequences, and specific toxin genes is currently the most reliable approach for bacterial, fungal and many viral pathogenic agents. When combined with fluorescence-based oligonucleotide detection systems, this approach provides real-time, quantitative, high fidelity analysis capable of single nucleotide allelic discrimination (4). These probe systems offer rapid turn around time (<2 h) and are suitable for high throughput, automated multiplex operations that are critical for clinical diagnostic laboratories. In this pilot program, we have used molecular beacon technology invented at the Public health Research Institute to develop a new generation of molecular probes to rapidly detect important agents of infectious diseases. We have also developed protocols to rapidly extract nucleic acids from a variety of clinical specimen including and blood and tissue to for detection in the molecular assays. This work represented a cooperative research development program between the Kramer-Tyagi/Perlin labs on probe development

  6. Tiber Personal Rapid Transit

    Directory of Open Access Journals (Sweden)

    Diego Carlo D'agostino

    2011-02-01

    Full Text Available The project “Tiber Personal Rapid Transit” have been presented by the author at the Rome City Vision Competition1 2010, an ideas competition, which challenges architects, engineers, designers, students and creatives individuals to develop visionary urban proposals with the intention of stimulating and supporting the contemporary city, in this case Rome. The Tiber PRT proposal tries to answer the competition questions with the definition of a provocative idea: a Personal Rapid transit System on the Tiber river banks. The project is located in the central section of the Tiber river and aims at the renewal of the river banks with the insertion of a Personal Rapid Transit infrastructure. The project area include the riverbank of Tiber from Rome Transtevere RFI station to Piazza del Popolo, an area where main touristic and leisure attractions are located. The intervention area is actually no used by the city users and residents and constitute itself a strong barrier in the heart of the historic city.

  7. Hypersensitivity reactions to heparins.

    Science.gov (United States)

    Gonzalez-Delgado, Purificación; Fernandez, Javier

    2016-08-01

    This article provides an update on hypersensitivity reactions to heparins and novel oral anticoagulants, with special emphasis on diagnostic methods and management of patients. Although heparins are drugs widely used, hypersensitivity reactions are uncommon. Cutaneous delayed hypersensitivity reactions after subcutaneous administration affects up to 7.5% of patients. Heparin-induced thrombocytopenia is another unusual but severe condition in which early recognition is crucial. Immediate hypersensitivity reactions to heparins have been also reported, but with the novel oral anticoagulants are much more uncommon, although reports of exanthemas have been notified.Skin tests and subcutaneous provocation test are useful tools in the diagnosis of hypersensitivity reactions, except in heparin-induced thrombocytopenia in which biopsy of lesional skin and in-vitro tests are the modalities of choice to confirm the diagnosis.Management of hypersensitivity reactions includes finding an alternative depending on the type of reaction. Fondaparinux and novel oral anticoagulants may be safe alternatives. Delayed skin lesions after subcutaneous heparin are the most common type of hypersensitivity reactions, followed by life-threatening heparin-induced thrombocytopenia. Immediate reactions are uncommon. Allergologic studies may be useful to find an alternative option in patients with skin lesions in which heparin-induced thrombocytopenia has been previously excluded, as well as in heparin immediate reactions.

  8. Organocatalytic asymmetric assembly reactions for the syntheses of carbohydrate derivatives by intermolecular Michael-Henry reactions

    Science.gov (United States)

    Uehara, Hisatoshi; Imashiro, Ritsuo; Hernández-Torres, Gloria; Barbas, Carlos F.

    2010-01-01

    Given the significance of carbohydrates in life, medicine, and industry, the development of simple and efficient de novo methods to synthesize carbohydrates are highly desirable. Organocatalytic asymmetric assembly reactions are powerful tools to rapidly construct molecules with stereochemical complexity from simple precursors. Here, we present a simple and robust methodology for the asymmetric synthesis of pyranose derivatives with talo- and manno- configurations from simple achiral precursors through organocatalytic asymmetric intermolecular Michael–Henry reaction sequences. In this process, (tert-butyldimethylsilyloxy)acetaldehyde 1 was successfully utilized in two ways: as a donor in a highly selective anti-Michael reaction and as an acceptor in a consecutive Henry reaction. Varied nitroolefins served as Michael acceptors and varied aldehydes substituted for 1 as Henry acceptors providing for the construction of a wide range of carbohydrates with up to 5 stereocenters. In these reactions, a catalyst-controlled Michael reaction followed by a substrate-controlled Henry reaction provided 3,4-dideoxytalose derivatives 6 in a highly stereoselective manner. The Henry reaction was affected by addition of a simple base such as triethylamine: A complex chiral base was not necessary. 3,4-Dideoxymannose derivatives 7 were produced by simply changing the base from triethylamine to 1,8-diazabicyclo[5.4.0]undec-7-ene. Extension of this methodology to a syn-Michael initiated sequence was also successful. A mechanistic discussion is provided to explain the unusual substrate-induced stereoselectivity of the Henry reaction. PMID:20639468

  9. Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

    Directory of Open Access Journals (Sweden)

    Skrollan Stockinger

    2013-09-01

    Full Text Available A new approach for the investigation of a higher-order reaction by on-column reaction gas chromatography is presented. The reaction and the analytical separation are combined in a single experiment to investigate the Diels–Alder reaction of benzenediazonium-2-carboxylate as a benzyne precursor with various anthracene derivatives, i.e. anthracene, 9-bromoanthracene, 9-anthracenecarboxaldehyde and 9-anthracenemethanol. To overcome limitations of short reaction contact times at elevated temperatures a novel experimental setup was developed involving a cooling trap to achieve focusing and mixing of the reactants at a defined spot in a fused-silica capillary. This trap functions as a reactor within the separation column in the oven of a gas chromatograph. The reactants are sequentially injected to avoid undefined mixing in the injection port. An experimental protocol was developed with optimized injection intervals and cooling times to achieve sufficient conversions at short reaction times. Reaction products were rapidly identified by mass spectrometric detection. This new approach represents a practical procedure to investigate higher-order reactions at an analytical level and it simultaneously provides valuable information for the optimization of the reaction conditions.

  10. Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping.

    Science.gov (United States)

    Stockinger, Skrollan; Trapp, Oliver

    2013-01-01

    A new approach for the investigation of a higher-order reaction by on-column reaction gas chromatography is presented. The reaction and the analytical separation are combined in a single experiment to investigate the Diels-Alder reaction of benzenediazonium-2-carboxylate as a benzyne precursor with various anthracene derivatives, i.e. anthracene, 9-bromoanthracene, 9-anthracenecarboxaldehyde and 9-anthracenemethanol. To overcome limitations of short reaction contact times at elevated temperatures a novel experimental setup was developed involving a cooling trap to achieve focusing and mixing of the reactants at a defined spot in a fused-silica capillary. This trap functions as a reactor within the separation column in the oven of a gas chromatograph. The reactants are sequentially injected to avoid undefined mixing in the injection port. An experimental protocol was developed with optimized injection intervals and cooling times to achieve sufficient conversions at short reaction times. Reaction products were rapidly identified by mass spectrometric detection. This new approach represents a practical procedure to investigate higher-order reactions at an analytical level and it simultaneously provides valuable information for the optimization of the reaction conditions.

  11. Reliable, rapid and simple voltammetric detection of urea nitrate explosive.

    Science.gov (United States)

    Cagan, Avi; Lu, Donglai; Cizek, Karel; La Belle, Jeff; Wang, Joseph

    2008-05-01

    A highly selective and rapid electrochemical assay of the improvised explosive urea nitrate (UN) is reported. The method involves a short ( approximately 10 s) acid-catalyzed reaction of UN with 4-nitrotoluene (NT) followed by a rapid ( approximately 2 s) square-wave voltammetric (SWV) detection of the 2,4-dinitrotoluene (DNT) product. The new protocol offers great promise for a reliable field detection of UN, with significant advantages of speed, sensitivity, portability, simplicity, and cost.

  12. The application of reaction engineering to biocatalysis

    DEFF Research Database (Denmark)

    Ringborg, Rolf Hoffmeyer; Woodley, John

    2016-01-01

    outline the benefits of reaction engineering in this development process, with particular emphasis of reaction kinetics. Future research needs to focus on rapid methods to collect such data at sufficient accuracy that it can be used forthe effective design of new biocatalytic processes.......Biocatalysis is a growing area of synthetic and process chemistry with the ability to deliver not only improved processes for the synthesis of existing compounds, but also new routes to new compounds. In order to assess the many options and strategies available to an engineer developing a new...

  13. Reaction kinetics of polybutylene terephthalate polycondensation reaction

    NARCIS (Netherlands)

    Darda, P. J.; Hogendoorn, J. A.; Versteeg, G. F.; Souren, F.

    2005-01-01

    The kinetics of the forward polycondensation reaction of polybutylene terephthalate (PBT) has been investigated using thermogravimetric analysis (TGA). PBT - prepolymer with an initial degree of polymerization of 5.5 was used as starting material. The PBT prepolymer was prepared from dimethyl

  14. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard

    2009-01-01

    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  15. Desosamine in multicomponent reactions

    NARCIS (Netherlands)

    Achatz, Sepp; Dömling, Alexander

    2006-01-01

    Desosamine occurring ubiquitously in natural products is introduced into isocyanide based multicomponent reaction chemistry. Corresponding products are of potential interest for the design of novel antibiotics. © 2006.

  16. Pathways for the OH + Br2 → HOBr + Br and HOBr + Br → HBr + BrO Reactions.

    Science.gov (United States)

    Wang, Hongyan; Qiu, Yudong; Schaefer, Henry F

    2016-02-11

    The OH radical reaction with Br2 and the subsequent reaction HOBr + Br are of exceptional importance to atmospheric chemistry and environmental chemistry. The entrance complex, transition state, and exit complex for both reactions have been determined using the coupled-cluster method with single, double, and perturbative triple excitations CCSD(T) with correlation consistent basis sets up to size cc-pV5Z and cc-pV5Z-PP. Coupled cluster effects with full triples (CCSDT) and full quadruples (CCSDTQ) are explicitly investigated. Scalar relativistic effects, spin-orbit coupling, and zero-point vibrational energy corrections are evaluated. The results from the all-electron basis sets are compared with those from the effective core potential (ECP) pseudopotential (PP) basis sets. The results are consistent. The OH + Br2 reaction is predicted to be exothermic 4.1 ± 0.5 kcal/mol, compared to experiment, 3.9 ± 0.2 kcal/mol. The entrance complex HO···BrBr is bound by 2.2 ± 0.2 kcal/mol. The transition state lies similarly well below the reactants OH + Br2. The exit complex HOBr···Br is bound by 2.7 ± 0.6 kcal/mol relative to separated HOBr + Br. The endothermicity of the reaction HOBr + Br → HBr + BrO is 9.6 ± 0.7 kcal/mol, compared with experiment 8.7 ± 0.3 kcal/mol. For the more important reverse (exothermic) HBr + BrO reaction, the entrance complex BrO···HBr is bound by 1.8 ± 0.6 kcal/mol. The barrier for the HBr + BrO reaction is 6.8 ± 0.9 kcal/mol. The exit complex (Br···HOBr) for the HBr + BrO reaction is bound by 1.9 ± 0.2 kcal/mol with respect to the products HOBr + Br.

  17. Rapidly variable relatvistic absorption

    Science.gov (United States)

    Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

    2017-10-01

    I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

  18. Rapid prototype and test

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, D.L.; Hansche, B.D.

    1996-06-01

    In order to support advanced manufacturing, Sandia has acquired the capability to produce plastic prototypes using stereolithography. Currently, these prototypes are used mainly to verify part geometry and ``fit and form`` checks. This project investigates methods for rapidly testing these plastic prototypes, and inferring from prototype test data actual metal part performance and behavior. Performances examined include static load/stress response, and structural dynamic (modal) and vibration behavior. The integration of advanced non-contacting measurement techniques including scanning laser velocimetry, laser holography, and thermoelasticity into testing of these prototypes is described. Photoelastic properties of the epoxy prototypes to reveal full field stress/strain fields are also explored.

  19. Right-Rapid-Rough

    Science.gov (United States)

    Lawrence, Craig

    2003-01-01

    IDEO (pronounced 'eye-dee-oh') is an international design, engineering, and innovation firm that has developed thousands of products and services for clients across a wide range of industries. Its process and culture attracted the attention of academics, businesses, and journalists around the world, and are the subject of a bestselling book, The Art of Innovation by Tom Kelley. One of the keys to IDEO's success is its use of prototyping as a tool for rapid innovation. This story covers some of IDEO's projects, and gives reasons for why they were successful.

  20. Method for rapidly determining a pulp kappa number using spectrophotometry

    Science.gov (United States)

    Chai, Xin-Sheng; Zhu, Jun Yong

    2002-01-01

    A system and method for rapidly determining the pulp kappa number through direct measurement of the potassium permanganate concentration in a pulp-permanganate solution using spectrophotometry. Specifically, the present invention uses strong acidification to carry out the pulp-permanganate oxidation reaction in the pulp-permanganate solution to prevent the precipitation of manganese dioxide (MnO.sub.2). Consequently, spectral interference from the precipitated MnO.sub.2 is eliminated and the oxidation reaction becomes dominant. The spectral intensity of the oxidation reaction is then analyzed to determine the pulp kappa number.

  1. Rapid mineralocorticoid receptor trafficking.

    Science.gov (United States)

    Gekle, M; Bretschneider, M; Meinel, S; Ruhs, S; Grossmann, C

    2014-03-01

    The mineralocorticoid receptor (MR) is a ligand-dependent transcription factor that physiologically regulates water-electrolyte homeostasis and controls blood pressure. The MR can also elicit inflammatory and remodeling processes in the cardiovascular system and the kidneys, which require the presence of additional pathological factors like for example nitrosative stress. However, the underlying molecular mechanism(s) for pathophysiological MR effects remain(s) elusive. The inactive MR is located in the cytosol associated with chaperone molecules including HSP90. After ligand binding, the MR monomer rapidly translocates into the nucleus while still being associated to HSP90 and after dissociation from HSP90 binds to hormone-response-elements called glucocorticoid response elements (GREs) as a dimer. There are indications that rapid MR trafficking is modulated in the presence of high salt, oxidative or nitrosative stress, hypothetically by induction or posttranslational modifications. Additionally, glucocorticoids and the enzyme 11beta hydroxysteroid dehydrogenase may also influence MR activation. Because MR trafficking and its modulation by micro-milieu factors influence MR cellular localization, it is not only relevant for genomic but also for nongenomic MR effects. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Rapid response manufacturing (RRM)

    Energy Technology Data Exchange (ETDEWEB)

    Cain, W.D. [Lockheed Martin Energy Systems, Inc., Oak Ridge, TN (United States); Waddell, W.L. [National Centers for Manufacturing Sciences, Ann Arbor, MI (United States)

    1997-02-18

    US industry is fighting to maintain its competitive edge in the global market place. Today markets fluctuate rapidly. Companies, to survive, have to be able to respond with quick-to-market, improved, high quality, cost efficient products. The way products are developed and brought to market can be improved and made more efficient through the proper incorporation of emerging technologies. The RRM project was established to leverage the expertise and resources of US private industries and federal agencies to develop, integrate, and deploy new technologies that meet critical needs for effective product realization. The RRM program addressed a needed change in the US Manufacturing infrastructure that will ensure US competitiveness in world market typified by mass customization. This project provided the effort needed to define, develop and establish a customizable infrastructure for rapid response product development design and manufacturing. A major project achievement was the development of a broad-based framework for automating and integrating the product and process design and manufacturing activities involved with machined parts. This was accomplished by coordinating and extending the application of feature-based product modeling, knowledge-based systems, integrated data management, and direct manufacturing technologies in a cooperative integrated computing environment. Key technological advancements include a product model that integrates product and process data in a consistent, minimally redundant manner, an advanced computer-aided engineering environment, knowledge-based software aids for design and process planning, and new production technologies to make products directly from design application software.

  3. Acute leukaemoid reaction following cardiac surgery

    Directory of Open Access Journals (Sweden)

    Webb Stephen T

    2007-01-01

    Full Text Available Abstract Chronic myelomonocytic leukaemia is an atypical myeloproliferative disorder with a natural history of progression to acute myeloid leukaemia, a complex and poorly understood response by the bone marrow to stress. Cardiac surgery activates many inflammatory cascades and may precipitate a systemic inflammatory response syndrome. We present a case of undiagnosed chronic myelomonocytic leukaemia who developed rapidly fatal multi-organ dysfunction following cardiac surgery due to an acute leukaemoid reaction.

  4. Propionate exchange reactions in methanogenic ecosystems.

    Science.gov (United States)

    Boone, D R

    1984-10-01

    Propionate degradation was measured with [1-C]- and [2-C]propionate in an anaerobic digestor. When [1-C]propionate was used, label disappeared more rapidly from the propionate pool than when [2-C]propionate was used. This indicated that an exchange reaction involving the carboxyl group of propionate occurred. Labeled propionate added to digestor samples which were equilibrated with H(2) lost label from the carboxyl group but not from the methylene group.

  5. Reactions to Attitudinal Deviancy.

    Science.gov (United States)

    Levine, John M.; Allen, Vernon L.

    This paper presents a critical review of empirical and theoretical treatments of group reaction to attitudinal deviancy. Inspired by Festinger's (1950) ideas on resolution of attitudinal discrepancies in groups, Schachter (1951) conducted an experiment that has greatly influenced subsequent research and theory concerning reaction to attitudinal…

  6. ORGANIC REACTION MECHANISM CONTROVERSY ...

    African Journals Online (AJOL)

    Preferred Customer

    Chemists, educators and students are entitled to their mental constructs about reaction mechanism in the classroom. What pedagogical implications have these knowledge claims for teaching and learning reaction mechanisms in organic chemistry? This is the main interest of the paper. Thus three questions were critically ...

  7. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  8. Applications of Reaction Rate

    Science.gov (United States)

    Cunningham, Kevin

    2007-01-01

    This article presents an assignment in which students are to research and report on a chemical reaction whose increased or decreased rate is of practical importance. Specifically, students are asked to represent the reaction they have chosen with an acceptable chemical equation, identify a factor that influences its rate and explain how and why it…

  9. Transverse flow reactor studies of the dynamics of radical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Macdonald, R.G. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Radical reactions are in important in combustion chemistry; however, little state-specific information is available for these reactions. A new apparatus has been constructed to measure the dynamics of radical reactions. The unique feature of this apparatus is a transverse flow reactor in which an atom or radical of known concentration will be produced by pulsed laser photolysis of an appropriate precursor molecule. The time dependence of individual quantum states or products and/or reactants will be followed by rapid infrared laser absorption spectroscopy. The reaction H + O{sub 2} {yields} OH + O will be studied.

  10. Computational calorimetric study of the iron ore reduction reactions in mixtures with coal

    Energy Technology Data Exchange (ETDEWEB)

    Strezov, V.; Liu, G.S.; Lucas, J.A.; Wibberley, L.J. [Macquarie University, North Ryde, NSW (Australia). Graduate School of the Environment

    2005-02-02

    Thermal analysis on two coals (semi-anthracite and high-volatile coking coal), iron ore, and their corresponding mixtures was performed using a computer-aided thermal analysis technique. Samples were heated to 1000{sup o}C at a typical rate of 10{sup o}C/min under an argon atmosphere. It, was found that the iron ore undergoes several reactions prior to its reduction, which resulted in an endothermic heat effect. The iron ore reduction commenced at temperatures as low as 580{sup o}C and progressively increased at higher temperatures. Coal devolatilization was found to play an important role in iron ore reduction for the coal-ore mixtures at temperatures below 920{sup o}C, while the effect of char gasification resulting in CO as a reducing gas was dominant at higher temperatures. No apparent difference in the effect of coal devolatilization on reduction reactions was observed when low- and high-volatile matter coal was mixed with the iron ore. The main difference was detected only in the temperature range where char gasification became prominent and was predominantly responsible for the reduction of the iron ore. Similarities in the endothermic and exothermic peaks were found at different heating rates, indicating a unified reaction mechanism between them. However, the peaks shifted toward the higher temperature range under increased heating rates.

  11. Solar photo-thermal catalytic reactions to produce high value chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Prengle, Jr, H W; Wentworth, W E [Houston Univ., TX (United States)

    1992-04-01

    This report presents a summary of the research work accomplished to date on the utilization of solar photo-thermal energy to convert low cost chemical feedstocks into high $-value chemical products. The rationale is that the solar IR-VIS-UV spectrum is unique, supplying endothermic reaction energy as well as VIS-UV for photochemical activation. Chemical market analysis and product price distribution focused attention on speciality chemicals with prices >$1.00/lb, and a synthesis sequence of n-paraffins to aromatics to partial oxidized products. The experimental work has demonstrated that enhanced reaction effects result from VIS-UV irradiation of catalytically active V2O5/SiO2. Experiments of the past year have been on dehydrogenation and dehydrocyclization of n-paraffins to olefins and aromatics with preference for the latter. Recent results using n-hexane produced 95% conversion with 56% benzene; it is speculated that aromatic yield should reach {approximately}70% by further optimization. Pilot- and commercial-scale reactor configurations have been examined; the odds-on-favorite being a shallow fluid-bed of catalyst with incident radiation from the top. Sequencing for maximum cost effectiveness would be day-time endothermic followed by night-time exothermic reactions to produce the products.

  12. Understanding the Reaction Mechanism of Glycerol Hydrogenolysis over a CuCr2 O4 Catalyst.

    Science.gov (United States)

    Yun, Yang Sik; Kim, Tae Yong; Yun, Danim; Lee, Kyung Rok; Han, Jeong Woo; Yi, Jongheop

    2017-01-20

    The reaction mechanism of glycerol hydrogenolysis to 1,2-propanediol over a spinel CuCr2 O4 catalyst was investigated by using DFT calculations. Theoretical models were developed from the results of experimental characterization. Adsorption configurations and energetics of the reactant, intermediates, final product, and transition states were calculated on Cu(1 1 1) and CuCr2 O4 (1 0 0). Based on our DFT results, we found that the formation of acetol is preferred to that of 3-hydroxypropionaldehyde thermodynamically and kinetically on both surfaces. For glycerol hydrogenolysis to 1,2-propanediol, the CuCr2 O4 surface is less exothermic but more kinetically favorable than the Cu surface. The low activation barrier during the reaction on the CuCr2 O4 surface is attributed to the unique surface structure; the cubic spinel structure provides a stable adsorption site on which reactants are allowed to be dehydrated and hydrogenated easily with the characteristic adsorption configuration. The role of the Cu and Cr atoms in a CuCr2 O4 surface were revealed. The results of reaction tests supported our theoretical calculations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Benzene destruction in claus process by sulfur dioxide: A reaction kinetics study

    KAUST Repository

    Sinha, Sourab

    2014-07-02

    Benzene, toluene and xylene (BTX) are present as contaminants in the H 2S gas stream entering a Claus furnace. The exhaust gases from the furnace enter catalytic units, where BTX form soot particles. These particles clog and deactivate the catalysts. A solution to this problem is BTX oxidation before the gases enter catalyst beds. This work presents a theoretical investigation on benzene oxidation by SO2. Density functional theory is used to develop a detailed mechanism for phenyl radical -SO2 interactions. The mechanism begins with SO2 addition to phenyl radical after overcoming an energy barrier of 6.4 kJ/mol. This addition reaction is highly exothermic, where a reaction energy of 182 kJ/mol is released. The most favorable pathway involves O-S bond breakage, leading to the release of SO. A remarkable similarity between the pathways for phenyl radical oxidation by O2 and its oxidation by SO2 is observed. The reaction rate constants are also evaluated to facilitate process simulations. © 2014 American Chemical Society.

  14. Site and bond-specific dynamics of reactions at the gas-liquid interface.

    Science.gov (United States)

    Tesa-Serrate, Maria A; King, Kerry L; Paterson, Grant; Costen, Matthew L; McKendrick, Kenneth G

    2014-01-07

    The dynamics of the interfacial reactions of O((3)P) with the hydrocarbon liquids squalane (C30H62, 2,6,10,15,19,23-hexamethyltetracosane) and squalene (C30H50, trans-2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaene) have been studied experimentally. Laser-induced fluorescence (LIF) was used to detect the nascent gas-phase OH products. The O((3)P) atoms are acutely sensitive to the chemical differences of the squalane and squalene surfaces. The larger exothermicity of abstraction from allylic C-H sites in squalene is reflected in markedly hotter OH rotational and vibrational distributions. There is a more modest increase in translational energy release. A larger fraction of the available energy is deposited in the liquid for squalene than for squalane, consistent with a more extensive geometry change on formation of the allylic radical co-product. Although the dominant reaction mechanism is direct, impulsive scattering, there is some evidence for OH being accommodated at both liquid surfaces, resulting in thermalised translation and rotational distributions. Despite the H-abstraction reaction being strongly favoured energetically for squalene, the yield of OH is substantially lower than for squalane. This is very likely due to competitive addition of O((3)P) to the unsaturated sites in squalene, implying that double bonds are extensively exposed at the liquid surface.

  15. Direct Energy Supply to the Reaction Mixture during Microwave-Assisted Hydrothermal and Combustion Synthesis of Inorganic Materials

    Directory of Open Access Journals (Sweden)

    Roberto Rosa

    2014-05-01

    Full Text Available The use of microwaves to perform inorganic synthesis allows the direct transfer of electromagnetic energy inside the reaction mixture, independently of the temperature manifested therein. The conversion of microwave (MW radiation into heat is useful in overcoming the activation energy barriers associated with chemical transformations, but the use of microwaves can be further extended to higher temperatures, thus creating unusual high-energy environments. In devising synthetic methodologies to engineered nanomaterials, hydrothermal synthesis and solution combustion synthesis can be used as reference systems to illustrate effects related to microwave irradiation. In the first case, energy is transferred to the entire reaction volume, causing a homogeneous temperature rise within a closed vessel in a few minutes, hence assuring uniform crystal growth at the nanometer scale. In the second case, strong exothermic combustion syntheses can benefit from the application of microwaves to convey energy to the reaction not only during the ignition step, but also while it is occurring and even after its completion. In both approaches, however, the direct interaction of microwaves with the reaction mixture can lead to practically gradient-less heating profiles, on the basis of which the main observed characteristics and properties of the aforementioned reactions and products can be explained.

  16. Al-Si/Al2O3 in situ composite prepared by displacement reaction of CuO/Al system

    Directory of Open Access Journals (Sweden)

    Zhang Jing

    2010-02-01

    Full Text Available Al2O3 particle-reinforced ZL109 composite was prepared by in situ reaction between CuO and Al. The microstructure was observed by means of OM, SEM and TEM. The Al2O3 particles in sub-micron sizes distribute uniformly in the matrix, and the Cu displaced from the in situ reaction forms net-like alloy phases with other alloy elements. The hardness and the tensile strength of the composites at room temperature have a slight increase as compared to that of the matrix. However, the tensile strength at 350 ℃ has reached 90.23 MPa, or 16.92 MPa higher than that of the matrix. The mechanism of the reaction in the CuO/Al system was studied by using of differential scanning calorimetry(DSC and thermodynamic calculation. The reaction between CuO and Al involves two steps. First, CuO reacts with Al to form Cu2O and Al2O3 at the melting temperature of the matrix alloy, and second, Cu2O reacts with Al to form Cu and Al2O3 at a higher temperature. At ZL109 casting temperature of 750–780 ℃, the second step can also take place because of the effect of exothermic reaction of the first step.

  17. Rapid Refresh (RAP) [13 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental...

  18. Rapid Refresh (RAP) [20 km

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Rapid Refresh (RAP) numerical weather model took the place of the Rapid Update Cycle (RUC) on May 1, 2012. Run by the National Centers for Environmental...

  19. Reaction of uranocenes with nitro compounds

    Energy Technology Data Exchange (ETDEWEB)

    Grant, C.B.; Streitwieser, A. Jr.

    1978-04-12

    Uranocenes (di-eta/sup 8/-cyclooctatetraeneuranium) are relatively stable to many neutral oxygen-containing organic compounds but react rapidly with aromatic and aliphatic nitro compounds to liberate the cyclooctatetraene ligand in quantitative yield and form azo compounds, often in good yield but in some cases with formation also of the corresponding amines. p-Nitrotoluene reacts more slowly than nitrobenzene. Additional studies of reaction mechanism show that free nitro radical anions or nitrenes do not appear to be involved, but free nitroso compounds are probable intermediates. Azoxy compounds react more slowly with uranocenes and cannot be intermediates in the reactions of nitro compounds. The reaction has few analogies. 67 references, 3 tables.

  20. Development and implementation of a rapid real-time polymerase ...

    African Journals Online (AJOL)

    Assays which use real-time polymerase chain reaction (PCR) technology can be developed for the rapid identification of genetic sequences carried by waterborne pathogens. Rand Water has established facilities within which a selection of PCR assays will be developed. This paper reports on the optimisation and ...

  1. Development and implementation of a rapid real-time polymerase ...

    African Journals Online (AJOL)

    6–10 May 2012. * To whom all correspondence should be addressed. ☎ +27 16 430-8403; fax: +27 16 455-2055; e-mail: nleat@randwater.co.za. Development and implementation of a rapid real-time polymerase chain reaction assay for the detection of toxigenic Vibrio cholerae in water. Neil Leat* and Monique Grundlingh.

  2. Formation of nitrogen-containing polycyclic cations by gas-phase and intracluster reactions of acetylene with the pyridinium and pyrimidinium ions.

    Science.gov (United States)

    Soliman, Abdel-Rahman; Hamid, Ahmed M; Attah, Isaac; Momoh, Paul; El-Shall, M Samy

    2013-01-09

    Here, we present evidence from laboratory experiments for the formation of nitrogen-containing complex organic ions by sequential reactions of acetylene with the pyridinium and pyrimidinium ions in the gas phase and within ionized pyridine-acetylene binary clusters. Additions of five and two acetylene molecules onto the pyridinium and pyrimidinium ions, respectively, at room temperature are observed. Second-order rate coefficients of the overall reaction of acetylene with the pyridinium and pyrimidinium ions are measured as 9.0 × 10(-11) and 1.4 × 10(-9) cm(3) s(-1), respectively, indicating reaction efficiencies of about 6% and 100%, respectively, at room temperature. At high temperatures, only two acetylene molecules are added to the pyridinium and pyrimidinium ions, suggesting covalent bond formation. A combination of ion dissociation and ion mobility experiments with DFT calculations reveals that the addition of acetylene into the pyridinium ion occurs through the N-atom of the pyridinium ion. The relatively high reaction efficiency is consistent with the absence of a barrier in the exothermic N-C bond forming reaction leading to the formation of the C(7)H(7)N(•+) covalent adduct. An exothermic addition/H-elimination reaction of acetylene with the C(7)H(7)N(•+) adduct is observed leading to the formation of a bicyclic quinolizinium cation (C(9)H(8)N(+)). Similar chemistry is observed in the sequential reactions of acetylene with the pyrimidinium ion. The second acetylene addition onto the pyrimidinium ion involves an exclusive addition/H-elimination reaction at room temperature leading to the formation of a bicyclic pyrimidinium cation (C(8)H(7)N(2)(+)). The high reactivity of the pyridinium and pyrimidinium ions toward acetylene is in sharp contrast to the very low reactivity of the benzene cation, which has a reaction efficiency of 10(-4)-10(-5). This indicates that the presence of a nitrogen atom within the aromatic ring enhances the ring growth

  3. Respiratory transfusion reactions

    Directory of Open Access Journals (Sweden)

    Ivica Marić

    2017-11-01

    Full Text Available Respiratory transfusion-related reactions are not very frequent, partly also because recognition and reporting transfusion reactions is still underemphasized. Tis article describes the most important respiratory transfusion reactions, their pathophysiology, clinical picture and treatment strategies. Respiratory transfusion related reactions can be primary or secondary. The most important primary transfusion-related reactions are TRALI - transfusion-related acute lung injury, TACO – transfusion-associated circulatory overload, and TAD - transfusion-associated dyspnea. TRALI is immuneassociated injury of alveolar basal membrane, which becomes highly permeable and causes noncardiogenic pulmonary edema. Treatment of TRALI is mainly supportive with oxygen, fluids (in case of hypotension and in cases of severe acute respiratory failure also mechanic ventilation. TACO is caused by volume overload in predisposed individuals, such as patients with heart failure, the elderly, infants, patients with anemia and patients with positive fluid balance. Clinical picture is that of a typical pulmonary cardiogenic edema, and the therapy is classical: oxygen and diuretics, and in severe cases also non-invasive or invasive mechanical ventilation. TAD is usually a mild reaction of unknown cause and cannot be classified as TACO or TRALI, nor can it be ascribed to patient’s preexisting diseases. Although the transfusion-related reactions are not very common, knowledge about them can prevent serious consequences. On the one hand preventive measures should be sought, and on the other early recognition is beneficial, so that proper treatment can take place.

  4. Autocatalysis in Reaction Networks

    OpenAIRE

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2013-01-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view to...

  5. The Reaction Wheel Pendulum

    CERN Document Server

    Block, Daniel J; Spong, Mark W

    2007-01-01

    This monograph describes the Reaction Wheel Pendulum, the newest inverted-pendulum-like device for control education and research. We discuss the history and background of the reaction wheel pendulum and other similar experimental devices. We develop mathematical models of the reaction wheel pendulum in depth, including linear and nonlinear models, and models of the sensors and actuators that are used for feedback control. We treat various aspects of the control problem, from linear control of themotor, to stabilization of the pendulum about an equilibrium configuration using linear control, t

  6. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  7. Rapid and precise genotyping of porcine microsatellites.

    Science.gov (United States)

    Yue, G H; Beeckmann, P; Bartenschlager, H; Moser, G; Geldermann, H

    1999-11-01

    Microsatellites are useful markers for genetic mapping and linkage analysis because they are highly polymorphic, abundant in genomes and relatively easily scored with polymerase chain reaction (PCR). A rapid genotyping system for microsatellites was developed, which included multiplex PCRs, multiple use of Hydrolink gels, automated fluorescent detection of fragments on an A.L.F. DNA sequencer, automatic assignment of alleles to each locus and verification of genotypes with a self-developed computer program "Fragtest". Eight multiplex PCRs have been developed to genotype 29 microsatellites for genetic and quantitative trait loci (QTL) mapping on pig chromosomes 6, 7, 12 and 13. Three to six microsatellites could be amplified in one multiplex PCR. Each multiplex reaction required only different concentrations of each pair of primers and a low concentration of dNTP (100 microM). A dNTP concentration of 100 microM proved to be optimal for the coamplification of microsatellites under the concentration of 1.5 mM MgCl2. Using four internal size standards added in each sample, the 5% Hydrolink gel could subsequently be used up to five times (total running time of 500 min) on the A.L.F. automated sequencer without significant loss of resolution and precision of fragment length analysis. Automatic assignment of alleles on each locus using "Fragtest" significantly increased the efficiency and precision of the genotyping. This system is thus a rapid, cheap, and highly discriminating genotyping system.

  8. Rapid Color Test Identification System for Screening of Counterfeit Fluoroquinolone

    Directory of Open Access Journals (Sweden)

    B. K. Singh

    2009-01-01

    Full Text Available The protocol of rapid identification system consists of three chemical color reactions; two group tests for fluoroquinolone class and a compound specific test each for norfloxacin, ciprofloxacin, gatifloxacin, ofloxacin, levofloxacin and sparfloxacin. The group color reactions are based on (a Oxidizing behavior of quinolone and (b Fluorine functional groups, both of which are characteristic of fluoroquinolone class. The compound specific color reactions are developed taking into consideration unique chemical behavior of each compound. The proposed chemical color tests have high selectivity⁄specificity, are ideal for screening purpose. The color of each test was defined by two standard color systems namely CIE lab and Munsell color. A suspected counterfeit tablet of any of the above mentioned drugs can be identified within 10-15 min using this rapid identification system.

  9. Reaction between HN and SN: a possible channel for the interstellar formation of N2 and SH in the cold interstellar clouds.

    Science.gov (United States)

    Bhasi, Priya; Nhlabatsi, Zanele P; Sitha, Sanyasi

    2015-12-28

    Using computational calculations the potential energy surface (PES) of the reaction between NH and NS has been analysed. The PES of the reaction shows the formation of two very stable species, HNSN and HNNS. Out of these two, HNNS which has the signature N-N linkage was found to be the most stable species in the PES. In view of the highly exothermic nature of the reaction surface, it has been proposed that these two species can possibly be detected in the interstellar space. For the first time it has also been shown that the reaction between the NH and NS can lead to the possible formation of N2via the isomer HNNS, and how the effect of tunnelling can make this reaction very much feasible, even under the extremely low temperature conditions prevailing in the interstellar medium. Based on the already reported results, a similar kind of behaviour for the NH + NO reaction surface has also been proposed. These dissociation reactions leading to the formation of N2 can be considered as potential secondary contributing channels while accounting for the total estimates of N2 in the interstellar medium, and thus HNNS as well as HNNO can be considered as stable reservoir molecules for interstellar N2. Besides the formation of N2, the formation of another astronomically important radical, SH in the cold interstellar clouds, has also been proposed.

  10. Autocatalysis in reaction networks.

    Science.gov (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2014-10-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  11. [Adverse reactions to vaccines].

    Science.gov (United States)

    Ito Tsuchiya, F M; Rosas Vargas, M A; Zepeda Ortega, B; Río del Navarro, Blanca Estela; Sienra Monge, Juan José Luis

    2007-01-01

    Vaccination is one of the medicine's achievements to control and/or eradicate certain infectious diseases. Vaccines contain antigenic doses derived from microorganisms and/or its toxins, besides they are composed of other substances such as aluminum, gelatin, egg proteins, mercury components (as thimerosal), and antibiotics; therefore, these substances can produce hypersensitivity reactions. The above-mentioned reactions can be evidenced with itch, edema, hives, asthmatic crisis, hypotension and even anaphylactic shock. Due to the importance of vaccination, especially in childhood, it is essential to know the benefits of vaccines, their impact in morbidity and mortality decrease of certain infected-contagious diseases, as well as the adverse effects and the allergic reactions to their application. As immunizations prevent natural infections, they might contribute to a free infectious environment that would allow atopic response. This paper reviews the allergic reactions to vaccines and their influence on the development of atopic disease.

  12. Bad Reaction to Cosmetics?

    Science.gov (United States)

    ... Consumers Protect Yourself Health Fraud Bad Reactions to Cosmetics? Tell FDA! Share Tweet Linkedin Pin it More ... Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products

  13. Firefighter Nozzle Reaction

    DEFF Research Database (Denmark)

    Chin, Selena K.; Sunderland, Peter B.; Jomaas, Grunde

    2017-01-01

    to anchor forces, the hose becomes straight. The nozzle reaction is found to equal the jet momentum flow rate, and it does not change when an elbow connects the hose to the nozzle. A forward force must be exerted by a firefighter or another anchor that matches the forward force that the jet would exert...... on a perpendicular wall. Three reaction expressions are derived, allowing it to be determined in terms of hose diameter, jet diameter, flow rate, and static pressure upstream of the nozzle. The nozzle reaction predictions used by the fire service are 56% to 90% of those obtained here for typical firefighting hand......Nozzle reaction and hose tension are analyzed using conservation of fluid momentum and assuming steady, inviscid flow and a flexible hose in frictionless contact with the ground. An expression that is independent of the bend angle is derived for the hose tension. If this tension is exceeded owing...

  14. Chemical burn or reaction

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000059.htm Chemical burn or reaction To use the sharing features on ... the burned area from pressure and friction. Minor chemical burns will generally heal without further treatment. However, if ...

  15. Building a rapid response team.

    Science.gov (United States)

    Halvorsen, Lisa; Garolis, Salomeja; Wallace-Scroggs, Allyson; Stenstrom, Judy; Maunder, Richard

    2007-01-01

    The use of rapid response teams is a relatively new approach for decreasing or eliminating codes in acute care hospitals. Based on the principles of a code team for cardiac and/or respiratory arrest in non-critical care units, the rapid response teams have specially trained nursing, respiratory, and medical personnel to respond to calls from general care units to assess and manage decompensating or rapidly changing patients before their conditions escalate to a full code situation. This article describes the processes used to develop a rapid response team, clinical indicators for triggering a rapid response team call, topics addressed in an educational program for the rapid response team members, and methods for evaluating effectiveness of the rapid response team.

  16. Adverse reaction to tetrazepam.

    Science.gov (United States)

    Palacios Benito, R; Domínguez Ortega, J; Alonso Llamazares, A; Rodríguez Morales, A; Plaza Díaz, A; Chamorro Gómez, M; Martínez-Cócera, C

    2001-01-01

    Adverse reactions caused by benzodiazepines rarely occur. We present a case of a 70-year-old man who developed a maculopapular exanthema after the ingestion of tetrazepam. For his diagnosis, skin tests were performed, including prick and patch tests, not only with the benzodiazepine implicated in the reaction, but also with benzodiazepines of other groups. Single-blind oral challenge tests were also performed in the patient, in order to assess his tolerance to other benzodiazepines.

  17. Oxygen evolution reaction catalysis

    Science.gov (United States)

    Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

    2016-09-06

    An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

  18. Photoinduced Multicomponent Reactions.

    Science.gov (United States)

    Garbarino, Silvia; Ravelli, Davide; Protti, Stefano; Basso, Andrea

    2016-12-12

    The combination of multicomponent approaches with light-driven processes opens up new scenarios in the area of synthetic organic chemistry, where the need for sustainable, atom- and energy-efficient reactions is increasingly urgent. Photoinduced multicomponent reactions are still in their infancy, but significant developments in this area are expected in the near future. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Problems of rapid growth.

    Science.gov (United States)

    Kim, T D

    1980-01-01

    South Korea's export-oriented development strategy has achieved a remarkable growth record, but it has also brought 2 different problems: 1) since the country's exports accounted for about 1% of total world export volume, the 1st world has become fearful about Korea's aggressive export drive; and 2) the fact that exports account for over 30% of its total gross national product (GNP) exposes the vulnerability of South Korea's economy itself. South Korea continues to be a poor nation, although it is rated as 1 of the most rapidly growing middle income economies. A World Bank 1978 report shows Korea to be 28th of 58 middle income countries in terms of per capita GNP in 1976. Of 11 newly industrializing countries (NIC), 5 in the European continent are more advanced than the others. A recent emphasis on the basic human needs approach has tended to downgrade the concept of GNP. Korea has only an abundant labor force and is without any natural resources. Consequently, Korea utilized an export-oriented development strategy. Oil requirements are met with imports, and almost all raw materials to be processed into exportable products must be imported. To pay import bills Korea must export and earn foreign exchange. It must be emphasized that foreign trade must always be 2-way traffic. In order to export more to middle income countries like Korea, the countries of the 1st world need to ease their protectionist measures against imports from developing countries.

  20. Rapid Polymer Sequencer

    Science.gov (United States)

    Stolc, Viktor (Inventor); Brock, Matthew W (Inventor)

    2013-01-01

    Method and system for rapid and accurate determination of each of a sequence of unknown polymer components, such as nucleic acid components. A self-assembling monolayer of a selected substance is optionally provided on an interior surface of a pipette tip, and the interior surface is immersed in a selected liquid. A selected electrical field is impressed in a longitudinal direction, or in a transverse direction, in the tip region, a polymer sequence is passed through the tip region, and a change in an electrical current signal is measured as each polymer component passes through the tip region. Each of the measured changes in electrical current signals is compared with a database of reference electrical change signals, with each reference signal corresponding to an identified polymer component, to identify the unknown polymer component with a reference polymer component. The nanopore preferably has a pore inner diameter of no more than about 40 nm and is prepared by heating and pulling a very small section of a glass tubing.

  1. Rapidly rotating red giants

    Science.gov (United States)

    Gehan, Charlotte; Mosser, Benoît; Michel, Eric

    2017-10-01

    Stellar oscillations give seismic information on the internal properties of stars. Red giants are targets of interest since they present mixed modes, wich behave as pressure modes in the convective envelope and as gravity modes in the radiative core. Mixed modes thus directly probe red giant cores, and allow in particular the study of their mean core rotation. The high-quality data obtained by CoRoT and Kepler satellites represent an unprecedented perspective to obtain thousands of measurements of red giant core rotation, in order to improve our understanding of stellar physics in deep stellar interiors. We developed an automated method to obtain such core rotation measurements and validated it for stars on the red giant branch. In this work, we particularly focus on the specific application of this method to red giants having a rapid core rotation. They show complex spectra where it is tricky to disentangle rotational splittings from mixed-mode period spacings. We demonstrate that the method based on the identification of mode crossings is precise and efficient. The determination of the mean core rotation directly derives from the precise measurement of the asymptotic period spacing ΔΠ1 and of the frequency at which the crossing of the rotational components is observed.

  2. Management of Infections with Rapidly Growing

    Directory of Open Access Journals (Sweden)

    Jong Hwan Kim

    2012-01-01

    Full Text Available Background Infection caused by rapidly growing mycobacteria (RGM is not uncommon, andthe prevalence of RGM infection has been increasing. Clinical diagnosis is difficult becausethere are no characteristic clinical features. There is also no standard antibiotic regimenfor treating RGM infection. A small series of patients with RGM infections was studied toexamine their treatments and outcomes.Methods A total of 5 patients who had developed postoperative infections from January2009 to December 2010 were retrospectively reviewed. Patients were initially screened using amycobacteria rapid screening test (polymerase chain reaction [PCR]-reverse blot hybridizationassay. To confirm mycobacterial infection, specimens were cultured for nontuberculousmycobacteria and analyzed by 16 S ribosomal RNA and rpoB gene PCR.Results The patients were treated with intravenous antibiotics during hospitalization,and oral antibiotics were administered after discharge. The mean duration of follow-upwas 9 months, and all patients were completely cured of infection with a regimen of acombination of antibiotics plus surgical treatment. Although none of the patients developedrecurrence, there were complications at the site of infection, including hypertrophic scarring,pigmentation, and disfigurement.Conclusions Combination antibiotic therapy plus drainage of surgical abscesses appeared tobe effective for the RGM infections seen in our patients. Although neither the exact dosagenor a standardized regimen has been firmly established, we propose that our treatment canprovide an option for the management of rapidly growing mycobacterial infection.

  3. Maxillary ulceration resulting from using a rapid maxillary expander in a diabetic patient

    OpenAIRE

    Martins Maia, Luiz Guilherme [UNESP; Monini, Andre da Costa [UNESP; Jacob, Helder Baldi; Gandini Júnior, Luiz Gonzaga

    2011-01-01

    One of the characteristics of diabetes mellitus is the exaggerated inflammatory response. The present report shows the reaction from the use of a rapid maxillary expander in a diabetic patient. A 9-year-old child presented an uncommon reaction to the treatment with a rapid maxillary expander, and on follow-up examination, it was discovered that the patient had diabetes mellitus. After controlling the disease, the proposed treatment was used without further incidents. The case calls attention ...

  4. Medications and Drug Allergic Reactions

    Science.gov (United States)

    ... drug allergic reactions TTR Share | Medications and Drug Allergic Reactions This article has been reviewed by Thanai Pongdee, ... your symptoms are severe, seek medical help immediately. Allergic Reactions Allergy symptoms are the result of a chain ...

  5. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  6. Recent advances in N-heterocyclic carbene (NHC-catalysed benzoin reactions

    Directory of Open Access Journals (Sweden)

    Rajeev S. Menon

    2016-03-01

    Full Text Available N-Heterocyclic carbenes (NHCs have emerged as a powerful class of organocatalysts that mediate a variety of organic transformations. The Benzoin reaction constitutes one of the earliest known carbon–carbon bond-forming reactions catalysed by NHCs. The rapid growth of NHC catalysis in general has resulted in the development of a variety of benzoin and benzoin-type reactions. An overview of such NHC-catalysed benzoin reactions is presented.

  7. In Situ FTIR Spectroscopic Monitoring of Electrochemically Controlled Organic Reactions in a Recycle Reactor

    OpenAIRE

    O?Brien, Alexander G; Luca, Oana R.; Baran, Phil S.; Blackmond, Donna G.

    2015-01-01

    An electrochemical cell coupled with a recycle loop through a transmission FTIR cell is employed in studies of two free radical organic reactions, the oxidation of allylic alcohols and the trifluoromethylation of heteroarenes. Rapid mixing through the recycle loop allows continuous monitoring of reaction progress. Electrochemical generation of free radicals allows their controlled mediation into the reaction mixture for more efficient reaction. Kinetic profiles provide mechanistic insight int...

  8. Rapid Active Sampling Package

    Science.gov (United States)

    Peters, Gregory

    2010-01-01

    A field-deployable, battery-powered Rapid Active Sampling Package (RASP), originally designed for sampling strong materials during lunar and planetary missions, shows strong utility for terrestrial geological use. The technology is proving to be simple and effective for sampling and processing materials of strength. Although this originally was intended for planetary and lunar applications, the RASP is very useful as a powered hand tool for geologists and the mining industry to quickly sample and process rocks in the field on Earth. The RASP allows geologists to surgically acquire samples of rock for later laboratory analysis. This tool, roughly the size of a wrench, allows the user to cut away swaths of weathering rinds, revealing pristine rock surfaces for observation and subsequent sampling with the same tool. RASPing deeper (.3.5 cm) exposes single rock strata in-situ. Where a geologist fs hammer can only expose unweathered layers of rock, the RASP can do the same, and then has the added ability to capture and process samples into powder with particle sizes less than 150 microns, making it easier for XRD/XRF (x-ray diffraction/x-ray fluorescence). The tool uses a rotating rasp bit (or two counter-rotating bits) that resides inside or above the catch container. The container has an open slot to allow the bit to extend outside the container and to allow cuttings to enter and be caught. When the slot and rasp bit are in contact with a substrate, the bit is plunged into it in a matter of seconds to reach pristine rock. A user in the field may sample a rock multiple times at multiple depths in minutes, instead of having to cut out huge, heavy rock samples for transport back to a lab for analysis. Because of the speed and accuracy of the RASP, hundreds of samples can be taken in one day. RASP-acquired samples are small and easily carried. A user can characterize more area in less time than by using conventional methods. The field-deployable RASP used a Ni

  9. Rapid Robot Design Validation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies will create a comprehensive software infrastructure for rapid validation of robotic designs. The software will support push-button validation...

  10. Rapid Robot Design Validation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies will create a comprehensive software infrastructure for rapid validation of robot designs. The software will support push-button validation...

  11. Reaction Qualifications Revisited

    DEFF Research Database (Denmark)

    Lippert-Rasmussen, Kasper

    2009-01-01

    of merit. Specifically, it preserves symmetry between negative evaluations of antimeritocratic bases of selection and negative evaluations of qualifications rooted in comparable antimeritocratic reactions. So if employers should not select among applicants on the basis of their (the employers') racial...... preferences, recipients should not respond to the applicant actually hired on the basis of their (the recipients') racial preferences. My account decomposes the meritocratic ideal into four separate norms, one of which applies to recipients rather than to selectors. Finally, it defends the view that reaction...... reaction-qualifications are entirely irrelevant from the point of view of merit, the view expounded here implies that the ideal of meritocracy and the norm of non-discrimination are less closely tied than theorists like Andrew Mason and David Miller believe.  ...

  12. Allergic reactions in anaesthesia

    DEFF Research Database (Denmark)

    Krøigaard, M; Garvey, L H; Menné, T

    2005-01-01

    BACKGROUND: The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC). METHODS: Case...... notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction. RESULTS: In 67 cases, one or more substances were suspected. In 49...... of these (73%) the suspected cause did not match the results of subsequent investigation, either a different substance being the cause or no cause being found. Only five cases (7%) showed a complete match between suspected cause and investigation result. In the remaining 13 cases (19%) there was a partial...

  13. Hipersensitivity Reactions to Corticosteroids.

    Science.gov (United States)

    Berbegal, L; DeLeon, F J; Silvestre, J F

    2016-03-01

    Corticosteroids are widely used drugs in the clinical practice, especially by topic application in dermatology. These substances may act as allergens and produce immediate and delayed hypersensitivity reactions. Allergic contact dermatitis is the most frequent presentation of corticosteroid allergy and it should be studied by patch testing in specific units. The corticosteroids included in the Spanish standard battery are good markers but not ideal. Therefore, if those makers are positive, it is useful to apply a specific battery of corticosteroids and the drugs provided by patients. Immediate reactions are relatively rare but potentially severe, and it is important to confirm the sensitization profile and to guide the use of alternative corticosteroids, because they are often necessary in several diseases. In this article we review the main concepts regarding these two types of hypersensitivity reactions in corticosteroid allergy, as well as their approach in the clinical practice. Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved.

  14. Nanoparticle Reactions on Chip

    Science.gov (United States)

    Köhler, J. M.; Kirner, Th.; Wagner, J.; Csáki, A.; Möller, R.; Fritzsche, W.

    The handling of heterogenous systems in micro reactors is difficult due to their adhesion and transport behaviour. Therefore, the formation of precipitates and gas bubbles has to be avoided in micro reaction technology, in most cases. But, micro channels and other micro reactors offer interesting possibilities for the control of reaction conditions and transport by diffusion and convection due to the laminar flow caused by small Reynolds numbers. This can be used for the preparation and modification of objects, which are much smaller than the cross section of microchannels. The formation of colloidal solutions and the change of surface states of nano particles are two important tasks for the application of chip reactors in nanoparticle technology. Some concepts for the preparation and reaction of nanoparticles in modular chip reactor arrangements will be discussed.

  15. Adverse reactions to cosmetics

    Directory of Open Access Journals (Sweden)

    Dogra A

    2003-03-01

    Full Text Available Adverse reaction to cosmetics constitute a small but significant number of cases of contact dermatitis with varied appearances. These can present as contact allergic dermatitis, photodermatitis, contact irritant dermatitis, contact urticaria, hypopigmentation, hyperpigmentotion or depigmentation, hair and nail breakage. Fifty patients were included for the study to assess the role of commonly used cosmetics in causing adverse reactions. It was found that hair dyes, lipsticks and surprisingly shaving creams caused more reaction as compared to other cosmetics. Overall incidence of contact allergic dermatitis seen was 3.3% with patients own cosmetics. Patch testing was also done with the basic ingredients and showed positive results in few cases where casual link could be established. It is recommended that labeling of the cosmetics should be done to help the dermatologists and the patients to identify the causative allergen in cosmetic preparation.

  16. Velocity pump reaction turbine

    Science.gov (United States)

    House, P.A.

    An expanding hydraulic/two-phase velocity pump reaction turbine including a dual concentric rotor configuration with an inter-rotor annular flow channel in which the inner rotor is mechanically driven by the outer rotor. In another embodiment, the inner rotor is immobilized and provided with gas recovery ports on its outer surface by means of which gas in solution may be recovered. This velocity pump reaction turbine configuration is capable of potential energy conversion efficiencies of up to 70%, and is particularly suited for geothermal applications.

  17. Knockout reactions: experimental aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D. [Santiago de Compostela Univ. (Spain)

    2007-07-01

    The availability of radioactive beams has given rise to intense activity in the field of direct reactions. The removal of one(two)-nucleon (referred to as nucleon knockout in this text) from a fast exotic projectile has been extensively investigated. This lecture provides a general overview of the experimental results achieved using this technique. The sensitivity of the method to different experimental aspects is illustrated with a few examples. Special attention is given to the application of nucleon-knockout reactions as a general purpose spectroscopic tool. (author)

  18. Rationalizing thermal reactions of C6Lix negative electrode with nonaqueous electrolyte

    Science.gov (United States)

    Mukai, Kazuhiko; Inoue, Takao; Hasegawa, Madoka

    2017-10-01

    Exothermic reactions at elevated temperatures (T) between Li-intercalated C6Lix negative electrodes and nonaqueous electrolytes play a crucial role in the thermal runaway of lithium-ion batteries. However, despite intensive studies so far, the origin of the reactions has not been fully understood, particularly from the viewpoint of a material balance. In this paper, we performed differential scanning calorimetry (DSC) analyses up to 450 °C for samples with x = 0.22, 0.45, 0.67, and 0.89, which were prepared from a graphited mesophase-pitch-based carbon fiber. The DSC profiles for C6Lix with 1 M LiPF6 dissolved in ethylene carbonate (EC)/diethylene carbonate (DEC) solution (EC/DEC = 3/7 by volume) were found to be divided into four different T regions regardless of x. That is, Region (I) below 150 °C, Region (II) for 150 °C < T ≤ 240 °C, Region (III) for 240 °C < T ≤ 270 °C, and Region (IV) above 270 °C. By combining with results for X-ray diffraction measurements and scanning electron microscopic analyses, we have rationalized the change in enthalpy (ΔH) of each Region taking into account the given material balance. Strategies for inhibiting the thermal runaway of LIBs are also discussed.

  19. A spectrophotometric study of the reaction of copigmentation of malvin and tannic acid

    Directory of Open Access Journals (Sweden)

    JASMINA M. DIMITRIC-MARKOVIC

    1999-10-01

    Full Text Available The reaction of copigmentation of malvidin 3,5-diglucoside and tannic acid of the ester type was studied. The interactions of these molecules were observed via UV-VIS absorption spectroscopy. It was established that the pH of the medium, the concentration of the copigmentating molecules, and the temperature affect the copigmentation process. The calculated equilibrium constant of the reaction of pH 3.00 is K = 226.9, and at pH 3.65 it is K = 277.0. The change of the Gibbs free energy in pH 3.00 buffer is DG = -13.4 kJ/mol, and in pH 3.65 buffer it is DG = -13.9 kJ/mol. The stoichiometric ratio of the components in the copigment is 1:1, at both pH values. It is evident from the calculated values of the thermodynamic functions that the process is thermodynamically favorable in the lower temperature range. Temperature appears as the basic parameter of the thermodynamic feasability of the process, since the copigmentation process is exothermic (DHpH=3.00 = - 41.6 kJ/mol and DHpH=3.65 = - 41.6 kJ/mol and proceeds with a decrease in entropy (DSpH=3.00 = - 94.4 J/mol K and DSpH=3.65 = -92.7 J/mol K.

  20. Toluene destruction in the Claus process by sulfur dioxide: A reaction kinetics study

    KAUST Repository

    Sinha, Sourab

    2014-10-22

    The presence of aromatics such as benzene, toluene, and xylene (BTX) as contaminants in the H2S gas stream entering Claus sulfur recovery units has a detrimental effect on catalytic reactors, where BTX forms soot particles and clogs and deactivates the catalysts. BTX oxidation, before they enter catalyst beds, can solve this problem. A theoretical investigation is presented on toluene oxidation by SO2. Density functional theory is used to study toluene radical (benzyl, o-methylphenyl, m-methylphenyl, and p-methylphenyl)-SO2 interactions. The mechanism begins with SO2 addition on the radical through one of the O atoms rather than the S atom. This exothermic reaction involves energy barriers of 4.8-6.1 kJ/mol for different toluene radicals. Thereafter, O-S bond scission takes place to release SO. The reaction rate constants are evaluated to facilitate process simulations. Among four toluene radicals, the resonantly stabilized benzyl radical exhibited lowest SO2 addition rate. A remarkable similarity between toluene oxidation by O2 and by SO2 is observed.

  1. Rapid prototyping in medical sciences

    Directory of Open Access Journals (Sweden)

    Ákos Márk Horváth

    2015-09-01

    Full Text Available Even if it sound a bit incredible rapid prototyping (RPT as production method has been used for decades in other professions. Nevertheless medical science just started discover the possibilities of this technology and use the offered benefits of 3D printing. In this paper authors have investigated the pharmaceutical usage of rapid prototyping.

  2. cyclopropanation reaction with ketene

    Indian Academy of Sciences (India)

    Administrator

    Smith. 15. This has motivated a large number of research groups to develop new and wide-range methods to produce cyclopropanated products. Methylene insertion by a carbenoid species into the. C=C bond is one of the most widely used methods since the recognition of the Simmons–Smith reac- tion, which is a reaction ...

  3. Reaction product imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, D.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    Over the past few years the author has investigated the photochemistry of small molecules using the photofragment imaging technique. Bond energies, spectroscopy of radicals, dissociation dynamics and branching ratios are examples of information obtained by this technique. Along with extending the technique to the study of bimolecular reactions, efforts to make the technique as quantitative as possible have been the focus of the research effort. To this end, the author has measured the bond energy of the C-H bond in acetylene, branching ratios in the dissociation of HI, the energetics of CH{sub 3}Br, CD{sub 3}Br, C{sub 2}H{sub 5}Br and C{sub 2}H{sub 5}OBr dissociation, and the alignment of the CD{sub 3} fragment from CD{sub 3}I photolysis. In an effort to extend the technique to bimolecular reactions the author has studied the reaction of H with HI and the isotopic exchange reaction between H and D{sub 2}.

  4. Reaction Formulation: A Bibliography.

    Science.gov (United States)

    Pedrini, D. T.; Pedrini, Bonnie C.

    Reaction formation was studied by Sigmund Freud. This defense mechanism may be related to repression, substitution, reversal, and compensation (or over-compensation). Alfred Adler considered compensation a basic process in his individual psychology. Anna Freud discussed some defense mechanisms, and Bibring, Dwyer, Huntington, and Valenstein…

  5. Explaining competitive reaction effects

    NARCIS (Netherlands)

    Leeflang, P.S.H.; Wittink, D.R.

    Changes in promotional expenditure decisions for a brand, as in other marketing decisions, should be based on the expected impact on purchase and consumption behavior as well as on the likely reactions by competitors. Purchase behavior may be predicted from estimated demand functions. Competitive

  6. Cluster knockout reactions

    Indian Academy of Sciences (India)

    2014-04-07

    Apr 7, 2014 ... Cluster knockout reactions are expected to reveal the amount of clustering (such as that of , d and even of heavier clusters such as 12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it ...

  7. Transfer reactions with HELIOS

    Science.gov (United States)

    Wuosmaa, Alan H.

    2011-04-01

    Nucleon-transfer reactions have formed the backbone of nuclear-structure studies for several decades, providing a wealth of information about the energies, quantum numbers, and wave functions of single-particle states in nuclei throughout the nuclear chart. Current trends in nuclear-structure physics and the modern emphasis on properties of neutron-rich nuclei far from stability have renewed interest in such transfer reactions with radioactive beams. Here, the usual combination of light beam and heavy target cannot be used, and measurements must be performed in ``inverse kinematics,'' with a heavy, unstable beam incident on a light target. This arrangement introduces several technical difficulties, including the identification of the reaction products and the resolution of the states of interest in the residual nuclei. A new device, HELIOS (the HELIcal Orbit Spectrometer) at the ATLAS facility at Argonne National Laboratory, solves many of the problems encountered with inverse kinematics including particle identification and energy resolution in the center-of-mass frame. The device utilizes the uniform magnetic field of a large, superconducting solenoid to transport light reaction products from the target to a linear array of position-sensitive silicon detectors. The properties of HELIOS will be described, and examples from the initial research program that focuses on neutron transfer with the (d,p) reaction, using both stable and unstable beams with mass A = 11 to 136, will be presented. Work supported by the U. S. Department of Energy, Office of Nuclear Physics under contract numbers DE-FG02-04ER41320 (WMU) and DE-AC02-06CH11357 (ANL).

  8. A combined high-temperature experimental and theoretical kinetic study of the reaction of dimethyl carbonate with OH radicals.

    Science.gov (United States)

    Khaled, Fethi; Giri, Binod Raj; Szőri, Milán; Mai, Tam V-T; Huynh, Lam K; Farooq, Aamir

    2017-03-08

    The reaction kinetics of dimethyl carbonate (DMC) and OH radicals were investigated behind reflected shock waves over the temperature range of 872-1295 K and at pressures near 1.5 atm. Reaction progress was monitored by detecting OH radicals at 306.69 nm using a UV laser absorption technique. The rate coefficients for the reaction of DMC with OH radicals were extracted using a detailed kinetic model developed by Glaude et al. (Proc. Combust. Inst. 2005, 30(1), 1111-1118). The experimental rate coefficients can be expressed in Arrhenius form as: kexpt'l = 5.15 × 10(13) exp(-2710.2/T) cm(3) mol(-1) s(-1). To explore the detailed chemistry of the DMC + OH reaction system, theoretical kinetic analyses were performed using high-level ab initio and master equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) calculations. Geometry optimization and frequency calculations were carried out at the second-order Møller-Plesset (MP2) perturbation level of theory using Dunning's augmented correlation consistent-polarized valence double-ζ basis set (aug-cc-pVDZ). The energy was extrapolated to the complete basis set using single point calculations performed at the CCSD(T)/cc-pVXZ (where X = D, T) level of theory. For comparison purposes, additional ab initio calculations were also carried out using composite methods such as CBS-QB3, CBS-APNO, G3 and G4. Our calculations revealed that the H-abstraction reaction of DMC by OH radicals proceeds via an addition elimination mechanism in an overall exothermic process, eventually forming dimethyl carbonate radicals and H2O. Theoretical rate coefficients were found to be in excellent agreement with those determined experimentally. Rate coefficients for the DMC + OH reaction were combined with literature rate coefficients of four straight chain methyl ester + OH reactions to extract site-specific rates of H-abstraction from methyl esters by OH radicals.

  9. Multicomponent reactions in polymer synthesis.

    Science.gov (United States)

    Kakuchi, Ryohei

    2014-01-03

    More participants, yet efficient reactions: Multicomponent reactions (MCRs) have found application in polymer chemistry both in the synthesis of multifunctional monomers and in post-polymerization modification. Examples include the Passerini three-component reaction, the Ugi four-component reaction, and the copper-catalyzed MCR. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Kinetics of Bio-Reactions

    DEFF Research Database (Denmark)

    Villadsen, John

    2015-01-01

    his chapter predicts the specific rates of reaction by means of a mathematical expression, the kinetics of the reaction. This expression can be derived through a mechanistic interpretation of an enzymatically catalyzed reaction, but it is essentially of empirical nature for cell reactions. The mo...

  11. What Is a Reaction Rate?

    Science.gov (United States)

    Schmitz, Guy

    2005-01-01

    The definition of reaction rate is derived and demonstrations are made for the care to be taken while using the term. Reaction rate can be in terms of a reaction property, the extent of reaction and thus it is possible to give a definition applicable in open and closed systems.

  12. Elucidating reaction mechanisms on quantum computers

    Science.gov (United States)

    Reiher, Markus; Wiebe, Nathan; Svore, Krysta M.; Wecker, Dave; Troyer, Matthias

    2017-01-01

    With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources. PMID:28674011

  13. Elucidating reaction mechanisms on quantum computers.

    Science.gov (United States)

    Reiher, Markus; Wiebe, Nathan; Svore, Krysta M; Wecker, Dave; Troyer, Matthias

    2017-07-18

    With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources.

  14. Elucidating reaction mechanisms on quantum computers

    Science.gov (United States)

    Reiher, Markus; Wiebe, Nathan; Svore, Krysta M.; Wecker, Dave; Troyer, Matthias

    2017-07-01

    With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources.

  15. Solvent effect on the degree of (a)synchronicity in polar Diels-Alder reactions from the perspective of the reaction force constant analysis.

    Science.gov (United States)

    Yepes, Diana; Martínez-Araya, Jorge I; Jaque, Pablo

    2017-12-29

    In this work, we computationally evaluated the influence of six different molecular solvents, described as a polarizable continuum model at the M06-2X/6-31+G(d,p) level, on the activation barrier/reaction rate, overall energy change, TS geometry, and degree of (a)synchronicity of two concerted Diels-Alder cycloadditions of acrolein (R1) and its complex with Lewis acid acrolein···BH3 (R2) to cyclopentadiene. In gas-phase, we found that both exothermicity and activation barrier are only reduced by about 2.0 kcal mol-1, and the asynchronicity character of the mechanism is accentuated when BH3 is included. An increment in the solvent's polarity lowers the activation energy of R1 by 1.3 kcal mol-1, while for R2 the reaction rate is enhanced by more than 2000 times at room temperature (i.e., the activation energy decreases by 4.5 kcal mol-1) if the highest polar media is employed. Therefore, a synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together. This effect was ascribed to the ability of the solvent to favor the encounter between cyclopentadiene and acrolein···BH3. This was validated by the asymmetry of the TS which becomes highly pronounced when either both or just BH3 is considered or the solvent's polarity is increased. Finally, the reaction force constant κ(ξ) reveals that an increment in the solvent's polarity is able to turn a moderate asynchronous mechanism of the formation of the new C-C σ-bonds into a highly asynchronous one. Graphical abstract A synergistic effect is achieved when both external agents, i.e., Lewis acid catalyst and polar solvent, are included together: lowered energy barriers and increased asynchronicities.

  16. Propionate Exchange Reactions in Methanogenic Ecosystems †

    Science.gov (United States)

    Boone, David R.

    1984-01-01

    Propionate degradation was measured with [1-14C]- and [2-14C]propionate in an anaerobic digestor. When [1-14C]propionate was used, label disappeared more rapidly from the propionate pool than when [2-14C]propionate was used. This indicated that an exchange reaction involving the carboxyl group of propionate occurred. Labeled propionate added to digestor samples which were equilibrated with H2 lost label from the carboxyl group but not from the methylene group. PMID:16346651

  17. Transformational leadership: a cascading chain reaction.

    Science.gov (United States)

    Murphy, Lorraine

    2005-03-01

    Historical influences still permeate contemporary nursing practise. These are mirrored in organizational philosophies, transactional and autocratic leadership styles and disempowered staff. Whilst there is disparity amongst the theorists' definitions of leadership, there is consensus pertaining to the attributes necessary to realize effective leadership. Transformational leadership is heralded as new criterion for nurse managers, and can be achieved through training, education and professional development in key leadership competencies. To achieve a chain reaction, charismatic transformational leaders espouse intellectual stimulation and individual consideration to empower staff and enhance patient care. Nurse managers that develop and foster transformational leadership can surmount oppressive traditions and confidently navigate a complex and rapidly changing health care environment.

  18. Welding of aluminum alloys through thermite like reactions in Al-CuO-Ni system

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami Motlagh, Ehsan, E-mail: ehsan.bahramimotlagh@stu-mail.um.ac.ir [Department of Materials Science and Engineering, Engineering Faculty, Ferdowsi University of Mashhad, P.O. Box 9177948944, Mashhad (Iran, Islamic Republic of); Vahdati Khaki, Jalil; Haddad Sabzevar, Mohsen [Department of Materials Science and Engineering, Engineering Faculty, Ferdowsi University of Mashhad, P.O. Box 9177948944, Mashhad (Iran, Islamic Republic of)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Combustion synthesis reactions were utilized for welding of aluminum alloys. Black-Right-Pointing-Pointer A composite joint reinforced by different intermetallic compounds was obtained. Black-Right-Pointing-Pointer Using metal oxides as a part of raw materials makes the welding process economical. Black-Right-Pointing-Pointer Furthermore, this process introduces new applications for thermite reactions. - Abstract: In this work, first, a metastable composite powder of '14Al-3CuO-Ni' with a decreased ignition temperature was obtained via Arrested Reactive Milling (ARM), then this exothermic blend was used for welding of 1100 Aluminum alloy. The reactive media and the weld zones were investigated using scanning electron microscope. X-ray diffraction experiment and morphological investigations accompanied with the EDS analyses were carried out in order to evaluate the reactions' products. Vickers microhardness profile across the joint and the shear strength of the joints were determined. The weld zone thickness in each of the parent alloys was measured to be 750 {mu}m, approximately. Results showed that different reactions occurring during the process lead to the in situ formation of different intermetallic compounds such as Al{sub 3}Ni{sub 2} and Al{sub 7}Cu{sub 4}Ni as well as Al{sub 2}O{sub 3} nanoparticles at the interface. Thus, this area has the maximum hardness (80-90 VHN) and the minimum hardness of 35 VHN belongs to the parent alloys. The mean shear strength of the obtained joints was 27 MPa.

  19. Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide

    KAUST Repository

    Sinha, Sourab

    2015-09-24

    In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation. © 2015 American Chemical Society.

  20. How Rapid is Rapid Prototyping? Analysis of ESPADON Programme Results

    Directory of Open Access Journals (Sweden)

    Ian D. Alston

    2003-05-01

    Full Text Available New methodologies, engineering processes, and support environments are beginning to emerge for embedded signal processing systems. The main objectives are to enable defence industry to field state-of-the-art products in less time and with lower costs, including retrofits and upgrades, based predominately on commercial off the shelf (COTS components and the model-year concept. One of the cornerstones of the new methodologies is the concept of rapid prototyping. This is the ability to rapidly and seamlessly move from functional design to the architectural design to the implementation, through automatic code generation tools, onto real-time COTS test beds. In this paper, we try to quantify the term “rapid” and provide results, the metrics, from two independent benchmarks, a radar and sonar beamforming application subset. The metrics show that the rapid prototyping process may be sixteen times faster than a conventional process.

  1. Composition and method for storing and releasing hydrogen

    Science.gov (United States)

    Thorn, David L.; Tumas, William; Ott, Kevin C.; Burrell, Anthony K.

    2010-06-15

    A chemical system for storing and releasing hydrogen utilizes an endothermic reaction that releases hydrogen coupled to an exothermic reaction to drive the process thermodynamically, or an exothermic reaction that releases hydrogen coupled to an endothermic reaction.

  2. Context-Driven Exploration of Complex Chemical Reaction Networks.

    Science.gov (United States)

    Simm, Gregor N; Reiher, Markus

    2017-12-12

    The construction of a reaction network containing all relevant intermediates and elementary reactions is necessary for the accurate description of chemical processes. In the case of a complex chemical reaction (involving, for instance, many reactants or highly reactive species), the size of such a network may grow rapidly. Here, we present a computational protocol that constructs such reaction networks in a fully automated fashion steered in an intuitive, graph-based fashion through a single graphical user interface. Starting from a set of initial reagents new intermediates are explored through intra- and intermolecular reactions of already explored intermediates or new reactants presented to the network. This is done by assembling reactive complexes based on heuristic rules derived from conceptual electronic-structure theory and exploring the corresponding approximate reaction path. A subsequent path refinement leads to a minimum-energy path which connects the new intermediate to the existing ones to form a connected reaction network. Tree traversal algorithms are then employed to detect reaction channels and catalytic cycles. We apply our protocol to the formose reaction to study different pathways of sugar formation and to rationalize its autocatalytic nature.

  3. Polymerase chain reaction: Theory, practice and application: A review

    African Journals Online (AJOL)

    Polymerase Chain Reaction (PCR) is a rapid procedure for in vitro enzymatic amplification of specific DNA sequences using two oligonucleotide primers that hybridize to opposite strands and flank the region of interest in the target DNA. Repetitive cycles involving template denaturation, primer annealing and the extension ...

  4. An overview on the application of Polymerase Chain Reaction (PCR ...

    African Journals Online (AJOL)

    This overview describes the principle of polymerase chain reaction as one of the most important techniques used in the diagnosis of bacterial infections due to its reliability, sensitivity and rapidness. It also identifies some of the limitations of the technique as well as some of the bacterial infections that can be diagnosed ...

  5. Development of a sensitive nested-polymerase chain reaction (PCR ...

    African Journals Online (AJOL)

    A species-specific polymerase chain reaction (PCR) assay was developed for rapid and accurate detection of Ustilago scitaminea, the causal agent of sugarcane smut disease. Based on nucleotide differences in the internal transcribed spacer (ITS) sequences of U. scitaminea, a pair of species-specific primers, SL1 ...

  6. Reaction Diffusion and Chemotaxis for Decentralized Gathering on FPGAs

    Directory of Open Access Journals (Sweden)

    Bernard Girau

    2009-01-01

    and rapid simulations of the complex dynamics of this reaction-diffusion model. Then we describe the FPGA implementation of the environment together with the agents, to study the major challenges that must be solved when designing a fast embedded implementation of the decentralized gathering model. We analyze the results according to the different goals of these hardware implementations.

  7. an overview on the application of polymerase chain reaction (pcr)

    African Journals Online (AJOL)

    DR. AMINU

    ABSTRACT. This overview describes the principle of polymerase chain reaction as one of the most important techniques used in the diagnosis of bacterial infections due to its reliability, sensitivity and rapidness. It also identifies some of the limitations of the technique as well as some of the bacterial infections that can be ...

  8. TaqMan Real-Time Polymerase Chain Reaction and ...

    African Journals Online (AJOL)

    TaqMan Real-Time Polymerase Chain Reaction and. Pyrosequencing using Single Nucleotide Polymorphism. Protocol for Rapid Determination of ALDH2 *2 in a Chinese. Population. Ju-yi Li1, Jin-hu Wu2, Yan Zhang2, Xiu-fang Wang2, Jie Jin2 and Yi Wang1*. 1Department of Pharmacy, The Central Hospital of Wuhan, ...

  9. Reaction chemistry of cerium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    It is truly ironic that a synthetic organic chemist likely has far greater knowledge of the reaction chemistry of cerium(IV) than an inorganic colleague. Cerium(IV) reagents have long since been employed as oxidants in effecting a wide variety of organic transformations. Conversely, prior to the late 1980s, the number of well characterized cerium(IV) complexes did not extend past a handful of known species. Though in many other areas, interest in the molecular chemistry of the 4f-elements has undergone an explosive growth over the last twenty years, the chemistry of cerium(IV) has for the most part been overlooked. This report describes reactions of cerium complexes and structure.

  10. Reactions to dietary tartrazine.

    Science.gov (United States)

    David, T J

    1987-01-01

    Double blind challenges with tartrazine and benzoic acid were performed in hospital in 24 children whose parents gave a definite history of a purely behavioural immediate adverse reaction to one of these substances. The patients, whose ages ranged from 1.6 to 12.4 years, were on a diet that avoided these items, and in all there was a clear history that any lapse of the diet caused an obvious adverse behavioural reaction within two hours. In no patient was any change in behaviour noted either by the parents or the nursing staff after the administration of placebo or active substances. Twenty two patients returned to a normal diet without problems, but the parents of two children insisted on continuing the diet. While popular belief has it that additives may have harmful behavioural effects, objective verification is required to prevent overdiagnosis. PMID:3548601

  11. Enzyme catalysed tandem reactions.

    Science.gov (United States)

    Oroz-Guinea, Isabel; García-Junceda, Eduardo

    2013-04-01

    To transfer to the laboratory, the excellent efficiency shown by enzymes in Nature, biocatalysis, had to mimic several synthetic strategies used by the living organisms. Biosynthetic pathways are examples of tandem catalysis and may be assimilated in the biocatalysis field for the use of isolated multi-enzyme systems in the homogeneous phase. The concurrent action of several enzymes that work sequentially presents extraordinary advantages from the synthetic point of view, since it permits a reversible process to become irreversible, to shift the equilibrium reaction in such a way that enantiopure compounds can be obtained from prochiral or racemic substrates, reduce or eliminate problems due to product inhibition or prevent the shortage of substrates by dilution or degradation in the bulk media, etc. In this review we want to illustrate the developments of recent studies involving in vitro multi-enzyme reactions for the synthesis of different classes of organic compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Rapid flow-based peptide synthesis.

    Science.gov (United States)

    Simon, Mark D; Heider, Patrick L; Adamo, Andrea; Vinogradov, Alexander A; Mong, Surin K; Li, Xiyuan; Berger, Tatiana; Policarpo, Rocco L; Zhang, Chi; Zou, Yekui; Liao, Xiaoli; Spokoyny, Alexander M; Jensen, Klavs F; Pentelute, Bradley L

    2014-03-21

    A flow-based solid-phase peptide synthesis methodology that enables the incorporation of an amino acid residue every 1.8 min under automatic control or every 3 min under manual control is described. This is accomplished by passing a stream of reagent through a heat exchanger into a low volume, low backpressure reaction vessel, and through a UV detector. These features enable continuous delivery of heated solvents and reagents to the solid support at high flow rate, thereby maintaining maximal concentration of reagents in the reaction vessel, quickly exchanging reagents, and eliminating the need to rapidly heat reagents after they have been added to the vessel. The UV detector enables continuous monitoring of the process. To demonstrate the broad applicability and reliability of this method, it was employed in the total synthesis of a small protein, as well as dozens of peptides. The quality of the material obtained with this method is comparable to that for traditional batch methods, and, in all cases, the desired material was readily purifiable by RP-HPLC. The application of this method to the synthesis of the 113-residue Bacillus amyloliquefaciens RNase and the 130-residue DARPin pE59 is described in the accompanying manuscript. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A rapid molecular approach for chromosomal phasing.

    Directory of Open Access Journals (Sweden)

    John F Regan

    Full Text Available Determining the chromosomal phase of pairs of sequence variants - the arrangement of specific alleles as haplotypes - is a routine challenge in molecular genetics. Here we describe Drop-Phase, a molecular method for quickly ascertaining the phase of pairs of DNA sequence variants (separated by 1-200 kb without cloning or manual single-molecule dilution. In each Drop-Phase reaction, genomic DNA segments are isolated in tens of thousands of nanoliter-sized droplets together with allele-specific fluorescence probes, in a single reaction well. Physically linked alleles partition into the same droplets, revealing their chromosomal phase in the co-distribution of fluorophores across droplets. We demonstrated the accuracy of this method by phasing members of trios (revealing 100% concordance with inheritance information, and demonstrate a common clinical application by phasing CFTR alleles at genomic distances of 11-116 kb in the genomes of cystic fibrosis patients. Drop-Phase is rapid (requiring less than 4 hours, scalable (to hundreds of samples, and effective at long genomic distances (200 kb.

  14. CMLSnap : Animated reaction mechanisms

    OpenAIRE

    Holliday, Gemma L; Mitchell, John BO; Murray-Rust, Peter

    2004-01-01

    The authors thank the EPSRC for financial support of this project and Unilever for their support of the Centre for Molecular Science Informatics. Reactions with many steps can be represented by a single XML-based table of the atoms, bonds and electrons. For each step the complete Chemical Markup Language 1 representation of all components is obtained and a snapshot representing the end point of the step is generated. These snapshots can then be combined to give an animated description of t...

  15. Exclusive reactions in QCD

    OpenAIRE

    Pire, Bernard

    1996-01-01

    We review the theory of hard exclusive scattering in Quantum Chromodynamics. After recalling the classical counting rules which describe the leading scale dependence of form factors and exclusive cross-sections at fixed angle, the pedagogical example of the pion form factor is developped in some detail in order to show explicitely what factorization means in the QCD framework. The picture generalizes to many hard reactions which are at the heart of the ELFE project. We briefly present the con...

  16. Photochemical reaction dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.C. [Lawrence Berkeley Laboratory, Livermore, CA (United States)

    1993-12-01

    The purpose of the program is to develop a fundamental understanding of unimolecular and bimolecular reaction dynamics with application in combustion and energy systems. The energy dependence in ketene isomerization, ketene dissociation dynamics, and carbonyl substitution on organometallic rhodium complexes in liquid xenon have been studied. Future studies concerning unimolecular processes in ketene as well as energy transfer and kinetic studies of methylene radicals are discussed.

  17. A Rapid Compression Expansion Machine (RCEM) for studying chemical kinetics: Experimental principle and first applications

    CERN Document Server

    Werler, Marc; Maas, Ulrich

    2016-01-01

    A novel extension of a rapid compression machine (RCM), namely a Rapid Compression Expansion Machine (RCEM), is described and its use for studying chemical kinetics is demonstrated. Like conventional RCMs, the RCEM quickly compresses a fuel/air mixture by pushing a piston into a cylinder; the resulting high temperatures and pressures initiate chemical reactions. In addition, the machine can rapidly expand the compressed gas in a controlled way by pulling the piston outwards again. This freezes chemical activity after a pre-defined reaction duration, and therefore allows a convenient probe sampling and ex-situ gas analysis of stable species. The RCEM therefore is a promising instrument for studying chemical kinetics, including also partially reacted fuel/air mixtures. The setup of the RCEM, its experimental characteristics and its use for studying chemical reactions are outlined in detail. To allow comparisons of RCEM results with predictions of chemical reaction mechanisms, a simple numerical model of the RCE...

  18. Cryochemical chain reactions

    Science.gov (United States)

    Barkalov, I. M.; Kiryukhin, D. P.

    The possibility of a chemical reaction near absolute zero has appeared doubtful since the beginning of the 1970s. The existing ideas must be revised after the radiation polymerization of formaldehyde at 4.2 K has been observed. In glassy systems, we have examined chain processes that occur under sharp (by five to six orders) changes in molecular mobility of the medium in the region of matrix devitrification. Quite unusual mechano-energetic chains of chemical conversion arise in the studied systems submerged in liquid helium. The chemical transformation initiated by local brittle fracture travels over the sample as an autowave. A series of experimental and theoretical investigations devoted to this interesting phenomenon are described. There is no generalization in this new region of chemistry up to this time. Many journal articles and reviews have been previously published only in Russian. The cycles of investigations of chain cryochemical reactions are the subject of this review. We hope that the investigation of the extraordinary peculiarities of chain cryochemical reactions should produce new ideas in chemical theory and industry.

  19. Adverse cutaneous drug reaction

    Directory of Open Access Journals (Sweden)

    Nayak Surajit

    2008-01-01

    Full Text Available In everyday clinical practice, almost all physicians come across many instances of suspected adverse cutaneous drug reactions (ACDR in different forms. Although such cutaneous reactions are common, comprehensive information regarding their incidence, severity and ultimate health effects are often not available as many cases go unreported. It is also a fact that in the present world, almost everyday a new drug enters market; therefore, a chance of a new drug reaction manifesting somewhere in some form in any corner of world is unknown or unreported. Although many a times, presentation is too trivial and benign, the early identification of the condition and identifying the culprit drug and omit it at earliest holds the keystone in management and prevention of a more severe drug rash. Therefore, not only the dermatologists, but all practicing physicians should be familiar with these conditions to diagnose them early and to be prepared to handle them adequately. However, we all know it is most challenging and practically difficult when patient is on multiple medicines because of myriad clinical symptoms, poorly understood multiple mechanisms of drug-host interaction, relative paucity of laboratory testing that is available for any definitive and confirmatory drug-specific testing. Therefore, in practice, the diagnosis of ACDR is purely based on clinical judgment. In this discussion, we will be primarily focusing on pathomechanism and approach to reach a diagnosis, which is the vital pillar to manage any case of ACDR.

  20. Modelling Tethered Enzymatic Reactions

    Science.gov (United States)

    Solis Salas, Citlali; Goyette, Jesse; Coker-Gordon, Nicola; Bridge, Marcus; Isaacson, Samuel; Allard, Jun; Maini, Philip; Dushek, Omer

    Enzymatic reactions are key to cell functioning, and whilst much work has been done in protein interaction in cases where diffusion is possible, interactions of tethered proteins are poorly understood. Yet, because of the large role cell membranes play in enzymatic reactions, several reactions may take place where one of the proteins is bound to a fixed point in space. We develop a model to characterize tethered signalling between the phosphatase SHP-1 interacting with a tethered, phosphorylated protein. We compare our model to experimental data obtained using surface plasmon resonance (SPR). We show that a single SPR experiment recovers 5 independent biophysical/biochemical constants. We also compare the results between a three dimensional model and a two dimensional model. The work gives the opportunity to use known techniques to learn more about signalling processes, and new insights into how enzyme tethering alters cellular signalling. With support from the Mexican Council for Science and Technology (CONACyT), the Public Education Secretariat (SEP), and the Mexican National Autonomous University's Foundation (Fundacion UNAM).